Battery cell and electric equipment

Abstract

The invention provides a battery cell and electric equipment, the battery cell comprises a supporting piece and a winding type electrode assembly, and the electrode assembly comprises a first pole piece and a second pole piece; the first pole piece comprises a first section and a second section which are continuously arranged along the winding direction, the first section and the second section are connected at a first position, and the first position is aligned and adjacent to a second winding starting end of the second pole piece and is positioned on one side, deviating from the winding axis, of the second winding starting end; one end of the first section away from the first position is a first winding starting end; the supporting piece is connected to the surface, facing the winding axis, of the first section; in the opposite direction of the winding direction, the first section exceeds the first end, close to the first winding starting end, of the supporting piece, the supporting piece plays a role in supporting and reinforcing the first section, the risk of center collapse deformation of the electrode assembly is reduced, the safety performance of the battery cell is improved, the service life of the battery cell is prolonged, and accurate positioning in the winding direction is not needed when the supporting piece is arranged; the process difficulty is reduced, and the supporting piece is convenient to arrange.

Description

Technical Field

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

[0002] With the rapid development of new energy technologies, battery cells have been widely used in electronic equipment, electric vehicles, electric two-wheeled vehicles, power tools, etc. As the application of battery cells becomes more and more extensive, higher requirements are placed on the safety of battery cells. Summary of the invention

[0003] The embodiments of the present application provide a battery cell and an electrical device to improve the safety performance of the battery cell.

[0004] In the first aspect, an embodiment of the present application provides a battery cell, which includes a support member and a wound electrode assembly, the electrode assembly including a first electrode sheet and a second electrode sheet with opposite polarities; the first electrode sheet and the second electrode sheet are stacked and wound along a winding direction to form a winding structure, the first electrode sheet has a first winding starting end, the second electrode sheet has a second winding starting end, the first electrode sheet includes a first section and a second section arranged continuously along the winding direction, the first section and the second section are connected at a first position, in a direction perpendicular to the winding axis of the electrode assembly and passing through the second winding starting end, the first position is aligned with and adjacent to the second winding starting end, and is located on the side of the second winding starting end away from the winding axis, and the end of the first section away from the first position is the first winding starting end; the support member is connected to the surface of the first section facing the winding axis; wherein, along the winding direction, the support member has a first end close to the first winding starting end, and along the opposite direction of the winding direction, the first section exceeds the first end.

[0005] In one or more optional embodiments above, the end of the first section of the first pole piece away from the second section is the first winding starting end, then the first section is wound to form an inner circle layer, and the first section of the first pole piece is provided with a support member, and the support member plays a supporting and reinforcing role on the first section, thereby enhancing the deformation resistance of the first section, so that the inner circle layer of the first pole piece has a strong deformation resistance, reducing the risk of central collapse and deformation of the wound electrode assembly, thereby effectively reducing lithium deposition and improving the safety performance and service life of the battery cell. In the opposite direction of the winding direction, the first section exceeds the first end of the support member close to the first winding starting end, and the first end of the support member and the first winding starting end are not aligned, so when setting the support member, it is not necessary to accurately position it in the winding direction, which reduces the process difficulty and facilitates the setting of the support member. In addition, in the opposite direction of the winding direction, the first section exceeds the first end of the support member close to the first winding starting end, and the support member does not completely cover the surface of the first section facing the winding axis, reducing the amount of the support member, which is conducive to alleviating the problem of increased weight of the battery cell due to the setting of the support member.

[0006] In some embodiments of the first aspect of the present application, the first section includes a first current collecting layer and a first active material layer. Along the thickness direction of the first current collecting layer, the first current collecting layer has a first surface facing away from the winding axis and a second surface facing the winding axis. The first surface is provided with the first active material layer, and the support member is provided on the second surface.

[0007] In one or more of the above optional embodiments, the support member is connected to the second surface, and the first active material layer is not provided in at least part of the second surface, thereby reducing the first active material layer that does not exert capacity on the first electrode sheet, thereby reducing the waste of active material. The support member is connected to the second surface, and the risk of the first active material layer falling off due to the provision of the support member can also be reduced, further improving the safety performance of the battery cell.

[0008] In some embodiments of the first aspect of the present application, the support member is bonded or welded to the second surface.

[0009] In one or more of the above optional embodiments, the support member is bonded or welded to the second surface, which makes it easier to arrange the support member in the first section, and provides better connection strength between the support member and the second surface, thereby improving the connection stability of the support member.

[0010] In some embodiments of the first aspect of the present application, the support member is a metal member.

[0011] In one or more of the above optional embodiments, the support member is a metal member, which has better strength and rigidity, so that the inner circle layer of the first pole piece has a stronger ability to resist deformation, further reducing the risk of central collapse and deformation of the wound electrode assembly, thereby further effectively reducing lithium plating and improving the safety performance and service life of the battery cell.

[0012] In some embodiments of the first aspect of the present application, the material of the support member includes stainless steel.

[0013] In one or more of the above optional embodiments, stainless steel has the advantages of high corrosion resistance, heat resistance, durability, etc. The material of the support member includes stainless steel, which makes the support member have good corrosion resistance, heat resistance and durability. The support member can better adapt to the environment inside the battery cell, which is beneficial to improve the service life of the support member inside the battery cell, thereby improving the service life and safety performance of the battery cell.

[0014] In some embodiments of the first aspect of the present application, along the winding direction, the support member does not exceed the first position.

[0015] In one or more of the above optional embodiments, the support member does not exceed the first position along the winding direction, thereby reducing the risk of the support member extending to between the first pole piece and the second pole piece and piercing the isolation membrane to cause a short circuit in the battery cell. It can also alleviate the problem of a larger structural size of the electrode assembly of the battery cell due to the provision of the support member, and alleviate the size differences of various parts of the electrode assembly, thereby reducing the risk of uneven force on the pole pieces due to expansion of the electrode assembly during the battery cell cycle.

[0016] In some embodiments of the first aspect of the present application, along the winding direction, the support member has a second end opposite to the first end, and the second end is spaced apart from the first position.

[0017] In one or more of the above optional embodiments, the second end is spaced apart from the first position along the winding direction, leaving a margin for misalignment between the first pole piece and the second pole piece caused by expansion of the electrode assembly during the battery cell cycle, thereby reducing the risk of the support member extending between the first pole piece and the second pole piece after the electrode assembly expands, thereby reducing the risk of the support member extending between the first pole piece and the second pole piece and puncturing the isolation membrane to cause a short circuit in the battery cell, thereby further improving the safety performance of the battery cell.

[0018] In some embodiments of the first aspect of the present application, along the winding direction, a distance between the second end and the first position is K, and 0.5 mm≤K≤15 mm.

[0019] In one or more of the above optional embodiments, by K≥0.5mm, there is a sufficient distance between the second end and the first position in the winding direction, so that there is enough margin for the expansion of the electrode assembly during the battery cell cycle, resulting in the misalignment between the first and second pole pieces, thereby reducing the risk of the support member extending between the first and second pole pieces after the electrode assembly expands, thereby reducing the risk of the support member extending between the first and second pole pieces after the electrode assembly expands and piercing the isolation membrane to cause a short circuit in the battery cell, further improving the safety performance of the battery cell. By K≤15mm, it is avoided that the distance between the second end and the first position is too large in the winding direction, resulting in insufficient support strength of the support member for the first section and the inability to effectively improve the problem of the collapse of the center hole of the wound electrode assembly. Therefore, 0.5mm≤K≤15mm can not only reduce the risk of the support member extending between the first and second pole pieces after the electrode assembly expands and piercing the isolation membrane to cause a short circuit in the battery cell, further improving the safety performance of the battery cell, but also effectively improve the problem of the collapse of the center hole of the wound electrode assembly.

[0020] In some embodiments of the first aspect of the present application, the bending strength of the support member is H, 30MPa≤H≤300MPa.

[0021] In one or more of the above optional embodiments, by H≥30MPa, the support member has a higher anti-deformation ability, so that the support member plays a better supporting and reinforcing role on the first section, thereby enhancing the anti-deformation ability of the first section, so that the inner circle layer of the first pole piece has a strong anti-deformation ability, reducing the risk of central collapse and deformation of the wound electrode assembly, thereby effectively reducing lithium plating and improving the safety performance and service life of the battery cell. By H≤300MPa, when the anti-deformation ability of the component support member is sufficient, avoid selecting a support member with too high bending strength, which leads to increased cost and excessive performance of the support member. Therefore, 300MPa≤H≤300MPa can not only make the inner circle layer of the first pole piece have a strong anti-deformation ability, reduce the risk of central collapse and deformation of the wound electrode assembly, thereby effectively reducing lithium plating, improving the safety performance and service life of the battery cell, but also control the cost of the support member and prevent the support member from having excessive performance.

