Electrode assembly and electrochemical device

Abstract

To provide an electrode assembly capable of reducing the risk of a lithium deposition problem by solving a voltage shortage problem at a tab position, and an electrochemical device comprising the electrode assembly.SOLUTION: There is provided an electrode assembly including a cathode sheet 10, an anode sheet 20, a separator and a cathode tab 41. The cathode sheet includes a cathode collector 11 and a cathode active material layer 12 provided on the surface of the cathode collector. The anode sheet includes an anode collector 21 and an anode active material layer 22 provided on the surface of the anode collector. The separator is provided between the cathode sheet and the anode sheet. A first recessed groove 13 is provided in the cathode active material layer. One end of the cathode tab is provided in the first recessed groove and electrically connected with the cathode collector. A second recessed groove 23 is provided in the anode active material layer. The second recessed groove corresponds to the first recessed groove and extends to the anode collector in the thickness direction of the electrode assembly. A first protective rubber 50 is provided in the second recessed groove.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This application relates to the field of batteries, and particularly to an electrode assembly and an electrochemical device including this electrode assembly.

Background Art

[0002] Lithium-ion batteries are currently widely applied in convenient scenarios such as consumer electronics and power tools, and the application ratio of fast-charging battery cells in the market is increasing. In recent years, with the development of fast-charging battery cells, a battery cell structure with lower internal resistance has been demanded. In addition, a structure has been developed and applied in which a concave groove is formed in the middle of the electrode sheet and a tab is welded to the center of the electrode sheet. However, in this structure, there is a large local thickness difference at the position of the concave groove, the surface uniformity of the electrode sheet becomes poor, resulting in voltage deficiency in some regions during the formation process of the battery cell. As a result, in the later stage of battery cell recycling, lithium precipitation problems due to poor interfacial infiltration in the defective regions occur, and thermal runaway due to internal short circuit is likely to occur.

Summary of the Invention

[0003] In view of the above situation, this application provides an electrode assembly that can guarantee the thickness uniformity between the concave groove part and the main body region of the electrode sheet, improve the voltage deficiency problem at the tab position, and reduce the risk of lithium precipitation problems by filling the concave groove with a first protective rubber, and an electrochemical device including this electrode assembly.

[0004] The electrode assembly according to an embodiment of the present application includes a positive electrode sheet, a negative electrode sheet, a separator, and a positive electrode tab. The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer provided on the surface of the positive electrode current collector. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer provided on the surface of the negative electrode current collector. The separator is provided between the positive electrode sheet and the negative electrode sheet. The positive electrode tab is electrically connected to the positive electrode current collector. A first concave groove is provided in the positive electrode active material layer. One end of the positive electrode tab is provided in the first concave groove and is electrically connected to the positive electrode current collector. A second concave groove is provided in the negative electrode active material layer. The second concave groove corresponds to the first concave groove and extends to the negative electrode current collector along the thickness direction of the electrode assembly. A first protective rubber is provided in the second concave groove.

[0005] According to one aspect, along the thickness direction of the electrode assembly, the thickness of the first protective rubber is smaller than or equal to the depth of the second concave groove.

[0006] According to one aspect, the positive electrode sheet includes a first end and a second end provided opposite to each other, and in the direction extending from the first end to the second end, the width of the positive electrode tab is smaller than the width of the second concave groove.

[0007] According to one aspect, the peripheral portion of the first protective rubber is in contact with the negative electrode active material layer.

[0008] According to one aspect, the positive electrode sheet, the separator, and the negative electrode sheet are sequentially wound and installed.

[0009] According to one aspect, a first insulating member covering the first concave groove is provided on the positive electrode sheet.

[0010] According to one aspect, the first insulating member covers a part of the positive electrode active material layer.

[0011] According to one aspect, a second insulating member covering the second concave groove is provided on the negative electrode sheet.

[0012] According to one aspect, the second insulating member covers a part of the negative electrode active material layer.

[0013] According to one aspect, in the thickness direction of the electrode assembly, the projected area of the first insulating member is larger than the projected area of the second insulating member.

[0014] According to one aspect, a second protective rubber is provided in the first concave groove.

[0015] According to one aspect, the peripheral edge of the second protective rubber is in contact with the positive electrode active material layer.

[0016] According to one aspect, the first protective rubber is paper, a coated adhesive layer, or a filled adhesive.

