POSITIVE ACTIVE MATERIAL FOR SECONDARY BATTERY AND METHOD THEREOF
20250361154 · 2025-11-27
Inventors
Cpc classification
C01P2004/61
CHEMISTRY; METALLURGY
H01M4/525
ELECTRICITY
C01G53/50
CHEMISTRY; METALLURGY
C01P2002/74
CHEMISTRY; METALLURGY
C01P2004/62
CHEMISTRY; METALLURGY
C01G53/506
CHEMISTRY; METALLURGY
H01M4/505
ELECTRICITY
Y02E60/10
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
C01P2004/54
CHEMISTRY; METALLURGY
C01P2002/72
CHEMISTRY; METALLURGY
C01G53/504
CHEMISTRY; METALLURGY
International classification
Abstract
The present invention includes a positive electrode active material for a secondary battery, comprising a composite metal hydroxide precursor represented by Chemical Formula (1) below: wherein the precursor includes a secondary particle composed of a plurality of primary particles; wherein each primary particle is formed as a bundle of micro primary particles; wherein, when observed via a transmission electron microscope, the major axis direction of the micro primary particles coincides with the major axis direction of the primary particles; and wherein each micro primary particle has a thickness of about 1 nm to about 50 nm.
##STR00001##
Claims
1. A positive electrode active material for a secondary battery, the positive electrode active material comprising: a composite metal hydroxide precursor represented by Chemical Formula 1 below: wherein the precursor includes a secondary particle composed of a plurality of primary particles; wherein each primary particle is formed as a bundle of micro primary particles; wherein, when observed via a transmission electron microscope, the major axis direction of the micro primary particles coincides with the major axis direction of the primary particles; and wherein each micro primary particle has a thickness of about 1 nm to about 50 nm. ##STR00003##
2. The positive electrode active material of claim 1, wherein the primary particles have an average thickness of 0.4 m or less.
3. The positive electrode active material of claim 1, wherein, when observed via a transmission electron microscope to measure the average cross-sectional area of the primary particles, and when taking the square root of that average cross-sectional area, the primary particles have an average size of 0.5 m or less.
4. The positive electrode active material of claim 1, wherein a length-to-thickness ratio (aspect ratio) of the primary particles, obtained by dividing their length by their thickness, is between 5 and 100, inclusive.
5. The positive electrode active material of claim 1, wherein, defining a center point of an extension line as a midpoint between one end of the primary particle and an opposite end of the primary particle, an average of absolute values of acute angles is 20 or less, the acute angles being those formed between: (i) the extension line in the major axis direction that passes through the center of the primary particle, and (ii) an angle reference line connecting the center point of the extension line and the center of the secondary particle.
6. The positive electrode active material of claim 1, wherein the primary particles have an orientation distance of 2 m or less, the orientation distance being defined as an average distance between: (i) the extension line in the major axis direction that passes through the center of the primary particle, and (ii) a center reference line that is parallel to the extension line and passes through the center of the secondary particle.
7. The positive electrode active material of claim 1, wherein the precursor comprising the orientation-type primary particles formed of the micro primary particles exhibits, in XRD analysis, a (101) diffraction peak intensity that is higher than a (100) diffraction peak intensity.
8. The positive electrode active material of claim 1, wherein the primary particles include orientation-type particles having a rod shape with a minor axis and a major axis; wherein the orientation-type particles include an a-axis and a c-axis (the length in the a-axis direction being greater than the length in the c-axis direction); wherein the c-axis corresponds to the [001] direction in an SAED pattern obtained by observing the orientation-type particles via a transmission electron microscope; and wherein the a-axis is perpendicular to the c-axis and is arranged parallel to the major axis of the orientation-type particle.
9. The positive electrode active material of claim 1, wherein the secondary particle has an average diameter of about 2 m to about 20 m.
10. A method for producing a positive electrode active material for a secondary battery, the positive electrode active material comprising a composite metal hydroxide precursor represented by Chemical Formula 1 below: wherein the precursor includes a secondary particle composed of a plurality of primary particles, each primary particle is formed as a bundle of micro primary particles, when observed via a transmission electron microscope, the major axis direction of the micro primary particles coincides with the major axis direction of the primary particles, and each micro primary particle has a thickness of about 1 nm to about 50 nm, [Chemical Formula 1] (Ni.sub.xCo.sub.yMn.sub.1-x-y)(OH).sub.2 (0.40x0.96, 0y0.15), the method comprising: preparing a nickel compound including nickel (Ni), a cobalt compound including cobalt (Co), and a manganese compound including manganese (Mn), and mixing these compounds so that the molar ratio of nickel, cobalt, and manganese is x:y:(1xy); and performing a co-precipitation reaction in the presence of a first dopant, wherein the first dopant is at least one selected from the group consisting of Sb, Mo, W, Nb, Te, Ta, Zr, Ti, Sn, Y, In, Sr, Ba, Mg, Ca, B, V, Cr, Al, and Fe, and wherein an average concentration of the first dopant is from about 0.01 mol % to about 5 mol % based on the total moles of nickel, cobalt, and manganese.
11. The method of claim 10, wherein the co-precipitation process comprises: (a) introducing at least two or more types of a first dopant simultaneously to perform co-precipitation, thereby uniformly impregnating the precursor from the core to the surface (wet co-doping); or (b) during precursor synthesis, preventing the first dopant from being doped into the interior of the particle while impregnating the first dopant only within a region up to 2 m from the surface shell (wet shell doping); or (c) immediately after precursor formation, forming a coating layer of the first dopant only on the surface (hetero-element coating co-precipitation), wherein the positive electrode active material for the secondary battery is manufactured using any one of the above methods.
12. The method of claim 10, wherein the co-precipitation reaction includes a seed co-precipitation reaction, wherein the seed co-precipitation reaction comprises using at least one seed precursor selected from a composite metal hydroxide fine particle, a metal oxide, or a metal sulfide, each having an average diameter of about 0.5 m to about 3.5 m, and inducing an additional co-precipitation reaction on a surface of the seed precursor to promote secondary particle growth and formation of orientation-type particles.
13. The method of claim 10, wherein the co-precipitation reaction is carried out by using one or more heterogeneous element compound seeds selected from the group consisting of a composite metal hydroxide, a metal oxide, or a metal sulfide, each having an average particle diameter of 1 m or less, subjecting commercially available heterogeneous element compound seeds to ultrasonic treatment in advance so as to obtain heterogeneous element compound seeds having a D50 size of 1 m or less, adding the resulting heterogeneous element compound seeds into a reactor containing distilled water and stirring for a predetermined time, and thereafter continuously supplying a transition metal solution, an ammonia solution, and a caustic soda solution for the co-precipitation reaction into the reactor so as to newly form composite metal hydroxide precursor particles on surfaces of the heterogeneous element compound seed particles.
14. The method of claim 10, wherein at least a portion of the composite metal hydroxide precursor has a concentration gradient.
15. A method for producing a positive electrode active material for a secondary battery, the positive electrode active material comprising a composite metal hydroxide precursor represented by Chemical Formula 1 below: wherein the precursor includes a secondary particle composed of a plurality of primary particles, each primary particle is formed as a bundle of micro primary particles, when observed via a transmission electron microscope, the major axis direction of the micro primary particles coincides with the major axis direction of the primary particles, and each micro primary particle has a thickness of about 1 nm to about 50 nm, [Chemical Formula 1] (Ni.sub.xCo.sub.yMn.sub.1-x-y)(OH).sub.2 (0.40x0.96, 0y0.15), the method comprising: preparing a nickel compound including nickel (Ni), a cobalt compound including cobalt (Co), and a manganese compound including manganese (Mn), and mixing these compounds so that the molar ratio of nickel, cobalt, and manganese is x:y:(1xy); and performing a co-precipitation reaction in the presence of a first dopant, wherein the co-precipitation reaction in the reactor includes a solid-liquid synthesis step in which a solution remaining inside the reactor is removed to the outside of the reactor, and wherein orientation-type particles composed of micro primary particles are formed at a precursor concentration of at least about 0.2 kg of precursor per liter of solution.
16. The method of claim 15, wherein at least a portion of the composite metal hydroxide precursor has a concentration gradient.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the inventive concepts.
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DETAILED DESCRIPTION
[0137] In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of various embodiments or implementations of the invention. As used herein embodiments and implementations are interchangeable words that are non-limiting examples of devices or methods employing one or more of the inventive concepts disclosed herein. It is apparent, however, that various embodiments may be practiced without these specific details or with one or more equivalent arrangements. In other instances, well-known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring various embodiments. Further, various embodiments may be different, but do not have to be exclusive. For example, specific shapes, configurations, and characteristics of an embodiment may be used or implemented in another embodiment without departing from the inventive concepts.
[0138] Unless otherwise specified, the illustrated embodiments are to be understood as providing features of varying detail of some ways in which the inventive concepts may be implemented in practice. Therefore, unless otherwise specified, the features, components, modules, layers, films, panels, regions, and/or aspects, etc. (hereinafter individually or collectively referred to as elements), of the various embodiments may be otherwise combined, separated, interchanged, and/or rearranged without departing from the inventive concepts.
[0139] The use of cross-hatching and/or shading in the accompanying drawings is generally provided to clarify boundaries between adjacent elements. As such, neither the presence nor the absence of cross-hatching or shading conveys or indicates any preference or requirement for particular materials, material properties, dimensions, proportions, commonalities between illustrated elements, and/or any other characteristic, attribute, property, etc., of the elements, unless specified. Further, in the accompanying drawings, the size and relative sizes of elements may be exaggerated for clarity and/or descriptive purposes. When an embodiment may be implemented differently, a specific process order may be performed differently from the described order. For example, two consecutively described processes may be performed substantially at the same time or performed in an order opposite to the described order. Also, like reference numerals denote like elements.
[0140] When an element, such as a layer, is referred to as being on, connected to, or coupled to another element or layer, it may be directly on, connected to, or coupled to the other element or layer or intervening elements or layers may be present. When, however, an element or layer is referred to as being directly on, directly connected to, or directly coupled to another element or layer, there are no intervening elements or layers present. To this end, the term connected may refer to physical, electrical, and/or fluid connection, with or without intervening elements. Further, the D1-axis, the D2-axis, and the D3-axis are not limited to three axes of a rectangular coordinate system, such as the x, y, and z-axes, and may be interpreted in a broader sense. For example, the D1-axis, the D2-axis, and the D3-axis may be perpendicular to one another, or may represent different directions that are not perpendicular to one another. For the purposes of this disclosure, at least one of X, Y, and Z and at least one selected from the group consisting of X, Y, and Z may be construed as X only, Y only, Z only, or any combination of two or more of X, Y, and Z, such as, for instance, XYZ, XYY, YZ, and ZZ. As used herein, the term and/or includes any and all combinations of one or more of the associated listed items.
[0141] Although the terms first, second, etc. may be used herein to describe various types of elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another element. Thus, a first element discussed below could be termed a second element without departing from the teachings of the disclosure.
[0142] Spatially relative terms, such as beneath, below, under, lower, above, upper, over, higher, side (e.g., as in sidewall), and the like, may be used herein for descriptive purposes, and, thereby, to describe one elements relationship to another element(s) as illustrated in the drawings. Spatially relative terms are intended to encompass different orientations of an apparatus in use, operation, and/or manufacture in addition to the orientation depicted in the drawings. For example, if the apparatus in the drawings is turned over, elements described as below or beneath other elements or features would then be oriented above the other elements or features. Thus, the exemplary term below can encompass both an orientation of above and below. Furthermore, the apparatus may be otherwise oriented (e.g., rotated 90 degrees or at other orientations), and, as such, the spatially relative descriptors used herein interpreted accordingly.
[0143] The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting. As used herein, the singular forms, a, an, and the are intended to include the plural forms as well, unless the context clearly indicates otherwise. Moreover, the terms comprises, comprising, includes, and/or including, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It is also noted that, as used herein, the terms substantially, about, and other similar terms, are used as terms of approximation and not as terms of degree, and, as such, are utilized to account for inherent deviations in measured, calculated, and/or provided values that would be recognized by one of ordinary skill in the art.
[0144] Various embodiments are described herein with reference to sectional and/or exploded illustrations that are schematic illustrations of idealized embodiments and/or intermediate structures. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments disclosed herein should not necessarily be construed as limited to the particular illustrated shapes of regions, but are to include deviations in shapes that result from, for instance, manufacturing. In this manner, regions illustrated in the drawings may be schematic in nature and the shapes of these regions may not reflect actual shapes of regions of a device and, as such, are not necessarily intended to be limiting.
