Battery cell and electrical device

Abstract

The present application provides a battery cell and an electrical device. The battery cell comprises: a support member; and a wound electrode assembly, the electrode assembly comprising a first electrode sheet and a second electrode sheet. The first electrode sheet comprises a first section and a second section which are consecutively arranged in a winding direction and are connected at a first position. The first position is aligned with and adjacent to a second winding start end of the second electrode sheet, and is located on the side of the second winding start end facing away from a winding axis. The end of the first section away from the first position is a first winding start end. The support member is connected to the surface of the first section facing the winding axis. In the direction opposite to the winding direction, the first section exceeds the first end of the support member close to the first winding start end. The support member serves the function of supporting and reinforcing the first section, so that the risk of collapse and deformation at the center of the electrode assembly is reduced, thereby improving the safety performance and service life of the battery cell. Accurate positioning in the winding direction is not required during arrangement of the support member, so that the difficulty of processing is reduced, and the arrangement of the support member is facilitated.

Description

Battery cells and electrical equipment

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese patent application 2024115701277 entitled “Battery Cell and Electrical Equipment”, filed on November 5, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of battery technology, and more specifically, to a battery cell and an electrical device. Background Technology

[0004] With the rapid development of new energy technologies, battery cells have been widely used in electronic devices, electric vehicles, electric two-wheelers, power tools, and other fields. As the application of battery cells becomes more widespread, higher requirements are being placed on their safety. Summary of the Invention

[0005] This application provides a battery cell and an electrical device to improve the safety performance of the battery cell.

[0006] In a first aspect, embodiments of this application provide a battery cell, which includes a support member and a wound electrode assembly. The electrode assembly includes a first electrode and a second electrode with opposite polarities. The first electrode and the second electrode are stacked and wound along a winding direction to form a wound structure. The first electrode has a first winding start end, and the second electrode has a second winding start end. The first electrode includes a first segment and a second segment continuously arranged along the winding direction. The first segment and the second segment are connected at a first position. In a direction perpendicular to the winding axis of the electrode assembly and passing through the second winding start end, the first position is aligned with and adjacent to the second winding start end, and is located on the side of the second winding start end away from the winding axis. The end of the first segment away from the first position is the first winding start end. The support member is connected to the surface of the first segment facing the winding axis. Along the winding direction, the support member has a first end close to the first winding start end, and in the opposite direction of the winding direction, the first segment extends beyond the first end.

[0007] In one or more of the above optional embodiments, the end of the first segment of the first electrode sheet furthest from the second segment is the first winding start end. The first segment is wound to form an inner ring layer. A support member is provided on the first segment of the first electrode sheet, which provides support and reinforcement, thereby enhancing the first segment's resistance to deformation. This results in a stronger resistance to deformation for the inner ring layer of the first electrode sheet, reducing the risk of central collapse and deformation in the wound electrode assembly, effectively reducing lithium plating, and improving the safety performance and lifespan of the battery cell. In the opposite direction of the winding direction, if the first segment extends beyond the support member and is close to the first winding start end, the first end of the support member and the first winding start end are not aligned. Therefore, precise positioning in the winding direction is not required when setting the support member, reducing process difficulty and facilitating support member placement. Furthermore, in the opposite direction of the winding direction, if the first segment extends beyond the support member and is close to the first winding start end, the support member does not completely cover the surface of the first segment facing the winding axis, reducing the amount of support member used and helping to alleviate the problem of increased battery cell weight caused by the installation of support members.

[0008] In some embodiments of the first aspect of this application, the first segment includes a first current collector layer and a first active material layer. Along the thickness direction of the first current collector layer, the first current collector layer has a first surface 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.

[0009] In one or more of the above optional embodiments, the support member is connected to the second surface, so at least a portion of the second surface is free of the first active material layer, reducing the amount of first active material layer on the first electrode that does not contribute to its capacity, thereby reducing the waste of active material. Connecting the support member to the second surface also reduces the risk of powder shedding from the first active material layer due to the support member, further improving the safety performance of the battery cell.

[0010] In some embodiments of the first aspect of this application, the support is bonded or welded to the second surface.

[0011] In one or more of the above optional embodiments, the support member is bonded or welded to the second surface, which makes it simpler to set the support member in the first segment, and the support member and the second surface have better connection strength, thereby improving the connection stability of the support member.

[0012] In some embodiments of the first aspect of this application, the support is a metal component.

[0013] In one or more of the above optional embodiments, the support is a metal part, which has better strength and rigidity, making the inner ring of the first electrode sheet more resistant to deformation, further reducing the risk of collapse and deformation of the center of the wound electrode assembly, thereby further effectively reducing lithium plating and improving the safety performance and service life of the cell.

[0014] In some embodiments of the first aspect of this application, the material of the support includes stainless steel.

[0015] In one or more of the above optional embodiments, stainless steel has advantages such as high corrosion resistance, heat resistance, and durability. The support component is made of stainless steel, which makes the support component have good corrosion resistance, heat resistance, and durability. The support component can better adapt to the internal environment of the battery cell, which is conducive to improving the service life of the support component inside the battery cell, thereby improving the service life and safety performance of the battery cell.

[0016] In some embodiments of the first aspect of this application, the support does not extend beyond the first position along the winding direction.

[0017] In one or more of the above optional embodiments, the support does not extend beyond the first position along the winding direction, which reduces the risk of the support extending between the first and second electrodes and puncturing the separator, thus causing a short circuit in the battery cell. It can also alleviate the problem of the large structural size of the electrode assembly caused by the support in the battery cell, and alleviate the size difference of each part of the electrode assembly, thereby reducing the risk of uneven stress on the electrode plates caused by the expansion of the electrode assembly during the battery cell cycle.

[0018] In some embodiments of the first aspect of this 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.

[0019] In one or more of the above optional embodiments, the second end is spaced apart from the first position along the winding direction to allow for misalignment between the first and second electrodes caused by the expansion of the electrode assembly during cell cycling. This reduces the risk of the support extending between the first and second electrodes after the electrode assembly expands, thereby reducing the risk of the support puncturing the separator and causing a short circuit in the cell after extending between the first and second electrodes, and further improving the safety performance of the cell.

[0020] In some embodiments of the first aspect of this application, the distance between the second end and the first position along the winding direction is K, where 0.5mm≤K≤15mm.

[0021] In one or more of the above optional embodiments, by setting K ≥ 0.5 mm, sufficient distance is maintained between the second end and the first position in the winding direction. This provides ample leeway for misalignment between the first and second electrodes caused by the expansion of the electrode assembly during cell cycling. This reduces the risk of the support extending between the first and second electrodes after expansion, thereby reducing the risk of the support puncturing the separator and causing a short circuit, further improving the cell's safety performance. By setting K ≤ 15 mm, the distance between the second end and the first position in the winding direction is avoided from being too large, which would result in insufficient support strength for the first segment and fail to effectively address the problem of collapse of the center hole in the wound electrode assembly. Therefore, 0.5 mm ≤ K ≤ 15 mm not only reduces the risk of the support extending between the first and second electrodes and puncturing the separator, thus improving the cell's safety performance, but also effectively addresses the problem of collapse of the center hole in the wound electrode assembly.

[0022] In some embodiments of the first aspect of this application, the bending strength of the support member is H, where 30MPa≤H≤300MPa.

