Electrode assembly and secondary battery including the same

Abstract

The invention relates to an electrode assembly and a secondary battery including the same. An electrode assembly according to an embodiment of the present invention may include a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, in which an avoidance recess is formed in one of the positive electrode and the negative electrode, and the avoidance recess is formed to be recessed in a region overlapping an end of the other of the positive electrode and the negative electrode.

Description

Technical Field

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2022-0110314, filed on August 31, 2022, which is hereby incorporated by reference in its entirety. Technical Field

[0004] The present invention relates to an electrode assembly and a device including the same, and more particularly, to an electrode assembly capable of improving safety and a secondary battery including the same. Background Art

[0005] Recently, as the demand for portable electronic products such as laptops, camcorders, and mobile phones has rapidly increased, and the development of electric vehicles, energy storage batteries, robots, satellites, etc. is becoming regular, a lot of research has been conducted on secondary batteries used as driving power sources.

[0006] Rechargeable batteries are classified into coin-type batteries, cylindrical batteries, prismatic batteries, and pouch-type batteries according to the shape of the battery case. The electrode assembly installed inside the battery case is a chargeable and dischargeable power generation device having a structure in which electrodes and separators are stacked.

[0007] When the charge / discharge cycle of a secondary battery including an electrode assembly is repeated, stress caused by expansion and contraction of the electrode may accumulate in the electrode assembly. If the stress accumulation exceeds a certain limit, deformation of the electrode assembly may occur, resulting in reduced stability of the battery and defects in performance. Summary of the invention

[0008] Technical issues

[0009] Embodiments of the present invention provide an electrode assembly capable of improving stability and a secondary battery including the electrode assembly.

[0010] The objects of the present invention are not limited to the above contents, and other objects not described herein will be clearly understood by those skilled in the art from the following description.

[0011] Technical Solution

[0012] An electrode assembly according to an embodiment of the present invention may include: a positive electrode and a negative electrode; and a separator arranged between the positive electrode and the negative electrode, wherein an escape recess is defined in either the positive electrode or the negative electrode, and the escape recess is defined to be recessed in an area overlapping with the ends of the remaining electrodes of the positive electrode and the negative electrode.

[0013] An avoidance recess defined by recessing an area overlapping with the winding end of the positive electrode can be set in the negative electrode, and the avoidance recess can be recessed from the inner surface of the negative electrode toward the outer surface of the negative electrode, the inner surface of the negative electrode is set toward the winding center part of the electrode assembly, and the outer surface of the negative electrode is set toward the winding outer part of the electrode assembly.

[0014] The negative electrode may include: a first negative electrode active material layer, which is arranged to face the central portion of the winding; a second negative electrode active material layer, which is arranged to face the outer portion of the winding; and a negative electrode collector, which is arranged between the first negative electrode active material layer and the second negative electrode active material layer, wherein the avoidance recess may be defined in the first negative active material layer.

[0015] The escape recessed portion may be provided in the form of a groove surrounded by the first negative electrode active material layer and the negative electrode current collector.

[0016] The negative electrode may include: a first negative electrode active material layer, which is arranged to face the central part of the winding and has a multilayer structure including multiple active material layers; a second negative electrode active material layer, which is arranged to face the outer part of the winding; and a negative electrode collector, which is arranged between the first negative electrode active material layer and the second negative electrode active material layer, wherein the avoidance recess may be defined in at least one active material layer among the multiple active material layers.

[0017] A thickness of at least one of the plurality of active material layers may be smaller than a thickness of the second negative electrode active material layer.

[0018] The first negative active material layer may include a first active material layer and a second active material layer, and the escape recess may be defined in at least one of the first active material layer or the second active material layer.

[0019] The escape recess may be provided in the form of a groove surrounded by the first active material layer and the second active material layer.

[0020] The escape recessed portion may be provided in the form of a groove surrounded by the second active material layer provided on the negative electrode current collector and the second active material layer provided on the first active material layer.

[0021] The escape recessed portion may be provided in the form of a groove along the width direction of the negative electrode to overlap with the winding end portion of the positive electrode, and the escape recessed portion having the groove shape may extend parallel to the width direction of the negative electrode.

[0022] The escape recess may include: a first escape recess defined in the negative electrode disposed outside the winding end portion of the positive electrode; and a second escape recess defined in the negative electrode disposed inside the winding end portion of the positive electrode.

[0023] The first avoidance portion can be recessed from the inner surface of the negative electrode toward the outer surface of the negative electrode, the inner surface of the negative electrode is arranged toward the winding central part of the electrode assembly, the outer surface of the negative electrode is arranged toward the winding outer part of the electrode assembly, and the second avoidance recessed portion can be recessed from the outer surface of the negative electrode toward the inner surface of the negative electrode.

[0024] In the negative electrode, a region overlapping with the winding end portion of the positive electrode and a region not overlapping with the winding end portion of the positive electrode may have different thicknesses from each other.