[0145] As customary in the field, some embodiments are described and illustrated in the accompanying drawings in terms of functional blocks, units, and/or modules. Those skilled in the art will appreciate that these blocks, units, and/or modules are physically implemented by electronic (or optical) circuits, such as logic circuits, discrete components, microprocessors, hard-wired circuits, memory elements, wiring connections, and the like, which may be formed using semiconductor-based fabrication techniques or other manufacturing technologies. In the case of the blocks, units, and/or modules being implemented by microprocessors or other similar hardware, they may be programmed and controlled using software (e.g., microcode) to perform various functions discussed herein and may optionally be driven by firmware and/or software. It is also contemplated that each block, unit, and/or module may be implemented by dedicated hardware, or as a combination of dedicated hardware to perform some functions and a processor (e.g., one or more programmed microprocessors and associated circuitry) to perform other functions. Also, each block, unit, and/or module of some embodiments may be physically separated into two or more interacting and discrete blocks, units, and/or modules without departing from the scope of the inventive concepts. Further, the blocks, units, and/or modules of some embodiments may be physically combined into more complex blocks, units, and/or modules without departing from the scope of the inventive concepts.
[0146] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure is a part. Terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and should not be interpreted in an idealized or overly formal sense, unless expressly so defined herein.
[0147] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the technical concept of the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced here are provided to ensure a thorough and complete disclosure and to fully convey the spirit of the invention to those skilled in the art.
[0148] In this specification, when an element is stated to be on another element, it may be directly formed on the other element, or there may be a third element interposed between them. Additionally, in the drawings, the thickness of films and regions is exaggerated for the effective explanation of the technical content.
[0149] Furthermore, in various embodiments of this specification, terms such as first, second, third, etc., are used to describe various elements, but these elements should not be limited by such terms. These terms are only used to distinguish one element from another. Therefore, an element referred to as a first element in one embodiment may be referred to as a second element in another embodiment. Each embodiment described and illustrated herein also includes its complementary embodiments. Moreover, the term and/or is used to mean that at least one of the listed elements is included.
[0150] The singular form used in this specification includes the plural form unless the context clearly indicates otherwise. Also, terms such as include or have are intended to indicate the presence of features, numbers, steps, elements, or combinations thereof described in the specification and should not be interpreted as excluding the possibility of the presence or addition of one or more other features, numbers, steps, elements, or combinations thereof.
[0151] Additionally, when describing the present invention, detailed descriptions of well-known functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the invention.
[0152] In the present invention, the term bundle has the same meaning as aggregation and is used interchangeably.
[0153]
[0154] Referring first to
[0155] As shown in the figures, the composite metal hydroxide precursor includes secondary particles (200) composed of clusters of multiple primary particles (100). The secondary particle (200) may include a central region (A) and a surface region (B). The primary particles (100) can include primary particles (110) located in the central region (A) of the secondary particle (200) and primary particles (120) located in the surface region (B) of the secondary particle (200). The primary particles (110) are arranged in the center of the secondary particle (200), while the primary particles (120) surround the primary particles (110) and are positioned at the surface region (B) of the secondary particle (200).
[0156] The primary particles (110) have an average major axis length a1 and an average minor axis length a2, perpendicular to a1, where a1 is equal to or greater than a2 (a1a2). Similarly, the primary particles (120) have an average major axis length b1 and an average minor axis length b2, perpendicular to b1, where b1 is greater than b2 (b1>b2).
[0157] The primary particles (120) may have a rod shape, where the cross-section consists of the major axis b1 and the perpendicular minor axis b2. At least some of the primary particles (120) may be radially aligned, meaning that their orientation follows direction R, extending from the center (C) of the secondary particle (200) to its outermost surface.
[0158] For example, the primary particles (120) are arranged such that their major axis is aligned parallel to the radial direction, which facilitates ion diffusion from the surface to the interior of the secondary particle (200). Additionally, the primary particles (120) can be aligned parallel to the direction of ion movement. By aligning the orientation of the primary particles (120) with the direction of ion movement, the volumetric expansion and contraction of the secondary particles (200) during the charge-discharge cycles of a secondary battery can be mitigated, thereby reducing cracks between the primary particles (100) caused by volumetric changes and improving the battery's cycle life.
[0159] For instance, in the secondary particle (200), the direction (R) extending from the center (C) to the surface is parallel to the a-axis direction of the primary particles (100), while the c-axis direction of the primary particles (100) is perpendicular to the a-axis direction.
[0160] Thus, in the embodiment of the present invention, the primary particles include oriented particles in a rod-shaped (rod-shape) form with major and minor axes. These oriented particles possess an a-axis and a c-axis, where the length along the a-axis is greater than that along the c-axis. The c-axis corresponds to the [001] direction observed in the SAED (Selected Area Electron Diffraction) pattern of the oriented particles using a transmission electron microscope, and the a-axis is perpendicular to the c-axis, being parallel to the major axis of the oriented particles.
[0161] Referring to
[0162] Referring to
[0163] In one embodiment of the present invention, the primary particles have an average thickness of 0.4 m or less. When observed using transmission electron microscopy, the square root of the primary particle's average cross-sectional area corresponds to an average size of 0.5 m or less.
[0164] The aspect ratio (length divided by thickness) of the primary particles may range from 5 to 100.
[0165] In this embodiment, if the extended center point of the primary particle is defined as the midpoint of its major axis, the acute angle between the extended centerline of the primary particle's major axis and a reference line connecting the extended center point to the secondary particle's center is 20 or less on average.
[0166] Additionally, the alignment distance, defined as the average distance between the extended centerline of the primary particle's major axis and a central reference line passing through the center of the secondary particle, is 2 m or less.
[0167] Furthermore, a precursor containing oriented primary particles made of fine primary particles exhibits a higher XRD intensity for the (101) diffraction plane than for the (100) diffraction plane.
[0168] Referring to
[0169] If b1/b2<1.5, voids may form between the secondary particles (200), making them prone to cracking along the center (C) of the secondary particles (200) after prolonged cycling. Conversely, if b1/b2>25, the primary particles (120) may become fragile and break easily under external forces. More specifically, the ratio of b1 to b2 may be 1.5 to 20, 1.5 to 15, 1.5 to 10, or 2 to 10.
[0170] The average length of b1 in the primary particles (120) is 2.0 m or less. If b1 exceeds 2.0 m, the cycle life characteristics of the secondary battery may degrade. Specifically, b1 may range from 0.005 to 2.0 m, 0.01 to 2.0 m, 0.05 to 2.0 m, 0.1 to 2.0 m, 0.05 to 1.5 m, 0.05 to 1.2 m, or 0.1 to 1.2 m.
[0171] The average length of b2 in the primary particles (120) may range from 0.1 m to 2.0 m. By controlling the lengths b1 and b2 within the specified ranges, the alignment of primary particles (120) forming the secondary particle (200) can be enhanced. Specifically, b2 may range from 0.015 to 0.8 m, 0.02 to 0.6 m, 0.03 to 0.5 m, or 0.03 to 0.25 m.
[0172] By optimizing b1 and b2, the alignment of primary particles (120) at the surface region (B) of the secondary particle (200) is improved, resulting in higher structural stability and denser packing, which prevents electrolyte penetration into the core region (A) of the secondary particle (200).
[0173] The cathode active material in this embodiment can be synthesized via a coprecipitation reaction using at least one transition metal compound with a composite metal hydroxide precursor. The highly oriented primary particles that form during the precursor stage remain intact even after high-temperature calcination, ensuring the preservation of the oriented structure in the final sintered cathode active material.
[0174] The average diameter of the secondary particles may range from 2 m to 20 m. If the diameter is less than 2 m, excessive electrolyte contact may accelerate degradation during battery cycling. If it exceeds 20 m, the volumetric energy density of the cathode may decrease.
[0175] These characteristics will be further detailed in the subsequent embodiments.
Comparative Example 1
[0176]
[0177] As shown in
[0178] Referring to
[0179] It can also be observed that the average orientation distance of the primary particles is as large as about 1.75 m. Furthermore, defining the center point of an extension line as the midpoint between one end of the primary particle and the other end, the average of the absolute values of the acute angles-formed between (i) the extension line in the major axis direction passing through the center of the primary particle, and (ii) an angle reference line connecting the center point of that extension line to the center of the secondary particle exceeds 20.
[0180] This indicates that, when a typical co-precipitation reaction is performed on the composite metal hydroxide precursor, micro primary particles do not form bundles and do not exhibit orientation.
[0181] Meanwhile, from the XRD analysis results in
[Comparative Example 2 and Example 1] [Ni.SUB.0.96.Co.SUB.0.02.Mn.SUB.0.02.](OH).SUB.2
[0182]
[0183]
[0184]
[0185] The first embodiment relates to a W-wet-doped [Ni.sub.0.96Co.sub.0.02Mn.sub.0.02](OH).sub.2 composite metal hydroxide precursor. As can be seen in the figures, bundles of micro primary particles are observed in the first embodiment. In
[0186] Meanwhile,
[0187] Referring to
[0188] Additionally, the average orientation distance of the primary particles in Example 1 is about 0.16 m, which is greatly reduced compared to Comparative Example 1. Thus, compared to the comparative examples, the micro primary particles in Example 1 clearly exhibit orientation and form bundles.
[0189] In the XRD analysis results shown in
[0190] Table 1 (
TABLE-US-00001 TABLE 1 Chemical composition (at %) Cathode Ni Co Mn W NCM960202 96.1 1.8 2.1 W-NCM960202 95.4 1.9 1.8 0.9
TABLE-US-00002 TABLE 2 0.1 C Disch. 0.2 C 0.5 C 0.5 C Precusor Capa Capacity 0.2 C/ Capacity 0.5 C/ Cycle Cathode systhesis (mAh/g) Efficiency (mAh/g) 0.1 C (mAh/g) 0.1 C Cycle Retention NCM960202 General co- 237.7 94.6% 233.2 98.1% 223.2 93.9% 100 81.5% precipitation W- W wet 238.5 92.7% 233.8 98.0% 224.6 94.1% 100 90.4% NCM960202 doping
TABLE-US-00003 TABLE 3 0.2 C 0.5 C 1 C 2 C 5 C 10 C Precusor Capacity Capacity Capacity Capacity Capacity Capacity Cathode systhesis (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g) NCM960202 General co- 233.8 226.8 218.8 204.7 183.1 170.9 precipitation W- W wet 233.4 228.7 221.4 210.2 190.1 182.2 NCM960202 doping
[0191] In Comparative Example 2 (shown in Tables 1 to 3), a typical co-precipitation reaction was performed. Compared to that, in Example 1, there is no significant difference in the initial capacity (0.1C) or the capacity at high-rate charge/discharge (0.2C, 0.5C). However, the capacity retention rate (at 0.5C, 100 cycles) in Example 1 is markedly higher than that in Comparative Example 2. This indicates that the orientation-type particles formed by W wet doping significantly enhance the crystal structural stability of the precursor, thereby greatly improving the cycle life characteristics.
[0192]
[0193]
[Comparative Example 3 and Example 2] [Ni.SUB.0.94.Co.SUB.0.04.Mn.SUB.0.02.](OH).SUB.2
[0194]
[0195]
[0196]
[0197] The second embodiment of the present invention relates to an Sb-wet-doped [Ni.sub.0.94Co.sub.0.04Mn.sub.0.02](OH).sub.2 composite metal hydroxide precursor. As shown in the figures, bundles of micro primary particles are observed in Example 2. In addition, Example 2 demonstrates that orientation-type particles appear not only at the extreme surface of the secondary particles but also in the shell region thereof.
[0198] Meanwhile,
[0199] By examining these figures, it is possible to determine the thickness, length, aspect ratio, size, angle, and orientation distance of the primary particles in Example 2. More specifically, one can ascertain the particle size (length/width) and aspect ratio, quantitatively analyze the orientation (degree of orientation) of the particles, and confirm their spatial distribution relative to the central axis. In Example 2, the aspect ratio is about 53.6, and it is apparent that the distribution of the primary particles exhibits an orientation.
[0200] Furthermore, the average orientation distance of the primary particles is about 0.12 m, which is significantly smaller compared to that of Comparative Example 1. In Example 2, the micro primary particles exhibit a marked degree of orientation and form bundles, in clear contrast to Comparative Example 1.
[0201] Table 4 compares the chemical compositions of the positive electrode active materials of Comparative Example 3 and Example 2 of the present invention.
[0202] Table 5 compares the electrochemical performance (capacity, rate capability, and cycle life) of Comparative Example 3 and Example 2.
[0203] Table 6 specifically focuses on comparing the rate capabilities in the electrochemical performance of Comparative Example 3 and Example 2.
