Battery monomer, battery device and electric device

Abstract

The utility model provides a battery monomer, a battery device and a power utilization device, the battery monomer comprises a shell and an electrode assembly accommodated in the shell, the electrode assembly comprises a first pole piece and a second pole piece which are opposite in polarity, and the first pole piece and the second pole piece are arranged in a winding manner. The first pole piece comprises a first current collector and a first film layer arranged on the surface of the first current collector, the first current collector comprises a first current collecting part and a second current collecting part which are arranged in the winding direction, and the thickness of the second current collecting part is larger than that of the first current collecting part. The reliability of the battery monomer can be improved.

Description

Technical Field

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

[0002] Battery cells are widely used in electronic devices, such as mobile phones, laptop computers, battery-powered vehicles, electric vehicles, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools, etc. Battery cells can include nickel-cadmium battery cells, nickel-metal hydride battery cells, lithium-ion battery cells, and secondary alkaline zinc-manganese battery cells, etc.

[0003] In the development of battery technology, how to improve the reliability of batteries has always been a research direction in battery technology. Summary of the Utility Model

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

[0005] In a first aspect, the present application provides a battery cell. The battery cell includes a housing and an electrode assembly accommodated in the housing. The electrode assembly includes a first pole piece and a second pole piece with opposite polarities, and the first pole piece and the second pole piece are wound. The first pole piece includes a first current collector and a first film layer provided on the surface of the first current collector. The first current collector includes a first current collecting portion and a second current collecting portion arranged along the winding direction, and the thickness of the second current collecting portion is greater than that of the first current collecting portion.

[0006] In the above solution, by providing the first current collecting portion, the manufacturing cost can be reduced, the overall thickness of the electrode assembly can be reduced, and thus the group margin of the battery cell can be reduced. By providing the first current collecting portion and the second current collecting portion, and the thickness of the second current collecting portion is greater than that of the first current collecting portion, the tensile strength of the pole piece located in the outer ring of the electrode assembly can be improved, thereby reducing the risk of pole piece fracture caused by expansion during the operation of the battery cell and improving the reliability of the battery cell.

[0007] In some embodiments, the electrode assembly has a flat region and a bent region, and the connection between the first current collecting portion and the second current collecting portion is located in the bent region.

[0008] In the above solution, the connection between the first current collecting portion and the second current collecting portion can be understood as the junction between the first current collecting portion and the second current collecting portion. Since the electrode assembly in the bent region needs to be bent, the electrode assembly has a curved edge in the bent region, and the distance between the curved edge and the housing is greater than the distance between the electrode assembly in the flat region and the housing. Arranging the connection in the bent region is beneficial to reducing the possibility of non-uniform thickness of the electrode assembly in the flat region, and thus reducing the possibility of interference between the electrode assembly in the flat region and the housing of the battery cell.

[0009] In some embodiments, the first current collector includes a first head end and a first tail end that are opposite to each other in the winding direction, the second current collector includes a second head end and a second tail end that are opposite to each other in the winding direction, and the second head end is connected to the first tail end. The first head end is the starting end of the winding of the first current collector, and the second tail end is the ending end of the winding of the first current collector.

[0010] In the above solution, the first current collector is a continuous structure, thereby improving the winding efficiency.

[0011] In some embodiments, the second current collector winds at least one turn, which is beneficial to improving the overall strength of the first current collector while reducing the manufacturing cost of the first electrode tab.

[0012] In some embodiments, the second current collector includes a single-side section, and the outer surface of the single-side section is not provided with a first film layer. The single-side section includes the second tail end.

[0013] In the above solution, by providing the single-side section, it is beneficial to reduce the influence of the first film layer on the tensile strength of the first current collector and improve the tensile strength of the second current collector. For example, when the first electrode tab is a negative electrode tab, the first film layer includes graphite slurry, and the graphite slurry causes the tensile strength of the second current collector to decrease. The tensile strength of the single-side section is greater than that of the first current collector, thereby improving the overall tensile strength of the first electrode tab, further reducing the possibility of the electrode tab in the electrode assembly breaking, and improving the reliability of the battery cell.

[0014] In some embodiments, the tensile strength of the second current collector is greater than that of the first current collector to reduce the possibility of the second current collector breaking due to the expansion force and further improve the reliability of the battery cell.

[0015] In some embodiments, the first current collector and the second current collector are connected by an adhesive layer. The adhesive layer includes a conductive material to reduce the connection difficulty between the first current collector and the second current collector and reduce the resistance between the first current collector and the second current collector.

[0016] In some embodiments, the first current collector and the second current collector overlap in the thickness direction to form an overlapping area. The adhesive layer is disposed in the overlapping area and is located between the first current collector and the second current collector.

[0017] In the above solution, by providing the overlapping area and disposing the adhesive layer in the overlapping area, it is beneficial to increase the bonding area between the first current collector and the second current collector and the adhesive layer, thereby reducing the possibility of the first current collector and the second current collector separating.

[0018] In some embodiments, the size of the overlapping area in the winding direction is ≥3 mm to increase the bonding area between the first current collector and the second current collector and the adhesive layer and reduce the possibility of the first current collector and the second current collector separating.