[0025] In the negative electrode, the thickness of a region overlapping with the winding end portion of the positive electrode may be smaller than the thickness of a region not overlapping with the winding end portion of the positive electrode.

[0026] The negative electrode may include: a first negative electrode active material layer, which is arranged to face the central part of the winding of the electrode assembly; a second negative electrode active material layer, which is arranged to face the outer part of the winding of the electrode assembly; and a negative electrode collector, which is arranged between the first negative electrode active material layer and the second negative electrode active material layer, wherein the negative electrode can be set as the negative electrode collector in an area overlapping with the winding end end of the positive electrode, and in the area overlapping with the winding end end of the positive electrode, the negative electrode can be composed of at least one of the first negative electrode active material layer or the second negative electrode active material layer and the negative electrode collector.

[0027] A secondary battery according to an embodiment of the present invention may include the above-mentioned electrode assembly.

[0028] Beneficial Effects

[0029] According to an embodiment of the present invention, a relief recess may be defined in any one of the positive electrode and the negative electrode. The relief recess may be used to avoid contact between the end of the positive electrode and the negative electrode.

[0030] Therefore, the present invention can reduce the direct contact stress applied from the winding end of the positive electrode to the negative electrode to prevent the occurrence of cracks and disconnections of the negative electrode, thereby improving battery performance degradation and ensuring stability.

[0031] In addition, various effects directly or indirectly recognized by the present disclosure can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a perspective view of a secondary battery including an electrode assembly according to a first embodiment of the present invention.

[0033] Figure 2 It is illustrated in Figure 1 An exploded perspective view of the electrode assembly in the unfolded state before being wound.

[0034] Figure 3 is Figure 2 Detailed cross-sectional view of the winding end of the negative electrode and the winding end of the positive electrode after the electrode assembly is wound.

[0035] Figure 4a It is a diagram showing Figure 3 A three-dimensional diagram of a negative electrode in a state of being unfolded before being wound, and Figure 4b This diagram shows the Figure 4a A cross-sectional view of a state in which the negative electrode and the positive electrode are wound on region A.

[0036] Figure 5 is a detailed cross-sectional view of a winding end portion of a negative electrode and a winding end portion of a positive electrode after an electrode assembly is wound according to a second embodiment of the present invention.

[0037] Figure 6a It is a diagram showing Figure 5 A three-dimensional diagram of a negative electrode in a state of being unfolded before being wound, and Figure 6b This diagram shows the Figure 6a A cross-sectional view of a state in which the negative electrode and the positive electrode are wound on region B.

[0038] Figure 7 is a detailed cross-sectional view of a winding end portion of a negative electrode and a winding end portion of a positive electrode after an electrode assembly is wound according to a third embodiment of the present invention.

[0039] Figure 8 is a detailed cross-sectional view of a winding end portion of a negative electrode and a winding end portion of a positive electrode after an electrode assembly is wound according to a fourth embodiment of the present invention. DETAILED DESCRIPTION

[0040] Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. However, the present invention can be implemented in several different forms and is not limited or constrained by the following embodiments.

[0041] In order to explain the present invention clearly, the detailed description of the parts not related to the specification or the related known technology that may unnecessarily obscure the gist of the present invention has been omitted, and in this specification, the reference numerals are added to the components in each figure. In this case, the same or similar reference numerals are assigned to the same or similar elements throughout the specification.

[0042] In addition, the terms or words used in the present specification and claims should not be restrictively interpreted as ordinary meanings or dictionary-based meanings, but should be interpreted as meanings and concepts consistent with the scope of the present invention based on the principle that the inventor can appropriately define the concepts of the terms to best describe and interpret his or her invention.

[0043] Secondary battery including electrode assembly according to first embodiment

[0044] Figure 1 is a perspective view of a secondary battery including an electrode assembly according to a first embodiment of the present invention, and Figure 2 It is illustrated in Figure 1 An exploded perspective view of the electrode assembly in the unfolded state before being wound.

[0045] Reference Figure 1 to Figure 2 , a secondary battery 10 according to an embodiment of the present invention may include an electrode assembly 100 and a battery case 180 .

[0046] The electrode assembly 100 may be accommodated in a battery case 180. The battery case 180 may include a battery can 182 and a cap assembly 181.

[0047] The battery can 182 may include a receiving portion 183 in which the electrode assembly 100 is received. The electrolyte may be injected into the receiving portion 183 so that the electrode assembly 100 is completely immersed in the battery can 182. The upper portion of the battery can 182 may be opened to serve as an inflow channel for the electrode assembly 100. The battery can 182 may include metal. For example, the battery can 182 may include stainless steel.

[0048] Since the battery can 182 accommodates the electrode assembly 100, the battery can 182 may be provided in a shape corresponding to the shape of the electrode assembly 100. For example, the battery can 182 may be provided in a cylindrical shape so as to accommodate the electrode assembly 100 provided in a wound shape.