TABLE-US-00004 TABLE 4 Chemical composition (at %) Cathode Ni Co Mn Sb NCM940402 94.0 4.2 1.8 Sb-NCM940402 93.4 3.9 1.9 0.8
TABLE-US-00005 TABLE 5 0.1 C Disch. 0.2 C 0.5 C 0.5 C Precusor Capa Capacity 0.2 C/ Capacity 0.5 C/ Cycle Cathode systhesis (mAh/g) Efficiency (mAh/g) 0.1 C (mAh/g) 0.1 C Cycle Retention NCM940402 General co- 238.9 96.3% 230.1 97.1% 221.01 89.1% 100 83.1% precipitation Sb- Sb wet 240.7 97% 233.5 97.7% 227.08 91.5% 100 93.9% NCM940402 doping
TABLE-US-00006 TABLE 6 0.2 C 0.5 C 1 C 2 C 5 C 10 C Precusor Capacity Capacity Capacity Capacity Capacity Capacity Cathode systhesis (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g) NCM940402 General 230.0 221.9 214.2 202.6 181.4 164.2 co- precipitation Sb- Sb wet 233.4 228.1 222.3 214.2 192.7 175.3 NCM940402 doping
[0204] In Comparative Example 3 (as shown in Tables 4 to 6), a typical co-precipitation reaction was performed. Compared to that, in Example 2, although there is no significant difference in initial capacity (0.1C) or high-rate charge/discharge capacity (0.2C, 0.5C), the capacity retention (at 0.5C, 100 cycles) in Example 2 is markedly higher than that in Comparative Example 3. This indicates that, through the Sb-wet-doped co-precipitation reaction, the presence of orientation-type particles increases the crystal structural stability of the precursor, thereby significantly improving the cycle life characteristics.
[0205]
[Comparative Example 3 and Example 3] [Ni.SUB.0.94.Co.SUB.0.04.Mn.SUB.0.02.](OH).SUB.2
[0206]
[0207]
[0208]
[0209] The third embodiment of the present invention relates to an Sb- and Ti-wet-doped [Ni.sub.0.94Co.sub.0.04Mn.sub.0.02](OH).sub.2 composite metal hydroxide precursor. Referring to
[0210] As shown in
[0211]
[0212]
[0213]
[0214] From these figures, one can determine the thickness, length, aspect ratio, size, angle, and orientation distance of the primary particles in Example 3. That is, the particle size (length/width) and aspect ratio can be evaluated, the orientation (degree of alignment) of the particles can be quantitatively analyzed, and the spatial distribution of how the particles are positioned relative to their central axis can be confirmed. In Example 3, the aspect ratio is about 55.4, and the primary particles exhibit an oriented distribution.
[0215] Moreover, the average orientation distance of the primary particles is about 0.11 m, which is significantly reduced compared to Comparative Example 1. Therefore, in Example 3, the micro primary particles clearly exhibit orientation and form bundles, in sharp contrast to Comparative Example 1.
[0216] From the XRD analysis results shown in
[0217] Meanwhile, Table 7 compares the chemical compositions of the positive electrode active materials of Comparative Example 3 and Example 3 of the present invention.
[0218] Table 8 compares their electrochemical performance (capacity, rate capability, cycle life).
[0219] Table 9 presents a more focused comparison on rate capability among their electrochemical performance.
TABLE-US-00007 TABLE 7 Chemical composition (at %) Cathode Ni Co Mn Sb Ti NCM940402 94.0 4.2 1.8 Sb, Ti-NCM940402 93.1 3.8 1.8 0.8 0.5
TABLE-US-00008 TABLE 8 0.1 C Disch. 0.2 C 0.5 C 0.5 C Precusor Capa Capacity 0.2 C/ Capacity 0.5 C/ Cycle Cathode systhesis (mAh/g) Efficiency (mAh/g) 0.1 C (mAh/g) 0.1 C Cycle Retention NCM940402 General 238.9 96.3% 230.1 97.1% 221.0 89.1% 100 83.1% co- precipitation Sb, Ti- Sb, Ti wet 240.7 96.7% 236.6 98.3% 226.3 94.0% 100 95.1% NCM940402 doping
TABLE-US-00009 TABLE 9 0.2 C 0.5 C 1 C 2 C 5 C 10 C Precusor Capacity Capacity Capacity Capacity Capacity Capacity Cathode systhesis (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g) NCM940402 General 230.0 221.9 214.2 202.6 181.4 164.2 co- precipitation Sb, Ti- Sb, Ti wet 235.5 226.7 221.0 210.3 186.8 179.3 NCM940402 doping
[0220] Based on Tables 7 to 9, although the co-precipitation reaction in Comparative Example 3 is a typical one, Example 3 exhibits improved initial capacity (at 0.1C) and high-rate charge/discharge capacity (at 0.2C and 0.5C), and especially demonstrates a markedly higher capacity retention (at 0.5C, 100 cycles) compared to Comparative Example 3. This indicates that, through co-precipitation involving Sb and Ti wet doping of the Ni.sub.0.94Co.sub.0.04Mn.sub.0.02](OH).sub.2 composite metal hydroxide precursor, orientation-type particles are formed that increase the stability of the precursor's crystal structure, thereby greatly improving the cycle life characteristics.
[0221]
[Comparative Example 4 and Example 4] [Ni.SUB.0.90.Co.SUB.0.05.Mn.SUB.0.05.](OH).SUB.2
[0222]
[0223]
[0224]
[0225] Referring to
[0226]
[0227] Further, referring to
[0228] In the fourth embodiment, the composite metal hydroxide precursor exhibits an aspect ratio of about 54.5, demonstrating that the primary particles are distributed in an oriented manner. Even in the fine-particle composite metal hydroxide precursor (D50: 1.5-3.5 m), which generally makes it difficult for orientation-type primary particles to develop, an aspect ratio of about 23.7 is observed, along with clear signs of orientation.
[0229] Moreover, the average orientation distance of the primary particles is approximately 0.11 m or 0.01 m, respectively significantly reduced compared to Comparative Example 1. Accordingly, in Example 4, the micro primary particles clearly exhibit strong orientation and form bundles, in contrast to the comparative examples.
[0230] Tables 10 and 11 compare the chemical compositions of the positive electrode active materials in Comparative Example 4 and Example 4 of the present invention, showing the compositions of both the composite metal hydroxide precursor and the fine-particle composite metal hydroxide precursor, respectively.
[0231] Tables 12 and 13 compare the electrochemical performance (capacity, rate characteristics, cycle life) of Comparative Example 4 and Example 4 of the present invention for both the composite metal hydroxide precursor and the fine-particle composite metal hydroxide precursor.
[0232] Tables 14 and 15 offer a more detailed comparison specifically focusing on rate characteristics among the electrochemical performance results of Comparative Example 4 and Example 4, for both the composite metal hydroxide precursor and the fine-particle composite metal hydroxide precursor.
TABLE-US-00010 TABLE 10 Chemical composition (at %) Cathode Ni Co Mn Mo NCM900505 89.8 5.1 5.1 Mo-NCM900505 89.6 4.9 4.8 0.7
TABLE-US-00011 TABLE 11 Chemical composition (at %) Cathode Ni Co Mn Mo NCM900505 89.8 5.1 5.1 Mo-NCM900505 89.5 4.8 4.8 0.9
TABLE-US-00012 TABLE 12 0.1 C Disch. 0.2 C 0.5 C 0.5 C Precusor Capa Capacity 0.2 C/ Capacity 0.5 C/ Cycle Cathode systhesis (mAh/g) Efficiency (mAh/g) 0.1 C (mAh/g) 0.1 C Cycle Retention NCM900505 General 232.9 95.5% 222.4 95.5% 215.3 92.4% 100 86.3% co- precipitation Mo- Mo wet 233.0 94.6% 225.9 97.0% 219.2 94.1% 100 94.1% NCM900505 doping
TABLE-US-00013 TABLE 13 0.1 C Disch. 0.2 C 0.5 C 0.5 C Precusor Capa Capacity 0.2 C/ Capacity 0.5 C/ Cycle Cathode systhesis (mAh/g) Efficiency (mAh/g) 0.1 C (mAh/g) 0.1 C Cycle Retention NCM900505 General 232.9 95.5% 222.4 95.5% 215.3 92.4% 100 86.3% co- precipitation Mo- Mo wet 233.4 94.8% 226.2 96.9% 219.4 94.0% 100 92.7% NCM900505 doping
TABLE-US-00014 TABLE 14 0.2 C 0.5 C 1 C 2 C 5 C 10 C Precusor Capacity Capacity Capacity Capacity Capacity Capacity Cathode systhesis (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g) NCM900505 General 221.9 215.4 209.8 199.7 176.4 161.2 co-precipitation Mo- Mo wet doping 225.8 219.1 215.3 207.3 185.4 172.3 NCM900505
TABLE-US-00015 TABLE 15 0.2 C 0.5 C 1 C 2 C 5 C 10 C Precusor Capacity Capacity Capacity Capacity Capacity Capacity Cathode systhesis (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g) NCM900505 General 221.9 215.4 209.8 199.7 176.4 161.2 co- precipitation Mo- Mo wet 226.1 219.5 215.2 208.1 186.1 173.1 NCM900505 doping
[0233] When comparing Comparative Example 4, which employed a typical co-precipitation reaction, to Example 4, it is evident from Tables 10 to 15 that Example 4 achieves more favorable performance in initial capacity (0.1C) and high-rate charge/discharge capacity (0.2C, 0.5C). In particular, Example 4 demonstrates a markedly higher capacity retention (0.5C, 100 cycles) compared to Comparative Example 4. This indicates that, in the composite metal hydroxide precursor of Example 4, the formation of orientation-type particles via the co-precipitation reaction enhances the crystal structural stability of the precursor, resulting in significantly improved cycle life characteristics.
[0234] Moreover, this effect is also observed in fine-particle composite metal hydroxide precursors (D50: 1.5-3.5 m), which typically present challenges for the development of orientation-type primary particles. Despite such challenges, these fine particles similarly exhibit orientation, thereby increasing the structural stability of the precursor and achieving remarkably improved cycle life characteristics.
[Comparative Example 5 and Example 5] [Ni.SUB.0.90.Co.SUB.0.05.Mn.SUB.0.05.](OH).SUB.2
[0235]
[0236]
[0237] In the fifth embodiment, tungsten (W) is wet-doped into the shell surface of the [Ni.sub.0.90Co.sub.0.05Mn.sub.0.05](OH).sub.2 composite metal hydroxide precursor, forming primary particles composed of bundles of micro primary particles. It can also be seen that the micro primary particles have a thickness of about 1-50 nm.
[0238] Referring to
[0239]
[0240] From these figures, one can determine the thickness, length, aspect ratio, size, angles, orientation distance, and other characteristics of the primary particles in Example 5.
[0241] Specifically, it is possible to ascertain the particle size (length/width) and aspect ratio, quantitatively analyze the orientation (degree of alignment), and confirm the spatial distribution of how particles are situated relative to their central axis. In Example 5, the aspect ratio is about 58, indicating that the primary particles exhibit an oriented distribution.
[0242] Additionally, the average orientation distance of the primary particles is about 0.12 m, showing a significant reduction compared to Comparative Example 1. Thus, in Example 5, it is clear that the micro primary particles exhibit a strong degree of orientation and form bundles, in sharp contrast to Comparative Example 1.
[0243] Meanwhile, Table 16 compares the chemical compositions of the positive electrode active materials of Comparative Example 5 and Example 5.
[0244] Table 17 compares their electrochemical performance (capacity, rate capability, cycle life).
[0245] Table 18 presents a more detailed comparison of their electrochemical performance with an emphasis on rate capability.
TABLE-US-00016 TABLE 16 Chemical composition (at %) Cathode Ni Co Mn W NCM900505 89.8 5.1 5.1 W shell-NCM900505 89.7 4.9 4.9 0.5
TABLE-US-00017 TABLE 17 0.1 C Disch. 0.2 C 0.5 C 0.5 C Precusor Capa Capacity 0.2 C/ Capacity 0.5 C/ Cycle Cathode systhesis (mAh/g) Efficiency (mAh/g) 0.1 C (mAh/g) 0.1 C Cycle Retention NCM900505 General 232.9 95.5% 222.4 95.5% 215.3 92.4% 100 86.3% co- precipitation W shell- W wet shell 233.2 96.7% 224.9 96.4% 218.2 93.6% 100 93.8% NCM900505 doping
TABLE-US-00018 TABLE 18 0.2 C 0.5 C 1 C 2 C 5 C 10 C Precusor Capacity Capacity Capacity Capacity Capacity Capacity Cathode systhesis (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g)) (mAh/g) NCM900505 General 221.9 215.4 209.8 199.7 176.4 161.2 co- precipitation W shell- W wet shell 222.9 218.1 214.4 204.2 180.9 169.1 NCM900505 doping
[0246] In Comparative Example 5, a typical co-precipitation reaction was carried out. By contrast, in Example 5, although there is no substantial difference in initial capacity (0.1C) or high-rate charge/discharge capacity (0.2C, 0.5C) compared to Comparative Example 5, the capacity retention (at 0.5C, 100 cycles) is markedly higher in Example 5. This result demonstrates that, through the co-precipitation reaction in the composite metal hydroxide precursor of Example 5, orientation-type particles are formed, significantly enhancing the crystal structural stability of the precursor and thereby greatly improving its cycle life characteristics.
