MIXED IONIC ELECTRICAL CONDUCTORS FORMED OF NIOBIUM-BASED MATERIALS FOR BATTERIES AND METHODS OF MAKING SAME
20250304463 ยท 2025-10-02
Assignee
Inventors
Cpc classification
C01G41/006
CHEMISTRY; METALLURGY
C01P2004/82
CHEMISTRY; METALLURGY
H01M4/505
ELECTRICITY
H01M4/525
ELECTRICITY
H01M10/0525
ELECTRICITY
C01P2004/62
CHEMISTRY; METALLURGY
International classification
Abstract
A mixed ionic and electronic conductors (MIEC) material for a battery includes a combination of niobium (Nb), tungsten (W), titanium (Ti), and/or oxygen (O) forming a super-MIEC material with an increased alkali ion metal diffusivity. In one example, the MIEC material is a NbWTi-0 material with an anion-to-cation ratio ranging from about 2.33 to about 2.8 where the anion is O and the cation is Nb, W, and Ti. The MIEC material may be a coarse-grained material that includes particles consisting essentially of Nb, W, Ti, and/or O and having a dimension of at least 0.1 m. The MIEC material may have an open pore structure with pores having a pore diameter from about 2.5 to about 2.8 . The MIEC material may also include carbon (C) that coats each particle. The MIEC material may be incorporated into an anode or a cathode of a lithium-ion battery.
Claims
1. A mixed ionic and electrical conductor (MIEC) material for a battery, the MIEC material comprising: niobium (Nb) in an amount having a mass percentage from about 0.1% to about 93% relative to the total mass of the MIEC material; tungsten (W) in an amount having a mass percentage from about 0.1% to about 73% relative to the total mass of the MIEC material; titanium (Ti) in an amount having a mass percentage from about 0.1% to about 26% relative to the total mass of the MIEC material; and oxygen (O) in an amount having a mass percentage of about 22% to about 29% relative to the total mass of the MIEC material.
2. The MIEC material of claim 1, wherein the MIEC material has an alkali metal ion diffusivity of at least 10.sup.16 m.sup.2 s.sup.1.
3. The MIEC material of claim 2, wherein: the alkali metal ion diffusivity is a lithium ion diffusivity; and the MIEC material further comprises: lithium (Li) in an amount having a mass percentage from about 4% to about 12% relative to the total mass of the MIEC material.
4. The MIEC material of claim 1, wherein the MIEC material comprises a plurality of particles consisting essentially of the Nb, the W, the Ti, and the O, each particle of the plurality of particles having a single-crystal structure and at least one dimension that is at least 0.1 m.
5. The MIEC material of claim 1, further comprising: at least one of boron (B), nitrogen (N), phosphorous (P), or sulfur (S).
6. The MIEC material of claim 1, further comprising: carbon (C) in an amount having a mass percentage from about 0.1% to about 20% relative to the total mass of the MIEC material, wherein: the MIEC material comprises a plurality of particles consisting essentially of the Nb, the W, the Ti, and the O; and the C coats the plurality of particles.
7. The MIEC material of claim 1, wherein the MIEC material has a plurality of pores, each pore of the plurality of pores having a pore diameter ranging from about 2.5 to about 2.8 .
8. The MIEC material of claim 1, wherein: the MIEC material has a chemical formula of Nb.sub.xW.sub.yTi.sub.zO.sub.5x/2+3y+2z; x is 20-100; y is 0.1-80; and z is 0.1-70.
9. The MIEC material of claim 8, wherein the MIEC material has an anion-to-cation ratio (ACR) of (5x/2+3y+2z)/(x+y+z), the ACR ranging from about 2.33 to about 2.80.
10. An anode comprising: the MIEC material of claim 1, wherein the MIEC material is present in the anode in an amount having a mass percentage of at least 85% relative to the total mass of the anode.
11. A battery comprising: the anode of claim 10; and a cathode comprising at least one of: LiCoO.sub.2; LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2; LiNi.sub.0.5Co.sub.0.2Mn.sub.0.3O.sub.2; LiNi.sub.0.33Co.sub.0.33Mn.sub.0.33O.sub.2; LiNi.sub.0.5M.sub.1.5O.sub.4; or LiFePO.sub.4.
12. A mixed ionic and electronic conductor (MIEC) material for a battery, the MIEC material comprising: a first amount of oxygen (O); and a second amount of metal, the metal comprising niobium (Nb) and at least one of tungsten (W) or titanium (Ti), wherein: a ratio of the first amount to the second amount ranges from about 2.33 to about 2.8; and the MIEC material comprises a plurality of particles consisting essentially of the oxygen and the metal, each particle of the plurality of particles having a single-crystal structure and at least one dimension that is at least 0.1 m.
13. The MIEC material of claim 12, wherein: the metal comprises W and Ti; and the Nb is present in the MIEC material in an amount having a mass percentage from about 0% to about 93% relative to the total mass of the MIEC material; the W is present in the MIEC material in an amount having a mass percentage from about 0% to about 73% relative to the total mass of the MIEC material; the Ti is present in the MIEC material in an amount having a mass percentage from about 0% to about 26% relative to the total mass of the MIEC material; and the O is present in the MIEC material in an amount having a mass percentage of about 22% to about 29% relative to the total mass of the MIEC material.
