Battery monomer, metal shell and electric equipment

Abstract

The invention provides a battery monomer, a metal shell and electric equipment. The battery cell comprises a shell assembly and a battery cell. The shell assembly comprises a metal shell and a cover body. The metal shell comprises a bottom plate and a side plate. The bottom plate and the side plates are enclosed to form a battery cell accommodating cavity with an opening; each side plate comprises an edge folding structure. The folding edge structure comprises more than two folding edges. And the more than two folded edges are connected in sequence. And a buffer space is formed between any two adjacent folded edges. And one folding edge adjacent to the cover body is connected with the cover body. And the cover body covers the battery cell accommodating cavity. The battery cell is arranged in the battery cell accommodating cavity; according to the battery monomer, the possibility of electrolyte leakage of the battery monomer can be reduced.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular to a battery cell, a metal shell and an electrical device. Background Art

[0002] Battery cells refer to products that can be used continuously by recharging the active materials after the battery core is discharged. Battery cells are widely used in electrical devices such as mobile phones, laptops, power tools, vehicles, etc. In the development of battery technology, how to ensure the safety of battery cells is one of the research directions in battery technology. Summary of the invention

[0003] In view of the above problems, the present application provides a battery cell, a metal shell and an electrical device, which can reduce the possibility of electrolyte leakage in the battery cell.

[0004] The present application provides a battery cell, which includes a shell assembly and a battery cell. The shell assembly includes a metal shell and a cover body. The metal shell includes a bottom plate and a side plate. The bottom plate and the side plate enclose a battery cell accommodating cavity with an opening. The side plate includes a folding edge structure. The folding edge structure includes more than two folding edges. The more than two folding edges are connected in sequence. A buffer space is formed between any two adjacent folding edges. A folding edge adjacent to the cover body is connected to the cover body. The cover body covers the battery cell accommodating cavity. The battery cell is arranged in the battery cell accommodating cavity.

[0005] When the battery cell of the embodiment of the present application is subjected to an impact force so that the battery cell moves relative to the shell assembly, when the battery cell impacts the metal shell, the area of ​​the folding structure on the side panel that is subjected to the impact can first be deformed by force and expanded outward, so that the folding structure can unfold. The folding structure can effectively absorb the impact force of the battery cell during the unfolding process, thereby effectively reducing the impact force that the metal shell and the cover connection area need to bear. Therefore, the battery cell of the embodiment of the present application can effectively absorb the impact energy of the battery cell through the folding structure, reduce the load borne by the metal shell and the cover connection area, thereby reducing the possibility of separation of the metal shell and the cover connection area, and reducing the possibility of electrolyte leakage in the battery cell. The battery cell of the embodiment of the present application does not need to increase the thickness of the metal shell or increase the size of the metal shell and the cover in the connection area, which is conducive to ensuring that the battery cell has a relatively high energy density.

[0006] In some practicable embodiments, the folded edge includes a connected straight portion and a curved portion, and the straight portion of one folded edge is connected to the curved portion of another adjacent folded edge.

[0007] The curved portion itself has a smooth transition, and a smooth transition can be achieved between the curved portion and the straight portion, so that internal stress is not easily accumulated inside the curved portion itself, and internal stress is not easily accumulated at the junction between the curved portion and the straight portion, which is beneficial to avoid introducing local stress failure points or microcracks on the folded edge, and is beneficial to reducing the possibility of local fracture failure of the folded edge.

[0008] When the battery cell impacts the folded edge structure, the battery cell can contact the bent portion. The force on the bent portion itself is balanced, so the bent portion can be used to guide the folded edge to deform. At the same time, during the unfolding process of the folded edge, the bent portion can always maintain a smooth transition state, effectively avoiding the occurrence of sharp folding structures in the bent portion, thereby helping to reduce the possibility of local fracture failure of the folded edge due to the sharp folding structure of the folded edge.

[0009] When the battery cell impacts the folded edge structure, the battery cell can contact the bent portion. The bent portion itself has a smooth transition, so the bent portion will not apply local concentrated stress to the battery cell, reducing the possibility of the positive and negative plates being short-circuited due to local extrusion of the battery cell, thereby improving the safety of the battery cell.

[0010] In some achievable ways, the curved portion is arc-shaped. The curved portion itself has a smooth transition, and a smooth transition can be achieved between the curved portion and the straight portion, so that internal stress is not easily accumulated inside the curved portion itself. The two ends of the curved portion are respectively connected to the two straight portions. The arc-shaped curved portion is relatively easy to process and manufacture, which is conducive to reducing the processing difficulty of the curved portion itself, and further conducive to reducing the processing difficulty of the overall folding structure.

[0011] In some achievable embodiments, the opening size of the buffer space is larger than the opening size of the bent portion. When the battery cell exerts an impact force on the folded edge structure, the two straight portions connected by a bent portion are easily deformed outward to increase the opening of the buffer space, thereby facilitating the smooth outward expansion and deformation of the folded edge structure and reducing the difficulty of the outward expansion of the folded edge structure.

[0012] In some achievable embodiments, the metal shell and the cover are stacked in the thickness direction of the cover, and the size of the folded edge structure in the thickness direction of the cover is less than or equal to the size of the battery cell. The size of the side plate can be reasonably designed to reduce the possibility of increasing the overall volume of the battery cell due to the increase in the size of the folded edge structure in the thickness direction of the cover, thereby facilitating the battery cell to have a relatively high energy density.

[0013] In some achievable methods, the folded edge does not exceed the edge of the cover in the direction perpendicular to the thickness direction of the cover. The maximum size of the cover in the direction perpendicular to the thickness direction of the cover is the maximum size of the battery cell as a whole. Therefore, the method in which the folded edge does not exceed the edge of the cover will not increase the size of the battery cell in the direction perpendicular to the thickness direction of the cover, which is conducive to ensuring that the battery cell has a relatively high energy density.