[0049] The cap assembly 181 may be mounted on the battery can 182 to cover the opened upper portion of the battery can 182 and be coupled to the battery can 182. The cap assembly 181 may be provided by sequentially stacking a safety belt, a current blocking element, a positive temperature coefficient (PTC) element, and a top cover. The top cover is located on and coupled to the uppermost portion of the cap assembly 181 to transmit the current generated in the secondary battery to the outside.

[0050] One of the battery can 182 and the cap assembly 181 may be electrically connected to the positive electrode tab 250 of the electrode assembly 100, and the other of the battery can 182 and the cap 181 may be electrically connected to the negative electrode tab 260 of the electrode assembly 100. For example, the cap assembly 181 may be electrically connected to the positive electrode tab 250 by a welding process, and the bottom surface of the battery can 182 may be electrically connected to the negative electrode tab 260 by a welding process. As another example, one of the battery can 182 and the cap assembly 181 may be electrically connected to the positive electrode tab 250 and the negative electrode tab 260.

[0051] The electrode assembly 100 may be a chargeable and dischargeable power generation element. The electrode assembly 100 has a structure in which the electrode 130 and the separator 160 are combined and alternately stacked. The electrode assembly 100 may be arranged in a shape in which the electrode 130 and the separator 160 are alternately combined to be wound. The electrode assembly 100 may have a structure in which the diameter is radially expanded in proportion to the number of winding rotations. Here, the electrode assembly 100 may be wound into a cylindrical shape wound around the winding central portion (or central axis) C. For example, the electrode 130 may include a positive electrode 110 and a negative electrode 120, and the separator 160 may include a first separator 140 and a second separator 150. The electrode assembly 100 may be an electrode assembly in the form of a winding, which is wound into a cylindrical shape by stacking the positive electrode 110, the first separator 140, the negative electrode 120 and the second separator 150 in sequence.

[0052] The positive electrode 110 may include a positive electrode collector 113, a first positive electrode active material layer 111 disposed on an inner surface (e.g., a surface facing the winding central portion C) of the positive electrode collector 113, and a second positive electrode active material 112 disposed on an outer surface (e.g., a surface facing the winding outer portion O) of the positive electrode collector 113. The positive electrode 110 may not have a positive electrode uncoated portion on the winding outer portion O. In the winding outer portion O, the positive electrode collector 113 may not protrude beyond the first positive electrode active material layer 111 and the second positive electrode active material layer 111.

[0053] For example, the positive electrode current collector 113 may be provided as a foil made of an aluminum material. At least one of the first positive electrode active material layer 111 or the second positive electrode active material layer may include, for example, lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron phosphate, or a compound containing at least one of these materials and a mixture thereof.

[0054] The negative electrode 120 may include a negative electrode collector 123, a first negative electrode active material layer 121 disposed on an inner surface 123a of the negative electrode collector 123 (e.g., a surface facing the winding central portion C), and a second negative electrode active material 122 disposed on an outer surface of the negative electrode collector 123 (e.g., a surface facing the winding outer portion O). The negative electrode 120 may be divided into a negative electrode coating portion 125 (or coating portion) and a negative electrode uncoated portion (or uncoated portion) according to the formation positions of the first negative electrode active material layer 121 and the second negative electrode active material layer 122. The negative electrode coating portion 125 may be a region on which the first negative electrode active material layer 121 and the second negative electrode active material layer 122 are disposed. The negative electrode uncoated portion 126 may be a region on which at least one of the first negative electrode active material layer 121 or the second negative electrode active material layer 122 is not disposed. At least one negative electrode tab 260 may be welded to the negative electrode collector 123 of the negative electrode uncoated portion 126 by a method such as welding.

[0055] The negative electrode current collector 123 may be, for example, provided as a foil made of a copper (Cu) or nickel (Ni) material. At least one of the first negative electrode active material layer 121 or the second negative electrode active material layer 122 may include, for example, synthetic graphite, lithium metal, lithium alloy, carbon, petroleum coke, activated carbon, graphite, silicon compound, tin compound, titanium compound or alloy thereof. At least one of the first negative electrode active material layer 121 or the second negative electrode active material layer 122 may include, for example, non-graphite-based SiO (silicon oxide) or SiC (silicon carbide).

[0056] Since the negative electrode 120 is provided to surround the positive electrode 110 when being wound, the negative electrode 120 may be provided longer than the positive electrode 110. In the winding outer portion O of the electrode assembly 100, the first negative electrode active material layer 121 provided on the inner surface 123a of the negative electrode collector 123 may face the positive electrode 110. On the other hand, the second negative electrode active material layer 122 provided on the outer surface 123b of the negative electrode collector 123 may not face the positive electrode 110. Therefore, on the winding outer portion O of the electrode assembly, the first negative electrode active material layer 121 may be provided longer than the second negative electrode active material layer 122. In the winding outer portion O of the electrode assembly, the end (e.g., winding end end) of the first negative electrode active material layer 121 may be provided closer to the end (e.g., winding end end) of the negative electrode collector 123 than the end (e.g., winding end end) of the second negative electrode active material layer 122.

