Electrode assembly and electrochemical device

Abstract

The present application provides an electrode assembly including 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 disposed on the positive electrode current collector. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector. A separator is disposed between the positive electrode sheet and the negative electrode sheet. The positive electrode active material layer is provided with a first groove. One end of the positive electrode tab is disposed in the first groove and electrically connected to the positive electrode current collector. The negative electrode active material layer is provided with a second groove. The second groove corresponds to the first groove and extends to the negative electrode current collector along the thickness direction of the electrode assembly. A first protective rubber is disposed in the second groove. This ensures consistency in thickness between the groove portion and the main body region of the electrode sheet, thereby improving voltage insufficiency at the tab position and reducing the risk of short circuits. The present application also provides an electrochemical device including the above electrode assembly.

Description

[Technical field]

[0001] The present application relates to the field of batteries, and in particular to an electrode assembly and an electrochemical device comprising the electrode assembly. [Background technology]

[0002] Lithium-ion batteries are now widely used in consumer electronics, power tools and other convenient applications, and the application rate of fast-charging battery cells in the market is becoming higher and higher. In recent years, with the development of fast-charging battery cells, a battery cell structure with lower internal resistance is required. In addition, a structure in which a groove is drilled in the middle of the electrode sheet and a tab is welded to the center of the electrode sheet has been developed and applied. However, in this structure, there is a large thickness difference locally at the position of the groove, which leads to poor conformity of the surface of the electrode sheet, resulting in voltage deficiency in some areas during the chemical formation process of the battery cell. This causes lithium precipitation problems due to poor interfacial infiltration in the defective area in the later stage of battery cell recycling, and is prone to thermal runaway due to internal short circuit. Summary of the Invention

[0003] In view of the above situation, the present application provides an electrode assembly and an electrochemical device including the electrode assembly, which can ensure consistency in thickness between the groove area and the main body area of ​​the electrode sheet by filling the groove with a first protective rubber, thereby improving the voltage deficiency problem at the tab position and reducing the risk of lithium precipitation problems.

[0004] 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 collector and a positive electrode active material layer provided on the surface of the positive electrode collector. The negative electrode sheet includes a negative electrode collector and a negative electrode active material layer provided on the surface of the negative electrode 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 collector. The positive electrode active material layer is provided with a first groove. One end of the positive electrode tab is provided in the first groove and is electrically connected to the positive electrode collector. The negative electrode active material layer is provided with a second groove. The second groove corresponds to the first groove and extends to the negative electrode collector along the thickness direction of the electrode assembly. A first protective rubber is provided in the second groove.

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

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

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

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

[0009] According to one embodiment, the positive electrode sheet is provided with a first insulating member that covers the first groove.

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

[0011] According to one embodiment, the negative electrode sheet is provided with a second insulating member that covers the second groove.

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

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

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

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

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

[0017] According to one embodiment, the width of the first protective rubber is W1, the width of the second 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である。

[0018] According to one embodiment, the length of the first protective rubber is L1, the length of the second 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である。

[0019] According to one embodiment, the thickness of the first protective rubber is T1, the depth of the second groove is T2, and T1≦T2.

[0020] According to one embodiment, the dimensional relationships between the second groove and the first protective rubber satisfy 0 mm≦L2-L1≦5 mm, 0 mm≦W2-W1≦5 mm, and 0 μm≦T2-T1≦20 μm.

[0021] According to one embodiment, the dimensional relationships between the second groove and the first protective rubber satisfy 1 mm≦L2-L1≦5 mm, 1 mm≦W2-W1≦5 mm, and 0 μm≦T2-T1≦20 μm.

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

[0023] According to one embodiment, 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 embodiment, the dimensional relationship between the first insulating member and the second recessed groove satisfies 1 mm≦L4-L2≦10 mm and 1 mm≦W4-W2≦10 mm.