[0023] In one or more of the above optional embodiments, H ≥ 30 MPa ensures high resistance to deformation of the support component, thereby providing better support and reinforcement for the first section. This enhances the first section's resistance to deformation, giving the inner ring of the first electrode a strong resistance to deformation, reducing the risk of central collapse deformation in the wound electrode assembly, effectively reducing lithium plating, and improving the cell's safety performance and lifespan. With H ≤ 300 MPa, given sufficient resistance to deformation of the component support, it avoids selecting support components with excessively high bending strength, which would increase costs and lead to over-performance. Therefore, 300 MPa ≤ H ≤ 300 MPa ensures that the inner ring of the first electrode has strong resistance to deformation, reducing the risk of central collapse deformation in the wound electrode assembly, thus effectively reducing lithium plating, improving the cell's safety performance and lifespan, while also controlling the cost of the support component and preventing over-performance.

[0024] In some embodiments of the first aspect of this application, 200 MPa ≤ H ≤ 300 MPa.

[0025] In one or more of the above optional embodiments, 200 MPa ≤ H ≤ 300 MPa can further enhance the strength of the inner ring layer and reduce the risk of collapse and deformation at the center of the electrode assembly. In some embodiments of the first aspect of this application, the elastic modulus of the support is G, where 1.5 GPa ≤ G ≤ 200 GPa.

[0026] In one or more of the above optional embodiments, a value of G ≥ 1.5 GPa ensures good elastic deformation capability of the support component, causing the inner ring of the first electrode to rebound with an increased diameter. This supports the inner ring, reducing the risk of inward collapse of the inner ring, effectively reducing lithium plating and improving the safety performance and lifespan of the cell. A value of G ≤ 200 GPa avoids using support components with excessively high elastic modulus, which would increase costs and lead to over-performance. Therefore, a value of 1.5 GPa ≤ G ≤ 200 GPa not only reduces the risk of inward collapse of the inner ring of the first electrode, effectively reducing lithium plating and improving the safety performance and lifespan of the cell, but also controls the cost of the support component and prevents over-performance.

[0027] In some embodiments of the first aspect of this application, 100GPa≤G≤200GPa.

[0028] In one or more of the above optional embodiments, by limiting 100GPa≤G≤200GPa, the elastic deformation capacity of the support is further improved, reducing the risk of the inner ring of the first electrode collapsing inward.

[0029] In some embodiments of the first aspect of this application, in the opposite direction to the winding direction, the first segment includes a first portion extending beyond the first end, the length of the first portion being L, 0.5mm≤L≤15mm.

[0030] In one or more of the above optional embodiments, by using L≥0.5mm, the size of the portion of the first segment extending beyond the first end in the opposite direction of the winding direction is sufficiently large, making it easier to install the support member. By using L≤15mm, the problem of reduced cell energy density caused by the first segment extending beyond the first end in the opposite direction of the winding direction is alleviated. Therefore, 0.5mm≤L≤15mm not only facilitates the installation of the support member but also alleviates the problem of reduced cell energy density caused by the first segment extending beyond the first end in the opposite direction of the winding direction.

[0031] In some embodiments of the first aspect of this application, when viewed along the winding axis of the vertical electrode assembly and through the direction of the second winding start end, the first end and the second winding start end are not coplanar.

[0032] In one or more of the above optional embodiments, the first end and the second winding start end are not coplanar, which helps to alleviate the problem of large structural size of the electrode assembly caused by the setting of support members in the battery cell, and to alleviate the size difference of each part of the electrode assembly, thereby reducing the risk of uneven stress on the electrode sheet caused by the expansion of the electrode assembly during the battery cell cycle.

[0033] In some embodiments of the first aspect of this application, the support member has a second end along the winding direction, the second end being disposed opposite to the first end; when viewed along the winding axis of the vertical electrode assembly and through the direction of the second winding start end, the second end and the second winding start end are not coplanar.

[0034] In one or more of the above optional embodiments, the second end and the second winding start end are not coplanar, which helps to alleviate the problem of large structural size of the electrode assembly caused by the setting of support members in the battery cell, and to alleviate the size difference of each part of the electrode assembly, thereby reducing the risk of uneven stress on the electrode sheet caused by the expansion of the electrode assembly during the battery cell cycle.

[0035] In some embodiments of the first aspect of this application, the support member is wound at least one turn in the winding direction.

[0036] In one or more of the above optional embodiments, by winding the support member at least one turn along the winding direction, the inner layer of the first electrode sheet has stronger resistance to deformation, 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 cell.

[0037] In some embodiments of the first aspect of this application, the support member has a second end along the winding direction, the second end being disposed opposite to the first end; when viewed along the winding axis of the vertical electrode assembly and through the first end, the first end and the second end are coplanar.

[0038] In one or more of the above optional embodiments, if the first end and the second end are coplanar when viewed along the winding axis of the vertical electrode assembly and passing through the first end, then the number of turns of the support member around the winding axis is a full turn, which facilitates control of the length of the support member along the winding direction and the number of turns of the support member.

[0039] In some embodiments of the first aspect of this application, the support is wound at least two turns in the winding direction.

[0040] In one or more of the above optional embodiments, by winding the support member at least two turns along the winding direction, the deformation resistance of the inner layer of the first electrode sheet 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 cell.

[0041] In some embodiments of the first aspect of this application, the first electrode is a negative electrode and the second electrode is a positive electrode.

[0042] In one or more of the above optional embodiments, the first electrode is a negative electrode and the second electrode is a positive electrode. The first section of the negative electrode forms the inner ring of the electrode assembly, which is beneficial for the cell to have a higher energy density.

[0043] In some embodiments of the first aspect of this application, the battery cell is a button cell.

[0044] In some embodiments of the first aspect of this application, the battery cell includes a housing and an electrode assembly housed within the housing; the housing includes a casing and a cover, the casing having an opening and the cover sealing the opening, and the casing having a bottom wall opposite the cover along the extension direction of the winding axis;

[0045] The battery cell also includes a first tab and a second tab. The first tab is electrically connected to the first electrode plate, and the second tab is electrically connected to the second electrode plate. The second tab is welded to the bottom wall. Along the extension direction of the winding axis, the support extends beyond the end of the first electrode plate near the bottom wall and the end of the second electrode plate near the bottom wall. The end of the support near the bottom wall abuts against the surface of the second tab facing the electrode assembly.

[0046] In one or more of the above optional embodiments, in a traditional button cell, one of the tabs needs to be connected to the bottom wall of the casing. By passing a columnar support post through the middle of the cell and pressing against the surface of the tab electrically connected to the bottom wall facing the electrode assembly in the extension direction of the winding axis, it is possible to weld the second tab to the bottom wall of the casing from the outside of the casing. When the second tab is welded to the bottom wall, by setting the support member to extend beyond the end of the first electrode near the bottom wall and the end of the second electrode near the bottom wall, and the end of the support member near the bottom wall abutting against the surface of the second tab facing the electrode assembly, it can directly support the second tab, so that the bottom wall and the second tab remain in contact in the extension direction of the winding axis, which facilitates the welding of the second tab to the bottom wall and avoids adding support posts or other structures during the manufacturing process to keep the bottom wall and the second tab in contact, resulting in a larger inner hole of the cell.

[0047] In some embodiments of the first aspect of this application, the diameter of the central hole of the electrode assembly is 0.6 mm to 2.3 mm.

