Electrode assembly and battery cell

Abstract

The utility model provides a kind of electrode assembly and electric core, electrode assembly is winding type structure, electrode assembly includes first pole piece, second pole piece and diaphragm, diaphragm is spaced between first pole piece and second pole piece;The innermost circle of first pole piece includes first corner section, and first corner section is oppositely arranged with the winding start end of second pole piece;The innermost circle of second pole piece includes second corner section, and second corner section is oppositely arranged with the winding start end of first pole piece;First pole piece is equipped with first active material layer, and second pole piece is equipped with second active material layer, in the winding direction of electrode assembly, tail end of first active material layer and tail end of second active material layer are flush;The distance between the winding start end of first pole piece and the winding start end of second pole piece is D1;The distance between the head end and tail end of first active material layer is D2, and the distance between the head end and tail end of second active material layer is D3, wherein, 1mm≤|D2-D3|-D1≤20mm.

Description

Technical Field

[0001] This utility model relates to the field of battery cell technology, and in particular to an electrode assembly and a battery cell. Background Technology

[0002] A wound-core battery cell is made by winding a positive electrode plate, a negative electrode plate, and a separator.

[0003] In related technologies, the winding structure of battery cells is prone to problems of being too tight or too loose, which affects the performance of the battery cells. Utility Model Content

[0004] This utility model provides an electrode assembly to solve the problem that the winding structure of the battery cell in the related art is often too tight or too loose.

[0005] The electrode assembly of this utility model embodiment has a wound structure, and the electrode assembly includes a first electrode, a second electrode, and a diaphragm, with the diaphragm spaced between the first electrode and the second electrode.

[0006] The innermost ring of the first electrode includes a first corner segment, which is disposed opposite to the winding start end of the second electrode; the innermost ring of the second electrode includes a second corner segment, which is disposed opposite to the winding start end of the first electrode.

[0007] The first electrode has a first active material layer, and the second electrode has a second active material layer;

[0008] In the winding direction of the electrode assembly, the tail ends of the first active material layer and the second active material layer are flush; the distance between the winding start end of the first electrode and the winding start end of the second electrode is D1; ​​the distance between the start and end ends of the first active material layer is D2, and the distance between the start and end ends of the second active material layer is D3, wherein 1mm≤|D2-D3|-D1≤20mm.

[0009] It is understandable that |D2-D3|-D1 represents the length of the first or second corner segment.

[0010] If the length of the first corner segment or the second corner segment is too large, it means that the winding structure of the electrode assembly in this utility model embodiment is too loose.

[0011] If the length of the first or second corner segment is too small, it means that the winding structure of the electrode assembly in this embodiment of the present invention is too tight.

[0012] Therefore, by satisfying |D2-D3|-D1 ≤ 1mm ≤ |D2-D3|-D1 ≤ 20mm, the electrode assembly of this utility model has a suitable winding structure tightness, which can avoid the problem of the winding structure being too tight or too loose, and thus avoid affecting the performance of the battery cell.

[0013] Therefore, the winding structure of the electrode assembly in this embodiment of the present invention has a suitable tightness, which can avoid the problem of the winding structure being too tight or too loose, thereby avoiding affecting the performance of the battery cell.

[0014] Optionally, the distance D1 between the winding start end of the first electrode and the winding start end of the second electrode, the distance D2 between the first and last ends of the first active material layer, and the distance D3 between the first and last ends of the second active material layer satisfy 0.5mm≤|D2-D3|-D1≤10mm.

[0015] Optionally, the electrode assembly further includes an insulating element disposed between the innermost ring of the first electrode and the winding start end of the second electrode.

[0016] Optionally, the innermost ring of the first electrode sheet further includes a first straight section and a second straight section, wherein the first straight section, the first corner section and the second straight section are arranged sequentially along the winding direction of the first electrode sheet;

[0017] The innermost ring of the second electrode also includes a third straight section and a fourth straight section, wherein the third straight section, the second corner section and the fourth straight section are arranged sequentially along the winding direction of the second electrode.

