Electrode Assembly and Method for Manufacturing the Same
20230010746 · 2023-01-12
Assignee
Inventors
Cpc classification
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
Y02P70/50
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
H01M10/0454
ELECTRICITY
H01M10/0583
ELECTRICITY
International classification
Abstract
An electrode assembly according to an embodiment of the present invention for achieving the above object includes: a first electrode formed in the form of a single sheet and repetitively in-folded and out-folded at a predetermined interval; a second electrode provided in plurality and respectively interposed in spaces formed by folding the first electrode; a separator formed in the form of a single sheet and interposed between the first electrode and the second electrode so as to be repetitively in-folded and out-folded at a predetermined interval together with the first electrode; and a cover part configured to cover at least portions of an area, on which the separator is out-folded and an exposed surface, which is exposed to the outside together with the second electrode.
Claims
1. An electrode assembly comprising: a first electrode the form of a single sheet that is repetitively in-folded and out-folded at a predetermined interval; a plurality of second electrodes interposed in spaces formed by folding the first electrode; a separator formed in the form of a single sheet that is interposed between the first electrode and the plurality of second electrodes so as to be repetitively in-folded and out-folded at the predetermined interval together with the first electrode; and a cover part to covering exposed out-folded portions the separator and exposed end portions of the plurality of second electrodes.
2. The electrode assembly of claim 1, wherein the cover part is in the form of a single film.
3. The electrode assembly of claim 2, wherein first and second opposite ends of the cover part are attached to first and second opposite ends of the first electrode, respectively.
4. The electrode assembly of claim 1, wherein the cover part is in close contact with the exposed out-folded portions of the separator.
5. The electrode assembly of claim 1, wherein the cover part comprises at least one of: epoxy, polyimide, polyethylene terephthalate (PET), polypropylene (PP), or polytetrafluoroethylene (PTFE).
6. The electrode assembly of claim 1, wherein the first electrode is a single-sided electrode on which a first electrode active material is applied to only a first surface of a first electrode collector, and the plurality of second electrodes are each a double-sided electrode on which a second electrode active material is applied to first and second opposite surfaces of a second electrode collector.
7. The electrode assembly of claim 6, wherein each of the plurality of second electrodes is interposed only in a corresponding one of a plurality of spaces formed by in-folding the first electrode.
8. The electrode assembly of claim 6, wherein the separator is interposed between the first surface of the first electrode, to which the first electrode active material is applied, and each of the plurality of second electrodes.
9. The electrode assembly of claim 1, wherein, each location of the separator and each location of the first electrode at which a first end of each of the plurality of second electrodes is disposed is in-folded, and each location of the separator and each location of the first electrode at which a second end of each of the plurality of second electrodes is disposed is out-folded.
10. The electrode assembly of claim 9, wherein the exposed end portions of the plurality of second electrodes that is covered by the cover part is the second end of each of the plurality of second electrodes.
11. A method for manufacturing an electrode assembly, the method comprising: stacking a separator in the form of a single sheet on a first surface of a first electrode in the form of a single sheet; seating a plurality of second electrodes on the separator, the plurality of second electrodes spaced a predetermined interval from each other on the separator so as to form an electrode stack; in folding and out-folding the first electrode and the separator to fold the electrode stack; and covering exposed out-folded portions of the separator and exposed end portions of the plurality of second electrodes with a cover part.
12. The method of claim 11, wherein the covering of the exposed out-folded portions of the separator and the exposed end portions of the plurality of second electrodes with the cover part is performed by attaching first and second opposite ends of the cover part to both first and second opposite ends of the first electrode, respectively, the cover part being in the form of a single film.
13. The method of claim 11, wherein the covering of the exposed out-folded portions of the separator and the exposed end portions of the plurality of second electrodes with the cover part comprises: applying a cover material that is in a liquid state to the exposed out-folded portions of the separator and the exposed end portions of the plurality of second electrodes; and drying the cover material to form the cover part.
14. The method of claim 11, wherein, during the stacking of the separator on the first electrode, the separator is stacked on the first surface of the first electrode on which a first electrode active material is applied.