[0048] In one or more of the above optional embodiments, by extending the support member beyond the end of the first electrode near the bottom wall and the end of the second electrode near the bottom wall along the extension direction of the winding axis, and with the end of the support member near the bottom wall abutting against the surface of the second electrode ear facing the electrode assembly, the center hole of the electrode assembly can be made smaller, less than 2.3 mm, while the larger than 0.6 mm is due to the winding needle of the inner ring.

[0049] Secondly, embodiments of this application provide an electrical device, which includes the battery cells provided in any of the above embodiments.

[0050] In one or more of the above optional embodiments, the battery cell provided by any of the above embodiments has high safety performance and long service life, and the electrical equipment powered by the battery cell has better power reliability. Attached Figure Description

[0051] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope.

[0052] Figure 1 is an exploded view of a battery cell provided in some embodiments of this application;

[0053] Figure 2 is a schematic diagram of the structure of an electrode assembly provided in some embodiments of this application;

[0054] Figure 3 is an enlarged view of point B1 in Figure 2;

[0055] Figure 4 is a schematic diagram of the first electrode of the support member provided in some embodiments of this application, viewed along the thickness direction of the first electrode.

[0056] Figure 5 shows a first electrode plate with a support member provided in some embodiments of this application along the width direction of the first electrode plate;

[0057] Figure 6 is a schematic diagram of the structure of a first pole piece provided with a support member according to some other embodiments of this application;

[0058] Figure 7 is a schematic diagram of the structure of an electrode assembly provided in some other embodiments of this application;

[0059] Figure 8 is a schematic diagram of the structure of an electrode assembly provided in some embodiments of this application;

[0060] Figure 9 is a schematic diagram of the structure of the second electrode provided in some embodiments of this application;

[0061] Figure 10 is a cross-sectional view of a battery cell provided in some embodiments of this application.

[0062] Icons: 100-cell; 10-casing; 11-shell; 111-opening; 112-bottom wall; 12-cover; 13-electrode terminal; 20-electrode assembly; 21-first electrode; 211-first segment; 2111-first current collector 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 segment; 2121-second current collector layer; 213 - First winding start end; 214 - First electrode tab; 22 - Second electrode sheet; 221 - Second winding start end; 222 - Second electrode tab; 23 - Separating 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 electrode sheet; Y - Thickness direction of the first electrode sheet; Z - Width direction of the first electrode sheet; P - Winding axis; P1 - First reference surface; P2 - Second reference surface; P3 - Third reference surface; M - Center hole. Embodiments of the present invention

[0063] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0064] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other.

[0065] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0066] In the description of the embodiments of this application, it should be noted that the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use, or the orientation or positional relationship commonly understood by those skilled in the art. It is only for the convenience of describing this application and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on this application. Furthermore, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0067] Currently, judging from market trends, the application of battery cells is becoming increasingly widespread. Battery cells are widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in power tools, drones, energy storage devices, and many other fields. As the application areas of battery cells continue to expand, the market demand is also constantly increasing, and the requirements for battery cell safety are becoming increasingly stringent.

[0068] For wound-type battery cells, the electrode assembly is a wound structure. After the positive electrode, separator, and negative electrode are wound, a central hole is formed at the center of the electrode assembly. With use, the expansion stress of the negative electrode increases, causing it to expand and compress towards the central hole. This leads to the collapse of the inner layers of the electrode assembly near the central hole. The collapsed electrode near the central hole is prone to wrinkling, resulting in unevenness and groove-like gaps between the electrodes. This hinders ion transport, ultimately leading to lithium plating and reduced cell safety. To alleviate the problem of inner layer collapse, related technologies insert a support pillar into the central hole. However, the central hole contains multiple layers of separator, and inserting the support pillar can easily compress the separator or electrode, causing quality abnormalities. Furthermore, there are tolerance issues between the inserted support pillar and the central hole, resulting in gaps. Therefore, the inner collapse phenomenon still occurs after cycling.

[0069] Based on the above considerations, in order to alleviate the problem that the coils of the electrode assembly near the central hole are prone to collapse, leading to a reduction in the safety performance of the battery cell, this application provides a battery cell. The battery cell includes a support member and a wound electrode assembly. The electrode assembly includes a first electrode and a second electrode with opposite polarities. The first electrode and the second electrode are stacked and wound along the winding direction to form a wound structure. The first electrode has a first winding start end, and the second electrode has a second winding start end. The first electrode includes a first segment and a second segment continuously arranged along the winding direction. The first segment and the second segment are connected at a first position. In the direction perpendicular to the winding axis of the electrode assembly and passing through the second winding start end, the first position is aligned with and adjacent to the second winding start end, and is located outside the second winding start end. The end of the first segment away from the first position is the first winding start end. The support member is connected to the surface of the first segment facing the winding axis of the electrode assembly. In the winding direction, the support member has a first end close to the first winding start end, and in the opposite direction of the winding direction X, the first segment extends beyond the first end.

[0070] The end of the first segment of the first electrode that is furthest from the second segment is the first winding start end. The first segment is wound to form an inner ring layer. The first segment of the first electrode is provided with a support member, which supports and strengthens the first segment, thereby enhancing the deformation resistance of the first segment. This makes the inner ring layer of the first electrode have strong deformation resistance, reducing the risk of collapse and deformation of the center of the wound electrode assembly, thereby effectively reducing lithium plating and improving the safety performance and service life of the cell.

[0071] If the first segment extends beyond the first end of the support member near the first winding start end in the opposite direction of the winding direction, then the first end of the support member and the first winding start end are not aligned. Therefore, when setting up the support member, it is not necessary to accurately position it in the winding direction, which reduces the difficulty of the process and facilitates the setting of the support member.

[0072] The battery cells disclosed in the embodiments of this application can be used, but are not limited to, in electrical equipment such as electric two-wheelers, power tools, drones, and energy storage devices. The battery cells conforming to the operating conditions of this application can also be used as the power supply system for electrical equipment, which helps improve the safety performance of the battery cells.

[0073] This application provides an electrical device that uses battery cells as a power source. The electrical device can be, but is not limited to, electronic devices, power tools, electric vehicles, drones, and energy storage devices. Electronic devices can include mobile phones, tablets, laptops, etc.; power tools can include electric drills, chainsaws, etc.; and electric vehicles can include electric cars, electric motorcycles, electric bicycles, etc.

[0074] As shown in Figures 1 and 2, this application provides a battery cell 100, which includes a housing 10 and an electrode assembly 20; the electrode assembly 20 is housed within the housing 10.

[0075] The outer casing 10 forms a receiving space. The receiving space can be used to house the electrode assembly 20, electrolyte, etc. The outer casing 10 can be a rigid shell, such as a steel shell or an aluminum shell, forming a steel-shelled battery cell or an aluminum-shelled battery cell. The outer casing 10 can also be formed of a softer material, such as an aluminum-plastic film or a steel-plastic film, forming a pouch cell.

[0076] The housing 10 may include a housing 11 and a cover 12. The housing 11 has an opening 111 at at least one end, and the cover 12 is used to seal the opening 111 of the housing 11, so that the housing 11 and the cover 12 together define an accommodating space. Specifically, as shown in Figures 1 and 9, along the extension direction of the winding axis P, the housing 11 has a bottom wall 112 opposite to the cover 12. Electrode terminals 13 are insulatedly disposed on the cover 12. The electrode terminals 13 may also be referred to as poles.

[0077] The electrode assembly 20 includes a separator 23, a first electrode 21, another separator 23, and a second electrode 22.