[0022] In some embodiments of the first aspect of the present application, 200 MPa≤H≤300 MPa.

[0023] In one or more of the above optional embodiments, 200MPa≤H≤300MPa can further enhance the strength of the inner ring layer and reduce the risk of collapse and deformation of the center of the electrode assembly. In some embodiments of the first aspect of the present application, the elastic modulus of the support member is G, 1.5GPa≤G≤200GPa.

[0024] In one or more of the above optional embodiments, by setting G≥1.5GPa, the elastic deformation capacity of the support is better, which will cause the inner circle layer of the first pole piece to rebound with a larger diameter, thereby supporting the inner circle layer and reducing the risk of the inner circle layer of the first pole piece collapsing inward, thereby effectively reducing lithium plating and improving the safety performance and service life of the battery cell. By setting G≤200GPa, when the elastic deformation capacity of the component support is sufficient, it is avoided to select a support member with too high an elastic modulus, which leads to increased costs and excessive performance of the support member. Therefore, 1.5GPa≤G≤200GPa can not only reduce the risk of the inner circle layer of the first pole piece collapsing inward, thereby effectively reducing lithium plating and improving the safety performance and service life of the battery cell, but also control the cost of the support member and prevent excessive performance of the support member.

[0025] In some embodiments of the first aspect of the present application, 100 GPa≤G≤200 GPa.

[0026] In one or more of the above optional embodiments, by limiting 100 GPa≤G≤200 GPa, the elastic deformation capacity of the support member is further improved, thereby reducing the risk of the inner circle layer of the first pole piece collapsing inwards.

[0027] In some embodiments of the first aspect of the present application, along the opposite direction of the winding direction, the first section includes a first portion extending beyond the first end, and the length of the first portion is L, 0.5 mm≤L≤15 mm.

[0028] In one or more of the above optional embodiments, by L≥0.5mm, the size of the portion of the first section that exceeds the first end in the opposite direction of the winding direction is large enough, which is more convenient for the support member to be set. By L≤15mm, the problem of reduced energy density of the battery cell caused by the first section exceeding the first end in the opposite direction of the winding direction is alleviated. Therefore, 0.5mm≤L≤15mm is more convenient for the support member to be set, and can also alleviate the problem of reduced energy density of the battery cell caused by the first section exceeding the first end in the opposite direction of the winding direction.

[0029] In some embodiments of the first aspect of the present application, when viewed along a direction perpendicular to the winding axis of the electrode assembly and passing through the second winding start end, the first end and the second winding start end are not coplanar.

[0030] In one or more of the above optional embodiments, the first end and the second winding starting end are not coplanar, which is conducive to alleviating the problem of larger structural dimensions of the electrode assembly due to the provision of support members in the battery cell, and alleviating the size differences of various parts of the electrode assembly, thereby reducing the risk of uneven force on the pole pieces due to expansion of the electrode assembly during the battery cell cycle.

[0031] In some embodiments of the first aspect of the present application, along the winding direction, the support member has a second end, and the second end is arranged opposite to the first end; when observed along the winding axis of the vertical electrode assembly and passing through the second winding starting end, the second end and the second winding starting end are not coplanar.

[0032] In one or more of the above optional embodiments, the second end and the second winding starting end are not coplanar, which is conducive to alleviating the problem of larger structural dimensions of the electrode assembly due to the provision of support members in the battery cell, and alleviating the size differences of various parts of the electrode assembly, thereby reducing the risk of uneven force on the pole pieces due to expansion of the electrode assembly during the battery cell cycle.

[0033] In some embodiments of the first aspect of the present application, the support member is wound at least once along the winding direction.

[0034] In one or more of the above optional embodiments, the support member is wound at least one circle along the winding direction, so that the inner circle layer of the first pole piece has a stronger deformation resistance, further reducing the risk of central collapse and deformation of the wound electrode assembly, thereby effectively reducing lithium plating and improving the safety performance and service life of the battery cell.

[0035] In some embodiments of the first aspect of the present application, along the winding direction, the support member has a second end, and the second end is arranged opposite to the first end; when observed along the winding axis of the vertical electrode assembly and passing through the first end, the first end and the second end are coplanar.

[0036] In one or more of the above optional embodiments, by observing along the winding axis of the vertical electrode assembly and passing through the first end, the first end and the second end are coplanar, and the number of turns of the support member around the winding axis is a full turn, which is convenient for controlling the length of the support member along the winding direction and the number of turns of the support member.

[0037] In some embodiments of the first aspect of the present application, the support member is wound at least twice along the winding direction.

[0038] In one or more of the above optional embodiments, by winding the support member at least two times along the winding direction, the deformation resistance of the inner circle layer of the first pole piece is further enhanced, and the risk of central collapse and deformation of the wound electrode assembly is further reduced, thereby effectively reducing lithium plating and improving the safety performance and service life of the battery cell.

[0039] In some embodiments of the first aspect of the present application, the first pole piece is a negative pole piece, and the second pole piece is a positive pole piece.

[0040] In one or more of the above optional embodiments, the first pole piece is a negative pole piece, the second pole piece is a positive pole piece, and the first section of the negative pole piece forms an inner circle layer of the electrode assembly, which is conducive to the battery cell having a higher energy density.

[0041] In some embodiments of the first aspect of the present application, the battery cell is a button battery.

[0042] In some embodiments of the first aspect of the present application, the battery cell includes a shell, and the electrode assembly is accommodated in the shell; the shell includes a shell and a cover, the shell has an opening, the cover covers the opening, and along the extension direction of the winding axis, the shell has a bottom wall opposite to the cover;

[0043] The battery cell also includes a first pole ear and a second pole ear, the first pole ear is electrically connected to the first pole sheet, the second pole ear is electrically connected to the second pole sheet, the second pole ear is welded to the bottom wall, and along the extension direction of the winding axis, the support member extends beyond one end of the first pole sheet close to the bottom wall and one end of the second pole sheet close to the bottom wall, and one end of the support member close to the bottom wall abuts against the surface of the second pole ear facing the electrode assembly.

[0044] In one or more of the above optional embodiments, in a traditional button battery, one of the pole ears needs to be connected to the bottom wall of the shell, and a columnar support column is passed through the middle of the battery cell to support the surface of the pole ear electrically connected to the bottom wall facing the electrode assembly in the extension direction of the winding axis, so that the second pole ear and the bottom wall of the shell can be welded from the outside of the shell. When the second pole ear is welded to the bottom wall, the support member is set to extend beyond the end of the first pole piece close to the bottom wall and the end of the second pole piece close to the bottom wall, and the end of the support member close to the bottom wall is against the surface of the second pole ear facing the electrode assembly, which can directly support the second pole ear, so that the bottom wall and the second pole ear are in contact in the extension direction of the winding axis, which facilitates the welding of the second pole ear and the bottom wall, and can also avoid adding other structures such as support columns to keep the bottom wall and the second pole ear in contact during the manufacturing process, which makes the inner hole of the battery cell larger.

[0045] In some embodiments of the first aspect of the present application, the diameter of the central hole of the electrode assembly is 0.6 mm to 2.3 mm.

[0046] In one or more of the above optional embodiments, by extending along the winding axis, the support member exceeds one end of the first pole piece close to the bottom wall and one end of the second pole piece close to the bottom wall, and one end of the support member close to the bottom wall abuts against the surface of the second pole ear facing the electrode assembly, so that the center hole of the electrode assembly can be made smaller, which can be less than 2.3mm. The hole greater than 0.6mm is caused by the winding needle of the inner circle.

[0047] In a second aspect, an embodiment of the present application provides an electrical device, and the electrical device includes a battery cell provided by any of the above embodiments.

[0048] In one or more of the above optional implementations, the battery cell provided in any of the above embodiments has higher safety performance and longer service life, and the electrical equipment powered by the battery cell has better power reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope.