[0057] The separator 160 may be disposed between the positive electrode 110 and the negative electrode 120 to separate and electrically insulate the positive electrode 110 from the negative electrode 120. The separator 160 may include a first separator 140 and a second separator 150. The first separator 140 may be stacked on the outer side of the positive electrode 110 or the negative electrode 120. The second separator 150 may be stacked on the outer side of the other of the positive electrode 110 and the negative electrode 120. For example, when the first separator 140 is stacked on the outer side of the positive electrode 110, the first separator 140 may be disposed between the second positive electrode active material layer 112 and the first negative electrode active material layer 121. When the second separator 150 is stacked on the outer side of the negative electrode 120, the second separator 150 may be disposed between the first positive electrode active material layer 111 and the second negative electrode active material layer 122. When a stack in which the positive electrode 110 , the first separator 140 , the negative electrode 120 , and the second separator 150 are sequentially stacked is wound, a wound type electrode assembly 110 in which the second separator 150 is disposed on the outermost surface may be provided.

[0058] At least one of the first separator 140 or the second separator 150 may be, for example, a multilayer film made of polyethylene, polypropylene or a combination thereof, or a polymer film for a solid polymer electrolyte or a gel-type polymer electrolyte such as polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile or polyvinylidene fluoride hexafluoropropylene copolymer.

[0059] In the electrode assembly 100 according to the present invention, a relief recess (or first relief recess) 200, which is an empty space, may be defined in at least one of the negative electrode 120 or the positive electrode 110. The relief recess 200 may be defined in the negative electrode 120 or the positive electrode 110. The relief recess 200 may be defined to be recessed in a region overlapping with the end of the other one of the negative electrode 120 and the positive electrode 110. For example, the relief recess 200 may be defined in a partial region of the negative electrode 120 corresponding to the winding end end of the positive electrode 110.

[0060] Figure 3 is Figure 2 A detailed cross-sectional view of the winding end end CE of the negative electrode and the winding end end AE of the positive electrode after the electrode assembly is wound, Figure 4a It is a diagram showing Figure 3 A three-dimensional diagram of a negative electrode in a state where it is unfolded before winding, and Figure 4b This diagram shows the Figure 4a A cross-sectional view of the state where the negative electrode and the positive electrode are wound on the region A. Figure 3, the wound positive electrode 110, the first separator 140, the negative electrode 120, and the second separator 150 are illustrated as being spaced apart from each other, but the wound positive electrode 110, the first separator 140, the negative electrode 120, and the second separator 150 may be in close contact with each other.

[0061] Reference Figures 3 to 4b , the negative electrode 120 may have different regions including a region overlapping with the winding end end AE of the positive electrode 110 and a region not overlapping with the winding end end AE of the positive electrode 110. In the negative electrode 120, the thickness of the region overlapping with the winding end end AE of the positive electrode 110 may be greater than the thickness of the region not overlapping with the winding end end AE of the positive electrode 110.

[0062] The negative electrode 120 may include at least one of the first negative electrode active material layer 121 or the second negative electrode active material layer 122 and the negative electrode current collector 123 in the region not overlapping with the winding end end AE of the positive electrode 110. The negative electrode 120 may have a maximum thickness corresponding to the thickness of the first negative electrode active material layer 121, the second negative electrode active material layer 122, and the negative electrode current collector 123 in the region not overlapping with at least part of the winding end AE of the positive electrode 110.

[0063] The negative electrode 120 may be provided as a negative electrode current collector 123 on a region overlapping with the winding end end AE of the positive electrode 110. The thickness of the negative electrode 120 may be less than the maximum thickness on a region overlapping with the winding end end AE of the positive electrode 110. The negative electrode 120 may have a thickness corresponding to the thickness of the negative electrode current collector 123 on a region overlapping with the winding end end AE of the positive electrode 110. An escape recess 200 overlapping with the winding end end AE of the positive electrode 110 may be defined in the negative electrode 120. The escape recess 200 may be recessed from the inner surface of the negative electrode 120 facing the winding central portion C to the outer surface of the negative electrode 120 facing the winding outer portion O. The escape recess 200 may be defined by recessing the first negative electrode active material layer 121 outward from the winding end end AE surface of the positive electrode 110. Since the first negative electrode active material layer 121 is not formed on the avoidance recess 200, the negative electrode current collector 123 may face the first separator 140 overlapping the avoidance recess 200. The avoidance recess 200 may be provided in the form of a groove surrounded by the first negative electrode active material layer 121 and the negative electrode current collector 123. A portion of the avoidance recess 200 may be open toward the first separator 140, and the remaining portion of the avoidance recess may be surrounded by the negative electrode current collector 123 and the first negative electrode active material layer 121. In the avoidance recess 200, the negative electrode current collector 123 may have a height difference relative to the first negative electrode active material layer 121.