15. The method of claim 11, wherein the predetermined interval is longer than a length of each of the plurality of second electrodes in a long direction of the separator.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0035]
[0036]
[0037]
[0038]
[0039]
[0040]
[0041]
MODE FOR CARRYING OUT THE INVENTION
[0042] Advantages and features of the present invention, and implementation methods thereof will be clarified through following embodiments described with reference to the accompanying drawings. The present invention may, however be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. Further, the present invention is only defined by scopes of claims. Like reference numerals refer to like elements throughout.
[0043] Unless terms used in the present invention are defined differently, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art. Also, unless defined clearly and apparently in the description, the terms as defined in a commonly used dictionary are not ideally or excessively construed as having formal meaning.
[0044] In the following description, the technical terms are used only for explaining a specific exemplary embodiment while not limiting the present invention. In this specification, the terms of a singular form may include plural forms unless specifically mentioned. The meaning of “comprises” and/or “including” does not exclude other components besides a mentioned component.
[0045] Hereinafter, preferred embodiments will be described in detail with reference to the accompanying drawings.
[0046]
[0047] According to an embodiment of the present invention, since a first electrode 101 is formed in the form of a single sheet, it is unnecessary to fix the electrode to the electrode assembly by using a tape, thereby preventing the electrode from being damaged, such as an occurrence of wrinkles or swells on the electrode or deintercalation of an active material of the electrode. In addition, since the first electrode 101 is the single-sided electrode, an unnecessary electrode active material may not be formed on the outermost side of the electrode assembly 10 to improve an energy density relative to a volume. In addition, since it is unnecessary to manufacture a unit cell first, a continuous process may be easy, and a process time may be saved. In addition, since a cover part covers an area on which a separator 103 is out-folded and an exposed surface, which is exposed to the outside together with a second electrode 102, a phenomenon in which the separator 103 is rolled into a sealing part may be prevented from occurring when a degassing process is performed later.
[0048] For this, a method for manufacturing the electrode assembly 10 according to an embodiment of the present invention includes: a step of stacking the separator 103 formed in the form of a single sheet on one surface of the first electrode 101 formed in the form of a single sheet in the same direction; a step of seating a plurality of second electrodes 102 to be spaced a predetermined interval from each other on the separator 103 so as to form an electrode stack 11; a step of in-folding and out-folding the first electrode 101 and the separator 103 to fold the electrode stack 11; and a step of covering at least portions of an area, on which the separator 103 is out-folded, and an exposed surface, which is exposed to the outside together with the second electrode 102, through a cover part 104 among surfaces of the electrode stack 11.
[0049] The electrode assembly 10 manufactured through the above-described method according to an embodiment of the present invention includes a first electrode 101 formed in the form of a single sheet and repetitively in-folded and out-folded at a predetermined interval; a second electrode 102 provided in plurality and respectively interposed in spaces formed folding the first electrode 101; a separator 103 formed in the form of a single sheet and interposed between the first electrode 101 and the second electrode 102 so as to be repetitively in-folded and out-folded at a predetermined interval together with the first electrode 101; and a cover part 104 covering at least portions of an area, on which the separator 103 is out-folded and an exposed surface, which is exposed to the outside together with the second electrode 102.
[0050] As described above, in order to manufacture the electrode assembly 10, first, positive electrode active material slurry is applied to a positive electrode collector, and negative electrode active material slurry is applied to a negative electrode collector to manufacture a positive electrode and a negative electrode, respectively. The separator 103 is interposed between the positive electrode and the negative electrode, and the separator 103 and the electrodes may be stacked to manufacture the electrode assembly 10.
[0051] Both the electrodes of the positive and negative electrodes used in the present invention are not particularly limited, and the electrode active material may be prepared in a shape that is bonded to the electrode collector according to the typical method that is known in the art. Here, the positive electrode may be manufactured by, for example, applying slurry, in which a positive electrode active material, a conductive agent, and a binder are mixed, onto a positive electrode collector, and then drying and pressing the slurry. At this time, if necessary, the slurry may further include a filler. The positive electrode may be manufactured in the form of a sheet and mounted on a roll.