[0050] Figure 1 An exploded diagram of a battery cell provided in some embodiments of the present application;

[0051] Figure 2 A schematic diagram of the structure of an electrode assembly provided in some embodiments of the present application;

[0052] Figure 3 for Figure 2 The enlarged view of B1 in the middle;

[0053] Figure 4 A schematic diagram of a first pole piece of a support member provided in some embodiments of the present application, viewed along the thickness direction of the first pole piece;

[0054] Figure 5 A first pole piece provided with a support member along a width direction of the first pole piece provided in some embodiments of the present application;

[0055] Figure 6 A schematic structural diagram of a first pole piece provided with a support member provided in some other embodiments of the present application;

[0056] Figure 7 A schematic diagram of the structure of an electrode assembly provided in some other embodiments of the present application;

[0057] Figure 8 A schematic diagram of the structure of an electrode assembly provided in some further embodiments of the present application;

[0058] Fig. 9 A schematic diagram of the structure of a second pole piece is provided for some embodiments of the present application;

[0059] Fig.10 A cross-sectional view of a battery cell provided in some embodiments of the present application.

[0060] Icons: 100-battery cell; 10-housing; 11-housing; 111-opening; 112-bottom wall; 12-cover; 13-electrode terminal; 20-electrode assembly; 21-first pole piece; 211-first section; 2111-first current collecting layer; 21111-first surface; 211111-first region; 211112-second region; 21112-second surface; 2112-first active material layer; 21121-third end; 2113-first part; 212-second section; 2121-second current collecting layer; 213-first winding starting end; 214-first pole ear; 22-second pole piece; 221-second winding starting end; 222-second pole ear; 23-isolating membrane; Q-first position; A1-inner ring layer; 30-support member; 31-first end; 32-second end; A2-outer ring layer; X-winding direction; X'-length direction of the first pole piece; Y-thickness direction of the first pole piece; Z-width direction of the first pole piece; P-winding axis; P1-first reference plane; P2-second reference plane; P3-third reference plane; M-center hole. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0062] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application claimed for protection, but merely represents selected embodiments of the present application. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict.

[0063] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0064] In the description of the embodiments of the present application, it should be noted that the indicated orientation or position relationship is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the application is usually placed when in use, or is the orientation or position relationship commonly understood by technical personnel in this field. It is only for the convenience of describing 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. Therefore, it cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0066] At present, judging from the development of the market situation, the application of battery cells is becoming more and more extensive. Battery cells are widely used in electric vehicles such as electric bicycles, electric motorcycles, electric vehicles, as well as electric tools, drones, energy storage equipment and other fields. With the continuous expansion of the application field of battery cells, the market demand is also constantly expanding, and the requirements for battery cell safety are becoming higher and higher.

[0067] For wound cells, the electrode assembly of the cell is a wound structure. After the positive electrode sheet, separator and negative electrode sheet of the electrode assembly are wound, a center hole will be formed in the center of the electrode assembly. With the use of the cell, the expansion stress of the negative electrode sheet increases, and the expansion of the negative electrode sheet will squeeze in the direction of the center hole, causing the circle of the electrode assembly close to the center hole to collapse toward the center. The electrode sheet close to the center hole is prone to wrinkling after collapse. The electrode sheet at this location is uneven, resulting in a gully-like gap between the electrode sheets, which hinders ion transmission and eventually leads to lithium precipitation, which in turn reduces the safety performance of the cell. In order to alleviate the problem of collapse of the inner layer of the electrode assembly, in the related art, a support column is inserted into the center air, but there are multiple circles of separators in the center hole. Inserting the support column is easy to squeeze the separator or the electrode sheet, resulting in abnormal quality. After the support column is inserted, there is a tolerance matching problem between the support column and the center hole, and there is a certain gap, so there is still an internal collapse phenomenon after the cycle.

[0068] Based on the above considerations, in order to alleviate the problem that the circle layer of the electrode assembly near the center hole is easy to collapse, resulting in reduced safety performance of the battery cell, an embodiment of the present application provides a battery cell, which includes a support member and a wound electrode assembly, the electrode assembly including a first pole sheet and a second pole sheet with opposite polarities; the first pole sheet and the second pole sheet are stacked and wound along the winding direction to form a winding structure, the first pole sheet has a first winding starting end, and the second pole sheet has a second winding starting end, the first pole sheet includes a first section and a second section arranged continuously along the winding direction, the first section and the second section are connected at a first position, in a direction perpendicular to the winding axis of the electrode assembly and passing through the second winding starting end, the first position is aligned with and adjacent to the second winding starting end, and is located on the outside of the second winding starting end, and the end of the first section away from the first position is the first winding starting end; the support member is connected to the surface of the first section facing the winding axis of the electrode assembly; wherein, along the winding direction, the support member has a first end close to the first winding starting end, and along the opposite direction of the winding direction X, the first section exceeds the first end.

[0069] The end of the first section of the first pole piece away from the second section is the first winding starting end, and the first section is wound to form an inner circle layer. The first section of the first pole piece is provided with a support member, and the support member supports and strengthens the first section, thereby enhancing the deformation resistance of the first section, so that the inner circle layer of the first pole piece has a strong deformation resistance, reducing the risk of center collapse and deformation of the wound electrode assembly, thereby effectively reducing lithium plating and improving the safety performance and service life of the battery cell.

[0070] In the opposite direction of the winding direction, the first section exceeds the first end of the support member close to the first winding starting end, so the first end of the support member and the first winding starting end are not aligned. Therefore, when setting the support member, there is no need for precise positioning in the winding direction, which reduces the process difficulty and facilitates the setting of the support member.

[0071] The battery cell disclosed in the embodiment of the present application can be used in, but not limited to, electric two-wheeled vehicles, electric tools, drones, energy storage devices and other electrical equipment. The battery cell with the working condition of the present application can also be used as a power supply system for electrical equipment, which is conducive to improving the safety performance of the battery cell.

[0072] The present application provides an electric device using a battery cell as a power source, and the electric device may be, but is not limited to, electronic equipment, electric tools, electric vehicles, drones, and energy storage devices. Among them, electronic equipment may include mobile phones, tablets, laptops, etc., electric tools may include electric drills, electric saws, etc., and electric vehicles may include electric cars, electric motorcycles, electric bicycles, etc.

[0073] like Figure 1 , Figure 2 As shown, an embodiment of the present application provides a battery cell 100 , which includes a housing 10 and an electrode assembly 20 ; the electrode assembly 20 is accommodated in the housing 10 .

[0074] The housing 10 forms a storage space. The storage space can be used to store the electrode assembly 20, electrolyte, etc. The housing 10 can be a hard shell, such as a steel shell or an aluminum shell, forming a steel shell battery cell or an aluminum shell battery cell. The housing 10 can also be formed of a softer material, such as an aluminum-plastic film or a steel-plastic film, forming a soft-pack battery cell.

[0075] The housing 10 may include a shell 11 and a cover 12. The shell 11 has an opening 111 at at least one end. The cover 12 is used to cover the opening 111 of the shell 11, so that the shell 11 and the cover 12 define a receiving space together. Figure 1 and Fig. 9 As shown, along the extension direction of the winding axis P, the housing 11 has a bottom wall 112 opposite to the cover 12. An electrode terminal 13 is insulated and disposed on the cover 12. The electrode terminal 13 may also be referred to as a pole.

[0076] The electrode assembly 20 includes a separator 23 , a first pole piece 21 , another separator 23 , and a second pole piece 22 .

[0077] The first pole piece 21 and the second pole piece 22 have opposite polarities, that is, one of the first pole piece 21 and the second pole piece 22 is a positive pole piece, and the other of the first pole piece 21 and the second pole piece 22 is a negative pole piece. Figure 2 As shown, the first pole piece 21 is a negative pole piece, and the second pole piece 22 is a positive pole piece.

[0078] The first electrode sheet 21 includes a first current collector and a first active material layer 2112. Along the thickness direction Y of the first electrode sheet, at least one side of the first current collector is provided with the first active material layer 2112. In the embodiment where the first electrode sheet 21 is a positive electrode sheet, the first current collector is a positive electrode current collector, and the first active material layer 2112 is a positive electrode active material layer. A positive electrode active material layer is provided on at least one side of the positive electrode current collector. For lithium-ion batteries, the material of the positive electrode current collector may be aluminum. The positive electrode active material layer may be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide, etc. The positive electrode current collector may be a composite current collector or a non-composite current collector.

[0079] In the embodiment where the first electrode sheet 21 is a negative electrode sheet, the first current collector is a negative electrode current collector, and the first active material layer 2112 is a negative electrode active material layer. A negative electrode active material layer is provided on at least one side of the negative electrode current collector. For lithium-ion batteries, the material of the negative electrode current collector may be copper. The negative electrode current collector may be a composite current collector or a non-composite current collector. The negative electrode active material may be a carbon material or a silicon material, etc.

