Battery cell and battery

Abstract

This utility model discloses a battery cell and battery, relating to the field of new energy technology. The battery cell of this application includes an electrode assembly, a third electrode, and a fixing member. The electrode assembly includes a first electrode and a second electrode stacked along the thickness direction of the battery cell, with opposite polarities. Along the thickness direction of the battery cell, a third electrode is disposed on one side of the electrode assembly, with the third electrode having the same polarity as the first or second electrode. The third electrode has an outer surface away from the electrode assembly, and a first groove is provided on the outer surface of the third electrode. The fixing member includes a first fixing member disposed in the first groove. The first fixing member of this application is disposed in the first groove on the outer surface of the third electrode. The first fixing member can be made of adhesive wrapping or hot melt adhesive. Due to the design of the first groove, the first fixing member is embedded therein, reducing the protrusion height of the first fixing member, thereby effectively reducing the overall thickness of the battery cell and increasing the energy density.

Description

Technical Field

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

[0002] With the development of new energy technologies, further improving battery energy density has become a key focus for more and more battery manufacturers. The core component of a battery is the cell, which can be divided into wound cells and laminated cells based on different manufacturing processes and cell structures.

[0003] The outermost electrode of a laminated cell is often covered with adhesive wrapping and hot melt adhesive. However, the adhesive layer at the adhesive application point protrudes from the outermost electrode surface, thus occupying space along the thickness direction of the cell and affecting the energy density of the battery. Utility Model Content

[0004] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a battery cell that avoids the adhesive layer protruding from the outer peripheral surface of the cell, thereby improving the energy density of the cell.

[0005] This utility model also proposes a battery having the above-mentioned battery cell.

[0006] The battery cell according to a first aspect embodiment of the present invention includes:

[0007] An electrode assembly, comprising a first electrode and a second electrode stacked along the thickness direction of the battery cell, wherein the first electrode and the second electrode have opposite polarities;

[0008] The third electrode is disposed on one side of the electrode assembly along the thickness direction of the battery cell. The third electrode has the same polarity as the first electrode or the second electrode. The third electrode has an outer surface away from the electrode assembly, and the outer surface of the third electrode is provided with a first groove.

[0009] The fastener includes a first fastener disposed in the first groove.

[0010] The battery cell according to the embodiments of this utility model has at least the following beneficial effects:

[0011] The first fixing member of this application is disposed in a first groove on the outer surface of the third electrode. The first fixing member can be made of adhesive wrapping or hot melt adhesive. Due to the design of the first groove, the first fixing member is embedded therein, reducing the protrusion height of the first fixing member, thereby effectively reducing the overall thickness of the cell and improving the energy density.

[0012] According to some embodiments of the present invention, the fixing member further includes a second fixing member, the second fixing member being located on the side of the electrode assembly, the first fixing member including a first sub-fixing member and a second sub-fixing member, the second fixing member being integrally connected to the first sub-fixing member, and the second sub-fixing member having a gap with the edge of the third electrode.

[0013] According to some embodiments of the present invention, the first groove includes a first sub-groove for accommodating the first sub-fixing member and a second sub-groove for accommodating the second sub-fixing member.

[0014] According to some embodiments of the present invention, the first sub-groove includes at least a first-level groove and a second-level groove, the first-level groove communicates with the second-level groove, and the second-level groove is located on the side of the first-level groove away from the outer surface of the third electrode sheet;

[0015] And / or, the second sub-groove includes at least a third-level groove and a fourth-level groove, the third-level groove communicating with the fourth-level groove, and the fourth-level groove being located on the side of the third-level groove away from the outer surface of the third electrode.

[0016] According to some embodiments of the present invention, the battery cell further includes a fourth electrode plate. Along the thickness direction of the battery cell, the fourth electrode plate is disposed on the opposite side of the electrode plate assembly to the third electrode plate. The fourth electrode plate has an outer surface away from the electrode plate assembly. The fixing member further includes a third fixing member disposed on the outer surface of the fourth electrode plate. The third fixing member is integrally connected with the second fixing member.

[0017] According to some embodiments of the present invention, the outer surface of the fourth electrode is provided with a second groove for accommodating the third fixing member.

[0018] According to some embodiments of the present invention, the first sub-groove and the second groove are correspondingly arranged along the thickness direction of the battery cell.

