Electrode assembly and electrochemical device comprising same

Abstract

The present invention provides an electrode assembly including a negative electrode current-collecting structure and multiple electrode stacks, wherein: each electrode stack has a structure in which a negative electrode, a solid electrolyte, a double-sided positive electrode, a solid electrolyte, and a negative electrode are sequentially stacked; the negative electrode current-collecting structure includes a negative electrode current collector and multiple insulating layers stacked on the negative electrode current collector to be spaced apart from each other and is bent in a zigzag manner such that a portion in which the insulating layers are stacked forms a folding portion and a portion in which the insulating layers are not stacked forms a horizontal stack portion; one electrode stack is inserted and stacked between the adjacent stack portions; and the insulating layer is positioned on the inner side of the folding portion so as to face the electrode stack.

Description

Electrode assembly and electrochemical device including the same

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0079378, dated June 19, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to an electrode assembly and an electrochemical device including the same.

[0003]

[0004] Interest in energy storage technology has been growing steadily. As applications expand to include cell phones, camcorders, laptops, and even electric vehicles, research and development efforts on batteries are becoming increasingly concrete. Electrochemical devices are receiving the most attention in this regard, and with the recent trend toward miniaturization and lightweighting of electronic devices, the development of secondary batteries, which are compact, lightweight, and capable of high-capacity recharge and discharge, is becoming a focus of attention.

[0005] Additionally, secondary batteries are also classified based on the structure of the electrode assembly of the positive electrode / separator / cathode structure. Representative examples of electrode assemblies include jelly-roll electrode assemblies, which are structures in which long sheet-shaped positive and negative electrodes are rolled up with a separator between them, and stacked electrode assemblies, which are structures in which multiple positive and negative electrodes cut into units of a predetermined size are sequentially stacked with a separator between them.

[0006] However, these conventional electrode assemblies have several problems.

[0007] First, the jelly-roll electrode assembly is made by tightly winding long sheet-shaped positive and negative electrodes into a cylindrical or oval cross-section. In this structure, stress caused by expansion and contraction of the electrodes during charging and discharging accumulates inside the electrode assembly, and when the stress accumulation exceeds a certain limit, deformation of the electrode assembly occurs. Furthermore, the deformation of the electrode assembly may cause an uneven gap between the electrodes, which may rapidly reduce the performance of the battery and lead to a problem of threatening the safety of the battery due to an internal short circuit. In addition, since the jelly-roll electrode assembly must wind long sheet-shaped positive and negative electrodes, it is difficult to quickly wind the assembly while maintaining a constant gap between the positive and negative electrodes, which also leads to a problem of reduced productivity.

[0008] Second, the stacked electrode assembly requires sequentially stacking a plurality of positive and negative electrode units. This requires a separate transfer process for the electrode plates for manufacturing the units, and the sequential stacking process requires significant time and effort, resulting in low productivity.

[0009] To solve these problems, an advanced stack-folding electrode assembly, which is a hybrid of the jelly-roll type and the stack type, has been developed. The stack-folding electrode assembly has a structure in which bi-cells or full cells, which are stacked with a separator interposed between a predetermined number of positive and negative electrodes, are wound using a long, continuous separator sheet (folding separator).

[0010] The above stack-folding type electrode assembly generally connects the electrodes of each layer by extending a separator, which is easier to fold than the electrodes themselves. At this time, the electrodes of each layer are supplied in a cut state for forming the electrode assembly, similar to the stack-type electrode assembly.

[0011] All-solid-state batteries are batteries in which all of their components, such as electrodes and electrolytes, are solid. However, when multiple positive electrodes, negative electrodes, and solid electrolytes are sequentially stacked, which are cut into units of a predetermined size, the solid electrolyte may break or the positive electrode may spread, making it difficult to manufacture them as stacked electrode assemblies. To address these issues, stacked-folding electrode assemblies have been manufactured using insulating materials in the form of separators or films, but this has resulted in low energy density. Therefore, research into electrode assemblies that can address these issues is needed.

[0012]

[0013] [Previous literature]

[0014] [Patent Document]

[0015] Republic of Korea Publication Patent No. 10-2015-0063726

[0016]

[0017] The present invention has been devised to solve the above problems, and the purpose of the present invention is to provide an electrode assembly having excellent energy density.

[0018]

[0019] To achieve the above purpose,

[0020] The present invention relates to an electrode assembly comprising a cathode current collecting structure and a plurality of electrode stacks,

[0021] The above electrode laminate has a structure in which a cathode, a solid electrolyte, a double-sided anode, a solid electrolyte, and a cathode are laminated in that order.