14. The MIEC material of claim 12, wherein the MIEC material has a plurality of pores, each pore of the plurality of pores having a pore diameter ranging from about 2.5 to about 2.8 .
15. The MIEC material of claim 12, further comprising: carbon (C) in an amount having a mass percentage from about 0.1% to about 20% relative to the total mass of the MIEC material, the C coating the plurality of particles.
16. A method of making a mixed ionic and electrical conductor (MIEC) material, the method comprising: mixing a niobium (Nb) source, a titanium (Ti) source, and a tungsten (W) source to form a mixture; and heating the mixture to a temperature from about 1000 C. to about 1300 C. for a period from about 0.5 hours to about 60 hours to form the MIEC material, wherein: the Nb source is at least one of Nb.sub.2O.sub.5, NbO.sub.2, NbC, or niobium ethoxide; the Ti source is at least one of anatase TiO.sub.2, rutile TiO.sub.2, or TiO.sub.2B; and the W source is at least one of WO.sub.3 or WO.sub.2.
17. The method of claim 16, wherein: Nb is present in the mixture in an amount having a mass percentage from about 0.1% to about 93% relative to the total mass of the mixture; W is present in the mixture in an amount having a mass percentage from about 0.1% to about 73% relative to the total mass of the mixture; and Ti is present in the mixture in an amount having a mass percentage from about 0.1% to about 26% relative to the total mass of the mixture.
18. The method of claim 16, wherein the step of heating the mixture forms a plurality of particles consisting essentially of Nb, W, Ti, and oxygen (O) in the MIEC material, each particle of the plurality of particles having a single-crystal structure and at least one dimension that is at least 0.1 m.
19. The method of claim 16, wherein the step of mixing further comprises: mixing at least one of a boron (B) source, a nitrogen (N) source, a phosphorous (P) source, or a sulfur (S) source into the mixture.
20. The method of claim 16, wherein: the step of mixing further comprises: mixing one or more carbon precursors into the mixture; the method further comprises: heating the MIEC material to a temperature from about 200 C. to about 1400 C. for a period from about 0.5 hours to about 12 hours in a control atmosphere consisting essentially of argon (Ar) or nitrogen (N.sub.2) to form a carbon coating on the MIEC material; and the one or more carbon precursors comprises one or more of graphite, conductive carbon black, carbon nanotubes, carbon nanospheres, carbon nanofibers, carbon gels, sucrose, glucose, fructose, citric acid, ascorbic acid, starch, cellulose, polypropylene, epoxy resin, polyvinylidene fluoride, polytetrafluoroethylene, polystyrene cyanide, phenolic resin, styrene butadiene rubber emulsion, polystyrene, or carboxymethyl cellulose.
Description
BRIEF DESCRIPTIONS OF THE DRAWINGS
[0025] The skilled artisan will understand that the drawings primarily are for illustrative purposes and are not intended to limit the scope of the inventive subject matter described herein. The drawings are not necessarily to scale; in some instances, various aspects of the inventive subject matter disclosed herein may be shown exaggerated or enlarged in the drawings to facilitate an understanding of different features. In the drawings, like reference characters generally refer to like features (e.g., functionally and/or structurally similar elements).
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DETAILED DESCRIPTION
[0053] Following below are more detailed descriptions of various concepts related to, and implementations of, a MIEC material for a battery that includes niobium (Nb), tungsten (W), titanium (Ti), and/or oxygen (O), such as a NbWTiO material, an electrode and/or a battery that includes the MIEC material, methods for making the MIEC material, and methods for using the MIEC material in a battery. It should be appreciated that various concepts introduced above and discussed in greater detail below may be implemented in multiple ways. Examples of specific implementations and applications are provided primarily for illustrative purposes so as to enable those skilled in the art to practice the implementations and alternatives apparent to those skilled in the art.
[0054] The figures and example implementations described below are not meant to limit the scope of the present implementations to a single embodiment. Other implementations are possible by way of interchange of some or all of the described or illustrated elements. Moreover, where certain elements of the disclosed example implementations may be partially or fully implemented using known components, in some instances only those portions of such known components that are necessary for an understanding of the present implementations are described, and detailed descriptions of other portions of such known components are omitted so as not to obscure the present implementations.
[0055] In the discussion below, various examples of inventive MIEC materials are provided, wherein a given example or set of examples showcases one or more particular features of a material composition, a material morphology, and/or a material property. It should be appreciated that one or more features discussed in connection with a given example of a MIEC material may be employed in other examples of MIEC materials according to the present disclosure, such that the various features disclosed herein may be readily combined in a given MIEC material according to the present disclosure (provided that respective features are not mutually inconsistent).
[0056] Certain dimensions and features of the MIEC material are described herein using the terms approximately, about, substantially, and/or similar. As used herein, the terms approximately, about, substantially, and/or similar indicates that each of the described dimensions or features is not a strict boundary or parameter and does not exclude functionally similar variations therefrom. Unless context or the description indicates otherwise, the use of the terms approximately, about, substantially, and/or similar in connection with a numerical parameter indicates that the numerical parameter includes variations that, using mathematical and industrial principles accepted in the art (e.g., rounding, measurement or other systematic errors, manufacturing tolerances, etc.), would not vary the least significant digit.