[0018] Optionally, the insulating member includes a first segment, a second segment, and a third segment arranged sequentially in the winding direction of the first electrode sheet. The first segment is disposed between the first straight segment and the third straight segment; the second segment is disposed between the first corner segment and the winding start end of the second electrode sheet; and the third segment is disposed between the second straight segment and the third straight segment.

[0019] In the winding direction of the electrode assembly, the length L1 of the overlapping area between the first segment and the third straight segment is 0.5mm-15mm, and the length L2 of the overlapping area between the third segment and the third straight segment is 0.5mm-15mm.

[0020] Optionally, along the winding direction of the electrode assembly, the starting end of the winding of the diaphragm is flush with the starting end of the winding of the first electrode sheet, or...

[0021] The starting end of the diaphragm extends beyond the starting end of the first electrode, and the distance between the starting end of the diaphragm and the starting end of the first electrode does not exceed 10 mm.

[0022] Optionally, the first electrode is a positive electrode, the second electrode is a negative electrode, and the separator includes a first separator and a second separator located on both sides of the positive electrode;

[0023] The first diaphragm includes a first winding start section, which is located on the side of the first straight section facing the third straight section;

[0024] The second diaphragm includes a second winding start section located on the side of the first straight section facing the fourth straight section;

[0025] The insulating element bypasses the starting end of the winding of the negative electrode sheet, and the insulating element is disposed between the positive electrode sheet and the first separator.

[0026] Optionally, along the winding direction of the electrode assembly, the starting end of the winding of the diaphragm is flush with the starting end of the winding of the second electrode sheet, or...

[0027] The starting end of the diaphragm extends beyond the starting end of the second electrode, and the distance between the starting end of the diaphragm and the starting end of the second electrode does not exceed 10 mm.

[0028] Optionally, the first electrode is a positive electrode, the second electrode is a negative electrode, and the separator includes a first separator and a second separator located on both sides of the negative electrode;

[0029] The first diaphragm includes a first winding start section, which is located on the side of the third straight section facing the second straight section;

[0030] The second diaphragm includes a second winding start section, which is located on the side of the third straight section facing the first straight section;

[0031] The insulating component bypasses the starting end of the winding of the negative electrode sheet. The first segment is disposed between the first diaphragm and the first straight segment. The third segment is disposed between the second diaphragm and the second straight segment. The second segment is disposed between the first corner segment and the starting end of the winding of the second electrode sheet.

[0032] This utility model also provides a battery cell.

[0033] The battery cell of this utility model embodiment includes the electrode assembly described in the above embodiment.

[0034] The battery cell of this utility model embodiment, by including the electrode assembly of the above embodiment, can avoid the problem of the battery cell winding structure being too tight or too loose, thereby avoiding affecting the performance of the battery cell. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the electrode assembly according to an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the structure of an electrode assembly according to another embodiment of the present invention;

[0038] Figure 3 This is an unfolded view of the first electrode sheet according to an embodiment of the present utility model;

[0039] Figure 4 This is an unfolded view of the second electrode sheet according to an embodiment of the present invention.

[0040] In the diagram: 1. First pole piece; 101. First corner segment; 102. First straight segment; 103. Second straight segment;

[0041] 2. Second pole piece; 201. Second corner segment; 202. Third straight segment; 203. Fourth straight segment;

[0042] 3. Insulating components; 301. First section; 302. Second section; 303. Third section;

[0043] 4. Diaphragm;

[0044] 401, First diaphragm; 4011, First winding start section;

[0045] 402. Second diaphragm; 4021. Second winding starting section;

[0046] 5. First active material layer;

[0047] 6. Second active material layer. Detailed Implementation

[0048] To make the technical problems solved, technical solutions, and beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0049] In the description of this utility model, it should be understood that the terms "longitudinal," "radial," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0050] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal encapsulation of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0051] To address the issue that the winding structure of battery cells in related technologies is prone to being too tight or too loose.

[0052] This invention provides an electrode assembly.

[0053] The electrode assembly of this utility model embodiment is a wound structure. The electrode assembly includes a first electrode 1, a second electrode 2 and a diaphragm 4, with the diaphragm 4 spaced between the first electrode 1 and the second electrode 2.