[0247] Meanwhile,
[Comparative Example 5 and Example 6] [Ni.SUB.0.90.Co.SUB.0.05.Mn.SUB.0.05.](OH).SUB.2
[0248]
[0249]
[0250] In the sixth embodiment, the [Ni.sub.0.90Co.sub.0.05Mn.sub.0.05](OH).sub.2 composite metal hydroxide precursor is prepared using an aluminum (Al) seed. Referring to
[0251] Moreover, orientation-type particles are observed not only in the primary particleswhich are formed from bundles of micro primary particlesbut also in the interior of the secondary particles, which comprise multiple primary particles. In other words, each primary particle is formed from bundles of micro primary particles, the major axis of the micro primary particles coincides with that of the primary particle, and the secondary particle composed of a plurality of such primary particles exhibits an oriented structure.
[0252]
[0253] Referring to these figures, one can determine the thickness, length, aspect ratio, size, angle, orientation distance, and so forth of the primary particles in Example 6. Specifically, the particle size (length/width) and aspect ratio can be ascertained, the orientation (degree of alignment) of the particles can be quantitatively analyzed, and the spatial distribution of how they are situated relative to their central axis can be confirmed. In Example 6, the aspect ratio is about 53.1, indicating that the primary particles display an oriented distribution.
[0254] Additionally, the average orientation distance of the primary particles is around 0.12 m, which is significantly smaller compared to Comparative Example 1. Hence, in Example 6, the micro primary particles are clearly oriented and form bundles, in stark contrast to Comparative Example 1.
[0255]
[0256] Meanwhile, Table 19 compares the chemical compositions of the positive electrode active materials according to Comparative Example 5 and Example 6 of the present invention.
[0257] Table 20 compares their electrochemical performance (capacity, rate capability, cycle life).
[0258] Table 21 provides a more focused comparison of their electrochemical performance, particularly with respect to rate capability.
TABLE-US-00019 TABLE 19 Chemical composition (at %) Cathode Ni Co Mn Al NCM900505 89.8 5.1 5.1 Al seed-NCM900505 89.9 5.0 4.9 0.2
TABLE-US-00020 TABLE 20 0.1 C Disch. 0.2 C 0.5 C 0.5 C Precusor Capa Capacity 0.2 C/ Capacity 0.5 C/ Cycle Cathode systhesis (mAh/g) Efficiency (mAh/g) 0.1 C (mAh/g) 0.1 C Cycle Retention NCM900505 General 232.9 95.5% 222.4 95.5% 215.3 92.4% 100 86.3% co- precipitation Al seed- Al seed co- 233.7 96.1% 224.1 95.9% 217.3 93.0% 100 89.9% NCM900505 precipitation
TABLE-US-00021 TABLE 21 0.2 C 0.5 C 1 C 2 C 5 C 10 C Precusor Capacity Capacity Capacity Capacity Capacity Capacity Cathode systhesis (mAh/g) (mAh/g) (mAh/g)) (mAh/g) (mAh/g) (mAh/g) NCM900505 General 221.9 215.4 209.8 199.7 176.4 161.2 co-precipitation Al seed- Al seed co- 223.9 218.4 212.3 204.3 182.4 168.7 NCM900505 precipitation
[0259] In Comparative Example 5, a typical co-precipitation reaction was performed. By contrast, although there is no substantial difference between Comparative Example 5 and Example 6 in terms of initial capacity (0.1C) or high-rate charge/discharge capacity (0.2C, 0.5C), the capacity retention (at 0.5C, 100 cycles) in Example 6 is markedly higher than in Comparative Example 5. This demonstrates that, in the composite metal hydroxide precursor of Example 6, the formation of orientation-type particles via the co-precipitation reaction greatly enhances the crystal structural stability of the precursor, leading to significantly improved cycle life characteristics.
[0260] Meanwhile,
Comparative Example 6
[0261]
[0262]
[0263]
[0264]
[0265] As shown in
[0266] Referring to
[0267] This indicates that, when a general co-precipitation reaction is performed on a composite metal hydroxide precursor, the micro primary particles do not form bundles and exhibit no orientation.
[0268] Meanwhile, the XRD analysis results in
[0269] Thus, under typical co-precipitation conditions, the particles in Comparative Example 6 exhibit decreased density and do not form bundles of micro primary particles, leading to a precursor that does not contain orientation-type particles.
[Comparative Example 7 and Example 7] [Ni.SUB.0.90.Co.SUB.0.10.](OH).SUB.2
[0270]
[0271] In the seventh embodiment, boron (B) is wet-doped into the [Ni.sub.0.90Co.sub.0.10](OH).sub.2 composite metal hydroxide precursor. Referring to
[0272] Moreover, orientation-type particles are observed not only in the primary particleseach formed from bundles of micro primary particlesbut also in the interior of the secondary particles, which are composed of multiple primary particles. Thus, each primary particle consists of bundles of micro primary particles, with the major axis direction of the micro primary particles coinciding with that of the primary particle, and the secondary particles, formed from these primary particles, exhibit a high degree of orientation.
[0273]
[0274] From these figures, one can determine the thickness, length, aspect ratio, size, angle, orientation distance, and so forth of the primary particles in Example 7. Specifically, one can evaluate the particle size (length/width) and aspect ratio, quantitatively analyze the orientation (degree of alignment) of the particles, and confirm how the particles are spatially distributed relative to their central axis. In Example 7, the aspect ratio is about 52.8, indicating that the primary particles exhibit an oriented distribution.
[0275] Additionally, the average orientation distance of the primary particles is about 0.07 m, which is significantly smaller compared to Comparative Example 1. Hence, in Example 7, the micro primary particles clearly exhibit orientation and form bundles, in marked contrast to Comparative Example 1.
[0276]
[0277] Meanwhile, Table 22 compares the chemical compositions of the positive electrode active materials from Comparative Example 7 and Example 7.
[0278] Table 23 compares their electrochemical performance (capacity, rate capability, cycle life).
[0279] Table 24 provides a more focused comparison of their electrochemical performance, particularly centered on rate capability.
TABLE-US-00022 TABLE 22 Chemical composition (at %) Cathode Ni Co B NC90 90.3 9.7 B-NC90 90.2 9.9 0.9
TABLE-US-00023 TABLE 23 0.1 C Disch. 0.2 C 0.5 C 0.5 C Precusor Capa Capacity 0.2 C/ Capacity 0.5 C/ Cycle Cathode systhesis (mAh/g) Efficiency (mAh/g) 0.1 C (mAh/g) 0.1 C Cycle Retention NC90 General 229.7 96.8% 225.4 98.1% 217.2 94.6% 100 80.3% co- precipitation B- B wet doping 230.8 95.5% 226.3 98.1% 218.1 94.5% 100 90.9% NC90
TABLE-US-00024 TABLE 24 0.2 C 0.5 C 1 C 2 C 5 C 10 C Precusor Capacity Capacity Capacity Capacity Capacity Capacity Cathode systhesis (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g)) (mAh/g) NC90 General 226.2 218.1 211.8 198.3 173.7 161.4 co- precipitation B- B wet doping 227.1 219.2 213.8 204.3 178.8 167.3 NC90
[0280] In Comparative Example 7, a typical co-precipitation reaction was performed. Compared to that, although there is no substantial difference between Comparative Example 7 and Example 7 in terms of initial capacity (0.1C) or high-rate charge/discharge capacity (0.2C, 0.5C), the capacity retention (at 0.5C, 100 cycles) in Example 7 is markedly higher than in Comparative Example 7. This indicates that, through the co-precipitation reaction employed in Example 7, orientation-type particles are formed in the composite metal hydroxide precursor, which significantly enhances the crystal structural stability of the precursor and thus improves its cycle life characteristics.
[0281] Meanwhile,
[Comparative Example 8 and Example 8] [Ni.SUB.0.90.Co.SUB.0.10.](OH).SUB.2
[0282]
[0283] In the eighth embodiment, the [Ni.sub.0.90Co.sub.0.10](OH).sub.2 composite metal hydroxide precursor is wet-doped with niobium (Nb). As seen in
[0284] Additionally, orientation-type particles are observed not only in the primary particleseach consisting of bundles of micro primary particlesbut also within the secondary particles that comprise multiple primary particles. In other words, each primary particle is formed from bundles of micro primary particles, the major axis of the micro primary particles aligns with that of the primary particle, and the secondary particles, which are made up of these primary particles, exhibit a high degree of orientation.
[0285]
[0286] Referring to these figures, one can determine the thickness, length, aspect ratio, size, angle, orientation distance, and other characteristics of the primary particles in Example 8. Specifically, the particle size (length/width) and aspect ratio can be identified, the orientation (degree of alignment) of the particles can be quantitatively analyzed, and the spatial distribution of how the particles are positioned relative to their central axis can be confirmed. In Example 8, the aspect ratio is about 57.5, indicating that the primary particles exhibit an oriented distribution.
[0287] Moreover, the average orientation distance of the primary particles is about 0.13 m, which is significantly smaller compared to Comparative Example 1. Hence, in Example 8, the micro primary particles clearly exhibit orientation and form bundles, in distinct contrast to Comparative Example 1.
[0288]
[0289] Meanwhile, Table 25 compares the chemical compositions of the positive electrode active materials of Comparative Example 8 and Example 8 of the present invention.
[0290] Table 26 compares their electrochemical performance (capacity, rate capability, and cycle life).
[0291] Table 27 presents a more focused comparison of their electrochemical performance, particularly centered on rate capability.
TABLE-US-00025 TABLE 25 Chemical composition (at %) Cathode Ni Co Al Nb NCA90 89.7 8.8 1.5 Nb coated-NCA90 89.5 8.8 1.3 0.4
TABLE-US-00026 TABLE 26 0.1 C Disch. 0.2 C 0.5 C 0.5 C Precusor Capa Capacity 0.2 C/ Capacity 0.5 C/ Cycle Cathode systhesis (mAh/g) Efficiency (mAh/g) 0.1 C (mAh/g) 0.1 C Cycle Retention NCA90 General 228.6 96.4% 224.2 98.1% 215.7 94.4% 100 83.7% co- precipitation Nb coated- Nb wet 229.4 96.2% 225.7 98.4% 217.2 94.7% 100 92.1% NCA90 surface coating
TABLE-US-00027 TABLE 27 0.2 C 0.5 C 1 C 2 C 5 C 10 C Precusor Capacity Capacity Capacity Capacity Capacity Capacity Cathode systhesis (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g) NCA90 General 225.1 217.6 210.9 197.4 172.1 159.5 co- precipitation Nb coated- Nb wet 227.0 219.4 212.9 205.1 179.2 169.4 NCA90 surface coating
[0292] In Comparative Example 8, a typical co-precipitation reaction was performed. By contrast, in Example 8, although there is no marked difference in initial capacity (0.1C) or high-rate charge/discharge capacity (0.2C, 0.5C) compared to Comparative Example 8, the capacity retention after cycling (0.5C, 100 cycles) is noticeably higher in Example 8. This indicates that, through the co-precipitation process in Example 8, orientation-type particles are formed in the composite metal hydroxide precursor, significantly improving the crystal structural stability of the precursor and thus markedly enhancing its cycle life characteristics.
[0293] Meanwhile, as shown in
[Comparative Example 9] [Ni.SUB.0.90.Mn.SUB.0.10.](OH).SUB.2
[0294]
[0295]
[0296]
[0297]
[0298] As shown in
[0299] Referring to
[0300] Moreover, when the solid-liquid synthesis (high slurry concentration) is not sufficiently highe.g., about 0.15 kg of precursor per liter of solutionmicro primary particles fail to bundle together and form orientation-type particles effectively. Therefore, raising the slurry concentration or adjusting the microstructure via doping with foreign elements or a seed co-precipitation method is necessary to achieve orientation.
[0301] Hence, under a typical co-precipitation reaction, the micro primary particles do not form bundles and exhibit no orientation in the composite metal hydroxide precursor.
[0302] Meanwhile, from the XRD analysis results shown in
[0303] Thus, in Comparative Example 9, a typical co-precipitation reaction leads to low-density particles and no bundle formation by micro primary particles. As a result, the composite metal hydroxide precursor in Comparative Example 9 forms no orientation-type particles and does not comprise bundles of micro primary particles.
