A type of battery cell

Abstract

This utility model provides a battery cell, comprising: a housing with an opening at one end; an electrode assembly housed within the housing; and a cover plate, the edge of which is welded to the edge of the opening to seal the opening. The cover plate has a deformation guide groove recessed from one side to the other along its thickness direction. This deformation guide groove can appropriately reduce the rigidity of the cover plate, allowing it to deform in accordance with the housing, reducing the risk of weld fatigue failure and housing cracking, and improving the reliability of the battery cell.

Description

Technical Field

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

[0002] The casing of a lithium battery cell bears important functions such as mechanical protection, electrical insulation, and environmental isolation. The casing of a battery cell usually consists of a shell with an opening and a cover plate for closing the opening. The cover plate and the shell are connected together by welding. If the structural integrity of the welded area cannot be guaranteed, the safety of the battery cell cannot be guaranteed. Therefore, how to ensure the structural integrity of the casing in the welded area has become a technical problem that urgently needs to be solved in the field of modern battery technology. Summary of the Invention

[0003] This utility model provides a battery cell to solve the technical problem that the cover plate cannot undergo deformation that adapts to the shell, thus failing to guarantee the structural integrity of the cover plate edge and the welded area of ​​the shell.

[0004] This utility model provides a battery cell, the battery cell comprising: a housing, one end of which has an opening; an electrode assembly housed within the housing; a cover plate, the edge of which is welded to the edge of the opening to close the opening; and a deformation guide groove formed by recessing from one side to the other in the thickness direction of the cover plate.

[0005] In one embodiment of the present invention, the edge of the cover plate includes two long first edges arranged opposite each other along a first direction, and two short second edges arranged opposite each other along a second direction. The first direction and the second direction are perpendicular to the thickness direction of the cover plate. The deformation guide groove includes multiple straight grooves, which are parallel to the first edges.

[0006] In one embodiment of the present invention, the deformable guide groove further includes multiple arc-shaped grooves. The multiple straight grooves include a first end and a second end that are arranged opposite to each other along their length direction. The arc-shaped grooves include a first arc-shaped groove and a second arc-shaped groove. The two ends of the first arc-shaped groove and the second arc-shaped groove are tangentially connected to the first end and the second end of the two straight grooves, respectively.

[0007] Furthermore, in one embodiment of the present invention, the plurality of first arc-shaped grooves are concentric arc grooves, and the plurality of second arc-shaped grooves are concentric arc grooves.

[0008] Furthermore, in one embodiment of the present invention, in the second direction, a plurality of the linear grooves are arranged in the middle of the cover plate, the width of the cover plate in the second direction is W1, the total width of the plurality of linear grooves in the second direction is W2, W1×0.4≤W2≤W1×0.6; and / or, the distance between the edge of the linear groove closest to the first edge and the first edge is D1, 2mm≤D1≤5mm.

[0009] In one embodiment of the present invention, the cover plate has a first side and a second side that are relatively distributed along its thickness direction. The deformation guide groove includes a plurality of first grooves formed by recessing from the first side to the second side and a plurality of second grooves formed by recessing from the second side to the first side. The first grooves and the second grooves are staggered in a preset direction, which is perpendicular to the thickness direction of the cover plate.

[0010] Furthermore, in one embodiment of the present invention, in the preset direction, the minimum interval between adjacent first grooves and second grooves is D2, where 1mm≤D2≤3mm.

[0011] In one embodiment of the present invention, the thickness of the cover plate is T, the depth of the first groove in the thickness direction of the cover plate is H1, T×0.5≤H1≤T×0.65; and / or, the depth of the second groove in the thickness direction of the cover plate is H2, T×0.5≤H2≤T×0.6.

[0012] Furthermore, in one embodiment of the present invention, in the preset direction, the width of the first groove is W1, 1mm≤W1≤5mm; and / or, the width of the second groove is W2, 1mm≤W2≤5mm.

[0013] In one embodiment of the present invention, the deformation guide groove is disposed in the middle of the cover plate along the length direction of the cover plate, the electrode assembly has a dimension of L1 along the length direction of the cover plate, the stacking direction of the electrode assembly is perpendicular to the length direction of the cover plate, and the deformation guide groove has a dimension of L2 along the length direction of the cover plate, where 1 / 4 ≤ L2 / L1 ≤ 1 / 2.