[0078] The first electrode 21 and the second electrode 22 have opposite polarities, meaning that one of the first electrode 21 and the second electrode 22 is the positive electrode, and the other is the negative electrode. As shown in Figure 2, the first electrode 21 is the negative electrode, and the second electrode 22 is the positive electrode.

[0079] The first electrode 21 includes a first current collector and a first active material layer 2112. Along the thickness direction Y of the first electrode, at least one side of the first current collector is disposed on the first active material layer 2112. In embodiments where the first electrode 21 is a positive electrode, the first current collector is a positive current collector, and the first active material layer 2112 is a positive active material layer. At least one side of the positive current collector is disposed on the positive active material layer. For lithium-ion cells, the material of the positive current collector can be aluminum. The positive active material layer can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The positive current collector can be a composite current collector or a non-composite current collector.

[0080] In an embodiment where the first electrode 21 is a negative electrode, the first current collector is a negative current collector, and the first active material layer 2112 is a negative active material layer. The negative active material layer is disposed on at least one side of the negative current collector. For lithium-ion cells, the material of the negative current collector can be copper. The negative current collector can be a composite current collector or a non-composite current collector. The negative active material can be carbon material or silicon material, etc.

[0081] The separator 23 provides insulation between the positive and negative electrode plates, reducing the risk of short circuits in the cell 100. The material of the separator 23 may include polypropylene (PP) or polyethylene (PE), etc.

[0082] The electrode assembly 20 has a wound structure. Specifically, the first electrode 21, the separator 23, the second electrode 22, and another separator 23 are stacked and then wound to form the wound electrode assembly 20; or, the separator 23, the first electrode 21, the other separator 23, and the second electrode 22 are stacked and then wound to form the wound electrode assembly 20. The wound electrode assembly 20 can be a flat wound electrode assembly 20 or a cylindrical electrode assembly 20. In embodiments where the electrode assembly 20 has a cylindrical structure, the battery cell 100 can be a cylindrical battery cell 100 or a columnar battery cell 100. Figure 1 shows the case where the battery cell 100 is a cylindrical battery cell, and Figure 2 shows the case where the electrode assembly 20 has a cylindrical structure. In some embodiments, the battery cell 100 can be a button cell. Figure 1 shows the case where the battery cell 100 is a button cell.

[0083] The innermost electrode of the electrode assembly 20 is a part of the first electrode 21. Understandably, the first electrode 21 is the starting electrode for winding the electrode assembly 20, and the innermost ring of the second electrode 22 is located outside the innermost ring of the first electrode 21. As shown in Figure 2, the first electrode 21 is the negative electrode, and the second electrode 22 is the positive electrode. The first segment 211 of the negative electrode forms the inner ring layer A1 of the electrode assembly 20, which is beneficial for the cell 100 to have a higher energy density.

[0084] The outermost edge of the innermost ring of the first electrode 21 refers to the side of the innermost ring of the first electrode 21 that is away from the winding axis P of the electrode assembly 20. The axis P is the center of the circle formed by the outermost rings of the entire electrode assembly 20 when viewed from above. A certain offset of P is a normal measurement deviation. Alternatively, along the radial direction of the electrode assembly 20, the innermost ring of the second electrode 22 is further away from the winding axis P of the electrode assembly 20 than the innermost ring of the first electrode 21.

[0085] As shown in Figure 4, in some embodiments, a first tab 214 can be provided on the outer ring layer A2 formed by the second segment 212. The first tab 214 and the second current collector layer 2121 can be integrally formed, for example, the first tab 214 of the first electrode 21 is formed by die-cutting the substrate. The first tab 214 and the second current collector layer 2121 can also be separately provided, and the first tab 214 and the second current collector layer 2121 are connected by welding the first tab 214 and the second current collector layer 2121 and by bonding the first tab 214 and the second current collector layer 2121 with conductive adhesive, thereby realizing the electrical connection between the tab and the second current collector layer 2121. In some embodiments, the first tab 214 can be electrically connected to the outer shell 10, for example, by welding or conductive adhesive. In other embodiments, the first tab 214 can also be electrically connected to the electrode terminal 13, for example, by welding or conductive adhesive.

[0086] The first tab 214 protrudes from one end of the first active material layer 2112 along the width direction Z of the first electrode. When the first electrode 21 is in the unfolded state, the width direction Z, the length direction X', and the thickness direction Y of the first electrode are perpendicular to each other.

[0087] As shown in Figures 2-5, in some embodiments, the first electrode 21 includes a first segment 211 and a second segment 212 continuously arranged along the winding direction X, and the first segment 211 and the second segment 212 are connected at a first position Q. The first electrode 21 has a first winding start end 213, which is the starting point of winding the first electrode 21 and also the end of the first electrode 21 closest to the winding axis P in the winding direction X.

[0088] As shown in Figure 5, the first segment 211 includes a first current collector layer 2111 and a first active material layer 2112. The first current collector layer 2111 has a first active material layer disposed on at least one side in its thickness direction. The first current collector layer is a portion of the first current collector along the winding direction X.

[0089] In some embodiments, the first current collection layer 2111 may have a first active material layer 2112 on both sides of a portion of the area; the first current collection layer 2111 may have a 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 segment 211 is a double-sided coated structure, and the other portion of the first segment 211 is a single-sided coated structure.

[0090] In some embodiments, a first active material layer 2112 is provided on both sides of any region of the first current collection layer 2111, that is, the first segment 211 has a double-sided coating structure.

[0091] Of course, the first current collection layer 2111 may also have the first active material layer 2112 on only one side and the first active material layer 2112 not on the other side, that is, the first segment 211 is a single-sided coating structure.

[0092] The end of the first segment 211 furthest from the first position Q is the first winding start end 213. The first segment 211 is wound to form the inner layer A1 of the first electrode 21, which is also the inner layer A1 of the electrode assembly 20.

[0093] As shown in Figure 5, the second segment 212 includes a second current collector layer 2121 and a first active material layer 2112. The second current collector layer 2121 has the first active material layer disposed on at least one side in its thickness direction. The second current collector layer 2121 is another part of the first current collector along the winding direction X.

[0094] In some embodiments, the second current collection layer 2121 may have a first active material layer 2112 on both sides of a portion of the area; the second current collection layer 2121 may have a 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 second segment 212 is a double-sided coated structure and the other portion of the second segment 212 is a single-sided coated structure.

[0095] In some embodiments, a first active material layer 2112 is provided on both sides of any region of the second current collection layer 2121, that is, the second segment 212 is a double-sided coated structure.

[0096] Of course, the second current collection layer 2121 may also have the first active material layer 2112 on only one side and no first active material layer 2112 on the other side, and the second segment 212 is a single-sided coating structure.

[0097] Referring to Figures 2-5, the second segment 212 is wound to form the inner layer A1 of the first electrode 21, and the outer layer A2 formed by the second segment 212 is located outside the inner layer A1 formed by the first segment 211.

[0098] The second electrode 22 has a second winding start end 221, which is the starting point of winding the second electrode 22 and also the end of the second electrode 22 closest to the winding axis P in the winding direction X.

[0099] In this embodiment, as shown in FIG3, in the direction of the winding axis P of the vertical 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.