[Comparative Example 10 and Example 9] [Ni.SUB.0.90.Mn.SUB.0.10.](OH).SUB.2
[0304]
[0305]
[0306]
[0307] In the ninth embodiment of the present invention, a Highly concentrated co-precipitation reaction is performed on the [Ni.sub.0.90Mn.sub.0.10](OH).sub.2 composite metal hydroxide precursor. Referring to
[0308] Furthermore, orientation-type particles are observed not only in the primary particleseach formed by bundles of micro primary particlesbut also within the secondary particles, which comprise multiple primary particles. In other words, each primary particle is made up of bundles of micro primary particles, the major axis direction of the micro primary particles aligns with that of the primary particle, and the secondary particles composed of these primary particles exhibit orientation.
[0309] Referring to
[0310]
[0311]
[0312] From these figures, one can confirm the thickness, length, aspect ratio, size, angle, orientation distance, etc. of the primary particles in Example 9. In other words, by examining the particle size (length/width) and aspect ratio, quantitatively analyzing the orientation (degree of alignment), and identifying how the particles are spatially arranged relative to their central axis, one can see that Example 9 has an aspect ratio of about 60.8, with the primary particles distributed in an oriented manner.
[0313] In addition, the average orientation distance of the primary particles is about 0.12 m, which is significantly smaller compared to the comparative example, indicating that the micro primary particles in Example 9 show a high degree of orientation and form bundles. According to the XRD analysis results in
[0314]
[0315] Meanwhile, Table 28 compares the chemical compositions of the positive electrode active materials obtained according to Comparative Example 10 and Example 9 of the present invention.
[0316] Table 29 compares their electrochemical performance (capacity, rate capability, and cycle life).
[0317] Table 30 presents a more detailed comparison of their electrochemical performance, focusing particularly on rate capability.
TABLE-US-00028 TABLE 28 Chemical composition (at %) Cathode Ni Mn Non-oriented NM90 89.9 10.1 Highly concentrated 90.1 9.9 Co-precipitation NM90
TABLE-US-00029 TABLE 29 0.1 C Disch. 0.2C 0.5C 0.5C Precusor Capa Capacity 0.2C/ Capacity 0.5C/ Cycle Cathode systhesis (mAh/g) Efficiency (mAh/g) 0.1C (mAh/g) 0.1C Cycle Retention Non-oriented General 230.4 94.9% 223.1 96.7% 214.1 94.2% 100 88.4% NM90 co- precipitation Highly Highly 231.4 96.9% 223.1 96.5% 218.5 94.5% 100 92.1% concentrated concentrated Co- Co- precipitation precipitation NM90
TABLE-US-00030 TABLE 30 0.2C 0.5C 1C 2C 5C 10C Precusor Capacity Capacity Capacity Capacity Capacity Capacity Cathode systhesis (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g)) Non-oriented General 224.1 213.3 208.1 195.4 170.7 158.8 NM90 co- precipitation Highly Highly 224.8 217.6 212.4 201.6 177.5 167.3 concentrated concentrated Co- Co- precipitation precipitation NM90
[0318] In Comparative Example 10, a typical co-precipitation reaction was carried out. By contrast, Example 9 shows a noticeable difference in the initial capacity (0.1C) and high-rate charge/discharge capacity (0.2C, 0.5C) compared to Comparative Example 10, and especially demonstrates a markedly higher capacity retention (at 0.5C, 100 cycles). This indicates that the formation of orientation-type particles in the composite metal hydroxide precursor of Example 9, achieved through a Highly concentrated co-precipitation reaction, significantly enhances the crystal structural stability of the precursor, thereby greatly improving its cycle life characteristics.
[0319] Meanwhile,
Comparative Example 11 and Example 10
[0320]
[0321]
[0322] In the tenth embodiment, the concentration-gradient [Ni.sub.0.90Mn.sub.0.10](OH).sub.2 composite metal hydroxide precursor is employed. As seen in the figures, Example 10 likewise exhibits a composite metal hydroxide precursor composed of bundles of micro primary particles, with each micro primary particle having a thickness of about 1-50 nm.
[0323] Moreover, orientation-type particles are observed not only in the primary particleseach formed by bundles of micro primary particlesbut also within the secondary particles that comprise multiple primary particles. In other words, each primary particle consists of bundles of micro primary particles, the major axis direction of the micro primary particles aligns with that of the primary particle, and the secondary particles, which are composed of these primary particles, exhibit an oriented structure.
[0324]
[0325] From these figures, one can determine the thickness, length, aspect ratio, size, angle, orientation distance, and so forth of the primary particles in Example 10. More specifically, the particle size (length/width) and aspect ratio can be assessed, the orientation (degree of alignment) of the particles can be quantitatively analyzed, and the spatial distribution of how the particles are situated with respect to their central axis can be verified. In Example 10, the aspect ratio is about 60.5, demonstrating that the primary particles have an oriented distribution.
[0326] Additionally, the average orientation distance of the primary particles is about 0.08 m, which is significantly reduced compared to the comparative example. Hence, in Example 10, the micro primary particles clearly exhibit orientation and form bundles, in stark contrast to the comparative example.
[0327]
[0328] Meanwhile, Table 31 compares the chemical compositions of the positive electrode active materials obtained from Comparative Example 11 and Example 10 of the present invention.
[0329] Table 32 compares their electrochemical performance (capacity, rate capability, cycle life).
[0330] Table 33 provides a more focused comparison of their electrochemical performance, particularly highlighting rate capability.
TABLE-US-00031 TABLE 31 Chemical composition (at %) Cathode Ni Mn NM90 89.9 10.1 Gradient NM90 89.8 10.2
TABLE-US-00032 TABLE 32 0.1 C Disch. 0.2C 0.5C 0.5C Precusor Capa Capacity 0.2C/ Capacity 0.5C/ Cycle Cathode systhesis (mAh/g) Efficiency (mAh/g) 0.1C (mAh/g) 0.1C Cycle Retention NM90 General 232.6 98.7% 227.0 97.6% 208.2 89.5% 100 80.7% co- precipitation Gradient Concentration 233.9 98.5% 228.2 97.6% 211.3 90.3% 100 92.0% NM90 gradient co- precipitation
TABLE-US-00033 TABLE 33 0.2C 0.5C 1C 2C 5C 10C Precusor Capacity Capacity Capacity Capacity Capacity Capacity Cathode systhesis (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g) NM90 General 224.1 213.3 208.1 195.4 170.7 158.8 co- precipitation Gradient Concentration 226.7 215.7 211.8 200.2 178.4 164.4 NM90 gradient co- precipitation
[0331] In Comparative Example 11, a typical co-precipitation reaction was carried out. By contrast, in Example 10, there is a noticeable difference in initial capacity (0.1C) and high-rate charge/discharge capacity (0.2C, 0.5C) compared to Comparative Example 11. In particular, the capacity retention (at 0.5C, 100 cycles) in Example 10 is markedly higher than that in Comparative Example 11. This indicates that, through the co-precipitation reaction in the composite metal hydroxide precursor of Example 10, orientation-type particles are formed, significantly enhancing the crystal structural stability of the precursor and thus greatly improving its cycle life characteristics.
[0332] Meanwhile,
[Comparative Example 12] [Ni.SUB.0.70.Co.SUB.0.10.Mn.SUB.0.20.](OH).SUB.2
[0333]
[0334]
[0335]
[0336] As shown in
[0337] Referring to
[0338] Thus, when a typical co-precipitation reaction is conducted on this composite metal hydroxide precursor, the micro primary particles do not form bundles and do not show any orientation.
[0339] Meanwhile, the XRD analysis results in
[0340] Hence, under standard co-precipitation conditions, [Ni.sub.0.70Co.sub.0.10Mn.sub.0.20](OH).sub.2 composite metal hydroxide precursor of Comparative Example 12 exhibits low particle density, lacks bundles of micro primary particles, and does not form orientation-type particles.
[0341] [Comparative Example 13 and Example 11]\
[0342]
[0343] In the eleventh embodiment, the [Ni.sub.0.70Co.sub.0.10Mn.sub.0.20](OH).sub.2 composite metal hydroxide precursor is wet-doped with tungsten (W). As shown in these figures, Example 11 also exhibits a composite metal hydroxide precursor composed of bundles of micro primary particles, each having a thickness of about 1-50 nm.
[0344] Moreover, orientation-type particles are observed not only in the primary particles each of which is formed by bundles of micro primary particlesbut also within the secondary particles, which consist of multiple primary particles. In other words, each primary particle is formed from bundles of micro primary particles, the major axis direction of the micro primary particles coincides with that of the primary particle, and the secondary particles (composed of these primary particles) exhibit orientation.
[0345]
[0346] Referring to these figures, one can determine the thickness, length, aspect ratio, size, angle, orientation distance, etc., of the primary particles in Example 11. In particular, the particle size (length/width) and aspect ratio can be quantified, the orientation (degree of alignment) of the particles can be analyzed, and the spatial distribution of how the particles are situated relative to their central axis can be confirmed. In Example 11, the aspect ratio is about 57.3, indicating that the primary particles exhibit an oriented distribution.
[0347] Furthermore, the average orientation distance of the primary particles is around 0.13 m, a significant reduction compared to the comparative example, clearly indicating that the micro primary particles in Example 11 are strongly oriented and form bundles.
[0348] Referring to
[0349] Meanwhile, Table 34 compares the chemical compositions of the positive electrode active materials according to Comparative Example 13 and Example 11 of the present invention. [0350] Table 35 compares their electrochemical performance (capacity, rate capability, and cycle life). [0351] Table 36 provides a more focused comparison of their electrochemical performance, particularly centered on rate capability.
TABLE-US-00034 TABLE 34 Chemical composition (at %) Cathode Ni Co Mn W NCM712 70.8 9.8 19.4 W-NCM712 70.6 9.6 19.4 0.4
TABLE-US-00035 TABLE 35 0.1 C Disch. 0.2C 0.5C 0.5C Precusor Capa Capacity 0.2C/ Capacity 0.5C/ Cycle Cathode systhesis (mAh/g) Efficiency (mAh/g) 0.1C (mAh/g) 0.1C Cycle Retention NCM712 General 220.7 95.7% 212.7 96.4% 201.3 91.2% 100 85.7% co- precipitation W- W wet 221.9 96.1% 214.5 96.7% 203.7 91.8% 100 91.3% NCM712 doping
TABLE-US-00036 TABLE 36 0.2C 0.5C 1C 2C 5C 10C Precusor Capacity Capacity Capacity Capacity Capacity Capacity Cathode systhesis (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g) NCM712 General 211.8 202.4 194.3 184.3 161.4 154.0 co- precipitation W- W wet doping 213.6 205.7 196.5 188.9 167.2 159.3 NCM712
[0352] In Comparative Example 13, a typical co-precipitation reaction was conducted. By contrast, Example 11 shows a notable difference in initial capacity (0.1C) and high-rate charge/discharge capacity (0.2C, 0.5C), and especially a markedly higher capacity retention (at 0.5C, 100 cycles) compared to Comparative Example 13. This indicates that, in the composite metal hydroxide precursor of Example 11, the formation of orientation-type particles via the co-precipitation reaction significantly enhances the crystal structural stability, resulting in a greatly improved cycle life.
[0353] Meanwhile,
[0354]
Comparative Example 14
[0355]
[0356]
[0357]
[0358] As shown in
[0359] Referring to
[0360] Hence, under standard co-precipitation conditions, the micro primary particles do not form bundles and do not exhibit orientation in this composite metal hydroxide precursor.
[0361] Meanwhile, from the XRD analysis results shown in
[0362] Thus, in Comparative Example 14, the precursor exhibits low particle density, no bundling of micro primary particles, and no formation of orientation-type particles under typical co-precipitation reaction conditions.
Comparative Example 14 and Example 12
[0363]
[0364]
[0365] In Example 12, a Highly concentrated co-precipitation reaction is performed on the Ni.sub.0.46Co.sub.0.08Mn.sub.0.46](OH).sub.2 composite metal hydroxide precursor. As shown in the figures, Example 12 similarly exhibits a composite metal hydroxide precursor composed of bundles of micro primary particles, each having a thickness of approximately 1-50 nm.
[0366] Moreover, orientation-type particles are observed not only in the primary particleseach one formed from bundles of micro primary particlesbut also within the secondary particles, which comprise multiple primary particles. In other words, each primary particle is formed from bundles of micro primary particles, the major axis of the micro primary particles aligns with that of the primary particle, and the secondary particles, composed of these primary particles, exhibit orientation.