[0014] Compared with the prior art, the present invention has at least the following beneficial effects:

[0015] The deformation guide groove formed by the recessed structure on the cover plate can appropriately reduce the rigidity of the cover plate. When the electrode assembly expands due to charging and discharging and temperature changes, thereby compressing the side wall of the shell and causing deformation, or when the shell is subjected to external bending deformation, the cover plate no longer rigidly resists the deformation of the shell. Instead, it compensates for this displacement through the deformation of the deformation guide groove, so that the cover plate deforms in accordance with the shell. This significantly reduces the tensile and shear stress on the connection weld between the shell and the cover plate, avoids stress concentration, and greatly reduces the risk of weld fatigue failure and shell cracking, thus improving the reliability of the battery cell. At the same time, it provides technical support for the technical solution of placing the explosion-proof valve at the bottom of the shell opposite to the cover plate. In addition, the deformation guide groove is processed by stamping or removing material from the existing cover plate, without the need for additional parts. The structure is simple, the manufacturing process is mature, the cost is controllable, and it has good engineering feasibility and economy. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0017] In the attached diagram:

[0018] Figure 1 This is a schematic diagram of the overall structure of a battery cell provided in an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of the overall structure of a battery cell provided in another embodiment of the present invention;

[0020] Figure 3 for Figure 1 Top view;

[0021] Figure 4 for Figure 3 Sectional view along the AA direction;

[0022] Figure 5 for Figure 4 A magnified view of a portion of Part B;

[0023] Figure 6 for Figure 2 Top view;

[0024] Figure 7 for Figure 6 Sectional view in the CC direction;

[0025] Figure 8for Figure 7 A magnified view of part D;

[0026] Figure 9 This is a schematic diagram of the structure of a cover plate provided in one embodiment of the present utility model;

[0027] Figure 10 This is a schematic diagram of the structure of a cover plate provided in another embodiment of the present invention;

[0028] Figure 11 A schematic diagram of the structure of a battery cell with an explosion-proof valve located at the bottom of the housing, provided for an embodiment of this utility model;

[0029] Figure 12 This is a strain cloud diagram obtained from stress simulation analysis of a cover plate without deformation guide grooves in the existing technology;

[0030] Figure 13 To Figure 9 The strain cloud diagram obtained from stress simulation analysis of the cover plate in the middle;

[0031] Figure 14 To Figure 10 The strain cloud diagram obtained from stress simulation analysis of the cover plate in the middle;

[0032] The attached figures are labeled as follows:

[0033] 100, Housing; 200, Cover plate; 210, First side; 220, Second side; 230, First edge; 240, Second edge; 300, Deformation guide groove; 310, Straight groove; 311, First end; 312, Second end; 321, First arc-shaped groove; 322, Second arc-shaped groove; 330, First groove; 340, Second groove; 400, Electrode assembly; 500, Electrode post; 600, Explosion-proof valve; X, First direction; Y, Second direction. Detailed Implementation

[0034] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0035] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0036] In the technological development of lithium batteries, to ensure the safety of individual battery cells, explosion-proof valves are typically installed on the cover plates of these cells. Currently, to reduce the impact of the explosion-proof valve opening on components such as the battery terminals and wiring harnesses, and to mitigate safety hazards associated with vehicle electrical equipment, some manufacturers place the explosion-proof valve on the bottom of the housing opposite the cover plate, preventing high-temperature, high-pressure gas from directly impacting the passenger compartment when the valve opens. However, since the cover plate no longer needs to have mounting holes for the explosion-proof valve, its rigidity is increased. Consequently, when the housing deforms due to the expansion of the electrode components or when the housing bends under external force, the cover plate cannot deform accordingly. This leads to the welded area between the cover plate edge and the housing opening being stretched and cracking. To address this issue, in recent years, technologies such as... Figure 11 The design shown involves inverting the explosion-proof valve, placing it at the bottom of the housing opposite the cover plate. This design positions the valve at the bottom of the electrode assembly housing, while the cover plate uses a flat plate structure without any explosion-proof valve opening. In the event of thermal runaway, high-temperature gases can be directionally discharged to the bottom, effectively avoiding direct impact on the passenger compartment and improving the overall vehicle safety level. However, this inverted explosion-proof valve design also presents new technical challenges. Because the cover plate is a flat plate structure, its overall rigidity is high. When the electrode assembly expands or is subjected to external pressure or bending, the cover plate does not easily adapt to deformation. This rigidity can cause excessive tensile stress on the weld joint connecting the housing and the cover plate, which can easily lead to weld fatigue or even housing cracking over time, severely affecting the structural integrity and service life of the electrode assembly. Therefore, how to effectively solve the risk of weld stress concentration and shell cracking caused by excessive rigidity of the cover plate while ensuring the safety advantages of the inverted design of the explosion-proof valve has become an urgent technical problem to be solved in this field. This utility model sets a deformation guide groove on the cover plate so that when the shell is deformed by force, the cover plate can also deform accordingly, thereby reducing the tensile stress borne by the connection weld between the shell and the cover plate, thereby ensuring the structural integrity and service life of the electrode assembly.