[0019] According to some embodiments of the present invention, the fourth electrode includes a second current collector and a second active material layer, wherein the second active material layer is disposed on the inner surface of the second current collector near the electrode assembly.

[0020] According to some embodiments of the present invention, the third electrode includes a first current collector and a first active material layer, wherein the first active material layer is disposed on the inner surface of the first current collector near the electrode assembly.

[0021] According to some embodiments of the present invention, the first groove has a bottom wall that is bonded to the first fixing member, and the roughness of the bottom wall is greater than the roughness of the outer surface of the third electrode.

[0022] According to some embodiments of the present invention, the thickness L of the first current collector and the depth H of the first groove have the following relationship: 0.1L≤H≤0.75L, preferably 0.25L≤H≤0.5L.

[0023] According to some embodiments of the present invention, it further includes at least one of the following (1) to (3):

[0024] (1) The projected area S1 of the first sub-fixing member and the projected area S2 of the first sub-groove are 0.55≤S1 / S2≤0.95, preferably 0.64≤S1 / S2≤0.81.

[0025] (2) The projected area S3 of the second sub-fixing member and the projected area S4 of the second sub-groove are 0.55≤S3 / S4≤0.95, preferably 0.64≤S3 / S4≤0.81;

[0026] (3) The projected area S5 of the third fastener and the projected area S6 of the second groove are 0.55≤S5 / S6≤0.95, preferably 0.64≤S5 / S6≤0.81.

[0027] According to some embodiments of the present invention, the first groove includes a plurality of walls connected sequentially along the circumference of the first groove, with adjacent walls transitioning in an arc shape.

[0028] A battery according to a second aspect of the present invention includes a housing and a cell as described in any of the above embodiments, wherein the first fixing member includes a second sub-fixing member, and the housing is connected to the third electrode through the second sub-fixing member.

[0029] According to some embodiments of the present invention, the first fixing member is located in the first groove, and the thickness of the first fixing member is greater than the depth of the first groove, so that the first fixing member protrudes from the outer surface of the third electrode. Corresponding to the first groove, the inner wall surface of the housing is provided with a fourth groove, which is used to accommodate the first fixing member protruding from the outer surface of the third electrode.

[0030] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0032] Figure 1 This is a top view of the battery cell according to an embodiment of the present invention;

[0033] Figure 2 for Figure 1 Cross-sectional view of the battery cell along the AA direction;

[0034] Figure 3 for Figure 2 Enlarged view of region C in the middle;

[0035] Figure 4 for Figure 1 A cross-sectional view of the third electrode along the BB direction;

[0036] Figure 5 for Figure 4 A schematic diagram of another implementation of the third electrode plate;

[0037] Figure 6 This is a schematic diagram showing the fit between the battery casing and the third electrode in an embodiment of the present invention.

[0038] Figure label:

[0039] Electrode assembly 100; First electrode 110; Second electrode 120;

[0040] Third electrode 200; First groove 210; Third-level groove 2101; Fourth-level groove 2102; First sub-groove 211; Second sub-groove 212; First current collector 220; First surface 221; Second surface 222; First active material layer 230;

[0041] Fastener 300; First fastener 310; First sub-fastener 311; Second sub-fastener 312; Second fastener 320; Third fastener 330;

[0042] Fourth pole piece 400; Second groove 410;

[0043] Casing 500; Fourth groove 510; Detailed Implementation

[0044] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0045] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They 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. Therefore, they should not be construed as limitations on this utility model.

[0046] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0047] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0048] In the description of this utility model, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0049] With the development of new energy technologies, further improving battery energy density has become a key focus for more and more battery manufacturers. The core component of a battery is the cell, which can be divided into wound cells and laminated cells based on different manufacturing processes and cell structures.

[0050] The outermost electrode of a laminated cell is often covered with adhesive wrapping and hot melt adhesive. However, the adhesive layer at the adhesive application point protrudes from the outermost electrode surface, thus occupying space along the thickness direction of the cell and affecting the energy density of the battery.

[0051] It should be noted that the middle part of the adhesive wrapping is located on the periphery of the battery cell and extends along the thickness direction. The two ends of the adhesive wrapping are connected to the uppermost and lowermost electrode plates, respectively, thereby fixing the entire battery cell and preventing the stacked electrode plates from becoming loose or shifting during assembly or use. Hot melt adhesive is applied to the outermost electrode plate for connecting and fixing the outermost electrode plate to the housing. The outermost electrode plate is then connected to the remaining intermediate electrode plates through adhesive wrapping (or other connection methods) to form a whole, thus fixing the entire battery cell within the housing.