[0100] Defined as the plane passing through the second winding start end 221, designated as the first reference plane P1, and the position where the first reference plane P1 intersects with the first electrode 21 adjacent to and located outside the second winding start end 221, designated as the first position Q. This ensures that in the 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 located outside the second winding start end 221. Here, "outside the second winding start end 221" refers to the side of the second winding start end 221 that is away from the winding axis P in the direction parallel to the end face of the second winding start end 221 and perpendicular to the winding axis P.

[0101] As shown in Figures 2-5, in some embodiments, the battery cell 100 further includes a support member 30, which is connected to the surface of the first segment 211 facing the winding axis P of the electrode assembly 20.

[0102] The end of the first segment 211 of the first electrode 21 furthest from the second segment 212 is the first winding start end 213. The first segment 211 is wound to form an inner ring layer A1. The first segment 211 of the first electrode 21 is provided with a support member 30, which supports and strengthens the first segment 211, thereby enhancing the deformation resistance of the first segment 211. This makes the inner ring layer A1 of the first electrode 21 have a strong deformation resistance, reducing the risk of collapse and deformation of the center of the wound electrode assembly 20, thereby effectively reducing lithium plating and improving the safety performance and service life of the cell 100.

[0103] The surface of the first segment 211 facing the winding axis P can be the surface of the first active material layer 2112, the surface of the first current collector layer 2111, or a part of the surface of the first active material layer 2112 and a part of the surface of the first current collector layer 2111.

[0104] As shown in Figures 2-5, along the thickness direction of the first current collector layer 2111, the first current collector layer 2111 has a first surface 21111 and a second surface 21112 facing each other. The first surface 21111 is disposed away from the winding axis P, and the second surface 21112 is disposed facing the winding axis P. The thickness direction of the first current collector layer 2111 is parallel to the thickness direction Y of the first electrode.

[0105] A first active material layer 2112 is provided on the first surface 21111.

[0106] The second surface 21112 can also be provided with a first active material layer 2112. The second surface 21112 is completely covered by the first active material layer 2112. Then the surface of the first segment 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 can be provided on the surface of the first active material layer 2112 of the second surface 21112 facing the winding axis P.

[0107] The second surface 21112 may not have the first active material layer 2112. In this case, the surface of the first segment 211 facing the winding axis P becomes the second surface 21112. The support member 30 can be disposed on the second surface 21112. Without the first active material layer 2112, the first active material layer 2112 on the first electrode 21 is not utilized, thus reducing the waste of active material. The support member 30, connected to the second surface 21112, also reduces the risk of powder shedding from the first active material layer 2112 due to the support member 30, further improving the safety performance of the cell 100.

[0108] The second surface 21112 may have a portion of the first active material layer 2112 disposed thereon, while another portion of the second surface 21112 may not have the first active material layer 2112 disposed thereon. In this case, the surface of the first segment 211 facing the winding axis P is formed by the surface of the second surface 21112 with the first active material layer 2112 facing the winding axis P and a portion of the second surface 21112. In this scenario, the support member 30 can be disposed on the surface of the second surface 21112 with the first active material layer 2112 facing the winding axis P and / or on the area of ​​the second surface 21112 where the first active material layer 21112 is not disposed thereon. The absence of the first active material layer 2112 in a portion of the second surface 21112 reduces the amount of the first active material layer 2112 on the first electrode 21 that does not utilize its capacity, thereby reducing the waste of active material. The support member 30, connected to the second surface 21112, also reduces the risk of powder shedding from the first active material layer 2112 due to the placement of the support member 30, further improving the safety performance of the cell 100.

[0109] In embodiments where at least a portion of the second surface 21112 does not have the first active material layer 2112, the area of ​​the second surface 21112 without the first active material layer 2112 can extend to the first winding start end 213 in the opposite direction of the winding direction X. Exemplarily, as shown in Figures 3 and 4, the second surface 21112 does not have the first active material layer 2112, and the support member 30 is connected to the second surface 21112. As shown in Figure 6, the second surface 21112 includes a first region 211111 and a second region 211112. The first region 211111 has the first active material layer 2112, and the second region 211112 extends to the first winding start end 213 in the opposite direction of the winding direction X. The support member 30 is connected to the second region 211112.

[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 can be bonded together. For example, an adhesive layer can be applied to the support member 30 and the second surface 21112, and the support member 30 and the second surface 21112 can be connected by the adhesive layer. The support member 30 and the second surface 21112 can also be connected by adhesive tape.

[0111] In the embodiment where the support member 30 is connected to the second surface 21112, the support member 30 and the second surface 21112 can be welded together. The welded connection between the support member 30 and the second surface 21112 can be achieved by laser welding, ultrasonic welding, or other methods.

[0112] The support member 30 is bonded or welded to the second surface 21112, which makes it easier to set the support member 30 in the first segment 211, and the support member 30 and the second surface 21112 have good connection strength, thus improving the connection stability of the support member 30.

[0113] In other embodiments, the support member 30 may be disposed on the first segment 211 by means of spraying, coating or the like.

[0114] Along the winding direction X, the support member 30 has a second end 32, which is disposed opposite to the first end 31, that is, the second end 32 and the first end 31 are respectively located at the two ends of the support along the winding direction X.

[0115] Along the winding direction X, the second active material layer closest to the support 30 has a third end 21121 facing the second end 32. The third end 21121 can contact the second end 32 to avoid exposing empty foil between the second end 32 and the third end 21121, thereby reducing the risk of short circuit in the cell 100.

[0116] Along the winding direction X, there may be a gap between the third end 21121 and the second end 32 to reduce the occurrence of problems such as wrinkling of the support 30, peeling of the support 30 from the second surface 21112, and powdering of the second active material layer caused by the support 30 and the first active material layer 2112 being squeezed in the winding direction X during winding.

[0117] The third end 21121 can be the end of the first active material layer 2112 on the side of the second segment 212 facing the winding axis P, opposite to the support member 30 in the winding direction X. Alternatively, the third end 21121 can be the end of the first active material layer 2112 on the side of the first segment 211 facing the winding axis P, opposite to the support member 30 in the winding direction X. Figure 5 shows 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 segment 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 shows 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 segment 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.

[0118] Referring to Figures 3-5, along the winding direction X, the support member 30 has a first end 31 near the first winding start end 213, and in the opposite direction of the winding direction X, the first segment 211 extends beyond the first end 31.

[0119] In the opposite direction of the winding direction X, the first segment 211 extends beyond the support member 30 and approaches the first end 31 of the first winding start end 213. Therefore, the first end 31 of the support member 30 and the first winding start end 213 are not aligned. This eliminates the need for precise positioning of the support member 30 in the winding direction X, reducing manufacturing complexity and simplifying its installation. Furthermore, in the opposite direction of the winding direction X, the first segment 211 extends beyond the support member 30 and approaches the first end 31 of the first winding start end 213. The support member 30 does not completely cover the surface of the first segment 211 facing the winding axis P, reducing the amount of support member 30 used and helping to alleviate the problem of increased weight of the battery cell 100 due to the support member 30.

[0120] As shown in Figures 3-5, in some embodiments, in the opposite direction to the winding direction X, the first segment 211 includes a first portion 2113 extending beyond the first end 31, the length of the first portion 2113 being L, 0.5mm≤L≤15mm.

[0121] For example, L can be 0.5mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, etc.