[0019] In some embodiments, the side walls of the first current collector portion and the second current collector portion are in abutting contact, and adhesive layers are provided on at least one side of the first current collector portion and the second current collector portion in the thickness direction.

[0020] In the above solution, it is beneficial to reduce the overall thickness at the connection between the first current collector portion and the second current collector portion, thereby reducing the possibility of interference between the electrode assembly and the housing caused by the outward protrusion at the connection between the first current collector portion and the second current collector portion, and improving the energy density of the battery cell.

[0021] In some embodiments, the first current collector portion includes a first non-coated area, the second current collector portion includes a second non-coated area, the first film layer is not provided in both the first non-coated area and the second non-coated area, and both the first non-coated area and the second non-coated area are connected to the adhesive layer.

[0022] In the above solution, it is beneficial to shorten the conductive distance between the first current collector portion and the second current collector portion, such that the adhesive layer, the first film layer, and the second film layer share the space in the thickness direction, so as to reduce the overall thickness of the first electrode sheet, thereby reducing the overall thickness of the electrode assembly and improving the energy density of the battery cell.

[0023] In some embodiments, the second current collector portion includes a first stacked portion and a second stacked portion which are stacked, and the first stacked portion and the first current collector portion are an integral structure.

[0024] In the above solution, by providing the first stacked portion and the second stacked portion, it is beneficial to reduce the possibility of separation between the first current collector portion and the second current collector portion while improving the flexibility of the arrangement of the second current collector portion.

[0025] In some embodiments, the thickness of the second current collector portion is greater than or equal to 6 μm to further improve the tensile strength of the second current collector portion and reduce the possibility of the second current collector portion breaking under the action of the swelling force.

[0026] In a second aspect, an embodiment of the present application provides a battery cell, which includes a housing and the electrode assembly in any of the foregoing embodiments.

[0027] In a third aspect, an embodiment of the present application provides a battery device, which includes the battery cell in any of the foregoing embodiments.

[0028] In a fourth aspect, an embodiment of the present application provides an electrical device, which includes the battery device in any of the foregoing embodiments, and the battery device is used to provide electrical energy.

[0029] The above description is only an overview of the technical solution of the present application. In order to be able to understand the technical means of the present application more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features, and advantages of the present application more obvious and understandable, the specific embodiments of the present application are specifically described below. Brief Description of the Drawings

[0030] To more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0031] Figure 1 is a schematic structural diagram of a vehicle provided by an embodiment of the present application;

[0032] Figure 2 is an exploded structural diagram of a battery device provided by an embodiment of the present application;

[0033] Figure 3 is a schematic structural diagram of a battery module provided by an embodiment of the present application;

[0034] Figure 4 is an exploded structural diagram of a battery cell provided by an embodiment of the present application;

[0035] Figure 5 is a schematic diagram of an electrode assembly provided by an embodiment of the present application;

[0036] Figure 6 is another schematic structural diagram of an electrode assembly provided by an embodiment of the present application;

[0037] Figure 7 is another schematic structural diagram of an electrode assembly provided by an embodiment of the present application;

[0038] Figure 8 is a schematic diagram of the connection between the first current collector part and the second current collector part in the first electrode tab of an electrode assembly provided by an embodiment of the present application;

[0039] Figure 9 is another schematic diagram of the connection between the first current collector part and the second current collector part in the first electrode tab of an electrode assembly provided by an embodiment of the present application;

[0040] Figure 10 is another schematic diagram of the connection between the first current collector part and the second current collector part in the first electrode tab of an electrode assembly provided by an embodiment of the present application;

[0041] Figure 11 is another schematic diagram of the connection between the first current collector part and the second current collector part in the first electrode tab of an electrode assembly provided by an embodiment of the present application;

[0042] Figure 12 is another schematic diagram of the connection between the first current collector part and the second current collector part in the first electrode tab of an electrode assembly provided by an embodiment of the present application.

[0043] Marking Explanation

[0044] 1000, Vehicle;

[0045] 100, Battery device; 200, Controller; 300, Motor; 400, Box; 410, First box part; 420, Second box part; 430, Accommodating part; 500, Battery module;

[0046] 110, Battery cell; 101, Outer casing; 102, Electrode assembly;

[0047] 10, First pole piece; 11, First current collector; 111, First current collecting part; 111a, First leading end; 111b, First trailing end; 112, Second current collecting part; 112a, Second leading end; 112b, Second trailing end; 113, Unilateral section; 112c, First stacked part; 112d, Second stacked part; 12, First film layer;

[0048] 20, Second pole piece; 21, Second current collector; 22, Second film layer;

[0049] 30, Adhesive layer; SE, Winding start end; CE, Winding end; FA, Straight area; BA, Bending area; V, Winding direction. Detailed Embodiment

[0050] Hereinafter, embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, so they are only examples and cannot be used to limit the protection scope of the present application.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above accompanying drawings are intended to cover non-exclusive inclusion.

[0052] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present application, "a plurality" means more than two unless otherwise specifically defined.

[0053] References to "embodiments" in this specification mean that the specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment each time, nor are they independent or alternative embodiments mutually exclusive of other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0054] In the description of the embodiments of the present application, the term "and / or" is merely a relationship describing the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Additionally, the character " / " in this text generally represents an "or" relationship between the associated objects before and after.