[0037] The technical solution of this utility model will be described in detail below with reference to specific embodiments:

[0038] Please see Figures 1-10The battery cell provided by this utility model includes a housing 100, an electrode assembly 400, and a cover plate 200. One end of the housing 100 is provided with an opening. The electrode assembly 400 is housed inside the housing 100. The edge of the cover plate 200 is welded to the edge of the opening so that the cover plate 200 closes the opening. The cover plate 200 is provided with a deformation guide groove 300 formed by recessing from one side to the other side in the thickness direction of the cover plate 200. Specifically, one or more grooves can be machined on only one side of the cover plate 200, or one or more grooves can be machined on both sides of the cover plate 200.

[0039] The above design causes the electrode assembly 400 to expand due to charging, discharging, and temperature changes, thereby compressing the sidewall of the housing 100 and causing deformation of the housing 100. The deformation guide groove 300 formed by the recessed structure on the cover plate 200 can appropriately reduce the rigidity of the cover plate 200. This means that the cover plate 200 no longer rigidly resists the deformation of the housing 100, but instead compensates for this displacement through the deformation of the deformation guide groove 300. This allows the cover plate 200 to deform in accordance with the housing 100, thus reducing the stress on the weld between the housing 100 and the cover plate 200. The tensile and shear stresses are significantly reduced, avoiding stress concentration, which greatly reduces the risk of weld fatigue failure and shell 100 cracking, improving the reliability of the battery cell. At the same time, it provides technical support for the technical solution of setting the explosion-proof valve 600 at the bottom of the shell 100 opposite to the cover plate 200. In addition, the deformation guide groove 300 is processed by stamping or removing material from the existing cover plate 200, without the need to add additional parts. The structure is simple, the manufacturing process is mature, the cost is controllable, and it has good engineering feasibility and economy.

[0040] Please see Figure 1 , Figures 3-5 , Figure 9 In an optional embodiment of the present invention, the edge of the cover plate 200 includes two first edges 230 arranged parallel to the first direction X and two second edges 240 arranged parallel to the second direction Y. The first direction X and the second direction Y are perpendicular to the thickness direction of the cover plate 200. The length of the first edge 230 is greater than the length of the second edge 240, that is, the first edge 230 is the long side of the cover plate and the second edge 240 is the short side of the cover plate 200. The deformation guide groove 300 includes multiple straight grooves 310 formed by recessing from one side to the other side in the thickness direction of the cover plate 200. The straight grooves 310 are parallel to the first edges 230. Specifically, in order to make the deformation guide groove 300 have a more uniform deformation capability, the multiple straight grooves 310 can be arranged as grooves of equal length and evenly spaced in the second direction Y, that is, in the width direction of the cover plate 200.

[0041] During charge-discharge cycles or under external pressure, the casing 100 of a battery cell is most prone to arc-shaped deformation, either bulging outward or contracting inward, in the middle section of its long side, i.e., the first edge 230. This deformation generates significant tensile or compressive stress, primarily along the second direction Y, on the rigid cover plate 200 welded to it. This results in stress concentration at the weld between the first edge 230 and the casing 100. The multiple straight grooves parallel to the first edge 230, as a whole, allow the cover plate 200 to be stretched or compressed more easily in the second direction Y, thereby precisely releasing the stress at the weld between the first edge 230 and the casing 100. This reduces the risk of cracking at the weld or at the casing 100 connected to the weld due to excessive deformation.

[0042] Please see Figure 2 , Figures 6-8 , Figure 10 In an optional embodiment of the present invention, the deformable guide groove 300 further includes multiple arc-shaped grooves formed by recesses from one side to the other along the thickness direction of the cover plate 200. The straight groove 310 includes a first end 311 and a second end 312 arranged opposite to each other along its length. The arc-shaped groove includes a first arc-shaped groove 321 and a second arc-shaped groove 322. The two ends of the first arc-shaped groove 321 and the second arc-shaped groove 322 are tangentially connected to the first end 311 and the second end 312 of the two straight grooves 310, i.e., the two ends of each pair of straight grooves 310 are symmetrically connected to the first arc-shaped groove 321 and the second arc-shaped groove 322, thereby forming a closed elongated oval structure. Specifically, the multiple elongated oval structures can be as follows: Figure 2 The series of elongated oval grooves with the same center of symmetry, which are gradually increasing in size, can also be elongated oval grooves with their centers of symmetry distributed sequentially at intervals in the second direction Y, or they can be elongated oval grooves with their centers of symmetry distributed alternately in the second direction Y.

