Electrode assembly including a positive electrode with an insulating coating layer and method for manufacturing the same

Abstract

The present invention relates to an electrode assembly including a positive electrode having an insulating coating layer and a method for manufacturing the same, and specifically relates to an electrode assembly including one or more first monocells; and a second monocell laminated on the uppermost part of the first monocell; wherein the second monocell is provided with an insulating coating layer, and a method for manufacturing the same.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0056601 filed on April 28, 2023 and Korean Patent Application No. 10-2024-0021296 filed on February 14, 2024, and all the contents disclosed in the documents of the Korean patent applications are included as part of this specification.

[0002] The present invention relates to an electrode assembly including a positive electrode having an insulating coating layer and a method for manufacturing the same, and more specifically, to an electrode assembly including a positive electrode having an insulating coating layer and a method for manufacturing the same, which enable a stable manufacturing process and can increase energy density.

Background Art

[0003] In recent years, there has been an increasing demand for secondary batteries that can store electrical energy produced by the development of alternative energy due to air pollution caused by the use of fossil fuels and the depletion of energy. Secondary batteries that can be charged and discharged are closely used in daily life, such as being used in mobile devices, electric vehicles, hybrid electric vehicles, etc.

[0004] Secondary batteries used as an energy source for various essential electronic devices in modern society are increasing in capacity required by the increasing usage and complexity of mobile devices and the development of electric vehicles, etc. To meet the needs of users, a large number of battery cells are arranged in small devices, but in vehicles, etc., a battery module that electrically connects a large number of battery cells or a battery pack including a large number of such battery modules is used.

[0005] On the other hand, as shown in FIG. 1 which is a cross-sectional view of an electrode stack part according to the prior art, an electrode assembly accommodated in a cell case is generally configured by sequentially stacking a plurality of monocells M arranged in the order of a separator 30, a negative electrode 20, a separator 30, and a positive electrode 10, and one half-cell H arranged in the order of a separator 30, a negative electrode 20, and a separator 30.

[0006] However, the half-cell located at the top of the electrode assembly consists of a separation membrane, a negative electrode, and another separation membrane, and is thinner than the monocell, making transportation and stacking difficult. This is likely to lead to reduced efficiency in the production process and defective products.

[0007] Furthermore, after stacking multiple monocells and one halfcell, a step must be taken to cover the electrode assembly with a separate insulating material, such as a separator film, to ensure insulation from the cell case. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Korean Published Patent No. 10-2015-0100017 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] To solve the above-mentioned problems, the present invention aims to provide an electrode assembly including a positive electrode equipped with an insulating coating layer that enables a stable production process, and a method for manufacturing the same.

[0010] Furthermore, the present invention aims to provide an electrode assembly including a positive electrode equipped with an insulating coating layer that can reduce the number of unit production processes and improve production efficiency, and a method for manufacturing the same. [Means for solving the problem]

[0011] An electrode assembly according to the present invention for achieving the above-mentioned objectives comprises one or more first monocells and a second monocell laminated on top of the first monocells, wherein the second monocell is provided with an insulating coating layer.

[0012] Furthermore, in the electrode assembly according to the present invention, the insulating coating layer is characterized in that it is made of one or more of polyethylene terephthalate (PET), polypropylene (PP), and ceramic.

[0013] Furthermore, in the electrode assembly according to the present invention, the insulating coating layer is characterized by being ceramic.

[0014] Furthermore, in the electrode assembly according to the present invention, the second monocell is characterized in that a second separator membrane, a second negative electrode, a second separator membrane, and a second positive electrode are stacked in that order from the bottom, and the insulating coating layer is provided on the second positive electrode.

[0015] Furthermore, in the electrode assembly according to the present invention, the second positive electrode is characterized in that the second positive electrode active material, the second positive electrode current collector, and the insulating coating layer are stacked in that order from the bottom.

[0016] Furthermore, the electrode assembly according to the present invention is characterized in that the thickness of the second monocell is in the range of 150 μm to 250 μm.

[0017] Furthermore, the electrode assembly according to the present invention is characterized in that the thickness of the insulating coating layer is in the range of 10 μm to 20 μm.