[0054] The innermost ring of the first electrode 1 includes a first corner segment 101, which is positioned opposite to the winding start end of the second electrode 2; the innermost ring of the second electrode 2 includes a second corner segment 201, which is positioned opposite to the winding start end of the first electrode 1.

[0055] The first electrode 1 has a first active material layer 5, and the second electrode 2 has a second active material layer 6.

[0056] In the winding direction of the electrode assembly, the tail ends of the first active material layer 5 and the second active material layer 6 are flush; the distance between the winding start end of the first electrode 1 and the winding start end of the second electrode 2 is D1; ​​the distance between the start and end ends of the first active material layer 5 is D2, and the distance between the start and end ends of the second active material layer 6 is D3, wherein 1mm≤|D2-D3|-D1≤20mm.

[0057] It is understandable that |D2-D3|-D1 is the length of the first corner segment 101 or the second corner segment 201.

[0058] If the length of the first corner segment 101 or the second corner segment 201 is too large, it means that the winding structure of the electrode assembly in this utility model embodiment is too loose.

[0059] If the length of the first corner segment 101 or the second corner segment 201 is too small, it means that the winding structure of the electrode assembly in this utility model embodiment is too tight.

[0060] Therefore, by satisfying |D2-D3|-D1 ≤ 1mm ≤ |D2-D3|-D1 ≤ 20mm, the electrode assembly of this utility model has a suitable winding structure tightness, which can avoid the problem of the winding structure being too tight or too loose, and thus avoid affecting the performance of the battery cell.

[0061] Therefore, the winding structure of the electrode assembly in this embodiment of the present invention has a suitable tightness, which can avoid the problem of the winding structure being too tight or too loose, thereby avoiding affecting the performance of the battery cell.

[0062] In some embodiments, the distance D1 between the winding start end of the first electrode 1 and the winding start end of the second electrode 2, the distance D2 between the first and last ends of the first active material layer 5 and the distance D3 between the first and last ends of the second active material layer 6 satisfy 0.5mm≤|D2-D3|-D1≤10mm.

[0063] In some embodiments, the electrode assembly further includes an insulating member 3 disposed between the innermost ring of the first electrode 1 and the winding start end of the second electrode 2.

[0064] It is understandable that the insulating component 3 can be made of a non-conductive material, such as plastic or rubber.

[0065] The insulating element 3 being disposed between the innermost ring of the first electrode 1 and the winding start end of the second electrode 2 means that: the insulating element 3 can be disposed on the side of the innermost ring of the first electrode 1 facing the winding start end of the second electrode 2, the insulating element 3 can also be disposed on the winding start end of the second electrode 2, or the insulating element 3 can be disposed in the gap that separates the innermost ring of the first electrode 1 and the winding start end of the second electrode 2.

[0066] It is worth noting that if the insulating element 3 is disposed on the diaphragm 4 at the starting end of the winding of the second electrode 2, it can also be considered that the insulating element 3 is disposed at the starting end of the winding of the second electrode 2.

[0067] Therefore, by providing an insulating member 3 between the winding start end of the second electrode 2 and the innermost ring of the first electrode 1, even if the cell containing the electrode assembly of this utility model is dropped or subjected to a drop test, and the winding start ends of the first electrode 1 and the second electrode 2, which were originally flush, are no longer flush or the distance between them increases, thus exposing the winding start end of the second electrode 2, there will be no short circuit caused by the winding start end of the second electrode 2 contacting the first electrode 1.

[0068] Furthermore, the innermost ring of the first electrode 1 also includes a first straight section 102 and a second straight section 103, with the first straight section 102, the first corner section 101 and the second straight section 103 arranged sequentially along the winding direction of the first electrode 1.

[0069] The winding start end of the second electrode 2 is disposed opposite to the first corner segment 101. At least a portion of the insulating member 3 is disposed between the first corner segment 101 and the winding start end of the second electrode 2. It can be understood that the first corner segment 101 is the first corner segment of the innermost ring of the first electrode 1 in the winding direction.

