Battery monomer, battery and electric equipment

Abstract

The embodiment of the utility model provides a battery monomer, a battery and electric equipment. The battery cell includes an electrode assembly of a wound structure. The electrode assembly comprises a negative pole piece and a positive pole piece, the negative pole piece comprises a negative current collector and a negative active material layer, and the positive pole piece comprises a positive current collector and a positive active material layer. The negative pole piece comprises a first bending section, the positive pole piece comprises a second bending section, the first bending section and the second bending section are adjacently arranged, and the second bending section is positioned on the outer side of the first bending section. The negative current collector comprises a first body part and a first concave part, the first concave part is filled with the negative active material layer, and the first concave part is formed in the first bending section. The positive current collector comprises a second body part and a first convex part, the positive active material layer wraps the first convex part, and the second bending section is provided with the first convex part. According to the technical scheme, the reliability of the battery can be improved.

Description

Technical Field

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

[0002] Energy conservation and emission reduction are the key to the sustainable development of the automobile industry. Electric vehicles have become an important part of the sustainable development of the automobile industry due to their advantages in energy conservation and environmental protection. For electric vehicles, battery technology is an important factor in their development.

[0003] In the development of battery technology, how to improve battery reliability is a technical problem that needs to be solved urgently. Utility Model Content

[0004] The present application provides a battery cell, a battery and an electrical device, which can improve the reliability of the battery.

[0005] This application is achieved through the following technical solutions:

[0006] In a first aspect, the present application provides a battery cell, including an electrode assembly. The electrode assembly is a wound structure, and the electrode assembly includes a straight region and a bending region connected to the straight region. The electrode assembly includes a negative electrode sheet and a positive electrode sheet, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on the surface of the negative electrode current collector, and the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on the surface of the positive electrode current collector. Among them, the negative electrode electrode sheet includes a first bending section located in the bending area, the negative electrode current collector includes a first main body and at least one first recess, the first recess is formed on the outer surface of the first main body, the negative active material layer fills the first recess, and the first bending section is provided with at least one first recess; and / or, the positive electrode electrode sheet includes a second bending section located in the bending area, the first bending section and the second bending section are corresponding and adjacently arranged, the second bending section is located on the outside of the first bending section, the positive electrode current collector includes a second main body and at least one first convex portion, the first convex portion protrudes from the inner surface of the second main body, the positive active material layer wraps the first convex portion, and the second bending section is provided with at least one first convex portion.

[0007] The technical solution of the embodiment of the present application is to form a first concave portion on the outer surface of the first main body of the negative electrode current collector, the negative electrode active material layer is filled in the first concave portion, and the first bending portion is provided with at least one first concave portion, so that the negative electrode active material on the first bending portion in the bending area is increased, thereby reducing the risk of lithium deposition in the bending area, improving the reliability of the battery cell, and improving the reliability of the battery. A first convex portion is formed on the inner surface of the second main body of the positive electrode current collector, the positive electrode active material layer wraps the first convex portion, and the second bending portion is provided with at least one first convex portion. The positive electrode active material on the second bending portion in the bending area is reduced, thereby reducing the risk of lithium deposition in the bending area, improving the reliability of the battery cell, and improving the reliability of the battery.

[0008] In some embodiments, when the negative electrode sheet is unfolded, the outer surface of the region corresponding to the negative electrode active material layer and the first body portion is coplanar with the outer surface of the region corresponding to the negative electrode active material layer and the first recess.

[0009] According to the technical solution of the embodiment of the present application, the first recess is formed on the outer surface of the first main body, the negative electrode active material layer fills the first recess, and the outer surface of the negative electrode active material layer and the outer surface of the area corresponding to the first main body are coplanar with the outer surface of the negative electrode active material layer and the outer surface of the area corresponding to the first recess, so that the negative electrode active material on the outer surface of the area corresponding to the first main body is increased, thereby reducing the risk of lithium deposition on the bending zone, improving the reliability of the battery cell, and improving the reliability of the battery.

[0010] In some embodiments, the thickness of the negative electrode current collector at the first recess is greater than 0 and less than or equal to 0.8 times the thickness of the first body portion.

[0011] According to the technical solution of the embodiment of the present application, the thickness of the negative electrode current collector at the first recess meets the above conditions, which reduces the risk of breakage of the negative electrode plate during winding, and at the same time reduces the risk of lithium deposition on the bending area, thereby improving the reliability of the battery cell and the reliability of the battery.

[0012] In some embodiments, the thickness of the negative electrode current collector at the first recess is greater than 0 and less than or equal to 0.5 times the thickness of the first body portion.

[0013] According to the technical solution of the embodiment of the present application, the thickness of the negative electrode current collector at the first recess meets the above conditions, which further reduces the risk of breakage of the negative electrode plate during winding, and at the same time reduces the risk of lithium deposition on the bending area, thereby improving the reliability of the battery cell and the reliability of the battery.

[0014] In some embodiments, the first bending section is located at the innermost circle of the negative electrode plate.

[0015] According to the technical solution of the embodiment of the present application, the first bending section is located at the innermost circle of the negative electrode plate, which reduces the risk of lithium deposition in the innermost bending area, improves the reliability of the battery cell, and improves the reliability of the battery.

[0016] In some embodiments, at least a portion of the first recess is located in the first bending segment.

[0017] According to the technical solution of the embodiment of the present application, at least part of the first recess is located in the first bending section, which reduces the risk of lithium deposition in the first bending section corresponding to the first recess, improves the reliability of the battery cell, and improves the reliability of the battery.

[0018] In some embodiments, the negative electrode plate includes a first straight section and a second straight section located in the straight area. The first straight section, the first bent section and the second straight section are arranged in sequence along the winding direction. Along the winding direction, one end of the first recess is located in the first straight section, and the other end of the first recess is located in the second straight section.

[0019] According to the technical solution of the embodiment of the present application, the first recess exists in all parts of the first bending section, which reduces the risk of lithium deposition in the first bending section, improves the reliability of the battery cell, and improves the reliability of the battery.

[0020] In some embodiments, when the positive electrode sheet is unfolded, the inner surface of the region corresponding to the positive electrode active material layer and the second body portion is coplanar with the inner surface of the region corresponding to the positive electrode active material layer and the first protrusion portion.

[0021] According to the technical solution of the embodiment of the present application, the first convex portion is formed on the inner surface of the second main body portion, the positive electrode active material layer wraps the first convex portion, and the inner surface of the positive electrode active material layer and the inner surface of the area corresponding to the second main body portion and the inner surface of the positive electrode active material layer and the inner surface of the area corresponding to the first convex portion are coplanar, so that the positive electrode active material on the inner surface of the area corresponding to the second main body portion is reduced, thereby reducing the risk of lithium deposition on the bending area, improving the reliability of the battery cell, and improving the reliability of the battery.

[0022] In some embodiments, the thickness of the positive electrode current collector at the first protrusion is greater than the thickness of the second body portion, and less than or equal to 6 times the thickness of the second body portion.

[0023] According to the technical solution of the embodiment of the present application, the thickness of the positive electrode current collector at the first protrusion meets the above conditions, which reduces the risk of breakage of the positive electrode sheet during winding, and at the same time reduces the risk of lithium deposition on the bending area, thereby improving the reliability of the battery cell and the reliability of the battery.

[0024] In some embodiments, the thickness of the positive electrode current collector at the first protrusion is greater than the thickness of the second body portion, and less than or equal to 3 times the thickness of the second body portion.

[0025] According to the technical solution of the embodiment of the present application, the thickness of the positive electrode current collector at the first protrusion meets the above conditions, which further reduces the risk of breakage of the positive electrode sheet during winding, and at the same time reduces the risk of lithium deposition on the bending area, thereby improving the reliability of the battery cell and the reliability of the battery.

[0026] In some embodiments, the second bent section is located at the innermost circle of the positive electrode plate.

[0027] According to the technical solution of the embodiment of the present application, the second bending section is located at the innermost circle of the positive electrode plate, which reduces the risk of lithium deposition in the innermost bending area, improves the reliability of the battery cell, and improves the reliability of the battery.