[0018] Furthermore, in the electrode assembly according to the present invention, the first monocell is characterized in that a first separation membrane, a first negative electrode, a first separation membrane, and a first positive electrode are stacked in that order from the bottom, and one or more of the first negative electrode and the second negative electrode for lithium ion storage contain silicon.

[0019] Furthermore, in the electrode assembly according to the present invention, the silicon is characterized in that it is 95% by weight or more when based on the negative electrode active material.

[0020] Furthermore, the electrode assembly according to the present invention is characterized in that the thickness of the first monocell is in the range of 150 μm to 250 μm.

[0021] In the electrode assembly according to the present invention, the thickness of the first monocell is in the range of 150 μm to 200 μm.

[0022] Further, the present invention can be a battery cell including the above-described electrode assembly.

[0023] The method for manufacturing an electrode assembly according to the present invention includes: a first step of preparing one or more first monocells and a second monocell; and a second step of sequentially laminating one or more first monocells and one second monocell from below. The first monocell is laminated in the order of a first separator, a first negative electrode, a first separator, and a first positive electrode from below. The second monocell is laminated in the order of a second separator, a second negative electrode, a second separator, and a second positive electrode from below. The second positive electrode is composed of a second positive electrode current collector, a second positive electrode active material on the lower surface of the second positive electrode current collector, and an insulating coating layer on the upper surface of the second positive electrode current collector.

[0024] In the method for manufacturing an electrode assembly according to the present invention, the insulating coating layer is ceramic.

[0025] In the method for manufacturing an electrode assembly according to the present invention, one or more of the first negative electrode and the second negative electrode contain silicon.

Advantages of the Invention

[0026] As described above, an insulating coating layer is located at the uppermost part of the second positive electrode constituting the second monocell of the electrode assembly according to the present invention. This has the advantage that the insulation state between the electrode assembly and the battery case can be maintained without a separate separator covering the entire electrode assembly, contributing to the simplification of the production process and the reduction of manufacturing costs.

[0027] Furthermore, when the uppermost insulating coating layer of the second positive electrode constituting the second monocell of the electrode assembly according to the present invention is made of ceramic, the bending or sagging of the second positive electrode and the second monocell can be minimized, which has the advantage of making the transportation and stacking of these second positive electrodes and second monocells very easy.

[0028] Furthermore, since the negative electrode active material of the electrode assembly according to the present invention is mainly composed of silicon-based negative electrode active material, it has the advantage of being able to increase the lithium ion storage capacity and improve energy density. [Brief explanation of the drawing]

[0029] [Figure 1] This is a cross-sectional view of an electrode stack according to the prior art. [Figure 2] This is an exploded cross-sectional view of an electrode assembly according to a preferred embodiment of the present invention. [Figure 3] This is an enlarged cross-sectional view of a first monocell according to a preferred embodiment of the present invention. [Figure 4] This is an enlarged cross-sectional view of a second monocell according to a preferred embodiment of the present invention. [Modes for carrying out the invention]

[0030] Hereinafter, with reference to the attached drawings, embodiments that allow a person with ordinary skill in the art to carry out the present invention will be described in detail. However, in describing the operating principle of a preferred embodiment of the present invention in detail, if it is determined that a specific description of a related known function or configuration may obscure the gist of the present invention, such a detailed description will be omitted.

[0031] Furthermore, the same reference numerals shall be used for similar functional and operating parts throughout the drawings. Throughout the specification, when one part is said to be connected to another part, this includes not only direct connection but also indirect connection through other elements in between. Also, the inclusion of one component does not exclude other components unless otherwise stated, but rather means that other components may be included.

[0032] The electrode assembly including a positive electrode equipped with an insulating coating layer according to the present invention and its manufacturing method will be described below with reference to the attached drawings.

[0033] Figure 2 is an exploded cross-sectional view of an electrode assembly according to a preferred embodiment of the present invention, Figure 3 is an enlarged cross-sectional view of a first monocell according to a preferred embodiment of the present invention, and Figure 4 is an enlarged cross-sectional view of a second monocell according to a preferred embodiment of the present invention.

[0034] Referring to Figures 2 to 4, the electrode assembly according to the present invention includes one or more first monocells 100 and one second monocell 200, in which case the first monocell 100 is located at the bottom and the second monocell 200 is located at the outermost part of the top.