[0014] In some achievable embodiments, the number of hems is an even number. The free end of the hem structure is located inside the shell assembly. The free end of the hem structure is not easily observed from the outside of the battery cell. When the hem structure is deformed outward by the impact of the battery cell, the hem is first subjected to force and unfolded. After the hem is unfolded to a predetermined degree, under the pulling action of the hem, the connection area between the hem and the cover body mainly bears shear force, while the peeling force borne by the connection area is relatively small. Shear force refers to the force perpendicular to the thickness direction of the cover body. Peeling force refers to the force in the same direction as the thickness direction of the cover body. Since the shear force resistance between the connection area of ​​the hem and the cover body is greater than the peeling force resistance between the connection area of ​​the hem and the cover body, the connection area of ​​the hem and the cover body is not easy to crack and fail under the action of shear force, thereby ensuring that after the hem structure is deformed outward, the connection area of ​​the hem and the cover body is not easy to crack, thereby improving the safety of the battery cell.

[0015] In some achievable embodiments, the number of folded edges is an odd number. The free end of the folded edge structure is located outside the shell assembly. The free end of the folded edge structure can be observed from the outside of the battery cell. When the folded edge structure is impacted by the battery cell, the battery cell will not contact the free end of the folded edge structure, so that the free end of the folded edge structure will not impact, squeeze the battery cell and apply local concentrated stress to the battery cell, thereby reducing the possibility of short circuit between the positive and negative electrodes due to local squeezing of the battery cell, and improving the safety of the battery cell.

[0016] In some achievable embodiments, the hem comprises a first straight portion and a second straight portion connected to each other, the first straight portion and the second straight portion are arranged to intersect, and the first straight portion of one hem is connected to the second straight portion of another adjacent hem.

[0017] The first straight portion and the second straight portion are relatively easy to process and manufacture, which is helpful to reduce the processing difficulty of the folding edge itself, and further helps to reduce the processing difficulty of the folding edge structure as a whole.

[0018] In some achievable embodiments, the angle between the tangent line of the curved portion at the connection point with the straight portion and the straight portion is greater than 90° and less than 180°. Internal stress is not easily accumulated at the junction between the curved portion and the straight portion, thereby facilitating the avoidance of introducing local stress failure points or microcracks on the folded edge, and facilitating the reduction of the possibility of local fracture failure of the folded edge.

[0019] In some achievable embodiments, the angle between the first straight portion and the second straight portion is greater than or equal to 80° and less than or equal to 100°. The junction between the first straight portion and the second straight portion is not prone to internal stress accumulation, thereby facilitating the avoidance of introducing local stress failure points or microcracks on the folded edge, and facilitating the reduction of the possibility of local fracture failure of the folded edge.

[0020] In some feasible embodiments, a folded edge adjacent to the cover body is welded to the cover body to form a weld. When the folded edge structure is impacted by the battery cell, the folded edge structure can effectively absorb the impact energy after deformation, so as to effectively reduce the force borne by the weld. The shear force resistance of the weld itself is greater than the peeling force resistance. When the folded edge structure is impacted by the battery cell, the folded edge structure is deformed, and under the pulling action of the folded edge structure, the weld can mainly bear the shear force. Therefore, the welding area of ​​the folded edge and the cover body is not easy to crack and fail under the action of shear force, thereby ensuring that after the folded edge structure expands outward and deforms, the welding area of ​​the folded edge and the cover body is not easy to crack, thereby improving the safety of battery cells.

[0021] In addition, the welding process used between the metal shell and the cover body can make the connection between the metal shell and the cover body less difficult and easy to connect, while effectively ensuring the sealing between the metal shell and the cover body.

[0022] In some achievable embodiments, in a direction perpendicular to the thickness direction of the cover body, the width of the weld is in a range of 0.05 mm to 0.3 mm.

[0023] If the width of the weld is less than 0.05 mm, the shear resistance of the weld is not enough to resist the impact of the battery cell, which will still cause the weld to crack and fail. If the width of the weld is greater than 0.3 mm, the width of the weld is relatively too wide. In order to adapt to the wider weld, the width of the fold needs to be increased, which will increase the overall volume of the battery cell and reduce the energy density of the battery cell.

[0024] In some achievable embodiments, the battery cell includes a pole, the metal shell includes four side plates, at least one side plate includes a folded edge structure, one side plate is provided with a pole, and the pole is electrically connected to the battery cell. The space of the metal shell can be reused to provide the pole, so as to improve the utilization rate of the metal shell, and at the same time, it is beneficial to improve the structural compactness of the battery cell.

[0025] The embodiment of the present application provides a metal shell for a battery cell. The metal shell includes a bottom plate and a side plate. The side plate is connected to the bottom plate. The bottom plate and the side plate enclose a battery cell accommodating cavity with an opening. The side plate includes a folding edge structure. The folding edge structure includes more than two folding edges. The more than two folding edges are connected in sequence. A buffer space is formed between any two adjacent folding edges.

[0026] An embodiment of the present application provides an electrical device, which includes a battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Also, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0028] Figure 1 It is a structural schematic diagram of a battery cell provided by the related technology;

[0029] Figure 2 It is a schematic diagram of a partial cross-sectional structure of a battery cell provided by the related technology;

[0030] Figure 3 is a schematic structural diagram of a battery cell provided by an embodiment of the present application;

[0031] Figure 4 is a schematic diagram of a partial cross-sectional structure of a battery cell provided in one embodiment of the present application;

[0032] Figure 5 is a schematic diagram of a partial cross-sectional structure of a battery cell provided in one embodiment of the present application;

[0033] Figure 6 is a schematic diagram of a partial cross-sectional structure of a battery cell provided in one embodiment of the present application;

[0034] Figure 7 It is a partial cross-sectional structural schematic diagram of a folding structure provided by an embodiment of the present application;

[0035] Figure 8 is a schematic diagram of a partial cross-sectional structure of a battery cell provided in one embodiment of the present application;

[0036] Fig. 9 It is a schematic diagram of a partial cross-sectional structure of a folded edge provided in an embodiment of the present application;

[0037] Fig.10 is a schematic diagram of a partial cross-sectional structure of a battery cell provided in one embodiment of the present application;

[0038] Fig.11 It is a partial cross-sectional structural schematic diagram of a folding structure provided by an embodiment of the present application;

[0039] Fig.12 is a schematic diagram of a partial cross-sectional structure of a battery cell provided in one embodiment of the present application;

[0040] Fig.13is a schematic diagram of a partial cross-sectional structure of a battery cell provided in one embodiment of the present application;

[0041] Fig.14 is a schematic diagram of a partial cross-sectional structure of a battery cell provided in one embodiment of the present application;

[0042] Fig.15 It is a schematic diagram of a partial cross-sectional structure of a battery cell provided by the related technology.