[0028] In some embodiments, at least a portion of the first protrusion is located in the second bending segment.

[0029] According to the technical solution of the embodiment of the present application, at least part of the first convex portion is located in the second bending section, thereby reducing the risk of lithium deposition in the second bending section corresponding to the first convex portion, improving the reliability of the battery cell, and improving the reliability of the battery.

[0030] In some embodiments, the positive electrode plate includes a third straight segment and a fourth straight segment located in the straight area, and the third straight segment, the second bent segment and the fourth straight segment are arranged in sequence along the winding direction. Along the winding direction, one end of the first protrusion is located in the third straight segment, and the other end of the first protrusion is located in the fourth straight segment.

[0031] According to the technical solution of the embodiment of the present application, the first convex portion exists in all parts of the second bending section, which reduces the risk of lithium plating in the second bending section, improves the reliability of the battery cell, and improves the reliability of the battery.

[0032] In some embodiments, along the winding direction, the first concave portion has a first end and a second end, and the first convex portion has a third end and a fourth end. In the winding direction, the first end exceeds the third end. In the opposite direction of the winding direction, the fourth end exceeds the second end.

[0033] According to the technical solution of the embodiment of the present application, in the winding direction, the first end exceeds the third end; in the opposite direction of the winding direction, the fourth end exceeds the second end, so that the first convex portion corresponds to at least a portion of the first concave portion, reducing the risk of lithium plating in the first bending section, improving the reliability of the battery cell, and improving the reliability of the battery.

[0034] In a second aspect, the embodiments of the present application further provide a battery, comprising a battery cell as in any one of the embodiments of the first aspect.

[0035] In a third aspect, an embodiment of the present application further provides an electrical device, comprising a battery cell as in any embodiment of the first aspect or a battery as in any embodiment of the second aspect, wherein the battery cell or the battery is used to provide electrical energy.

[0036] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 A schematic diagram of the structure of a vehicle provided in some embodiments of the present application;

[0039] Figure 2 A schematic diagram of the structure of a battery provided in some embodiments of the present application;

[0040] Figure 3 A schematic diagram of the structure of a battery cell provided in some embodiments of the present application;

[0041] Figure 4 A schematic diagram of an electrode assembly provided for some embodiments of the present application;

[0042] Figure 5 Schematic diagrams of electrode assemblies provided for other embodiments of the present application;

[0043] Figure 6 Schematic diagram of electrode assemblies provided in some other embodiments of the present application;

[0044] Figure 7 A partial schematic diagram of an electrode assembly provided in some embodiments of the present application;

[0045] Figure 8 A schematic diagram of a negative electrode sheet provided in some embodiments of the present application;

[0046] Fig. 9 A schematic diagram of a negative electrode current collector provided in some embodiments of the present application;

[0047] Fig.10 A schematic diagram of a positive electrode sheet provided in some embodiments of the present application;

[0048] Fig.11 A schematic diagram of a positive electrode current collector provided in some embodiments of the present application;

[0049] Fig.12 A partial schematic diagram of an electrode assembly provided for some other embodiments of the present application.

[0050] Icons: 1-battery cell; 10-electrode assembly; 11-bending area; 12-straight area; 13-negative electrode plate; 131-negative current collector; 1311-first body; 1312-first recess; 1313-first end; 1314-second end; 132-negative active material layer; 133-first bending section; 134-first straight section; 135-second straight section; 14-positive electrode plate; 141-positive current collector; 1411-second body; 1412 -first convex portion; 1413-third end; 1414-fourth end; 142-positive electrode active material layer; 143-second bent section; 144-third straight section; 145-fourth straight section; 15-diaphragm; 20-housing; 21-end cover; 22-shell; 30-electrode terminal; 100-battery; 110-case; 120-first sub-case; 130-second sub-case; 1000-vehicle; 1100-controller; 1200-motor; X-winding direction. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0052] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as those commonly understood by technicians in the technical field of this application; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned drawings and any variations thereof are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship.

[0053] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0054] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "attached" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0055] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the associated objects before and after are in an "or" relationship.

[0056] The term "multiple" as used in this application refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple sheets" refers to more than two sheets (including two sheets).

[0057] In some embodiments, the battery may be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0058] In some embodiments, the battery may be a battery pack, which includes a case and battery cells, wherein the battery cells or battery modules are accommodated in the case.

[0059] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0060] In some embodiments, the battery may be an energy storage device, which includes an energy storage container, an energy storage cabinet, and the like.

[0061] In the embodiment of the present application, the battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0062] The battery cells may be, but are not limited to, lithium ion batteries, sodium ion batteries, sodium lithium ion batteries, lithium metal batteries, sodium metal batteries, lithium sulfur batteries, magnesium ion batteries, nickel hydrogen batteries, nickel cadmium batteries, lead storage batteries, etc.

[0063] As an example, the battery cell may be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes, the prismatic battery cell including a square case battery cell.

[0064] A battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are embedded and removed between the positive electrode and the negative electrode. The separator is set between the positive electrode and the negative electrode to prevent the positive and negative electrodes from short-circuiting, while allowing active ions to pass through.

[0065] In some embodiments, the positive electrode may be a positive electrode sheet, and the positive electrode sheet may include a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector.

[0066] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material layer is disposed on any one or both of the two facing surfaces of the positive electrode current collector.

[0067] As an example, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc., may be used. The composite current collector may include a polymer material base and a metal layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0068] As an example, the positive electrode active material layer may include at least one of the following materials: lithium-containing phosphate, lithium transition metal oxide and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active material layers of batteries may also be used.

[0069] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector.

[0070] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active layer is disposed on any one or both of the two facing surfaces of the negative electrode current collector.

[0071] As an example, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. may be used.

[0072] In some embodiments, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode active material layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0073] As an example, the negative electrode active material layer may adopt materials known in the art. As an example, the negative electrode active material layer may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active material layers of batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0074] In some embodiments, the separator is a membrane. The present application has no particular limitation on the type of the membrane, and any known porous membrane with good chemical stability and mechanical stability can be selected.

[0075] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator can be a single-layer film or a multi-layer composite film, without special restrictions. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without special restrictions. The separator can be a separate component located between the positive and negative electrodes, or it can be attached to the surface of the positive and negative electrodes.

[0076] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transmit ions and isolate the positive and negative electrodes.

[0077] In some embodiments, the electrode assembly is a wound structure, wherein the positive electrode sheet and the negative electrode sheet are wound into a wound structure.

[0078] At present, from the perspective of market development, batteries have been widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as electric tools, drones, energy storage equipment, etc. With the continuous expansion of battery application areas, the market demand is also constantly expanding.

[0079] The development of battery technology must take into account many design factors at the same time, such as energy density, cycle life, discharge capacity, charge and discharge rate and other performance parameters. In addition, as environmental conditions and / or battery internal conditions change, battery reliability is also one of the key factors to consider.

[0080] At present, during the use of battery cells, such as during charging and discharging, taking the battery cells as lithium-ion batteries as an example, in the bending area of ​​the electrode assembly, the first bending section of the negative electrode sheet and the second bending section of the positive electrode sheet are adjacent, and the second bending section is located on the outside of the first bending section, so that the positive electrode active material layer on the inner surface of the second bending section is more than the negative electrode active material layer on the outer surface of the first bending section, making the electrode assembly prone to lithium deposition, thereby affecting the use of the lithium-ion battery or affecting the service life of the lithium-ion battery, thereby affecting the reliability of the battery.

[0081] Based on the above considerations, in order to reduce the problem of lithium deposition in the bending zone of the electrode assembly, which leads to poor reliability of the battery cell and the battery, an embodiment of the present application provides a battery cell, including a wound electrode assembly. The electrode assembly includes a negative electrode plate and a positive electrode plate, the negative electrode plate includes a negative electrode collector and a negative electrode active material layer arranged on the surface of the negative electrode collector, and the positive electrode plate includes a positive electrode collector and a positive electrode active material layer arranged on the surface of the positive electrode collector. The negative electrode plate includes a first bending section located in the bending zone, and the positive electrode plate includes a second bending section located in the bending zone, the first bending section and the second bending section are arranged correspondingly and adjacently, and the second bending section is located outside the first bending section.