[0122] By ensuring L ≥ 0.5mm, the portion of the first segment 211 extending beyond the first end 31 in the opposite direction of the winding direction X is sufficiently large, facilitating the placement of the support member 30. By ensuring L ≤ 15mm, the problem of reduced energy density in the cell 100 caused by the first segment 211 extending beyond the first end 31 in the opposite direction of the winding direction X is mitigated. Therefore, 0.5mm ≤ L ≤ 15mm not only facilitates the placement of the support member 30 but also alleviates the problem of reduced energy density in the cell 100 caused by the first segment 211 extending beyond the first end 31 in the opposite direction of the winding direction X.

[0123] The support member 30 can be made of various materials, such as plastic, ceramic, or metal. In some embodiments, the support member 30 is a metal part, such as an aluminum sheet, copper sheet, or steel sheet.

[0124] The support component 30 is made of metal, which has better strength and rigidity, making the inner ring layer A1 of the first electrode 21 more resistant to deformation. This further reduces the risk of the center of the wound electrode assembly 20 collapsing and deforming, thereby further effectively reducing lithium plating and improving the safety performance and service life of the cell 100.

[0125] In some embodiments, the support member 30 is made of stainless steel. Stainless steel has advantages such as high corrosion resistance, heat resistance, and durability. The use of stainless steel as the material of the support member 30 makes the support member 30 have good corrosion resistance, heat resistance, and durability. The support member 30 can better adapt to the internal environment of 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.

[0126] The support member 30 is made of different materials, and therefore has different bending strengths and moduli of elasticity. In some embodiments, the bending strength of the support member 30 is H, where 30MPa≤H≤300MPa.

[0127] Bending strength refers to the ability of a support member 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.

[0128] With H ≥ 30 MPa, the support member 30 has a high resistance to deformation, thus providing better support and reinforcement for the first end 31. This enhances the resistance to deformation of the first section 211, giving the inner ring A1 of the first electrode 21 a strong resistance to deformation. This reduces the risk of central collapse and deformation of the wound electrode assembly 20, effectively reducing lithium plating and improving the safety and lifespan of the cell 100. With H ≤ 300 MPa, given sufficient resistance to deformation of the support member 30, it avoids selecting a support member 30 with excessively high bending strength, which would increase costs and lead to over-performance of the support member 30. Therefore, 30 MPa ≤ H ≤ 300 MPa ensures that the inner ring A1 of the first electrode 21 has a strong resistance to deformation, reducing the risk of central collapse and deformation of the wound electrode assembly 20, thus effectively reducing lithium plating and improving the safety and lifespan of the cell 100, while also controlling the cost of the support member 30 and preventing over-performance of the support member 30.

[0129] Furthermore, in some embodiments of the first aspect of this application, 200 MPa ≤ H ≤ 300 MPa.

[0130] In one or more of the above optional embodiments, 200 MPa ≤ H ≤ 300 MPa can further enhance the strength of the inner ring A1 and further reduce the risk of collapse and deformation of the center of the electrode assembly 20.

[0131] In some embodiments, the elastic modulus of the support 30 is G, where 1.5 GPa ≤ G ≤ 200 GPa.

[0132] The elastic modulus is a measure of a support's ability to resist elastic deformation. For example, G can be 1.5GPa, 5GPa, 10GPa, 20GPa, 40GPa, 60GPa, 80GPa, 100GPa, 120GPa, 140GPa, 160GPa, 180GPa, 200GPa, etc.

[0133] With G ≥ 1.5 GPa, the support member 30 has good elastic deformation capability, causing the inner ring layer A1 of the first electrode 21 to rebound with an increased diameter. This supports the inner ring layer A1, reducing the risk of inward collapse of the inner ring layer A1 of the first electrode 21, thereby effectively reducing lithium plating and improving the safety performance and service life of the cell 100. With G ≤ 200 GPa, when the elastic deformation capability of the component support member 30 is sufficient, it avoids selecting a support member 30 with an excessively high elastic modulus, which would lead to increased cost and over-performance of the support member 30. Therefore, 1.5 GPa ≤ G ≤ 200 GPa can both reduce the risk of inward collapse of the inner ring layer A1 of the first electrode 21, thereby effectively reducing lithium plating and improving the safety performance and service life of the cell 100, and control the cost of the support member 30 and prevent over-performance of the support member 30.

[0134] Furthermore, in some embodiments of the first aspect of this application, 100GPa≤G≤200GPa.

[0135] In one or more of the above optional embodiments, by limiting 100GPa≤G≤200GPa, the elastic deformation capacity of the support 30 is further improved, reducing the risk of the inner ring layer A1 of the first electrode collapsing inward.

[0136] When the first electrode 21 is wound, the support member 30 can also be wound synchronously with the first electrode 21. The number of turns of the support member 30 can be less than one turn or at least one turn. Specifically, every 360° of winding along the winding direction X from the first end 31 constitutes one turn of the support member 30.

[0137] In some embodiments, the support 30 is wound at least one turn along the winding direction X.

[0138] When the number of turns of the support member 30 is an integer, the first end 31 and the second end 32 can be coplanar. For example, the support member 30 can be wound one, two, or three times around the winding axis P along the winding direction X. 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 shows the case where the support member 30 is wound one turn.

[0139] 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 surface P2 and the third reference surface P3 are different planes, and there is a distance between the second reference surface P2 and the third reference surface P3 along the winding direction X. For example, the support member 30 is wound around the winding axis P in the winding direction X for 0.5 turns, 1.5 turns, 2.5 turns, 3.5 turns, etc. Figure 7 shows the case where the number of turns of the support member 30 is non-integer.

[0140] By winding the support member 30 at least once along the winding direction X, the inner layer A1 of the first electrode 21 has stronger resistance to deformation, 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 cell 100.

[0141] As shown in Figures 2 and 3, in some embodiments, when viewed along the winding axis P of the vertical electrode assembly 20 and passing through the first end 31, the first end 31 and the second end 32 are coplanar.

[0142] Understandably, the support member 30 has an integer number of turns. The second reference plane P2 and the third reference plane P3 are on the same plane.

[0143] By observing along the winding axis P of the vertical electrode assembly 20 and passing through the first end 31, the first end 31 and the second end 32 are coplanar. Therefore, the number of turns of the support member 30 around the winding axis P is a whole turn, which facilitates the control of the length of the support member 30 along the winding direction X and the control of the number of turns of the support member 30.

[0144] In some embodiments, the support member 30 is wound at least two turns along the winding direction X. By winding the support member 30 at least two turns along the winding direction X, the deformation resistance of the inner layer A1 of the first electrode 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 cell 100. Figure 8 shows the case where the support member 30 is wound two turns.

[0145] As shown in Figure 3, in some embodiments, the support 30 does not extend beyond the first position Q along the winding direction X.

[0146] The second end 32 of the support member 30 may be flush with or at 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. Therefore, the support member 30 does not extend between the second segment 212 and the second pole piece 22 along the winding direction X.

[0147] Therefore, along the winding direction X, the support member 30 does not exceed the first position Q, reducing the risk that the support member 30 will puncture the separator 23 after extending between the first electrode 21 and the second electrode 22, causing a short circuit in the cell 100. It can also alleviate the problem that the electrode assembly 20 has a large structural size due to the support member 30, and alleviate the size difference between different parts of the electrode assembly 20, thereby reducing the risk of uneven stress on the electrode due to the expansion of the electrode assembly 20 during the cycle of the cell 100.

[0148] Specifically, as shown in Figure 3, 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 apart from the first position Q.