[0035] First, the first monocell 100 has a configuration substantially identical to a commonly known monocell consisting of two separation membranes, one negative electrode, and one positive electrode. That is, the first monocell 100 is stacked from bottom to top in the order of first separation membrane 110, first negative electrode 120, first separation membrane 110, and first positive electrode 130.

[0036] The first separation membrane 110 is located on the lower surface of the first negative electrode 120 and between the upper surface of the first negative electrode 120 and the lower surface of the first positive electrode 130, respectively, and plays a role in preventing a short circuit between the first negative electrode 120 and the first positive electrode 130, thereby allowing only the movement of lithium ions.

[0037] The material of such a first separation membrane 110 is preferably one selected from polyethylene, polypropylene, polyethylene / polypropylene double layer, polyethylene / polypropylene / polyethylene triple layer, polypropylene / polyethylene / polypropylene triple layer, and organic fiber filter paper, but is not limited thereto.

[0038] The first negative electrode 120 includes a first negative electrode current collector 121 and a first negative electrode active material 122 applied to the lower and upper surfaces of the first negative electrode current collector 121, respectively.

[0039] The first negative electrode current collector 121 is generally made with a thickness of 3 μm to 500 μm. Such a first negative electrode current collector 121 is not particularly limited as long as it does not induce chemical changes in the battery and is conductive. For example, the first negative electrode current collector 121 can be made of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., or aluminum-cadmium alloy.

[0040] Furthermore, the first negative electrode current collector 121 can form fine irregularities on its surface to strengthen the bonding force of the negative electrode active material, and can be used in a variety of forms such as films, sheets, foils, nets, porous materials, foams, and nonwoven fabrics.

[0041] The first negative electrode active material 122 for lithium ion storage may contain graphite, silicon-based materials, and / or lithium metal, or the negative electrode active material may consist almost entirely of silicon. For example, silicon is preferably 95% by weight or more, and more preferably 99% by weight, relative to the negative electrode active material.

[0042] The silicon-based negative electrode active material may be one or more of Si, SiO, SiO2, and nanosilicon composites. The nanosilicon composite may be one of any silicon alloy. Furthermore, the metallic elements contained in the silicon alloy may be at least one of Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, Se, Te, and Po.

[0043] Of course, conductive material and binder can be additionally mixed into the first negative electrode active material 122, and these can be coated onto the first negative electrode current collector 121.

[0044] The conductive material is a component used to further improve the conductivity of the negative electrode active material. Examples of conductive materials that can be used in certain proportions include carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0045] The binder is a component that assists in the bonding of the negative electrode active material to conductive materials and to the current collector, and may include at least one selected from the group consisting of styrene butadiene rubber (SBR), acrylonitrile butadiene rubber, acrylic rubber, butyl rubber, fluororubber, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinyl alcohol (PVA), polyacrylic acid (PAA), polyethylene glycol (PEG), polyacrylonitrile (PAN), and polyacrylamide (PAM).

[0046] When a silicon-based negative electrode active material is used for lithium ion storage, it can store more lithium ions per unit area than conventional graphite-centered negative electrode active materials. This improves energy density, which has the advantage of contributing to a reduction in the overall volume of the electrode assembly.

[0047] The first positive electrode 130 comprises a first positive electrode current collector 131 and a first positive electrode active material 132 applied to the upper and lower surfaces of the first positive electrode current collector 131, respectively.

[0048] The first positive electrode current collector 131 can generally have a thickness of 3 μm to 500 μm. It is not particularly limited as long as it does not induce chemical changes in the battery and has high conductivity. For example, the first positive electrode current collector 131 can be made of stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel with a surface treatment of carbon, nickel, titanium, silver, etc. Furthermore, to enhance the adhesion of the positive electrode active material, the surface may have fine irregularities, or various forms such as films, sheets, foils, nets, porous materials, foams, and nonwoven fabrics can be used.