[0082] The negative electrode current collector comprises a first main body and at least one first recess, wherein the first recess is formed on the outer surface of the first main body, the negative electrode active material layer fills the first recess, and the first bending section is provided with at least one first recess.

[0083] And / or, the positive electrode current collector includes a second main body and at least one first convex portion, the first convex portion protrudes from the inner surface of the second main body, the positive electrode active material layer wraps the first convex portion, and the second bending section is provided with at least one first convex portion.

[0084] A first recess is formed on the outer surface of the first main body of the negative electrode current collector, and / or a first protrusion is formed on the inner surface of the positive electrode current collector, so that in the bending zone, the negative electrode active material on the first bending portion increases and / or the positive electrode active material on the second bending portion decreases, thereby reducing the risk of lithium deposition in the bending zone, improving the reliability of the battery cell, and improving the reliability of the battery.

[0085] The battery disclosed in the embodiments of the present application can be used, but is not limited to, in electrical equipment such as vehicles, ships or aircraft. The battery disclosed in the present application can also be used to form a power supply system for the electrical equipment.

[0086] The embodiment of the present application provides an electric device using a battery as a power source, and the electric device may be, but is not limited to, a mobile phone, a tablet computer, a laptop computer, an electric toy, an electric tool, an electric bicycle, an electric motorcycle, an electric car, a ship, a spacecraft, etc. Among them, the electric toy may include a fixed or mobile electric toy, for example, a game console, an electric car toy, an electric ship toy, an electric airplane toy, etc., and the spacecraft may include an airplane, a rocket, a space shuttle, a spacecraft, etc.

[0087] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device in an embodiment of the present application.

[0088] Please refer to Figure 1 , Figure 1 A schematic diagram of the structure of a vehicle provided for some embodiments of the present application. Vehicle 1000 may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 may be provided at the bottom, head or tail of the vehicle 1000. The battery 100 may be used to power the vehicle 1000, for example, the battery 100 may be used as an operating power source for the vehicle 1000, for the circuit system of the vehicle 1000, for example, for the working power requirements during the startup, navigation and operation of the vehicle 1000.

[0089] The vehicle 1000 may further include a controller 1100 and a motor 1200 , wherein the controller 1100 is used to control the battery 100 to supply power to the motor 1200 , for example, to meet the power requirements of starting, navigating, and driving the vehicle 1000 .

[0090] In some embodiments of the present application, the battery 100 can not only serve as an operating power source for the vehicle 1000, but also serve as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0091] Please refer to Figure 2 , Figure 2A schematic diagram of the structure of a battery provided in some embodiments of the present application. The battery 100 may also include a housing 110, in which the battery cell 1 is accommodated. The housing 110 is used to provide a storage space for the battery cell 1, and the housing 110 may adopt a variety of structures. In some embodiments, the housing 110 may include a first sub-housing 120 and a second sub-housing 130, the first sub-housing 120 and the second sub-housing 130 cover each other, and the first sub-housing 120 and the second sub-housing 130 jointly define a storage space for accommodating the battery cell 1. The second sub-box 130 may be a hollow structure with one end open, and the first sub-box 120 may be a plate-like structure, and the first sub-box 120 covers the open side of the second sub-box 130, so that the first sub-box 120 and the second sub-box 130 jointly define a storage space; the first sub-box 120 and the second sub-box 130 may also be hollow structures both with one side open, and the open side of the first sub-box 120 covers the open side of the second sub-box 130.

[0092] In the battery 100, there may be multiple battery cells 1, and the multiple battery cells 1 may be connected in series, in parallel, or in a mixed connection. A mixed connection means that the multiple battery cells 1 are both connected in series and in parallel. The multiple battery cells 1 may be directly connected in series, in parallel, or in a mixed connection, and then the whole formed by the multiple battery cells 1 is accommodated in the box 110; of course, the battery 100 may also be a battery 100 module formed by connecting multiple battery cells 1 in series, in parallel, or in a mixed connection, and then the multiple battery 100 modules are connected in series, in parallel, or in a mixed connection to form a whole, and accommodated in the box 110. The battery 100 may also include other structures, for example, the battery 100 may also include a busbar component for realizing electrical connection between the multiple battery cells 1.

[0093] The battery cell 1 may be a secondary battery or a primary battery; the battery cell 1 may also be a lithium-sulfur battery, a sodium-ion battery or a magnesium-ion battery, but is not limited thereto.

[0094] Please refer to Figure 3 , Figure 3 This is a schematic diagram of the structure of a battery cell provided in some embodiments of the present application. Figure 3 As shown, the battery cell 1 includes a housing 20, an electrode assembly 10 and an electrode terminal 30. The housing 20 includes a shell 22 and an end cap 21. The shell 22 has an opening, and the end cap 21 closes the opening to isolate the internal environment of the battery cell 1 from the external environment.

[0095] The shell 22 is a component used to cooperate with the end cap 21 to form an internal environment of the battery cell 1, wherein the formed internal environment can be used to accommodate the electrode assembly 10, the electrolyte and other components. The shell 22 and the end cap 21 can be independent components. The shell 22 can be of various shapes and sizes. Specifically, the shape of the shell 22 can be determined according to the specific shape and size of the electrode assembly 10. The material of the shell 22 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0096] The end cap 21 refers to a component that covers the opening of the shell 22 to isolate the internal environment of the battery cell 1 from the external environment. Without limitation, the shape of the end cap 21 can be adapted to the shape of the shell 22 to match the shell 22. Optionally, the end cap 21 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that the end cap 21 is not easily deformed when squeezed and collided, so that the battery cell 1 can have a higher structural strength and reliability can also be improved. Functional components such as electrode terminals can be provided on the end cap 21. The electrode terminal can be used to electrically connect to the electrode assembly 10 for outputting or inputting electrical energy of the battery cell 1. The material of the end cap 21 can also be a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application are not particularly limited to this. In some embodiments, an insulating structure can also be provided on the inner side of the end cap 21, and the insulating structure can be used to isolate the electrical connection components in the shell 22 from the end cap 21 to reduce the risk of short circuit. Exemplarily, the insulating structure can be plastic, rubber, etc.

[0097] Please refer to Figures 4 to 7 , Figure 4 A schematic diagram of an electrode assembly provided in some embodiments of the present application, Figure 5 Schematic diagrams of electrode assemblies provided in some other embodiments of the present application, Figure 6 Schematic diagram of electrode assemblies provided in some other embodiments of the present application, Figure 7 for Figure 6A partial schematic diagram of an electrode assembly in the embodiment of the present application provides a battery cell 1, including an electrode assembly 10. The electrode assembly 10 is a wound structure, and the electrode assembly 10 includes a straight area 12 and a bending area 11 connected to the straight area 12. The electrode assembly 10 includes a negative electrode plate 13 and a positive electrode plate 14, the negative electrode plate 13 includes a negative electrode collector 131 and a negative electrode active material layer 132 arranged on the surface of the negative electrode collector 131, and the positive electrode plate 14 includes a positive electrode collector 141 and a positive electrode active material layer 142 arranged on the surface of the positive electrode collector 141. Among them, the negative electrode plate 13 includes a first bending section 133 located in the bending area 11, the negative electrode collector 131 includes a first main body 1311 and at least one first recess 1312, the first recess 1312 is formed on the outer surface of the first main body 1311, the negative active material layer 132 fills the first recess 1312, and the first bending section 133 is provided with at least one first recess 1312; and / or, the positive electrode plate 14 includes a second bending section 143 located in the bending area 11, the first bending section 133 and the second bending section 143 are corresponding and adjacently arranged, the second bending section 143 is located on the outside of the first bending section 133, the positive current collector 141 includes a second main body 1411 and at least one first convex portion 1412, the first convex portion 1412 protrudes from the inner surface of the second main body 1411, the positive active material layer 142 wraps the first convex portion 1412, and the second bending section 143 is provided with at least one first convex portion 1412.