[0022] The above negative electrode current collector structure includes a negative electrode current collector and a plurality of insulating layers laminated on the negative electrode current collector while being spaced apart from each other, and the portion where the insulating layers are laminated forms a folding portion, and the portion where the insulating layers are not laminated is bent in a zigzag manner to form a horizontal stack portion.

[0023] An electrode assembly is provided in which one electrode laminate is inserted and laminated between the adjacent stack portions and the stack portions, and an insulating layer is positioned on the inner side of the electrode laminate in the folding portion.

[0024] In one embodiment of the present invention, the spacing between the plurality of insulating layers is equal to the length of the stack portion, and the insulating layers may be alternately positioned on one side and the other side of the negative electrode current collector.

[0025] In one embodiment of the present invention, the length of the insulating layer may be the same as the length of the folding portion.

[0026] In one embodiment of the present invention, the stack portion may be in close contact with the cathode of the electrode laminate.

[0027] In one embodiment of the present invention, the folding portion may not be in contact with the side surface of the electrode laminate.

[0028] In one embodiment of the present invention, the negative electrode current collector may be formed continuously.

[0029] In one embodiment of the present invention, a plurality of stack portions and folding portions included in the negative electrode current collector structure may be connected alternately and continuously.

[0030] In one embodiment of the present invention, the double-sided positive electrode may include a positive electrode active material layer on both sides of the positive electrode current collector.

[0031] In one embodiment of the present invention, the negative electrode may be lithium metal.

[0032] In one embodiment of the present invention, the solid electrolyte may be a sulfide-based solid electrolyte.

[0033] In one embodiment of the present invention, the length of the solid electrolyte may be equal to or longer than the length of the negative electrode.

[0034] In one embodiment of the present invention, the length of the cathode may be equal to or longer than the length of the double-sided anode.

[0035]

[0036] In addition, the present invention may be an electrochemical device including the electrode assembly of the present invention.

[0037] In one embodiment of the present invention, the electrochemical device may be an all-solid-state battery.

[0038]

[0039] The electrode assembly of the present invention has a stable structure and can effectively secure energy density by arranging an insulating layer on the side of the electrode laminate.

[0040]

[0041] Figures 1 and 2 are schematic drawings showing the structure of an electrode assembly according to one embodiment of the present invention.

[0042] FIG. 3 is a drawing schematically showing the structure of a cathode current collector structure according to one embodiment of the present invention.

[0043] FIG. 4 is a drawing schematically showing the structure of an electrode structure according to one embodiment of the present invention.

[0044] Figure 5 is a drawing showing a manufacturing process of an electrode assembly according to one embodiment of the present invention.

[0045]

[0046] Hereinafter, specific examples will be described in detail with illustrative drawings. When assigning reference numerals to components in each drawing, it should be noted that, where possible, identical components will be assigned the same reference numerals, even if they appear in different drawings. Furthermore, when describing specific examples, if a detailed description of a related known configuration or function is deemed to hinder understanding of the specific example, such detailed description will be omitted.

[0047] When a component is described as being "connected," "coupled," or "connected" to another component, it should be understood that the component may be directly connected or connected to that other component, but that another component may also be "connected," "coupled," or "connected" between the components.

[0048] Components included in one specific example and components with common functions will be described using the same names in other specific examples. Unless otherwise stated, the descriptions given in one specific example may also apply to other specific examples, and specific descriptions will be omitted to the extent of overlap.

[0049] In this specification, the terms "length direction" and "thickness direction" are used. Drawings such as FIGS. 1 to 5 of this specification are front views, and based on the front view, the "length direction" refers to the left-right direction in the drawing, and the "thickness direction" refers to the up-down direction in the drawing.

[0050]

[0051] Figures 1 and 2 are schematic drawings showing an electrode assembly according to one embodiment of the present invention.

[0052] Referring to FIGS. 1 and 2, an electrode assembly (100) according to one embodiment of the present invention may include a negative electrode current collector structure (120) and an electrode stack (110).