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

[0026] According to one embodiment, the width of the positive electrode tab is W0, and the length of the portion of the positive electrode tab located in the first groove is L0, where L0 <L1=L2、W0<W1=W2。

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

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

[0029] An embodiment of the present application further provides an electrochemical device including a packaging case contained in the packaging case and the electrode assembly. Effect of the Invention

[0030] In the above electrode assembly, the second groove is filled with the first protective rubber to ensure that the thickness of the second groove is consistent with that of the main body of the electrode sheet, thereby improving the voltage shortage problem at the tab position and reducing the risk of lithium precipitation. In addition, in the electrode assembly, the second groove corresponds to the first groove and extends to the negative electrode current collector along the thickness direction of the electrode assembly, leaving a sufficient space for the welding burr of the positive electrode tab and preventing the welding burr from penetrating the second groove. Even if the welding burr penetrates the second groove, the positive electrode current collector electrically connected to the positive electrode tab will contact the negative electrode current collector instead of the negative electrode active material layer, preventing the most dangerous short circuit situation from occurring. [Brief description of the drawings]

[0031] [Figure 1] FIG. 2 is a diagram showing a winding structure of the electrode assembly according to the first embodiment. [Diagram 2] FIG. 2 is a schematic diagram of the local structure of the electrode assembly shown in FIG. 1 after the separator is omitted. [Diagram 3] 2 is a schematic diagram showing the developed structure of the positive electrode sheet and the negative electrode sheet in the electrode assembly shown in FIG. 1. [Figure 4] FIG. 11 is a diagram showing a winding structure of an electrode assembly according to a second embodiment. [Diagram 5] FIG. 5 is a schematic diagram of the local structure of the electrode assembly shown in FIG. 4 after the separator is omitted. [Figure 6] 5 is a schematic diagram showing the developed structure of the positive electrode sheet and the negative electrode sheet in the electrode assembly shown in FIG. 4. [Figure 7] FIG. 13 is a diagram showing a winding structure of an electrode assembly according to a third embodiment. [Figure 8] FIG. 8 is a schematic diagram of the local structure of the electrode assembly shown in FIG. 7 after the separator is omitted. [Figure 9] 8 is a schematic diagram of an expanded structure of a positive electrode sheet and a negative electrode sheet in the electrode assembly shown in FIG. 7. FIG. [Figure 10] FIG. 13 is a diagram showing a winding structure of an electrode assembly according to a fourth embodiment. [Figure 11]FIG. 11 is a schematic diagram of the local structure of the electrode assembly shown in FIG. 10 after the separator is omitted. [Figure 12] 11 is a schematic diagram of an expanded structure of a positive electrode sheet and a negative electrode sheet in the electrode assembly shown in FIG. 10. FIG. [Figure 13] FIG. 13 is a diagram showing a winding structure of an electrode assembly according to a fifth embodiment. [Figure 14] FIG. 14 is a schematic diagram of the local structure of the electrode assembly shown in FIG. 13 after the separator has been omitted. [Figure 15] FIG. 14 is a schematic diagram of an expanded structure of the positive electrode sheet and the negative electrode sheet in the electrode assembly shown in FIG. 13. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Hereinafter, the technical aspects of the embodiments of the present application will be clearly and completely described in conjunction with the drawings of the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. When a part is said to be "fixed" to another part, it may be directly present in the other part, or it may be fixed via another element. When a part is said to be "connected" to another part, it may be directly connected to the other part, or there may be an intermediate medium at the same time. When a part is said to be "mounted" to another part, it may be directly mounted to the other part, or there may be an intermediate medium at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used in the present specification are used for explanatory purposes only.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art of this application. The terms used herein are only for describing specific embodiments and are not meant to be limiting of the present application. The term "or" used herein includes any and all combinations of one or more associated 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 collector and a positive electrode active material layer provided on the surface of the positive electrode collector. The negative electrode sheet is arranged by being laminated with the positive electrode sheet, and includes a negative electrode collector and a negative electrode active material layer provided on the surface of the negative electrode 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 collector. The positive electrode active material layer is provided with a first groove. One end of the positive electrode tab is provided in the first groove and is electrically connected to the positive electrode collector. The negative electrode active material layer is provided with a second groove. The second groove corresponds to the first groove and extends to the negative electrode collector along the thickness direction of the electrode assembly. A first protective rubber is provided in the second groove.