[0098] In some embodiments, the electrode assembly 10 may be a wound structure, and the electrode assembly 10 may include a plurality of bending regions 11 and a plurality of straight regions 12. Along the winding direction X, one end of a bending region 11 may be connected to a straight region 12, and the other end of a bending region 11 may be connected to another straight region 12. One end of a straight region 12 may be connected to a bending region 11, and the other end of a straight region 12 may be connected to another bending region 11.

[0099] In some embodiments, the winding direction may be indicated by the direction indicated by the letter X in the figure.

[0100] In some embodiments, the electrode assembly 10 is flat. The electrode assembly 10 can be directly rolled into a flat shape, or rolled into a circular or elliptical shape and then compacted in the middle to form a flat area 12 in the middle of the electrode assembly 10 .

[0101] In some embodiments, the electrode assembly 10 includes a negative electrode plate 13 and a positive electrode plate 14 , the negative electrode plate 13 includes a negative electrode collector 131 and a negative electrode active material layer 132 disposed on the surface of the negative electrode collector 131 , and the positive electrode plate 14 includes a positive electrode collector 141 and a positive electrode active material layer 142 disposed on the surface of the positive electrode collector 141 .

[0102] Taking lithium-ion battery cell 1 as an example, the positive electrode current collector 141 may be made of aluminum, and the positive electrode active material may be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide, etc. The negative electrode current collector 131 may be made of copper, and the negative electrode active material may be carbon or silicon, etc.

[0103] In some embodiments, the electrode assembly 10 may include a positive electrode sheet 14, a negative electrode sheet 13 and a separator 15, wherein the separator 15 is used to separate the adjacent positive electrode sheets 14 and negative electrode sheets 13, and the positive electrode sheets 14, the negative electrode sheets 13 and the separator 15 are wound to form the electrode assembly 10. The winding direction X of the positive electrode sheet 14, the negative electrode sheet 13 and the separator 15 is the winding direction X of the electrode assembly 10.

[0104] In some embodiments, the material of the diaphragm 15 may be PP (polypropylene) or PE (polyethylene).

[0105] In some embodiments, the negative electrode sheet 13 includes a first bending section 133 located in the bending area 11, and the first bending section 133 is also bent. The positive electrode sheet 14 includes a second bending section 143 located in the bending area 11, and the second bending section 143 is also bent.

[0106] In some embodiments, the first bending section 133 may be located at the innermost circle of the negative electrode plate 13 , or at the outermost circle of the negative electrode plate 13 , or at the circle layer between the innermost circle and the outermost circle of the negative electrode plate 13 .

[0107] In some embodiments, the second bending section 143 may be located at the innermost circle of the positive electrode sheet 14 , or at the outermost circle of the positive electrode sheet 14 , or at the circle layer between the innermost circle and the outermost circle of the positive electrode sheet 14 .

[0108] In some embodiments, the first bending section 133 and the second bending section 143 are arranged correspondingly and adjacently, the second bending section 143 is located outside the first bending section 133, and the inner surface of the second bending section 143 is adjacent to the outer surface of the first bending section 133. The electrode assembly 10 is wound around the winding center, the inner surface of the positive electrode sheet 14 is the surface facing the winding center, and the outer surface of the positive electrode sheet 14 is the surface away from the winding center; the inner surface of the negative electrode sheet 13 is the surface facing the winding center, and the outer surface of the negative electrode sheet 13 is the surface away from the winding center.

[0109] The CB value refers to the margin of the negative electrode capacity over the positive electrode capacity in the same stage and under the same conditions, also known as N / P (Negative / Positive). The calculation formula is: CB value = negative electrode active material gram capacity × negative electrode surface density × negative electrode active material content ratio ÷ (positive electrode active material gram capacity × positive electrode surface density × positive electrode active material content ratio). On the bending area 11, the second bending section 143 is located on the outside of the first bending section 133, the inner surface of the second bending section 143 is adjacent to the outer surface of the first bending section 133, and the inner surface area of ​​the second bending section 143 is larger than the outer surface area of ​​the first bending section 133. The positive electrode active material layer 142 coated on the inner surface of the second bending section 143 is more than the negative electrode active material layer 132 coated on the outer surface of the first bending section 133, so that the CB value (Cell Balance) is smaller, so that there is a risk of lithium deposition on the first bending section 133.

[0110] Please refer to Figure 4 , Figure 6 and Figure 7 In some embodiments, the negative electrode current collector 131 includes a first main body portion 1311 and at least one first recess 1312 , the first recess 1312 is formed on the outer surface of the first main body portion 1311 , the negative electrode active material layer 132 fills the first recess 1312 , and the first bending section 133 is provided with at least one first recess 1312 .

[0111] In some embodiments, the first recess 1312 is formed on the outer surface of the first body portion 1311, the outer surface of the first body portion 1311 is the surface of the first body portion 1311 away from the winding center, the first recess 1312 is formed by the outer surface of the first body portion 1311 being recessed toward the inner surface of the first body portion 1311, and the opening of the first recess 1312 is located on the side away from the winding center of the first body portion 1311. The negative active material layer 132 is filled in the first recess 1312, so that the negative active material layer 132 in the area corresponding to the first recess 1312 is more than the negative active material layer 132 in the area corresponding to the first body portion 1311.

[0112] In some embodiments, the negative electrode current collector 131 may include a first recess 1312 , and the first recess 1312 is disposed in the first bending section 133 .

[0113] In some embodiments, the negative electrode current collector 131 may include two or more first recesses 1312 , the first bending section 133 may be provided with one or more first recesses 1312 , and the negative electrode plate 13 may also include other bending sections, which may also be provided with one or more first recesses 1312 .

[0114] At least one first recess 1312 is disposed on the first bending section 133 , thereby increasing the negative electrode active material layer 132 on the outer surface of the first bending section 133 , improving the CB value, and reducing the risk of lithium deposition in the first bending section 133 .

[0115] In some embodiments, the first bending section 133 may be provided with a first recess 1312 , and the first recess 1312 may correspond to the entire first bending section 133 , or may correspond to a partial area of ​​the first bending section 133 .

[0116] In some embodiments, the first bending section 133 may be provided with a plurality of first recesses 1312 , and the plurality of first recesses 1312 may be arranged at intervals along the winding direction X in the first bending section 133 .

[0117] Please refer to Figures 5 to 7 In some embodiments, the positive electrode current collector 141 includes a second body portion 1411 and at least one first protrusion 1412 , the first protrusion 1412 protrudes from the inner surface of the second body portion 1411 , the positive electrode active material layer 142 wraps the first protrusion 1412 , and the second bending section 143 is provided with at least one first protrusion 1412 .

[0118] In some embodiments, the first convex portion 1412 is formed on the inner surface of the second body portion 1411, the inner surface of the second body portion 1411 is the surface of the second body portion 1411 facing the winding center, the first convex portion 1412 is formed by the inner surface of the second body portion 1411 protruding away from the outer surface of the second body portion 1411, and the first convex portion 1412 protrudes from the side of the second body portion 1411 facing the winding center. The positive electrode active material layer 142 is wrapped around the first convex portion 1412, so that the positive electrode active material layer 142 in the area corresponding to the first convex portion 1412 is less than the positive electrode active material layer 142 in the area corresponding to the second body portion 1411.

[0119] In some embodiments, the positive electrode current collector 141 may include a first protrusion 1412 , and the first protrusion 1412 is disposed at the second bending section 143 .

[0120] In some embodiments, the positive electrode current collector 141 may include two or more first protrusions 1412 , the second bending section 143 may be provided with one or more first protrusions 1412 , and the positive electrode plate 14 may also include other bending sections, which may also be provided with one or more first protrusions 1412 .