[0043] Description of reference numerals:

[0044] 10. Battery cells;

[0045] 20. Shell assembly;

[0046] 30. Battery cells;

[0047] 40. metal shell; 401. battery cell accommodating chamber;

[0048] 41. Bottom plate;

[0049] 42. Side panels;

[0050] 43. Folding structure; 431. Free end;

[0051] 44, folded edge; 44a, first straight portion; 44b, second straight portion; 441, straight portion; 442, curved portion;

[0052] 45. Buffer space;

[0053] 50. Cover body;

[0054] 60. Pole;

[0055] 70. Welding seam;

[0056] 100, Flanging;

[0057] Z, thickness direction. DETAILED DESCRIPTION

[0058] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0059] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in the embodiments of the present application should have the common meanings understood by technicians in the field to which the embodiments of the present application belong.

[0060] In the description of the embodiments of the present application, the orientation or positional relationship indicated by the technical terms "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. is based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the embodiments of the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application. It should be noted that there are tolerances in the manufacturing process, and there may be tolerances in the verticality or parallelism, and the tolerance range is ±10°.

[0061] In addition, the technical terms "first", "second", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0062] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0063] In the related technology, Figure 1 The structure of the battery cell 10 is schematically shown. Figure 2 The partial cross-sectional structure of the battery cell 10 is schematically shown. Figure 1 and Figure 2As shown, the battery cell 10 includes a shell assembly 20 and a battery cell 30 disposed in the shell assembly 20. The shell assembly 20 includes a metal shell 40 and a cover 50 connected to each other. The metal shell 40 of the shell assembly 20 includes a flange 100. The flange 100 of the metal shell 40 is connected to the cover 50. When the device including the battery cell 10 encounters a fall or repeated vibration during use, the battery cell 10 will also be subjected to impact force, so that the battery cell 30 moves relative to the metal shell 40 and impacts the metal shell 40. Under the impact of the battery cell 30, the area of ​​the metal shell 40 that is impacted will expand and deform outward, so that the metal shell 40 and the cover 50 bear a large peeling force in the connection area, so that the metal shell 40 and the cover 50 are separated in the connection area and cause electrolyte leakage, affecting the safety and reliability of the battery cell 10. In order to solve the above problems, the thickness of the metal shell 40 can be thickened to improve the anti-impact deformation ability of the metal shell 40 itself, and reduce the deformation of the metal shell 40 itself under the impact of the battery cell 30. Alternatively, the size of the metal shell 40 and the cover 50 in the connection area is increased to increase the force transmission path, thereby helping to reduce the force borne by the connection area. However, the above structural designs will lead to an increase in the overall volume of the battery cell 10, thereby causing the energy density of the battery cell 10 to decrease. Energy density refers to the ratio between the discharge energy of the battery cell 10 and the volume of the battery cell 10.

[0064] The battery cell 10 of the embodiment of the present application can effectively reduce the possibility of separation between the metal shell 40 and the cover 50 in the connection area, reduce the possibility of electrolyte leakage in the battery cell 10, and ensure that the battery cell 10 has a relatively high energy density.

[0065] Figure 3 The structure of the battery cell 10 is schematically shown. Figure 4 The partial cross-sectional structure of the battery cell 10 is schematically shown. Figure 3 and Figure 4 As shown, the battery cell 10 of the embodiment of the present application includes a shell assembly 20 and a battery cell 30. The battery cell 30 is disposed in the shell assembly 20.

[0066] The shell assembly 20 of the embodiment of the present application includes a metal shell 40 and a cover body 50. The metal shell 40 includes a bottom plate 41 and a side plate 42 connected to each other. The bottom plate 41 and the side plate 42 enclose a battery cell accommodating cavity 401 with an opening. The side plate 42 includes a folding structure 43. The folding structure 43 includes more than two folding edges 44. The more than two folding edges 44 are connected in sequence. A buffer space 45 is formed between any two adjacent folding edges 44. A folding edge 44 adjacent to the cover body 50 in the folding structure 43 is connected to the cover body 50. The cover body 50 covers the battery cell accommodating cavity 401. The battery cell 30 is arranged in the battery cell accommodating cavity 401. The battery cell 30 can be loaded into the metal shell 40 through the opening of the battery cell accommodating cavity 401.

[0067] The metal shell 40 of the embodiment of the present application can be connected to the cover 50 through the folding structure 43 on the side plate 42. Along the depth direction of the battery cell accommodating cavity 401, the folding edges 44 in the folding structure 43 are connected in sequence. Figure 4 As shown, the folded edge structure 43 on the side plate 42 of the embodiment of the present application can be in a wrinkled state. The folded edge structure 43 has the ability to deform under force. Figure 5 The partial cross-sectional structure of the battery cell 10 is schematically shown. Figure 5 FIG. 4 illustrates a structure in which the side plate 42 is deformed by the impact of the battery cell 30. Figure 5 As shown, the area on the folded edge structure 43 that is subjected to the impact force can be deformed from the folded state to the unfolded state. Of any two adjacent buffer spaces 45 in the folded edge structure 43, one buffer space 45 is located inside the metal shell 40 and is connected to the battery cell accommodating cavity 401, and the other buffer space 45 is located outside the metal shell 40 and is not connected to the battery cell accommodating cavity 401. Any two adjacent buffer spaces 45 are not connected.