[0055] In the description of the embodiments of the present application, the term "plurality" refers to two or more (including two). Similarly, "multiple groups" refers to two or more groups (including two groups), and "multiple pieces" refers to two or more pieces (including two pieces).

[0056] In the description of the embodiments of the present application, the orientation or positional relationships indicated by technical terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. are based on the orientation or positional relationships shown in the drawings. This is only for the convenience of describing the embodiments of the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the embodiments of the present application.

[0057] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "coupling", "fixing", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0058] In the embodiments of the present application, the battery cell can be a secondary battery, which refers to a battery cell that can be activated by charging after discharging and can continue to be used.

[0059] The battery cell can be a lithium-ion battery, a sodium-ion battery, a sodium-lithium-ion battery, a lithium metal battery, a sodium metal battery, a lithium-sulfur battery, a magnesium-ion battery, a nickel-metal hydride battery, a nickel-cadmium battery, a lead-acid battery, etc., and the embodiments of the present application are not limited thereto.

[0060] The 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 inserted and extracted back and forth between the positive electrode and the negative electrode. The separator is disposed between the positive electrode and the negative electrode, which can prevent the short circuit between the positive and negative electrodes and allow the active ions to pass through at the same time.

[0061] In some embodiments, the positive electrode can be a positive electrode sheet, and the positive electrode sheet can include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0062] As an example, the positive electrode current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode active material is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0063] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium with silver surface treatment can be used. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0064] In some embodiments, the negative electrode can be a negative electrode sheet, and the negative electrode sheet can include a negative electrode current collector.

[0065] As an example, the negative electrode current collector can be a metal foil, a foam metal, a foam carbon or a composite current collector. For example, as the metal foil, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium with silver surface treatment can be used. The foam metal can be foam nickel, foam copper, foam aluminum or foam alloy, etc. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0066] As an example, the negative electrode sheet can include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0067] As an example, the negative electrode current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode active material is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0068] As an example, the negative electrode active material can be the negative electrode active material for a battery cell known in the art. As an example, the negative electrode active material can include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc.

[0069] In some embodiments, the material of the positive electrode current collector can be aluminum, and the material of the negative electrode current collector can be copper.

[0070] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0071] In some embodiments, the separator is a separator membrane. The present application does not particularly limit the type of the separator membrane, and any known porous structure separator membrane with good chemical stability and mechanical stability can be selected.

[0072] As an example, the main material of the separator membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic.

[0073] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive electrode and the negative electrode, and simultaneously functions to transport ions and isolate the positive and negative electrodes.

[0074] In some embodiments, the battery cell further includes an electrolyte, and the electrolyte functions to conduct ions between the positive and negative electrodes. The present application does not specifically limit the type of the electrolyte, and it can be selected according to requirements. The electrolyte can be liquid, gel-like, or solid.

[0075] In some embodiments, the electrode assembly is provided with tabs, and the tabs can lead out the current from the electrode assembly. The tabs include a positive tab and a negative tab.

[0076] The battery device mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.

[0077] In some embodiments, the battery device can be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0078] In some embodiments, the battery device can be a battery pack, and the battery pack includes a box body and battery cells, and the battery cells or battery modules are accommodated in the box body.

[0079] In some embodiments, the box body can be part of the chassis structure of a vehicle. For example, a part of the box body can become at least part of the floor of the vehicle, or a part of the box body can become at least part of the cross beams and longitudinal beams of the vehicle.

[0080] In some embodiments, the battery device can be an energy storage device. The energy storage device includes an energy storage container, an energy storage electric cabinet, etc.

[0081] The development of battery technology needs to consider various design factors simultaneously. For example, performance parameters such as energy density, cycle life, discharge capacity, charge-discharge rate, etc. In addition, the reliability of the battery cell also needs to be considered.

[0082] During the cycling process, the electrode assembly expands. During the expansion process, the outer pole pieces are prone to breakage under the action of the expansion force of the inner pole pieces, resulting in a decrease in the service life of the battery cell.

[0083] Based on the above technical problems, the present application provides a technical solution. The thickness of the second current collector part is greater than that of the first current collector part, so that the tensile strength of the second current collector part is greater than that of the first current collector part, thereby reducing the influence of the expansion force generated by the first current collector part during the cycling of the battery core on the second current collector part, and further reducing the possibility of the second current collector part breaking, and improving the reliability of the battery cell.

[0084] The technical solutions described in the embodiments of the present application are applicable to battery devices and electrical devices using battery devices. The electrical devices are, for example, mobile phones, portable devices, laptop computers, battery cars, electric vehicles, ships, spacecrafts, electric toys, and electric tools, etc. Among them, the spacecrafts are, for example, airplanes, rockets, space shuttles, and spaceships, etc. The electric toys include, for example, fixed or mobile electric toys. Specifically, for example, game consoles, electric vehicle toys, electric ship toys, and electric airplane toys, etc. The electric tools include, for example, metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools. Specifically, for example, electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact electric drills, concrete vibrators, and electric planers.