[0017] According to one aspect, the width of the first protective rubber is W1, the width of the second concave groove is W2, the width of the second insulating member is W3, and the width of the first insulating member is W4, where W1 < W2 < W3 < W4.

[0018] According to one aspect, the length of the first protective rubber is L1, the length of the second concave groove is L2, the length of the second insulating member is L3, and the length of the first insulating member is L4, where L1 < L2 < L3 < L4.

[0019] According to one aspect, the thickness of the first protective rubber is T1 and the depth of the second concave groove is T2, where T1 ≤ T2.

[0020] According to one aspect, the dimensional relationship between the second concave groove and the first protective rubber satisfies 0 mm ≤ L2 - L1 ≤ 5 mm, 0 mm ≤ W2 - W1 ≤ 5 mm, and 0 μm ≤ T2 - T1 ≤ 20 μm.

[0021] According to one aspect, the dimensional relationship between the second concave groove and the first protective rubber satisfies 1 mm ≤ L2 - L1 ≤ 5 mm, 1 mm ≤ W2 - W1 ≤ 5 mm, and 0 μm ≤ T2 - T1 ≤ 20 μm.

[0022] According to one aspect, the dimensional relationship between the second concave groove and the second insulating member satisfies 1 mm ≤ L3 - L2 ≤ 5 mm and 1 mm ≤ W3 - W2 ≤ 5 mm.

[0023] According to one aspect, the dimensional relationship between the first insulating member and the second insulating member satisfies 1 mm ≤ L4 - L3 ≤ 10 mm and 1 mm ≤ W4 - W3 ≤ 10 mm.

[0024] According to one aspect, the dimensional relationship between the first insulating member and the second concave groove satisfies 1 mm ≤ L4 - L2 ≤ 10 mm and 1 mm ≤ W4 - W2 ≤ 10 mm.

[0025] According to one aspect, the dimensional relationship between the first protective rubber and the second concave groove satisfies W1 = W2 and L1 = L2.

[0026] According to one aspect, the width of the positive electrode tab is W0, and the length of the portion of the positive electrode tab located within the first concave groove is L0, where L0 < L1 = L2 and W0 < W1 = W2.

[0027] According to one aspect, the dimensional relationship between the first insulating member and the second concave groove satisfies 1 mm ≤ L4 - L2 ≤ 10 mm and 1 mm ≤ W4 - W2 ≤ 10 mm.

[0028] According to one aspect, the width of the second protective rubber is the same as the width W5 of the first concave groove, the length of the second protective rubber is the same as the length L5 of the first concave groove, and the dimensional relationship between the first concave groove and the second concave groove satisfies 1 mm ≤ L5 - L2 ≤ 10 mm and 1 mm ≤ W5 - W2 ≤ 10 mm.

[0029] The embodiment of the present application further provides an electrochemical device including a packaging case housed in the packaging case and the electrode assembly.

Advantages of the Invention

[0030] By filling the second concave groove with the first protective rubber, the thickness of the portion of the second concave groove and the main body region of the electrode sheet is ensured to be consistent, improving the problem of voltage shortage at the tab position and reducing the risk of lithium precipitation. Further, in the electrode assembly, the second concave groove corresponds to the first concave groove and extends to the negative electrode current collector along the thickness direction of the electrode assembly, leaving sufficient space for the welding burr of the positive electrode tab to prevent the welding burr from penetrating the second concave groove. Even when the welding burr penetrates the second concave groove, the positive electrode current collector electrically connected to the positive electrode tab contacts the negative electrode current collector instead of contacting the negative electrode active material layer, preventing the occurrence of the most dangerous short-circuit situation.

Brief Description of the Drawings

[0031]

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Mode for Carrying Out the Invention

[0032] Hereinafter, in relation to the drawings of the embodiments of the present application, the technical aspects of the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. When one component is referred to as being "fixed to" another component, it may be directly present in the other component or fixed via other elements. Also, when one component is referred to as being "connected to" another component, it may be directly connected to the other component or an intermediate medium may be present at the same time. Also, when one component is referred to as being "provided on" another component, it may be directly provided on the other component or an intermediate medium may be present at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used in the text are used only for the purpose of explanation.

[0033] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in this specification are for the purpose of describing specific embodiments only and are not meant to limit the present application. The term "or / and" used in this specification includes any and all combinations of one or more related items.

