Battery cell and electric device

Abstract

The application provides an electric core and an electric device. The electric core comprises an electrode assembly with a winding structure, and the electrode assembly comprises a first pole piece and a first separator. A surface of a first base material of the first pole piece is provided with a first active material layer and an insulating layer. The first base material comprises a first current collector and a first tab. In the width direction of the first pole piece, the first tab is connected to one end of the first current collector. The first active material layer covers at least a part of the first current collector. The insulating layer covers at least a part of the first tab. The first active material layer has a first edge located at a first winding end of the first pole piece. The insulating layer has a second edge close to the first winding end. The first separator is connected to the surface of the first active material layer away from the first base material and the surface of the insulating layer away from the first base material. The first separator covers the first edge and the second edge. The risk of short circuit failure caused by the first edge and the second edge piercing the isolation film is reduced, and the safety of the electric core is improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to a battery cell and an electrical device. Background Technology

[0002] 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

[0003] This application provides a battery cell and an electrical device to improve the safety performance of the battery cell.

[0004] In a first aspect, embodiments of this application provide a battery cell, comprising an electrode assembly with a wound structure. The electrode assembly includes a first electrode sheet, which includes a first substrate, a first active material layer, and an insulating layer. Along the thickness direction of the first electrode sheet, at least one surface of the first substrate is provided with the first active material layer and the insulating layer. The first substrate includes a first current collector and a first tab. Along the width direction of the first electrode sheet, the first tab is connected to one end of the first current collector. The first active material layer covers at least a portion of the first current collector, and the insulating layer covers at least a portion of the first tab. Along the winding direction of the first electrode sheet, the first electrode sheet has a first winding termination end. The first active material layer has a first edge located at the first winding termination end, and the insulating layer has a second edge near the first winding termination end. The electrode assembly further includes a first separator, which is connected to the surface of the first active material layer facing away from the first substrate and the surface of the insulating layer facing away from the first substrate, and the first separator covers the first edge and the second edge.

[0005] In one or more of the above optional embodiments, the first active material layer has a first edge located at the first winding end, and the insulating layer has a second edge near the first winding end. The first edge and the second edge are covered by a first separator. The first separator can separate the separator from the first edge and the separator from the second edge, thereby reducing the risk of the first edge and the second edge puncturing the separator and causing short circuit failure during drop and roller tests or after mechanical abuse such as drop and roller tests. This improves the safety of the battery cell during drop and roller tests and under its operating conditions, and increases the pass rate of drop and roller tests.

[0006] In some embodiments of the first aspect of this application, along the width direction of the first electrode, the first spacer extends beyond the end of the insulating layer away from the first active material layer.

[0007] In one or more of the above optional embodiments, by extending the first separator beyond the end of the insulating layer away from the first active material layer, not only is the process of setting the insulating layer easier to implement, but it can also reduce the problem of active material powdering of the second electrode with the opposite polarity to the first electrode due to the thickness difference formed by setting the first separator during the winding process, as well as the problem of short circuit caused by tearing at the edge of the second electrode and piercing the separator during the cycling process, thereby improving the safety performance of the battery cell.

[0008] In some embodiments of the first aspect of this application, the first electrode tab includes a first connecting portion covered by an insulating layer, a first empty foil portion not covered by an insulating layer, and a first flattened portion. Along the width direction of the first electrode sheet, the first connecting portion is connected to one end of the first current collector, the first empty foil portion is located between the first connecting portion and the first flattened portion, and connects the first connecting portion and the first flattened portion. The first separator is spaced apart from the first flattened portion.

[0009] In one or more of the above optional embodiments, by spaced apart from the first partition and the first flattening portion along the width direction of the first electrode, the risk of the first partition being damaged and thus failing to function during the process of forming the first flattening portion by flattening or patting is reduced.

[0010] In some embodiments of the first aspect of this application, the first tab includes a first connecting portion covered by an insulating layer, a first empty foil portion not covered by an insulating layer, and a first flattened portion. Along the width direction of the first electrode sheet, the first connecting portion is connected to one end of the first current collector, and the first empty foil portion is located between the first connecting portion and the first flattened portion, and connects the first connecting portion and the first flattened portion. Along the width direction of the first electrode sheet, the size of the portion of the first separator extending beyond the insulating layer away from the first active material layer is smaller than the size of the first empty foil portion.

[0011] In one or more of the above optional embodiments, by making the portion of the first separator extending beyond the insulating layer away from the first active material layer smaller than the size of the first empty foil portion along the width direction of the first electrode sheet, it is beneficial for the first separator and the first flattened portion to be spaced apart along the width direction of the first electrode sheet, thereby reducing the risk of the first flattened portion coming into contact with the first separator and reducing the risk of the first separator being damaged and failing to function during the process of forming the first flattened portion by flattening or patting.

[0012] In some embodiments of the first aspect of this application, the first separator is connected to the surface of the first active material layer away from the first current collector, the surface of the insulating layer away from the first tab, and the surface of the first empty foil portion in the thickness direction.

[0013] In one or more of the above optional embodiments, the first separator is connected to the surface of the first active material layer away from the first current collector, the surface of the insulating layer away from the first electrode tab, and the surface of the first empty foil portion in the thickness direction. This helps to improve the connection stability of the first separator and reduce the risk of the first separator detaching from the first electrode and the first separator wrinkling.

[0014] In some embodiments of the first aspect of this application, along the thickness direction of the first electrode, the surface of the first separator away from the first substrate includes a first region, a second region, and a third region connected in sequence. The first region is disposed corresponding to the first active material layer, the second region is disposed corresponding to the insulating layer, and the third region is disposed corresponding to the first empty foil portion. The distance between the first region and the first substrate is D1, the distance between the second region and the first substrate is D2, and the distance between the third region and the first substrate is D3, where |D1-D2|≤5μm and |D1-D3|≤5μm.

[0015] In one or more of the above optional embodiments, by ensuring that |D1-D2|≤5μm and |D1-D3|≤5μm, the differences in the distances between the first region and the first substrate, the second region and the first substrate, and the third region and the first substrate are small. This reduces the thickness difference in the width direction of the first electrode sheet formed by the first separator and the first electrode sheet, thereby alleviating the problem of powder shedding from the second electrode sheet that is wound and bonded to the first electrode sheet during the winding process. It also reduces the safety issues caused by the thickness difference of the second electrode sheet formed by the first electrode sheet and the first separator, which can lead to tearing and puncture of the separator, causing short circuits, overheating, fire, and explosion, thereby improving the safety of the battery cell.

[0016] In some embodiments of the first aspect of this application, along the width direction of the first electrode, the dimension of the portion of the first separator extending beyond the insulating layer away from the first active material layer is H1, where 1mm≤H1≤3mm.

[0017] In one or more of the above optional embodiments, H1 ≥ 1mm facilitates the setting of the first separator, reduces the manufacturing difficulty, and allows the first separator to extend significantly beyond the insulating layer to better cover the edge of the insulating layer. This enables the first separator to separate the edge of the insulating layer in the width direction of the first electrode sheet from the separator film, reducing the risk of short circuit caused by the edge of the insulating layer piercing the separator film in the width direction of the first electrode sheet, thus improving the safety performance of the battery cell. H1 ≤ 3mm reduces the space occupied by the first separator, increases the energy density of the battery cell, and reduces the risk of damage to the first separator during the flattening of the first electrode tab. This allows the first separator to effectively reduce the risk of the edge of the first active material layer and the edge of the insulating layer piercing the separator film, further improving the safety performance of the battery cell. Therefore, 1mm ≤ H1 ≤ 3mm gives the battery cell good safety performance and energy density.

[0018] In some embodiments of the first aspect of this application, the first separator extends beyond the first winding end along the winding direction of the first electrode sheet.

[0019] In one or more of the above optional embodiments, by extending the first separator beyond the first winding end, not only is the process of setting the insulation layer easier to implement, but the first separator also better covers the first edge and the second edge. Thus, the first separator can separate the separator from the first edge, as well as separate the separator from the second edge. This reduces the risk of the battery cell failing due to the first and second edges puncturing the separator during drop and roller tests or after mechanical abuse such as drop and roller tests. It also improves the safety of the battery cell during drop and roller tests and under its operating conditions, and increases the pass rate of drop and roller tests.

[0020] In some embodiments of the first aspect of this application, along the thickness direction of the first electrode sheet, a first active material layer and an insulating layer are provided on both sides of the first substrate; the electrode assembly includes two first separators, each first separator including a first separation portion and a second separation portion, the first separation portions of the two first separators being located on both sides of the first electrode sheet respectively, and the two second separation portions extending beyond the first winding end and connected.