[0049] The first positive electrode active material 132 is a layered compound such as lithium cobalt oxide (LiCoO2) or lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; chemical formula Li 1+x Mn 2-x Lithium manganese oxides such as O4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, Cu2V2O7; chemical formula LiNi 1-x M x Ni-site type lithium nickel oxide represented as O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x = 0.01 to 0.3); chemical formula LiMn 2-x M x Lithium manganese complex oxides represented as O2 (where M = Co, Ni, Fe, Cr, Zn, or Ta, and x = 0.01 to 0.1) or Li2Mn3MO8 (where M = Fe, Co, Ni, Cu, or Zn); LiMn2O4, where part of the Li in the chemical formula is substituted with an alkaline earth metal ion; disulfide compounds; Fe2(MoO4)3, LiNi x Mn 2-x You can use formulas like O4 (0.01 ≤ x ≤ 0.6).

[0050] On the other hand, conductive materials and binders can be mixed with the first positive electrode active material 132, and fillers may be added as needed.

[0051] The conductive material is usually added in an amount of 1% to 50% by weight based on the total weight of the mixture containing the first positive electrode active material 132. Such conductive materials are not particularly limited as long as they do not induce chemical changes in the battery and are conductive. Examples of conductive materials that can be used include graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0052] The binder is a component that assists in the bonding of the first positive electrode active material 132 to conductive materials and to the current collector, and is usually added at a concentration of 1% to 50% by weight based on the total weight of the mixture containing the first positive electrode active material 132. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butylene rubber, fluororubber, and various copolymers.

[0053] The thickness of the first monocell 100, which includes the above-described configurations, is 400 μm or less, preferably in the range of 150 μm to 250 μm, and more preferably in the range of 150 μm to 200 μm.

[0054] The second monocell 200 has a structure similar to the first monocell 100, and is stacked in the order of second separation membrane 210, second negative electrode 220, second separation membrane 210, and second positive electrode 230 from the bottom.

[0055] Here, the second separation membrane 210 may be identical to the first separation membrane 110 of the first monocell 100 described above. Also, the second negative electrode 220 may have the same configuration as the first negative electrode 120 described above, so redundant explanations are omitted.

[0056] The second positive electrode 230 includes a second positive electrode current collector 231, a second positive electrode active material 232 applied to the lower surface of the second positive electrode current collector 231, and an insulating coating layer 233 located on the upper surface of the second positive electrode current collector 231.

[0057] The second positive electrode current collector 231 and the second positive electrode active material 232 may have the same configuration as the first positive electrode current collector 131 and the first positive electrode active material 132 described above.

[0058] The insulating coating layer 233 located on the upper surface of the second positive electrode current collector 231, that is, at the top of the outermost casing of the electrode assembly, may be made of an insulating material.

[0059] The material of such an insulating coating layer 233 is preferably selected from one or more of polyethylene terephthalate (PET), polypropylene (PP), and ceramic, and more preferably polypropylene (PP) or ceramic.

[0060] In particular, the material of the insulating coating layer 233 is most preferably ceramic, because the formation of the ceramic coating layer improves the mechanical strength of the second positive electrode 230 and allows it to maintain a certain degree of rigidity, thus facilitating the transportation and stacking of the second positive electrode 230.

[0061] Here, the thickness of the insulating coating layer 233 is preferably in the range of 10 μm to 20 μm.

[0062] When the surface exposed to the outside while located at the uppermost outer casing of the electrode assembly is formed with an insulating coating layer 233, the insulating state between the electrode assembly and the battery case can be maintained without a separate separator film covering the entire electrode assembly.

[0063] Furthermore, while a conventional electrode assembly has a half-cell composed of a separation membrane, a negative electrode, and another separation membrane at its uppermost end, in the present invention, a second positive electrode is additionally provided on the upper surface of the separation membrane, with a second positive electrode active material coated on its lower surface and an insulating coating layer on its upper surface, relative to the second positive electrode current collector. Therefore, the thickness of the half-cell is increased compared to a conventional half-cell, which has the advantage of stabilizing processes such as half-cell transport and lamination.

[0064] On the other hand, the thickness of the second monocell 200, which includes the above-described configurations, is 400 μm or less, preferably in the range of 150 μm to 250 μm, and more preferably in the range of 150 μm or more and less than 200 μm.

[0065] The method for manufacturing an electrode assembly according to the present invention, having the above-described configuration, comprises a first step of preparing one or more first monocells 100 and second monocells 200, and a second step of sequentially stacking one or more first monocells 100 and second monocells 200 from the bottom.