[0053] The above-described negative electrode collector structure (120) may include a negative electrode current collector (121) and a plurality of insulating layers (122) positioned on the negative electrode current collector (121). The negative electrode collector structure (120) may be formed continuously, and specifically, the negative electrode current collector (121) may be formed continuously. The electrode assembly (100) includes only one negative electrode collector structure (120), and a basic electrode assembly structure such as folding the negative electrode current collector structure (120) to fix the electrode laminate (110) therein can be formed. Since the negative electrode collector (121) is formed continuously, the electrode assembly (100) according to one embodiment of the present invention has an advantageous effect in securing energy density. When manufacturing an electrode assembly by stacking a plurality of electrode laminates one by one, it is necessary to prevent the electrode laminate from warping during stacking, and an intermediate, etc., must be used for safe transport of the electrode laminate. However, the present invention can prevent distortion when stacking multiple electrode laminates by using the negative electrode current collecting structure (120), and can reduce the volume of the electrode assembly by not using an intermediate.

[0054] According to one embodiment of the present invention, the negative electrode current collecting structure (120) may include a plurality of stack portions (123) and a plurality of folding portions (124) depending on the position in the electrode assembly (100). In the negative electrode current collecting structure (120), the stack portions (123) and the folding portions (124) are units that distinguish the positions of the negative electrode current collecting structure (120). The folding portions (124) may be formed at the point where the stack portions (123) end. In addition, the stack portions (123) may be formed at the point where the folding portions (124) end.

[0055] The above stack portion (123) refers to a negative electrode current collecting structure (120) at a position where the negative electrode (111) of the electrode stack (110) is stacked, and may have a straight shape. The above folding portion (124) refers to a negative electrode current collecting structure (120) at a position connecting between the stack portions (123), and may have a curved or straight shape.

[0056] The electrode assembly (100) may have a plurality of stack portions (123) sequentially positioned side by side in the thickness direction by means of a folding portion (124), and one electrode laminate (110) may be positioned between stack portions (123) adjacent in the thickness direction. Accordingly, the electrode assembly (100) may have a structure in which the stack portions (123) of the negative electrode current collecting structure (120) and the electrode laminate (110) are alternately and sequentially stacked. In addition, the plurality of stack portions (123) and the folding portion (124) may be alternately and continuously connected, and the folding portion (124) may be folded in an opposite direction to the adjacent folding portion (124), and as a specific example, may be folded in a zigzag shape. In addition, the stack portion (123) may be in close contact with the negative electrode (111) of the electrode laminate (110).

[0057] FIG. 3 is a schematic drawing of a cathode current collector structure (120) according to one embodiment of the present invention.

[0058] Referring to FIG. 3, the stack portion (123) of the negative electrode current collector structure (120) may be formed of only the negative electrode current collector (110), and the folding portion (124) may be formed of the negative electrode current collector (110) and an insulating layer (122). That is, the portion where the insulating layer (122) is laminated may form the folding portion (124), and the portion where the insulating layer (122) is not laminated may be the stack portion (123). More specifically, in the negative electrode current collector structure (120), a plurality of insulating layers (122a, 122b) are spaced apart from each other, and the spacing distance may be the same as the distance of the stack portion (123), and the longitudinal length of the insulating layer (122) may be the same as the longitudinal length of the folding portion (124). In addition, the plurality of insulating layers (122a, 122b) may be alternately positioned on one side and the other side of the negative electrode current collector (121). The negative electrode current collector structure (120) may be manufactured by alternately coating a plurality of insulating layers (122a, 122b) on one side and the other side of the negative electrode current collector (121) having a continuous shape, and the separation distance and the longitudinal length of the insulating layers are as described above. In addition, the negative electrode current collector structure (120) may be bent in a zigzag manner so that the portion of the electrode assembly (100) where the insulating layers (122) are laminated forms a folding portion (124), and the portion where the insulating layers (122) are not laminated forms a horizontal stack portion (123).

[0059] When folding the above-described negative electrode current collector structure (120), the folding may be performed such that the insulating layer (122) is positioned on the inner side of the electrode stack (110) of the folding portion (124), and at this time, the folding may be performed such that the electrode stack (110) and the insulating layer (122) are in contact or not in contact. The length in the thickness direction of the electrode stack (110) may be the same as the length of the insulating layer (122). Therefore, the length in the thickness direction of the electrode stack (110) may be the same as the length of the folding portion (124).

[0060] An electrode assembly (100) according to one embodiment of the present invention may have a negative electrode current collector (121) positioned between a plurality of electrode laminates (110), and an insulating layer (122) positioned on a side surface of the electrode laminate (110). In addition, the insulating layer (122) may be positioned on one side surface of one electrode laminate (110) and the other side surface of another electrode laminate (110), and may be positioned alternately with each other.