[0070] The innermost ring of the second electrode 2 also includes a third straight section 202 and a fourth straight section 203, which are arranged sequentially along the winding direction of the second electrode 2.

[0071] The second corner segment 201 is positioned opposite to the winding start end of the first electrode 1. It can be understood that the second corner segment 201 is the first corner segment of the innermost ring of the second electrode 2 in the winding direction.

[0072] Furthermore, the insulating component 3 includes a first segment 301, a second segment 302, and a third segment 303 arranged sequentially in the winding direction of the first electrode 1. The first segment 301 is disposed between the first straight segment 102 and the third straight segment 202; the second segment 302 is disposed between the first corner segment 101 and the winding start end of the second electrode 2; and the third segment 303 is disposed between the second straight segment 103 and the third straight segment 202.

[0073] The first segment 301 of the insulating component 3 is set to correspond to the first straight segment 102 of the first electrode 1, the second segment 302 of the insulating component 3 is set to correspond to the first corner segment 101 of the first electrode 1, and the third segment 303 of the insulating component 3 is set to correspond to the second straight segment 103 of the first electrode 1.

[0074] Therefore, by providing an insulating member 3 between the winding start end of the second electrode 2 and the innermost ring of the first electrode 1, even if the cell containing the electrode assembly of this utility model is dropped or subjected to a drop test, and the winding start ends of the first electrode 1 and the second electrode 2, which were originally flush, are no longer flush or the distance between them increases, thus exposing the winding start end of the second electrode 2, there will be no short circuit caused by the winding start end of the second electrode 2 contacting the first electrode 1.

[0075] In some embodiments, in the winding direction of the electrode assembly, the length L1 of the overlapping area of ​​the first segment 301 and the third straight segment 202 is 0.5mm-15mm.

[0076] It is understandable that an adhesive can be applied to the overlapping area of ​​the first segment 301 and the third straight segment 202 to bond the first segment 301 to the third straight segment 202. Therefore, the size of the overlapping area of ​​the first segment 301 and the third straight segment 202 directly affects the connection strength between the first segment 301 and the third straight segment 202.

[0077] In the length direction of the electrode assembly, the longer the overlapping area between the first segment 301 and the third straight segment 202, the greater the adhesive force between the first segment 301 and the third straight segment 202; the shorter the overlapping area between the first segment 301 and the third straight segment 202, the smaller the adhesive force between the first segment 301 and the third straight segment 202.

[0078] Therefore, in the electrode assembly of this utility model embodiment, the length L1 of the overlapping area between the first segment 301 and the third straight segment 202 is set to 0.5mm-15mm. This can meet the bonding force requirements between the first segment 301 and the third straight segment 202, while avoiding the problem of material waste caused by the excessive length of the overlapping area between the first segment 301 and the third straight segment 202.

[0079] In some embodiments, the length L2 of the overlapping area between the third segment 303 and the third straight segment 202 in the longitudinal direction of the electrode assembly is 0.5mm-15mm.

[0080] It is understandable that an adhesive can be applied to the overlapping area of ​​the third segment 303 and the third straight segment 202 to bond the third segment 303 to the third straight segment 202. Therefore, the size of the overlapping area of ​​the third segment 303 and the third straight segment 202 directly affects the connection strength between the third segment 303 and the third straight segment 202.

[0081] In the length direction of the electrode assembly, the longer the overlapping area between the third segment 303 and the third straight segment 202, the greater the adhesive force between the third segment 303 and the third straight segment 202; the shorter the overlapping area between the third segment 303 and the third straight segment 202, the smaller the adhesive force between the third segment 303 and the third straight segment 202.

[0082] Therefore, in the electrode assembly of this utility model embodiment, the length L2 of the overlapping area between the third segment 303 and the third straight segment 202 is set to 0.5mm-15mm. This can meet the bonding force requirements between the third segment 303 and the third straight segment 202, while avoiding the problem of material waste caused by the excessive length of the overlapping area between the third segment 303 and the third straight segment 202.