[0066] As described above, the first monocell 100 has a structure in which the first separation membrane 110, the first negative electrode 120, the first separation membrane 110, and the first positive electrode 130 are stacked in that order from the bottom, while the second monocell 200 has a structure in which the second separation membrane 210, the second negative electrode 220, the second separation membrane 210, and the second positive electrode 230 are stacked in that order from the bottom.

[0067] The detailed configurations of the first separation membrane 110, first negative electrode 120, first separation membrane 110 and first positive electrode 130 constituting the first monocell 100, and the second separation membrane 210, second negative electrode 220, second separation membrane 210 and second positive electrode 230 constituting the second monocell 200 are as described above, so redundant explanations will be omitted.

[0068] The present invention may be a pouch-type secondary battery containing the electrode assembly described above. Alternatively, the present invention may be a battery module or battery pack including the secondary battery described above.

[0069] A person with ordinary skill in the field to which this invention belongs will be able to make various applications and modifications within the scope of this invention based on the above content. [Explanation of Symbols]

[0070] 100 First Monocell 110 First separation membrane 120 First negative electrode 121 First negative electrode current collector 122 First negative electrode active material 130 First positive electrode 131 First positive electrode current collector 132 First positive electrode active material 200 Second Monocell 210 Second separation membrane 220 Second negative electrode 221 2nd negative electrode current collector 222 Second negative electrode active material 230 Second positive electrode 231 Second positive electrode current collector 232 Second positive electrode active material 233 Insulating coating layer

Claims

1. One or more first monocells, The first monocell includes a second monocell stacked on top of the first monocell, The second monocell is provided with an insulating coating layer. The second monocell is constructed by stacking a second separator membrane, a second negative electrode, a second separator membrane, and a second positive electrode in that order from the bottom, and the insulating coating layer is provided on the second positive electrode. The second positive electrode is an electrode assembly comprising a second positive electrode current collector, a second positive electrode active material on the lower surface of the second positive electrode current collector, and an insulating coating layer formed only on the upper surface of the second positive electrode current collector.

2. The electrode assembly according to claim 1, wherein the insulating coating layer is one or more of polyethylene terephthalate (PET), polypropylene (PP), and ceramic.

3. The electrode assembly according to claim 2, wherein the insulating coating layer is ceramic.

4. The electrode assembly according to claim 1, wherein the second positive electrode is laminated in the order of second positive electrode active material, second positive electrode current collector, and insulating coating layer from the bottom.

5. The electrode assembly according to claim 3, wherein the thickness of the second monocell is in the range of 150 μm to 250 μm.

6. The electrode assembly according to claim 5, wherein the thickness of the insulating coating layer is in the range of 10 μm to 20 μm.

7. The electrode assembly according to claim 1, wherein the first monocell is stacked from the bottom in the order of a first separation membrane, a first negative electrode, a first separation membrane, and a first positive electrode, and one or more of the first negative electrode and the second negative electrode for lithium ion storage contains silicon.

8. The electrode assembly according to claim 7, wherein the silicon is 95% by weight or more, based on the negative electrode active material.

9. The electrode assembly according to claim 7, wherein the thickness of the first monocell is in the range of 150 μm to 250 μm.

10. The electrode assembly according to claim 9, wherein the thickness of the first monocell is in the range of 150 μm to 200 μm.

11. A battery cell comprising an electrode assembly according to any one of claims 1 to 10.

12. A battery module comprising the battery cell described in claim 11.

13. The first step involves preparing one or more first monocells and second monocells, The second step includes sequentially stacking one or more first monocells and one second monocell from the bottom, The first monocell is stacked in the following order from the bottom: first separation membrane, first negative electrode, first separation membrane, and first positive electrode. The second monocell is stacked in the following order from the bottom: second separator membrane, second negative electrode, second separator membrane, and second positive electrode. A method for manufacturing an electrode assembly, wherein the second positive electrode comprises a second positive electrode current collector, a second positive electrode active material on the lower surface of the second positive electrode current collector, and an insulating coating layer formed only on the upper surface of the second positive electrode current collector.

14. The method for manufacturing an electrode assembly according to claim 13, wherein the insulating coating layer is ceramic.

15. The method for manufacturing an electrode assembly according to claim 14, wherein one or more of the first negative electrode and the second negative electrode contain silicon.

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