[0064] like Figure 4aAs described, the escape recess 200 may be provided in a groove shape along the width direction of the negative electrode 120 to overlap the winding end of the positive electrode 110. The groove-shaped escape recess 200 may extend parallel to the width direction of the negative electrode 120.

[0065] The spacing distance between the winding end end AE of the positive electrode 110 and the negative electrode 120 may be increased by the avoidance recess 200. In the case of a comparative example in which the avoidance recess 200 is not formed, the winding end AE of the positive electrode 110 and the negative electrode 120 may be spaced apart from each other by a spacing distance S1 between the first negative electrode active material layer 121 and the winding end AE (e.g., the thickness of the first separator 140). On the other hand, in the case of an embodiment in which the avoidance recess 200 is formed, the winding end AE of the positive electrode 110 and the negative electrode 120 may be spaced apart from each other by a spacing distance S2 between the first current collector 123 and the winding end AE of the positive electrode 110 (e.g., the sum of the thickness of the first separator 140 and the thickness of the first negative electrode active material layer 121). Therefore, compared with the comparative example in which the avoidance recess 200 is not formed, in the embodiment in which the avoidance recess 200 is formed, the spacing distance between the winding end end AE of the positive electrode 110 and the negative electrode 120 can be further increased by the thickness of the first negative electrode active material layer 121.

[0066] The contact between the winding end portion AE of the positive electrode 110 and the negative electrode 120 can be avoided by avoiding the concave portion 200. Figure 4b As shown in FIG. 1 , direct contact between the winding end portion AE of the wound positive electrode 110 and the first negative electrode active material layer 121 can be avoided by avoiding the recessed portion 200. In the wound electrode assembly, the winding end portion AE of the positive electrode 110 and the negative electrode 120 may not contact each other. Therefore, the present invention can reduce the direct contact stress caused by the winding end portion AE of the positive electrode 110 to prevent cracks and disconnections of the negative electrode 120 from occurring.

[0067] Electrode assembly according to second embodiment

[0068] Figure 5 is a detailed cross-sectional view of a winding end portion of a negative electrode and a winding end portion of a positive electrode after an electrode assembly is wound according to a second embodiment of the present invention, Figure 6a It is a diagram showing Figure 5 A three-dimensional diagram of a negative electrode in a state of being unfolded before being wound, and Figure 6b This diagram shows the Figure 6a A cross-sectional view of the state where the negative electrode and the positive electrode are wound on the region B. Figure 5, the wound positive electrode 110, the first separator 140, the negative electrode 120, and the second separator 150 are illustrated as being spaced apart from each other, but the wound positive electrode 110, the first separator 140, the negative electrode 120, and the second separator 150 may be in close contact with each other.

[0069] Reference Figures 5 to 6b The electrode assembly according to the second embodiment of the present invention may include a negative electrode 120, a positive electrode 110, a first separator 140 and a second separator 150. The negative electrode 120 may include a first negative active material layer 121, a negative current collector 123 and a second negative active material layer 122.

[0070] The first negative active material layer 121 may be provided such that its inner surface faces the winding central portion C and its outer surface faces the winding outer portion O. The first negative active material layer 121 may be provided as a multilayer structure including a plurality of active material layers. The escape recess 200 may be defined in at least one active material layer among the plurality of active material layers.

[0071] For example, the first negative active material layer 121 may include a first active material layer 121a and a second active material layer 121b. The first active material layer 121a may be provided by being applied on the negative electrode current collector 123. The first active material layer 121a may be provided to have a first thickness d1 that is less than the thickness of the second positive active material layer 122. The first active material layer 121a may be made of the same or different material as the second active material layer 121b.

[0072] The second active material layer 121b may be provided by being applied on the first active material layer 121a, wherein the area of ​​the second active material layer 121b is greater than the area of ​​the first active material layer 121a. The second active material layer 121b may be provided to have a second thickness d2 that is less than the thickness of the second positive active material layer 122. The second thickness d2 may be the same as or different from the first thickness d1. The sum T1 of the first thickness d1 of the second active material layer 121a and the second thickness d2 of the first active material layer 121b may be the same as or similar to the thickness T2 of the second negative active material layer 122.

[0073] The relief recess 200 corresponding to the winding end AE of the positive electrode 110 may be defined in the first active material layer 121a or the second active material layer 121b. The relief recess 200 may be concavely defined to have an empty space in a region corresponding to the winding end AE of the positive electrode 110.