[0121] At least one first protrusion 1412 is disposed on the second bending section 143 , thereby reducing the positive electrode active material layer 142 on the inner surface of the second bending section 143 , improving the CB value, and reducing the risk of lithium deposition in the first bending section 133 .

[0122] In some embodiments, the second bending section 143 may be provided with a first convex portion 1412 , and the first convex portion 1412 may correspond to the entire second bending section 143 , or may correspond to a partial area of ​​the second bending section 143 .

[0123] In some embodiments, the second bending section 143 may be provided with a plurality of first protrusions 1412 , and the plurality of first protrusions 1412 may be arranged at intervals along the winding direction X on the first bending section 133 .

[0124] In some embodiments, the electrode assembly 10 includes a positive electrode sheet 14 and a negative electrode sheet 13 , and a first recess 1312 is disposed on the outer surface of the negative electrode current collector 131 on the first bent section 133 of the negative electrode sheet 13 .

[0125] In some embodiments, the electrode assembly 10 includes a positive electrode sheet 14 and a negative electrode sheet 13 . On the second bent section 143 of the positive electrode sheet 14 , a first protrusion 1412 is disposed on the inner surface of the positive current collector 141 .

[0126] In some embodiments, the electrode assembly 10 includes a positive electrode sheet 14 and a negative electrode sheet 13, and a first concave portion 1312 is disposed on the outer surface of the negative electrode collector 131 on the first bent section 133 of the negative electrode sheet 13. Meanwhile, a first convex portion 1412 is disposed on the inner surface of the positive electrode collector 141 on the second bent section 143 of the positive electrode sheet 14.

[0127] The technical solution of the embodiment of the present application is to form a first concave portion 1312 on the outer surface of the first main body 1311 of the negative current collector 131, the negative active material layer 132 is filled in the first concave portion 1312, and the first bending portion is provided with at least one first concave portion 1312; and / or, to form a first convex portion 1412 on the inner surface of the second main body 1411 of the positive current collector 141, the positive active material layer 142 wraps the first convex portion 1412, and the second bending portion is provided with at least one first convex portion 1412. In this way, on the bending area 11, the negative active material layer 132 on the first bending portion increases and / or the positive active material layer 142 on the second bending portion decreases, thereby reducing the risk of lithium deposition on the bending area 11, improving the reliability of the battery cell 1, and improving the reliability of the battery 100.

[0128] Please refer to Figure 4 , Figure 6 and Figure 7 , and refer to Figure 8 and Fig. 9 , Figure 8 A schematic diagram of a negative electrode sheet provided in some embodiments of the present application, Fig. 9 Schematic diagram of negative electrode current collector provided in some embodiments of the present application. Figure 8 It only shows part of the negative electrode. Fig. 9Only part of the negative electrode current collector is shown schematically. In some embodiments, the negative electrode current collector 131 includes a first body portion 1311 and at least one first recess 1312, the first recess 1312 is formed on the outer surface of the first body portion 1311, the negative electrode active material layer 132 fills the first recess 1312, and the first bending section 133 is provided with at least one first recess 1312. When the negative electrode sheet 13 is unfolded, the outer surface of the area corresponding to the negative electrode active material layer 132 and the first body portion 1311 and the outer surface of the area corresponding to the negative electrode active material layer 132 and the first recess 1312 are coplanar.

[0129] In some embodiments, the negative active material layer 132 has an inner surface and an outer surface. In the thickness direction of the negative current collector 131 , the inner surface of the negative active material layer 132 is the surface facing the first body portion 1311 , and the outer surface of the negative active material layer 132 is the surface away from the first body portion 1311 .

[0130] The inner surface of the negative electrode active material layer 132 in the area corresponding to the first body portion 1311 is in contact with the surface of the area corresponding to the first body portion 1311, the inner surface of the negative electrode active material layer 132 in the area corresponding to the first recessed portion 1312 is in contact with the surface of the area corresponding to the first recessed portion 1312, and the outer surface of the negative electrode active material layer 132 in the area corresponding to the first body portion 1311 and the outer surface of the negative electrode active material layer 132 in the area corresponding to the first recessed portion 1312 are coplanar. That is, the negative electrode active material layer 132 in the area corresponding to the first recessed portion 1312 is more than the negative electrode active material layer 132 in the area corresponding to the first body portion 1311, and the number of negative electrode active material layers 132 in the area corresponding to the first recessed portion 1312 is increased, so that the CB value is increased.

[0131] According to the technical solution of the embodiment of the present application, the first recess 1312 is formed on the outer surface of the first main body 1311, the negative electrode active material layer 132 fills the first recess 1312, and the outer surface of the negative electrode active material layer 132 and the outer surface of the corresponding area of ​​the first main body 1311 and the outer surface of the negative electrode active material layer 132 and the first recess 1312 are coplanar, so that the negative electrode active material layer 132 on the outer surface of the corresponding area of ​​the first main body 1311 increases, thereby reducing the risk of lithium deposition on the bending area 11, improving the reliability of the battery cell 1, and improving the reliability of the battery 100.

[0132] Please refer to Figure 4 , Figures 6 to 9In some embodiments, the negative electrode current collector 131 includes a first body portion 1311 and at least one first recess 1312, the first recess 1312 is formed on the outer surface of the first body portion 1311, the negative electrode active material layer 132 fills the first recess 1312, and the first bending section 133 is provided with at least one first recess 1312. The thickness of the negative electrode current collector 131 at the first recess 1312 is greater than 0 and less than or equal to 0.8 times the thickness of the first body portion 1311.

[0133] The first recess 1312 is formed on the outer surface of the first main body 1311 . The thickness of the negative electrode current collector 131 at the first recess 1312 is less than the thickness of the first main body 1311 . When the negative electrode active material layer 132 fills the first recess 1312 , more negative electrode active material layers 132 can be arranged at the position corresponding to the first recess 1312 .

[0134] In some embodiments, the thickness of the negative electrode current collector 131 at the first recess 1312 may be represented by the letter d1, and the thickness of the first body portion 1311 may be represented by d2.

[0135] In some embodiments, the thickness d1 of the negative electrode current collector 131 at the first recess 1312 and the thickness d2 of the first body portion 1311 may satisfy the above conditions, and d1 may be 0.1*d2, 0.2*d2, 0.3*d2, 0.4*d2, 0.5*d2, 0.6*d2, 0.7*d2, 0.8*d2, etc.

[0136] For example, d2 can be 10 μm, and d1 can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, etc.

[0137] According to the technical solution of the embodiment of the present application, the thickness of the negative electrode current collector 131 at the first recess 1312 meets the above conditions, thereby reducing the risk of breakage of the negative electrode plate 13 during winding, and reducing the risk of lithium deposition on the bending area 11, thereby improving the reliability of the battery cell 1 and the reliability of the battery 100.

[0138] Please refer to Figure 4 , Figures 6 to 9 In some embodiments, the thickness of the negative electrode current collector 131 at the first recess 1312 is greater than 0 and less than or equal to 0.5 times the thickness of the first body portion 1311 .

[0139] In some embodiments, the thickness of the negative electrode current collector 131 at the first recess 1312 may be represented by the letter d1, and the thickness of the first body portion 1311 may be represented by d2.

[0140] In some embodiments, the thickness d1 of the negative electrode current collector 131 at the first recess 1312 and the thickness d2 of the first body portion 1311 may satisfy the above conditions, and d1 may be 0.1*d2, 0.15*d2, 0.2*d2, 0.25*d2, 0.3*d2, 0.35*d2, 0.4*d2, 0.45*d2, 0.5*d2, etc.

[0141] According to the technical solution of the embodiment of the present application, the thickness of the negative electrode current collector 131 at the first recess 1312 meets the above conditions, further reducing the risk of the negative electrode plate 13 breaking during winding, while reducing the risk of lithium deposition on the bending area 11, thereby improving the reliability of the battery cell 1 and the reliability of the battery 100.

[0142] Please refer to Figure 4 , Figure 6 and Figure 7 In some embodiments, the negative electrode current collector 131 includes a first body portion 1311 and at least one first recess 1312, the first recess 1312 is formed on the outer surface of the first body portion 1311, the negative electrode active material layer 132 fills the first recess 1312, and the first bending section 133 is provided with at least one first recess 1312. The first bending section 133 is located at the innermost circle of the negative electrode sheet 13.