[0068] When the battery cell 10 of the embodiment of the present application is subjected to an impact force so that the battery cell 30 moves relative to the shell assembly 20, when the battery cell 30 impacts the metal shell 40, the area of ​​the folding structure 43 on the side plate 42 subjected to the impact can be first deformed by force to expand outward, so that the folding structure 43 is unfolded. During the unfolding process of the folding structure 43, the impact force of the battery cell 30 can be effectively absorbed, thereby effectively reducing the impact force that needs to be borne by the connection area of ​​the metal shell 40 and the cover 50. Therefore, the battery cell 10 of the embodiment of the present application can effectively absorb the impact energy of the battery cell 30 through the folding structure 43, reduce the load borne by the connection area of ​​the metal shell 40 and the cover 50, thereby reducing the possibility of separation of the connection area of ​​the metal shell 40 and the cover 50, and reducing the possibility of electrolyte leakage in the battery cell 10. The battery cell 10 of the embodiment of the present application does not need to increase the thickness of the metal shell 40 or increase the size of the metal shell 40 and the cover 50 in the connection area, which is conducive to ensuring that the battery cell 10 has a relatively high energy density.

[0069] In some practicable embodiments, the material of the metal housing 40 may include but is not limited to steel, stainless steel, aluminum or aluminum alloy. The material of the cover 50 may include but is not limited to steel, stainless steel, aluminum or aluminum alloy.

[0070] In some practicable embodiments, the bottom plate 41 and the side plate 42 may be an integrally formed structure, which is beneficial for improving the connection strength between the bottom plate 41 and the side plate 42 .

[0071] In some possible implementations, see Figure 3 As shown, the battery cell 10 further includes a pole 60. The pole 60 may be disposed on the side plate 42 of the metal shell 40. The pole 60 is electrically connected to the battery cell 30. The battery cell 30 may be charged or discharged through the pole 60.

[0072] In some achievable ways, Figure 6 The partial cross-sectional structure of the battery cell 10 is schematically shown. Figure 7 The partial cross-sectional structure of the folding structure 43 is schematically shown. Figure 6 and Figure 7 As shown, each hem 44 in the hem structure 43 includes a first straight portion 44a and a second straight portion 44b connected to each other. The first straight portion 44a and the second straight portion 44b are arranged to intersect. There is an angle between the first straight portion 44a and the second straight portion 44b. The first straight portion 44a of a hem 44 can be connected to the second straight portion 44b of another adjacent hem 44. The first straight portion 44a and the second straight portion 44b are relatively easy to manufacture, which is conducive to reducing the difficulty of manufacturing the hem 44 itself, and then is conducive to reducing the difficulty of manufacturing the hem structure 43 as a whole.

[0073] In some examples, the angle K between the first straight portion 44a and the second straight portion 44b is greater than or equal to 80° and less than or equal to 100°. The junction between the first straight portion 44a and the second straight portion 44b is not easy to accumulate internal stress, which is conducive to avoiding the introduction of local stress failure points or microcracks on the folded edge 44, and is conducive to reducing the possibility of local fracture failure of the folded edge 44. In some examples, see Figure 7 As shown, the first straight portion 44a and the second straight portion 44b can be perpendicular to each other. The angle K between the first straight portion 44a and the second straight portion 44b is 90°. The rounded transition between the first straight portion 44a and the second straight portion 44b reduces the possibility of stress concentration in the transition area between the first straight portion 44a and the second straight portion 44b.

[0074] In some achievable ways, Figure 8 The partial cross-sectional structure of the battery cell 10 is schematically shown. Fig. 9 The partial cross-sectional structure of the folded edge 44 is schematically shown. Figure 8 and Fig. 9 As shown, the folded edge 44 includes a connected straight portion 441 and a curved portion 442. In any two adjacent folded edges 44, the straight portion 441 of one folded edge 44 is connected to the curved portion 442 of another adjacent folded edge 44. In the overall structure of the folded edge structure 43, the curved portion 442 and the straight portion 441 are alternately arranged in sequence.

[0075] The curved portion 442 itself has a smooth transition, and a smooth transition can be achieved between the curved portion 442 and the straight portion 441, so that internal stress is not easily accumulated inside the curved portion 442 itself, and internal stress is not easily accumulated at the junction between the curved portion 442 and the straight portion 441, which is beneficial to avoid introducing local stress failure points or microcracks on the folded edge 44, and is beneficial to reducing the possibility of local fracture failure of the folded edge 44.

[0076] When the battery cell 30 impacts the folded edge structure 43, the battery cell 30 may contact the bent portion 442. The bent portion 442 itself is force-balanced, so that the bent portion 442 can be used to guide the folded edge 44 to deform. At the same time, during the unfolding process of the folded edge 44, the bent portion 442 can always maintain a smooth transition state, effectively avoiding the occurrence of a sharp folding structure in the bent portion 442, thereby helping to reduce the possibility of local fracture failure of the folded edge 44 due to the sharp folding structure of the folded edge 44.

[0077] When the battery cell 30 impacts the folded edge structure 43, the battery cell 30 can contact the curved portion 442. The curved portion 442 itself has a smooth transition, so that the curved portion 442 does not apply local concentrated stress to the battery cell 30, reducing the possibility of the positive and negative electrodes being short-circuited due to local compression of the battery cell 30, thereby improving the safety of the battery cell 10.

[0078] For some examples, see Fig. 9 As shown, the angle K between the tangent of the curved portion 442 at the connection point with the straight portion 441 and the straight portion 441 is an obtuse angle greater than 90°. Exemplarily, the angle K between the tangent of the curved portion 442 at the connection point with the straight portion 441 and the straight portion 441 is greater than 90° and less than 180°. The junction between the curved portion 442 and the straight portion 441 is not easy to accumulate internal stress, which is conducive to avoiding the introduction of local stress failure points or microcracks on the folded edge 44, and is conducive to reducing the possibility of local fracture failure of the folded edge 44. Exemplarily, the angle K between the tangent of the curved portion 442 at the connection point with the straight portion 441 and the straight portion 441 can be 120° or 140°.