[0035] The electrode assembly fills the second groove with the first protective rubber to ensure that the thickness of the second groove is consistent with that of the main body of the electrode sheet, improving the voltage shortage problem at the tab position and reducing the risk of lithium precipitation. The second groove corresponds to the first groove and extends to the negative electrode current collector along the thickness direction of the electrode assembly, leaving enough space for the welding burr of the positive electrode tab and preventing the welding burr from penetrating the second groove. Even if the welding burr penetrates the second groove, the positive electrode current collector electrically connected to the positive electrode tab will contact the negative electrode current collector instead of the negative electrode active material layer, preventing the most dangerous short circuit situation from occurring.

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

[0037] [First embodiment] 1, 2 and 3, an 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 collector 11 and a positive electrode active material layer 12 provided on the surface of the positive electrode collector 11. In this embodiment, the positive electrode active material layer 12 is provided on each of the opposing surfaces of the positive electrode collector 11. The positive electrode active material layer 12 is provided with a first groove 13 and a third groove 14. Projections of the first groove 13 and the third groove 14 overlap along the thickness direction of the electrode assembly 100, i.e., the direction indicated by the arrow A in FIG. 2. A portion of the positive electrode collector 11 corresponding to the first groove 13 is exposed from the first groove 13 and the third groove 14. One end of the positive electrode tab 41 is provided in the first groove 13 and is electrically connected to the positive electrode collector 11. The method of connecting the positive electrode tab 41 and the positive electrode collector 11 includes, but is not limited to, ultrasonic welding, hot melt welding, and the like. The arrangement of the third groove 14 is advantageous in avoiding welding failures caused by contamination of the welding head and the welding holder by the positive electrode active material layer 12 during welding, while when the thickness of the tab is greater than the depth of the first groove 13, the positive electrode current collector 11 in the first groove 13 can be recessed toward the third groove 14, so that the third groove 14 can absorb the thickness of the positive electrode tab 41, and the positive electrode tab 41 is prevented from protruding from the surface of the positive electrode sheet 10, and the overall thickness of the electrode assembly 100 is maintained uniform. 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 layer 22 is provided on both opposing surfaces of the negative electrode current collector 21, respectively. The negative electrode active material layer 22 is provided with a second groove 23 corresponding to the first groove 13 and a fourth groove 24 corresponding to the third groove 14, which are spaced apart from each other. The second groove 23 extends to the negative electrode current collector 21 along the thickness direction of the electrode assembly 100, and the fourth groove 24 extends to the negative electrode current collector 21 along the thickness direction of the electrode assembly 100, thereby preventing an internal short circuit of the electrode assembly 100 caused by a burr due to lithium deposition in the second groove 23 and the fourth groove 24 coming into contact with a tab. The thickness direction of the electrode assembly 100 is the direction indicated by the arrow A in FIG. 2.The second groove 23 corresponds to the first groove 13, and the fourth groove 24 corresponds to the third groove 14. Moreover, the second groove 23 and the fourth groove 24 extend to the negative electrode current collector 21 along the thickness direction of the electrode assembly 100, leaving a sufficient space for the welding burr of the positive electrode tab 41 to prevent the welding burr from penetrating the second groove 23. Even if the welding burr penetrates the second groove 23, the positive electrode current collector 11 electrically connected to the positive electrode tab 41 contacts the negative electrode current collector 21 instead of the negative electrode active material layer 22, preventing the most dangerous short circuit situation from occurring. A first protective rubber 50 is further provided in the second groove 23 and the fourth groove 24 to resolve thickness differences occurring after the active material is removed from the groove itself, ensure consistency in thickness between the groove portion and the main body region of the electrode sheet, maintain consistency in cycle performance of the electrode assembly 100, and improve dynamic performance of the electrode assembly 100. The first protective rubber 50 may be any material that has insulating properties and can compensate for thickness differences in the groove portion, including, but not limited to, an adhesive tape or other fluid filler adhesive.