[0021] In one or more of the above optional embodiments, when a first active material layer and an insulating layer are provided on both sides of the first substrate, the electrode assembly includes two first separators that can cover the two opposite edges of the first winding end in the thickness direction, that is, cover the first edges of the two first active material layers and the second edges of the two insulating layers. The first separators can separate each first edge and the separator film, as well as the second edge and the separator film, reducing the risk of the first edge and the second edge piercing the separator film. The second separating portions of the two first separators extend beyond the first winding end and are connected. The two first separators can completely separate the first winding end and the separator film, so that the two first separators can form a closed space at the first winding end. This allows the two first separators to more stably separate the edge of the first winding end and the separator film, thereby reducing the risk of the edge of the positive electrode end piercing the separator film during drop testing or when the cell is in a drop condition, improving the safety of the cell and the pass rate of drop testing, and also making the connection between the first separator and the first electrode plate more stable, reducing the risk of the first separator detaching from the first electrode plate.

[0022] In some embodiments of the first aspect of this application, the surface of the second partition facing the first winding end is connected to the first winding end.

[0023] In one or more of the above optional embodiments, the surface of the second separator facing the first winding end is connected to the first winding end, so that the first separator can better separate the edge of the first winding end and the separator film, and can also improve the stability of the connection between the first separator and the first electrode, thereby further improving the safety performance of the battery cell.

[0024] In some embodiments of the first aspect of this application, the size of the first separator is W, 3mm≤W≤6mm, along the winding direction of the first electrode.

[0025] In one or more of the above optional embodiments, by using W≥3mm, the size of the first separator is larger, which can better cover the first edge and the second edge, reduce the risk of the first separator warping after winding, and facilitate the connection between the first separator and the first electrode. W≤6mm reduces the space occupied by the first separator and increases the energy density of the cell.

[0026] In some embodiments of the first aspect of this application, along the winding direction of the first electrode sheet, the first electrode sheet has a first winding start end, the first separator has a first end close to the first winding start end, and the distance between the first end and the first winding end is W1, 2mm≤W1≤3mm.

[0027] In one or more of the above optional embodiments, by having W1≥2mm, the portion of the first separator connected to the first electrode is made larger, which facilitates the connection between the first separator and the first electrode, reduces the risk of the first separator warping after winding, and improves the stability of the connection of the first separator; by having W1≤3mm, the area of ​​the first active material layer covered by the first separator is reduced, as well as the space occupied by the first separator, which increases the energy density of the cell. Therefore, 2mm≤W1≤3mm is beneficial to improving the connection stability of the first separator and the energy density of the cell.

[0028] In some embodiments of the first aspect of this application, along the width direction of the first electrode, the first spacer extends beyond the end of the first active material layer away from the insulating layer.

[0029] In one or more of the above optional embodiments, by extending the first separator beyond the end of the first active material layer away from the insulating layer along the width direction of the first electrode, the first separator can completely cover the first edge and at least a portion of the edge of the first active material layer away from the insulating layer. This reduces the risk of short-circuit failure caused by the first edge and the edge of the first active material layer away from the insulating layer piercing the separator during drop and drum testing or after mechanical abuse such as drop and drum tests. It improves the safety of the battery cell during drop and drum tests and under its operating conditions, and increases the pass rate of drop and drum tests. It also reduces the problem of active material powdering of the second electrode with the opposite polarity to the first electrode due to the thickness difference caused by the first separator, and even the problem of short circuit caused by tearing and piercing the separator at the edge of the second electrode during cycling, thus improving the safety performance of the battery cell.

[0030] In some embodiments of the first aspect of this application, the electrode assembly further includes a second electrode sheet, the second electrode sheet having opposite polarities to the first electrode sheet; the second electrode sheet includes a second substrate and a second active material layer, the second substrate includes a second current collector and a second tab, along the thickness direction of the second electrode sheet, at least one side of the second current collector is provided with the second active material layer, along the width direction of the second electrode sheet, the second tab includes a connected second empty foil portion and a second flattened portion, the second empty foil portion is connected to the end of the second current collector away from the first tab, the second flattened portion is connected to the end of the second empty foil portion away from the second current collector, and a first separator is spaced apart from the second flattened portion.

[0031] In one or more of the above optional embodiments, by spaced apart from the second flattening portion along the width direction of the second electrode, the risk of the first separator being damaged and thus failing to function during the process of forming the second flattening portion by flattening or patting is reduced.

[0032] In some embodiments of the first aspect of this application, along the width direction of the first electrode, the dimension of the end of the first separator that extends beyond the first active material layer and is away from the insulating layer is smaller than the dimension of the second empty foil portion.

[0033] In one or more of the above optional embodiments, by making the portion of the first separator extending beyond the first active material layer and away from the insulating layer smaller than the size of the second flattened portion along the width direction of the second electrode, the risk of the second flattened portion contacting the first separator is reduced. This is beneficial for the first separator and the second flattened portion to be spaced apart along the width direction of the second electrode, and reduces the risk that the first separator may be damaged and thus fail to function during the process of forming the second flattened portion by flattening or patting.

[0034] In some embodiments of the first aspect of this application, along the width direction of the first electrode, the dimension of the first separator extending beyond the end of the first active material layer away from the insulating layer is H2, where H2 ≥ 1 mm.

[0035] In one or more of the above optional embodiments, H2≥1mm facilitates the setting of the first separator, reduces the process difficulty, and makes the size of the first separator larger at the end of the first active material layer away from the insulating layer so as to better cover the edge of the first active material layer away from the insulating layer. This allows the first separator to separate the edge of the first active material layer in the width direction of the first electrode from the separator, reducing the risk of the edge of the first active material layer in the width direction of the first electrode piercing the separator and causing a short circuit, and improving the safety performance of the battery cell.

[0036] In some embodiments of the first aspect of this application, along the winding direction of the first electrode sheet, the size of the first current collector is L1, the size of the first electrode tab is L2, and 0.5≤L2 / L1≤1.

[0037] In one or more of the above optional implementation methods, by using 0.5≤L2 / L1≤1, the size of the first tab in the winding direction of the first electrode is relatively large, which is beneficial to improving the output power of the battery cell and reducing the internal resistance and charging / discharging temperature rise of the battery cell.

[0038] In some embodiments of the first aspect of this application, the first separator includes adhesive tape.

[0039] In one or more of the above optional embodiments, the adhesive tape has good flexibility. The first separator includes adhesive tape, which facilitates winding after the first separator is connected to the first electrode, and can reduce the risk of the first separator curling up after winding. Moreover, the adhesive tape form of the first separator facilitates the connection between the first separator and the first electrode.

[0040] In some embodiments of the first aspect of this application, the first electrode has a first winding start end, the first active material layer has a third edge located at the first winding start end, and the insulating layer has a fourth edge near the first winding start end. The electrode assembly further includes a second spacer connected to the surface of the first active material layer opposite to the first substrate and the surface of the insulating layer opposite to the first substrate, and the second spacer covers the third edge and the fourth edge.

[0041] In one or more of the above optional embodiments, the second active material layer has a third edge located at the first winding start end, and the insulating layer has a fourth edge near the first winding start end. The third edge and the fourth edge are covered by a second separator. The second separator can separate the separator from the third edge and the fourth edge, thereby reducing the risk of the third edge and the fourth edge puncturing the separator and causing short circuit failure during drop and drum tests or after mechanical abuse such as drop and drum tests. This improves the safety of the battery cell during drop and drum tests and under its operating conditions, and increases the pass rate of drop and drum tests.

[0042] In some embodiments of the first aspect of this application, the first electrode is a positive electrode.

[0043] In one or more of the above optional embodiments, the first electrode is a positive electrode, and the first separator can separate the edge corresponding to the positive electrode end and the negative electrode closest to the positive electrode end. After the electrode assembly expands to abut against the outer shell, the first separator can effectively relieve or release the stress of the negative electrode closest to the positive electrode end at the position corresponding to the positive electrode end, thereby making the negative current collector of the negative electrode less prone to breakage.

[0044] In some embodiments of the first aspect of this application, the electrode assembly further includes a second electrode, which is a negative electrode. The second electrode extends beyond the first winding end along the winding direction of the first electrode, and a first separator is provided on either side of the first winding end facing the second electrode.

[0045] In one or more of the above optional embodiments, a first separator is provided on either side of the first winding end facing the second electrode. The first separator can separate the edge corresponding to the positive electrode end and the negative electrode closest to the positive electrode end. After the electrode assembly expands to abut against the outer shell, the first separator can effectively relieve or release the stress of the negative electrode closest to the positive electrode end at the position of the corresponding positive electrode end, thereby making the negative current collector of the negative electrode less likely to break.