[0034] The electrode assembly according to the embodiment of the present application includes a positive electrode sheet, a negative electrode sheet, a separator, and a positive electrode tab. The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer provided on the surface of the positive electrode current collector. The negative electrode sheet is laminated and disposed with the positive electrode sheet, and includes a negative electrode current collector and a negative electrode active material layer provided on the surface of the negative electrode current collector. The separator is provided between the positive electrode sheet and the negative electrode sheet. The positive electrode tab is electrically connected to the positive electrode current collector. A first concave groove is provided in the positive electrode active material layer. One end of the positive electrode tab is provided in the first concave groove and is electrically connected to the positive electrode current collector. A second concave groove is provided in the negative electrode active material layer. The second concave groove corresponds to the first concave groove and extends to the negative electrode current collector along the thickness direction of the electrode assembly. A first protective rubber is provided in the second concave groove.

[0035] By filling the second concave groove with the first protective rubber in the above electrode assembly, it is ensured that the thickness of the part of the second concave groove and the main body region of the electrode sheet are the same, improving the problem of voltage shortage at the tab position and reducing the risk of lithium precipitation. The second concave groove corresponds to the first concave groove and extends to the negative electrode current collector along the thickness direction of the electrode assembly, leaving sufficient space for the welding burr of the positive electrode tab to prevent the welding burr from penetrating the second concave groove. Even if the welding burr penetrates the second concave groove, the positive electrode current collector electrically connected to the positive electrode tab contacts the negative electrode current collector instead of contacting the negative electrode active material layer, preventing the occurrence of the most dangerous short-circuit situation.

[0036] Some embodiments of the present application will be described in detail. If there is no conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0037] [First Embodiment] As shown in FIGS. 1, 2, and 3, the electrode assembly 100 includes a positive electrode sheet 10, a negative electrode sheet 20, a separator 30, a positive electrode tab 41, and a negative electrode tab 42. The positive electrode sheet 10 and the negative electrode sheet 20 are arranged to be stacked and wound. The separator 30 is provided between the positive electrode sheet 10 and the negative electrode sheet 20. The positive electrode tab 41 is electrically connected to the positive electrode sheet 10. The negative electrode tab 42 is electrically connected to the negative electrode sheet 20.

[0038] Specifically, as shown in FIG. 2, the positive electrode sheet 10 includes a positive electrode current collector 11 and a positive electrode active material layer 12 provided on the surface of the positive electrode current collector 11. In this embodiment, the positive electrode active material layers 12 are provided on the opposite surfaces of the positive electrode current collector 11, respectively. The positive electrode active material layer 12 is provided with a first concave groove 13 and a third concave groove 14, respectively. Along the thickness direction of the electrode assembly 100, that is, the direction indicated by arrow A in FIG. 2, the projections of the first concave groove 13 and the third concave groove 14 overlap. The portion of the positive electrode current collector 11 corresponding to the first concave groove 13 is exposed from the first concave groove 13 and the third concave groove 14. One end of the positive electrode tab 41 is provided in the first concave groove 13 and is electrically connected to the positive electrode current collector 11. The connection method between the positive electrode tab 41 and the positive electrode current collector 11 includes, but is not limited to, ultrasonic welding, hot melt welding, etc. The arrangement of the third concave groove 14 is advantageous for avoiding welding failure due to the contamination of the welding head and the welding holder by the positive electrode active material layer 12 during welding. On the other hand, when the thickness of the tab is greater than the depth of the first concave groove 13, the positive electrode current collector 11 in the first concave groove 13 can be recessed toward the third concave groove 14, whereby the third concave groove 14 can absorb the thickness of the positive electrode tab 41, and the protrusion of the positive electrode tab 41 from the surface of the positive electrode sheet 10 is avoided, and the overall thickness of the electrode assembly 100 is maintained uniformly. The negative electrode sheet 20 includes a negative electrode current collector 21 and a negative electrode active material layer 22 provided on the surface of the negative electrode current collector 21. In this embodiment, the negative electrode active material layers 22 are provided on the opposite surfaces of the negative electrode current collector 21, respectively. The negative electrode active material layer 22 is provided with a second concave groove 23 corresponding to the first concave groove 13 and a fourth concave groove 24 corresponding to the third concave groove 14, which are spaced apart. Further, the second concave groove 23 extends to the negative electrode current collector 21 along the thickness direction of the electrode assembly 100, and the fourth concave groove 24 extends to the negative electrode current collector 21 along the thickness direction of the electrode assembly 100, whereby it is possible to prevent an internal short circuit of the electrode assembly 100 due to the contact of the burrs caused by lithium precipitation in the second concave groove 23 and the fourth concave groove 24 with the tab. The thickness direction of the electrode assembly 100 is the direction indicated by arrow A in FIG. 2.The second concave groove 23 corresponds to the first concave groove 13, and the fourth concave groove 24 corresponds to the third concave groove 14. Moreover, the second concave groove 23 and the fourth concave groove 24 extend to the negative electrode current collector 21 along the thickness direction of the electrode assembly 100, leaving sufficient space for the welding burr of the positive electrode tab 41 to prevent the welding burr from penetrating the second concave groove 23. Even when the welding burr penetrates the second concave groove 23, the positive electrode current collector 11 electrically connected to the positive electrode tab 41 does not contact the negative electrode active material layer 22 but contacts the negative electrode current collector 21, preventing the occurrence of the most dangerous short-circuit situation. In the second concave groove 23 and the fourth concave groove 24, a first protective rubber 50 is further provided to solve the thickness difference generated after the active material is removed from the concave groove itself, ensure the thickness consistency between the concave groove portion and the main body region of the electrode sheet, further maintain the cycle performance consistency of the electrode assembly 100, and improve the kinetic performance of the electrode assembly 100. The first protective rubber 50 has insulation properties and only needs to be able to compensate for the thickness difference of the concave groove portion, including but not limited to adhesive tapes or other fluid filling adhesives.