[0079] In some examples, there is a spacing between any two adjacent straight portions 441 in the hem structure 43, that is, there is no contact between any two adjacent straight portions 441. The straight portion 441 of a hem 44 adjacent to the cover 50 in the hem structure 43 is connected to the cover 50. The straight portion 441 is relatively flat and has a relatively large area, which facilitates the connection operation between the hem 44 and the cover 50 and reduces the difficulty of connection.

[0080] In some examples, the curved portion 442 of the folded edge 44 is arc-shaped. The curved portion 442 itself has a smooth transition, and a smooth transition can be achieved between the curved portion 442 and the straight portion 441, so that the curved portion 442 itself is not easy to accumulate internal stress. The two ends of the curved portion 442 are respectively connected to the two straight portions 441. The curved curved portion 442 is relatively easy to process and manufacture, which is conducive to reducing the processing difficulty of the curved portion 442 itself, and then it is conducive to reducing the processing difficulty of the folded edge structure 43 as a whole. Exemplarily, the curved portion 442 of the folded edge 44 is an elliptical arc or a circular arc.

[0081] In some examples, Fig.10 The partial cross-sectional structure of the battery cell 10 is schematically shown. Fig.11 The partial cross-sectional structure of the folding structure 43 is schematically shown. Fig.10 and Fig.11 As shown, the opening size of the buffer space 45 is larger than the opening size of the curved portion 442. The opening size of the buffer space 45 is the size value measured along the thickness direction Z of the cover body 50. The opening size of the curved portion 442 is the size value measured along the thickness direction Z of the cover body 50. The cross-sectional area of ​​the buffer space 45 increases in the direction away from the curved portion 442. In the two straight portions 441 connected by a curved portion 442, the spacing between the edges of the two straight portions 441 away from the curved portion 442 is a first spacing D1, and the spacing between the edges of the two straight portions 441 close to the curved portion 442 is a second spacing D2, wherein the first spacing D1 is larger than the second spacing D2. The two straight portions 441 connected by a curved portion 442 are not parallel to each other. The opening size of the curved portion 442 may be equal to the first spacing D1.

[0082] When the battery cell 30 exerts impact force on the folded edge structure 43, the two straight portions 441 connected by a curved portion 442 are easily deformed outward to increase the opening of the buffer space 45, thereby facilitating the folded edge structure 43 to expand and deform outward smoothly and reducing the difficulty of the folded edge structure 43 expanding outward.

[0083] In some examples, the straight portions 441 in the folding structure 43 are arranged parallel to each other. For two straight portions 441 connected by a curved portion 442, the spacing between the edges of the two straight portions 441 away from the curved portion 442 is a first spacing D1, and the spacing between the edges of the two straight portions 441 close to the curved portion 442 is a second spacing D2, wherein the first spacing D1 is equal to the second spacing D2. Along the thickness direction Z of the cover body 50, the straight portions 441 are spaced apart. Exemplarily, the thickness direction Z of the cover body 50 may be the same as the depth direction of the battery cell accommodating cavity 401. The straight portions 441 may be distributed at equal intervals or at unequal intervals. Exemplarily, the straight portions 441 in the folding structure 43 may have the same size and structure.

[0084] In some achievable embodiments, the metal shell 40 and the cover 50 are stacked along the thickness direction Z of the cover 50. Along the thickness direction Z of the cover 50, the size of the folded edge structure 43 is less than or equal to the size of the battery cell 30, so that the size of the side plate 42 can be reasonably designed, reducing the possibility of increasing the overall volume of the battery cell 10 due to the increase in the size of the folded edge structure 43 in the thickness direction Z of the cover 50, thereby facilitating ensuring that the battery cell 10 has a relatively high energy density.

[0085] In some examples, the metal shell 40 and the cover 50 are stacked along the thickness direction Z of the cover 50. The thickness direction Z of the cover 50 is the same as the thickness direction of the battery cell 30. Along the thickness direction of the battery cell 30, the size of the folded edge structure 43 is less than or equal to the thickness of the battery cell 30.

[0086] In some achievable ways, the folded edge 44 in the folded edge structure 43 does not exceed the edge of the cover 50. Along the thickness direction Z of the cover 50, the orthographic projection of the folded edge structure 43 does not exceed the outer contour of the orthographic projection of the cover 50. In the direction perpendicular to the thickness direction Z of the cover 50, the maximum size of the cover 50 is the maximum size of the entire battery cell 10. Therefore, the way in which the folded edge 44 does not exceed the edge of the cover 50 will not increase the size of the battery cell 10 in the direction perpendicular to the thickness direction Z of the cover 50, which is conducive to ensuring that the battery cell 10 has a relatively high energy density.

[0087] In some achievable ways, Fig.12 The partial cross-sectional structure of the battery cell 10 is schematically shown. Fig.12 As shown, the number of the folded edges 44 may be an even number. The opening of the first buffer space 45 in the folded edge structure 43 close to the cover body 50 faces the battery cell accommodating cavity 401. The first buffer space 45 in the folded edge structure 43 close to the cover body 50 is connected to the battery cell accommodating cavity 401.

[0088] The free end 431 of the folding structure 43 is located inside the shell assembly 20. The free end 431 of the folding structure 43 is not easily observed from the outside of the battery cell 10. When the folding structure 43 is deformed by the impact of the battery cell 30 and expands outward, the folding edge 44 is first forced to unfold. After the folding edge 44 is unfolded to a predetermined extent, under the pulling action of the folding edge 44, the connection area between the folding edge 44 and the cover body 50 mainly bears shear force, while the peeling force borne by the connection area is relatively small. Shear force refers to the force perpendicular to the thickness direction Z of the cover body 50. Peeling force refers to the force in the same thickness direction Z of the cover body 50. Since the shear resistance performance between the connection area of ​​the folded edge 44 and the cover body 50 is greater than the peel resistance performance between the connection area of ​​the folded edge 44 and the cover body 50, the connection area of ​​the folded edge 44 and the cover body 50 is not easy to crack and fail under the action of shear force, thereby ensuring that after the folded edge structure 43 expands and deforms outward, the connection area of ​​the folded edge 44 and the cover body 50 is not easy to crack, thereby improving the safety of the battery cell 10.