[0052] The positive electrode collector generally has a thickness of 3 μm to 500 μm. The positive electrode collector is usually made of a material having high conductivity without causing a chemical change. Such a material may be surface-treated with, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel on which carbon, nickel, titanium, silver, or the like is surface-treated on a surface thereof, but is not limited thereto. Also, the positive electrode collector may form a fine unevenness on a surface thereof to increase in adhesion of the positive electrode active material. Also, the positive electrode collector may have various shapes such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, and the like.
[0053] In a case of a lithium secondary battery, the positive electrode active material may include, for example, a layered compound of lithium cobalt oxide (LiCoO.sub.2), lithium nickel oxide (LiNiO.sub.2), etc., or a substituted compound with one or more transition metals; lithium manganese oxide such as Li.sub.1+xMn.sub.2−xO.sub.4 (x is 0 to 0.33), LiMnO.sub.3, LiMn.sub.2O.sub.3, LiMnO.sub.2, etc.; lithium copper oxide (Li.sub.2CuO.sub.2); vanadium oxide such as LiV.sub.3O.sub.8, LiFe.sub.3O.sub.4, V.sub.2O.sub.5, Cu.sub.2V.sub.2O.sub.7, etc.; Ni site-type lithium nickel oxide represented by Chemical Formula of LiNi.sub.1−xM.sub.xO.sub.2 (M═Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x=0.01 to 0.3); lithium manganese complex oxide represented by Chemical Formula LiMn.sub.2−xM.sub.xO.sub.2 (M═Co, Ni, Fe, Cr, Zn or Ta, and x=0.01 to 0.1) or Li.sub.2Mn.sub.3MO.sub.8 (M═Fe, Co, Ni, Cu or Zn); LiMn.sub.2O.sub.4 in which a portion of Li is substituted with alkaline earth ions; a disulfide compound; Fe.sub.2(MoO.sub.4).sub.3, and the like. However, this embodiment is not limited thereto.
[0054] The conductive agent is generally added at 1 wt % to 50 wt % based on the total weight of the mixture including the positive electrode active material. The conductive agent is usually made of a material having conductivity without causing a chemical change. The conductive agent may include, for example, conductive materials such as: graphite such as natural graphite and artificial graphite; carbon black such as acetylene black, Ketjen black, furnace black, channel black, lamp black, and thermal black; conductive fiber such as carbon fiber and metal fiber; metal powder such as carbon fluorine, aluminum, and nickel powder; conductive whisker such as zinc oxide and potassium titanate; conductive oxide such as titanium oxide; or polyphenylene derivatives.
[0055] The binder is a component assisting the bonding of the active material to the conductive agent and the bonding to the collector and is commonly added at 1 wt % to 50 wt % based on the total weight of the mixture including the positive electrode active material. Examples of the binder may include polyfluoro vinylidene, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene butadiene rubber, fluorine rubber, various copolymers, and the like.
[0056] The filler is optionally used as a component that inhibits expansion of the positive electrode. Also, a general filler may be used if the filler is a fibrous material without causing the chemical change. Examples of the filler may include olefin polymers such as polyethylene and polypropylene; and fibrous materials such as glass fibers and carbon fibers.
[0057] The negative electrode may be manufactured by, for example, applying the negative electrode active material onto the negative electrode collector and then drying and pressing the negative electrode active material. If necessary, the negative electrode active material may optionally include the conductive agent, the binder, the filler, and the like. The negative electrode may be manufactured in the form of a sheet and mounted on a roll.
[0058] The negative electrode collector generally has a thickness of 3 μm to 500 μm. The negative electrode collector is usually made of a material having conductivity without causing a chemical change. Examples of the material include copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel on which carbon, nickel, titanium, silver, or the like is surface-treated on a surface thereof, or aluminum-cadmium alloys. Also, the negative electrode collector may form a fine unevenness on the surface thereof to increase in bonding force of the negative electrode active material. Also, the negative electrode collector may have various shapes such as a film, a sheet, a foil, a net, a porous body, a foam, or a non-woven fabric.