[0046] Secondly, embodiments of this application provide an electrical device, which includes the battery cell provided in any embodiment of the first aspect.

[0047] In the above technical solutions, the battery cell provided in any embodiment of the first aspect has good safety performance and can improve the power safety and reliability of electrical equipment powered by the battery cell. Attached Figure Description

[0048] 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.

[0049] Figure 1 Exploded views of battery cells provided in some embodiments of this application;

[0050] Figure 2 This is a schematic diagram of the structure of the electrode assembly and the first separator provided in some embodiments of this application;

[0051] Figure 3 A schematic diagram showing the first electrode in an unfolded state, provided for some embodiments of this application;

[0052] Figure 4 for Figure 3 A sectional view along the P1-P1 direction;

[0053] Figure 5 A schematic diagram showing the first electrode in an unfolded state, provided for other embodiments of this application;

[0054] Figure 6 for Figure 5 A sectional view along the P2-P2 direction;

[0055] Figure 7 for Figure 2 Enlarged view at point A1;

[0056] Figure 8 This is a schematic diagram of the structure of an electrode assembly provided in some embodiments of this application;

[0057] Figure 9 for Figure 3 A sectional view along line P3-P3;

[0058] Figure 10 for Figure 3 A sectional view along line P4-P4;

[0059] Figure 11 Schematic diagrams of the electrode assembly, the first separator, and the second separator provided in other embodiments of this application;

[0060] Figure 12 for Figure 11 Enlarged view at point A2;

[0061] Figure 13 A schematic diagram showing the first electrode in an unfolded state, provided for some embodiments of this application;

[0062] Figure 14 for Figure 13 A sectional view along the P5-P5 direction;

[0063] Figure 15 for Figure 13 A sectional view along line P6-P6 in the middle;

[0064] Figure 16 for Figure 13 Sectional view along line P7-P7.

[0065] Icons: 100-cell; 10-casing; 11-shell; 12-cover; 20-electrode assembly; 21-first electrode; 21a-first winding start end; 21b-first winding end; 211-first substrate; 2111-first current collector; 2112-first tab; 21121-first connecting part; 21122-first empty foil part; 21123-first flattened part; 212-first active material layer; 2121-first edge; 2122-third edge; 213-insulating layer; 2131-second edge; 2132-fourth edge; 22-second electrode; 22a-second The end of the electrode sheet; 221-Second substrate; 22111-Second current collector; 22112-Second electrode tab; 221122-Second empty foil portion; 221123-Second flattened portion; 222-Second active material layer; 23-Separating membrane; 24-First separator; 24a-First end; 241-First separator portion; 242-Second separator portion; 243-First region; 244-Second region; 245-Third region; 25-Second separator; X-Wrapping direction of the first electrode sheet; X'-Length direction of the first electrode sheet; Y-Width direction of the first electrode sheet; Z-Thickness direction of the first electrode sheet; Q-Overlapping region. Detailed Implementation

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] The electrode assembly of the battery cell includes two electrodes with opposite polarities. Along the winding direction of the electrode assembly, the winding end of the electrode is the cutting position during the electrode production process. After the electrode assembly is wound, the position of the electrode assembly at the winding end of the electrode is relatively close to the inner wall of the shell compared to other positions. After the electrode assembly expands, the position of the electrode assembly at the winding end of the electrode is the first to come into contact with the inner wall of the shell. The shell exerts a force on the position of the electrode assembly at the winding end, making the edge formed at the winding end easy to puncture the separator, causing the battery cell to short-circuit and fail. This reduces the safety performance of the battery cell in drop and tumbling tests and during use, and also reduces the pass rate of drop and tumbling tests.

[0072] Based on the above considerations, in order to alleviate the problem of reduced cell safety performance caused by the edge of the winding end of the electrode piercing the separator, this application provides a cell. The cell includes an electrode assembly with a winding structure. The electrode assembly includes a first electrode, which includes a first substrate, a first active material layer, and an insulating layer. Along the thickness direction of the first electrode, at least one side surface of the first substrate is provided with the first active material layer and the insulating layer. The first substrate includes a first current collector and a first tab. Along the width direction of the first electrode, the first tab is connected to one end of the first current collector. The first active material layer covers at least a portion of the first current collector, and the insulating layer covers at least a portion of the first tab. Along the winding direction of the first electrode, the first electrode has a first winding end. The first active material layer has a first edge located at the first winding end, and the insulating layer has a second edge close to the first winding end. The electrode assembly also includes a first separator, which is connected to the surface of the first active material layer away from the first substrate and the surface of the insulating layer away from the first substrate, and the first separator covers the first edge and the second edge.

[0073] The first active material layer has a first edge located at the first winding end, and the insulating layer has a second edge near the first winding end. The first edge and the second edge are covered by a first separator. The first separator can separate the separator from the first edge and the separator from the second edge, thereby reducing the risk of short circuit failure caused by the first edge and the second edge puncturing the separator during drop and roller tests or after mechanical abuse such as drop and roller tests. This improves the safety of the battery cell during drop and roller tests and under its operating conditions, and increases the pass rate of drop and roller tests.

[0074] 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. Battery cells conforming to the operating conditions of this application can also be used as the power supply system for electrical equipment.

[0075] 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.

[0076] like Figure 1 , Figure 2 As shown, this application provides a battery cell 100, which includes a housing 10 and an electrode assembly 20, with the electrode assembly 20 housed within the housing 10.

[0077] 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.

[0078] The housing 10 may include a housing 11 and a cover 12, the housing 11 having an opening at at least one end, and the cover 12 for sealing the opening of the housing 11 so that the housing 11 and the cover 12 together define an accommodating space.

[0079] like Figure 2 As shown, the electrode assembly 20 includes a first electrode 21, a second electrode 22, and a separator 23. The first electrode 21 and the second electrode 22 have opposite polarities, that is, one of the first electrode 21 and the second electrode 22 is a positive electrode and the other is a negative electrode.

[0080] The positive electrode includes a positive current collector and a positive active material layer, with the positive active material layer disposed on at least one side of the positive current collector. For the lithium-ion cell 100, the positive current collector can be made of 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.

[0081] The negative electrode includes a negative current collector and a negative active material layer, with the negative active material layer disposed on at least one side of the negative current collector. For the lithium-ion cell 100, the material of the negative current collector can be copper, and the negative active material can be carbon or silicon, etc. The negative current collector can be a composite current collector or a non-composite current collector.

[0082] The separator 23 provides insulation between the first electrode 21 and the second electrode 22, reducing the risk of short circuit in the cell 100. The material of the separator 23 may include PP (polypropylene) or PE (polyethylene), etc.

[0083] The electrode assembly 20 has a wound structure. A first electrode 21, a separator 23, a second electrode 22, and another separator 23 are stacked in a specific order and then wound to form the electrode assembly 20 with the wound structure; alternatively, the separator 23, the first electrode 21, the other separator 23, and the second electrode 22 are stacked in a specific order and then wound to form the electrode assembly with the wound structure. The electrode assembly 20 with the wound structure can be a flat wound electrode assembly, a cylindrical electrode assembly 20, or a columnar electrode assembly. In embodiments where the electrode assembly 20 has a cylindrical structure, the battery cell 100 can be a cylindrical battery cell. Figure 1 The image shows the case where cell 100 is a cylindrical cell. Figure 2 The diagram shows the case where the electrode assembly 20 has a cylindrical structure.

[0084] The first electrode 21 includes a first substrate 211, a first active material layer 212, and an insulating layer 213. Along the thickness direction Z of the first electrode, the first active material layer 212 and the insulating layer 213 are disposed on at least one side surface of the first substrate 211. The first substrate 211 includes a first current collector 2111 and a first tab 2112. Along the width direction Y of the first electrode, the first tab 2112 is connected to one end of the first current collector 2111. The first active material layer 212 covers at least a portion of the first current collector 2111, and the insulating layer 213 covers at least a portion of the first tab 2112. Along the winding direction X of the first electrode, the first electrode 21 has a first winding start end 21a and a first winding end end 21b.

[0085] The first winding start end 21a is the starting end of the winding of the first electrode 21, and the first winding end end 21b is the ending end of the winding of the first electrode 21.

[0086] The first current collector 2111 and the first tab 2112 can be integrally formed, for example, by die-cutting a substrate to form the first current collector 2111 and the first tab 2112, thereby making the first current collector 2111 and the first tab 2112 integrally formed. Alternatively, the first current collector 2111 and the first tab 2112 can be separately arranged and connected as one unit, for example, the first tab 2112 can be welded to the first current collector 2111.

[0087] The number of first tabs 2112 can be one or more. In embodiments where there are multiple first tabs 2112, the multiple first tabs 2112 are spaced apart along the winding direction X of the first electrode sheet. Figure 3 The diagram shows the case where there is only one first electrode tab 2112.