[0085] The battery cells described in the embodiments of the present application are not limited to the above-described electrical devices. However, for the sake of simplicity of description, the following embodiments will be described by taking electric vehicles as examples.

[0086] Please refer to Figure 1 , Figure 1It is a schematic structural diagram of a vehicle provided by an embodiment of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle, or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle, an extended-range vehicle, etc. A battery device 100 can be arranged inside the vehicle 1000. Specifically, for example, the battery device 100 can be arranged at the bottom, the front end, or the rear end of the vehicle 1000. The battery device 100 can be used to supply power to the vehicle 1000. For example, the battery device 100 can be used as the operating power source of the vehicle 1000. The vehicle 1000 can also include a controller 200 and a motor 300. The controller 200 is used to control, for example, the power supply of the battery device to the motor 300. The battery device can be used for starting, navigation, etc. of the vehicle 1000. Of course, the battery device 100 can also be used to drive the vehicle 1000 to travel, replacing or partially replacing fuel or natural gas to provide drive for the vehicle 1000.

[0087] Figure 2 It is an exploded structural schematic diagram of a battery device provided by an embodiment of the present application. As Figure 2 shown, the battery device 100 includes a box body 400 and battery cells (not shown in the figure). The battery cells are accommodated in the box body 400.

[0088] The box body 400 is used to accommodate the battery cells, and the box body 400 can have various structures. In some embodiments, the box body 400 can include a first box body part 410 and a second box body part 420. The first box body part 410 and the second box body part 420 cover each other, and the first box body part 410 and the second box body part 420 jointly define a receiving part 430 for accommodating the battery cells. The second box body part 420 can be a hollow structure with one end open, and the first box body part 410 is a plate-like structure. The first box body part 410 covers the open side of the second box body part 420 to form a box body with the receiving part 430; both the first box body part 410 and the second box body part 420 can also be hollow structures with one side open, and the open side of the first box body part 410 covers the open side of the second box body part 420 to form a box body 400 with the receiving part 430. Of course, the first box body part 410 and the second box body part 420 can have various shapes, such as a cylinder, a cuboid, etc.

[0089] In the battery device 100, there can be one battery cell or multiple battery cells. If there are multiple battery cells, the multiple battery cells can be connected in series, in parallel, or in a mixed connection. A mixed connection means that there are both series and parallel connections among the multiple battery cells. The multiple battery cells can be directly connected in series, in parallel, or in a mixed connection together, and then the whole formed by the multiple battery cells is accommodated in the box body 400; of course, it can also be that multiple battery cells are first connected in series, in parallel, or in a mixed connection to form a battery module 500, and then the multiple battery modules 500 are connected in series, in parallel, or in a mixed connection to form a whole and are accommodated in the box body 400.

[0090] Figure 3 is a schematic structural diagram of a battery module provided by an embodiment of the present application. In some embodiments, such as Figure 3 shown, there are multiple battery cells 110. The multiple battery cells 110 are first connected in series, parallel, or in a hybrid connection to form a battery module 500. Then, multiple battery modules 500 are connected in series, parallel, or in a hybrid connection to form a whole and are accommodated in a box.

[0091] Figure 4 is an exploded structural diagram of a battery cell provided by an embodiment of the present application. Figure 5 is a schematic diagram of an electrode assembly provided by an embodiment of the present application. Figure 6 is another schematic structural diagram of an electrode assembly provided by an embodiment of the present application.

[0092] Please refer to Figures 4 to 6 . An embodiment of the present application provides a battery cell 110. The battery cell 110 includes a housing 101 and an electrode assembly 102 accommodated in the housing 101. The electrode assembly 102 includes a first pole piece 10 and a second pole piece 20 with opposite polarities, and the first pole piece 10 and the second pole piece 20 are wound. The first pole piece 10 includes a first current collector 11 and a first film layer 12 provided on the surface of the first current collector 11. The first current collector 11 includes a first current collecting portion 111 and a second current collecting portion 112 arranged along the winding direction V, and the thickness of the second current collecting portion 112 is greater than that of the first current collecting portion 111.

[0093] In some embodiments, the electrode assembly 102 is a wound structure. The first pole piece 10 and the second pole piece 20 are wound into a wound structure.

[0094] In some embodiments, the shape of the electrode assembly 102 can be cylindrical, flat, or multi-prismatic, etc.

[0095] In some embodiments, the battery cell 110 may include a housing 101. The housing 101 is used to encapsulate components such as the electrode assembly 102 and the electrolyte. The housing 101 can be a steel shell, an aluminum shell, a plastic shell (such as polypropylene), a composite metal shell (such as a copper-aluminum composite housing 101), or an aluminum-plastic film, etc.

[0096] In some embodiments, functional components such as electrode terminals can be provided on the housing 101. The electrode terminals can be used to electrically connect to the electrode assembly 102 for outputting or inputting the electrical energy of the battery cell 110.

[0097] In some embodiments, a current collecting member can be provided in the housing 101, and the electrode assembly 102 can be electrically connected to the housing 101 or the electrode terminals provided on the housing 101 through the current collecting member.

[0098] As an example, the battery cell 110 can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. The prismatic battery cell includes a square shell battery cell, a blade-shaped battery cell, and a multi-prismatic battery, and the multi-prismatic battery is, for example, a hexagonal prism battery, etc.