[0074] The escape recess 200 may be defined by recessing the first active material layer 121a facing the winding end portion AE of the positive electrode 110 toward the outside of the winding outer portion O. The first active material layer 121a may be disposed on at least a portion of the region other than the escape recess 200. The first active material layer 121a may not be disposed on the escape recess 200. A portion of the second active material layer 121b may be disposed on the negative electrode current collector 123 corresponding to the escape recess 200. At least the remaining portion of the second active material layer 121b may be disposed on the first active material layer 121a. The second active material layer 121b may face the first separator 140 overlapping the escape recess 200. The escape recess 200 may be provided in the form of a groove surrounded by the second active material layer 121b disposed on the negative electrode current collector 123 and the first active material layer 121a disposed on the first active material layer 121a. A portion of the relief recess 200 may be open toward the first separator 140, and the rest of the relief recess 200 may be surrounded by the second active material layer 121b. The second active material layer 121b disposed at the relief recess 200 may have a height difference relative to the second active material layer 121b disposed on the first active material layer 121a.

[0075] The spacing distance between the winding end end AE of the positive electrode 110 and the negative electrode 120 may be increased by the avoidance recess 200. In the case of a comparative example in which the avoidance recess 200 is not formed, the winding end end AE of the positive electrode 110 and the negative electrode 120 may be spaced apart from each other by a spacing distance S1 between the first negative electrode active material layer 121 and the winding end end AE (e.g., the minimum thickness of the first separator 140). On the other hand, in the case of an embodiment in which the avoidance recess 200 is formed, the winding end end AE of the positive electrode 110 and the negative electrode 120 may be spaced apart from each other by a spacing distance S2 between the first active material layer 121a or the second active material layer 121b and the winding end end AE of the positive electrode 110 (e.g., the sum of the thickness of the first active material layer 121a or the second active material layer 121b and the thickness of the first separator 140). Therefore, in an embodiment in which the avoidance recess 200 is formed, the spacing distance between the winding end end portion AE of the positive electrode 110 and the negative electrode 120 can be further increased by the thickness of the first negative electrode active material layer 121a or the second active material layer 121b compared to the comparative example in which the avoidance recess 200 is not formed.

[0076] The contact between the winding end AE of the positive electrode 110 and the negative electrode 120 can be avoided by the avoidance concave portion 200, and the avoidance concave portion 200 increases the spacing distance between the winding end AE of the positive electrode 110 and the negative electrode 120. Figure 6bAs shown in FIG. 2 , in the wound electrode assembly, the direct contact between the winding end portion AE of the positive electrode 110 and the first negative electrode active material layer 121 can be avoided by avoiding the recessed portion 200. In the wound electrode assembly, the winding end portion AE of the positive electrode 110 and the negative electrode 120 may not contact each other. Therefore, the present invention can reduce the direct contact stress caused by the winding end portion AE of the positive electrode 110 to prevent the occurrence of cracks and disconnections of the negative electrode 120 due to the contact stress.

[0077] In addition, the second active material layer 121b and the negative electrode current collector 123 may be disposed on a region overlapping the winding end end AE of the positive electrode 110. The positive electrode 120 may stably supply an electrical signal (e.g., current) through the negative electrode current collector 123 and the second negative electrode active material layer 121b located on a region overlapping the winding end end AE of the positive electrode 110.

[0078] Electrode assembly according to third embodiment

[0079] Figure 7 Detailed cross-sectional view of a winding end portion of a negative electrode and a winding end portion of a positive electrode after an electrode assembly is wound according to a third embodiment of the present invention. Figure 7 , the wound positive electrode 110, the first separator 140, the negative electrode 120, and the second separator 150 are illustrated as being spaced apart from each other, but the wound positive electrode 110, the first separator 140, the negative electrode 120, and the second separator 150 may be in close contact with each other.

[0080] Reference Figure 7 In addition to defining the avoidance recess 200 in the second active material layer 121b, the electrode assembly according to the third embodiment of the present invention may be provided with Figures 5 to 6b The electrode assembly shown in the figure has the same components. Therefore, detailed description of the same components will be omitted.

[0081] like Figure 7As illustrated in FIG. 1 , the escape recess 200 may be defined by recessing the second active material layer 121b facing the winding end end AE of the positive electrode 110 toward the outside of the winding outer portion O. The first active material layer 121a may be provided on the negative electrode current collector 123, wherein the area of ​​the first active material layer 121a is greater than the area of ​​the second active material layer 121b. The second active material layer 121b may be provided on an area of ​​the first active material layer 121a other than an area corresponding to the escape recess 200. The second active material layer 121b may face the first separator 140 overlapping the escape recess 200. The escape recess 200 may be provided in the form of a groove surrounded by the first active material layer 121a and the second active material layer 121b. A portion of the escape recess 200 may be open toward the first separator 140, and the remaining portion of the escape recess 200 may be surrounded by the first active material layer 121a and the second active material layer 121b. The first active material layer 121 a disposed at the escape recess 200 may have a height difference with respect to the second active material layer 121 b disposed on the first active material layer 121 a .