[0367]
[0368] Referring to the figures, it can be determined that in Example 12, the primary particles have specific thicknesses, lengths, aspect ratios, sizes, angles, orientation distances, and so forth. In other words, one can ascertain the particle size (length/width) and aspect ratio, quantitatively analyze the orientation (degree of alignment) of the particles, and confirm the spatial distribution of how the particles are situated with respect to their central axis. In Example 12, the aspect ratio is about 58.7, indicating that the distribution of primary particles is oriented.
[0369] Moreover, the average orientation distance of the primary particles is approximately 0.15 m, which is significantly reduced compared to the comparative example. Thus, in Example 12, the micro primary particles show a clear orientation and form bundles, in stark contrast to the comparative example.
[0370] According to the XRD analysis results illustrated in the figures, I(101)/I(100)-1.87. This indicates that I(101) is higher than I(100)that is, the intensity corresponding to the (101) plane in the XRD pattern is higher than that corresponding to the (100) plane.
[0371] Meanwhile, Table 37 compares the chemical compositions of the positive electrode active materials of Comparative Example 14 and Example 12 of the present invention.
[0372] Table 38 compares their electrochemical performance (capacity, rate capability, cycle life), and Table 39 provides a more detailed comparison of their electrochemical performance, particularly focusing on rate capability.
TABLE-US-00037 TABLE 37 Chemical composition (at %) Cathode Ni Co Mn General co-precipitation 46.2 8.1 45.7 NCM460846 Highly concentrated 46.1 7.9 46.0 Co-precipitation NCM460846
TABLE-US-00038 TABLE 38 0.1 C Disch. 0.2C 0.5C 0.5C Precusor Capa Capacity 0.2C/ Capacity 0.5C/ Cycle Cathode systhesis (mAh/g) Efficiency (mAh/g) 0.1C (mAh/g) 0.1C Cycle Retention General General 215.6 92.7% 205.2 95.2% 190.7 88.5% 100 92.1% NCM460846 co- precipitation Highly Highly 216.2 93.1% 206.1 95.3% 192.3 89.0% 100 96.3% concentrated concentrated Co- Co- precipitation precipitation NCM460846
TABLE-US-00039 TABLE 39 0.2C 0.5C 1C 2C 5C 10C Precusor Capacity Capacity Capacity Capacity Capacity Capacity Cathode systhesis (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g) General General 204.9 191.2 182.1 174.2 152.1 139.2 NCM460846 co- precipitation Highly Highly 206.8 193.1 182.9 177.5 156.9 144.5 concentrated concentrated Co- Co- precipitation precipitation NCM460846
[0373] In Comparative Example 14, a typical co-precipitation reaction was conducted. By contrast, in Example 12, there is a noticeable difference in initial capacity (0.1C) and high-rate charge/discharge capacity (0.2C, 0.5C) compared to Comparative Example 14, and, in particular, Example 12 exhibits a markedly higher capacity retention at 0.5C (100 cycles). This demonstrates that the formation of orientation-type particles in the composite metal hydroxide precursor of Example 12 via a Highly concentrated co-precipitation reaction significantly enhances the crystal structural stability of the precursor, thereby greatly improving its cycle life characteristics.
[0374] Meanwhile,
Comparative Example 15 and Example 13
[0375]
[0376]
[0377] In Example 13, a Highly concentrated co-precipitation reaction is performed on the [Ni.sub.0.51Mn.sub.0.49](OH).sub.2 composite metal hydroxide precursor. As shown in the figures, Example 13 also exhibits a composite metal hydroxide precursor composed of bundles of micro primary particles, each having a thickness of about 1-50 nm.
[0378] Furthermore, orientation-type particles are observed not only in the primary particles each of which is formed by bundles of micro primary particlesbut also within the secondary particles, which comprise multiple primary particles. In other words, each primary particle is made up of bundles of micro primary particles, the major axis of the micro primary particles aligns with that of the primary particle, and the secondary particles, composed of these primary particles, demonstrate orientation.
[0379]
[0380] From these figures, one can confirm the thickness, length, aspect ratio, size, angle, orientation distance, etc., of the primary particles in Example 13. Specifically, the particle size (length/width) and aspect ratio can be assessed, the orientation (degree of alignment) of the particles can be analyzed quantitatively, and the spatial distribution of how the particles are arranged with respect to their central axis can be determined. In Example 13, the aspect ratio is about 49.2, indicating that the distribution of primary particles is oriented.
[0381] Moreover, the average orientation distance of the primary particles is about 0.14 m, which is significantly reduced compared to the comparative example. Thus, in Example 13, the micro primary particles clearly exhibit orientation and form bundles, in contrast to the comparative example.
[0382]
[0383] Meanwhile, Table 40 compares the chemical compositions of the positive electrode active materials of Comparative Example 15 and Example 13 of the present invention. Table 41 compares their electrochemical performance (capacity, rate capability, and cycle life). Table 42 provides a more detailed comparison of their electrochemical performance, particularly with a focus on rate capability.
TABLE-US-00040 TABLE 40 Chemical composition (at %) Cathode Ni Mn General co-precipitation 51.8 48.2 NM5149 Highly concentrated 51.1 48.9 Co-precipitation NM5149
TABLE-US-00041 TABLE 41 0.1 C Disch. 0.2C 0.5C 0.5C Precusor Capa Capacity 0.2C/ Capacity 0.5C/ Cycle Cathode systhesis (mAh/g) Efficiency (mAh/g) 0.1C (mAh/g) 0.1C Cycle Retention General co- General 217.2 93.1% 206.1 94.9% 192.4 88.6% 100 91.5% precipitation co- NM5149 precipitation Highly Highly 217.9 93.1% 207.5 95.2% 194.2 89.1% 100 96.5% concentrated concentrated Co- Co- precipitation precipitation NM5149
TABLE-US-00042 TABLE 42 0.2C 0.5C 1C 2C 5C 10C Precusor Capacity Capacity Capacity Capacity Capacity Capacity Cathode systhesis (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g) (mAh/g) General co- General 205.9 190.2 183.5 176.7 155.6 142.6 precipitation co- NM5149 precipitation Highly Highly 207.4 193.8 183.8 179.4 159.1 147.6 concentrated concentrated Co- Co- precipitation precipitation NM5149
[0384] In Comparative Example 15, a typical co-precipitation reaction was carried out. By contrast, in Example 13, there is a noticeable difference in initial capacity (0.1C) and high-rate charge/discharge capacity (0.2C, 0.5C) compared to Comparative Example 15, and particularly, Example 13 exhibits a markedly higher capacity retention at 0.5C (100 cycles). This result indicates that, in the composite metal hydroxide precursor of Example 13, the formation of orientation-type particles through the co-precipitation process substantially enhances the crystal structural stability of the precursor, thereby significantly improving its cycle life characteristics.
[0385] Meanwhile,
[0386] The following is a description of the manufacturing process according to the present invention.
[Co-Precipitation Reaction Process According to an Embodiment of the Present Invention]
[0387] The co-precipitation reaction process of the present invention refers to a reaction in which two or more metal ions (e.g., transition metal ions) are simultaneously precipitated in a single reaction solution to form a composite compound.
[0388] For example, transition metal ions such as nickel (Ni), cobalt (Co), and manganese (Mn) are mixed in a predetermined ratio, and then an alkaline solution (e.g., NaOH) and a complexing agent (e.g., NH.sub.3) are added together to precipitate hydroxides in the form of ((NixCoyMn1xy)(OH).sub.2).
[0389] Since each metal ion is precipitated simultaneously, the finally formed precipitate (precursor) can be uniformly synthesized, thereby enabling the production of a precursor having a desired composition ratio and structure.
(a) Raw Material Solution Preparation Step
[0390] Nickel sulfate (NiSO.sub.4.Math.6H.sub.2O), cobalt sulfate (CoSO.sub.4.Math.7H.sub.2O), and manganese sulfate (MnSO.sub.4.Math.H.sub.2O) are prepared, and these are mixed in a molar ratio of Ni:Co:Mn=x:y:(1xy) to prepare a metal solution with a concentration of 2.5M. Subsequently, a first dopant is prepared for the co-precipitation process, wherein the first dopant comprises at least one selected from the group consisting of Sb, Mo, W, Nb, Te, Ta, Zr, Ti, Sn, Y, In, Sr, Ba, Mg, Ca, B, V, Cr, Al, and Fe. The average concentration of the first dopant is in the range of 0.01 mol % to 5 mol % relative to the total metal content, including Ni, Co, and Mn.
[0391] The final composition of the mixed metal ions (transition metals) may vary depending on the specific embodiment, and uniform mixing of the metal composition is crucial to impart the desired crystallographic orientation.
(b) Setting of Reaction Solution Concentration and Injection Amount
[0392] An ammonia solution (NH.sub.4OH) and a sodium hydroxide solution (NaOH) required for the co-precipitation reaction are pre-prepared at specific concentrations (e.g., 20M and 6M, respectively). The concentrations and flow rates of the metal ion solution, the NaOH solution (used as an alkaline pH control agent), and the NH.sub.4OH solution (used as a complexing agent) are pre-determined.
[0393] For improved crystallographic orientation, it is essential that the mixing ratio of the metal ions remains homogeneous, as this facilitates the formation of the desired crystal structure and crystal plane orientation. The concentration and injection ratio of complexing agents such as ammonia play a critical role in controlling the crystallographic growth direction during crystal formation.
(c) Co-Precipitation Reaction Step
[0394] The co-precipitation reaction is carried out by injecting an ammonia solution and a sodium hydroxide solution into a co-precipitation reactor and conducting the co-precipitation reaction for a duration of 30 to 60 hours.
[0395] During the reaction, nitrogen gas is supplied to the co-precipitation reactor at a flow rate of 100 L/min to 200 L/min, while maintaining the temperature of the reactor between 40 C. and 60 C., preferably at 50 C. The reactor is stirred at a speed of 200 to 300 rpm, and the pH within the reactor is maintained in the range of 10 to 12.
[0396] In a specific experimental example, a large-capacity co-precipitation reactor (e.g., a 2000 L-class reactor with a rotation motor output of at least 30 KW) is filled with 500 L of distilled water. Nitrogen gas is supplied at 150 L/min to create an inert nitrogen atmosphere within the reactor, thereby reducing dissolved oxygen to prevent oxidation or undesirable side reactions. The reaction temperature is maintained at 50 C., and the stirring speed is set to 250 rpm.
[0397] The pre-prepared 2.5M metal solution is continuously injected at a controlled flow rate (e.g., 40 L/hr) for 20 hours. Simultaneously, 20M ammonia solution (NH.sub.4OH) is injected at a flow rate of 4.5 L/hr, and 6M sodium hydroxide solution (NaOH) is injected at 25 L/hr for 20 hours. The pH of the reaction solution is maintained within the range of 10 to 12, requiring continuous pH monitoring and feedback control.
[0398] The mechanism of orientation formation within the co-precipitation reactor involves hydroxide precipitation reactions facilitated by metal ions (M.sup.2+), hydroxide ions (OH.sup.), and ammonia (NH.sub.3), leading to the formation of composite metal hydroxide ((NixCoyMn1xy)(OH).sub.2). The synthesized composite metal hydroxide undergoes growth, forming primary particles, fine bundled primary particles, and secondary particles.
[0399] Sufficient stirring and the appropriate control of temperature, pH, and complexing agent concentration promote orientation growth along specific crystal planes. Proper management of stirring conditions and reactant injection parameters ensures the uniform growth of particles, particularly to achieve the desired structural orientation. When complexation reactions with ammonia complexes proceed smoothly, defects within the crystal structure are minimized, leading to even crystal growth along specific crystal planes.
[0400] After the co-precipitation reaction, the concentration of composite metal hydroxide particles in the resulting solution is typically about 0.1 kg of precursor per liter of solution. The composite metal hydroxide is then subjected to post-treatment, including filtration and washing, to obtain the final precursor powder.
[0401] In the first embodiment of the present invention, key factors for improving orientation include temperature, pH, stirring speed, and the ammonia solution injection ratio. Specifically, in the first embodiment, the reaction conditions of temperature: 4060 C. (preferred 50 C.), pH: 10-12, stirring speed: 250 rpm, and ammonia solution injection ratio serve as crucial parameters for directing crystal growth along a specific orientation.
[0402] The co-precipitation reaction is carried out by injecting ammonia and sodium hydroxide solutions into the co-precipitation reactor, maintaining a reaction duration of 30 to 60 hours, supplying nitrogen gas at a flow rate of 100 L/min to 200 L/min, and controlling the reactor temperature within the range of 40 C. to 60 C., preferably at 50 C. The stirring speed is maintained at 200 to 300 rpm, and the pH within the reactor is controlled within the range of 10 to 12.