[0099] The electrode assembly 102 includes a first electrode sheet 10 and a second electrode sheet 20. The polarities of the first electrode sheet 10 and the second electrode sheet 20 are opposite. Exemplarily, the first electrode sheet 10 is a negative electrode sheet, and the second electrode sheet 20 is a positive electrode sheet. Alternatively, the first electrode sheet 10 is a positive electrode sheet, and the second electrode sheet 20 is a negative electrode sheet.

[0100] Optionally, when the first electrode sheet 10 is a negative electrode sheet and the second electrode sheet 20 is a positive electrode sheet, the first current collector 11 can be a negative current collector, and the second current collector 21 can be a negative current collector. The first film layer 12 can be a negative active material layer, and the second film layer 22 can be a positive active material layer.

[0101] In some examples, the first film layer 12 can cover one side surface of the first current collector 11 along its own thickness direction. In other examples, there are two first film layers 12, and the two first film layers 12 are respectively arranged on both side surfaces of the first current collector 11 along its own thickness direction. Optionally, the first film layer 12 can be an active material layer.

[0102] In some examples, the number of winding turns of the first current collecting portion 111 is the same as that of the second current collecting portion 112. In other examples, the number of winding turns of the first current collecting portion 111 is different from that of the second current collecting portion 112. For example, the number of winding turns of the first current collecting portion 111 is greater than that of the second current collecting portion 112 to reduce the manufacturing cost of the first electrode sheet 10.

[0103] In some optional examples, the second electrode sheet 20 includes a second current collector 21 and a second film layer 22 disposed on the surface of the second current collector 21. The second current collector 21 includes a third current collecting portion and a fourth current collecting portion arranged along the winding direction V, and the thickness of the fourth current collecting portion is greater than that of the third current collecting portion.

[0104] Optionally, the number of winding turns of the fourth current collecting portion can be the same as that of the second current collecting portion 112.

[0105] In some examples, the second film layer 22 can cover one side surface of the second current collector along its own thickness direction. In other examples, there are two second film layers, and the two second film layers are respectively arranged on both side surfaces of the second current collector along its own thickness direction. Optionally, the second film layer 22 can be an active material layer.

[0106] In the embodiments of the present application, by providing the first current collector portion 111, the manufacturing cost can be reduced, the overall thickness of the electrode assembly 102 can be reduced, and thus the group margin of the battery cell 110 can be reduced. By providing the first current collector portion 111 and the second current collector portion 112, and the thickness of the second current collector portion 112 is greater than that of the first current collector portion 111, the tensile strength of the outer ring electrodes in the electrode assembly 102 can be improved, thereby reducing the risk of electrode fracture caused by expansion during the operation of the battery cell 110 and improving the reliability of the battery cell 110.

[0107] In some alternative embodiments, refer to Figure 5 , the electrode assembly 102 has a flat region FA and a bent region BA, and the connection between the first current collector portion 111 and the second current collector portion 112 is located in the bent region BA.

[0108] Exemplarily, the electrode assembly 102 may have one flat region FA and two bent regions BA respectively disposed at both ends of the flat region FA. Within the flat region FA, the electrode assembly 102 may be a flat plane. Within the bent region BA, the electrodes are bent to form a reciprocating winding structure.

[0109] The connection between the first current collector portion 111 and the second current collector portion 112 can be understood as the junction between the first current collector portion 111 and the second current collector portion 112. Since the electrode assembly 102 within the bent region BA needs to be bent, the electrode assembly 102 has a curved edge within the bent region BA. The distance between the curved edge and the housing 101 is greater than the distance between the electrode assembly 102 within the flat region FA and the housing 101. Disposing the connection in the bent region BA is beneficial to reducing the possibility of non-uniform thickness of the electrode assembly 102 within the flat region FA, and thus reducing the possibility of interference between the electrode assembly 102 within the flat region FA and the housing 101 of the battery cell 110.

[0110] In some alternative embodiments, refer to Figure 4 and Figure 5 , the first current collector portion 111 includes a first head end 111a and a first tail end 111b opposite to each other along the winding direction V, the second current collector portion 112 includes a second head end 112a and a second tail end 112b opposite to each other along the winding direction V, and the second head end 112a is connected to the first tail end 111b. The first head end 111a is the winding start end SE of the first current collector 11, and the second tail end 112b is the winding end CE of the first current collector 11.

[0111] Optionally, when the first current collector portion 111 and the second current collector portion 112 are an integral structure, the first tail end 111b is the portion with a smaller thickness at the connection of the first current collector portion 111 and the second current collector portion 112, and the second head end 112a is the portion with a larger thickness at the connection of the first current collector portion 111 and the second current collector portion 112. Optionally, the first tail end 111b and the second head end 112a may be in a transitional connection, that is, the thickness gradually increases from the first tail end 111b to the second head end 112a.

[0112] Optionally, the thickness of the first head end 111a is equal to the minimum thickness of the first tail end 111b.

[0113] Optionally, the thickness of the second head end 112a is equal to the maximum thickness of the second tail end 112b.