[0083] In some embodiments, along the winding direction of the electrode assembly,

[0084] The starting end of the winding of the diaphragm 4 is flush with the starting end of the winding of the first electrode 1, or

[0085] The starting end of the diaphragm 4 extends beyond the starting end of the first electrode 1, and the distance between the starting end of the diaphragm 4 and the starting end of the first electrode 1 does not exceed 10 mm.

[0086] It is understandable that the winding start end of the first electrode 1 is the end where the first electrode 1 is first wound in, and the winding start end of the diaphragm 4 is the end where the diaphragm 4 is first wound in. The winding start end of the diaphragm 4 can be flush with the winding start end of the first electrode 1; the winding start end of the diaphragm 4 can also extend beyond the winding start end of the first electrode 1.

[0087] Therefore, by extending the starting end of the diaphragm 4 beyond the starting end of the first electrode 1, and setting the distance of the starting end of the diaphragm 4 extending beyond the starting end of the first electrode 1 to no more than 10cm, it is possible to avoid the starting end of the first electrode 1 being exposed between the diaphragms 4 on both sides of the first electrode 1 due to the shrinkage of the diaphragm 4, thereby reducing the possibility of a short circuit caused by the starting end of the first electrode 1 contacting the second electrode 2; at the same time, it is also possible to avoid the starting end of the diaphragm 4 extending too far beyond the starting end of the first electrode 1, which would increase the size of the battery cell and the manufacturing cost.

[0088] In some embodiments, the first electrode 1 is a positive electrode, the second electrode 2 is a negative electrode, and the separator 4 includes a first separator 401 and a second separator 402 located on both sides of the positive electrode.

[0089] The first diaphragm 401 includes a first winding start section 4011, which is located on the side of the first straight section 102 facing the third straight section 202.

[0090] The second diaphragm 402 includes a second winding start section 4021, which is located on the side of the first straight section 102 facing the fourth straight section 203.

[0091] The insulating member 3 bypasses the starting end of the winding of the negative electrode plate, and the insulating member 3 is disposed between the positive electrode plate and the first diaphragm 401.

[0092] By setting the separator 4 as a first separator 401 and a second separator 402, and respectively disposed on both sides of the positive electrode sheet, that is, before winding the positive electrode sheet, the first separator 401 and the second separator 402 can be pressed onto both sides of the positive electrode sheet in advance, and then the positive electrode sheet can be wound, which can reduce the winding difficulty of the electrode assembly of this utility model embodiment.

[0093] In some embodiments, along the winding direction of the electrode assembly,

[0094] The starting end of the winding of the diaphragm 4 is flush with the starting end of the winding of the second electrode 2, or

[0095] The starting end of the winding of the diaphragm 4 extends out of the starting end of the winding of the second electrode 2, and the distance between the starting end of the winding of the diaphragm 4 and the starting end of the winding of the second electrode 2 does not exceed 10mm.

[0096] It is understandable that the winding start end of the second electrode 2 is the end where the second electrode 2 is first wound in, and the winding start end of the diaphragm 4 is the end where the diaphragm 4 is first wound in. The winding start end of the diaphragm 4 can be flush with the winding start end of the second electrode 2; the winding start end of the diaphragm 4 can also extend beyond the winding start end of the second electrode 2.

[0097] Therefore, by extending the starting end of the diaphragm 4 beyond the starting end of the second electrode 2, and setting the distance of the starting end of the diaphragm 4 extending beyond the starting end of the second electrode 2 to no more than 10cm, it is possible to avoid the starting end of the second electrode 2 being exposed between the diaphragms 4 on both sides of the second electrode 2 due to the shrinkage of the diaphragm 4, thereby reducing the possibility of a short circuit caused by the starting end of the second electrode 2 contacting the first electrode 1; at the same time, it is also possible to avoid increasing the size and manufacturing cost of the battery cell due to the starting end of the diaphragm 4 extending too far beyond the starting end of the second electrode 2.

[0098] In some embodiments, the first electrode 1 is a positive electrode, the second electrode 2 is a negative electrode, and the separator 4 includes a first separator 401 and a second separator 402 located on both sides of the negative electrode.