1. A MIEC MATERIAL FOR A BATTERY
[0057] The MIEC materials disclosed herein may generally be a Nb-based material. For example, the MIEC material may be a NbWTiO material that includes niobium (Nb), tungsten (W), titanium (Ti), and oxygen (O) elements. In another example, the MIEC material may include Nb, W, and O forming a NbWO material. In yet another example, the MIEC material may include Nb, Ti, and O forming a NbTiO material.
[0058] In one non-limiting example, the MIEC material may be a NbWTiO material where Nb has a mass percentage in a range from about 0.1% to about 70%, W has a mass percentage in a range from about 0.1% to about 70%, Ti has a mass percentage in a range from about 0.1% to about 35%, and O has a mass percentage in a range from about 20% to about 40%. In another non-limiting example, the MIEC material may be a NbWTiO material where Nb has a mass percentage in a range from about 0.1% to about 93%, W has a mass percentage in a range from about 0.1% to about 73%, Ti has a mass percentage in a range from about 0.1% to about 26%, and O has a mass percentage in a range from about 22% to about 29%. More generally, the MIEC material may include O, Nb, and one or both of W and Ti where Nb has a mass percentage in a range from about 0% to about 93%, W has a mass percentage in a range from about 0% to about 73%, Ti has a mass percentage in a range from about 0% to about 26%, and O has a mass percentage in a range from about 22% to about 29%.
[0059] The term about, when used to describe the mass percentages of the constituent elements in the MIEC material (e.g., Nb, W, Ti, O, B, N, S, P, C), is intended to cover variations in composition during manufacture. For example, about 73% can correspond to the following ranges: 71.5% to 74.5% (+/2% variation), 72.3% to 73.7% (+/1% variation), 72.42% to 73.58% (+/0.8% variation), 72.56% to 73.44% (+/0.6% variation), 72.71% to 73.29% (+/0.4% variation), 72.85% to 73.15% (+/0.2% variation), including all values and sub-ranges in between.
[0060] In one non-limiting example, the MIEC material may have the chemical formula Nb.sub.xW.sub.yTi.sub.zO.sub.5x/2+3y+2z. In one example, x may be in the range of 20-100, y is in the range of 0.1-80, and z is in the range of 0.1-70. In another example, x may be in the range of 0-100, y is in the range of 0-80, and z is in the range of 0-70, thus covering NbWO, NbTiO, and NbWTiO materials. In some embodiments, the MIEC material may have a chemical formula of Nb.sub.9W.sub.yTi.sub.zO.sub.22.5+3y+2z, where y is 2-4, and z is 4-6.
[0061] An anion-to-cation ratio (ACR) may be defined as the ratio of (5x/2+3y+2z)/(x+y+z) and may be from about 2.33 to about 2.80. Here, the anion is oxygen and the cation is Nb, W, and Ti. More generally, the ACR may be defined as the ratio of the amount of oxygen to the amount of metal in the MIEC material, as discussed below. The term about, when used to describe the ACR of the MIEC material, is intended to cover variations in composition during manufacture. For example, about 2.5 can correspond to the following ranges: 2.45 to 2.55 (+/2% variation), 2.475 to 2.525 (+/1% variation), 2.48 to 2.52 (+/0.8% variation), 2.485 to 2.515 (+/0.6% variation), 2.49 to 2.51 (+/0.4% variation), 2.495 to 2.505 (+/0.2% variation), including all values and sub-ranges in between.
[0062] In another example, the MIEC material may be Nb.sub.53W.sub.12Ti.sub.35O.sub.120, hereafter called NbWTiO-1. As another example, the MIEC material may be Nb.sub.53W.sub.24Ti.sub.24O.sub.126, hereafter call NbWTiO-2. As another example, the MIEC material may be Nb.sub.38W.sub.56Ti.sub.5O.sub.137. As another example, the MIEC material may be Nb.sub.58W.sub.37Ti.sub.4O.sub.132. As another example, the MIEC material may be Nb.sub.73W.sub.6Ti.sub.21O.sub.121.
[0063] In yet another example, the MIEC material may have a Wadsley-Roth structure. For example, the MIEC material may be a block structured oxide of the form, M.sub.xO.sub.y, where M is a metal (e.g., Nb, Ti, W) and O is oxygen. This form can be used to represent a series of chemical formulas with one single integer variable n, including M.sub.3nO.sub.8n3 for Group A, M.sub.3n+1O.sub.8n2 (n odd) for Group B, M.sub.3n+1O.sub.8n2 (n even) for Group C, M.sub.3n+1O.sub.8n+1 for Group D, M.sub.4n+1O.sub.11n for Group E, and M.sub.5n+1O.sub.14n1 for Group F. Taking the limiting cases as n.fwdarw., and known small n compositions (e.g., n=3 for Nb.sub.2TiO.sub.7 in Group A, n=7 for Nb.sub.22O.sub.54 in Group B, n=8 for Nb.sub.24TiO.sub.62 in Group C, n=3 for Nb.sub.9TPO.sub.25 in Group D, n=3 for Nb.sub.12WO.sub.33 in Group E, and n=4 for Nb.sub.16W.sub.5O.sub.55 in Group F), an O/M ratio may range from about 2.33 to about 2.8. In some embodiments, the MIEC material may have an O/M ratio equal to 2.5, which may be achieved by alloying WO.sub.3 and TiO.sub.2 with a 1:1 molar ratio into a NbO.sub.2.5 matrix.