[0039] Referring again to FIG. 2, the thickness of the first protective rubber 50 along the thickness direction of the electrode assembly 100 is smaller than or equal to the depth of the second groove 23 and the fourth groove 24 to prevent the first protective rubber 50 from overflowing onto the separator 30 after filling the grooves, resulting in an increase in thickness in 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 groove, and a gap is provided between the periphery of the first protective rubber 50 and the negative electrode active material layer 22, thereby solving the overflow problem when the first protective rubber 50 is filled. In other embodiments, the periphery of the first protective rubber 50 can contact the negative electrode active material layer 22, but the present application is not limited thereto.

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

[0041] 2 and 3, 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 cover the first groove 13 and the third groove 14, respectively, and cover a part of the positive electrode active material layer 12. The two second insulating members 70 cover the second groove 23 and the fourth groove 24, respectively, and cover a part of the negative electrode active material layer 22. When the positive electrode active material layer 12 and the negative electrode active material layer 22 are equal in size, 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, and there are sufficient lithium embedding positions in the negative electrode sheet 20, so that the positive projected area of ​​the first insulating member 60 is larger than the positive projected area of ​​the second insulating member 70 along the lamination direction of the positive electrode sheet 10 and the negative electrode sheet 20 in order to reduce the occurrence of lithium precipitation problems. Specifically, the width of the first insulating member 60 is larger than the width of the second insulating member 70 along the direction indicated by the arrow A in FIG. 2.

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

[0043] In this embodiment, along the direction indicated by the arrow B in FIG. 2, the width of the first protective rubber 50 is W1, the width of the second 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である。

[0044] The positive electrode sheet 10 has a first side 103 and a second side 104 that are disposed 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 a direction extending from the first side 103 to the second side 104, i.e., in a direction indicated by an arrow C in FIG. 3, the first protective rubber 50 has a length L1, the second groove 23 has a length L2, the second insulating member 70 has a length L3, and the first insulating member 60 has a length L4. Here, L1 <L2<L3<L4である。

[0045] 2, the thickness of the first protective rubber is T1 and the depth of the second groove 23 is T2, where T1≦T2. The size of the first groove 13 is the same as the size of the third groove 14. The size of the second groove 23 is the same as the size of the fourth groove 24.

[0046] According to the needs of dimensional design, the dimensional relationship between the second 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 actual thickness of the negative electrode active material layer 22 after compaction.

[0047] The dimensional relationship between the second 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 manner as the positive electrode tab 41, and may be appropriately modified 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] 4, 5 and 6, the electrode assembly 200 according to the second embodiment is substantially the same as the electrode assembly 100 according to the first embodiment, but differs in that the negative electrode sheet 20 of the electrode assembly 200 does not have the second insulating member 70 that covers the second groove 23 and the fourth groove 24. By omitting the second insulating member 70, the size of the first insulating member 60 can be reduced, which contributes to improving the energy density of the electrode assembly 200.

[0051] In the second embodiment, the dimensional relationships between the second groove 23 and the first protective rubber 50 are 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 recessed 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 when cured. 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 contacts the negative electrode active material layer 22 unintentionally.

[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 groove 23 satisfies 1 mm≦L4-L2≦10 mm and 1 mm≦W4-W2≦10 mm.

[0059] [Fifth embodiment] As shown in Figures 13, 14 and 15, the electrode assembly 500 according to the fifth embodiment is almost the same as the electrode assembly 400 according to 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 groove 13 and the third groove 14. The structure of the electrode assembly 500 can eliminate the thickness space occupied by the first insulating member 60 and the second insulating member 70, and increase the energy density of the electrode assembly 500. In addition, the filling of the first protective rubber 50 and the second protective rubber 80 can provide an insulating effect, ensure the surface flatness of the electrode sheet, and reduce the thickness difference between the groove portion and the main body of the electrode sheet.