[0059] The negative electrode active material may include, for example, carbon such as non-graphitized carbon, graphite-based carbon, etc.; a metal complex oxide such as LixFe.sub.2O.sub.3 (0≤x≤1), Li.sub.xWO.sub.2 (0≤x≤1), Sn.sub.xMe.sub.1−xMe′.sub.yO.sub.z (Me: Mn, Fe, Pb, Ge; Me′: Al, B, P, Si, elements found in Group 1, Group 2 and Group 3 in a periodic table, halogen; 0<x≤1; 1≤y≤3; 1≤z≤8), etc.; a lithium metal; a lithium alloy; a silicon-based alloy; a tin-based alloy; a metal oxide such as SnO, SnO.sub.2, PbO, PbO.sub.2, Pb.sub.2O.sub.3, Sb.sub.2O.sub.3, Sb.sub.2O.sub.4, Sb.sub.2O.sub.5, GeO, GeO.sub.2, Bi.sub.2O.sub.3, Bi.sub.2O.sub.4, Bi.sub.2O.sub.5, etc.; a conductive polymer such as polyacetylene, etc.; Li-Co-Ni-based material, and the like.
[0060] A commonly known polyolefin-based separator 103 or a composite separator 103 in which an organic and inorganic composite layer is formed on the olefin-based material may be used as the separator 103, which is disposed between the positive electrode and the negative electrode to insulate the electrodes from each other, but is not particularly limited.
[0061] The electrode assembly 10 having the above structure is accommodated in a battery case. Then, an electrolyte is injected, and the battery case is sealed to manufacture a secondary battery.
[0062] According to an embodiment of the present invention, the first electrode 101 may be a positive electrode, and the second electrode 102 may be a negative electrode, but are not limited thereto. For example, the first electrode 101 may be a negative electrode, and the second electrode 102 may be a positive electrode.
[0063] First, as illustrated in
[0064] Then, the plurality of second electrodes 102 are seated to be spaced a predetermined interval from each other on the separator 103 to form an electrode stack 11. Here, the second electrode 102 is a double-sided electrode in which the second electrode active material 1022 is applied to all both surfaces of the second electrode collector 1021. Thus, the second electrode active material 1022 is formed on both one side and the other side of the second electrode 102.
[0065] It is preferable that the predetermined interval is longer than a length of the second electrode 102. If the predetermined interval is shorter than the length of the second electrode 102, when the electrode stack 11 is folded later, the second electrode 102 is not evenly aligned and thus protrudes outward. However, if the predetermined interval is longer than the length of the second electrode 102, the second electrode 102 is evenly aligned to reduce a volume, and an area on which the second electrode 102 and the first electrode 101 overlap each other increase to increase in energy density.
[0066]
[0067] As illustrated in
[0068] Herein, the in-folding refers to folding in a direction in which the first electrode 101 surrounds the second electrode 102. Thus, when the in-folding is performed, the separator 103 and the first electrode 101 are sequentially stacked on both the surfaces of the second electrode 102. Also, the out-folding refers to folding in a direction in which the first electrode 101 excludes the second electrode 102 as the contrary concept of the in-folding. Thus, when the out-folding is performed, the first electrode collectors 1011, which are exposed through the other surface of the first electrode 101, are stacked on each other. As illustrated in
[0069]
[0070] As illustrated in
[0071] The electrode assembly 10 includes the first electrode 101, the second electrode 102, the separator 103, and the cover part 104.
[0072] The first electrode 101 is a single-sided electrode on which the first electrode active material 1012 is applied to only one surface of the first electrode collector 1011, is formed in the form of a single sheet, and repetitively in-folded and out-folded at a predetermined interval.
[0073] The second electrode 102 is a double-sided electrode on which the second electrode active material 1022 is applied to both the surfaces of the second electrode collector 1021, is provided in plurality, and is interposed in a space formed by folding the first electrode 101. Particularly, it is preferable that the second electrode 102 be interposed only in a space formed by in-folding the first electrode 101.
[0074] The separator 103 is formed in the form of a single sheet, is interposed between the first electrode 101 and the second electrode 102, and repetitively in-folded and out-folded at a predetermined interval together with the first electrode 101. Particularly, the separator 103 is interposed between one surface of the first electrode 102, to which the first electrode active material 1012 is applied, and the second electrode 102.