[0149] Along the winding direction X, the second end 32 is spaced apart from the first position Q to allow for a margin of safety so that the expansion of the electrode assembly 20 during the cell 100 cycle can cause misalignment between the first electrode 21 and the second electrode 22. This reduces the risk that the support member 30 will extend between the first electrode 21 and the second electrode 22 after the electrode assembly 20 expands, thereby reducing the risk that the support member 30 will puncture the separator 23 after extending between the first electrode 21 and the second electrode 22, resulting in a short circuit in the cell 100, and further improving the safety performance of the cell 100.

[0150] As shown in Figure 3, along the winding direction X, the distance between the second end 32 and the first position Q is K, where 0.5mm≤K≤15mm.

[0151] For example, K can be 0.5mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, etc.

[0152] By ensuring K ≥ 0.5 mm, sufficient distance is maintained between the second end 32 and the first position Q in the winding direction X. This provides ample leeway for misalignment between the first electrode 21 and the second electrode 22 caused by the expansion of the electrode assembly 20 during cell 100 cycling. This reduces the risk of the support member 30 extending between the first electrode 21 and the second electrode 22 after the electrode assembly 20 expands, thereby reducing the risk of the support member 30 puncturing the separator 23 and causing a short circuit in the cell 100, further improving the safety performance of the cell 100. By ensuring K ≤ 15 mm, the distance between the second end 32 and the first position Q in the winding direction X is avoided from being too large, which would result in insufficient support strength of the support member 30 for the first segment 211, failing to effectively mitigate the collapse of the center hole of the wound electrode assembly 20. Therefore, 0.5mm≤K≤15mm can reduce the risk of the support member 30 piercing the isolation membrane 23 after the electrode assembly 20 expands and extends between the first electrode 21 and the second electrode 22, thus causing a short circuit in the cell 100 and further improving the safety performance of the cell 100. It can also effectively improve the problem of the collapse of the center hole of the wound electrode assembly 20.

[0153] As shown in Figures 2 and 3, in some embodiments, when viewed along the winding axis P of the vertical 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.

[0154] That is, the second reference plane P2 and the first reference plane P1 are different planes.

[0155] The fact that the first end 31 and the second winding start end 221 are not coplanar helps to alleviate the problem of the large structural size of the electrode assembly 20 caused by the setting of the support member 30 in the battery cell 100, and to alleviate the size difference of each part of the electrode assembly 20, thereby reducing the risk of uneven stress on the electrode sheet caused by the expansion of the electrode assembly 20 during the cycling process of the battery cell 100.

[0156] As shown in Figures 2 and 3, in some embodiments, when viewed along the winding axis P of the vertical 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.

[0157] That is, the third reference plane P3 and the first reference plane P1 are different planes.

[0158] The second end 32 and the second winding start end 221 are not coplanar, which helps to alleviate the problem of the large structural size of the electrode assembly 20 caused by the setting of the support member 30 in the cell 100, and to alleviate the size difference of each part of the electrode assembly 20, thereby reducing the risk of uneven stress on the electrode sheet caused by the expansion of the electrode assembly 20 during the cycling process of the cell 100.

[0159] As shown in Figures 4 and 5, in some embodiments, the length of the support member 30 along the winding direction X is W, where 3mm ≤ W ≤ 32mm.

[0160] When the first electrode 21 is in the unfolded state, the length direction of the first electrode 21 and the length direction of the support member 30 correspond to the winding direction X when the first electrode 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 electrode 21.

[0161] For example, W can be 3mm, 5mm, 7mm, 9mm, 10mm, 11mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 24mm, 26mm, 28mm, 30mm, 32mm, etc.

[0162] The battery cell 100 also includes a second tab 222, which is electrically connected to the second electrode plate 22. When the first tab 214 is electrically connected to the housing 10, the second tab 222 can be electrically connected to the electrode terminal 13. When the first tab 214 is electrically connected to the electrode terminal 13, the second tab 222 can be electrically connected to the housing 10.

[0163] By way of example, referring to Figures 1, 2, 9 and 10, along the extension direction of the winding axis P, the housing 11 has a bottom wall 112 opposite to the cover 12.

[0164] 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.

[0165] Along the extension direction of the winding axis P, the support member 30 extends beyond the end of the first electrode 21 near the bottom wall 112 and the end of the second electrode 22 near the bottom wall 112, and the end of the support member 30 near the bottom wall 112 abuts against the surface of the second electrode tab 222 facing the electrode assembly 20.

[0166] In a traditional button cell, one of the tabs needs to be connected to the bottom wall 112 of the casing 11. This is achieved by passing a columnar support post through the middle of the cell 100, pressing against the surface of the tab electrically connected to the bottom wall 112 facing the electrode assembly 20 in the extension direction of the winding axis P. This allows the tab and the bottom wall 112 of the casing 11 to be welded from the outside. When the second tab 222 is welded to the bottom wall 112, the support member 30 is positioned beyond the end of the first electrode 21 near the bottom wall 112. The end of the electrode 22 near the bottom wall 112 and the end of the support 30 near the bottom wall 112 abut against the surface of the second tab 222 facing the electrode assembly 20, which can directly support the second tab 222 so that the bottom wall 112 and the second tab 222 remain in contact in the extension direction of the winding axis P. This facilitates welding of the second tab 222 and the bottom wall 112 and avoids the need to add support columns or other structures during the manufacturing process to keep the bottom wall 112 and the second tab 222 in contact, which would result in a larger inner hole in the cell 100.

[0167] In addition, when the elastic modulus is 200 MPa≤H≤300 MPa, or the bending strength is 30MPa≤H≤300MPa, the support effect of the support member 30 can be improved.

[0168] In some embodiments, the diameter of the central hole M of the electrode assembly 20 is 0.6 mm to 2.3 mm.

[0169] The central hole M is a central through-hole formed by the volume of the winding needle during the winding process of forming the electrode assembly 20. In one embodiment, the wall surface of the central hole M can be the surface of the separator 23.

[0170] For example, the diameter of the center hole can be 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.1mm, 2.2mm, 2.3mm, etc.

[0171] By extending along the winding axis P, the support member 30 extends beyond the end of the first electrode 21 near the bottom wall 112 and the end of the second electrode 22 near the bottom wall 112. The end of the support member 30 near the bottom wall 112 abuts against the surface of the second electrode tab 222 facing the electrode assembly 20. This allows the center hole of the electrode assembly 20 to be made smaller, less than 2.3 mm. The larger than 0.6 mm is due to the winding needle of the inner ring.

[0172] By testing battery cells 100 with different elastic moduli and bending strengths in the support member 30, the degree of inner ring collapse of the corresponding battery cell 100 is obtained. For Table 1, all parameters and structures of the battery cells 100 in the embodiments in Table 1 are the same except for the parameters listed in Table 1.

[0173] The degree of collapse of the inner ring layer of the electrode assembly 20 near the winding axis of the battery cell 100 can be tested using the following method:

[0174] The lithium-ion cells in each embodiment (cell 100 with support member 30) were subjected to charge-discharge cycle tests in a 25°C constant temperature chamber. The charge-discharge voltage range was 2.5V to 4.2V. The cells were charged at a constant current of 2C to 4.2V, then charged at a constant voltage of 4.2V to 0.05C and allowed to stand for 5 minutes. Finally, they were discharged at a constant current of 6C to 2.5V. This charge-discharge cycle was repeated 600 times. After the cell 100 was fully charged, a CT scan was performed to measure the degree of collapse. The degree of collapse was defined as the distance between the most convex position of the innermost electrode sheet of the electrode assembly 20 towards the winding center and the layer closest to the winding axis that did not show any indentation, measured five times and averaged. The test structures shown in Table 1 were obtained.