[0088] Along the winding direction X of the first electrode sheet, the size of the first electrode tab 2112 and the size of the first current collector 2111 can be the same or different.

[0089] For example, such as Figure 3 , Figure 5 As shown, along the winding direction X of the first electrode, the size of the first current collector 2111 is L1, the size of the first tab 2112 is L2, and 0.5≤L2 / L1≤1.

[0090] When L2 / L1=1, along the winding direction X of the first electrode, the size of the first current collector 2111 and the size of the first tab 2112 are the same, and the two ends of the first tab 2112 can be flush with the two ends of the first current collector 2111. Figure 3 and Figure 5The diagram shows that when the first electrode 21 is in the unfolded state, along the length direction X' of the first electrode, the two ends of the first electrode tab 2112 are flush with the two ends of the first current collector 2111.

[0091] When L2 / L1 < 1, along the winding direction X of the first electrode sheet, the size of the first electrode tab 2112 is smaller than the size of the first current collector 2111.

[0092] For example, L2 / L1 can be 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, etc.

[0093] By using 0.5≤L2 / L1≤1, the size of the first tab 2112 in the winding direction X of the first electrode is larger, which is beneficial to improving the output power of the cell 100 and reducing internal resistance and temperature rise.

[0094] It should be noted that the winding direction X of the first electrode corresponds to the length direction X' of the first electrode when it is in the unfolded state.

[0095] like Figure 3 , Figure 4 As shown, along the width direction Y of the first electrode, the insulating layer 213 can be completely disposed on one side of the first active material layer 212, and the end face of the insulating layer 213 near the first active material layer 212 is in contact or connected to the end face of the first active material layer 212 near the insulating layer 213.

[0096] like Figure 5 , Figure 6 As shown, in some embodiments, in the width direction Y of the first electrode, the insulating layer 213 may be partially located on one side of the first active material layer 212. Viewed along the thickness direction Z of the first electrode, a portion of the first active material layer 212 and the insulating layer 213 overlap, forming an overlap region Q. In the width direction Y of the first electrode, another portion of the insulating layer 213 and another portion of the first active material layer 212 are located on opposite sides of the overlap region Q. In the overlap region Q, the insulating layer 213 is located on the side of the first active material layer 212 facing away from the first substrate 211.

[0097] The width direction Y of the first electrode corresponds to the winding axis direction of the electrode assembly 20. When the first electrode 21 is in the unfolded state, the length direction X', the width direction Y, and the thickness direction Z of the first electrode are perpendicular to each other.

[0098] The insulating layer 213 can be a ceramic layer, an adhesive layer, adhesive paper, etc.

[0099] Along the thickness direction Z of the first electrode sheet, a first active material layer 212 and an insulating layer 213 may be provided on one side of a portion of the first substrate 211, and the first active material layer and insulating layer 213 may be provided on both sides of another portion of the first substrate 211. For example, in an embodiment where the first winding end 21b is located at the outermost electrode sheet of the electrode assembly 20, the first substrate 211 of the outermost ring of the first electrode sheet 21 may only have the first active material layer 212 and insulating layer 213 provided on the surface facing the winding center, while the other rings of the first substrate 211 of the first electrode sheet 21 have the first active material layer 212 and insulating layer 213 provided on both the surfaces facing the winding center and the surfaces away from the winding center.

[0100] like Figures 2-7 As shown, along the thickness direction Z of the first electrode, the surfaces on both sides of the first substrate 211 can be provided with a first active material layer 212 and an insulating layer 213. Figures 2-7 The diagram shows that the first electrode 21 is the positive electrode and the second electrode 22 is the negative electrode. The outermost electrode of the electrode assembly 20 is the negative electrode, meaning the outermost ring of the second electrode 22 is the outermost electrode of the electrode assembly 20. The tail end 22a of the second electrode is located outside the first winding tail end 21b, and the first winding tail end 21b is located inside the outermost ring of the second electrode 22. Along the winding direction X of the first electrode, the outermost ring of the second electrode 22 extends beyond the first winding tail end 21b. Along the winding direction X of the first electrode, there is a corresponding first electrode 21 on both sides of any position of the first electrode 21. Therefore, along the thickness direction Z of the first electrode, a first active material layer 212 and an insulating layer 213 are provided on both sides of the first substrate 211.

[0101] In the winding direction X of the first electrode, one end of the first active material layer 212 is located at the first winding termination end 21b. Understandably, one end of the first active material layer 212 is a part of the first winding termination end 21b. The first edge 2121 of the first active material layer 212 forms at least a portion of an edge of the first winding termination end 21b in the thickness direction Z of the first electrode.

[0102] The second edge 2131 is an edge of the insulating layer 213 near the first winding termination end 21b. In an embodiment where the two ends of the first tab 2112 are flush with the two ends of the first current collector 2111 along the length direction X' of the first electrode sheet, the second edge 2131 can be located at the first winding termination end 21b. Understandably, one end of the insulating layer 213 is part of the first winding termination end 21b, and the second edge 2131 of the insulating layer 213 forms part of an edge of the first winding termination end 21b along the thickness direction Z of the first electrode sheet. Of course, the second edge 2131 can be at a distance from the first winding termination end 21b along the winding direction X of the first electrode sheet.

[0103] like Figures 3-7 As shown, in some embodiments, the electrode assembly 20 further includes a first separator 24, which is connected to the surface of the first active material layer 212 facing away from the first substrate 211 and the surface of the insulating layer 213 facing away from the first substrate 211, and the first separator 24 covers the first edge 2121 and the second edge 2131.

[0104] The first separator 24 can be made of insulating material to reduce the risk of short circuit in the cell 100. The first separator 24 can also be made of a softer material to reduce the risk of the first separator 24 puncturing the separator membrane 23.

[0105] For example, the first separator 24 includes adhesive tape. The adhesive tape has good flexibility, and the inclusion of adhesive tape in the first separator 24 facilitates winding after it is connected to the first electrode 21, and reduces the risk of the first separator 24 warping at the edges after winding. Furthermore, the adhesive tape form of the first separator 24 facilitates the connection between the first separator 24 and the first electrode 21. The adhesive tape used as the first separator 24 can be made of materials such as PI (Polyimide), PET (Polyethylene terephthalate), PP (Polypropylene), or PVDF (polyvinylidene fluoride).

[0106] The first separator 24 may be adhered to the surface of the first active material layer 212 that is away from the first substrate 211.

[0107] Along the winding direction X of the first electrode sheet, one end of the first separator 24 may be flush with the first edge 2121 or the first separator 24 may extend beyond the first edge 2121, so that the first separator 24 covers the first edge 2121.

[0108] Along the winding direction X of the first electrode sheet, one end of the first separator 24 may be flush with the second edge 2131 or the first separator 24 may extend beyond the second edge 2131, so that the first separator 24 covers the second edge 2131.

[0109] By covering the first edge 2121 and the second edge 2131 with the first separator 24, the first separator 24 can separate the isolation membrane 23 and the first edge 2121, as well as separate the isolation membrane 23 and the second edge 2131. This reduces the risk of the first edge 2121 and the second edge 2131 puncturing the isolation membrane 23 and causing short circuit failure during drop and roller tests or after mechanical abuse such as drop and roller tests. This improves the safety of the battery cell 100 during drop and roller tests and under its operating conditions, and increases the pass rate of the battery cell 100 in drop and roller tests.

[0110] In the embodiment where the first electrode 21 is a positive electrode, the first separator 24 can separate the edge corresponding to the positive electrode termination and the negative electrode closest to the positive electrode termination. After the electrode assembly 20 expands to abut against the outer shell 10, the first separator 24 can effectively relieve or release the stress of the negative electrode closest to the positive electrode termination at the corresponding positive electrode termination position, thereby making the negative current collector of the negative electrode less prone to breakage.

[0111] In an embodiment where the first electrode 21 is a positive electrode and the second electrode 22 is a negative electrode, the second electrode 22 extends beyond the first winding end 21b along the winding direction X of the first electrode, and a first separator 24 is provided on any side of the first winding end 21b facing the second electrode 22.

[0112] A first separator 24 is provided on either side of the first winding end 21b facing the second electrode 22. The first separator 24 can separate the edge corresponding to the positive electrode end and the negative electrode closest to the positive electrode end. After the electrode assembly 20 expands to abut against the outer shell 10, the first separator 24 can effectively relieve or release the stress of the negative electrode closest to the positive electrode end at the corresponding positive electrode end position, thereby making the negative current collector of the negative electrode less likely to break.