[0061] FIG. 4 is a drawing schematically showing the structure of an electrode structure according to one embodiment of the present invention.

[0062] Referring to FIG. 4, the electrode laminate (110) may be laminated in the order of a cathode (111), a solid electrolyte (112), a double-sided anode (113), a solid electrolyte (112), and a cathode (111).

[0063] The above solid electrolyte (112) may include a sulfide-based solid electrolyte, and the sulfide-based solid electrolyte contains sulfur (S) and has the ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and may include Li-PS-based glass or Li-PS-based glass ceramic.

[0064] Specifically, the sulfide-based solid electrolyte may include at least one selected from the group consisting of Li6PS5Cl, Li6PS5Br, Li6PS5I, Li2S-P2S5, Li2S-LiI-P2S5, Li2S-LiI-Li2O-P2S5, Li2S-LiBr-P2S5, Li2S-Li2O-P2S5, Li2S-Li3PO4-P2S5, Li2S-P2S5, Li2S-P2S5-SiS2, Li2S-P2S5-SnS, Li2S-P2S5-Al2S3, Li2S-GeS2, and Li2S-GeS2-ZnS, and preferably may include at least one selected from the group consisting of Li6PS5Cl, Li6PS5Br, and Li6PS5I. The above Li6PS5Cl, Li6PS5Br, and Li6PS5I may be argyrodite type solid electrolytes. In addition, the sulfide-based solid electrolyte may be in a form doped with trace elements, for example, Li6PS5Cl may be additionally doped with bromine (Br).

[0065] The above negative electrode (111) may include lithium metal, and the lithium metal may be in the form of an alloy with some metal or with some component added to lithium. Since the negative electrode (111) includes lithium metal, it may be called a lithium metal layer.

[0066] The above double-sided positive electrode (113) may include a positive electrode active material layer (113b) on both sides of a positive electrode current collector (113a). The positive electrode active material layer (113b) includes a positive electrode active material, and may further include a solid electrolyte, a conductive material, a binder, and additives. The positive electrode current collector (113a), positive electrode active material, solid electrolyte, conductive material, binder, and additives are not particularly limited as long as they are generally used in the relevant technical field.

[0067] The above-mentioned positive electrode current collector (113a) supports the positive electrode active material layer (113b), and is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. For example, copper, stainless steel, aluminum, nickel, titanium, palladium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, silver, etc., aluminum-cadmium alloy, etc. can be used.

[0068] The above-mentioned positive electrode current collector (113a) can form fine irregularities on its surface to strengthen the bonding strength with the positive electrode active material, and can be used in various forms such as a film, sheet, foil, mesh, net, porous body, foam, and non-woven fabric.

[0069] The above positive electrode active material is a layered compound such as lithium cobalt oxide (LiCoO2), 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(0≤x≤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 lithium nickel oxide represented by O2 (M = Co, Mn, Al, Cu, Fe, Mg, B or Ga; 0.01≤x≤0.3); chemical formula LiMn 2-x M x Lithium manganese composite oxides expressed as O2 (M = Co, Ni, Fe, Cr, Zn or Ta; 0.01≤x≤0.1) or Li2Mn3MO8 (M = Fe, Co, Ni, Cu or Zn); LiNi x Mn 2-x Lithium manganese composite oxide with spinel structure represented by O4; LiCoPO4; LiFePO4; Elemental sulfur (S8); Li2S n(n=1), organosulfur compounds or carbon-sulfur polymers (C2S x ) n : It may include sulfur series compounds such as x=2.5 ~ 50, n=2), but is not limited to these.

[0070] The longitudinal length of the above solid electrolyte (112) may be the same as or longer than the longitudinal length of the cathode (111), but preferably may be longer than the longitudinal length of the cathode (111).

[0071] The longitudinal length of the above cathode (111) may be the same as or longer than the longitudinal length of the double-sided anode (113), but preferably may be longer than the longitudinal length of the double-sided anode (113).

[0072] Therefore, the longitudinal length may be long in the order of the solid electrolyte (112), the cathode (111), and the double-sided anode (113).

[0073] The above cathode (111) and solid electrolyte (112) may be formed as a cathode-solid electrolyte layer by coating the cathode (111) on the solid electrolyte (112) or transferring the cathode (111) on the solid electrolyte (112).