[0080] The separator 23 insulates and separates the positive electrode sheet and the negative electrode sheet to reduce the risk of short circuit of the battery cell 100. The material of the separator 23 may include polypropylene (PP) or polyethylene (PE).

[0081] The electrode assembly 20 is a wound structure. Specifically, the first electrode sheet 21, the separator 23, the second electrode sheet 22 and the other separator 23 are stacked and then wound to form an electrode assembly 20 with a wound structure; or, the separator 23, the first electrode sheet 21, the other separator 23 and the second electrode sheet 22 are stacked and then wound to form an electrode assembly 20 with a wound structure. The wound electrode assembly 20 can be a flat wound electrode assembly 20 or a cylindrical electrode assembly 20. In the embodiment where the electrode assembly 20 is a cylindrical structure, the battery cell 100 can be a cylindrical battery cell 100 or a columnar battery cell 100. Figure 1 FIG. 4 shows a case where the battery cell 100 is a cylindrical battery cell. Figure 2 2 shows a case where the electrode assembly 20 is a cylindrical structure. In some embodiments, the battery cell 100 may be a button cell. Figure 1 FIG. 4 shows a case where the battery cell 100 is a button battery.

[0082] The innermost pole piece of the electrode assembly 20 is a part of the first pole piece 21. It can be understood that the winding starting pole piece of the electrode assembly 20 is the first pole piece 21, and the innermost pole piece of the second pole piece 22 is located outside the innermost pole piece of the first pole piece 21. Figure 2As shown, the first electrode sheet 21 is a negative electrode sheet, the second electrode sheet 22 is a positive electrode sheet, and the first section 211 of the negative electrode sheet forms the inner circle layer A1 of the electrode assembly 20, which is beneficial for the battery cell 100 to have a higher energy density.

[0083] The outer side of the innermost circle of the first pole piece 21 refers to the side of the innermost circle of the first pole piece 21 away from the winding axis P of the electrode assembly 20. The axis P is formed by looking down at the electrode assembly 20, with the center of the circle formed by the outermost circle of the entire electrode assembly 20 as the axis P. A certain deviation is a normal measurement deviation. Alternatively, along the radial direction of the electrode assembly 20, the innermost circle of the second pole piece 22 is farther away from the winding axis P of the electrode assembly 20 than the innermost circle of the first pole piece 21.

[0084] like Figure 4 As shown, in some embodiments, a first pole ear 214 may be further provided on the outer ring layer A2 formed by the second section 212. The first pole ear 214 and the second current collecting layer 2121 may be integrally formed, such as forming the first pole ear 214 of the first pole piece 21 by die-cutting the substrate. The first pole ear 214 and the second current collecting layer 2121 may also be separately provided, and then the first pole ear 214 and the second current collecting layer 2121 are welded and connected by conductive adhesive, thereby realizing electrical connection between the pole ear and the second current collecting layer 2121. In some embodiments, the first pole ear 214 may be electrically connected to the housing 10, such as by welding or conductive adhesive. In other embodiments, the first pole ear 214 may also be electrically connected to the electrode terminal 13, such as by welding or conductive adhesive.

[0085] The first electrode tab 214 protrudes from one end of the first active material layer 2112 along the width direction Z of the first electrode sheet. When the first electrode sheet 21 is in the unfolded state, the width direction Z, the length direction X' and the thickness direction Y of the first electrode sheet are perpendicular to each other.

[0086] like Figure 2-Figure 5 As shown, in some embodiments, the first pole piece 21 includes a first section 211 and a second section 212 arranged continuously along the winding direction X, and the first section 211 and the second section 212 are connected at a first position Q. The first pole piece 21 has a first winding start end 213, which is the winding start end of the first pole piece 21 and is also the end of the first pole piece 21 closest to the winding axis P in the winding direction X.

[0087] like Figure 5 As shown, the first section 211 includes a first current collector layer 2111 and a first active material layer 2112. The first current collector layer 2111 is provided with the first active material layer on at least one side in the thickness direction thereof. The first current collector layer is a portion of the first current collector along the winding direction X.

[0088] In some embodiments, the first current collecting layer 2111 may have the first active material layer 2112 on both sides of a portion of the area; the first current collecting layer 2111 may have the first active material layer 2112 on one side of a portion of the area, and no first active material layer 2112 on the other side, that is, a portion of the first section 211 is a double-sided coating structure, and the other portion of the first section 211 is a single-sided coating structure.

[0089] In some embodiments, the first active material layer 2112 is disposed on both sides of any region of the first current collecting layer 2111 , that is, the first section 211 is a double-sided coating structure.

[0090] Of course, the first current collecting layer 2111 may also be provided with the first active material layer 2112 only on one side and not on the other side, that is, the first section 211 is a single-sided coating structure.

[0091] One end of the first section 211 away from the first position Q is a first winding start end 213. The first section 211 is wound to form the inner circle layer A1 of the first pole piece 21, which is also the inner circle layer A1 of the electrode assembly 20.

[0092] like Figure 5 As shown, the second section 212 includes a second current collector layer 2121 and a first active material layer 2112. The second current collector layer 2121 is provided with the first active material layer on at least one side in the thickness direction. The second current collector layer 2121 is another part of the first current collector along the winding direction X.

[0093] In some embodiments, the first active material layer 2112 may be provided on both sides of a portion of the second current collecting layer 2121; the first active material layer 2112 may be provided on one side of a portion of the second current collecting layer 2121, and no first active material layer 2112 is provided on the other side, that is, a portion of the second section 212 is a double-sided coating structure, and the other portion of the second section 212 is a single-sided coating structure.

[0094] In some embodiments, the first active material layer 2112 is disposed on both sides of any region of the second current collecting layer 2121 , that is, the second section 212 is a double-sided coating structure.

[0095] Of course, the second current collecting layer 2121 may also be provided with the first active material layer 2112 only on one side and not on the other side, and the second section 212 is a single-sided coating structure.

[0096] Please refer to Figure 2-Figure 5 The second section 212 is wound to form the inner circle layer A1 of the first pole piece 21 , and the outer circle layer A2 formed by the second section 212 is located outside the inner circle layer A1 formed by the first section 211 .

[0097] The second pole piece 22 has a second winding start end 221 , which is the winding start end of the second pole piece 22 and is also the end of the second pole piece 22 closest to the winding axis P in the winding direction X.

[0098] In this embodiment, if Figure 3 As shown, in a direction perpendicular to the winding axis P of the electrode assembly 20 and passing through the second winding start end 221 , the first position Q is aligned with and adjacent to the second winding start end 221 , and is located outside the second winding start end 221 .

[0099] Definition: the plane passing through the second winding starting end 221 is the first reference plane P1, and the position where the first reference plane P1 intersects with the first pole piece 21 adjacent to the second winding starting end 221 and located outside the second winding starting end 221 is the first position Q, so that in the direction perpendicular to the winding axis P of the electrode assembly 20 and passing through the second winding starting end 221, the first position Q is aligned with and adjacent to the second winding starting end 221, and is located outside the second winding starting end 221. The outside of the second winding starting end 221 refers to the side of the second winding starting end 221 away from the winding axis P in the direction parallel to the end face of the second winding starting end 221 and perpendicular to the winding axis P.

[0100] like Figure 2-Figure 5 As shown, in some embodiments, the battery cell 100 further includes a support member 30 , which is connected to a surface of the first segment 211 facing the winding axis P of the electrode assembly 20 .

[0101] The end of the first section 211 of the first pole piece 21 away from the second section 212 is the first winding starting end 213, and the first section 211 is wound to form an inner circle layer A1. The first section 211 of the first pole piece 21 is provided with a support member 30, and the support member 30 supports and strengthens the first section 211, thereby enhancing the deformation resistance of the first section 211, so that the inner circle layer A1 of the first pole piece 21 has strong deformation resistance, reducing the risk of center collapse and deformation of the wound electrode assembly 20, thereby effectively reducing lithium plating and improving the safety performance and service life of the battery cell 100.

[0102] The surface of the first section 211 facing the winding axis P may be the surface of the first active material layer 2112 , the surface of the first current collecting layer 2111 , or a portion of the surface of the first active material layer 2112 and a portion of the surface of the first current collecting layer 2111 .

[0103] like Figure 2-Figure 5As shown, along the thickness direction of the first current collecting layer 2111, the first current collecting layer 2111 has a first surface 21111 and a second surface 21112 opposite to each other, the first surface 21111 is arranged away from the winding axis P, and the second surface 21112 is arranged facing the winding axis P. The thickness direction of the first current collecting layer 2111 is parallel to the thickness direction Y of the first pole piece.