[0064] The values for the O/M ratio may be used to define a material space in a NbO.sub.2.5WO.sub.3TiO.sub.2 ternary phase diagram where materials within the space have a Wadsley-Roth structure and function as a super MIEC, as shown by the shaded area in
[0065] The MIEC material may be a single crystal or polycrystalline material. Specifically, the MIEC may be a coarse-grained material that includes a plurality of particles. The particles may have various shapes including, but not limited to, a sphere, an ellipsoid, a polyhedron, and any combination of the foregoing. As a result, each particle may be characterized by one or more dimensions (e.g., a characteristic width, a diameter of a sphere, a major axis and a minor axis of an ellipsoid). The dimensions of the particle may be micrometer sized (e.g., 1 m to 100 m) or nanometer sized (1 nm to 999 nm). Preferably, the MIEC material has a particle size with at least one dimension greater than 0.1 m. More preferably, the MIEC material has a particle size with at least one dimension greater than 1 m. Even more preferably, the MIEC material has a particle size with at least one dimension of about 10 m or greater. The term about, when used to describe the dimensions of the particles in the MIEC material, is intended to cover variations in particle size during manufacture. For example, about 1 m can correspond to the following ranges: 0.99 m to 1.01 m (+/1% variation), 0.992 m to 1.008 m (+/0.8% variation), 0.994 m to 1.006 m (+/0.6% variation), 0.996 m to 1.004 m (+/0.4% variation), 0.998 m to 1.002 m (+/0.2% variation), including all values and sub-ranges in between.
[0066] The MIEC material may have a high alkali metal ion diffusivity (D.sub.M) of at least 10.sup.16 m.sup.2 s.sup.1. Preferably, the MIEC material has a D.sub.M that is greater than or equal to 10.sup.14 m.sup.2 s.sup.1. More preferably, the MIEC material has a D.sub.M that is 10.sub.13 m.sup.2 s.sup.1 or higher. In some embodiments, the metal ion, M, may be lithium. The MIEC material may have an open pore structure with pore diameters of about 2.5 to about 2.8 . This pore diameter may exclude molecules (including water) while providing the rapid D.sub.Li described above. This D.sub.Li supports high rate charging up to about 30 C. The MIEC material reduces contact and side reactions with the electrolyte and enhances cycle life up to about 10,000 cycles. The large free volume in the MIEC material from the open pore structure may give rise to other structural and physical properties (e.g., surprisingly low coefficient of thermal expansion (CTE) and/or formation of planar defects, which may buffer strain and facilitate transport during electrochemical cycling). The term about, when used to describe the pore diameter of the MIEC material, is intended to cover variations in morphology during manufacture. For example, about 2.5 can correspond to the following dimensional ranges: 2.475 to 2.525 (+/1% variation), 2.48 to 2.52 (+/0.8% variation), 2.485 to 2.515 (+/0.6% variation), 2.49 to 2.51 (+/0.4% variation), 2.495 to 2.505 (+/0.2% variation), including all values and sub-ranges in between.
[0067] The MIEC material may further include at least one of boron (B), nitrogen (N), phosphorous (P), or sulfur (S). For example, the MIEC material may have a composition of A.sub.uNb.sub.vW.sub.wTi.sub.xM.sub.yO.sub.z, a single-crystal structure (e.g., the particles forming the MIEC material are single crystalline), and a lithium diffusivity of at least 10.sup.15 m.sup.2 s.sup.1. Preferably, A is an alkali metal, M is at least one of B, N, P, or S, u is 0-10, v is 5-20, w is 1-10, x is 1-10, y is 0-5, and z is 18-110.
[0068] The particles in the MIEC material may also be coated with, for example, carbon. In some embodiments, the MIEC material may include carbon (C) in an amount having a mass percentage from about 0.1% to about 20% relative to the total mass of the MIEC material. The carbon coating may be formed, in part, using a high-temperature carbonization process, which is described below in further detail.
[0069] The MIEC material may be formed by mixing together metal oxide powders containing the constituent elements of the MIEC material and then applying a high-temperature heat treatment to the mixture to form and grow particles that comprise the desired composition of Nb, W, Ti, and/or O. For example, a MIEC material that includes Nb, W, Ti, and O may be formed by first mixing a Nb source, a Ti source, and a W source to form a mixture. The Nb source may include, but is not limited to, Nb.sub.2O.sub.5, NbO.sub.2, NbC, and/or niobium ethoxide. The Ti source may include, but is not limited to, anatase TiO.sub.2, rutile TiO.sub.2, and/or TiO.sub.2B. The W source may include, but is not limited to, WO.sub.3 and/or WO.sub.2. The mixture of metal oxide powders may then be heated to a temperature from about 1000 C. to about 1300 C. for a period from about 0.5 hours to about 60 hours.