[0043] The first end 311 and the second end 312 of the straight groove 310 are areas of high stress concentration. Under repeated deformation stress, fatigue cracks are likely to occur. The arc-shaped groove connecting the first end 311 and the second end 312 allows stress to pass smoothly through, thus preventing stress accumulation. In addition, the straight groove 310 is mainly responsible for releasing the stress of the cover plate 200 in the second direction Y, while the first arc-shaped groove 321 and the second arc-shaped groove 322 can release the stress of the cover plate 200 in the first direction X and the second direction Y. This allows the cover plate 200 to produce deformations that are compatible with the shell 100 under various working conditions, thereby further improving the structural reliability of the battery cell. Furthermore, in the first direction X, the deformation modes at both ends of the deformation guide groove 300 are completely symmetrical and balanced, avoiding uncontrollable deformations such as torsion caused by structural asymmetry of the cover plate 200.

[0044] Please see Figure 2 , Figure 6 , Figure 10 In an optional embodiment of the present invention, the multiple first arc-shaped grooves 321 are concentric arc grooves, and the multiple second arc-shaped grooves 322 are concentric arc grooves, that is, the deformation guide groove 300 is a series of elongated oval grooves with the same center of symmetry.

[0045] Compared to the oblong grooves that may intersect due to a misalignment of the center of symmetry, the above design allows stress to be evenly distributed on the overall deformation guide groove 300, thereby improving the overall fatigue resistance of the cover plate 200. Moreover, the more regular deformation guide groove 300 is easier to process and the processing error is easier to control.

[0046] Please see Figure 5 In an optional embodiment of this utility model, in the second direction Y, multiple straight grooves 310 are located in the middle of the cover plate 200 to ensure the structural symmetry of the cover plate in the second direction Y and to avoid uncontrollable torsional deformation of the cover plate in the second direction Y due to structural strength asymmetry. The width of the cover plate 200 in the second direction Y is W1, and the total width of the multiple straight grooves 310 in the second direction Y is W2. That is, in the second direction Y, the distance between the outermost edges of the two outermost straight grooves 310 is W2, W1×0.4≤W2≤W1×0.6. The lower limit of W2 can ensure that the multiple straight grooves 310 have sufficient width to release the stress of the cover plate 200, and the upper limit of W2 can ensure that the cover plate 200 still has sufficient substrate on both sides in the second direction Y to ensure the strength and sealing of the first edge 230 of the cover plate 200 after welding with the opening edge of the housing 100.

[0047] Please see Figure 5In an optional embodiment of this utility model, the distance between the edge of the straight groove 310 closest to the first edge 230 and the first edge 230 is D1, where 2mm≤D1≤5mm. The lower limit value can ensure that the first edge 230 has sufficient base material support width for the weld, thereby ensuring the mechanical strength and sealing reliability of the weld. In addition, if the distance D1 is less than 2mm, the stress generated by the groove overlaps with the thermal stress area of ​​the welding process, which may cause the material lattice in this area to change and become brittle. The upper limit value allows the deformation guide groove 300 to effectively act on the area with the greatest deformation.

[0048] Please see Figures 3-10 In one embodiment of this utility model, the cover plate 200 has a first side and a second side that are relatively distributed along its thickness direction, namely, a lower surface near the housing 100 and an upper surface away from the housing 100. The deformation guide groove 300 includes multiple first grooves 330 formed from the first side to the second side and multiple second grooves 340 formed from the second side to the first side. The first grooves 330 and the second grooves 340 are staggered in a preset direction, which is perpendicular to the thickness direction of the cover plate 200. That is, on the thickness section of the cover plate 200, an interlaced and continuous material weak surface is created. Specifically, the first grooves 330 and the second grooves 340 can all be as follows: Figures 3-5 , Figure 9 The straight groove 310 shown can also be as follows: Figures 6-8 , Figure 10 The elongated oval groove shown can be formed by adding a straight groove 310 and an arc-shaped groove on one side, or by setting an elongated oval groove on the other side.