[0113] like Figures 3-6 As shown, in some embodiments, along the width direction Y of the first electrode, the first separator 24 extends beyond the insulating layer 213 at one end away from the first active material layer 212.

[0114] The first separator 24 extends beyond the end of the insulating layer 213 away from the first active material layer 212. This facilitates the separation of the separator 24 from the edge of the insulating layer 213 away from the first active material layer 212, reducing the risk of the insulating layer 213 puncturing the separator 23 due to its distance from the edge of the first active material layer 212, and improving the safety performance of the cell 100. It should be noted that in embodiments where the insulating layer 213 and the first active material layer 212 overlap to form an overlap region Q, along the width direction Y of the first electrode, the end of the insulating layer 213 away from the first active material layer 212 can be the end of the insulating layer 213 away from the overlap region Q.

[0115] By extending the first separator 24 beyond the insulating layer 213 and away from the first active material layer 212, not only is the process of setting the insulating layer 213 easier to implement, but it also reduces the problem of active material powdering of the second electrode 22 with the opposite polarity to the first electrode 21 caused by the thickness difference formed by setting the first separator 24 during the winding process, as well as the problem of short circuit caused by tearing at the edge of the second electrode 22 and piercing the separator during the cycling process, thereby improving the safety performance of the cell 100.

[0116] The dimension of the first separator 24 extending beyond the insulating layer 213 and away from the first active material layer 212 along the width direction Y of the first electrode sheet is set according to actual needs. For example, as shown... Figures 3-6 As shown, along the width direction Y of the first electrode, the dimension of the portion of the first separator 24 extending beyond the insulating layer 213 and away from the first active material layer 212 is H1, where 1mm≤H1≤3mm.

[0117] H1 can be 1mm, 1.2mm, 1.4mm, 1.5mm, 1.7mm, 1.9mm, 2mm, 2.2mm, 2.5mm, 2.7mm, 3mm, etc.

[0118] By using H1 ≥ 1 mm, the first separator 24 is easier to set, reducing manufacturing difficulty. It also allows the first separator 24 to extend significantly beyond the insulating layer 213, better covering its edge. This enables the first separator 24 to separate the edge of the insulating layer 213 in the width direction Y of the first electrode from the separator 23, reducing the risk of the edge of the insulating layer 213 puncturing the separator 23 and causing a short circuit, thus improving the safety performance of the cell 100. H1 ≤ 3 mm reduces the space occupied by the first separator 24, increasing the energy density of the cell 100. It also reduces the risk of damage to the first separator 24 during the flattening process of the first electrode tab 2112, effectively reducing the risk of the edge of the first active material layer 212 and the edge of the insulating layer 213 puncturing the separator 23, further improving the safety performance of the cell 100. Therefore, 1 mm ≤ H1 ≤ 3 mm gives the cell 100 good safety performance and energy density.

[0119] like Figure 8 As shown, in some embodiments, the first electrode tab 2112 includes a first connecting portion 21121 covered by an insulating layer 213, a first empty foil portion 21122 not covered by the insulating layer 213, and a first flattened portion 21123. Along the width direction Y of the first electrode sheet, the first connecting portion 21121 is connected to one end of the first current collector 2111, the first empty foil portion 21122 is located between the first connecting portion 21121 and the first flattened portion 21123, and connects the first connecting portion 21121 and the first flattened portion 21123. The first separator 24 is spaced apart from the first flattened portion 21123.

[0120] The first flattened portion 21123 can be a structure formed by a flattening process or a patting process. Along the width direction Y of the first electrode sheet, the insulating layer 213 covers a portion of the surface along the first electrode tab 2112, and the area covered by the insulating layer 213 along the width direction Y of the first electrode sheet is the first connecting portion 21121.

[0121] Along the width direction Y of the first electrode, the first separator 24 can be spaced apart from any position of the first flattening portion 21123 facing the first connecting portion 21121, or the first separator 24 can be spaced apart from a portion of the first flattening portion 21123 facing the first connecting portion 21121.

[0122] By spacing the first separator 24 and the first flattening portion 21123 along the width direction Y of the first electrode, the risk of the first separator 24 being damaged and thus failing to function during the process of forming the first flattening portion 21123 by flattening or patting is reduced.

[0123] In some embodiments, along the width direction Y of the first electrode, the size of the portion of the first separator 24 extending beyond the insulating layer 213 away from the first active material layer 212 is smaller than the size of the first empty foil portion 21122.

[0124] By having the portion of the first separator 24 extending beyond the insulating layer 213 and away from the first active material layer 212 along the width direction Y of the first electrode sheet smaller than the size of the first empty foil portion 21122, it is advantageous for the first separator 24 and the first flattened portion 21123 to be spaced apart along the width direction Y of the first electrode sheet. This reduces the risk of the first flattened portion 21123 coming into contact with the first separator 24, and also reduces the risk that the first separator 24 may be damaged during the process of forming the first flattened portion 21123 by flattening or patting, thus causing the first separator 24 to fail.

[0125] like Figure 4 , Figure 6 As shown, in some embodiments, the first separator 24 is connected to the surface of the first active material layer 212 away from the first current collector 2111, the surface of the insulating layer 213 away from the first tab 2112, and the surface of the first empty foil portion 21122 in the thickness direction.

[0126] That is, the surface of the first active material layer 212 facing away from the first current collector 2111, the surface of the insulating layer 213 facing away from the first electrode tab 2112, and the surface of the first empty foil portion 21122 in the thickness direction are all connected to the first separator 24.

[0127] The surface of the first active material layer 212 facing away from the first current collector 2111, the surface of the insulating layer 213 facing away from the first electrode tab 2112, and the surface of the first empty foil portion 21122 in the thickness direction can all be bonded to the first separator 24.

[0128] The first separator 24 is connected to the surface of the first active material layer 212 away from the first current collector 2111, the surface of the insulating layer 213 away from the first electrode tab 2112, and the surface of the first empty foil portion 21122 in the thickness direction. This helps to improve the connection stability of the first separator 24 and reduce the risk of the first separator 24 detaching from the first electrode 21 and the first separator 24 wrinkling.

[0129] Please continue to refer to Figure 4 , Figure 6 In some embodiments, along the thickness direction Z of the first electrode, the surface of the first separator 24 facing away from the first substrate 211 includes a first region 243, a second region 244, and a third region 245 connected in sequence. The first region 243 is correspondingly disposed with the first active material layer 212, the second region 244 is correspondingly disposed with the insulating layer 213, and the third region 245 is correspondingly disposed with the first empty foil portion 21122. The distance between the first region 243 and the first substrate 211 is D1, the distance between the second region 244 and the first substrate 211 is D2, and the distance between the third region 245 and the first substrate 211 is D3, where |D1-D2|≤5μm and |D1-D3|≤5μm.

[0130] When the first electrode 21 is in the unfolded state, D1 is the distance between the surface of the first substrate 211 facing the first region 243 and the first region 243 in the thickness direction Z of the first electrode, D2 is the distance between the surface of the first substrate 211 facing the second region 244 and the second region 244 in the thickness direction Z of the first electrode, and D3 is the distance between the surface of the first substrate 211 facing the third region 245 and the third region 245 in the thickness direction Z of the first electrode.

[0131] In this embodiment, the third region 245 is a part of the surface of the first substrate 211 facing the first region 243, and D3 is the thickness of the first separator 24 corresponding to the third region 245.

[0132] The thicknesses of the first separator 24 corresponding to the first region 243, the first separator 24 corresponding to the second region 244, and the first separator 24 corresponding to the third region 245 can be different. For example, when the thicknesses of the insulating layer 213 and the first active material layer 212 are different, in order to make D1 and D2 the same, the thicknesses of the first separator 24 corresponding to the first region 243 and the first separator 24 corresponding to the second region 244 can be different. Figure 4The diagram shows the case where the thickness of the insulating layer 213 is less than the thickness of the first active material layer 212. In order to make D1, D2, and D3 the same, and with the first separator 24 connected to the surface of the first active material layer 212 away from the first current collector 2111, the surface of the insulating layer 213 away from the first tab 2112, and the surface of the first empty foil portion 21122 in the thickness direction, the thickness of the first separator 24 corresponding to the first region 243 is greater than the thickness of the first separator 24 corresponding to the second region 244, and the thickness of the first separator 24 corresponding to the third region 245 is greater than the thickness of the first separator 24 corresponding to the third region 245.

[0133] The distances D1 between the first region 243 and the first substrate 211, D2 between the second region 244 and the first substrate 211, and D3 between the third region 245 and the first substrate 211 can be the same or different. When D1, D2, and D3 are the same, the first region 243, the second region 244, and the third region 245 are flush, which can alleviate the problem of thickness difference between the first electrode 21 and the first separator 24 at corresponding positions of the first separator 24.