[0070] The term about, when used to describe the temperature of the heat-treatment process to form a MIEC material, is intended to cover variations in operating temperature that may arise during manufacture and/or when using different equipment to perform the heat-treatment process. For example, about 1000 C. can correspond to the following temperature ranges: 990 C. to 1010 C. (+/1% variation), 992 C. to 1008 C. (+/0.8% variation), 994 C. to 1006 C. (+/0.6% variation), 996 C. to 1004 C. (+/0.4% variation), 998 C. to 1002 C. (+/0.2% variation), including all values and sub-ranges in between. The term about, when used to describe the period of time the heat-treatment process (or the high-temperature carbonization process described below) is applied to the mixture, is intended to cover variations in timing that may arise due to, for example, the heat-treatment process being manually timed or variations in any timing equipment that may be used to perform the heat-treatment process. For example, about 1 hour can correspond to the following ranges: 0.99 hours to 1.01 hours (+/1% variation), 0.992 hours to 1.008 hours (+/0.8% variation), 0.994 hours to 1.006 hours (+/0.6% variation), 0.996 hours to 1.004 hours (+/0.4% variation), 0.998 hours to 1.002 hours (+/0.2% variation), including all values and sub-ranges in between.
[0071] The carbon coating may be formed by mixing various metal oxide powders (e.g., the Nb source, the W source, and the Ti source) together with a carbon precursor. After the high-temperature heat treatment to form the MIEC material, the MIEC material may be subjected to a high-temperature carbonization process where the mixture is heated to a temperature from about 200 C. to about 1400 C. for a time period from about 0.5 hours to about 12 hours in a control atmosphere of argon (Ar) or nitrogen (N.sub.2). This process thus forms a carbon coating on the particles forming the MIEC material. The carbon precursors may include various carbon-based materials including, but not limited to, graphite, conductive carbon black, carbon nanotubes, carbon nanospheres, carbon nanofibers, carbon gels, sucrose, glucose, fructose, citric acid, ascorbic acid, starch, cellulose, polypropylene, epoxy resin, polyvinylidene fluoride, polytetrafluoroethylene, polystyrene cyanide, phenolic resin, styrene butadiene rubber emulsion, polystyrene, carboxymethyl cellulose, and any combinations of the foregoing.
[0072] As described above, the MIEC materials disclosed herein may be incorporated into a battery. For example, a lithium-ion battery may include at least one of the above-disclosed MIEC materials.
[0073] The cathode 110 includes a cathode current collector 112 and a cathode material layer 114. The cathode current collector 112 can be used to support the cathode material layer 114 and conduct current. The shape of the cathode current collector 112 can be a sheet shape or network shape. The cathode current collector 112 can be formed from various materials including, but not limited to, aluminum, titanium, and stainless steel. The cathode material layer 114 can be disposed on at least one surface of the cathode current collector 112.
[0074] The anode 120 includes an anode current collector 122 and an anode material layer 124. The anode current collector 122 can be used to support the anode material layer 124 and conduct current. The anode current collector 122 can be formed in various shapes including, but not limited to, a sheet shape and a network shape. The anode current collector 122 can be formed from various materials including, but not limited to, copper, nickel, and stainless steel. The anode material layer 124 can be disposed on at least one surface of the anode current collector 122.
[0075] In one embodiment, the cathode material layer 114 includes at least one of the above-disclosed MIEC materials as a cathode active material. In this embodiment, the anode material layer 124 includes an anode active material (e.g., graphite) having an electrical potential lower than the MIEC material used as a cathode active material.
[0076] In another embodiment, the anode material layer 124 includes at least one of the above-disclosed MIEC materials as an anode active material. In this embodiment, the cathode material layer 114 includes a cathode active material. The cathode active material 114 may be a lithium transition metal oxide (e.g., lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium iron phosphate, and/or lithium manganese phosphate), having an electrical potential higher than that of the MIEC material. In some embodiments, the lithium transition metal oxide may include at least one of LiCoO.sub.2, LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2, LiNi.sub.0.5Co.sub.0.2Mn.sub.0.3O.sub.2, LiNi.sub.0.33Co.sub.0.33Mn.sub.0.33O.sub.2, LiNi.sub.0.5M.sub.1.5O.sub.4, or LiFePO.sub.4.
[0077] The anode material layer 124 and cathode material layer 114 can further include a conducting agent and/or a binder. In the cathode material layer 114, the cathode active material, the conducting agent, and the binder can be uniformly mixed. In the anode material layer 124, the anode active material, the conducting agent, and the binder can be uniformly mixed. The conducting agent can be one or more carbonaceous materials including, but not limited to, carbon black, conducting polymers, acetylene black, carbon fibers, carbon nanotubes, and graphite. The binder can be at least one of polyvinylidene fluoride (PVDF), polyvinylidene difluoride, polytetrafluoroethylene (PTFE), fluoro rubber, ethylene propylene diene monomer, and styrene-butadiene rubber (SBR). In another embodiment, the cathode material layer 114 can be lithium metal.
[0078] In another example embodiment, the anode material layer 124 may only include one of the above-disclosed MIEC materials as an anode active material. The anode material layer 124 may have no conducting agent because MIEC materials may have intrinsically high electrical conductivities.
[0079] In another embodiment, the cathode material layer 114 may only include one of the above-disclosed MIEC materials as a cathode active material. The cathode material layer 114 may have no conducting agent because MIEC materials have intrinsically high electrical conductivities.