[0114] Optionally, the third current collector portion includes a third head end and a third tail end opposite to each other along the winding direction V, the fourth current collector portion includes a fourth head end and a fourth tail end opposite to each other along the winding direction V, the fourth head end is connected to the third tail end, the third head end is the winding start end SE of the second current collector 21, and the fourth tail end is the winding end CE of the second current collector 21.

[0115] Through the above settings in the embodiments of the present application, the first current collector 11 is a continuous structure, thereby improving the winding efficiency.

[0116] In some optional embodiments, please refer to Figure 4 , the second current collector portion 112 winds at least one turn, which is beneficial to improving the overall strength of the first current collector 11 while reducing the manufacturing cost of the first electrode sheet 10.

[0117] Optionally, the second current collector portion 112 may wind only one turn. Optionally, the first current collector 11 winds M turns and the second current collector portion 112 winds N turns. 1 ≤ N ≤ M.

[0118] Figure 7 It is a schematic structural diagram of another electrode assembly provided by the embodiments of the present application.

[0119] In some optional embodiments, please refer to Figure 5 and Figure 7 , the second current collector portion 112 includes a single-side segment 113, the outer surface of the single-side segment is not provided with the first film layer 12, and the single-side segment 113 includes the second tail end 112b.

[0120] Optionally, a part of the second current collector 112 may be a single-sided segment 113, and the other part may be a double-sided segment. The single-sided segment 113 means that a first film layer 12 is provided on the inner surface of the second current collector 112 facing the winding center, and the first film layer 12 is not provided on the outer surface of the second current collector 112 facing away from the winding center. The "outer surface" here refers to the surface on the last turn of the second current collector 21 and facing away from the winding center. The double-sided segment means that the first film layer 12 is provided on both the inner surface and the outer surface of the second current collector 112.

[0121] Of course, the entire second current collector 112 may be a single-sided segment 113. For example, the second current collector 112 is wound only once, and the entire one turn of the second current collector 112 is a single-sided segment 113.

[0122] The single-sided segment 113 including the second end 112b means that in the direction from the second end 112b to the second head 112a, the single-sided segment 113 extends from the second end 112b to a preset position. Optionally, the preset position includes the second head 112a.

[0123] In these optional embodiments, by providing the single-sided segment 113, it is beneficial to reduce the influence of the first film layer 12 on the tensile strength of the first current collector 11, and improve the tensile strength of the second current collector 112. For example, when the first pole piece 10 is a negative pole piece, the first film layer 12 includes a graphite slurry, and the graphite slurry reduces the tensile strength of the second current collector 112. The tensile strength of the single-sided segment 113 is greater than that of the first current collector 111, thereby improving the overall tensile strength of the first pole piece 10, and further reducing the possibility of pole piece fracture in the electrode assembly 102 and improving the reliability of the battery cell 110.

[0124] In some optional embodiments, the tensile strength of the second current collector 112 is greater than that of the first current collector 111 to reduce the possibility of the second current collector 112 being fractured by the expansion force, and further improve the reliability of the battery cell 110.

[0125] The tensile strength can be tested and verified by GB / T 228-2010 or YB / T 4334-2013.

[0126] Optionally, the tensile strength of the second current collector 112 being greater than that of the first current collector 111 can also be achieved by selecting different materials to prepare the first current collector 111 and the second current collector 112.

[0127] Figure 8 It is a schematic diagram of the connection between the first current collector and the second current collector in the first pole piece of an electrode assembly provided by an embodiment of the present application. Figure 9 It is a schematic diagram of the connection between the first current collector and the second current collector in the first pole piece of another electrode assembly provided by an embodiment of the present application.

[0128] In some alternative embodiments, please refer to Figure 5 、 Figure 8 and Figure 9 , the first current collector 111 and the second current collector 112 are connected by an adhesive layer 30. The adhesive layer 30 includes a conductive material to reduce the difficulty of connecting the first current collector 111 and the second current collector 112 and reduce the resistance between the first current collector 111 and the second current collector 112.

[0129] In some alternative embodiments, please refer to Figure 5 and Figure 8 , the first current collector 111 and the second current collector 112 overlap in the thickness direction to form an overlapping area. The adhesive layer 30 is disposed in the overlapping area and is located between the first current collector 111 and the second current collector 112.

[0130] Exemplarily, in the thickness direction, the first tail end 111b of the first current collector 111 and the second head end 112a of the second current collector 112 overlap, and the first tail end 111b and the second head end 112a overlap to form an overlapping area. The adhesive layer 30 is disposed in the overlapping area and is located between the first current collector 111 and the second current collector 112 to electrically connect the first current collector 111 and the second current collector 112.

[0131] Optionally, a first film layer 12 may be provided on the first current collector 111, and a second film layer 22 may be provided on the second current collector 112. The adhesive layer 30 connects the first film layer 12 and the second film layer 22 to electrically connect the first current collector 111 and the second current collector 112.

[0132] In these alternative embodiments, by providing the overlapping area and disposing the adhesive layer 30 in the overlapping area, it is beneficial to increase the bonding area between the first current collector 111 and the second current collector 112 and the adhesive layer 30, thereby reducing the possibility of separation between the first current collector 111 and the second current collector 112.