[0104] A first active material layer 2112 is provided on the first surface 21111 .

[0105] The first active material layer 2112 may also be provided on the second surface 21112. If the second surface 21112 is completely covered by the first active material layer 2112, the surface of the first section 211 facing the winding axis P is the surface of the first active material layer 2112 of the second surface 21112 facing the winding axis P. The support member 30 may be provided on the surface of the first active material layer 2112 of the second surface 21112 facing the winding axis P.

[0106] The second surface 21112 may not be provided with the first active material layer 2112, and the surface of the first section 211 facing the winding axis P is the second surface 21112, and the support member 30 may be provided on the second surface 21112. In this case, the second surface 21112 is not provided with the first active material layer 2112, which reduces the first active material layer 2112 that does not play a capacity role on the first electrode 21, thereby reducing the waste of active materials. The support member 30 is connected to the second surface 21112, and the risk of the first active material layer 2112 falling off due to the provision of the support member 30 can also be reduced, further improving the safety performance of the battery cell 100.

[0107] The first active material layer 2112 may be provided in a part of the second surface 21112, and the first active material layer 2112 may not be provided in another part of the second surface 21112. Then, the surface of the first section 211 facing the winding axis P is formed by the surface of the first active material layer 2112 of the second surface 21112 facing the winding axis P and a part of the second surface 21112. In this case, the support member 30 may be provided on the surface of the first active material layer 2112 of the second surface 21112 facing the winding axis P and / or the area of ​​the second surface 21112 where the first active material layer 2112 is not provided. The first active material layer 2112 is not provided in a part of the second surface 21112, which reduces the first active material layer 2112 on the first electrode 21 that does not exert its capacity, thereby reducing the waste of active materials. The support member 30 is connected to the second surface 21112, and can also reduce the risk of the first active material layer 2112 falling off due to the provision of the support member 30, further improving the safety performance of the battery cell 100.

[0108] In an embodiment where the first active material layer 2112 is not disposed on at least a portion of the second surface 21112, the region of the second surface 21112 where the first active material layer 2112 is not disposed may extend to the first winding start end 213 in the opposite direction of the winding direction X. For example, Figure 3 , Figure 4 As shown, the second surface 21112 is not provided with the first active material layer 2112, and the support member 30 is connected to the second surface 21112. Figure 6 As shown, the second surface 21112 includes a first area 211111 and a second area 211112. The first area 211111 is provided with a first active material layer 2112. Along the opposite direction of the winding direction X, the second area 211112 extends to the first winding starting end 213, and the support member 30 is connected to the second area 211112.

[0109] In the embodiment where the support member 30 is connected to the second surface 21112, the support member 30 and the second surface 21112 may be connected by adhesive bonding. For example, an adhesive layer may be coated on the support member 30 and the second surface 21112 to connect the support member 30 and the second surface 21112 through the adhesive layer, or the support member 30 and the second surface 21112 may be connected by adhesive tape.

[0110] In the embodiment where the support member 30 is connected to the second surface 21112, the support member 30 and the second surface 21112 may be welded. The support member 30 and the second surface 21112 may be welded by laser welding, ultrasonic welding, or the like.

[0111] The support member 30 is bonded or welded to the second surface 21112 , which makes it easier to arrange the support member 30 in the first section 211 , and there is better connection strength between the support member 30 and the second surface 21112 , thereby improving the connection stability of the support member 30 .

[0112] In other embodiments, the support member 30 may be disposed on the first section 211 by spraying, coating, or the like.

[0113] Along the winding direction X, the support member 30 has a second end 32 , and the second end 32 is arranged opposite to the first end 31 , that is, the second end 32 and the first end 31 are respectively located at two ends of the support along the winding direction X.

[0114] Along the winding direction X, the second active material layer closest to the support member 30 has a third end 21121 facing the second end 32. The third end 21121 can contact the second end 32 to avoid exposing the empty foil between the second end 32 and the third end 21121, thereby reducing the risk of short circuit of the battery cell 100.

[0115] Along the winding direction X, there may be a gap between the third end 21121 and the second end 32, so as to reduce the occurrence of problems such as wrinkling of the support member 30, peeling of the support member 30 from the second surface 21112, and de-powdering of the second active material layer due to squeezing of the support member 30 and the first active material layer 2112 in the winding direction X during winding.

[0116] The third end 21121 may be an end of the first active material layer 2112 on the side of the second section 212 facing the winding axis P, which is opposite to the support member 30 in the winding direction X. The third end 21121 may also be an end of the first active material layer 2112 on the side of the first section 211 facing the winding axis P, which is opposite to the support member 30 in the winding direction X. Figure 5 , it is shown that in the winding direction X, the first active material layer 2112 closest to the support member 30 is the first active material layer 2112 on the second section 212 , and there is a gap between the third end 21121 of the first active material layer 2112 closest to the support member 30 and the second end 32 of the support member 30 . Figure 6 , it is shown that in the winding direction X, the first active material layer 2112 closest to the support member 30 is the first active material layer 2112 on the first section 211 , and there is a gap between the third end 21121 of the first active material layer 2112 closest to the support member 30 and the second end 32 of the support member 30 .

[0117] Combined with reference Figure 3-Figure 5 As shown, along the winding direction X, the support member 30 has a first end 31 close to the first winding starting end 213 , and along the opposite direction of the winding direction X, the first section 211 exceeds the first end 31 .

[0118] In the opposite direction of the winding direction X, the first section 211 exceeds the first end 31 of the support member 30 close to the first winding starting end 213, and the first end 31 of the support member 30 and the first winding starting end 213 are not aligned, so when setting the support member 30, it is not necessary to accurately position it in the winding direction X, which reduces the process difficulty and facilitates the setting of the support member 30. In addition, in the opposite direction of the winding direction X, the first section 211 exceeds the first end 31 of the support member 30 close to the first winding starting end 213, and the support member 30 does not completely cover the surface of the first section 211 facing the winding axis P, which reduces the amount of the support member 30, which is conducive to alleviating the problem of increased weight of the battery cell 100 due to the setting of the support member 30.

[0119] like Figure 3-Figure 5 As shown, in some embodiments, along the opposite direction of the winding direction X, the first section 211 includes a first portion 2113 extending beyond the first end 31 , and the length of the first portion 2113 is L, 0.5 mm≤L≤15 mm.

[0120] Exemplarily, L can be 0.5mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, etc.

[0121] When L≥0.5mm, the size of the portion of the first section 211 that exceeds the first end 31 in the opposite direction of the winding direction X is large enough, which is more convenient for the support member 30 to be set. When L≤15mm, the problem of the energy density of the battery cell 100 being reduced due to the first section 211 exceeding the first end 31 in the opposite direction of the winding direction X is alleviated. Therefore, 0.5mm≤L≤15mm is more convenient for the support member 30 to be set, and the problem of the energy density of the battery cell 100 being reduced due to the first section 211 exceeding the first end 31 in the opposite direction of the winding direction X can be alleviated.

[0122] The support member 30 may be made of a variety of materials, such as plastic, ceramic, metal, etc. In some embodiments, the support member 30 is a metal member, such as an aluminum sheet, a copper sheet, a steel sheet, etc.

[0123] The support member 30 is a metal member having better strength and rigidity, so that the inner ring layer A1 of the first pole piece 21 has a stronger ability to resist deformation, further reducing the risk of central collapse and deformation of the wound electrode assembly 20, thereby further effectively reducing lithium plating and improving the safety performance and service life of the battery cell 100.

[0124] In some embodiments, the material of the support member 30 includes stainless steel. Stainless steel has advantages such as high corrosion resistance, heat resistance, and durability. The material of the support member 30 includes stainless steel, so that the corrosion resistance, heat resistance, and durability of the support member 30 are good, and the support member 30 can better adapt to the environment inside the battery cell 100, which is conducive to improving the service life of the support member 30 inside the battery cell 100, thereby improving the service life and safety performance of the battery cell 100.

[0125] The support member 30 is made of different materials, and has different bending strengths and elastic moduli. In some embodiments, the bending strength of the support member 30 is H, 30MPa≤H≤300MPa.

[0126] Bending strength refers to the ability of the support member 30 to resist bending without breaking. For example, H can be 30MPa, 50MPa, 70MPa, 90MPa, 100MPa, 120MPa, 140MPa, 160MPa, 180MPa, 200MPa, 200MPa, 220MPa, 240MPa, 260MPa, 280MPa, 300MPa, etc.