[0134] For example, |D1-D2| can be 0μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, etc. |D1-D3| can be 0μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, etc.

[0135] By ensuring that |D1-D2|≤5μm and |D1-D3|≤5μm, the differences in distances between the first region 243 and the first substrate 211, the second region 244 and the first substrate 211, and the third region 245 and the first substrate 211 are minimized. This reduces the thickness difference in the width direction Y of the first electrode sheet formed by the first separator 24 and the first electrode sheet 21, thereby alleviating the problem of powder shedding from the second electrode sheet 22 that is wound and bonded to the first electrode sheet 21 during the winding process. It also reduces the safety issues caused by the thickness difference of the second electrode sheet 22 formed by the first electrode sheet 21 and the first separator 24, which could lead to tearing, puncture of the separator, short circuit, overheating, fire, and explosion. This improves the safety of the battery cell 100.

[0136] like Figures 3-6 As shown, in some embodiments, along the width direction Y of the first electrode, the first separator 24 extends beyond the end of the first active material layer 212 away from the insulating layer 213.

[0137] Along the width direction Y of the first electrode, the end of the first active material layer 212 away from the insulating layer 213 is flush with the end of the first current collector 2111 away from the first tab 2112. Along the width direction Y of the first electrode, the first separator 24 extends beyond the end of the first active material layer 212 away from the insulating layer 213. This can be understood as the first separator 24 extending beyond the end of the first electrode 21 where the first tab 211 is not provided.

[0138] The first separator 24 extends beyond the end of the first active material layer 212 away from the insulating layer 213. This facilitates the separation of the separator 24 from the edge of the first active material layer 212 away from the insulating layer 213, reducing the risk of the edge of the first active material layer 212 puncturing the separator 23 and improving the safety performance of the cell 100. It should be noted that in embodiments where the insulating layer 213 and the first active material layer 212 overlap to form an overlap region Q, along the width direction Y of the first electrode, the end of the first active material layer 212 away from the insulating layer 213 can be the end of the first active material layer 212 away from the overlap region Q.

[0139] By extending the first separator 24 beyond the end of the first active material layer 212 away from the insulating layer 213 along the width direction Y of the first electrode, the first separator 24 can completely cover the first edge 2121 and at least a portion of the edge of the first active material layer away from the insulating layer 213. This reduces the risk of short circuit failure caused by the first edge 2121 and the edge of the first active material layer away from the insulating layer 213 piercing the separator 23 during drop and tumbling tests or after mechanical abuse such as drop and tumbling. This improves the safety of the battery cell 100 during drop and tumbling tests and under its operating conditions, and increases the pass rate of the battery cell 100 in drop and tumbling tests. It also reduces the problem of active material powdering of the second electrode 22 with the opposite polarity to the first electrode 21 caused by the thickness difference formed by the first separator 24, and even the problem of short circuit caused by tearing at the edge of the second electrode 22 and piercing the separator during cycling, thus improving the safety performance of the battery cell 100.

[0140] The dimension of the first separator 24 extending beyond the first active material layer 212 and away from the insulating layer 213 along the width direction Y of the first electrode sheet is set according to actual needs. For example, the dimension of the portion of the first separator 24 extending beyond the first active material layer 212 and away from the insulating layer 213 along the width direction Y of the first electrode sheet is H2, where H2 ≥ 1 mm.

[0141] For example, H2 can be 1mm, 1.2mm, 1.5mm, 1.7mm, 1.8mm, 2mm, 2.2mm, 2.5mm, 2.7mm, 3mm, etc.

[0142] By using H2≥1mm, it is easier to set the first separator 24, reducing the difficulty of the process. Also, the size of the first separator 24 extending beyond the first active material layer 212 away from the insulating layer 213 is larger, so as to better cover the edge of the first active material layer 212 away from the insulating layer 213. This allows the first separator 24 to separate the edge of the first active material layer 212 in the width direction Y of the first electrode sheet from the separator 23, reducing the risk of the first active material layer 212 piercing the separator 23 at the edge in the width direction Y of the first electrode sheet, thus improving the safety performance of the cell 100.

[0143] like Figure 8 As shown, in some embodiments, the second electrode 22 includes a second substrate 221 and a second active material layer 222. The second substrate 221 includes a second current collector 22111 and a second tab 22112. Along the thickness direction of the second electrode 22, at least one side of the second current collector 22111 is provided with the second active material layer 222. Along the width direction of the second electrode 22, the second tab 22112 includes a connected second empty foil portion 221122 and a flattened portion 221123. The second empty foil portion 221122 is connected to the end of the second current collector 22111 away from the first tab 2112, and the second flattened portion 221123 is connected to the end of the second empty foil portion 221122 away from the second current collector 22111. The first separator 24 is spaced apart from the second flattened portion 221123.

[0144] The second kneading section 221123 can be a structure formed by a kneading process or a flattening process.

[0145] Along the width direction of the second electrode 22, the first separator 24 can be spaced apart from any position of the second kneading portion 221123 facing the second connecting portion, or the first separator 24 can be spaced apart from a portion of the second kneading portion 221123 facing the second connecting portion.

[0146] When the second electrode 22 is in a wound state, the width direction of the second electrode 22 can be parallel to the width direction Y of the first electrode.

[0147] By spacing the first separator 24 and the second flattening portion 221123 along the width direction of the second electrode 22, the risk of the first separator 24 being damaged and thus failing to function during the process of forming the second flattening portion 221123 by flattening or patting is reduced.

[0148] In some embodiments, along the width direction Y of the first electrode, the dimension of the end of the first separator 24 extending beyond the first active material layer 212 and away from the insulating layer 213 is smaller than the dimension of the second empty foil portion 221122.

[0149] By making the portion of the first separator 24 extending beyond the first active material layer 212 and away from the insulating layer 213 smaller than the size of the second flattened portion 221123 along the width direction of the second electrode 22, the risk of the second flattened portion 221123 coming into contact with the first separator 24 is reduced. This is beneficial because the first separator 24 and the second flattened portion 221123 are spaced apart along the width direction of the second electrode 22, reducing the risk that the first separator 24 may be damaged and its function may fail during the process of forming the second flattened portion 221123 by flattening or patting.

[0150] like Figure 3 , Figures 6-7 , Figures 9-10 As shown, in some embodiments, along the winding direction X of the first electrode, the first separator 24 extends beyond the first winding end 21b.

[0151] Understandably, along the winding direction X of the first electrode, the first separator 24 extends beyond the first edge 2121 and the second edge 2131.

[0152] By extending the first separator 24 beyond the first winding end 21b, not only is the process of setting the insulation layer 213 easier to implement, but the first separator 24 also better covers the first edge 2121 and the second edge 2131. Thus, the first separator 24 can separate the separator 23 from the first edge 2121, as well as separate the separator 23 from the second edge 2131. This reduces the risk of the first edge 2121 and the second edge 2131 puncturing the separator 23 and causing short circuit failure during drop and roller tests or after mechanical abuse such as drop and roller tests. This improves the safety of the battery cell 100 during drop and roller tests and under drop and roller conditions, and increases the pass rate of the battery cell 100 in drop and roller tests.

[0153] Please continue to refer to Figure 3 , Figures 6-7 , Figures 9-10 In some embodiments, the size of the first separator 24 is W along the winding direction X of the first electrode sheet, where 3mm ≤ W ≤ 6mm.

[0154] For example, W can be 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, etc.

[0155] By using W≥3mm, the size of the first separator 24 is larger, which can better cover the first edge 2121 and the second edge 2131, reduce the risk of the first separator 24 warping after winding, and facilitate the connection between the first separator 24 and the first electrode 21. By using W≤6mm, the space occupied by the first separator 24 is reduced, and the energy density of the cell 100 is increased.

[0156] Please continue to refer to Figure 3 , Figures 6-7 , Figures 9-10 In some embodiments, along the winding direction X of the first electrode sheet, the first electrode sheet 21 has a first winding start end 21a, and the first separator 24 has a first end 24a close to the first winding start end 21a. The distance between the first end 24a and the first winding end 21b is W1, where 2mm≤W1≤3mm.

[0157] Along the winding direction X of the first electrode sheet, the portion of the first separator 24 located between the first end 24a and the first winding end 21b can be the portion where the first separator 24 is connected to the first active material layer 212. Then W1 is the dimension of the portion where the first separator 24 is connected to the first electrode sheet 21 in the winding direction X of the first electrode sheet.