[0133] In some alternative embodiments, please refer to Figure 5 and Figure 8 , the dimension of the overlapping area in the winding direction V is ≥ 3 mm to increase the bonding area between the first current collector 111 and the second current collector 112 and the adhesive layer 30 and reduce the possibility of separation between the first current collector 111 and the second current collector 112.

[0134] Optionally, the dimension D of the overlapping area in the winding direction V may be 3 mm, 4 mm, 5 mm, 10 mm, 16 mm, 20 mm, 30 mm or other dimensions.

[0135] In some alternative embodiments, please refer to Figure 5 andFigure 9 The side walls of the first current collector portion 111 and the second current collector portion 112 are in abutting contact, and an adhesive layer 30 is provided on at least one side of the first current collector portion 111 and the second current collector portion 112 in the thickness direction.

[0136] Exemplarily, the side wall of the first tail end 111b of the first current collector portion 111 is in abutting contact with the side wall of the second head end 112a of the second current collector portion 112, and the adhesive layer 30 connects the first current collector portion 111 and the second current collector portion 112 together on the same side in the thickness direction.

[0137] Optionally, the adhesive layer 30 may be provided only on one side of the first current collector portion 111 and the second current collector portion 112 in the thickness direction. For example, the adhesive layer 30 is provided on the side of the first current collector portion 111 facing the winding center and the side of the second current collector portion 112 facing the winding center. Alternatively, the adhesive layer 30 is provided on the side of the first current collector portion 111 facing away from the winding center and the side of the second current collector portion 112 facing away from the winding center.

[0138] Optionally, the number of the adhesive layers 30 may include two, and the two adhesive layers 30 are respectively provided on opposite sides of the first current collector portion 111 and the second current collector portion 112 in the thickness direction.

[0139] In these optional embodiments, through the above settings, it is beneficial to reduce the overall thickness at the connection of the first current collector portion 111 and the second current collector portion 112, thereby reducing the possibility of interference between the electrode assembly 102 and the housing 101 caused by the outward protrusion at the connection of the first current collector portion 111 and the second current collector portion 112, and improving the energy density of the battery cell 110.

[0140] Figure 10 It is a schematic diagram of the connection between the first current collector portion and the second current collector portion in the first pole piece of another electrode assembly provided by the embodiment of the present application. Figure 11 It is a schematic diagram of the connection between the first current collector portion and the second current collector portion in the first pole piece of another electrode assembly provided by the embodiment of the present application.

[0141] In some optional embodiments, please refer to Figure 5 , Figure 10 and Figure 11 , the first current collector portion 111 includes a first non-coated area, the second current collector portion 112 includes a second non-coated area, the first non-coated area and the second non-coated area are not provided with the first film layer 12, and the first non-coated area and the second non-coated area are both connected to the adhesive layer 30.

[0142] Exemplarily, a first non - coating area is provided at the first tail end 111b, and the first tail end 111b exposes a partial surface of the first current collector 111. A second non - coating area is provided at the second head end 112a, and the second head end 112a exposes a partial surface of the second current collector 112. The adhesive layer 30 is connected to the exposed surfaces of the first current collector 111 and the second current collector 112.

[0143] Exemplarily, as Figure 10 described, when the first current collector 111 and the second current collector 112 overlap in the thickness direction, in the overlapping area, the surface of the first current collector 111 facing the second current collector 112 and the surface of the second current collector 112 facing the first current collector 111 are connected through the adhesive layer 30, shortening the conductive distance between the first current collector 111 and the second current collector 112, such that the adhesive layer 30 and the first film layer 12 as well as the second film layer 22 share the space in the thickness direction, so as to reduce the overall thickness of the first electrode tab 10, thereby reducing the overall thickness of the electrode assembly 102 and increasing the energy density of the battery cell 110. Optionally, the thickness of the adhesive layer 30 is greater than, less than, or equal to the thickness of the first film layer 12. And / or, the thickness of the adhesive layer 30 is greater than, less than, or equal to the thickness of the second film layer 22.

[0144] Exemplarily, as Figure 11 described, when the adhesive layer 30 is disposed on the two side surfaces of the first current collector 111 and the second current collector 112 in the thickness direction, the adhesive layer 30 can be an integral body or two. For example, when the adhesive layer 30 is one, the adhesive layer wraps the connection part of the first current collector 111 and the second current collector 112 to further improve the connection strength between the first current collector 111 and the second current collector 112.

[0145] Figure 12 It is a schematic diagram of the connection part between the first current collector and the second current collector in the first electrode tab of another electrode assembly provided by an embodiment of the present application.

[0146] In some optional embodiments, please refer to Figure 5 and Figure 12 , the second current collector 112 includes a first stacked portion 112c and a second stacked portion 112d which are stacked, and the first stacked portion 112c and the first current collector 111 are an integral structure.

[0147] Optionally, the first stacked portion 112c and the second stacked portion 112d can be fixedly connected by means of adhesion, welding, snap - connection, etc.

[0148] Optionally, the thickness of the first stacked portion 112c is the same as the thickness of the first current collector 111.

[0149] Optionally, the thickness of the first stacked portion 112c may be greater than, less than, or equal to the thickness of the second stacked portion 112d.