[0127] By H≥30MPa, the support member 30 has a higher anti-deformation ability, so that the support member 30 plays a better supporting and reinforcing role on the first end 31, thereby enhancing the anti-deformation ability of the first section 211, so that the inner ring layer A1 of the first pole piece 21 has a strong anti-deformation ability, reducing the risk of central collapse and deformation of the wound electrode assembly 20, thereby effectively reducing lithium deposition, and improving the safety performance and service life of the battery cell 100. By H≤300MPa, when the anti-deformation ability of the component support member 30 is sufficient, it is avoided to select a support member 30 with too high bending strength, which leads to increased cost and excessive performance of the support member 30. Therefore, 30MPa≤H≤300MPa can not only make the inner ring layer A1 of the first pole piece 21 have a strong anti-deformation ability, reduce the risk of central collapse and deformation of the wound electrode assembly 20, thereby effectively reducing lithium deposition, improving the safety performance and service life of the battery cell 100, but also control the cost of the support member 30 and prevent the support member 30 from having excessive performance.

[0128] Further, in some embodiments of the first aspect of the present application, 200MPa≤H≤300MPa.

[0129] In one or more of the above optional embodiments, 200 MPa≤H≤300 MPa, which can further enhance the strength of the inner ring layer A1 and further reduce the risk of collapse and deformation of the center of the electrode assembly 20.

[0130] In some embodiments, the elastic modulus of the support member 30 is G, 1.5 GPa≤G≤200 GPa.

[0131] The elastic modulus is a measure of the ability of the support member 30 to resist elastic deformation. For example, G can be 1.5 GPa, 5 GPa, 10 GPa, 20 GPa, 40 GPa, 60 GPa, 80 GPa, 100 GPa, 120 GPa, 140 GPa, 160 GPa, 180 GPa, 200 GPa, etc.

[0132] By setting G≥1.5GPa, the elastic deformation capacity of the support member 30 is better, which will cause the inner circle layer A1 of the first pole piece 21 to rebound with a larger diameter, thereby supporting the inner circle layer A1 and reducing the risk of the inner circle layer A1 of the first pole piece 21 collapsing inwards, thereby effectively reducing lithium deposition and improving the safety performance and service life of the battery cell 100. By setting G≤200GPa, when the elastic deformation capacity of the component support member 30 is sufficient, it is avoided to select a support member 30 with too high elastic modulus, which leads to increased cost and excessive performance of the support member 30. Therefore, 1.5GPa≤G≤200GPa can not only reduce the risk of the inner circle layer A1 of the first pole piece 21 collapsing inwards, thereby effectively reducing lithium deposition and improving the safety performance and service life of the battery cell 100, but also control the cost of the support member 30 and prevent the excessive performance of the support member 30.

[0133] Further, in some embodiments of the first aspect of the present application, 100 GPa≤G≤200 GPa.

[0134] In one or more of the above optional embodiments, by limiting 100 GPa≤G≤200 GPa, the elastic deformation ability of the support member 30 is further improved, thereby reducing the risk of the inner circle layer A1 of the first pole piece collapsing inwards.

[0135] When the first pole piece 21 is wound, the support member 30 may also be wound synchronously with the first pole piece 21. The number of windings of the support member 30 may be less than one circle or at least one circle. The support member 30 is wound once for every 360° winding along the winding direction X from the first end 31.

[0136] In some embodiments, the support member 30 is wound along the winding direction X for at least one turn.

[0137] When the number of turns of the support member 30 is an integer, the first end 31 and the second end 32 may be coplanar. For example, the support member 30 is wound around the winding axis P along the winding direction X by one turn, two turns, three turns, etc. The plane passing through the first end 31 is defined as the second reference plane P2, and the plane passing through the second end 32 is defined as the third reference plane P3. When the first end 31 and the second end 32 are coplanar, the second reference plane P2 and the third reference plane P3 are the same plane. Figure 2 FIG. 3 shows a state where the support member 30 is wound one circle.

[0138] When the number of turns of the support member 30 is non-integer, the first end 31 and the second end 32 are not coplanar, that is, the second reference plane P2 and the third reference plane P3 are different planes, and there is a distance between the second reference plane P2 and the third reference plane P3 along the winding direction X. Exemplarily, the support member 30 is wound around the winding axis P in the winding direction X by 0.5 turns, 1.5 turns, 2.5 turns, 3.5 turns, etc. Figure 7 , it shows the case where the number of turns of the support member 30 is not an integer.

[0139] By winding the support member 30 at least one circle along the winding direction X, the inner circle layer A1 of the first pole piece 21 has a stronger deformation resistance, further reducing the risk of central collapse and deformation of the wound electrode assembly 20, thereby effectively reducing lithium plating and improving the safety performance and service life of the battery cell 100.

[0140] like Figure 2 , Figure 3 As shown, in some embodiments, when viewed along a direction perpendicular to the winding axis P of the electrode assembly 20 and passing through the first end 31 , the first end 31 and the second end 32 are coplanar.

[0141] It can be understood that the number of turns of the support member 30 is an integer. The second reference plane P2 and the third reference plane P3 are the same plane.

[0142] By observing along the winding axis P of the vertical electrode assembly 20 and through the direction of the first end 31, the first end 31 and the second end 32 are coplanar, and the number of turns of the support member 30 around the winding axis P is a full turn, which is convenient for controlling the length of the support member 30 along the winding direction X and the number of turns of the support member 30.

[0143] In some embodiments, the support member 30 is wound at least twice along the winding direction X. By winding the support member 30 at least twice along the winding direction X, the deformation resistance of the inner ring layer A1 of the first pole piece 21 is further enhanced, and the risk of central collapse and deformation of the wound electrode assembly 20 is further reduced, thereby effectively reducing lithium plating and improving the safety performance and service life of the battery cell 100. Figure 8 FIG. 3 shows a situation where the support member 30 is wound twice.

[0144] like Figure 3 As shown, in some embodiments, along the winding direction X, the support member 30 does not exceed the first position Q.

[0145] The second end 32 of the support member 30 may be flush with or have a distance from the first position Q. The support member 30 does not extend beyond the first position Q. Since the first position Q is aligned with the second winding start end 221, the support member 30 does not extend beyond the second winding start end 221 along the winding direction X. Thus, along the winding direction X, the support member 30 does not extend between the second section 212 and the second pole piece 22.

[0146] Therefore, along the winding direction X, the support member 30 does not exceed the first position Q, reducing the risk of the support member 30 extending to between the first pole piece 21 and the second pole piece 22 and piercing the isolation membrane 23 to cause a short circuit in the battery cell 100. It can also alleviate the problem of the battery cell 100 having a larger structural size of the electrode assembly 20 due to the provision of the support member 30, and alleviate the size differences of various parts of the electrode assembly 20, thereby reducing the risk of uneven force on the pole pieces due to the expansion of the electrode assembly 20 during the cycle of the battery cell 100.

[0147] Specifically, Figure 3 As shown, in an embodiment where the support member 30 does not exceed the first position Q along the winding direction X, the support member 30 has a second end 32 opposite to the first end 31 along the winding direction X, and the second end 32 is spaced from the first position Q.

[0148] Along the winding direction X, the second end 32 is spaced from the first position Q, leaving a margin for misalignment between the first pole piece 21 and the second pole piece 22 due to expansion of the electrode assembly 20 during the cycle of the battery cell 100, thereby reducing the risk of the support member 30 extending to between the first pole piece 21 and the second pole piece 22 after the electrode assembly 20 expands, thereby reducing the risk of the support member 30 extending to between the first pole piece 21 and the second pole piece 22 and piercing the isolation membrane 23 to cause a short circuit in the battery cell 100, thereby further improving the safety performance of the battery cell 100.

[0149] like Figure 3 As shown, along the winding direction X, the distance between the second end 32 and the first position Q is K, and 0.5 mm≤K≤15 mm.

[0150] For example, K can be 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, etc.