[0080] More generally, the anode material layer 124 or the cathode material layer 114 may contain the MIEC material in a mass percentage of at least 85% of the total mass of the anode material layer 124 or the cathode material layer 114. The MIEC material may have a mass loading of about 1.0 mg per cm.sup.2 to about 20.0 mg per cm.sup.2 in the anode material layer 124 or the cathode material layer 114. The term about, when used to describe the mass loading of the MIEC material in an anode or a cathode, is intended to cover variations in composition during manufacture. For example, about 1.0 mg per cm.sup.2 can correspond to the following ranges: 0.98 mg per cm.sup.2 to 1.02 mg per cm.sup.2 (+/2% variation), 0.99 mg per cm.sup.2 to 1.01 mg per cm.sup.2 (+/1% variation), 0.992 mg per cm.sup.2 to 1.008 mg per cm.sup.2 (+/0.8% variation), 0.994 mg per cm.sup.2 to 1.006 mg per cm.sup.2 (+/0.6% variation), 0.996 mg per cm.sup.2 to 1.004 mg per cm.sup.2 (+/0.4% variation), 0.998 mg per cm.sup.2 to 1.002 mg per cm.sup.2 (+/0.2% variation), including all values and sub-ranges in between.
[0081] The separator 130 may be formed from various materials including, but not limited to, a polyolefin microporous membrane, modified polypropylene fabric, polyethylene fabric, glass fiber fabric, superfine glass fiber paper, vinylon fabric, and composite membrane of nylon fabric and wettable polyolefin microporous membrane composited by welding or bonding. The polyolefin porous membrane may be selected from a polypropylene porous membrane, a polyethylene porous membrane, or a lamination of a polypropylene porous membrane and a polyethylene porous membrane.
[0082] The electrolyte 140 may include a lithium salt and a non-aqueous solvent dissolving the lithium salt. The lithium salt may be at least one of LiPF.sub.6, LiBF.sub.4, LiAsF.sub.6, LiSbF.sub.6, LiClO.sub.4, LiAlCl.sub.4, LiGaCl.sub.4, LiNO.sub.3, LiC(SO.sub.2CF.sub.3).sub.3, LiN(SO.sub.2CF.sub.3).sub.2, LiSCN, LiO.sub.3SCF.sub.2CF.sub.3, LiC.sub.6F.sub.5SO.sub.3, LiO.sub.2CCF.sub.3, LiSO.sub.3F, Li(C.sub.6H.sub.5).sub.4, and LiCF.sub.3SO.sub.3. The non-aqueous solvent may be at least one of ethylene carbonate, propylene carbonate, butylene carbonate, gamma-butyrolactone, dipropyl carbonate, N-methyl pyrrolidone, N-methylformamide, N-methylacetamide, N,N-dimethylformamide, N,N-diethylformamide, acetonitrile, succinonitrile, 1,4-dicyanobutane, glutaronitrile, dimethyl sulfoxide, dimethyl sulfite, vinylene carbonate, ethylmethyl carbonate, dimethyl carbonate, diethyl carbonate, 4-fluoro-1,3-dioxolan-2-one, chloropropylene carbonate, anhydride, sulfolane, methoxymethylsulfone, tetrahydrofuran, 2-methyltetrahydrofuran, epoxy propane, methyl acetate, ethyl acetate, methyl butyrate, ethyl propionate, methyl propionate, 1,3-dioxolane, acetal, 1,2-dimethoxyethane, and 1,2-dibutyldi.
2. EXAMPLE DEMONSTRATIONS OF MIEC MATERIALS
[0083] This section provides several example MIEC materials that were synthesized and characterized. Nb-based materials were fabricated using solid-state synthesis.
[0084]
[0085] As another example, Nb.sub.2O.sub.5, rutile TiO.sub.2, and WO.sub.3 were mixed with a molar ratio of Nb:W:Ti=38:56:5, followed by high-temperature heat treatment at 1300 C. for 60 hours. The heating rate of 2 C. min.sup.1 and furnace cooling were used in the heat treatment processes. The synthesized material was denoted NbWTiO-3 (Nb.sub.38W.sub.56Ti.sub.5O.sub.137).
[0086] As another example, NbC, rutile TiO.sub.2, and WO.sub.2 were mixed with a molar ratio of Nb:W:Ti=58:37:4, followed by high-temperature treatment at 1150 C. for 40 hours. The heating rate of 2 C. min.sup.1 and furnace cooling were used in the heat treatment processes. The synthesized material was denoted NbWTiO-4 (Nb.sub.58W.sub.37Ti.sub.4O.sub.132).
[0087] As another example, niobium ethoxide, TiO.sub.2B, and WO.sub.2 were mixed with a molar ratio of Nb:W:Ti=73:6:21, followed by high-temperature heat treatment at 1250 C. for 0.5 h. The heating rate of 2 C. min.sup.1 and furnace cooling were used in heat treatment processes. The synthesized material was denoted NbWTiO-5 (Nb.sub.73W.sub.6Ti.sub.21O.sub.121).
[0088] As another example, NbWTiO-1 were mixed with glucose solution (the mass ratio of glucose is 5%) followed by heat treatment at 600 C. for 0.5 h under Ar atmosphere. The heating rate of 2 C. min.sup.1 and furnace cooling were used in heat treatment processes. The synthesized material was denoted NbWTiO-1@C.