[0052] Therefore, in order to further improve the energy density of the battery cells in the prior art, this application makes further improvements to the battery cell structure, as follows:

[0053] The battery cell of this application includes an electrode assembly 100, a third electrode 200, and a fixing member 300. For example... Figure 1 and Figure 2 As shown, the electrode assembly 100 includes a first electrode 110 and a second electrode 120. The first electrode 110 and the second electrode 120 are stacked along the thickness direction of the battery cell. The first electrode 110 and the second electrode 120 have opposite polarities. For example, the first electrode 110 can be a positive electrode, and the second electrode 120 can be a negative electrode; if the first electrode 110 is a negative electrode, then the second electrode 120 is a positive electrode. It can be understood that both the first electrode 110 and the second electrode 120 are double-sided coated sheets.

[0054] Along the thickness direction of the battery cell, the third electrode 200 is disposed on one side of the electrode assembly 100, and the polarity of the third electrode 200 is opposite to that of the adjacent first electrode 110 or adjacent second electrode 120. That is, if the outermost part of the electrode assembly 100 is a positive electrode, then the third electrode 200 is a negative electrode, and vice versa. The third electrode 200 is a single-sided coated sheet, with the coated side facing the electrode assembly 100 and the uncoated side facing the housing 500. Figure 1 As shown, the third electrode 200 has an outer surface away from the electrode assembly 100, and a first groove 210 is provided on this outer surface. The fixing member 300 includes a first fixing member 310, which is disposed in the first groove 210 on the outer surface of the third electrode 200. The first fixing member 310 can be made of adhesive wrapping or hot melt adhesive. Due to the design of the first groove 210, the first fixing member 310 is embedded therein, reducing the protrusion height of the first fixing member 310, thereby effectively reducing the overall thickness of the cell and improving the energy density.

[0055] In some embodiments, such as Figures 1 to 3As shown, the first fixing member 310 includes a first sub-fixing member 311 and a second sub-fixing member 312. The first sub-fixing member 311 is the end of the adhesive wrapping, and the second sub-fixing member 312 is hot melt adhesive. The fixing member 300 also includes a second fixing member 320 located on the side of the electrode assembly 100. The second fixing member 320 is the middle part of the adhesive wrapping. Thus, the end of the second fixing member 320 is integrally connected with the first sub-fixing member 311. The second sub-fixing member 312 has a gap with the edge of the third electrode 200 to reduce the risk of hot melt adhesive overflow during the bonding and pressing process.

[0056] Furthermore, such as Figure 1 As shown, corresponding to the first sub-fixing member 311, the first groove 210 includes the first sub-groove 211, and the first sub-fixing member 311 is disposed in the first groove 210. The first sub-groove 211 is typically disposed at the edge of the third electrode 200, and an opening is formed on the outer periphery of the third electrode 200 to facilitate the connection between the second fixing member 320 and the first sub-fixing member 311. Corresponding to the second sub-fixing member 312, the first groove 210 includes the second sub-groove 212, and the second sub-groove 212 is located in the middle of the third electrode 200, maintaining a certain distance from the edge of the third electrode 200 to form a circumferentially closed groove structure.

[0057] In some embodiments, the first sub-groove 211 includes at least a first-level groove and a second-level groove (not shown in the figure, see reference). Figure 5 The third-level groove 2101 and the fourth-level groove 2102 shown are connected to the first-level groove, and the second-level groove is located on the side of the first-level groove away from the outer surface of the third electrode 200, that is, as shown in the figure. Figure 5 As shown, the second-level groove is located below the first-level groove. Similarly, the second sub-groove 212 may also include a third-level groove 2101 and a fourth-level groove 2102, with the third-level groove 2101 communicating with the fourth-level groove 2102, and the fourth-level groove 2102 located on the side of the third-level groove 2101 away from the outer surface of the third electrode 200.

[0058] Thus, the first and second level grooves form a stepped structure, increasing the bonding area and improving structural stability. Simultaneously, the stepped design effectively disperses stress, further enhancing the foil's tear resistance and optimizing its overall mechanical properties. The first and second level grooves can have the same or different shapes; for example, the first level groove can be square, while the second level groove can be either square or circular.