[0151] By setting K≥0.5mm, there is a sufficient distance between the second end 32 and the first position Q in the winding direction X, thereby leaving enough margin for the misalignment between the first pole piece 21 and the second pole piece 22 caused by the expansion of the electrode assembly 20 during the cycle of the battery cell 100, thereby reducing the risk of the support member 30 extending between the first pole piece 21 and the second pole piece 22 after the electrode assembly 20 expands, thereby reducing the risk of the support member 30 extending between the first pole piece 21 and the second pole piece 22 after the electrode assembly 20 expands and piercing the isolation film 23, causing the battery cell 100 to short-circuit, further improving the safety performance of the battery cell 100. By setting K≤15mm, it is avoided that the distance between the second end 32 and the first position Q in the winding direction X is too large, resulting in insufficient support strength of the support member 30 for the first section 211 and the inability to effectively improve the problem of collapse of the center hole of the wound electrode assembly 20. Therefore, 0.5mm≤K≤15mm can not only reduce the risk of the support member 30 extending to between the first pole piece 21 and the second pole piece 22 after the electrode assembly 20 expands and puncturing the isolation membrane 23, thereby causing a short circuit in the battery cell 100, further improving the safety performance of the battery cell 100, but also effectively improve the problem of collapse of the center hole of the wound electrode assembly 20.

[0152] like Figure 2 , Figure 3 As shown, in some embodiments, when viewed along a direction perpendicular to the winding axis P of the electrode assembly 20 and passing through the second winding start end 221 , the first end 31 and the second winding start end 221 are not coplanar.

[0153] That is, the second reference plane P2 and the first reference plane P1 are different planes.

[0154] The first end 31 and the second winding starting end 221 are not coplanar, which helps to alleviate the problem of larger structural dimensions of the electrode assembly 20 due to the provision of the support member 30 in the battery cell 100, and alleviate the size differences of various parts of the electrode assembly 20, thereby reducing the risk of uneven force on the electrode sheet due to expansion of the electrode assembly 20 during the cycle of the battery cell 100.

[0155] like Figure 2 , Figure 3 As shown, in some embodiments, when viewed along a direction perpendicular to the winding axis P of the electrode assembly 20 and passing through the second winding start end 221 , the second end 32 and the second winding start end 221 are not coplanar.

[0156] That is, the third reference plane P3 and the first reference plane P1 are different planes.

[0157] The second end 32 and the second winding starting end 221 are not coplanar, which helps to alleviate the problem of larger structural dimensions of the electrode assembly 20 due to the provision of the support member 30 in the battery cell 100, and alleviate the size differences of various parts of the electrode assembly 20, thereby reducing the risk of uneven force on the electrode sheets due to expansion of the electrode assembly 20 during the cycle of the battery cell 100.

[0158] like Figure 4 , Figure 5 As shown, in some embodiments, along the winding direction X, the length of the support member 30 is W, 3mm≤W≤32mm.

[0159] When the first pole piece 21 is in the unfolded state, the length direction of the first pole piece 21 and the length direction of the support member 30 correspond to the winding direction X when the first pole piece 21 and the support member 30 are in the wound state. Therefore, when the support member 30 is in the unfolded state, W is the distance between the first end 31 and the second end 32 in the length direction of the first pole piece 21.

[0160] Exemplarily, W may be 3 mm, 5 mm, 7 mm, 9 mm, 10 mm, 11 mm, 12 mm, 14 mm, 16 mm, 18 mm, 20 mm, 22 mm, 24 mm, 26 mm, 28 mm, 30 mm, 32 mm, etc.

[0161] The battery cell 100 further includes a second pole tab 222, which is electrically connected to the second pole piece 22. When the first pole tab 214 is electrically connected to the housing 10, the second pole tab 222 can be electrically connected to the electrode terminal 13. When the first pole tab 214 is electrically connected to the electrode terminal 13, the second pole tab 222 can be electrically connected to the housing 10.

[0162] For example, in conjunction with reference Figure 1 , Figure 2 , Fig. 9 , Fig.10Along the extension direction of the winding axis P, the shell 11 has a bottom wall 112 opposite to the cover body 12.

[0163] The second electrode tab 222 is welded to the bottom wall 112 , and the first electrode tab 214 is welded to the electrode terminal 13 .

[0164] Along the extension direction of the winding axis P, the support member 30 extends beyond one end of the first pole piece 21 close to the bottom wall 112 and one end of the second pole piece 22 close to the bottom wall 112 , and one end of the support member 30 close to the bottom wall 112 abuts against the surface of the second pole ear 222 facing the electrode assembly 20 .

[0165] In a conventional button battery, one of the tabs needs to be connected to the bottom wall 112 of the shell 11. A columnar support column is passed through the middle of the battery cell 100 to support the tab electrically connected to the bottom wall 112 and the surface of the electrode assembly 20 facing the extension direction of the winding axis P. In this way, the tab and the bottom wall 112 of the shell 11 can be welded from the outside of the shell 11. When the second tab 222 is welded to the bottom wall 112, the support member 30 is set to extend beyond one end of the first pole piece 21 close to the bottom wall 112 and the second pole piece 21 close to the bottom wall 112. The pole piece 22 is close to one end of the bottom wall 112, and the end of the support member 30 is close to the bottom wall 112 and abuts against the surface of the second pole ear 222 facing the electrode assembly 20, which can directly support the second pole ear 222 so that the bottom wall 112 and the second pole ear 222 can maintain contact in the extension direction of the winding axis P, which is convenient for welding the second pole ear 222 and the bottom wall 112, and can also avoid adding other structures such as support columns to keep the bottom wall 112 and the second pole ear 222 in contact during the manufacturing process, which makes the inner hole of the battery cell 100 larger.

[0166] In addition, when the elastic modulus is 200 MPa≤H≤300 MPa, or the bending strength is 30 MPa≤H≤300 MPa, the supporting effect of the supporting member 30 can be better.

[0167] In some embodiments, the diameter of the central hole M of the electrode assembly 20 is 0.6 mm to 2.3 mm.

[0168] The central hole M is a central through hole formed by the winding needle volume during the winding process of the electrode assembly 20. In one embodiment, the hole wall surface of the central hole M may be the surface of the separator 23.

[0169] For example, the diameter of the center hole can be 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1 mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9 mm, 2mm, 2.1mm, 2.2mm, 2.3mm, etc.

[0170] By extending along the winding axis P, the support member 30 exceeds one end of the first pole piece 21 close to the bottom wall 112 and one end of the second pole piece 22 close to the bottom wall 112, and one end of the support member 30 close to the bottom wall 112 abuts against the surface of the second pole ear 222 facing the electrode assembly 20, so that the center hole of the electrode assembly 20 can be made smaller, which can be less than 2.3 mm. The larger than 0.6 mm is caused by the winding needle of the inner circle.

[0171] The battery cells 100 with different elastic moduli and bending strengths of the support members 30 are tested to obtain the inner circle layer collapse degree of the corresponding battery cells 100. For Table 1, other parameters and structures of the battery cells 100 in the embodiments in Table 1 are the same except for the parameters in Table 1.

[0172] The collapse degree of the inner coil layer of the electrode assembly 20 of the battery cell 100 close to the winding axis can be tested according to the following method:

[0173] The lithium-ion battery cells in each embodiment (battery cell 100 provided with a support 30) were subjected to a charge and discharge cycle test in a 25°C constant temperature box, with a charge and discharge voltage range of 2.5V to 4.2V, charged to 4.2V at a 2C constant current, then charged to 0.05C at a 4.2V constant voltage and left to stand for 5 minutes, and then discharged to 2.5V at a 6C constant current, and the above charge and discharge process was repeated for 600 cycles. After the battery cell 100 was fully charged, a CT scan was performed to measure the degree of collapse. Among them, the degree of collapse is: in the collapsed area, the distance between the most protruding position of the innermost circle of the electrode assembly 20 in the direction close to the winding center and the circle layer closest to the winding axis without indentation is measured 5 times and the average value is taken. The test structure in Table 1 is obtained.

[0174] Table 1

[0175]

[0176] As can be seen from Table 1, in Examples 1 to 8, as the elastic modulus G of the support member 30 gradually increases, the degree of collapse of the inner circle of the battery cell gradually decreases. Especially after the elastic modulus of the support member 30 reaches 1.5 GPa, the degree of collapse of the inner circle is significantly reduced relative to the degree of collapse of the inner circle of the support member 30 with an elastic modulus of 1 GPa. Therefore, G ≥ 1.5 GPa, so that the degree of collapse of the inner circle of the battery cell 100 is smaller, and the safety and service life of the battery cell are smaller. As can be seen from Examples 7 and 8, when the elastic modulus of the support member 30 exceeds 200 GPa, as the elastic modulus of the support member 30 increases, the degree of collapse of the inner circle is not significantly improved, and the use of a support member 30 with a larger elastic modulus will lead to an increase in cost. Therefore, G ≤ 200 GPa can control the cost of the battery cell 100. In summary, 1.5GPa≤G≤200GPa can not only reduce the degree of inward collapse of the inner layer of the first electrode, thereby effectively reducing lithium plating, improving the safety performance and service life of the battery cell, but also control the production cost of the battery cell.