[0403] In addition to the contents of nickel, cobalt, and manganese, the degree of complexation with ammonia (extent of complex formation) during co-precipitation plays a critical role in orientation formation. Furthermore, ensuring a sufficiently long reaction time (at least 20 hours) is essential for allowing uniform and gradual crystal growth.
(d) Post-Treatment (Filtration, Washing, Drying, etc.) Step
[0404] After the completion of the co-precipitation reaction, the slurry containing the composite metal hydroxide is filtered to separate the solid from the liquid phase. The obtained solid is washed with distilled water to remove any residual reaction byproducts. During the washing process, care must be taken to prevent sudden pH fluctuations or excessive physical agitation, which could disrupt the crystallographic orientation.
[0405] The washed wet filter cake is then dried under appropriate conditions (e.g., at 100-120 C.) to obtain the precursor in powder form. The drying conditions, including temperature, duration, and vacuum level, are optimized to minimize structural deformation and particle agglomeration. The final dried composite metal hydroxide precursor is analyzed using SEM, TEM, and XRD to evaluate particle morphology (primary and secondary particles), average particle size, crystal structure, and orientation.
[0406] In the embodiment of the present invention, excessively high drying temperatures or rapid dehydration can cause surface shrinkage and cracking of the particles, adversely affecting crystal orientation. TEM analysis can be utilized to assess whether the long-axis direction of the fine primary particles is aligned parallel to the long-axis of the secondary particles, which is a key factor in determining orientation.
[0407] Additionally, to achieve a more uniform secondary particle formation, spray drying may be employed after the filtration and washing steps. Alternatively, an aging process may be introduced immediately after co-precipitation to allow sufficient growth of fine particles, thereby facilitating more precise crystal plane alignment.
[0408] In NCM and NCA systems, increasing the Ni content can lead to challenges in particle surface stability and homogeneity. Thus, to maximize orientation, pH, temperature, and complexing agent concentration must be readjusted accordingly. A densely oriented precursor contributes to the high-power and high-energy characteristics of the cathode material, as the alignment of ion and electron diffusion pathways within the crystal structure improves charge/discharge efficiency and cycle life.
[0409] The aforementioned co-precipitation synthesis method is a precursor manufacturing process in which multiple metal ions, such as nickel, cobalt, and manganese, are simultaneously precipitated. In the first embodiment of the present invention, the key to improving orientation is the precise control of co-precipitation reaction conditions (temperature, stirring speed, pH, complexing agent concentration and injection ratio, reaction time, etc.) to ensure uniform crystal growth in a specific direction.
[0410] Furthermore, even in the post-treatment process (washing and drying), it is crucial to maintain the structural stability and orientation of the particles. By systematically managing each step, it is possible to manufacture and control a secondary battery cathode active material precursor with improved orientation more effectively, ultimately contributing to the enhancement of battery performance, including power output, lifespan, and energy density.
[Co-Precipitation Reaction According to an Embodiment of the Present Invention: Highly Concentrated]
[0411] In the co-precipitation reaction step, the process of performing the co-precipitation reaction may include removing the solution remaining inside the co-precipitation reactor to the outside of the reactor. The composite metal hydroxide formed by the co-precipitation reaction may be provided in the form of secondary particles in which multiple primary particles are aggregated. The co-precipitation reaction step may be carried out as a highly concentrated co-precipitation reaction.
[0412] The highly concentrated co-precipitation reaction may be performed by removing the accumulated solution inside the co-precipitation reactor during the reaction process. When removing the solution from the co-precipitation reactor, only the solvent is removed while maintaining the solid-state precursor particles generated during the co-precipitation reaction inside the reactor. As a result, the weight ratio of the precursor to the solution within the reactor continuously increases, thereby inducing precursor particles to grow at a lower rate.
[0413] During the highly concentrated co-precipitation reaction, the growth rate of the precursor particles is lower than that of conventional co-precipitation reactions, allowing the primary particles to form in a columnar structure and grow in a unidirectional alignment. Additionally, even during the aggregation process of the primary particles, the high orientation of the aggregated particles is maintained, improving the alignment and orientation of primary particles within the secondary particles.
[0414] The highly concentrated co-precipitation reaction may be carried out for a duration of 30 to 60 hours. Furthermore, after the completion of the highly concentrated co-precipitation reaction, the composite metal hydroxide precursor inside the reactor may be present at a high concentration of at least 0.2 kg of precursor per liter of solution. Specifically, the precursor concentration may range from 0.2 kg precursor/L solution to 0.9 kg precursor/L solution. By maintaining the solution concentration in the aforementioned range after the completion of the highly concentrated co-precipitation reaction, the morphology of the primary particles forming the composite metal hydroxide can be controlled to grow into a unidirectional columnar shape, and the primary particles can have a high degree of orientation toward the center of the secondary particles.
[0415] In conventional co-precipitation reactions, the concentration of the solution inside the co-precipitation reactor is increased by circulating the transition metal solution and ammonia-containing solution externally. Consequently, concentration differences arise between the internal and external solutions, which interfere with the uniform growth of primary precursor particles and ultimately degrade the orientation of the resulting primary particles. Moreover, during the process of circulating the solution outside the co-precipitation reactor, inconsistencies in the transition metal-ammonia complex ion formation reaction occur, leading to discontinuous and non-uniform co-precipitation reactions, which hinder the growth of oriented particles.
[0416] In contrast, the co-precipitation reaction according to an embodiment of the present invention is performed as highly concentrated co-precipitation reaction, in which the solution inside the co-precipitation reactor is not circulated externally. Instead, only the solvent is continuously and selectively removed in real-time from the internal solution. As a result, the overall concentration of the precursor-forming composite metal hydroxide solution remains uniform within the co-precipitation reactor, allowing the transition metal-ammonia chelation reaction and hydroxide substitution reaction to proceed continuously.
[0417] Therefore, highly concentrated co-precipitation reaction promotes the bundling of fine primary particles and the continuous growth of oriented particles, thereby enhancing the orientation of the primary particles forming the composite metal hydroxide.
[Co-Precipitation Reaction According to an Embodiment of the Present Invention: Hetero-Element Doping Co-Precipitation Synthesis]
[0418] According to another embodiment of the present invention, the co-precipitation reaction step may further include wet co-doping, wet shell doping, and hetero-element coating co-precipitation synthesis.
[0419] In wet doping, a hetero-element other than Ni, Co, and Mn is introduced into the co-precipitation reactor. The hetero-element compound may include at least one or more selected from metal hydroxides, metal oxides, and metal sulfides. For example, ammonium molybdate ((NH.sub.4).sub.6Mo.sub.7O.sub.24) or sodium molybdate (Na.sub.2MoO.sub.4) may be used for Mo wet doping. However, the types of compounds used are not limited thereto. The first dopant or hetero-element may include at least one selected from Sb, Mo, W, Zr, Ti, Sn, Y, Mg, B, Al, and Fe.
[0420] The average concentration of the first dopant is preferably between 0.01 mol % and 5 mol % relative to the total metal content including Ni, Co, and Mn. If the average concentration of the first dopant is below 0.01 mol %, the grain growth control effect may be insufficient, making it difficult to regulate grain size, and hindering the formation of plate-like or directionally grown particles with high orientation. Additionally, a lack of dopant may lead to an increase in particle agglomeration, resulting in low orientation and the formation of bulk-shaped particles.
[0421] On the other hand, if the first dopant exceeds 5 mol %, significant deformation of the original crystal structure may occur, inhibiting the formation of oriented particles. Furthermore, if the size of the doping element differs significantly from that of Ni, Co, and Mn, uneven doping may increase defects, distorting particle growth. Excessive doping may also excessively suppress particle growth, leading to the formation of excessively small primary particles, thereby preventing proper orientation.
[0422] Wet doping can be performed using a synthesis process similar to general co-precipitation synthesis. However, it differs in that the hetero-element compound is added to the co-precipitation reactor and dissolved in the transition metal solution or caustic soda solution. A solution containing the hetero-element compound is continuously introduced into the co-precipitation reactor while adjusting the feeding rate, pH, or ammonia concentration depending on the type of hetero-element.
[0423] Through wet doping, the hetero-element can undergo a chelating reaction with Ni, Co, and Mn. As a result, the precursor, which is a composite metal hydroxide, forms fine primary particles while extending their length, and the primary particles exhibit high orientation toward the center of the secondary particles. Furthermore, when the hetero-element is incorporated into the composite metal hydroxide through wet doping, the oriented particles formed in the precursor can be retained in the positive electrode active material subsequently produced.
(Wet Co-Doping)
[0424] Wet co-doping is a method in which, during precursor synthesis, at least two hetero-elements (e.g., Al, Mg, W) are simultaneously introduced along with the main metal ions (e.g., Ni, Co, Mn) to perform co-precipitation synthesis. That is, by dissolving and introducing the desired hetero-elements into the solution throughout the entire nucleation and growth process of the precursor, the elements are evenly impregnated throughout the particle from the core to the surface.
[0425] Because wet co-doping ensures uniform distribution of hetero-elements from the core to the surface, it enhances structural stability, suppresses internal cracking, and provides overall structural reinforcement.
(Wet Shell-Doping)
[0426] Wet shell-doping is a method in which hetero-elements are precipitated only during the final stage (or latter part) of precursor synthesis, preventing doping in the particle's interior while incorporating the hetero-elements only in a region within 2 m from the surface (shell). As a result, a dual structure is formed in which the metal composition of the core and shell differ.
[0427] Since surface degradation mainly occurs during charge and discharge cycles, wet shell-doping selectively introduces dopant elements (e.g., Al, Mg, Ti) into the surface region, effectively improving structural stability and suppressing degradation.
(Hetero-Element Coating Co-Precipitation Synthesis)
[0428] Hetero-element coating co-precipitation synthesis is a method in which, immediately after precursor formation or after the precursor is fully synthesized, a hetero-element layer (or a composite hydroxide/oxide coating layer) is precipitated only on the surface. Structurally, this appears similar to wet shell-doping, but because the hetero-element is coated on the precursor surface after synthesis is complete, it forms a separate coating layer rather than being incorporated into the precursor lattice via substitution (doping).
[0429] This process is performed by maintaining the synthesized precursor particles in a slurry state in a separate or the same reactor, introducing a hetero-element solution (e.g., Al(NO.sub.3).sub.3, MgSO.sub.4, ZrO(NO.sub.3).sub.2), and appropriately adjusting the base (e.g., NaOH), pH, temperature, and stirring conditions to induce the formation of a thin film coating on the precursor surface as a hydroxide (OH), oxide (O), or composite compound.
[0430] Because hetero-element coating co-precipitation forms a doping/coating layer only on the surface while maintaining the internal composition of the precursor, it suppresses side reactions at the surface, improves electrolyte stability, and enhances lifespan characteristics by protecting the surface even under high temperature and high voltage conditions.
[Co-precipitation Reaction According to an Embodiment of the Present Invention: Use of Seed Precursor]
[0431] According to another embodiment of the present invention, the method for manufacturing a cathode active material for a secondary battery may further include the use of a seed precursor in the co-precipitation reaction step. The co-precipitation reaction step may be performed sequentially in two stages: a primary co-precipitation reaction and a secondary co-precipitation reaction. In the primary co-precipitation reaction, the seed precursor is first synthesized, and the secondary co-precipitation reaction is subsequently carried out using the seed precursor to produce a composite metal hydroxide.
[0432] The seed precursor is synthesized with an average particle diameter of 1.5 to 3.5 m, following the same synthesis method as that of the composite metal hydroxide but with a shorter reaction time of approximately 5 to 10 hours.
[0433] In the secondary co-precipitation reaction, the seed precursor is introduced into a co-precipitation reactor containing distilled water, followed by an initial stirring step for a predetermined period. After stirring, a transition metal solution, an ammonia solution, and a sodium hydroxide solution are continuously added into the co-precipitation reactor to proceed with the reaction.
[0434] During the secondary co-precipitation reaction, primary particles are aligned and formed on the surface of the seed precursor. The seed precursor plays a critical role in inducing the alignment and improved orientation of the primary particles, leading to the formation of a highly oriented composite metal hydroxide.
[Co-Precipitation Reaction According to an Embodiment of the Present Invention: Use of Hetero-Element Compound Seed]
[0435] This process involves a co-precipitation reaction for synthesizing a composite metal hydroxide precursor by utilizing ultrafine hetero-element compound seed particles. Specifically, hetero-element compound seeds with a particle size of 1 m or less are introduced at the early stage of the reaction, allowing the formation and growth of new composite metal hydroxide crystals on their surface.