[0089] In some examples, the number of folded edges 44 may be an even number. The straight portion 441 on the folded edge structure 43 connected to the cover 50 may be located inside the shell assembly 20. The straight portion 441 connected to the cover 50 is not easily observed from the outside of the battery cell 10. The free end of the straight portion 441 connected to the cover 50 is disposed facing the battery cell 30. The free end of the straight portion 441 connected to the cover 50 is the free end 431 of the folded edge structure 43.

[0090] In some achievable ways, Fig.13 The partial cross-sectional structure of the battery cell 10 is schematically shown. Fig.13 As shown, the number of the folded edges 44 can be an odd number. The opening of the first buffer space 45 near the cover 50 in the folded edge structure 43 faces away from the battery cell accommodating cavity 401. The first buffer space 45 near the cover 50 in the folded edge structure 43 is not connected to the battery cell accommodating cavity 401.

[0091] The free end 431 of the folded edge structure 43 is located outside the shell assembly 20. The free end 431 of the folded edge structure 43 can be observed from the outside of the battery cell 10. When the folded edge structure 43 is impacted by the battery cell 30, the battery cell 30 will not contact the free end 431 of the folded edge structure 43, so that the free end 431 of the folded edge structure 43 will not impact, squeeze the battery cell 30 and apply local concentrated stress to the battery cell 30, thereby reducing the possibility of short circuit between the positive and negative electrodes due to local squeezing of the battery cell 30, and improving the safety of the battery cell 10.

[0092] In some examples, the number of folded edges 44 may be an odd number. The straight portion 441 on the folded edge structure 43 connected to the cover 50 is located outside the shell assembly 20, and the straight portion 441 connected to the cover 50 can be observed from the outside of the battery cell 10. The free end of the straight portion 441 connected to the cover 50 is arranged away from the battery cell 30. The free end of the straight portion 441 connected to the cover 50 is located outside the shell assembly 20.

[0093] In some achievable embodiments, the hem structure 43 may include two hems 44, three hems 44, four hems 44, or five hems 44. In some examples, Fig.14 The partial cross-sectional structure of the battery cell 10 is schematically shown. Fig.14 As shown, the folding structure 43 may include two folding edges 44. The opening of the buffer space 45 formed by the two folding edges 44 faces the battery cell accommodating cavity 401. The buffer space 45 formed by the two folding edges 44 is connected to the battery cell accommodating cavity 401. The free end of the straight portion 441 connected to the cover body 50 is arranged facing the battery cell 30. Under the condition of ensuring that the folding structure 43 effectively reduces the stress in the connection area through deformation buffering, the overall processing procedure of the folding structure 43 is relatively simple, and the folding structure 43 can be formed by bending the side plate 42 less times.

[0094] In some possible implementations, see Fig.14 As shown, a folded edge 44 adjacent to the cover body 50 in the folded edge structure 43 is welded to the cover body 50 to form a weld 70. The welding area between the folded edge 44 and the cover body 50 is the connection area between the metal shell 40 and the cover body 50.

[0095] When the folding structure 43 is impacted by the battery cell 30, the folding structure 43 can effectively absorb the impact energy after being deformed, so as to effectively reduce the force borne by the weld 70. The shear force resistance performance of the weld 70 itself is greater than the peeling force resistance performance. When the folding structure 43 is impacted by the battery cell 30, the folding structure 43 is deformed, and under the pulling action of the folding structure 43, the weld 70 can mainly bear the shear force. Therefore, the welding area between the folding edge 44 and the cover body 50 is not easy to crack and fail under the action of shear force, thereby ensuring that after the folding structure 43 is deformed by expanding outward, the welding area between the folding edge 44 and the cover body 50 is not easy to crack, thereby improving the safety of the battery cell 10.

[0096] In addition, the welding process used between the metal shell 40 and the cover body 50 can reduce the difficulty of connecting the metal shell 40 and the cover body 50, facilitate the connection operation of the metal shell 40 and the cover body 50, and effectively ensure the sealing between the metal shell 40 and the cover body 50.

[0097] In some achievable embodiments, in a direction perpendicular to the thickness direction Z of the cover body 50, the width of the weld 70 ranges from 0.05 millimeters (mm) to 0.3 millimeters. The shear resistance of the weld 70 is proportional to the width of the weld 70. If the width of the weld 70 is less than 0.05 mm, the shear resistance of the weld 70 is not sufficient to resist the impact force of the battery cell 30 well, and the weld 70 will still crack and fail. If the width of the weld 70 is greater than 0.3 mm, the width of the weld 70 is relatively too wide. In order to adapt to the wider weld 70, the width of the folded edge 44 needs to be increased, which increases the overall volume of the battery cell 10 and reduces the energy density of the battery cell 10.

[0098] In some examples, the width of the weld 70 is 0.1 mm, so that the weld 70 not only meets the requirement of not being prone to cracking failure due to impact, but also does not reduce the energy density of the battery cell 10 due to its wider width.

[0099] In some achievable embodiments, the cover 50 may be a plate-shaped structure. The surface of the cover 50 facing the battery cell 30 may be a flat surface, so that when the battery cell 30 contacts the cover 50, the cover 50 will not apply local concentrated stress to the battery cell 30, which is conducive to reducing the possibility of the cover 50 applying local concentrated stress to the battery cell 30 when the battery cell 30 impacts the cover 50, thereby improving the safety of the battery cell 30.

[0100] In some achievable embodiments, the battery cell 10 includes a pole 60. The metal shell 40 includes four side plates 42. At least one side plate 42 includes a folding structure 43. A pole 60 is provided on one side plate 42. The pole 60 is electrically connected to the battery cell 30. The pole 60 can be provided in the space of the metal shell 40 to improve the utilization rate of the metal shell 40, and at the same time, it is beneficial to improve the structural compactness of the battery cell 10.

[0101] In some examples, three side panels 42 include folding structures 43, and another side panel 42 is not provided with folding structures 43. The pole 60 is provided on the side panel 42 without folding structures 43, thereby reducing the possibility of positional interference between the folding structures 43 and the pole 60, which is conducive to reasonably setting the position of the pole 60.