[0150] In these alternative embodiments, by providing the first stacked portion 112c and the second stacked portion 112d, it is beneficial to reduce the possibility of separation between the first current collector portion 111 and the second current collector portion 112 while improving the flexibility of the arrangement of the second current collector portion 112.

[0151] In some alternative embodiments, the thickness of the second current collector portion 112 is greater than or equal to 6 μm to further increase the tensile strength of the second current collector portion 112 and reduce the possibility of the second current collector portion 112 breaking under the action of the expansion force.

[0152] Optionally, the thickness of the second current collector portion 112 may be 6 μm, 8 μm, 10 μm, 13 μm, 18 μm, 24 μm or other dimensions.

[0153] In a second aspect, an embodiment of the present application provides a battery device 100, including the battery cell 110 in any of the foregoing embodiments.

[0154] In a third aspect, an embodiment of the present application provides an electrical device, including the battery device 100 in any of the foregoing embodiments, and the battery device is used to provide electrical energy.

[0155] According to some embodiments of the present application, please refer to Figures 4 to 8 , the battery cell 110 includes a housing 101 and an electrode assembly 102 accommodated in the housing. The electrode assembly includes a first pole piece 10 and a second pole piece 20 with opposite polarities, and the first pole piece and the second pole piece are wound. The first pole piece 10 includes a first current collector 11 and a first film layer 12 provided on the surface of the first current collector. The first current collector 11 includes a first current collector portion 111 and a second current collector portion 112 arranged along the winding direction V, and the thickness of the second current collector portion is greater than the thickness of the first current collector portion 111.

[0156] The electrode assembly 102 has a flat region FA and a bent region BA, and the connection between the first current collector portion 111 and the second current collector portion 112 is located in the bent region BA. The second current collector portion 112 winds around once. The second current collector portion includes a single-sided segment 113, and the first film layer 12 is not provided on the outer surface of the single-sided segment. The single-sided segment 113 includes a second tail end 112b. The first pole piece 10 is a negative pole piece.

[0157] The first current collector portion 111 and the second current collector portion 112 overlap in the thickness direction to form an overlapping region, and an adhesive layer is provided in the overlapping region and is located between the first current collector portion 111 and the second current collector portion 112.

[0158] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be covered by the scope of the claims and the specification of the present application. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell, characterized in that, It includes a housing and an electrode assembly accommodated in the housing. The electrode assembly includes a first pole piece and a second pole piece with opposite polarities, and the first pole piece and the second pole piece are wound. The first pole piece includes a first current collector and a first film layer disposed on the surface of the first current collector. The first current collector includes a first current collecting portion and a second current collecting portion disposed along the winding direction, and the thickness of the second current collecting portion is greater than that of the first current collecting portion.

2. The battery cell according to claim 1, wherein The electrode assembly has a flat region and a bent region, and the connection portion of the first current collecting portion and the second current collecting portion is located in the bent region.

3. The battery cell according to claim 1, wherein, The first current collecting portion includes a first head end and a first tail end opposite to each other along the winding direction, and the second current collecting portion includes a second head end and a second tail end opposite to each other along the winding direction. The second head end is connected to the first tail end; the first head end is the winding starting end of the first current collector, and the second tail end is the winding ending end of the first current collector.

4. The battery cell according to claim 3, wherein, The second current collecting portion winds at least one turn.

5. The battery cell according to claim 3, characterized in that, The second current collecting portion includes a single-side segment, and the first film layer is not provided on the outer surface of the single-side segment. The single-side segment includes the second tail end.

6. The battery cell according to claim 1, characterized in that, The first pole piece is a negative pole piece.

7. The battery cell according to claim 1, wherein The tensile strength of the second current collecting portion is greater than that of the first current collecting portion.

8. The battery cell according to claim 1, characterized in that, The first current collecting portion and the second current collecting portion are connected by an adhesive layer, and the adhesive layer includes a conductive material.

9. The battery cell according to claim 8, wherein, The first current collecting portion and the second current collecting portion overlap in the thickness direction to form an overlapping region. The adhesive layer is disposed in the overlapping region and is located between the first current collecting portion and the second current collecting portion.

10. The battery cell according to claim 9, characterized in that, The size of the overlapping region in the winding direction is ≥3 mm.

11. The battery cell according to claim 8, wherein, The side walls of the first current collecting portion and the second current collecting portion are in abutting contact, and the adhesive layer is provided on at least one side of the first current collecting portion and the second current collecting portion in the thickness direction.

12. The battery cell according to claim 9 or 11, characterized in that, The first current collecting portion includes a first non-coated region, and the second current collecting portion includes a second non-coated region. The first film layer is not provided in both the first non-coated region and the second non-coated region, and both the first non-coated region and the second non-coated region are connected to the adhesive layer.

13. The battery cell according to claim 1, characterized in that, The second current collecting portion includes a first stacked portion and a second stacked portion stacked, and the first stacked portion and the first current collecting portion are an integral structure.

14. The battery cell according to claim 1, wherein The thickness of the second current collecting portion is greater than or equal to 6 μm.

15. A battery device, characterized in that, It includes a battery cell according to any one of claims 1 to 14.

16. An electrical device, characterized in that, It includes a battery device according to claim 15, and the battery device is used to provide electric energy.

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