[0099] The first diaphragm 401 includes a first winding start section 4011, which is located on the side of the third straight section 202 facing the second straight section 103.

[0100] The second diaphragm 402 includes a second winding start section 4021, which is located on the side of the third straight section 202 facing the first straight section 102.

[0101] The insulating component 3 bypasses the starting end of the winding of the negative electrode sheet. The first segment 301 is disposed between the first diaphragm 401 and the first straight segment 102. The third segment 303 is disposed between the second diaphragm 402 and the second straight segment 103. The second segment 302 is disposed between the first corner segment 101 and the starting end of the winding of the second electrode sheet.

[0102] Furthermore, an adhesive can be applied to the overlapping area of ​​the first segment 301 and the third straight segment 202 to bond the first segment 301 to the first diaphragm 401. Therefore, the size of the overlapping area of ​​the first segment 301 and the third straight segment 202 directly affects the connection strength between the first segment 301 and the first diaphragm 401.

[0103] In the length direction of the electrode assembly, the longer the overlapping area between the first segment 301 and the third straight segment 202, the greater the adhesive force between the first segment 301 and the first diaphragm 401; the shorter the overlapping area between the first segment 301 and the third straight segment 202, the smaller the adhesive force between the first segment 301 and the first diaphragm 401.

[0104] Therefore, in the electrode assembly of this utility model embodiment, the length L1 of the overlapping area between the first segment 301 and the third straight segment 202 is set to 0.5mm-15mm. This can meet the adhesion requirements between the first segment 301 and the first diaphragm 401, while avoiding the problem of material waste caused by the excessive length of the overlapping area between the first segment 301 and the third straight segment 202.

[0105] Furthermore, an adhesive can be applied to the overlapping area of ​​the third segment 303 and the third straight segment 202 to bond the third segment 303 to the second diaphragm 402. Therefore, the size of the overlapping area of ​​the third segment 303 and the third straight segment 202 directly affects the connection strength between the third segment 303 and the second diaphragm 402.

[0106] In the length direction of the electrode assembly, the longer the overlapping area between the third segment 303 and the third straight segment 202, the greater the adhesive force between the third segment 303 and the second diaphragm 402; the shorter the overlapping area between the third segment 303 and the third straight segment 202, the smaller the adhesive force between the third segment 303 and the second diaphragm 402.

[0107] Therefore, in the electrode assembly of this utility model embodiment, the length L2 of the overlapping area between the third segment 303 and the third straight segment 202 is set to 0.5mm-15mm. This can meet the adhesion requirements between the third segment 303 and the second diaphragm 402, while avoiding the problem of material waste caused by the excessive length of the overlapping area between the third segment 303 and the third straight segment 202.

[0108] This utility model also provides a battery cell.

[0109] The battery cell of this utility model embodiment includes the electrode assembly described in the above embodiment.

[0110] The battery cell of this utility model embodiment, by including the electrode assembly of the above embodiment, can avoid the problem of the battery cell winding structure being too tight or too loose, thereby avoiding affecting the performance of the battery cell.

[0111] The above-described embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model, and should all be included within the protection scope of this utility model.

Claims

1. An electrode assembly, characterized in that, The electrode assembly has a wound structure and includes a first electrode (1), a second electrode (2) and a diaphragm (4). The diaphragm (4) is spaced between the first electrode (1) and the second electrode (2). The innermost ring of the first electrode (1) includes a first corner segment (101), which is disposed opposite to the winding start end of the second electrode (2); the innermost ring of the second electrode (2) includes a second corner segment (201), which is disposed opposite to the winding start end of the first electrode (1); The first electrode (1) is provided with a first active material layer (5), and the second electrode (2) is provided with a second active material layer (6). In the winding direction of the electrode assembly, the tail ends of the first active material layer (5) and the second active material layer (6) are flush. The distance between the winding start end of the first electrode (1) and the winding start end of the second electrode (2) is D1; ​​the distance between the first end and the tail end of the first active material layer (5) is D2, and the distance between the first end and the tail end of the second active material layer (6) is D3, wherein 1mm≤|D2-D3|-D1≤20mm.