[0075] In general, both the outermost surfaces of the electrode assembly 10 are not used to generate electricity. However, in the electrode assembly 10 according to an embodiment of the present invention, as illustrated in
[0076] However, according to an embodiment of the present invention, since the electrode collectors are also staked on each other at the out-folded portion of the first electrode 101, the out-folded portion is not used to generate electricity. However, in general, the electrode active material is much thicker than the electrode collector in the electrode. Thus, even if the out-folded portion of the first electrode 101 does not generate electricity, the thickness is much thinner to reduce the volume. That is, the energy density relative to the volume may be further improved.
[0077] In addition, since the first electrode 101 and the separator 103 are formed in the form of a single sheet, it is unnecessary to fix the electrode to the electrode assembly by using a tape, thereby preventing the electrode from being damaged, such as an occurrence of wrinkles or swells on the electrode or deintercalation of the active material of the electrode. In addition, since it is unnecessary to manufacture a unit cell first, a continuous process may be easy, and a process time may be saved.
[0078] In the first electrode 101 and the separator 103, each of the areas I.A on which one end of the second electrode 102 is disposed is in-folded, and each of the areas O.A on which the other end 1024 of the second electrode 102 is out-folded. Thus, the areas O.A on which the separator 103 is out-folded and the other end 1024 of the second electrode 102 are exposed to the outside.
[0079] Among the plurality of surfaces constituting the completely folded electrode stack 11, the areas OA on which the separator 103 is out-folded and the other end 1024 of the second electrode 102 are provided in plurality on the exposed surface and thus are disposed alternately to be exposed together to the outside. Furthermore, as illustrated in
[0080] The cover part 104 covers at least a portion of the exposed surface. In particular, in order to prevent the separator 103 and the electrode from being damaged, it is preferable to cover the entire exposed surface. Here, the cover part 104 may be formed in the form of a single film. Also, both ends of the cover part 104 may be attached to both ends of the first electrode 101 to cover the exposed surface. As a result, it is possible to prevent the phenomenon, in which the separator 103 is rolled into the sealing part during the degassing process later, from occurring. However, the present invention is not limited thereto, and the cover part 104 has a shape constituted by a plurality of films and may be attached to be spaced apart from each other on the exposed surface of the electrode stack 11 in a longitudinal length direction of the electrode stack 11. Here, as the spaced interval is narrowed, the phenomenon, in which the separator 103 is rolled into the sealing part, may be reliably prevented from occurring.
[0081] As illustrated in
[0082] The cover part 104 may include at least one of insulating materials such as epoxy, polyimide, polyethylene terephthalate (PET), polypropylene (PP), and polytetrafluoroethylene (PTFE). Thus, even if the electrode is damaged, defective insulation between the first electrode 101 and the second electrode 102 may be prevented.
[0083]
[0084] According to another embodiment of the present invention, when at least a portion of an exposed surface is covered with a cover part 104a, a cover material that is in a liquid state may be applied to at least a portion of the exposed surface. In addition, the cover part 104a may be formed by drying the cover material. Since the cover part 104a is completely in close contact with the exposed surface, it is possible to prevent not only a separator 103 but also the cover part 104a from being rolled into a sealing part during a degassing process later.
[0085] Those with ordinary skill in the technical field of the present invention pertains will be understood that the present invention can be carried out in other specific forms without changing the technical idea or essential features. Therefore, the above-disclosed embodiments are to be considered illustrative and not restrictive. Accordingly, the scope of the present invention is defined by the appended claims rather than the foregoing description and the exemplary embodiments described therein. Various modifications made within the meaning of an equivalent of the claims of the invention and within the claims are to be regarded to be in the scope of the present invention.
DESCRIPTION OF THE SYMBOLS
[0086] 10, 30: Electrode assembly 11: Electrode stack
[0087] 101: First electrode 1011: First electrode collector
[0088] 1012: First electrode active material 102: Second electrode
[0089] 1021: Second electrode collector 1022: Second electrode active material
[0090] 1023: One end of second electrode 1024: The other end of second electrode
[0091] 103: Separator104: Cover part
[0092] 31: Tape