[0143] In some embodiments, the negative electrode sheet 13 may include a first bending section 133 , and the first bending section 133 is located at the innermost circle of the negative electrode sheet 13 , where the innermost circle refers to a circle wound along the winding direction X starting from the starting end of the negative electrode sheet 13 .

[0144] In some embodiments, starting from the starting end of the negative electrode sheet 13 , one circle of winding along the winding direction X may form two bent portions, and one of the bent portions may be the first bent segment 133 .

[0145] In some embodiments, starting from the starting end of the negative electrode sheet 13, one circle of winding along the winding direction X can form two curved parts, both of which can be first curved sections 133, and the two first curved sections 133 are symmetrically arranged relative to the winding center.

[0146] According to the technical solution of the embodiment of the present application, the first bending section 133 is located at the innermost circle of the negative electrode plate 13 , which reduces the risk of lithium deposition in the innermost bending area 11 , improves the reliability of the battery cell 1 , and improves the reliability of the battery 100 .

[0147] Please refer to Figure 4 , Figure 6 and Figure 7In some embodiments, the negative electrode current collector 131 includes a first body portion 1311 and at least one first recess 1312, the first recess 1312 is formed on the outer surface of the first body portion 1311, the negative electrode active material layer 132 fills the first recess 1312, and the first bending section 133 is provided with at least one first recess 1312. At least a portion of the first recess 1312 is located in the first bending section 133.

[0148] The negative electrode sheet 13 may include a first straight section 134 and a second straight section 135 , which are respectively located in two adjacent straight areas 12 , and the first straight section 134 , the first bent section 133 and the second straight section 135 are arranged in sequence along the winding direction X.

[0149] In some embodiments, the first bending section 133 may be provided with a first recess 1312 , a portion of the first recess 1312 may be located in the first bending section 133 , and another portion may be located in the first straight section 134 or the second straight section 135 .

[0150] In some embodiments, the first bending section 133 may be provided with a first recessed portion 1312, and the entire portion of the first recessed portion 1312 may be located in the first bending section 133. In particular, both ends of the first recessed portion 1312 may be located in the first bending section 133, or one end of the first recessed portion 1312 may be located in the first bending section 133, and the other end may be located at the connection between the first bending portion and the first straight section 134, or one end of the first recessed portion 1312 may be located in the first bending section 133, and the other end may be located at the connection between the first bending portion and the second straight section 135.

[0151] In some embodiments, the first bending section 133 may be provided with a first recess 1312, one end of the first recess 1312 may be located at the first straight section 134, and the other end may be located at the second straight section 135, that is, a portion of the first recess 1312 is located at the first bending section 133, a portion is located at the first straight section 134, and a portion is located at the second straight section 135.

[0152] In some embodiments, the first bending section 133 may be provided with a plurality of first recesses 1312. In particular, along the winding direction X, the plurality of first recesses 1312 may be arranged at intervals. One end of a first recess 1312 may be located at the first straight section 134, and the other end may be located at the first bending section 133. One end of another first recess 1312 may be arranged at the first bending section 133, and the other end may be arranged at the second straight section 135. Both ends of another first recess 1312 may be arranged at the first bending section 133.

[0153] According to the technical solution of the embodiment of the present application, at least a portion of the first recess 1312 is located in the first bending section 133 , which reduces the risk of lithium deposition in the first bending section 133 corresponding to the first recess 1312 , improves the reliability of the battery cell 1 , and improves the reliability of the battery 100 .

[0154] In some embodiments, the negative electrode plate 13 includes a first straight section 134 and a second straight section 135 located in the straight area 12. The first straight section 134, the first bent section 133 and the second straight section 135 are arranged in sequence along the winding direction X. Along the winding direction X, one end of the first recess 1312 is located in the first straight section 134, and the other end of the first recess 1312 is located in the second straight section 135.

[0155] In some embodiments, the electrode assembly 10 is flat, the negative electrode sheet 13 in the bending area 11 has an arc-shaped surface, and the negative electrode sheet 13 in the straight area 12 has a straight surface. Along the winding direction X, one end of the bending area 11 is connected to one straight area 12, and the other end is connected to another straight area 12. The first bending section 133 can be located in the bending area 11, the first straight section 134 can be located in one straight area 12, and the second straight section 135 can be located in another straight area 12.

[0156] In some embodiments, the first straight section 134 and the second straight section 135 may be symmetrically arranged with respect to the winding center.

[0157] In some embodiments, the number of the first recess 1312 may be one. Along the winding direction X, one end of the first recess 1312 may be located at the first straight section 134, and the other end may be located at the second straight section 135, that is, a portion of the first recess 1312 is located at the first bending section 133, a portion is located at the first straight section 134, and a portion is located at the second straight section 135.

[0158] According to the technical solution of the embodiment of the present application, the first recess 1312 exists in all parts of the first bending section 133 , which reduces the risk of lithium deposition in the first bending section 133 , improves the reliability of the battery cell 1 , and improves the reliability of the battery 100 .

[0159] Please refer to Figure 6 to Figure 7 In some embodiments, the positive electrode current collector 141 includes a second body portion 1411 and at least one first protrusion 1412, the first protrusion 1412 protrudes from the inner surface of the second body portion 1411, the positive electrode active material layer 142 wraps the first protrusion 1412, and the second bending section 143 is provided with at least one first protrusion 1412. When the positive electrode sheet 14 is unfolded, the inner surface of the area corresponding to the positive electrode active material layer 142 and the second body portion 1411 and the inner surface of the area corresponding to the positive electrode active material layer 142 and the first protrusion 1412 are coplanar.

[0160] In some embodiments, the positive active material layer 142 has an inner surface and an outer surface. In the thickness direction of the positive current collector 141, the inner surface of the positive active material layer 142 is the surface facing the winding center, and the outer surface of the positive active material layer 142 is the surface away from the winding center.

[0161] The inner surface of the positive electrode active material layer 142 in the area corresponding to the second body part 1411 is in contact with the surface of the area corresponding to the second body part 1411, the inner surface of the positive electrode active material layer 142 in the area corresponding to the first protrusion 1412 is in contact with the surface of the area corresponding to the first protrusion 1412, and the outer surface of the positive electrode active material layer 142 in the area corresponding to the second body part 1411 is coplanar with the outer surface of the positive electrode active material layer 142 in the area corresponding to the first protrusion 1412. That is, the positive electrode active material layer 142 in the area corresponding to the first protrusion 1412 is less than the positive electrode active material layer 142 in the area corresponding to the second body part 1411, and the positive electrode active material layer 142 in the area corresponding to the first protrusion 1412 is reduced, so that the CB value increases.

[0162] According to the technical solution of the embodiment of the present application, the first protrusion 1412 is formed on the inner surface of the second main body 1411, the positive electrode active material layer 142 wraps the first protrusion 1412, and the inner surface of the area corresponding to the positive electrode active material layer 142 and the second main body 1411 and the inner surface of the area corresponding to the positive electrode active material layer 142 and the first protrusion 1412 are coplanar, so that the positive electrode active material layer 142 on the inner surface of the area corresponding to the second main body 1411 is reduced, thereby reducing the risk of lithium deposition on the bending area 11, improving the reliability of the battery cell 1, and improving the reliability of the battery 100.

[0163] Please refer to Figures 5 to 7 , and refer to Fig.10 and Fig.11 , Fig.10 A schematic diagram of a negative electrode sheet provided in some embodiments of the present application, Fig.11 Schematic diagram of negative electrode current collector provided in some embodiments of the present application. Fig.10 Only part of the negative electrode is shown. Fig.11 Only a part of the negative electrode current collector is shown schematically. In some embodiments, the positive electrode current collector 141 includes a second body portion 1411 and at least one first protrusion 1412, the first protrusion 1412 protrudes from the inner surface of the second body portion 1411, the positive electrode active material layer 142 wraps the first protrusion 1412, and the second bending section 143 is provided with at least one first protrusion 1412. The thickness of the positive electrode current collector 141 at the first protrusion 1412 is greater than the thickness of the second body portion 1411, and is less than or equal to 6 times the thickness of the second body portion 1411.