[0177] In Examples 9 to 18, as the bending stiffness H of the support member 30 gradually increases, the degree of collapse of the inner ring of the battery cell gradually decreases. In particular, after the bending strength of the support member 30 reaches 30 MPa, the degree of collapse of the inner ring is significantly reduced relative to the degree of collapse of the inner ring of the support member 30 with a bending strength of 20 MPa. Therefore, H ≥ 30 MPa, so that the degree of collapse of the inner ring layer of the battery cell 100 is smaller, and the safety and service life of the battery cell are smaller. It can be seen from Examples 17 and 18 that when the bending strength of the support member 30 exceeds 300 GPa, as the bending strength of the support member 30 increases, the degree of collapse of the inner ring is not significantly improved, and the use of a support member 30 with a larger bending strength will lead to an increase in cost. Therefore, H ≤ 300 MPa can control the cost of the battery cell 100. In summary, 30MPa≤H≤300MPa can not only reduce the degree of inward collapse of the inner layer of the first electrode, thereby effectively reducing lithium plating, improving the safety performance and service life of the battery cell, but also control the production cost of the battery cell.

[0178] By testing the battery cells 100 with different elastic moduli and bending strengths of the support member 30, the inner circle layer collapse degree and short circuit failure rate of the corresponding battery cell 100 can be obtained. The test method can refer to the above method and will not be repeated here. For Table 2, the parameters and structures other than those in Table 2 in the battery cells 100 in the embodiment in Table 2 are the same.

[0179] Table 2

[0180] K Short circuit defect rate Inner circle collapse Embodiment 19 0.3mm 2 / 5 0.049mm Embodiment 20 0.5mm 1 / 5 0.05mm Embodiment 21 1mm 0 0.15mm Embodiment 22 2mm 0 0.2mm Embodiment 23 5mm 0 0.25mm Embodiment 24 8mm 0 0.29mm Embodiment 25 10mm 0 0.33mm Embodiment 26 12mm 0 0.4mm Embodiment 27 15mm 0 0.5mm Embodiment 28 16mm 2 / 5 1.5mm

[0181] It can be seen from Table 2 that as the distance between the second end 32 and the first position Q along the winding direction increases, the degree of collapse of the inner circle of the battery cell 100 gradually increases, and the short circuit defect rate of the battery cell 100 shows a trend of first increasing and then decreasing. When the distance K between the second end 32 and the first position Q along the winding direction is less than 0.5 mm, since the distance between the second end 32 and the first position Q along the winding direction is too small, after the battery cell 100 is cycled, the support member 30 is easy to extend between the first pole piece and the second pole piece, resulting in an increased risk of short circuit of the battery cell. When the distance K between the second end 32 and the first position Q along the winding direction is greater than 15 mm, the first section 211 between the second end 32 and the first position Q is not supported by the support member 30, and the anti-deformation ability is weak, so that the risk of collapse of the first section 211 between the second end 32 and the first position Q is greater, thereby increasing the risk of short circuit of the battery cell 100. Therefore, 0.5mm≤K≤15mm can not only reduce the risk of the support extending to between the first pole piece and the second pole piece after the electrode assembly expands and puncturing the isolation membrane to cause a short circuit in the battery cell, further improving the safety performance of the battery cell, but also effectively improve the problem of collapse of the center hole of the wound electrode assembly.

[0182] The embodiment of the present application further provides an electric device, the electric device comprising the battery cell 100 provided by any of the above embodiments. The battery cell 100 provides electric energy for the electric device to operate.

[0183] The battery cell 100 provided in any of the above embodiments has higher safety performance and longer service life, and the electrical equipment powered by the battery cell 100 has better power reliability.

[0184] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes.

Claims

1. A battery cell, characterized in that: include: A wound electrode assembly, comprising a first pole piece and a second pole piece with opposite polarities, the first pole piece and the second pole piece are stacked and wound along a winding direction to form a winding structure, the first pole piece has a first winding starting end, the second pole piece has a second winding starting end, the first pole piece comprises a first section and a second section arranged continuously along the winding direction, the first section and the second section are connected at a first position, in a direction perpendicular to the winding axis of the electrode assembly and passing through the second winding starting end, the first position is aligned with and adjacent to the second winding starting end, and is located on a side of the second winding starting end away from the winding axis, and an end of the first section away from the first position is the first winding starting end; a support member connected to a surface of the first section facing the winding axis; Wherein, along the winding direction, the support member has a first end close to the first winding starting end, and along the opposite direction of the winding direction, the first section exceeds the first end.

2. The battery cell according to claim 1, characterized in that: The first section includes a first current collecting layer and a first active material layer. Along the thickness direction of the first current collecting layer, the first current collecting layer has a first surface facing away from the winding axis and a second surface facing the winding axis. The first surface is provided with the first active material layer, and the support member is provided on the second surface.

3. The battery cell according to claim 2, characterized in that: The support member is bonded or welded to the second surface.

4. The battery cell according to claim 1, characterized in that: The supporting member is a metal member.

5. The battery cell according to claim 4, characterized in that: The material of the support member includes stainless steel.

6. The battery cell according to claim 1, characterized in that: Along the winding direction, the support member does not exceed the first position.

7. The battery cell according to claim 6, characterized in that: Along the winding direction, the support member has a second end opposite to the first end, and the second end is spaced apart from the first position.

8. The battery cell according to claim 7, characterized in that: Along the winding direction, a distance between the second end and the first position is K, and 0.5 mm≤K≤15 mm.

9. The battery cell according to any one of claims 1 to 8, characterized in that: The bending strength of the support member is H, 30MPa≤H≤300MPa.

10. The battery cell according to claim 9, characterized in that: 200MPa≤H≤300MPa.

11. The battery cell according to any one of claims 1 to 8, characterized in that: The elastic modulus of the support member is G, 1.5 GPa≤G≤200 GPa.

12. The battery cell according to claim 11, characterized in that: 100GPa≤G≤200GPa.

13. The battery cell according to claim 1, characterized in that: Along the opposite direction of the winding direction, the first section includes a first portion extending beyond the first end, and the length of the first portion is L, 0.5 mm≤L≤15 mm.

14. The battery cell according to claim 1, characterized in that: Viewed from a direction perpendicular to the winding axis of the electrode assembly and passing through the second winding start end, the first end and the second winding start end are not coplanar.

15. The battery cell according to claim 1, characterized in that: Along the winding direction, the support member has a second end, and the second end is arranged opposite to the first end; When viewed from a direction perpendicular to the winding axis of the electrode assembly and passing through the second winding start end, the second end and the second winding start end are not coplanar.

16. The battery cell according to claim 1, characterized in that: The support member is wound at least once along the winding direction.

17. The battery cell according to claim 16, characterized in that: Along the winding direction, the support member has a second end, and the second end is arranged opposite to the first end; Viewed along a direction perpendicular to the winding axis of the electrode assembly and passing through the first end, the first end and the second end are coplanar.

18. The battery cell according to claim 16, characterized in that: The support member is wound at least twice along the winding direction.

19. The battery cell according to claim 1, characterized in that: The first pole piece is a negative pole piece, and the second pole piece is a positive pole piece.

20. The battery cell according to claim 1, characterized in that: The battery cell is a button battery.

21. The battery cell according to claim 20, characterized in that: The battery cell comprises a shell, and the electrode assembly is accommodated in the shell; The housing comprises a shell and a cover, the shell has an opening, the cover covers the opening, and along the extension direction of the winding axis, the shell has a bottom wall opposite to the cover; The battery cell also includes a first pole ear and a second pole ear, the first pole ear is electrically connected to the first pole sheet, the second pole ear is electrically connected to the second pole sheet, the second pole ear is welded to the bottom wall, and along the extension direction of the winding axis, the support member exceeds one end of the first pole sheet close to the bottom wall and one end of the second pole sheet close to the bottom wall, and one end of the support member close to the bottom wall abuts against the surface of the second pole ear facing the electrode assembly.

22. The battery cell according to claim 21, characterized in that: The diameter of the central hole of the electrode assembly is 0.6 mm to 2.5 mm.

23. An electrical equipment, characterized in that: Comprising a battery cell according to any one of claims 1-22.

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