[0039] Referring to FIG. 2 again, along the thickness direction of the electrode assembly 100, the thickness of the first protective rubber 50 is smaller than or equal to the depth of the second concave groove 23 and the fourth concave groove 24 in order to prevent the first protective rubber 50 from overflowing to the separator 30 after filling the concave groove and causing an increase in the thickness of a local area. As shown in FIG. 3, in the first embodiment, the first protective rubber 50 is located at the center of the corresponding concave groove, leaving a gap between its peripheral portion and the negative electrode active material layer 22 to solve the overflow problem during the filling of the first protective rubber 50. In other embodiments, the peripheral portion of the first protective rubber 50 can be in contact with the negative electrode active material layer 22, and the present application is not limited thereto.

[0040] Furthermore, the positive electrode sheet 10 includes a first end 101 and a second end 102 which are arranged opposite to each other. In the direction extending from the first end 101 to the second end 102, that is, the direction indicated by arrow B in FIG. 2, in order to avoid the positive electrode tab 41 accidentally contacting the negative electrode active material layer 22 at the edge of the second concave groove 23 and causing a short circuit, the width of the positive electrode tab 41 is smaller than the width of the second concave groove 23. Furthermore, in order to simplify the process of the electrode assembly 100, the widths of the first concave groove 13, the third concave groove 14, the second concave groove 23, and the fourth concave groove 24 are substantially the same. Of course, in other embodiments, the widths of the first concave groove 13, the third concave groove 14, the second concave groove 23, and the fourth concave groove 24 may be different from each other.

[0041] Referring to FIGS. 2 and 3 again, the electrode assembly 100 further includes a first insulating member 60 and a second insulating member 70. The first insulating member 60 is provided on the positive electrode sheet 10, and the second insulating member 70 is provided on the negative electrode sheet 20. The two first insulating members 60 respectively cover the first concave groove 13 and the third concave groove 14, and cover a part of the positive electrode active material layer 12. The two second insulating members 70 respectively cover the second concave groove 23 and the fourth concave groove 24, and cover a part of the negative electrode active material layer 22. When the dimensions of the positive electrode active material layer 12 and the negative electrode active material layer 22 are equal, the uncovered area of the negative electrode active material layer 22 is larger than the uncovered area of the positive electrode active material layer 12. In order to have sufficient lithium embedding positions on the negative electrode sheet 20 and reduce the occurrence of lithium precipitation problems, along the stacking direction of the positive electrode sheet 10 and the negative electrode sheet 20, the positive projection area of the first insulating member 60 is larger than the positive projection area of the second insulating member 70. Specifically, along the direction indicated by arrow A in FIG. 2, the width of the first insulating member 60 is larger than the width of the second insulating member 70.