[0164] In some embodiments, the thickness of the positive electrode current collector 141 at the first protrusion 1412 may be represented by letter d3, and the thickness of the second body portion 1411 may be represented by letter d4.

[0165] In some embodiments, the thickness d3 of the positive current collector 141 at the first recess 1312 and the thickness d4 of the second body portion 1411 may satisfy the above conditions, and d3 may be 1.1*d4, 2*d4, 3*d4, 4*d4, 5*d4, 6*d4, etc.

[0166] For example, d4 can be 10 μm, and d3 can be 11 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, etc.

[0167] According to the technical solution of the embodiment of the present application, the thickness of the positive electrode current collector 141 at the first protrusion 1412 meets the above conditions, which reduces the risk of breakage of the positive electrode plate 14 during winding, and reduces the risk of lithium deposition on the bending area 11, thereby improving the reliability of the battery cell 1 and the reliability of the battery 100.

[0168] Please refer to Figures 5 to 7 , and refer to Fig.10 and Fig.11 In some embodiments, the thickness of the positive electrode current collector 141 at the first protrusion 1412 is greater than the thickness of the second body portion 1411 , and less than or equal to 3 times the thickness of the second body portion 1411 .

[0169] In some embodiments, the thickness of the positive electrode current collector 141 at the first protrusion 1412 may be represented by letter d3, and the thickness of the second body portion 1411 may be represented by letter d4.

[0170] In some embodiments, the thickness d3 of the positive electrode current collector 141 at the first recess 1312 and the thickness d4 of the second body portion 1411 may meet the above conditions, and d3 may be 1.1*d4, 1.5*d4, 2*d4, 2.5*d4, 3*d4, etc.

[0171] For example, d4 can be 10 μm, and d3 can be 11 μm, 15 μm, 20 μm, 25 μm, 30 μm, etc.

[0172] According to the technical solution of the embodiment of the present application, the thickness of the positive electrode current collector 141 at the first protrusion 1412 meets the above conditions, further reducing the risk of breakage of the positive electrode plate 14 during winding, while reducing the risk of lithium deposition on the bending area 11, thereby improving the reliability of the battery cell 1 and the reliability of the battery 100.

[0173] Please refer to Figures 5 to 7In some embodiments, the positive electrode current collector 141 includes a second body portion 1411 and at least one first protrusion 1412, the first protrusion 1412 protrudes from the inner surface of the second body portion 1411, the positive electrode active material layer 142 wraps the first protrusion 1412, and the second bending section 143 is provided with at least one first protrusion 1412. The second bending section 143 is located at the innermost circle of the positive electrode sheet 14.

[0174] In some embodiments, the positive electrode sheet 14 may include a second bending section 143 , and the second bending section 143 is located at the innermost circle of the positive electrode sheet 14 , where the innermost circle refers to a circle wound along the winding direction X starting from the starting end of the positive electrode sheet 14 .

[0175] In some embodiments, starting from the starting end of the positive electrode sheet 14 , one circle of winding along the winding direction X may form two bent portions, one of which may be the second bent section 143 .

[0176] In some embodiments, starting from the starting end of the positive electrode sheet 14, one circle of winding along the winding direction X can form two curved parts, both of which can be second bending sections 143, and the two second bending sections 143 are symmetrically arranged relative to the winding center.

[0177] In the technical solution of the embodiment of the present application, the second bending section 143 is located at the innermost circle of the positive electrode plate 14 , which reduces the risk of lithium deposition in the innermost bending area 11 , improves the reliability of the battery cell 1 , and improves the reliability of the battery 100 .

[0178] Please refer to Figures 5 to 7 , and refer to Fig.10 and Fig.11 In some embodiments, the positive electrode current collector 141 includes a second body portion 1411 and at least one first protrusion 1412, the first protrusion 1412 protrudes from the inner surface of the second body portion 1411, the positive electrode active material layer 142 wraps the first protrusion 1412, and the second bending section 143 is provided with at least one first protrusion 1412. At least a portion of the first protrusion 1412 is located in the second bending section 143.

[0179] Similar to the negative electrode sheet 13, the positive electrode sheet 14 may include a third straight section 144 and a fourth straight section 145, which are respectively located in two adjacent straight areas 12, and the third straight section 144, the second bent section 143 and the fourth straight section 145 are arranged in sequence along the winding direction X.

[0180] In some embodiments, the second bending section 143 may be provided with a first convex portion 1412 , a portion of the first convex portion 1412 may be located in the second bending section 143 , and another portion may be located in the third straight section 144 or the fourth straight section 145 .

[0181] In some embodiments, the second bending section 143 may be provided with a first convex portion 1412, and the entire portion of the first convex portion 1412 may be located at the second bending section 143. In particular, both ends of the first convex portion 1412 may be located at the second bending section 143, or one end of the first convex portion 1412 may be located at the second bending section 143, and the other end may be located at the connection between the second bending portion and the third straight section 144, or one end of the first convex portion 1412 may be located at the second bending section 143, and the other end may be located at the connection between the second bending portion and the fourth straight section 145.

[0182] In some embodiments, the second bending section 143 may be provided with a first protrusion 1412, one end of the first protrusion 1412 may be located at the third straight section 144, and the other end may be located at the fourth straight section 145, that is, a portion of the first protrusion 1412 is located at the second bending section 143, a portion is located at the third straight section 144, and a portion is located at the fourth straight section 145.

[0183] In some embodiments, the second bending section 143 may be provided with a plurality of first convex portions 1412. In particular, along the winding direction X, the plurality of first convex portions 1412 may be arranged at intervals. One end of a first convex portion 1412 may be located at the third straight section 144, and the other end may be located at the second bending section 143. One end of another first convex portion 1412 may be arranged at the second bending section 143, and the other end may be arranged at the fourth straight section 145. Both ends of another first convex portion 1412 may be arranged at the second bending section 143.

[0184] According to the technical solution of the embodiment of the present application, at least a portion of the first protrusion 1412 is located at the second bending section 143 , which reduces the risk of lithium deposition in the second bending section 143 corresponding to the first protrusion 1412 , improves the reliability of the battery cell 1 , and improves the reliability of the battery 100 .

[0185] In some embodiments, the positive electrode plate 14 includes a third straight section 144 and a fourth straight section 145 located in the straight area 12. The third straight section 144, the second bent section 143 and the fourth straight section 145 are arranged in sequence along the winding direction X. Along the winding direction X, one end of the first protrusion 1412 is located in the third straight section 144, and the other end of the first protrusion 1412 is located in the fourth straight section 145.

[0186] In some embodiments, the electrode assembly 10 is flat, the positive electrode sheet 14 located in the bending area 11 has an arc-shaped surface, and the positive electrode sheet 14 located in the straight area 12 has a straight surface. Along the winding direction X, one end of the bending area 11 is connected to one straight area 12, and the other end is connected to another straight area 12. The second bending section 143 can be located in the bending area 11, the third straight section 144 can be located in one straight area 12, and the fourth straight section 145 can be located in another straight area 12.

[0187] In some embodiments, the third straight section 144 and the fourth straight section 145 may be symmetrically arranged with respect to the winding center.

[0188] In some embodiments, the number of the first convex portion 1412 may be one. Along the winding direction X, one end of the first convex portion 1412 may be located at the third straight section 144, and the other end may be located at the fourth straight section 145, that is, a portion of the first convex portion 1412 is located at the second bending section 143, a portion is located at the third straight section 144, and a portion is located at the fourth straight section 145.

[0189] According to the technical solution of the embodiment of the present application, the first convex portion 1412 is present in all parts of the second bending section 143 , thereby reducing the risk of lithium deposition in the second bending section 143 , improving the reliability of the battery cell 1 , and improving the reliability of the battery 100 .