[0059] In some embodiments, such as Figure 2As shown, the battery cell also includes a fourth electrode 400, which is disposed on the opposite side of the electrode assembly 100 along the thickness direction. The fourth electrode 400 has an outer surface away from the electrode assembly 100. The fixing member 300 also includes a third fixing member 330 for connecting to the outer surface of the fourth electrode 400. The third fixing member 330 is integrally connected with the second fixing member 320. That is, the first fixing member 311 and the third fixing member 330 are respectively located at both ends of the second fixing member 320 and are bent relative to the second fixing member 320, thereby attaching to the outer surfaces of the third electrode 200 and the fourth electrode 400, respectively. It can be understood that the fourth electrode 400 has the opposite polarity to the adjacent first electrode 110 or the adjacent second electrode 120. That is, if the adjacent electrode is a positive electrode, then the fourth electrode 400 is a negative electrode, and vice versa.

[0060] Furthermore, the outer surface of the fourth electrode 400 is provided with a second groove 410 for accommodating the third fixing member 330. The design of the second groove 410 allows the third fixing member 330 to be embedded therein, reducing the protrusion height of the adhesive wrapping on the outer surface of the fourth electrode 400, further reducing the cell thickness and improving the overall structural compactness. It can be understood that the second groove 410 is located at the edge of the outer surface of the fourth electrode 400 and forms an opening on the outer periphery of the fourth electrode 400.

[0061] The second groove 410 is provided corresponding to the first sub-groove 211. That is, along the thickness direction of the cell, the projection area of ​​the first sub-groove 211 on the fourth electrode 400 at least partially overlaps with the second groove 410. It can be understood that the shape and size of the first sub-groove 211 can be consistent with the shape and size of the second groove 410, or they can be inconsistent, depending on whether they can accommodate the end of the rubber wrapping.

[0062] Based on the foregoing, such as Figure 4 As shown, the third electrode 200 has a single-sided structure. Specifically, the third electrode 200 includes a first current collector 220 and a first active material layer 230. The first active material layer 230 is disposed on the first surface 221 of the first current collector 220 near the electrode assembly 100, that is, the inner surface of the first current collector 220. The first current collector 220 also includes a second surface 222 opposite to the first surface 221. The second surface 222 is located on the side away from the electrode assembly 100, that is, the outer surface of the aforementioned third electrode 200.

[0063] It is understandable that the fourth electrode 400 is also a single-sided structure (not shown in the figure, please refer to...). Figure 4The third electrode 200 has a structure, and the fourth electrode 400 includes a second current collector and a second active material layer. The second active material layer is disposed on the third surface of the second current collector near the electrode assembly 100, which is also the inner surface of the fourth electrode 400. The fourth surface of the second current collector away from the electrode assembly 100 forms the outer surface of the fourth electrode 400.

[0064] Furthermore, the first groove 210 has an opening formed on the second surface 222, and the first groove 210 also has a bottom wall opposite to the opening. It should be noted that the first groove 210 can be processed by laser micromachining, chemical etching, mechanical micromachining, focused ion beam, and other processing techniques. It is understood that current collectors are often formed by metal roll forming, resulting in good metal flatness. The bottom wall of the first groove 210, cleaned by laser, often has poor uniformity, resulting in a rougher bottom wall than other uncleaned areas on the second surface 222. Therefore, compared to the first fixing member 310 being directly attached to the second surface 222, the rougher bottom wall of the first groove 210 is more conducive to adhesive bonding. The uneven bottom wall increases the contact area with the adhesive, thereby strengthening the bonding effect. This ensures that both the wrapping adhesive and the hot melt adhesive are firmly bonded, effectively preventing adhesive layer detachment and improving the overall stability and safety of the battery cell.

[0065] It is understandable that the bottom wall roughness of the second groove 410 of the fourth electrode 400 is also greater than the roughness of the outer surface of the fourth electrode 400.