[0042] By setting the thicknesses of the first insulating member 60 and the second insulating member 70 to be 10 μm - 20 μm, local thickness increase of the electrode assembly 100 is prevented. The first insulating member 60 is made of the same material as the second insulating member 70 and includes, but is not limited to, insulating materials such as adhesive tapes. In this embodiment, the first insulating member 60 and the second insulating member 70 are single-sided tapes each including a base material layer and an adhesive layer. Here, in order to provide a sufficient rigidity filling effect and reduce the thickness difference between the concave groove portion and the main body portion of the electrode sheet, the thickness of the base material layer accounts for 1 / 5 to 1 / 4 of the thickness of the adhesive tape.

[0043] In this embodiment, along the direction indicated by arrow B in FIG. 2, the width of the first protective rubber 50 is W1, the width of the second concave groove 23 is W2, the width of the second insulating member 70 is W3, and the width of the first insulating member 60 is W4. Here, W1 < W2 < W3 < W4.

[0044] The positive electrode sheet 10 has a first side 103 and a second side 104 that are arranged opposite to each other. The first end 101 and the second end 102 are connected to the first side 103 and the second side 104. In the direction extending from the first side 103 to the second side 104, that is, the direction indicated by arrow C in FIG. 3, the length of the first protective rubber 50 is L1, the length of the second concave groove 23 is L2, the length of the second insulating member 70 is L3, and the length of the first insulating member 60 is L4. Here, L1 < L2 < L3 < L4.

[0045] In the thickness direction of the electrode assembly 100, that is, along the direction indicated by arrow A in FIG. 2, the thickness of the first protective rubber is T1, and the depth of the second concave groove 23 is T2, provided that T1 ≤ T2. The size of the first concave groove 13 is the same as the size of the third concave groove 14. The size of the second concave groove 23 is the same as the size of the fourth concave groove 24.

[0046] Based on the needs of dimensional design, the dimensional relationship between the second concave groove 23 and the first protective rubber 50 satisfies 1 mm ≤ L2 - L1 ≤ 5 mm, 1 mm ≤ W2 - W1 ≤ 5 mm, and 0 μm ≤ T2 - T1 ≤ 20 μm. The thickness of the first protective rubber 50 can be adjusted according to the thickness after the actual negative electrode active material layer 22 is consolidated.

[0047] The dimensional relationship between the second concave groove 23 and the second insulating member 70 satisfies 1 mm ≤ L3 - L2 ≤ 5 mm and 1 mm ≤ W3 - W2 ≤ 5 mm.

[0048] The dimensional relationship between the first insulating member 60 and the second insulating member 70 satisfies 1 mm ≤ L4 - L3 ≤ 10 mm and 1 mm ≤ W4 - W3 ≤ 10 mm.

[0049] The negative electrode tab 42 is electrically connected to the negative electrode current collector 21. The negative electrode tab 42 is provided in the same way as the positive electrode tab 41 and can be adaptively corrected according to the polarity characteristics of the positive electrode sheet 10 and the negative electrode sheet 20, and will not be described further here.

[0050] 〔Second Embodiment〕 As shown in FIGS. 4, 5, and 6, the electrode assembly 200 according to the second embodiment is substantially the same as the electrode assembly 100 of the first embodiment, but is different in that a second insulating member 70 covering the second concave groove 23 and the fourth concave groove 24 is not provided on the negative electrode sheet 20 of the electrode assembly 200. By omitting the second insulating member 70, the size of the first insulating member 60 can be reduced, which contributes to the improvement of the energy density of the electrode assembly 200.

[0051] In the second embodiment, the dimensional relationship between the second concave groove 23 and the first protective rubber 50 is 1 mm ≤ L2 - L1 ≤ 5 mm, 1 mm ≤ W2 - W1 ≤ 5 mm, and 0 μm ≤ T2 - T1 ≤ 20 μm.

[0052] The dimensional relationship between the first insulating member 60 and the first concave groove 23 satisfies 1 mm ≤ L4 - L2 ≤ 10 mm and 1 mm ≤ W4 - W2 ≤ 10 mm.

[0053] 〔Third Embodiment〕 As shown in FIGS. 7, 8, and 9, the electrode assembly 300 according to the third embodiment is substantially the same as the electrode assembly 100 of the first embodiment. However, in the electrode assembly 300, in order to eliminate the gap between the first protective rubber 50 and the second concave groove 23 or the fourth concave groove 24, the first protective rubber 50 is filled in the second concave groove 23 and the fourth concave groove 24 with equal area, and the periphery of the first protective rubber 50 is in contact with the negative electrode active material layer 22. The first protective rubber 50 does not generate fluidity even after curing. Eliminating the gap in the concave groove is advantageous for preventing the active material from overflowing during the subsequent pressurization process of the electrode assembly 300, and improving the pressure resistance performance and service life of the electrode assembly 300.