[0175] Table 1

[0176]

[0177] As shown in Table 1, in Examples 1-8, as the elastic modulus G of the support member 30 gradually increases, the degree of inner ring collapse of the battery cell gradually decreases. Especially after the elastic modulus of the support member 30 reaches 1.5 GPa, the degree of inner ring collapse is significantly lower than when the elastic modulus of the support member 30 is 1 GPa. Therefore, G ≥ 1.5 GPa results in a smaller degree of inner ring collapse in the battery cell 100, leading to improved safety and a shorter lifespan for the battery cell. As shown in Examples 7 and 8, when the elastic modulus of the support member 30 exceeds 200 GPa, the improvement in the degree of inner ring collapse is not significant with further increases in the elastic modulus of the support member 30. Furthermore, using a support member 30 with a larger elastic modulus leads to increased costs. Therefore, G ≤ 200 GPa can control the cost of the battery cell 100. In summary, 1.5GPa≤G≤200GPa can 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 cell, and controlling the production cost of the cell.

[0178] In Examples 9-18, as the bending stiffness H of the support member 30 gradually increases, the degree of inner ring collapse of the battery cell gradually decreases. Especially after the bending strength of the support member 30 reaches 30 MPa, the degree of inner ring collapse is significantly reduced compared to when the bending strength of the support member 30 is 20 MPa. Therefore, H ≥ 30 MPa results in a smaller degree of inner ring collapse in the battery cell 100, leading to improved safety and a shorter lifespan for the battery cell. As shown in Examples 17 and 18, when the bending strength of the support member 30 exceeds 300 GPa, the improvement in the degree of inner ring collapse is not significant with further increases in bending strength. Furthermore, using a support member 30 with a higher bending strength leads to increased costs. Therefore, H ≤ 300 MPa can control the cost of the battery cell 100. In summary, a pressure of 30MPa≤H≤300MPa can 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 cell, and controlling the production cost of the cell.

[0179] By testing battery cells 100 with different elastic moduli and bending strengths in the support member 30, the degree of inner ring collapse and short-circuit failure rate of the corresponding battery cell 100 are obtained. The testing method can refer to the aforementioned method, and will not be repeated here. For Table 2, all parameters and structures of the battery cells 100 in the embodiments in Table 2 are the same except for the parameters listed in Table 2.

[0180] Table 2

[0181]

[0182] As shown in Table 2, as the distance between the second end 32 and the first position Q along the winding direction increases, the degree of inner ring collapse of the cell 100 gradually increases, and the short-circuit failure rate of the 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, because the distance between the second end 32 and the first position Q along the winding direction is too small, after the cell 100 is cycled, the support member 30 is prone to extend between the first electrode and the second electrode, which increases the risk of short circuit of the 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 segment 211 between the second end 32 and the first position Q is not supported by the support member 30, and its resistance to deformation is weak, which makes the risk of collapse of the first segment 211 between the second end 32 and the first position Q greater, thus increasing the risk of short circuit of the cell 100. Therefore, 0.5mm≤K≤15mm can reduce the risk of the support extending between the first and second electrodes after the electrode assembly expands, thus puncturing the separator and causing a short circuit in the battery cell, further improving the safety performance of the battery cell. It can also effectively improve the problem of the collapse of the center hole of the wound electrode assembly.

[0183] This application also provides an electrical device, which includes the battery cell 100 provided in any of the above embodiments. The battery cell 100 provides electrical energy for the operation of the electrical device.

[0184] The battery cell 100 provided in any of the above embodiments has high safety performance and long service life, and the electrical equipment powered by the battery cell 100 has better power reliability.

[0185] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art.

Claims

1. A battery cell, comprising: A wound electrode assembly includes a first electrode and a second electrode with opposite polarities. The first electrode and the second electrode are stacked and wound along a winding direction to form a wound structure. The first electrode has a first winding start end, and the second electrode has a second winding start end. The first electrode includes a first segment and a second segment continuously arranged along the winding direction. The first segment and the second segment are connected at a first position. In a direction perpendicular to the winding axis of the electrode assembly and passing through the second winding start end, the first position is aligned with and adjacent to the second winding start end, and is located on the side of the second winding start end away from the winding axis. The end of the first segment away from the first position is the first winding start end. A support member is connected to the surface of the first segment facing the winding axis; Wherein, along the winding direction, the support member has a first end near the first winding start end, and in the opposite direction of the winding direction, the first segment extends beyond the first end.

2. The battery cell according to claim 1, wherein, The first segment includes a first current collection layer and a first active material layer. Along the thickness direction of the first current collection layer, the first current collection 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, wherein, The support is bonded or welded to the second surface.

4. The battery cell according to any one of claims 1-3, wherein, The support component is made of metal.

5. The battery cell according to claim 4, wherein, The support component is made of stainless steel.

6. The battery cell according to any one of claims 1-5, wherein, Along the winding direction, the support does not extend beyond the first position.

7. The battery cell according to claim 6, wherein, 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, wherein, Along the winding direction, the distance between the second end and the first position is K, where 0.5mm ≤ K ≤ 15mm.

9. The battery cell according to any one of claims 1-8, wherein, The bending strength of the support is H, 30MPa≤H≤300MPa.

10. The battery cell according to claim 9, wherein, 200 MPa≤H≤300 MPa.

11. The battery cell according to any one of claims 1-10, wherein, The elastic modulus of the support is G, where 1.5GPa≤G≤200GPa.

12. The battery cell according to claim 11, wherein, 100 GPa≤G≤200 GPa.

13. The battery cell according to any one of claims 1-12, wherein, In the opposite direction to the winding direction, the first segment includes a first portion extending beyond the first end, the length of which is L, 0.5mm≤L≤15mm.

14. The battery cell according to any one of claims 1-13, wherein, 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.

15. The battery cell according to any one of claims 1-14, wherein, Along the winding direction, the support member has a second end, which is disposed opposite to the first end; Viewed along 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 any one of claims 1-15, wherein, The support member is wound at least one turn along the winding direction.

17. The battery cell according to claim 16, wherein, Along the winding direction, the support member has a second end, which is disposed 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 or 17, wherein, The support member is wound at least two turns along the winding direction.

19. The battery cell according to any one of claims 1-18, wherein, The first electrode is the negative electrode, and the second electrode is the positive electrode.

20. The battery cell according to any one of claims 1-19, wherein, The battery cell is a button cell.

21. The battery cell according to claim 20, wherein, The battery cell includes a housing, and the electrode assembly is housed within the housing; The outer casing includes a housing and a cover, the housing having an opening, the cover sealing the opening, and the housing having a bottom wall opposite the cover along the extension direction of the winding axis; The battery cell also includes a first tab and a second tab. The first tab is electrically connected to the first electrode plate, and the second tab is electrically connected to the second electrode plate. The second tab is welded to the bottom wall. Along the extension direction of the winding axis, the support extends beyond the end of the first electrode plate near the bottom wall and the end of the second electrode plate near the bottom wall. The end of the support near the bottom wall abuts against the surface of the second tab facing the electrode assembly.

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

23. An electrical device comprising a battery cell according to any one of claims 1-22.

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