[0066] Furthermore, the first groove 210 is disposed on the first current collector 220, and the thickness L of the first current collector 220 and the depth H of the first groove 210 have the following relationship: 0.1L≤H1≤0.75L. If the first groove 210 is too deep, it may affect the structural strength of the third electrode 200, making it prone to breakage during battery use. If the first groove 210 is too shallow, it will not significantly improve the energy density of the battery. Even further, the thickness L of the first current collector 220 and the depth H of the first groove 210 are preferably related as follows: 0.25L≤H1≤0.5L. For example, in the embodiments of this application, the aluminum foil size is 20μm, and the depth of the first groove 210 is 5μm to 10μm. Within this range, the groove depth can both ensure structural strength and significantly improve energy density.

[0067] It is understandable that the depth of the second groove 410 and the thickness of the current collector of the fourth electrode 400 can also have the above relationship, which will not be elaborated here.

[0068] In some embodiments, such as Figure 1 and Figure 4As shown, the adhesive layer typically does not cover the entire groove, but leaves a certain gap. This allows the adhesive layer to maintain some elasticity when subjected to compression deformation, preventing excessive compression from affecting the strength of the foil. Furthermore, the area occupied by the adhesive layer in the groove cannot be too small, otherwise the bonding effect will be compromised. Therefore, the area of ​​the adhesive layer and the groove have the following relationship:

[0069] 1. The projected area S1 of the first sub-fixing member 311 on the third pole piece 200 and the projected area S2 of the first sub-groove 211 on the third pole piece 200 must satisfy the following relationship: 0.55≤S1 / S2≤0.95, preferably, 0.64≤S1 / S2≤0.81;

[0070] 2. The projected area S3 of the second sub-fixing member 312 on the third pole piece 200 and the projected area S4 of the second sub-groove 212 on the third pole piece 200 must satisfy the following relationship: 0.55≤S3 / S4≤0.95, preferably, 0.64≤S3 / S4≤0.81;

[0071] 3. The projected area S5 of the third fixing member 330 on the fourth pole piece 400 and the projected area S6 of the second groove 410 on the fourth pole piece 400 must satisfy the following relationship: 0.55≤S5 / S6≤0.95, preferably, 0.64≤S5 / S6≤0.81.

[0072] In some embodiments, the first groove 210 includes a plurality of walls connected sequentially along the circumference, with an arc-shaped transition between adjacent walls. For example... Figure 1 As shown, the first groove 210 is a square groove, with rounded corners at the edges to achieve a smooth transition. This avoids stress concentration, reduces the risk of foil tearing during mechanical testing, and disperses and buffers the forces exerted during mechanical testing. It is understood that the junction of adjacent walls of the second groove 410 can also use an arc-shaped transition, which will not be elaborated upon here.

[0073] A second aspect of this application also provides a battery comprising a housing 500 and a cell as mentioned in any of the preceding embodiments, wherein, based on the foregoing, the first fixing member 310 includes a second sub-fixing member 312, and the housing 500 is connected to the third electrode 200 via the second sub-fixing member 312. It is understood that the housing 500 may be an aluminum-plastic film or other housing structure.

[0074] Furthermore, the first fixing member 310 is located in the first groove 210, and the thickness of the first fixing member 310 is greater than the depth of the first groove 210. Therefore, after the first fixing member 310 is assembled into the first groove 210, its top protrudes from the outer surface of the third electrode 200. To further improve the energy density of the battery and reduce its thickness, a fourth groove 510 is provided on the inner wall of the housing 500 corresponding to the position of the first fixing member 310, i.e., the position of the first groove 210. The fourth groove 510 is used to accommodate the first fixing member 310 protruding from the outer surface of the third electrode 200, thereby avoiding direct contact between the first fixing member 310 and the inner wall of the housing 500, reducing internal space waste, ensuring a compact battery structure, and improving overall performance.

[0075] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A battery cell, characterized in that, include: An electrode assembly, comprising a first electrode and a second electrode stacked along the thickness direction of the battery cell, wherein the first electrode and the second electrode have opposite polarities; The third electrode is disposed on one side of the electrode assembly along the thickness direction of the battery cell. The third electrode has the same polarity as the first electrode or the second electrode. The third electrode has an outer surface away from the electrode assembly, and the outer surface of the third electrode is provided with a first groove. The fastener includes a first fastener disposed in the first groove.

2. The battery cell according to claim 1, characterized in that, The fixing member further includes a second fixing member located on the side of the electrode assembly. The first fixing member includes a first sub-fixing member and a second sub-fixing member. The second fixing member is integrally connected to the first sub-fixing member, and the second sub-fixing member has a gap with the edge of the third electrode.