[0054] Referring to FIGS. 8 and 9 again, the width of the first protective rubber 50 is W1, and the length of the first protective rubber 50 is L1. The width of the second concave groove 23 is W2, and the length of the second concave groove 23 is L2. Since the second concave groove 23 is filled with the first protective rubber 50 with equal area, the dimensional relationship between the first protective rubber 50 and the second concave groove 23 satisfies W1 = W2 and L1 = L2.

[0055] The width of the positive electrode tab 41 is W0, and the length of the positive electrode tab 41 located in the first concave groove 13 is L0. Here, L0 < L1 = L2 and W0 < W1 = W2. Since the portion of the positive electrode tab 41 located in the first concave groove 13 is completely covered by the first protective rubber 50, it is advantageous for reducing the possibility that the positive electrode tab 41 unintentionally contacts the negative electrode active material layer 22.

[0056] 〔Fourth Embodiment〕 As shown in FIGS. 10, 11, and 12, the electrode assembly 400 according to the fourth embodiment is substantially the same as the electrode assembly 300 of the third embodiment, but is different in that the second insulating member 70 covering the second concave groove 23 and the fourth concave groove 24 is not provided on the negative electrode sheet 20 of the electrode assembly 400.

[0057] In the fourth embodiment, the dimensional relationship between the second concave groove 23 and the first protective rubber 50 satisfies L2 = L1, W2 = W1, and 0 μm ≤ T2 - T1 ≤ 20 μm.

[0058] The dimensional relationship between the first insulating member 60 and the second concave groove 23 satisfies 1 mm ≤ L4 - L2 ≤ 10 mm and 1 mm ≤ W4 - W2 ≤ 10 mm.

[0059] 〔Fifth Embodiment〕 As shown in FIGS. 13, 14, and 15, the electrode assembly 500 according to the fifth embodiment is substantially the same as the electrode assembly 400 of the fourth embodiment, except that the first insulating member 60 is not provided in the electrode assembly 500 and the second protective rubber 80 is provided in the first concave groove 13 and the third concave groove 14. Due to the structure of the electrode assembly 500, the thickness space occupied by the first insulating member 60 and the second insulating member 70 can be saved, and the energy density of the electrode assembly 500 can be increased. In addition, the filling of the first protective rubber 50 and the second protective rubber 80 can perform an insulating function, guarantee the surface flatness of the electrode sheet, and reduce the thickness difference between the concave groove portion and the main body portion of the electrode sheet.

[0060] The second protective rubber 80 is filled in the first concave groove 13 and the third concave groove 14 with equal area, and the periphery of the second protective rubber 80 is in contact with the positive electrode active material layer 12. After the second protective rubber 80 is cured, it does not generate fluidity. Eliminating the gap in the concave groove is advantageous for avoiding the overflow of the active material during the subsequent pressurization process of the electrode assembly 500 and improving the pressure resistance performance and service life of the electrode assembly 500.

[0061] In this embodiment, to ensure that there is a sufficient lithium embedding position in the negative electrode sheet 20 and reduce the risk of lithium precipitation, along the stacking direction of the positive electrode sheet 10 and the negative electrode sheet 20, the projected area of the first concave groove 13 is larger than the projected area of the second concave groove 23. The dimensions of the first concave groove 13 are the same as the dimensions of the third concave groove 14. The dimensions of the second concave groove 23 are the same as the dimensions of the fourth concave groove 24.

[0062] Referring again to FIGS. 14 and 15, in the fifth embodiment, the width of the second protective rubber 80 is the same W5 as the width of the first concave groove 13. The length of the second protective rubber 80 is the same L5 as the length of the first concave groove 13. The first concave groove 13 has the same size as the third concave groove 14 and its depth is T3. The thickness of the second protective rubber 80 is T4. Here, 0 μm ≤ T4 - T3 ≤ 20 μm. The thickness of the second protective rubber 80 is smaller than or equal to the depth of the first concave groove 13 and the third concave groove 14.