[0190] Please refer to Fig.12 , Fig.12 Partial schematic diagram of electrode assembly provided for other embodiments of the present application. In some embodiments, along the winding direction X, the first concave portion 1312 has a first end 1313 and a second end 1314, and the first convex portion 1412 has a third end 1413 and a fourth end 1414. In the winding direction X, the first end 1313 exceeds the third end 1413. In the opposite direction of the winding direction X, the fourth end 1414 exceeds the second end 1314.

[0191] In some embodiments, the first bending segment 133 and the second bending segment 143 are arranged correspondingly and adjacently, a portion of the first concave portion 1312 may correspond to the first convex portion 1412 , and another portion may correspond to the second body portion 1411 .

[0192] In some embodiments, the position of the first end 1313 can correspond to the position of the third end 1413, and in the opposite direction of the winding direction X, the fourth end 1414 can exceed the second end 1314, so that in the radial direction of the electrode assembly, the projection of the first recess 1312 covers the projection of the first protrusion 1412.

[0193] In some embodiments, the position of the fourth end 1414 can correspond to the position of the second end 1314, and in the winding direction X, the first end 1313 exceeds the third end 1413, so that in the radial direction of the electrode assembly, the projection of the first recess 1312 covers the projection of the first protrusion 1412.

[0194] According to the technical solution of the embodiment of the present application, in the winding direction X, the first end 1313 exceeds the third end 1413. In the opposite direction of the winding direction X, the fourth end 1414 exceeds the second end 1314, so that the first convex portion 1412 corresponds to at least a portion of the first concave portion 1312, reducing the risk of lithium deposition in the first bending section 133, improving the reliability of the battery cell 1, and improving the reliability of the battery 100.

[0195] The embodiment of the present application further provides a battery 100 , comprising the battery cell 1 of any one of the above embodiments.

[0196] An embodiment of the present application further provides an electrical device, comprising a battery cell 1 of any of the above embodiments or a battery 100 of any of the above embodiments, wherein the battery cell 1 or the battery 100 is used to provide electrical energy.

[0197] Please refer to Figures 4 to 11 In some embodiments, the battery cell 1 includes a wound electrode assembly 10. The electrode assembly 10 includes a negative electrode sheet 13 and a positive electrode sheet 14. The negative electrode sheet 13 includes a negative current collector 131 and a negative active material layer 132 disposed on the surface of the negative current collector 131. The positive electrode sheet 14 includes a positive current collector 141 and a positive active material layer 142 disposed on the surface of the positive current collector 141.

[0198] The negative electrode sheet 13 includes a first bending section 133 located in the bending area 11 , and the positive electrode sheet 14 includes a second bending section 143 located in the bending area 11 . The first bending section 133 and the second bending section 143 are arranged correspondingly and adjacently, and the second bending section 143 is located outside the first bending section 133 .

[0199] The negative electrode current collector 131 includes a first body portion 1311 and at least one first recess 1312, the first recess 1312 is formed on the outer surface of the first body portion 1311, the negative electrode active material layer 132 fills the first recess 1312, and the first bending section 133 is provided with at least one first recess 1312. The positive electrode current collector 141 includes a second body portion 1411 and at least one first protrusion 1412, the first protrusion 1412 protrudes from the inner surface of the second body portion 1411, the positive electrode active material layer 142 wraps the first protrusion 1412, and the second bending section 143 is provided with at least one first protrusion 1412.

[0200] In some embodiments, the first bending section 133 and the second bending section 143 are arranged correspondingly and adjacently, and the first concave portion 1312 and the first convex portion 1412 can be arranged correspondingly. In the radial direction of the electrode assembly, the projection of the first concave portion 1312 overlaps with the projection of the first convex portion 1412.

[0201] The technical solution of the embodiment of the present application is to set a first recess 1312 in the first bending section 133 and a first protrusion 1412 in the second bending section 143, thereby increasing the negative electrode active material layer 132 and reducing the positive electrode active material layer 142, thereby reducing the risk of lithium deposition on the bending area 11, improving the reliability of the battery cell 1, and improving the reliability of the battery 100.

[0202] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that: include: The electrode assembly is a wound structure, and the electrode assembly includes a straight area and a bending area connected to the straight area; The electrode assembly comprises a negative electrode sheet and a positive electrode sheet, wherein the negative electrode sheet comprises a negative electrode current collector and a negative electrode active material layer disposed on the surface of the negative electrode current collector, and the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer disposed on the surface of the positive electrode current collector; Wherein, the negative electrode plate includes a first bending section located in the bending area, the negative electrode current collector includes a first main body and at least one first recess, the first recess is formed on the outer surface of the first main body, the negative electrode active material layer fills the first recess, and the first bending section is provided with at least one first recess; and / or, The positive electrode sheet includes a second bending section located in the bending area, the first bending section and the second bending section are corresponding and adjacent to each other, the second bending section is located on the outside of the first bending section, the positive electrode collector includes a second main body and at least one first convex portion, the first convex portion protrudes from the inner surface of the second main body, the positive electrode active material layer wraps the first convex portion, and the second bending section is provided with at least one first convex portion.

2. The battery cell according to claim 1, characterized in that: When the negative electrode sheet is unfolded, an outer surface of a region where the negative electrode active material layer corresponds to the first main body portion and an outer surface of a region where the negative electrode active material layer corresponds to the first recessed portion are coplanar.

3. The battery cell according to claim 1, characterized in that: The thickness of the negative electrode current collector at the first recess is greater than 0 and less than or equal to 0.8 times the thickness of the first body portion.

4. The battery cell according to claim 3, characterized in that: The thickness of the negative electrode current collector at the first recess is greater than 0 and less than or equal to 0.5 times the thickness of the first body portion.

5. The battery cell according to claim 1, characterized in that: The first bending section is located at the innermost circle of the negative electrode plate.

6. The battery cell according to claim 1, characterized in that: At least a portion of the first recess is located in the first bending section.

7. The battery cell according to claim 6, characterized in that: The negative electrode plate includes a first straight section and a second straight section located in the straight area, the first straight section, the first bent section and the second straight section are arranged in sequence along the winding direction, and along the winding direction, one end of the first recess is located in the first straight section, and the other end of the first recess is located in the second straight section.

8. The battery cell according to claim 1, characterized in that: When the positive electrode sheet is unfolded, the inner surface of the region corresponding to the positive electrode active material layer and the second body portion is coplanar with the inner surface of the region corresponding to the positive electrode active material layer and the first protrusion portion.

9. The battery cell according to claim 1, characterized in that: The thickness of the positive electrode current collector at the first protrusion is greater than the thickness of the second body portion, and is less than or equal to 6 times the thickness of the second body portion.

10. The battery cell according to claim 9, characterized in that: The thickness of the positive electrode current collector at the first protrusion is greater than the thickness of the second body portion and less than or equal to 3 times the thickness of the second body portion.

11. The battery cell according to claim 1, characterized in that: The second bending section is located at the innermost circle of the positive electrode plate.

12. The battery cell according to claim 1, characterized in that: At least a portion of the first protrusion is located in the second bending section.

13. The battery cell according to claim 12, characterized in that: The positive electrode plate includes a third straight section and a fourth straight section located in the straight area. The third straight section, the second bent section and the fourth straight section are arranged in sequence along the winding direction. Along the winding direction, one end of the first protrusion is located in the third straight section, and the other end of the first protrusion is located in the fourth straight section.

14. The battery cell according to claim 1, characterized in that: Along the winding direction, the first concave portion has a first end and a second end, and the first convex portion has a third end and a fourth end; In the winding direction, the first end exceeds the third end, and in the opposite direction to the winding direction, the fourth end exceeds the second end.

15. A battery, characterized in that: include: A battery cell as claimed in any one of claims 1 to 14.

16. An electrical equipment, characterized in that: The invention comprises the battery cell according to any one of claims 1 to 14 or the battery according to claim 15, wherein the battery cell or the battery is used to provide electrical energy to the electrical device.

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