[0089] As another example, NbWTiO-3 were mixed with certain amounts of dopamine hydrochloride (the mass ratio of dopamine hydrochloride is 25%) with the tris-buffer (pH8.5), followed by heat treatment at 600 C. for 6 h under Ar atmosphere. The heating rate of 5 C. min.sup.1 and furnace cooling were used in heat treatment processes. The synthesized material was denoted NbWTiO-3@C.
[0090] Several materials were compared to the example MIEC materials synthesized above, including Nb.sub.9PO.sub.25 (also called NbPO-1), Nb.sub.2TiO.sub.7 (also called NbTiO-1), and Nb.sub.18W.sub.16O.sub.93 (also called NbWO-1).
[0091]
[0092]
[0093]
[0094]
[0095] The coefficient of thermal expansion (CTE) of the synthesized MIEC samples was measured using in situ XRD measurements conducted at 100 K t about 650 K. The linear CTE was obtained from the refined primary-cell volume V.sub.0(T). Compared to the CTE database for 260 compounds centered around 710.sup.6 K.sup.1, the synthesized MIEC samples all had negative or close-to-zero CTEs. For example, NbWTiO-1 had negative CTEs along all three lattice axes, which is rare and termed isotropic negative CTE. Such anomalously low CTEs may support surface-like adsorption and diffusion of Li.sup.+ in these materials.
[0096]
3. EXAMPLE ELECTRODE PREPARATION AND BATTERY ASSEMBLY
[0097] The NbWTiO-1, conducting carbon black (super P), and binder (sodium carboxymethyl cellulose (CMC) and polymerized styrene-butadiene rubber (SBR) in a weight ratio of 1:1) having a mass ratio of 85:9:6 were added into water solvent, and mixed to obtain a slurry. The slurry was applied on an Al foil as the current collector and dried at 100 C. in a vacuum to obtain an NbWTiO-1 electrode.
[0098] A 2032-coin type lithium-ion battery was assembled in a glove box using lithium metal as the anode, the prepared NbWTiO-1 electrode as the cathode, Celgard 2400 polypropylene porous film as the separator, and a solution of lithium hexafluorophosphate (LiPF.sub.6) in ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) in a 1:1:1 volume ratio as an electrolyte. The concentration of the LiPF.sub.6 in the solution was about 1 mol/L. The glove box was filled with argon gas. Water and oxygen gas in the glove box were both lower than 1 ppm.
[0099] A NbWTiO-2 electrode was made using the same method as above, except that the NbWTiO-1 was replaced by the NbWTiO-2. A 2032-coin type lithium-ion battery was assembled by using the same method as described above with respect to NbWTiO-1, except that the NbWTiO-1 electrode was replaced by the NbWTiO-2 electrode.
[0100] For comparison, an NbPO-1 electrode was made using the same method described above, except that the NbWTiO-1 was replaced by the NbPO-1. A 2032-coin type lithium-ion battery was assembled using the same method described above except that the NbWTiO-1 electrode was replaced by the NbPO electrode.
[0101] For comparison, an NbTiO-1 electrode was made using the same method described above, except that the NbWTiO-1 was replaced by the NbTiO-1. A 2032-coin type lithium-ion battery was assembled using the same method as above except that the NbWTiO-1 electrode was replaced by the NbTiO-1 electrode.
[0102] For comparison, an NbWO-1 electrode is made using the same method described above, except that the NbWTiO-1 was replaced by the NbWO-1. A 2032-coin type lithium-ion battery was assembled using the same method as above except that the NbWTiO-1 electrode was replaced by the NbWO-1 electrode.
[0103] For comparison, a commercially-acquired Li.sub.4Ti.sub.5O.sub.12, conducting carbon black (super P), and polyvinylidene fluoride binder (PVDF) having a mass ratio of 85:7.5:7.5 were added into N-methyl-2-pyrrolidone (NMP) solvent, and mixed to obtain a slurry. The slurry was applied on a Cu foil as the current collector and dried at 100 C. in a vacuum to obtain a LiTiO electrode. A 2032-coin type lithium-ion battery was assembled using the same method as above except that the NbWTiO-1 electrode was replaced by the LiTiO electrode.
[0104] For comparison, commercially-acquired meso-carbon microbeads, conducting carbon black (super P), and polyvinylidene fluoride binder (PVDF) having a mass ratio of 90:5:5 were added into N-methyl-2-pyrrolidone (NMP) solvent, and mixed to obtain a slurry. The slurry was applied on a Cu foil as the current collector and dried at 100 C. in a vacuum to obtain a carbon electrode. A 2032-coin type lithium-ion battery was assembled using the same method as above except that the NbWTiO-1 electrode was replaced by the carbon electrode.
[0105] The electrode densities of the above electrodes were measured. The electrode densities were 3.3 g cm.sup.3 for the NbWTiO-1 electrode, 3.2 g cm.sup.3 for the NbWTiO-2 electrode, 3.3 g cm.sup.3 for the NbPO electrode, 2.7 g cm.sup.3 for the NbTiO electrode, 3.8 g cm.sup.3 for the NbWO electrode, 2.5 g cm.sup.3 for the LiTiO electrode, and 2.0 g cm.sup.3 for the carbon electrode. The results demonstrated that the electrode density of super-MIEC Nb-based electrodes is greatly enhanced compared to the two representative commercial high rate anodes, LiTiO electrode, and carbon electrode. The higher electrode density in the super-MIEC Nb-based electrodes may increase electrode energy density.