[0082] The contact between the winding end end AE of the positive electrode and the negative electrode 120 can be avoided by avoiding the concave portion 200. That is, in the wound electrode assembly, the direct contact between the winding end end AE of the positive electrode 110 and the first negative electrode active material layer 121 can be avoided by avoiding the concave portion 200. In the wound electrode assembly, the winding end end AE of the positive electrode 110 and the negative electrode 120 may not contact each other. Therefore, the present invention can reduce the direct contact stress caused by the winding end end AE of the positive electrode 110 to prevent cracks and disconnections of the negative electrode 120 from occurring.

[0083] Electrode assembly according to fourth embodiment

[0084] Figure 8 Detailed cross-sectional view of a winding end portion of a negative electrode and a winding end portion of a positive electrode after an electrode assembly is wound according to a fourth embodiment of the present invention. Figure 8 , the wound positive electrode 110, the first separator 140, the negative electrode 120, and the second separator 150 are illustrated as being spaced apart from each other, but the wound positive electrode 110, the first separator 140, the negative electrode 120, and the second separator 150 may be in close contact with each other.

[0085] Reference Figure 8 In addition to the electrode assembly further including the second avoidance recess 300, the electrode assembly according to the fourth embodiment of the present invention may be provided with Figures 3 to 4b . Therefore, detailed description of the same parts will be omitted.

[0086] The first escape recess 200 and the second escape recess 300 may be defined in the negative electrode 120. The first escape recess 200 may be defined in the negative electrode 120 disposed outside the winding end portion AE of the positive electrode 110. The first escape recess 200 may be recessed from the inner surface of the negative electrode 120 facing the winding center portion C toward the outer surface of the negative electrode 120 facing the winding outer portion O. For example, the first escape recess 200 may be recessed from the inner surface of the first negative electrode active material layer 121 disposed toward the winding center portion C toward the negative electrode current collector 123 disposed toward the winding outer portion O. The first escape recess 200 may be provided by recessing the first negative electrode active material layer 121 toward the negative electrode current collector 123. Contact between the second positive electrode active material layer 112 defining at least a portion of the outer side of the winding end portion AE of the positive electrode 110 and the negative electrode 120 may be avoided by the first escape recess 200. That is, in the wound electrode assembly, direct contact between the outer side of the winding end portion AE of the positive electrode 110 and the negative electrode 120 may be avoided by the first avoidance recessed portion 200 .

[0087] The second escape recess 300 may be defined in the negative electrode 120 disposed inside the winding end portion AE of the positive electrode 110. The second escape recess 300 may be recessed from the outer surface of the negative electrode 120 facing the winding outer portion O to the inner surface of the negative electrode 120 facing the winding central portion C. The second escape recess 300 may be recessed from the outer surface of the second negative electrode active material layer 122 facing the winding outer portion O to the inner surface of the first negative electrode active material layer 121 facing the winding central portion C. The second escape recess 300 may be provided by recessing the second negative electrode active material layer 122 toward the negative electrode current collector 123. Contact between the first positive electrode active material layer 111 defining at least a portion of the inner side of the winding end portion AE of the positive electrode 110 and the negative electrode 120 may be avoided by the second escape recess 300. That is, in the wound electrode assembly, direct contact between the inner side of the winding end portion AE of the positive electrode 110 and the negative electrode 120 may be avoided by the second avoidance recessed portion 300 .

[0088] As described above, in the wound electrode assembly, each of the inner and outer sides of the winding end portion AE of the positive electrode 110 and the negative electrode 120 may not contact each other. Therefore, the present invention can reduce the direct contact stress applied to the negative electrode 120 by the winding end portion AE of the positive electrode 110 to prevent cracks and disconnections of the negative electrode 120 caused by the direct contact stress.

[0089] The above-mentioned electrode assembly is not limited to the embodiment described in each figure, and the structure described in each figure can be applied in combination. In the secondary battery according to the present invention, only Figure 3The multiple electrode assemblies described in the Figure 5 The multiple electrode assemblies described in the Figure 7 The multiple electrode assemblies described in the Figure 8 The multiple electrode assemblies described in the above may be used in combination Figure 3 , Figure 5 , Figure 7 and Figure 8 Any one of the electrode assemblies described in and at least one of the electrode assemblies described in the remaining figures. The avoidance recess according to the present invention can also be provided not only in the winding outer part, but also in the winding middle part and the winding central part located between the winding central part and the winding outer part. The avoidance recess according to the present invention can be used for the negative electrode, the positive electrode, or a combination of the positive electrode and the negative electrode. As an example, the electrode assembly according to the present invention has been described as a structure applied to a cylindrical secondary battery, but this is not limited to this, and the electrode assembly can also be applied to a pouch-type battery or a prismatic battery.

[0090] The secondary battery including the electrode assembly described above can be applied to various devices. The secondary battery including the electrode assembly described above can be applied to vehicles such as electric bicycles, electric vehicles, hybrid vehicles, etc., but is not limited thereto, and can be applied to various devices that can use battery modules.