[0049] When the cover plate 200 bends, the stress is no longer concentrated on the groove on one side, but is distributed to the grooves on both sides. This can effectively reduce the stress amplitude on the groove on one side. Because the stress is greatly reduced and distributed, the cover plate 200 suffers less damage in each deformation, thus enabling the cover plate 200 to withstand more load cycles and improve its fatigue life. The groove design that is staggered in the preset direction also avoids a sudden decrease in the stiffness of the cover plate 200 at the groove, ensuring the structural stability of the cover plate 200.

[0050] Please see Figure 5In one embodiment of this utility model, the minimum interval between adjacent first grooves 330 and second grooves 340 in a preset direction is D2, where 1mm≤D2≤3mm. When D2 is less than 1mm, the cover plate 200 may be at risk of local material tearing because the first grooves 330 and second grooves 340 are too close in the preset direction. When D2 is greater than 3mm, the first grooves 330 and second grooves 340 may be too far apart, resulting in stress not being able to be smoothly and efficiently transmitted between them. Therefore, the D2 value within the above parameter range ensures the structural strength of the cover plate 200 while taking into account the efficient deformation capability of the deformation guide groove 300.

[0051] Please see Figure 5 In one embodiment of this utility model, the thickness of the cover plate 200 is T, the depth of the first groove 330 in the thickness direction of the cover plate 200 is H1, and the depth of the second groove 340 in the thickness direction of the cover plate 200 is H2, where T×0.5≤H2≤T×0.6. In the design, H1 should satisfy T×0.5≤H1≤T×0.65, or H2 should satisfy T×0.5≤H2≤T×0.6, or T×0.5≤H1≤T×0.65 and T×0.5≤H2≤T×0.6.

[0052] By setting depths H1 and H2 to be no less than T×0.5, the first groove 330 and the second groove 340 are ensured to have sufficient depth to produce significant elastic deformation. Thus, when the shell 100 deforms, the cover plate 200 absorbs the displacement through local bending or stretching of the grooves, effectively reducing the stress at the weld. By limiting depths H1 and H2 to no more than T×0.6, most of the original thickness and section modulus of the cover plate 200 are preserved, thereby ensuring that its main body rigidity and strength as a pressure-bearing component remain intact, and it can safely and reliably bear the normal pressure inside the battery as well as the external extrusion load.

[0053] Please see Figure 5 In one embodiment of this utility model, in a preset direction, the width of the first groove 330 is W1 and the width of the second groove 340 is W2. Specifically, it can be set to 1mm≤W2≤5mm or 1mm≤W1≤5mm, or simultaneously satisfy 1mm≤W2≤5mm and 1mm≤W1≤5mm. When W1 and W2 are less than 1mm, the first groove 330 and the second groove 340 may not provide enough deformation space due to their narrow width, resulting in the stress not being effectively released. When W1 and W2 are greater than 5mm, the original rigidity of the cover plate 200 will be excessively weakened. Therefore, the width value within the above parameter range can ensure that the deformation compensation part has enough deformation space while also ensuring the working reliability of the cover plate 200.

[0054] Please see Figure 7In one embodiment of the present invention, a deformation guide groove 300 is disposed in the middle of the cover plate 200 along the length direction of the cover plate 200, the electrode assembly 400 has a dimension of L1 along the length direction of the cover plate 200, the stacking direction of the electrode assembly 400 is perpendicular to the length direction of the cover plate 200, and the deformation guide groove 300 has a dimension of L2 along the length direction of the cover plate 200, where 1 / 4≤L2 / L1≤1 / 2.

[0055] During the charging and discharging of the electrode assembly 400, expansion and deformation mainly occur along the stacking direction, and the housing 100 is also deformed by compression. This deformation is greatest in the middle of the length direction of the housing 100 and decreases towards both ends. Therefore, the deformation guide groove 300 is set in the middle of the cover plate 200 so that the cover plate 200 can better adapt to the deformation of the housing 100. Setting the ratio of the length L2 of the deformation guide groove 300 to the length L1 of the electrode assembly 400 to be greater than 1 / 4 can ensure that the deformation guide groove 300 can cover the main deformation area on the cover plate 200, thereby ensuring that the stress on the cover plate 200 can be effectively released. Setting the above length ratio to be less than 1 / 2 can ensure that the basic structural strength of the cover plate 200 is not affected by the excessively long deformation guide groove 300, and can also leave more space for installing components such as the pole post 500.