[0063] The width of the positive electrode tab 41 is W0 and the length of the positive electrode tab 41 is L0. The width of the second concave groove 23 is W2 and the length of the second concave groove 23 is L2. Here, 1 mm ≤ L2 - L0 ≤ 5 mm and 1 mm ≤ W2 - W0 ≤ 5 mm.

[0064] The dimensional relationship between the first concave groove 13 and the second concave groove 23 satisfies 1 mm ≤ L5 - L2 ≤ 10 mm and 1 mm ≤ W5 - W2 ≤ 10 mm.

[0065] The embodiment of the present application further provides an electrochemical device including a packaging case (not shown) and the electrode assembly described in any one of the above embodiments or a combination of embodiments, and the electrode assembly is housed in the packaging case.

[0066] The above embodiments are only used to explain the technical aspects of the present application and do not limit the present invention. Although the present invention has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that any modifications or equivalent replacements made to the technical aspects of the present application do not deviate from the spirit and scope of the technical aspects of the present application.

Explanation of Reference Numerals

[0067] 100, 200, 300, 400, 500 Electrode Assembly 10 Positive Electrode Sheet 101 First End 102 Second End 103 First Side 104 Second Side 11 Positive Electrode Current Collector 12 Positive electrode active material layer 13 First concave groove 14 Third concave groove 20 Negative electrode sheet 21 Negative electrode current collector 22 Negative electrode active material layer 23 Second concave groove 24 Fourth concave groove 30 Separator 41 Positive electrode tab 42 Negative electrode tab 50 First protective rubber 60 First insulating member 70 Second insulating member 80 Second protective rubber

Claims

1. A positive electrode sheet including a positive electrode current collector and a positive electrode active material layer provided on the surface of the positive electrode current collector; A negative electrode sheet including a negative electrode current collector and a negative electrode active material layer provided on the surface of the negative electrode current collector; A separator provided between the positive electrode sheet and the negative electrode sheet; A positive electrode tab electrically connected to the positive electrode current collector, and an electrode assembly comprising: A first concave groove is provided in the positive electrode active material layer, and one end of the positive electrode tab is provided in the first concave groove and is electrically connected to the positive electrode current collector; A second concave groove is provided in the negative electrode active material layer, the second concave groove corresponds to the first concave groove, the second concave groove extends to the negative electrode current collector along the thickness direction of the electrode assembly, and a first protective rubber is provided inside the second concave groove; A first insulating member covering the first concave groove is provided on the positive electrode sheet; An electrode assembly, wherein the length of the positive electrode sheet in the longitudinal direction of the first insulating member is greater than the length of the positive electrode sheet in the longitudinal direction of the first protective rubber.

2. The electrode assembly according to claim 1, wherein along the thickness direction of the electrode assembly, the thickness of the first protective rubber is smaller than or equal to the depth of the second concave groove.

3. The positive electrode sheet includes a first end and a second end provided opposite to each other, and in the longitudinal direction of the positive electrode sheet extending from the first end to the second end, the width of the positive electrode tab is smaller than the width of the second concave groove. The electrode assembly according to claim 1, characterized in that.

4. The electrode assembly according to claim 1, wherein the peripheral edge of the first protective rubber is in contact with the negative electrode active material layer.

5. The electrode assembly according to claim 1, wherein the positive electrode sheet, the separator, and the negative electrode sheet are sequentially wound and installed.

6. The electrode assembly according to claim 1, wherein the first insulating member covers a part of the positive electrode active material layer.

7. The electrode assembly according to claim 1, wherein a second insulating member covering the second concave groove is provided on the negative electrode sheet.

8. The width of the second concave groove is W2, the width of the second insulating member is W3, the width of the first insulating member is W4, and the electrode assembly according to claim 7, characterized in that W2 < W3 < W4.

9. The electrode assembly according to claim 7, wherein the second insulating member covers a part of the negative electrode active material layer.

10. The electrode assembly according to claim 7, wherein, in the thickness direction of the electrode assembly, the projected area of the first insulating member is larger than the projected area of the second insulating member.

11. The electrode assembly according to claim 1, wherein a second protective rubber is provided in the first concave groove.

12. The electrode assembly according to claim 11, wherein a peripheral portion of the second protective rubber is in contact with the positive electrode active material layer.

13. An electrochemical device comprising a packaging case and the electrode assembly according to any one of claims 1 to 12, wherein the electrode assembly is housed in the packaging case.

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