[0091] While embodiments of the present invention have been described with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

[0092] [Description of Reference Signs]

[0093] 100: Electrode assembly

[0094] 110: Positive

[0095] 120: Negative electrode

[0096] 140: First separator

[0097] 150: Second separator

[0098] 200: Avoid recessed areas

Claims

1. An electrode assembly, comprising: positive and negative electrodes; and a separator, the separator being disposed between the positive electrode and the negative electrode, wherein a relief recess is defined in any one of the positive electrode and the negative electrode, and The escape recessed portion is defined to be recessed in a region overlapping with ends of the remaining electrodes of the positive electrode and the negative electrode.

2. The electrode assembly according to claim 1, wherein: The escape recessed portion defined by recessing a region overlapping with the winding end portion of the positive electrode is provided in the negative electrode, and The avoidance recess is recessed from the inner surface of the negative electrode toward the outer surface of the negative electrode, the inner surface of the negative electrode is arranged toward the winding central part of the electrode assembly, and the outer surface of the negative electrode is arranged toward the winding outer part of the electrode assembly.

3. The electrode assembly according to claim 2, wherein: The negative electrode comprises: a first negative electrode active material layer, the first negative electrode active material layer being disposed facing the winding central portion; a second negative electrode active material layer disposed to face the wound outer portion; and a negative electrode current collector disposed between the first negative electrode active material layer and the second negative electrode active material layer, Wherein, the avoidance recess is defined in the first negative active material layer.

4. The electrode assembly according to claim 3, wherein: The escape recess is provided in the form of a groove surrounded by the first negative electrode active material layer and the negative electrode current collector.

5. The electrode assembly according to claim 2, wherein: The negative electrode comprises: a first negative electrode active material layer disposed to face the winding central portion and having a multilayer structure including a plurality of active material layers; a second negative electrode active material layer disposed to face the wound outer portion; and a negative electrode current collector disposed between the first negative electrode active material layer and the second negative electrode active material layer, The avoidance recess is defined in at least one active material layer among the plurality of active material layers.

6. The electrode assembly according to claim 5, wherein: A thickness of at least one of the plurality of active material layers is smaller than a thickness of the second negative electrode active material layer.

7. The electrode assembly according to claim 5, wherein: The first negative electrode active material layer includes a first active material layer and a second active material layer, and The escape recess is defined in at least one of the first active material layer or the second active material layer.

8. The electrode assembly according to claim 7, wherein: The escape recess is provided in the form of a groove surrounded by the first active material layer and the second active material layer.

9. The electrode assembly according to claim 7, wherein: The escape recessed portion is provided in the form of a groove surrounded by the second active material layer provided on the negative electrode current collector and the second active material layer provided on the first active material layer.

10. The electrode assembly according to claim 1, wherein: The avoidance recess is provided in the form of a groove along the width direction of the negative electrode so as to overlap with the winding end of the positive electrode, and The escape recessed portion having a groove shape extends parallel to a width direction of the negative electrode.

11. The electrode assembly according to claim 1, wherein: The avoidance recessed portion comprises: a first escape recessed portion defined in the negative electrode disposed outside a winding end portion of the positive electrode; and A second escape recessed portion is defined in the negative electrode disposed on the inner side of the winding finishing end portion of the positive electrode.

12. The electrode assembly according to claim 11, wherein: The first avoidance portion is recessed from the inner surface of the negative electrode toward the outer surface of the negative electrode, the inner surface of the negative electrode is arranged toward the winding center portion of the electrode assembly, and the outer surface of the negative electrode is arranged toward the winding outer portion of the electrode assembly, and The second escape recessed portion is recessed from the outer surface of the negative electrode toward the inner surface of the negative electrode.

13. The electrode assembly according to claim 1, wherein: In the negative electrode, a region overlapping with a winding end portion of the positive electrode and a region not overlapping with the winding end portion of the positive electrode have different thicknesses from each other.

14. The electrode assembly according to claim 13, wherein: In the negative electrode, a thickness of a region overlapping with a winding end portion of the positive electrode is smaller than a thickness of a region not overlapping with the winding end portion of the positive electrode.

15. The electrode assembly according to claim 13, wherein: The negative electrode comprises: a first negative electrode active material layer disposed to face a winding center portion of the electrode assembly; a second negative electrode active material layer disposed to face a wound outer portion of the electrode assembly; and a negative electrode current collector disposed between the first negative electrode active material layer and the second negative electrode active material layer, wherein the negative electrode is provided as the negative electrode collector in a region overlapping with the winding end portion of the positive electrode, and The negative electrode is composed of at least one of the first negative electrode active material layer or the second negative electrode active material layer and the negative electrode current collector in a region overlapping with the winding end portion of the positive electrode. 16 . A secondary battery comprising the electrode assembly according to claim 1 .

Images