[0158] In an embodiment where the first separator 24 is flush with the first winding termination end 21b, the first separator 24 between the first end 24a and the first winding termination end 21b is the entirety of the first separator 24 in the winding direction X of the first electrode. In an embodiment where the first separator 24 extends beyond the first winding termination end 21b along the winding direction X of the first electrode, it is only a portion of the first separator 24 in the winding direction X of the first electrode.

[0159] For example, W1 can be 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3mm, etc.

[0160] With W1≥2mm, the portion of the first separator 24 connected to the first electrode 21 is larger, which facilitates the connection between the first separator 24 and the first electrode 21, reduces the risk of the first separator 24 warping after winding, and improves the stability of the connection of the first separator 24; with W1≤3mm, the area of ​​the first active material layer 212 covered by the first separator 24 is reduced, as is the space occupied by the first separator 24, which increases the energy density of the cell 100. Therefore, 2mm≤W1≤3mm is beneficial to improving the connection stability of the first separator 24 and the energy density of the cell 100.

[0161] Please continue to refer to Figure 3 , Figures 6-7 , Figures 9-10 In some embodiments, the first separator 24 includes a first separator portion 241 and a second separator portion 242. The first separator portion 241 is located on one side of the thickness direction Z of the first electrode sheet and is connected to the first active material layer 212 to facilitate the fixing of the separator. The second separator portion 242 is the portion of the first separator 24 that extends beyond the first winding end 21b along the winding direction X of the first electrode sheet.

[0162] The second partition 242 is connected to the first partition 241, and the first partition 241 and the second partition 242 can be separate structures that are then connected into one.

[0163] The first partition 241 and the second partition 242 can also be integrally formed to form the first partition 24 with an integrally formed structure, which facilitates the manufacturing of the first partition 24 and gives the first partition 24 better structural performance.

[0164] The thickness of the second partition 242 can be the same as or different from the thickness of the first partition 241. When the first electrode 21 is in the unfolded state, along the thickness direction Z of the first electrode, the surface of the first partition 241 facing away from the first electrode 21 and the surface of the second partition 242 facing away from the first electrode 21 can be flush, and the surface of the first partition 241 facing the first electrode 21 and the surface of the second partition 242 facing the first electrode 21 can be flush. Therefore, the thickness of the first partition 241 and the thickness of the second partition 242 are the same.

[0165] When the first electrode 21 is in the unfolded state, along the thickness direction Z of the first electrode, the surfaces of the first partition 241 and the second partition 242 facing away from the first electrode 21 can be flush, while the surfaces of the first partition 241 and the second partition 242 facing the first electrode 21 can be non-flush. Therefore, the thicknesses of the first partition 241 and the second partition 242 are different. For example, as... Figure 7 , Figure 9 , Figure 10 As shown, when the first electrode 21 is in the unfolded state, along the thickness direction Z of the first electrode, the surface of the first partition 241 facing away from the first electrode 21 and the surface of the second partition 242 facing away from the first electrode 21 can be flush. The second partition 242 protrudes from the surface of the first partition 241 facing the first electrode 21, so the thickness of the second partition 242 is greater than the thickness of the first partition 241.

[0166] In some embodiments, the second dividing portion 242 is connected to the first winding termination end 21b. Specifically, the surface of the second dividing portion 242 facing the first winding termination end 21b is connected to the first winding termination end 21b.

[0167] The second dividing section 242 and the first winding end 21b can be connected by means of bonding or other methods.

[0168] The second separator 242 connects to the first winding end 21b via its surface facing the first winding end 21b, enabling the first separator 24 to better separate the edge of the first winding end 21b from the separator film 23. This also improves the stability of the connection between the first separator 24 and the first electrode 21, thereby further enhancing the safety performance of the cell 100.

[0169] like Figure 3 , Figures 6-10 As shown, in some embodiments, along the thickness direction Z of the first electrode sheet, both sides of the first substrate 211 are provided with a first active material layer 212 and an insulating layer 213; the electrode assembly 20 includes two first separators 24, the first separation portions 241 of the two first separators 24 are respectively located on both sides of the first electrode sheet 21, and the two second separation portions 242 are connected beyond the first winding end 21b.

[0170] With a first active material layer 212 and an insulating layer 213 disposed on both sides of the first substrate 211, the electrode assembly 20 includes two first separators 24, which can cover the two opposite edges of the first winding end 21b in the thickness direction, that is, can cover the first edges 2121 of the two first active material layers 212 and the second edges 2131 of the two insulating layers 213. The first separators 24 can separate each first edge 2121 from the separator 23 and each second edge 2131 from the separator 23, reducing the risk of the first edge 2121 and the second edge 2131 puncturing the separator 23. Furthermore, the second dividing portions 242 of both first separators 24 extend beyond the first winding. The two first separators 24 are connected around the first winding end 21b and can completely separate the first winding end 21b and the separator 23, so that the two first separators 24 can form a closed space at the first winding end 21b. This allows the two first separators 24 to more stably separate the edge of the first winding end 21b and the separator 23, thereby reducing the risk that the edge of the positive terminal of the cell 100 will puncture the separator 23 during drop tests or when the cell is in a drop condition. This improves the safety of the cell 100 and the pass rate of drop, roller and other tests. It also makes the connection between the first separator 24 and the first electrode 21 more stable and reduces the risk that the first separator 24 will detach from the first electrode 21.

[0171] The second separating portions 242 of the two first separating members 24 can be connected. Specifically, the two opposing surfaces of the second separating portions 242 of the two first separating members 24 are connected in the thickness direction Z of the first electrode. The second separating portions 242 of the two first separating members 24 can be connected by means of bonding, welding, or other methods.

[0172] The second separating portions 242 of the two first separating members 24 are connected, reducing the risk of the first separating member 24 detaching from the first electrode 21. It also enables the two first separating members 24 to form a stable closed space at the first winding end 21b, thereby enabling the first separating member 24 to more stably separate the edge of the first winding end 21b from the separator 23. This reduces the risk of the edge of the first winding end 21b puncturing the separator 23 when the cell 100 is in a drop test or under drop conditions, and improves the safety of the cell 100 and the pass rate of drop, roller and other tests.

[0173] Of course, in other embodiments, the second partitions 242 of the two first partitions 24 may be in contact or have a gap.

[0174] Combined with reference Figure 3 , Figure 7 In an embodiment where the outermost electrode of the electrode assembly 20 is a second electrode 22, and the outermost portion of the second electrode 22 is located outside the first winding termination end 21b and extends beyond the first winding termination end 21b along the winding direction X of the first electrode, since the second partition portions 242 of the two first partitions 24 extend beyond the first winding termination end 21b, the two second partition portions 242 fill the space between the first winding termination end 21b and the portion of the outermost edge of the second electrode 22 extending beyond the first winding termination end 21b, and also fill the space of the outermost edge of the second electrode 22 extending beyond the first winding termination end 21b. The gap on the side of the portion around the end 21b closest to the first winding end 21b improves the uniformity of the force between the electrode assembly 20 and the outer shell 10 when the electrode assembly 20 expands, reduces the risk of the electrode assembly 20 sinking due to the force of the outer shell 10, or alleviates the degree of sinking of the electrode assembly 20 after expansion due to the force of the outer shell 10. This reduces the risk of short circuit failure caused by the electrode assembly 20 sinking and puncturing the separator 23 during drop mechanical testing or when the cell 100 is in a drop condition, further improving the yield and safety performance of the cell 100.

[0175] like Figures 11-16 As shown, the first electrode 21 has a first winding start end 21a, the first active material layer 212 has a third edge 2122 located at the first winding start end 21a, and the insulating layer 213 has a fourth edge 2132 near the first winding start end 21a.

[0176] In the winding direction X of the first electrode, one end of the first active material layer 212 is located at the first winding start end 21a. Understandably, one end of the first active material layer 212 is a part of the first winding start end 21a. The third edge 2122 of the first active material layer 212 forms at least a portion of an edge of the first winding start end 21a in the thickness direction Z of the first electrode.

[0177] The fourth edge 2132 is an edge of the insulating layer 213 near the first winding start end 21a. The fourth edge 2132 can be located at the first winding start end 21a. Understandably, one end of the insulating layer 213 is part of the first winding start end 21a, and the fourth edge 2132 of the insulating layer 213 forms part of an edge of the first winding start end 21a in the thickness direction Z of the first electrode. Of course, along the winding direction X of the first electrode, the fourth edge 2132 can be at a distance from the first winding start end 21a.

[0178] Please continue to refer to Figures 11-16 In some embodiments, the electrode assembly 20 further includes a second separator 25, which is connected to the surface of the first active material layer 212 facing away from the first substrate 211 and the surface of the insulating layer 213 facing away from the first substrate 211, and the second separator 25 covers the third edge 2122 and the fourth edge 2132.