2. The electrode assembly according to claim 1, characterized in that, The distance D1 between the winding start end of the first electrode (1) and the winding start end of the second electrode (2), the distance D2 between the first and last ends of the first active material layer (5) and the distance D3 between the first and last ends of the second active material layer (6) satisfy 0.5mm≤|D2-D3|-D1≤10mm.

3. The electrode assembly according to claim 1, characterized in that, The electrode assembly further includes an insulating element (3), which is disposed between the innermost ring of the first electrode (1) and the winding start end of the second electrode (2).

4. The electrode assembly according to claim 3, characterized in that, The innermost ring of the first electrode (1) also includes a first straight section (102) and a second straight section (103), and the first straight section (102), the first corner section (101) and the second straight section (103) are arranged sequentially along the winding direction of the first electrode (1); The innermost ring of the second electrode (2) also includes a third straight section (202) and a fourth straight section (203), wherein the third straight section (202), the second corner section (201) and the fourth straight section (203) are arranged sequentially along the winding direction of the second electrode (2).

5. The electrode assembly according to claim 4, characterized in that, The insulating component (3) includes a first segment (301), a second segment (302), and a third segment (303) arranged sequentially in the winding direction of the first electrode (1). The first segment (301) is disposed between the first straight segment (102) and the third straight segment (202); the second segment (302) is disposed between the first corner segment (101) and the winding start end of the second electrode (2); and the third segment (303) is disposed between the second straight segment (103) and the third straight segment (202). In the winding direction of the electrode assembly, the length L1 of the overlapping area between the first segment (301) and the third straight segment (202) is 0.5mm-15mm, and the length L2 of the overlapping area between the third segment (303) and the third straight segment (202) is 0.5mm-15mm.

6. The electrode assembly according to claim 4, characterized in that, Along the winding direction of the electrode assembly, the starting end of the winding of the diaphragm (4) is flush with the starting end of the winding of the first electrode (1), or, The starting end of the diaphragm (4) extends beyond the starting end of the first electrode (1), and the distance between the starting end of the diaphragm (4) and the starting end of the first electrode (1) does not exceed 10 mm.

7. The electrode assembly according to claim 6, characterized in that, The first electrode (1) is a positive electrode, the second electrode (2) is a negative electrode, and the diaphragm (4) includes a first diaphragm (401) and a second diaphragm (402) located on both sides of the positive electrode. The first diaphragm (401) includes a first winding start section (4011) located on the side of the first straight section (102) facing the third straight section (202); The second diaphragm (402) includes a second winding start section (4021) located on the side of the first straight section (102) facing the fourth straight section (203); The insulating element (3) bypasses the starting end of the winding of the negative electrode sheet, and the insulating element (3) is disposed between the positive electrode sheet and the first separator (401).

8. The electrode assembly according to claim 5, characterized in that, Along the winding direction of the electrode assembly, the starting end of the winding of the diaphragm (4) is flush with the starting end of the winding of the second electrode (2), or... The starting end of the diaphragm (4) extends beyond the starting end of the second electrode (2), and the distance between the starting end of the diaphragm (4) and the starting end of the second electrode (2) does not exceed 10 mm.

9. The electrode assembly according to claim 8, characterized in that, The first electrode (1) is a positive electrode, the second electrode (2) is a negative electrode, and the diaphragm (4) includes a first diaphragm (401) and a second diaphragm (402) located on both sides of the negative electrode. The first diaphragm (401) includes a first winding start section (4011), which is located on the side of the third straight section (202) facing the second straight section (103); The second diaphragm (402) includes a second winding start section (4021) located on the side of the third straight section (202) facing the first straight section (102); The insulating element (3) bypasses the starting end of the winding of the negative electrode sheet. The first segment (301) is disposed between the first diaphragm (401) and the first straight segment (102). The third segment (303) is disposed between the second diaphragm (402) and the second straight segment (103). The second segment (302) is disposed between the first corner segment (101) and the starting end of the winding of the second electrode sheet (2).

10. A battery cell, characterized in that, Includes the electrode assembly as described in any one of claims 1-9.

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