[0436] For example, hetero-element compounds such as Sb.sub.2O.sub.3, WO.sub.3, and Nb.sub.2O.sub.5 (including metal oxides and metal sulfides) are subjected to ultrasonic treatment to refine their D50 particle size to 1 m or less. The ultrasonic treatment ensures that the seed particles remain small and uniformly distributed, thereby increasing their surface area, which facilitates nucleation and uniform crystal growth during the subsequent co-precipitation reaction.
[0437] After ultrasonic treatment, the fine seed particles are introduced into a reactor containing distilled water and stirred thoroughly. Adequate stirring time is ensured to achieve uniform dispersion of the seed particles, allowing them to function effectively as nucleation sites during the co-precipitation process.
[0438] Following a predetermined stirring period, a transition metal solution (containing metal ions such as Ni, Co, and Mn), an ammonia solution, and a sodium hydroxide (NaOH) solution are continuously added to the reactor. This process induces the precipitation of composite metal hydroxide precursor particles on the surface of the hetero-element compound seed particles. By precisely controlling reaction conditions such as pH, temperature, and flow rate, the composite metal hydroxide precursor is deposited uniformly on the seed surface.
[0439] Through this process, new composite metal hydroxide crystals grow on the surface of the seed particles, leading to the gradual formation of fine primary particles. These primary particles aggregate densely while maintaining an internally aligned crystal orientation, forming oriented primary particles.
[0440] A precursor with enhanced orientation contributes to improved electrochemical performance (e.g., higher energy density, longer cycle life, and improved safety) when subjected to calcination and lithium incorporation in the subsequent cathode active material synthesis process.
[0441] Various hetero-element compound seeds that can be used in the co-precipitation reaction process include, but are not limited to, the following: Sb(CH.sub.3CO.sub.2).sub.3, Sb.sub.2O.sub.3, Sb.sub.2O.sub.3, MoO.sub.3, (NH.sub.4).sub.10Mo.sub.7O.sub.24, WO.sub.3, H.sub.2WO.sub.4, (NH.sub.4).sub.10H.sub.2W.sub.12O.sub.42, Nb.sub.2O.sub.5, C.sub.4H.sub.4NNbO.sub.9, TeO.sub.2, Ta.sub.2O.sub.2, ZrO.sub.2, Zr(SO.sub.4).sub.2, TiO.sub.2, Ti(SO.sub.4).sub.2, SnO.sub.2, sSnO.sub.5, TiO.sub.2, SnO.sub.2, Y.sub.2O.sub.3, In.sub.2O.sub.3, SrO, BaO, V.sub.2O.sub.5, Cr.sub.2O.sub.3, Al.sub.2O.sub.3, Al(OH).sub.3, Al.sub.2(SO.sub.4).sub.3.
[Co-Precipitation Reaction According to an Embodiment of the Present Invention: Concentration-Gradient Composite Metal Hydroxide Precursor]
[0442] Another embodiment of the present invention provides a method for manufacturing a concentration-gradient (CG) composite metal hydroxide precursor.
[0443] In this embodiment, a method for producing a concentration-gradient precursor is provided, wherein the composition of the core and surface regions differs. During the co-precipitation synthesis step, the composition of the metal ion solution is gradually varied to form a Ni-rich composition in the core region (e.g., Ni:Co:Mn=100:0:0), while the surface region contains Co and Mn (e.g., Ni:Co:Mn=80:10:10).
[0444] According to an embodiment of the present invention, various compositions such as NCM, NM, NC, and NCMA may be used to control the transition metal composition within the precursor. The synthesized precursor alleviates internal stress during charge and discharge, thereby improving long-term cycle life compared to conventional materials.
[0445] A more detailed explanation of the method for manufacturing a concentration-gradient composite metal hydroxide precursor is provided below. In this embodiment, at least one or more of Ni, Co, Mn, Al, and dopants are distributed in a concentration gradient in at least a portion of the composite metal hydroxide precursor.
Manufacturing Example 1 (Gradient NM90)
[0446] A co-precipitation reactor (capacity: 40 L, rotation motor output: at least 750 W) was filled with 10 liters of distilled water, and nitrogen (N.sub.2) gas was supplied at a rate of 6 L/min. The temperature of the reactor was maintained at 45 C., and stirring was performed at 350 rpm.
[0447] Nickel sulfate solution (NiSO.sub.4.Math.6H.sub.2O, Samchun Chemical) and manganese sulfate solution (MnSO.sub.4.Math.H.sub.2O, Samchun Chemical) were mixed in a molar ratio of Ni:Mn=100:0 to prepare a 2M second metal solution.
[0448] The prepared first metal solution was continuously introduced into the reactor at a rate of 0.561 L/h, along with a 16M ammonia solution (NH.sub.4OH, JUNSEI) at 0.08 L/h and a 4M sodium hydroxide solution (NaOH, Samchun Chemical) at 0.60 L/h, for 14 hours to form the first concentration maintenance region.
[0449] Subsequently, the second metal solution was introduced into the first metal solution reservoir at a rate of 0.561 L/h, gradually changing the concentration of the metal solution introduced into the reactor over 10 hours, thereby forming the second concentration-gradient region around the first concentration maintenance region.
[0450] Afterward, the introduction of the second metal solution into the first metal solution was stopped, and only the first metal solution with a modified concentration was introduced into the reactor at a rate of 0.561 L/h to form the third concentration maintenance region outside the second concentration-gradient region.
[0451] Co-precipitation was performed while maintaining the reactor pH in the range of 10 to 12, producing a concentration-gradient composite metal hydroxide with an average composition of Ni.sub.0.90Mn.sub.0.10(OH).sub.2.
[0452] The produced concentration-gradient Ni.sub.0.90Mn.sub.0.10(OH).sub.2 composite metal hydroxide was filtered, washed multiple times with distilled water, and vacuum dried at 110 C. for 12 hours to obtain a powder.
[0453] The powder was then mixed with lithium hydroxide (LiOH) according to the molar ratio listed in Table 3 and subjected to a pre-sintering process by heating at a rate of 2 C./min, maintaining it at 450 C. for 5 hours.
[0454] Finally, the material was sintered at 730 C. for 10 hours to produce a concentration-gradient NM-type positive electrode active material powder.
Manufacturing Example 2 (Gradient NCM90)
[0455] A co-precipitation reactor (capacity: 40 L, rotation motor output: at least 750 W) was filled with 10 liters of distilled water, and nitrogen (N.sub.2) gas was supplied at a rate of 6 L/min. The temperature of the reactor was maintained at 45 C., and stirring was performed at 350 rpm.
[0456] Nickel sulfate solution (NiSO.sub.4:6H.sub.2O, Samchun Chemical), cobalt sulfate solution (CoSO.sub.4:7H.sub.2O, Samchun Chemical), and manganese sulfate solution (MnSO.sub.4.Math.H.sub.2O, Samchun Chemical) were mixed in a molar ratio of Ni:Co:Mn=100:0:0 to prepare a 2M first metal solution and in a molar ratio of Ni:Co:Mn=80:10:10 to prepare a 2M second metal solution.
[0457] The prepared first metal solution was continuously introduced into the reactor at a rate of 0.561 L/h, along with a 16M ammonia solution (NH.sub.4OH, JUNSEI) at 0.08 L/h and a 4M sodium hydroxide solution (NaOH, Samchun Chemical) at 0.60 L/h, for 14 hours to form the first concentration maintenance region.
[0458] Subsequently, the second metal solution was introduced into the first metal solution reservoir at a rate of 0.561 L/h, gradually changing the concentration of the metal solution introduced into the reactor over 10 hours, thereby forming the second concentration-gradient region around the first concentration maintenance region.
[0459] Afterward, the introduction of the second metal solution into the first metal solution was stopped, and only the first metal solution with a modified concentration was introduced into the reactor at a rate of 0.561 L/h to form the third concentration maintenance region outside the second concentration-gradient region.
[0460] Co-precipitation was performed while maintaining the reactor pH in the range of 10 to 12, producing a concentration-gradient composite metal hydroxide with an average composition of Ni.sub.0.90Co.sub.0.05Mn.sub.0.05(OH).sub.2.
[0461] The produced concentration-gradient Ni.sub.0.90Co.sub.0.05Mn.sub.0.05(OH).sub.2 composite metal hydroxide was filtered, washed multiple times with distilled water, and vacuum dried at 110 C. for 12 hours to obtain a powder.
[0462] The powder was then mixed with lithium hydroxide (LiOH) according to the molar ratio listed in Table 3 and subjected to a pre-sintering process by heating at a rate of 2 C./min, maintaining it at 450 C. for 5 hours.
[0463] Finally, the material was sintered at 730 C. for 10 hours to produce a concentration-gradient NCM-type positive electrode active material powder.
Manufacturing Example 3 (Gradient NC96)
[0464] A co-precipitation reactor (capacity: 40 L, rotation motor output: at least 750 W) was filled with 10 liters of distilled water, and nitrogen (N.sub.2) gas was supplied at a rate of 6 L/min. The temperature of the reactor was maintained at 45 C., and stirring was performed at 350 rpm.
[0465] Nickel sulfate solution (NiSO.sub.4:6H.sub.2O, Samchun Chemical) and cobalt sulfate solution (CoSO.sub.4.Math.7H.sub.2O, Samchun Chemical) were mixed in a molar ratio of Ni:Co=100:0 to prepare a 2M second metal solution.
[0466] The prepared first metal solution was continuously introduced into the reactor at a rate of 0.561 L/h, along with a 16M ammonia solution (NH.sub.4OH, JUNSEI) at 0.08 L/h and a 4M sodium hydroxide solution (NaOH, Samchun Chemical) at 0.60 L/h, for 14 hours to form the first concentration maintenance region.
[0467] Subsequently, the second metal solution was introduced into the first metal solution reservoir at a rate of 0.561 L/h, gradually changing the concentration of the metal solution introduced into the reactor over 10 hours, thereby forming the second concentration-gradient region around the first concentration maintenance region.
[0468] Afterward, the introduction of the second metal solution into the first metal solution was stopped, and only the first metal solution with a modified concentration was introduced into the reactor at a rate of 0.561 L/h to form the third concentration maintenance region outside the second concentration-gradient region.
[0469] Co-precipitation was performed while maintaining the reactor pH in the range of 10 to 12, producing a concentration-gradient composite metal hydroxide with an average composition of Ni.sub.0.96Co.sub.0.04(OH).sub.2.
[0470] The produced concentration-gradient Ni.sub.0.96Co.sub.0.04(OH).sub.2 composite metal hydroxide was filtered, washed multiple times with distilled water, and vacuum dried at 110 C. for 12 hours to obtain a powder.
[0471] The powder was then mixed with lithium hydroxide (LiOH) according to the molar ratio listed in Table 3 and subjected to a pre-sintering process by heating at a rate of 2 C./min, maintaining it at 450 C. for 5 hours.
[0472] Finally, the material was sintered at 730 C. for 10 hours to produce a concentration-gradient NC-type (gradient NC) positive electrode active material powder.
[Manufacturing of Positive Electrode Active Material According to an Embodiment of the Present Invention]
[0473] The positive electrode active material according to this embodiment is produced by calcining a composite metal hydroxide containing at least one or more selected from nickel (Ni), cobalt (Co), manganese (Mn), and aluminum (Al) with a lithium compound. The positive electrode active material may include at least one selected from NC-type, NCM-type, NCA-type, LNO-type, and NCMA-type materials.
[0474] For example, NC-type, NCM-type, NCA-type, and NCMA-type materials are classified based on the types of metal elements in the active material, excluding lithium and dopant-added hetero-elements. Specifically, NC-type refers to a positive electrode active material composed of nickel and cobalt, excluding lithium and dopant-added hetero-elements. NCM-type refers to a positive electrode active material composed of nickel, cobalt, and manganese. NCA-type refers to a positive electrode active material composed of nickel, cobalt, and aluminum. NCMA-type refers to a positive electrode active material composed of nickel, cobalt, manganese, and aluminum. Additionally, the positive electrode active material according to this embodiment may further include an LNO-type material, which refers to a positive electrode active material composed of lithium (Li) and nickel (Ni).
[0475] A person skilled in the art to which the present invention pertains will understand that the invention can be embodied in various specific forms without departing from the technical spirit or essential characteristics thereof. Therefore, the embodiments described above should be understood as being illustrative rather than restrictive in all respects.
[0476] The scope of the present invention is defined not by the detailed description provided above but by the claims set forth below. Any modifications or variations that fall within the meaning, scope, and equivalent concepts of the claims should be construed as being included within the scope of the present invention.
[0477] Although certain embodiments and implementations have been described herein, other embodiments and modifications will be apparent from this description. Accordingly, the inventive concepts are not limited to such embodiments, but rather to the broader scope of the appended claims and various obvious modifications and equivalent arrangements as would be apparent to a person of ordinary skill in the art.