[0102] In some examples, the four side panels 42 include a folded edge structure 43 , so that when the battery cell 30 moves toward any side panel 42 and impacts the corresponding side panel 42 , the metal shell 40 can buffer the impact force of the battery cell 30 and improve the overall impact resistance of the metal shell 40 .

[0103] In some feasible ways, the metal shell 40 is taken as a steel shell as an example for explanation. A stainless steel blank is punched using a punching device and a stamping die to obtain a stainless steel shell. The stainless steel shell includes a bottom plate 41 and a side plate 42. The side plate 42 has a folded edge 44. Then, by means of a bending device and a bending die, the number of folded edges 44 is increased on the basis of the stainless steel shell and the metal shell 40 is processed and formed. The angle of the folded edge 44 and the structure of the folded edge 44 are controlled by the bending die. The battery cell 30 is placed in the battery cell accommodating cavity 401 of the metal shell 40, and then the metal shell 40 and the cover body 50 are welded. After vacuum drying, electrolyte injection, standing, formation and other processes, the battery cell 10 is formed.

[0104] In some feasible ways, it is necessary to perform mechanical reliability tests on the processed battery cells 10, such as drop tests and roller tests. Taking the drop test as an example, the battery cell 10 is placed on a special fixture, and then the fixture releases the battery cell 10, and the battery cell 10 falls freely from a height of 1.5 meters (m) to the marble. Five rounds of drop tests are required for the same battery cell 10. In each round of drop tests, the battery cell 10 faces a different part of the marble. After the drop, check the appearance of the battery cell 10 and record the statistical probability of leakage. The total number of battery cells 10 used for testing is 10.

[0105] Table 1 exemplarily shows the comparative data of Examples 1 to 10 and Comparative Example 1 of the present application.

[0106] Embodiment 1:

[0107] The folding structure 43 of the present application includes two folding edges 44 (see Fig.14 As shown). The folded edge 44 is welded to the cover body 50. The angle K between the tangent line of the curved portion 442 at the connection point with the straight portion 441 and the straight portion 441 is 140°. The curved portion 442 is in an arc shape. The width of the weld 70 is 0.1 mm.

[0108] Embodiment 2:

[0109] The folding structure 43 of the present application includes three folding edges 44 (see Fig.13 As shown). The folded edge 44 is welded to the cover body 50. The angle K between the tangent line of the curved portion 442 at the connection point with the straight portion 441 and the straight portion 441 is 140°. The curved portion 442 is in an arc shape. The width of the weld 70 is 0.1 mm.

[0110] Embodiment 3:

[0111] The folding structure 43 of the present application includes four folding edges 44 (see Fig.12As shown). The folded edge 44 is welded to the cover body 50. The angle K between the tangent line of the curved portion 442 at the connection point with the straight portion 441 and the straight portion 441 is 140°. The curved portion 442 is in an arc shape. The width of the weld 70 is 0.1 mm.

[0112] Embodiment 4:

[0113] The folding structure 43 of the present application includes five folding edges 44 (see Fig.10 As shown). The folded edge 44 is welded to the cover body 50. The angle K between the tangent line of the curved portion 442 at the connection point with the straight portion 441 and the straight portion 441 is 140°. The curved portion 442 is in an arc shape. The width of the weld 70 is 0.1 mm.

[0114] Embodiment 5:

[0115] The folding structure 43 of the present application includes two folding edges 44. The folding edges 44 are welded to the cover body 50. The angle K between the tangent line of the curved portion 442 at the connection point with the straight portion 441 and the straight portion 441 is 140°. The curved portion 442 is in an arc shape. The width of the weld 70 is 0.05 mm.

[0116] Embodiment 6:

[0117] The folding structure 43 of the present application includes two folding edges 44. The folding edges 44 are welded to the cover body 50. The angle K between the tangent line of the curved portion 442 at the connection point with the straight portion 441 and the straight portion 441 is 140°. The curved portion 442 is in an arc shape. The width of the weld 70 is 0.2 mm.

[0118] Embodiment 7:

[0119] The folding structure 43 of the present application includes two folding edges 44. The folding edges 44 are welded to the cover body 50. The angle K between the tangent line of the curved portion 442 at the connection point with the straight portion 441 and the straight portion 441 is 140°. The curved portion 442 is in an arc shape. The width of the weld 70 is 0.3 mm.

[0120] Embodiment 8:

[0121] The folding structure 43 of the present application includes two folding edges 44. The folding edges 44 are welded to the cover body 50. The angle K between the tangent line of the curved portion 442 at the connection point with the straight portion 441 and the straight portion 441 is 140°. The curved portion 442 is in an arc shape. The width of the weld 70 is 0.04 mm.

[0122] Embodiment 9:

[0123] The folding structure 43 of the present application includes two folding edges 44. The folding edges 44 are welded to the cover body 50. The angle K between the tangent line of the curved portion 442 at the connection point with the straight portion 441 and the straight portion 441 is 140°. The curved portion 442 is in an arc shape. The width of the weld 70 is 0.4 mm.

[0124] Embodiment 10:

[0125] The folding structure 43 of the present application includes two folding edges 44. The folding edges 44 are welded to the cover body 50. The angle K between the first straight portion 44a and the second straight portion 44b is 90°. The width of the weld 70 is 0.1 mm.

[0126] Comparative Example 1:

[0127] See also Figure 2 As shown, in the related art, the metal shell 40 includes a flange 100. The flange 100 of the metal shell 40 is directly welded to the cover 50. The width of the weld 70 is 0.1 mm.

[0128] Comparative Example 2:

[0129] See also Fig.15 As shown, in the related art, the top of the side plate 42 of the metal shell 40 is directly welded to the cover 50. The width of the weld 70 is 0.05 mm.