[0074] According to one embodiment of the present invention, the electrode laminate (110) may be manufactured by sequentially laminating a cathode (111), a solid electrolyte (112), a double-sided anode (113), a solid electrolyte (112), and a cathode (111), and then isotropically pressing the laminate.

[0075]

[0076] According to one embodiment of the present invention, an electrode assembly (100) can be manufactured by folding a negative electrode current collector structure (120) to alternately stack an electrode stack (110) and a negative electrode current collector structure (120). The negative electrode current collector structure (120) can be placed at the bottom and the electrode stack (110) can be sequentially stacked by placing the electrode stack (110) thereon. At this time, the folding can be performed so that the insulating layer (122) is positioned on the inner side of the folding portion (124) of the negative electrode current collector stack (120) in the direction of the electrode stack (110).

[0077] The outermost layer of the electrode assembly (100) according to one embodiment of the present invention may be where the negative electrode current collector structure (120) is positioned, and more specifically, the stack portion (123) of the negative electrode current collector structure (120), that is, the negative electrode current collector (121) may be positioned.

[0078]

[0079] An electrode assembly (100) according to one embodiment of the present invention is applied to an electrochemical device. The electrochemical device may include any device that undergoes an electrochemical reaction. For example, the electrochemical device may be any type of primary battery, secondary battery, fuel cell, solar cell, or capacitor. When the electrochemical device is a secondary battery, the electrochemical device may be a lithium secondary battery, and preferably, an all-solid-state battery.

[0080]

[0081] Although the specific examples described above have been limited to specific examples and drawings, those skilled in the art will recognize that various modifications and variations can be made based on the above teachings. For example, appropriate results can still be achieved even if the described techniques are performed in a different order than described, and / or components of the described systems, structures, devices, circuits, etc. are combined or combined in a different manner than described, or are replaced or substituted with other components or equivalents.

[0082]

[0083] [Explanation of symbols]

[0084] 100: Electrode assembly 110: Electrode stack

[0085] 111: Cathode 112: Solid electrolyte

[0086] 113: Double-sided positive electrode 113a: Positive current collector

[0087] 113b: Positive electrode active material layer 120: Negative electrode current collecting structure

[0088] 121: Negative current collector 122, 122a, 122b: Insulating layer

[0089] 123: Stack section 124: Folding section

Claims

1. An electrode assembly including a cathode current collector structure and a plurality of electrode stacks, The above electrode laminate has a structure in which a cathode, a solid electrolyte, a double-sided anode, a solid electrolyte, and a cathode are laminated in that order. The above negative electrode current collector structure includes a negative electrode current collector and a plurality of insulating layers laminated on the negative electrode current collector while being spaced apart from each other, and the portion where the insulating layers are laminated forms a folding portion, and the portion where the insulating layers are not laminated is bent in a zigzag manner to form a horizontal stack portion. An electrode assembly in which one electrode laminate is inserted and laminated between the adjacent stack portions and the stack portions, and an insulating layer is positioned on the inner side of the electrode laminate in the folding portion.

2. In paragraph 1, The spacing between the above multiple insulating layers is equal to the length of the stack portion, An electrode assembly, wherein the insulating layers are alternately positioned on one side and the other side of the negative electrode collector.

3. In paragraph 1, An electrode assembly wherein the length of the insulating layer is the same as the length of the folding portion.

4. In paragraph 1, An electrode assembly, wherein the stack portion is in close contact with the cathode of the electrode laminate.

5. In paragraph 1, An electrode assembly, wherein the above folding portion is in contact with a side surface of the electrode laminate.

6. In paragraph 1, An electrode assembly wherein the above negative electrode current collector is formed continuously.

7. In paragraph 1, An electrode assembly, wherein a plurality of stack sections and folding sections included in the above negative electrode current collector structure are alternately and continuously connected.

8. In paragraph 1, An electrode assembly in which the double-sided positive electrode includes a positive electrode active material layer on both sides of the positive electrode current collector.

9. In paragraph 1, An electrode assembly, wherein the cathode comprises lithium metal.

10. In paragraph 1, An electrode assembly wherein the above solid electrolyte is a sulfide-based solid electrolyte.

11. In paragraph 1, An electrode assembly wherein the length of the solid electrolyte is equal to or longer than the length of the cathode.

12. In paragraph 1, An electrode assembly wherein the length of the cathode is equal to or longer than the length of the double-sided anode.

13. An electrochemical device comprising an electrode assembly according to any one of claims 1 to 12.

14. In paragraph 13, The above electrochemical device is an all-solid-state battery.

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