[0056] Please see Figure 12 The strain contour plot obtained from the stress simulation analysis of the cover plate 200 without the deformation guide groove 300 in the prior art shows that the maximum plastic deformation occurs on the side of the cover plate 200 connected to the weld in the middle, with a maximum equivalent plastic deformation value of 3.45%. Please refer to [link to relevant documentation]. Figure 13 The strain contour plot is obtained from the stress simulation analysis of the cover plate 200 with a deformation guide groove 300 set in the middle of its length direction. The deformation guide groove 300 is a structure with straight grooves 310 formed on both sides of the cover plate 200 along its thickness direction (see [link]). Figure 9 As can be seen from the figure, the maximum equivalent plastic deformation value is 2.44%, which is 29.3% lower than the maximum equivalent plastic deformation value without the deformation guide groove 300. Similarly, Figure 14 This is also a strain contour plot obtained from a stress simulation analysis of a cover plate 200 with a deformation guide groove 300 set in the middle of its length direction. However, in this case, the deformation guide groove 300 is a structure consisting of a straight groove 310 and an arc-shaped groove on both sides of the cover plate 200 along its thickness direction (see [link]). Figure 10 The structure is a closed elongated oval shape. As can be seen from the figure, the maximum equivalent plastic deformation value is 2.38%, which is 31% lower than the maximum equivalent plastic deformation value when the deformation guide groove 300 is not set.

[0057] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A battery cell, characterized in that, include: A housing, wherein one end of the housing is provided with an opening; An electrode assembly, wherein the electrode assembly is housed within the housing; A cover plate, the edge of which is welded to the edge of the opening to close the opening; The cover plate is provided with a deformation guide groove formed by a recess from one side to the other in the thickness direction of the cover plate.

2. The battery cell according to claim 1, characterized in that, The edge of the cover plate includes two first edges arranged parallel to a first direction and two second edges arranged parallel to a second direction. The first direction and the second direction are perpendicular to the thickness direction of the cover plate. The deformation guide groove includes multiple straight grooves. The length of the first edge is greater than the length of the second edge, and the multiple straight grooves are parallel to the first edge.

3. The battery cell according to claim 2, characterized in that, The deformation guide groove also includes multiple arc-shaped grooves. Each of the multiple straight grooves includes a first end and a second end that are arranged opposite to each other along its length. The arc-shaped groove includes a first arc-shaped groove and a second arc-shaped groove. The two ends of the first arc-shaped groove and the second arc-shaped groove are tangentially connected to the first end and the second end of the two straight grooves, respectively.

4. The battery cell according to claim 3, characterized in that, The first arc-shaped grooves are concentric arc grooves, and the second arc-shaped grooves are concentric arc grooves.

5. The battery cell according to claim 2 or 3, characterized in that, In the second direction, a plurality of the linear grooves are located in the middle of the cover plate, the width of the cover plate in the second direction is W1, the total width of the plurality of linear grooves in the second direction is W2, W1×0.4≤W2≤W1×0.6; and / or, the distance between the edge of the linear groove closest to the first edge and the first edge is D1, 2mm≤D1≤5mm.

6. The battery cell according to claim 1, characterized in that, The cover plate has a first side and a second side that are relatively distributed along its thickness direction. The deformation guide groove includes a plurality of first grooves formed by recessing from the first side to the second side and a plurality of second grooves formed by recessing from the second side to the first side. The first grooves and the second grooves are staggered in a preset direction, which is perpendicular to the thickness direction of the cover plate.

7. The battery cell according to claim 6, characterized in that, In the preset direction, the minimum interval between adjacent first and second grooves is D2, where 1mm ≤ D2 ≤ 3mm.

8. The battery cell according to claim 6, characterized in that, The thickness of the cover plate is T, the depth of the first groove in the thickness direction of the cover plate is H1, T×0.5≤H1≤T×0.65; and / or, the depth of the second groove in the thickness direction of the cover plate is H2, T×0.5≤H2≤T×0.

6.

9. The battery cell according to claim 6, characterized in that, In the preset direction, the width of the first groove is W3, 1mm≤W3≤5mm; and / or, the width of the second groove is W4, 1mm≤W4≤5mm.

10. The battery cell according to claim 1, characterized in that, Along the length of the cover plate, the deformation guide groove is located in the middle of the cover plate. The electrode assembly has a dimension of L1 along the length of the cover plate. The stacking direction of the electrode assembly is perpendicular to the length of the cover plate. The deformation guide groove has a dimension of L2 along the length of the cover plate, and 1 / 4 ≤ L2 / L1 ≤ 1 / 2.

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