3. The battery cell according to claim 2, characterized in that, The first groove includes a first sub-groove for accommodating the first sub-fixing member and a second sub-groove for accommodating the second sub-fixing member.

4. The battery cell according to claim 3, characterized in that, The first sub-groove includes at least a first-level groove and a second-level groove, the first-level groove communicates with the second-level groove, and the second-level groove is located on the side of the first-level groove away from the outer surface of the third electrode; And / or, the second sub-groove includes at least a third-level groove and a fourth-level groove, the third-level groove communicating with the fourth-level groove, and the fourth-level groove being located on the side of the third-level groove away from the outer surface of the third electrode.

5. The battery cell according to claim 3, characterized in that, The battery cell also includes a fourth electrode. Along the thickness direction of the battery cell, the fourth electrode is disposed on the opposite side of the electrode assembly to the third electrode. The fourth electrode has an outer surface away from the electrode assembly. The fixing member also includes a third fixing member disposed on the outer surface of the fourth electrode. The third fixing member is integrally connected with the second fixing member.

6. The battery cell according to claim 5, characterized in that, The outer surface of the fourth electrode is provided with a second groove to accommodate the third fixing member.

7. The battery cell according to claim 6, characterized in that, Along the thickness direction of the battery cell, the first sub-groove and the second groove are respectively provided.

8. The battery cell according to claim 5, characterized in that, The fourth electrode includes a second current collector and a second active material layer, wherein the second active material layer is disposed on the inner surface of the second current collector near the electrode assembly.

9. The battery cell according to any one of claims 1 to 8, characterized in that, The third electrode includes a first current collector and a first active material layer, wherein the first active material layer is disposed on the inner surface of the first current collector near the electrode assembly.

10. The battery cell according to claim 9, characterized in that, The thickness L of the first current collector and the depth H of the first groove have the following relationship: 0.1L≤H≤0.75L.

11. The battery cell according to claim 10, characterized in that, The thickness L of the first current collector and the depth H of the first groove have the following relationship: 0.25L≤H≤0.5L.

12. The battery cell according to any one of claims 1 to 8, characterized in that, The first groove has a bottom wall that is bonded to the first fixing member, and the roughness of the bottom wall is greater than the roughness of the outer surface of the third electrode.

13. The battery cell according to claim 3, characterized in that, The projected area S1 of the first sub-fixed member and the projected area S2 of the first sub-groove have the following relationship: 0.55≤S1 / S2≤0.

95.

14. The battery cell according to claim 13, characterized in that, The projected area S1 of the first sub-fixed member and the projected area S2 of the first sub-groove have the following relationship: 0.64≤S1 / S2≤0.

81.

15. The battery cell according to claim 3, characterized in that, The projected area S3 of the second sub-fixed member and the projected area S4 of the second sub-groove have the following relationship: 0.55≤S3 / S4≤0.

95.

16. The battery cell according to claim 15, characterized in that, The projected area S3 of the second sub-fixing member and the projected area S4 of the second sub-groove have the following relationship: 0.64≤S3 / S4≤0.

81.

17. The battery cell according to claim 6, characterized in that, The projected area S5 of the third fastener and the projected area S6 of the second groove have the following relationship: 0.55≤S5 / S6≤0.

95.

18. The battery cell according to claim 17, characterized in that, The projected area S5 of the third fastener and the projected area S6 of the second groove have the following relationship: 0.64≤S5 / S6≤0.

81.

19. The battery cell according to claim 1, characterized in that, The first groove includes a plurality of walls that are connected sequentially along the circumference of the first groove, and adjacent walls are arc-shaped transitions.

20. A battery, characterized in that, The device includes a housing and a battery cell as described in any one of claims 1 to 19, wherein the first fixing member includes a second sub-fixing member, and the housing is connected to the third electrode via the second sub-fixing member.

21. The battery according to claim 20, characterized in that, The first fixing member is located in the first groove, and the thickness of the first fixing member is greater than the depth of the first groove, so that the first fixing member protrudes from the outer surface of the third electrode. Corresponding to the first groove, the inner wall surface of the housing is provided with a fourth groove, which is used to accommodate the first fixing member protruding from the outer surface of the third electrode.

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