[0179] The second separator 25 can be made of insulating material to reduce the risk of short circuit in the cell 100. The second separator 25 can also be made of a softer material to reduce the risk of the first separator 24 puncturing the separator membrane 23.

[0180] For example, the second separator 25 includes adhesive tape. The adhesive tape has good flexibility, and the inclusion of adhesive tape in the second separator 25 facilitates winding after it is connected to the first electrode 21, and reduces the risk of the second separator 25 warping at the edges after winding. Furthermore, the adhesive tape form of the second separator 25 facilitates the connection between the second separator 25 and the first electrode 21. The material of the adhesive tape used as the second separator 25 can be the same as or different from the material of the adhesive tape used as the first separator 24.

[0181] The second separator 25 may be the surface of the first active material layer 212 that faces away from the first substrate 211.

[0182] Along the winding direction X of the first electrode sheet, one end of the second separator 25 may be flush with the third edge 2122 or the second separator 25 may extend beyond the third edge 2122, so that the second separator 25 covers the third edge 2122.

[0183] Along the winding direction X of the first electrode, one end of the second separator 25 may be flush with the fourth edge 2132 or the second separator 25 may extend beyond the fourth edge 2132, so that the second separator 25 covers the fourth edge 2132.

[0184] The second active material layer 222 has a third edge 2122 located at the first winding start end 21a, and the insulating layer 213 has a fourth edge 2132 near the first winding start end 21a. The third edge 2122 and the fourth edge 2132 are covered by the second separator 25. The second separator 25 can separate the separator 23 from the third edge 2122 and the fourth edge 2132, thereby reducing the risk of the third edge 2122 and the fourth edge 2132 puncturing the separator 23 and causing short circuit failure during drop and roller tests or after mechanical abuse such as drop and roller tests. This improves the safety of the cell 100 during drop and roller tests and under its operating conditions, and increases the pass rate of the cell 100 in drop and roller tests.

[0185] The structure of the second separator 25, as well as the connection and relative position relationship between the second separator 25 and the first electrode 21, can be referred to the relationship between the first separator 24 and the first electrode 21, and will not be repeated here.

[0186] This application also provides an electrical device, which includes the battery cell 100 provided in any of the above embodiments.

[0187] The battery cell 100 provided in any of the above embodiments has good safety performance and can improve the power safety and reliability of electrical equipment powered by the battery cell 100.

[0188] 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, characterized in that, The electrode assembly includes an electrode assembly with a wound structure. The electrode assembly includes a first electrode sheet, which includes a first substrate, a first active material layer, and an insulating layer. Along the thickness direction of the first electrode sheet, at least one surface of the first substrate is provided with the first active material layer and the insulating layer. The first substrate includes a first current collector and a first tab. Along the width direction of the first electrode sheet, the first tab is connected to one end of the first current collector. The first active material layer covers at least a portion of the first current collector, and the insulating layer covers at least a portion of the first tab. Along the winding direction of the first electrode, the first electrode has a first winding end, the first active material layer has a first edge located at the first winding end, and the insulating layer has a second edge close to the first winding end. The electrode assembly further includes a first separator, which is connected to the surface of the first active material layer opposite to the first substrate and the surface of the insulating layer opposite to the first substrate, and the first separator covers the first edge and the second edge.

2. The battery cell according to claim 1, characterized in that, Along the width direction of the first electrode, the first separator extends beyond the insulating layer at the end away from the first active material layer.

3. The battery cell according to claim 2, characterized in that, The first electrode tab includes a first connecting portion covered by the insulating layer, a first empty foil portion not covered by the insulating layer, and a first flattened portion. Along the width direction of the first electrode sheet, the first connecting portion is connected to one end of the first current collector, the first empty foil portion is located between the first connecting portion and the first flattened portion, and connects the first connecting portion and the first flattened portion, and the first separator is spaced apart from the first flattened portion.

4. The battery cell according to claim 2 or 3, characterized in that, The first electrode tab includes a first connecting portion covered by the insulating layer, a first empty foil portion not covered by the insulating layer, and a first flattened portion. Along the width direction of the first electrode sheet, the first connecting portion is connected to one end of the first current collector, and the first empty foil portion is located between the first connecting portion and the first flattened portion, and connects the first connecting portion and the first flattened portion. Along the width direction of the first electrode, the size of the portion of the first separator extending beyond the insulating layer away from the first active material layer is smaller than the size of the first empty foil portion.

5. The battery cell according to claim 3 or 4, characterized in that, The first separator is connected to the surface of the first active material layer away from the first current collector, the surface of the insulating layer away from the first electrode tab, and the surface of the first empty foil portion in the thickness direction.

6. The battery cell according to claim 5, characterized in that, Along the thickness direction of the first electrode, the surface of the first separator facing away from the first substrate includes a first region, a second region, and a third region connected in sequence. The first region is disposed corresponding to the first active material layer, the second region is disposed corresponding to the insulating layer, and the third region is disposed corresponding to the first empty foil portion. The distance between the first region and the first substrate is D1, the distance between the second region and the first substrate is D2, and the distance between the third region and the first substrate is D3. |D1-D2|≤5μm, |D1-D3|≤5μm.

7. The battery cell according to any one of claims 2-6, characterized in that, Along the width direction of the first electrode, the dimension of the portion of the first separator extending beyond the insulating layer away from the first active material layer is H1, where 1mm≤H1≤3mm.

8. The battery cell according to any one of claims 1-7, characterized in that, Along the winding direction of the first electrode, the first separator extends beyond the first winding end.

9. The battery cell according to claim 8, characterized in that, Along the thickness direction of the first electrode sheet, the first active material layer and the insulating layer are provided on both sides of the first substrate; The electrode assembly includes two first separators, each comprising a first dividing portion and a second dividing portion. The first dividing portions of the two first separators are located on both sides of the first electrode sheet, and the two second dividing portions extend beyond the first winding end and are connected.

10. The battery cell according to claim 9, characterized in that, The surface of the second dividing portion facing the first winding end is connected to the first winding end.

11. The battery cell according to any one of claims 1-10, characterized in that, Along the winding direction of the first electrode, the size of the first separator is W, where 3mm ≤ W ≤ 6mm.

12. The battery cell according to any one of claims 1-11, characterized in that, Along the winding direction of the first electrode, the first electrode has a first winding start end, the first separator has a first end close to the first winding start end, and the distance between the first end and the first winding end is W1, 2mm≤W1≤3mm.

13. The battery cell according to any one of claims 1-12, characterized in that, Along the width direction of the first electrode, the first separator extends beyond the end of the first active material layer away from the insulating layer.

14. The battery cell according to any one of claims 1-13, characterized in that, The electrode assembly further includes a second electrode, which has the opposite polarity to the first electrode. The second electrode includes a second substrate and a second active material layer. The second substrate includes a second current collector and a second tab. Along the thickness direction of the second electrode, at least one side of the second current collector is provided with the second active material layer. Along the width direction of the second electrode, the second tab includes a connected second empty foil portion and a flattened portion. The second empty foil portion is connected to the end of the second current collector away from the first tab, and the second flattened portion is connected to the end of the second empty foil portion away from the second current collector. The first separator is spaced apart from the second flattened portion.

15. The battery cell according to claim 14, characterized in that, Along the width direction of the first electrode, the dimension of the first separator extending beyond the first active material layer and away from the insulating layer is smaller than the dimension of the second empty foil portion.

16. The battery cell according to claim 15, characterized in that, Along the width direction of the first electrode, the dimension of the first separator extending beyond the first active material layer away from the insulating layer is H2, where H2 ≥ 1 mm.

17. The battery cell according to any one of claims 1-16, characterized in that, Along the winding direction of the first electrode, the size of the first current collector is L1, the size of the first electrode tab is L2, and 0.5≤L2 / L1≤1.

18. The battery cell according to any one of claims 1-17, characterized in that, The first separator includes adhesive tape.

19. The battery cell according to any one of claims 1-18, characterized in that, The first electrode has a first winding start end, the first active material layer has a third edge located at the first winding start end, and the insulating layer has a fourth edge close to the first winding start end. The electrode assembly further includes a second separator, which is connected to the surface of the first active material layer opposite to the first substrate and the surface of the insulating layer opposite to the first substrate, and the second separator covers the third edge and the fourth edge.

20. The battery cell according to any one of claims 1-19, characterized in that, The first electrode is a positive electrode.

21. The battery cell according to claim 20, characterized in that, The electrode assembly further includes a second electrode, which is a negative electrode. The second electrode extends beyond the first winding end along the winding direction of the first electrode. The first separator is provided on any side of the first winding end facing the second electrode.

22. An electrical appliance, characterized in that, Includes the battery cell according to any one of claims 1-21.

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