[0060] The second protective rubber 80 is filled in the first groove 13 and the third groove 14 with equal areas, and the periphery of the second protective rubber 80 is in contact with the positive electrode active material layer 12. The second protective rubber 80 does not become fluid after hardening. Eliminating the gaps in the grooves is advantageous in preventing the active material from overflowing when the electrode assembly 500 is subsequently pressurized and in improving the pressure resistance and service life of the electrode assembly 500.

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

[0062] 14 and 15 again, in the fifth embodiment, the width of the second protective rubber 80 is W5, which is the same as the width of the first groove 13. The length of the second protective rubber 80 is L5, which is the same as the length of the first groove 13. The first groove 13 has the same size as the third groove 14 and a depth of T3. The thickness of the second protective rubber 80 is T4, where 0 μm≦T4-T3≦20 μm. The thickness of the second protective rubber 80 is less than or equal to the depth of the first groove 13 and the third 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 groove 23 is W2, and the length of the second groove 23 is L2, where 1 mm≦L2-L0≦5 mm, and 1 mm≦W2-W0≦5 mm.

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

[0065] An embodiment of the present application further provides an electrochemical device comprising a packaging case (not shown) and an electrode assembly described in any one of the above examples or combinations of examples, wherein the electrode assembly is contained in the packaging case.

[0066] The above embodiments are only used to describe the technical aspects of the present application, and do not limit the present application. Although the present application 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 symbols]

[0067] 100, 200, 300, 400, 500 electrode assemblies 10 Positive electrode sheet 101 1st end 102 2nd end 103 1st side 104 Second side 11 Positive electrode current collector 12 Cathode active material layer 13 First groove 14 Third groove 20 Negative electrode sheet 21 Negative electrode current collector 22 Negative electrode active material layer 23 Second groove 24 4th groove 30 Separator 41 Positive tab 42 Negative 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 a 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 a 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, the positive electrode active material layer is provided with a first groove, one end of the positive electrode tab is provided in the first groove and is electrically connected to the positive electrode current collector; a second groove is provided in the negative electrode active material layer, the second groove corresponds to the first groove, the second groove extends to the negative electrode current collector along a thickness direction of the electrode assembly, and a first protective rubber is provided inside the second groove; The positive electrode sheet is provided with a first insulating member covering the first groove, the negative electrode sheet is provided with a second insulating member covering the second groove,

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

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

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

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

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

7. 2. The electrode assembly of claim 1, wherein the second groove has a width W2, the second insulating member has a width W3, and the first insulating member has a width W4, where W2<W3<W4.

8. The electrode assembly of claim 1 , wherein the second insulating member covers a portion of the negative electrode active material layer.

9. The electrode assembly according to claim 1 , wherein a projected area of ​​the first insulating member is larger than a projected area of ​​the second insulating member in a thickness direction of the electrode assembly.

10. a positive electrode sheet including a positive electrode current collector and a positive electrode active material layer provided on a 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 a 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, the positive electrode active material layer is provided with a first groove, one end of the positive electrode tab is provided in the first groove and is electrically connected to the positive electrode current collector; a second groove is provided in the negative electrode active material layer, the second groove corresponds to the first groove, the second groove extends to the negative electrode current collector along a thickness direction of the electrode assembly, and a first protective rubber is provided inside the second groove; The electrode assembly further comprises a second protective rubber provided within the first groove.

11. The electrode assembly according to claim 10 , wherein a peripheral portion of the second protective rubber is in contact with the positive electrode active material layer.

12. 12. An electrochemical device comprising: a packaging case; and the electrode assembly according to claim 1, wherein the electrode assembly is contained in the packaging case.

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