4. EXAMPLE ELECTROCHEMICAL PERFORMANCE
[0106]
[0107] Charge/discharge tests and GITT were conducted at varied current densities using a LAND battery testing system (CT-2001A).
[0108]
[0109]
[0110] Table 1 compares particle size, electrode density, and initial Coulombic efficiency of NbWTiO electrodes to other types of electrodes.
TABLE-US-00001 TABLE 1 Characterized Electrode Initial particle density Coulombic Materials size (m) (g cm.sup.3) efficiency (%) NbPO 1~3 3.3 97.2 TiNbO ~1 2.7 97.3 NbWO 2~10 3.8 94.8 NbWTiO-1 1~3 3.2 96.5 NbWTiO-2 1~2 3.3 96.0 Li.sub.4Ti.sub.5O.sub.12 0.8~3.0 2.5 97.0 Meso-carbon 16~19 2.0 88.5 microbeads
[0111] Table 2 compares the electrochemical properties of the NbWTiO-1 electrode, the NbWTiO-2 electrode, the NbPO electrode, the NbTiO electrode, and the NbWO electrode. Capacity was measured at 200 mA g.sup.1. Rate retention was defined as the ratio of capacity at 6,000 mA g.sup.1 (12 mA cm.sup.2) to capacity at 200 mA g.sup.1. Voltage was defined as average discharge voltage at 200 mA g.sup.1. Gravimetric and volumetric energy density were defined as the anode side (including active material, conductive carbon, and binder) in full cells using LiNi.sub.0.5Mn.sub.1.5O.sub.4 in the cathode and the Nb-based electrodes in the anode. Cyclability was defined as capacity retention after 1,000 cycles at 12 mA cm.sup.2 (60 C), which is a high rate.
TABLE-US-00002 TABLE 2 Capacity Gravimetric Volumetric retention Capacity Rate energy energy after 1000 at 200 mA retention Voltage density at density at cycles at g.sup.1 (mAh at 6,000 mA (V vs. 6,000 mA g.sup.1 6,000 mA 6,000 mA Materials g.sup.1) g.sup.1 (%) Li.sup.+/Li) (Wh kg.sup.1) g.sup.1 (Wh L.sup.1) g.sup.1 (%) NbWTiO electrode-1 187.1 59.0 1.57 343 1,133 79.5 NbWTiO electrode-2 204.2 67.4 1.62 422 1,350 88.7 NbPO electrode-1 209.9 69.4 1.53 470 1,550 46.8 NbTiO electrode-1 236.3 60.1 1.50 465 1,256 69.0 NbWO electrode-1 180.2 69.6 1.68 394 1,499 36.1
[0112]
[0113] The first five galvanostatic discharge/charge profile together with Coulombic efficiencies of NbWTiO-2 electrode is shown in
[0114] The first five galvanostatic discharge/charge profile together with Coulombic efficiencies of NbPO-1 electrode is shown in
[0115] The first five galvanostatic discharge/charge profiles together with Coulombic efficiencies of NbTiO-1 electrode are shown in
[0116] The first five galvanostatic discharge/charge profiles together with Coulombic efficiencies of NbWO-1 electrode are shown in
5. CONCLUSION
[0117] While various inventive embodiments have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the inventive embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the inventive teachings is/are used. Those skilled in the art will recognize or be able to ascertain, using no more than routine experimentation, many equivalents to the specific inventive embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, inventive embodiments may be practiced otherwise than as specifically described and claimed. Inventive embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the inventive scope of the present disclosure.
[0118] Also, various inventive concepts may be embodied as one or more methods, of which an example has been provided. The acts performed as part of the method may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include performing some acts simultaneously, even though shown as sequential acts in illustrative embodiments.
[0119] All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms.
[0120] The indefinite articles a and an, as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean at least one.
[0121] The phrase and/or, as used herein in the specification and in the claims, should be understood to mean either or both of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with and/or should be construed in the same fashion, i.e., one or more of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the and/or clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to A and/or B, when used in conjunction with open-ended language such as comprising can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.
[0122] As used herein in the specification and in the claims, or should be understood to have the same meaning as and/or as defined above. For example, when separating items in a list, or or and/or shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as only one of or exactly one of, or, when used in the claims, consisting of, will refer to the inclusion of exactly one element of a number or list of elements. In general, the term or as used herein shall only be interpreted as indicating exclusive alternatives (i.e., one or the other but not both) when preceded by terms of exclusivity, such as either, one of, only one of, or exactly one of. Consisting essentially of, when used in the claims, shall have its ordinary meaning as used in the field of patent law.
[0123] As used herein in the specification and in the claims, the phrase at least one, in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase at least one refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, at least one of A and B (or, equivalently, at least one of A or B, or, equivalently at least one of A and/or B) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.
[0124] In the claims, as well as in the specification above, all transitional phrases such as comprising, including, carrying, having, containing, involving, holding, composed of, and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases consisting of and consisting essentially of shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.