[0130] Table 1:

[0131]

[0132] 1. Comparison of Example 1 with Comparative Example 1, Example 2 with Comparative Example 1, Example 3 with Comparative Example 1, Example 4 with Comparative Example 1, Example 1 with Comparative Example 2, Example 2 with Comparative Example 2, Example 3 with Comparative Example 2, or Example 4 with Comparative Example 2 shows that when the number of folded edges is two or more, the failure rate of the weld 70 is significantly reduced. In Comparative Example 1, the battery cell 30 impacts the metal shell 40, and the metal shell 40 is deformed outward, and the force is transmitted to the weld 70, and the weld 70 mainly bears the peeling force.

[0133] In Example 2 and Example 4, when the number of folded edges 44 is an odd number, the battery cell 30 impacts the metal shell 40, the metal shell 40 convexly deforms, and the force is transmitted to the weld 70, and the weld 70 will bear the peeling force. In Example 1 and Example 3, when the number of folded edges 44 is an even number, the battery cell 30 impacts the metal shell 40, the metal shell 40 convexly deforms, and the force is transmitted to the weld 70, and the weld 70 mainly bears the shear force. Therefore, it can be seen that when the number of folded edges 44 is an even number, the weld failure rate will be lower. When the number of folded edges is an odd number, the free end 431 of the bottom folded edge 44 faces outward, which will not affect the pole piece inside the battery cell, avoiding safety hazards.

[0134] When the width of the weld 70 is the same, the shear resistance performance of the weld 70 is greater than the peel resistance performance. Therefore, in Example 1 and Example 3, when the number of folded edges 44 is an even number, no weld 70 is broken when falling. In Example 2 and Example 4, the number of folded edges 44 is an odd number. The number of folded edges 44 is increased from 3 in Example 2 to 5 in Example 4. Although the force mode of the weld 70 against the impact of the battery cell 30 is not changed, the impact strength of the weld 70 remains unchanged, but the path for transmitting force from the metal shell 40 to the weld 70 is increased. Therefore, it can be seen that when the folded edges 44 are an odd number, the more the number of folded edges 44 is increased, the more obvious the improvement of the weld 70 breaking, and the lower the failure rate of leakage when falling.

[0135] 2. By comparing the data of Example 1, Example 5 to Example 9, it can be seen that the width of the weld 70 affects the impact strength of the weld 70. As the width of the weld 70 increases, the shear resistance of the weld 70 itself is proportional to the area of ​​the weld 70. At this time, the damage interface is the welding interface of the weld 70. When the width of the weld 70 is less than 0.05 mm, the impact strength of the weld 70 is too low, so the failure rate due to falling and leakage is high. When the width of the weld 70 is greater than 0.3 mm, due to the strength limitation of the weld 70 material itself, the impact strength of the weld 70 no longer increases with the increase of the width of the weld 70. Therefore, continuing to increase the width of the weld 70 cannot further improve the impact strength of the weld 70. Instead, it leads to an increase in the volume of the battery cell 10 and a decreasing trend in energy density.

[0136] According to some embodiments of the present application, an electrical device is further provided, comprising a battery cell 10 according to any of the above schemes, and the battery cell 10 is used to provide electrical energy to the electrical device.

[0137] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell, characterized in that: include: The shell assembly comprises a metal shell and a cover body, wherein the metal shell comprises a bottom plate and a side plate, wherein the bottom plate and the side plate are combined to form a cell accommodating cavity having an opening, The side plate includes a folding structure, the folding structure includes more than two foldings, the more than two foldings are connected in sequence, a buffer space is formed between any two adjacent foldings, one of the foldings adjacent to the cover body is connected to the cover body, and the cover body covers the battery cell accommodating cavity; The battery cell is arranged in the battery cell accommodating cavity.

2. The battery cell according to claim 1, characterized in that: The folded edge comprises a connected straight portion and a curved portion, and the straight portion of one folded edge is connected to the curved portion of another adjacent folded edge.

3. The battery cell according to claim 2, characterized in that: The bent portion is arc-shaped.

4. The battery cell according to claim 2, characterized in that: An opening size of the buffer space is larger than an opening size of the bent portion.

5. The battery cell according to claim 1, characterized in that: The metal shell and the cover body are stacked along the thickness direction of the cover body, and along the thickness direction of the cover body, the size of the folded edge structure is smaller than or equal to the size of the battery core.

6. The battery cell according to claim 1, characterized in that: In a direction perpendicular to the thickness direction of the cover body, the folded edge does not exceed the edge of the cover body.

7. The battery cell according to claim 1, characterized in that: The number of the folded edges is an even number.

8. The battery cell according to claim 1, characterized in that: The number of the folded edges is an odd number.

9. The battery cell according to claim 1, characterized in that: The folded edge comprises a first straight portion and a second straight portion connected to each other, wherein the first straight portion and the second straight portion are arranged to intersect each other, and the first straight portion of one folded edge is connected to the second straight portion of another folded edge.

10. The battery cell according to claim 2, characterized in that: An angle between a tangent line of the curved portion at a connection point with the straight portion and the straight portion is greater than 90° and less than 180°.

11. The battery cell according to claim 9, characterized in that: An included angle between the first straight portion and the second straight portion is greater than or equal to 80° and less than or equal to 100°.

12. The battery cell according to claim 1, characterized in that: One of the folded edges adjacent to the cover body is welded to the cover body to form a weld.

13. The battery cell according to claim 12, characterized in that: In a direction perpendicular to the thickness direction of the cover body, the width of the weld is in a range of 0.05 mm to 0.3 mm.

14. The battery cell according to any one of claims 1 to 13, characterized in that: The battery cell includes a pole, the metal shell includes four side plates, at least one side plate includes the folded edge structure, one side plate is provided with the pole, and the pole is electrically connected to the battery cell.

15. A metal shell for a battery cell, characterized in that: The metal housing comprises: Base plate; The side plate is connected to the bottom plate, and the bottom plate and the side plate are combined to form a battery cell accommodating cavity with an opening. The side plate includes a folding edge structure, and the folding edge structure includes more than two folding edges. The more than two folding edges are connected in sequence, and a buffer space is formed between any two adjacent folding edges.

16. An electrical equipment, characterized in that: Comprising the battery cell according to any one of claims 1 to 14.

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