Electrode assembly, battery cell, battery and electrical device

Abstract

The embodiments of the present application provide an electrode assembly, a manufacturing method and a manufacturing system thereof, a battery cell, a battery, and an electrical device. The electrode assembly of the embodiments of the present application includes a first electrode sheet, a second electrode sheet, and a first separator. The polarities of the first electrode sheet and the second electrode sheet are opposite. The first separator is used to separate the first electrode sheet and the second electrode sheet. The first electrode sheet, the second electrode sheet, and the first separator are wound along a winding direction. The electrode assembly has a bending area, and the bending area is provided with a second separator. The second separator is stacked with the first separator and is used to separate the adjacent first electrode sheet and the second electrode sheet; at least part of the ions released from the first electrode sheet can pass through the first separator and the second separator and be embedded in the second electrode sheet. The first separator and the second separator jointly separate the first electrode sheet and the second electrode sheet in the bending area to reduce the short circuit problem of the electrode assembly caused by damage to the separator.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202111062600.7, filed on September 10, 2021, entitled “Electrode assembly and related battery cells, batteries, devices and manufacturing methods,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of battery technology, and more particularly, to an electrode assembly, a manufacturing method and a manufacturing system thereof, a battery cell, a battery, and an electric device. Background Art

[0004] Battery cells are widely used in electronic devices such as mobile phones, laptops, electric bicycles, electric cars, electric airplanes, electric boats, electric toy cars, electric toy boats, electric toy airplanes, and power tools. Battery cells can include nickel-cadmium battery cells, nickel-metal hydride battery cells, lithium-ion battery cells, and secondary alkaline zinc-manganese battery cells.

[0005] In the development of battery technology, in addition to improving the performance of battery cells, safety is also an issue that cannot be ignored. If the safety of a battery cell cannot be guaranteed, the battery cell will be unusable. Therefore, how to enhance the safety of battery cells is a technical issue that needs to be addressed urgently in battery technology. Summary of the Invention

[0006] The present application provides an electrode assembly, a manufacturing method and a manufacturing system thereof, a battery cell, a battery, and an electrical device, which can improve safety.

[0007] In a first aspect, embodiments of the present application provide an electrode assembly comprising a first electrode piece, a second electrode piece, and a first separator, wherein the first electrode piece and the second electrode piece have opposite polarities, the first separator is used to separate the first electrode piece and the second electrode piece, and the first electrode piece, the second electrode piece, and the first separator are wound along a winding direction. The electrode assembly has a bending region, wherein a second separator is disposed in the bending region, and the second separator is stacked with the first separator and is used to separate the adjacent first and second electrode pieces; at least a portion of the ions released from the first electrode piece can pass through the first and second separators and embed into the second electrode piece.

[0008] In the present application, the first separator and the second separator jointly separate the first electrode piece and the second electrode piece in the bending region. Even if lithium deposition occurs in the bending region, or burrs are generated in the electrode piece during bending, it is difficult for lithium dendrites or burrs to pierce the first separator and the second separator at the same time, thereby reducing the probability of conduction between the first electrode piece and the second electrode piece, effectively reducing the short circuit problem caused by damage to the separator in the electrode assembly, and thus effectively reducing the risk of failure of the electrode assembly and improving the service life and safety of the electrode assembly. Both the first separator and the second separator are permeable to ions, which can reduce the barrier to ions and ensure the capacity of the electrode assembly.

[0009] In some embodiments, the second spacer has a thickness greater than that of the first spacer.

[0010] In the above embodiment, the second isolating member is more difficult to be punctured than the first isolating member, which can effectively reduce the risk of damage to the second isolating member and improve safety.

[0011] In some embodiments, the second separator includes a plurality of separator layers, and the plurality of separator layers are stacked along a thickness direction of the second separator.

[0012] In the above embodiment, the multi-layer structure can improve the strength of the second separator, increase the difficulty of puncturing the second separator, and improve safety.

[0013] In some embodiments, adjacent release layers are bonded to each other.

[0014] In the above embodiment, the multiple isolation layers are bonded together, which can reduce the risk of offset between the multiple isolation layers during the winding process of the electrode assembly and ensure the protective effect of the second isolation member in the bending area.

[0015] In some embodiments, the plurality of isolation layers include a first isolation layer and a second isolation layer disposed adjacent to each other, the first isolation layer being located between the second isolation layer and the first separator, and an end portion of the second isolation layer being offset from an end portion of the first isolation layer in the winding direction.

[0016] In the above embodiment, the end of the second isolation layer is staggered with the end of the first isolation layer, so that the end of the second isolation layer and the end of the first isolation layer can squeeze different areas of the pole piece, reduce stress concentration, reduce the risk of pole piece cracking, and improve the performance of the pole piece.

[0017] In some embodiments, in the winding direction, both ends of the second insulating layer extend beyond the first insulating layer and are attached to the first insulating member.

[0018] In the above embodiment, the second isolation layer is attached to the first isolation member and can limit the movement of the first isolation layer in the winding direction. This can reduce the risk of the first isolation layer and the second isolation layer being offset or misaligned along the winding direction during charging and discharging, ensure the protective effect of the second isolation member in the bending area, and improve safety.

[0019] In some embodiments, the electrode assembly further includes a straight region connected to the bent region, the first separator is entirely located in the bent region, and both ends of the second separator along the winding direction are located in the straight region.

[0020] In the above embodiment, the first and second isolation layers can simultaneously provide protection in the bend region, reducing the risk of short circuits and improving safety. The entire first isolation layer is located in the bend region, preventing it from affecting ion transport in the straight region and ensuring charge and discharge performance in the straight region. The second isolation layer's ends along the winding direction are located in the straight region, allowing the ends of the second isolation layer to be offset from the ends of the first isolation layer, reducing stress concentration.

[0021] In some embodiments, the first isolation layer is attached to the first isolation member.

[0022] The above embodiment can reduce the risk of the first isolation layer being offset or misplaced along the winding direction, ensure the protective effect of the first isolation layer in the bending area, and improve safety.

[0023] In some embodiments, the material of the isolation layer is the same as that of the first isolation member, and the thickness of the isolation layer is equal to the thickness of the first isolation member.

[0024] In the above embodiment, the first isolating member and the second isolating member can be made of isolating members of the same specification, which can simplify the process and reduce costs.

[0025] In some embodiments, the porosity of the second separator is greater than or equal to the porosity of the first separator.

[0026] In the above embodiment, the second separator has good ion permeability, so as to reduce the barrier of the second separator to ions and ensure the capacity of the electrode assembly.

[0027] In some embodiments, within the bending region, a second spacer is provided between at least the innermost adjacent first pole piece and the second pole piece.

[0028] The above embodiment can set a second separator in the area where the lithium plating problem is serious, thereby effectively reducing the short circuit problem of the electrode assembly caused by damage to the separator, and improving the service life and safety of the electrode assembly.

[0029] In some embodiments, a plurality of second spacers are provided in the bending region, and adjacent second spacers are separated by the first pole piece or the second pole piece. Among adjacent second spacers, the thickness of the inner second spacer is greater than the thickness of the outer second spacer.

[0030] In the above embodiment, the inner second separator has a larger thickness to minimize the risk of puncture; the outer second separator has a low risk of puncture, so it can have a smaller thickness to save the use of the second separator and increase the energy density of the electrode assembly.

[0031] In some embodiments, the electrode assembly further includes a straight region connected to the bent region, and both ends of the second separator along the winding direction are located in the straight region.

[0032] In the above embodiment, the second isolating member can completely separate the first pole piece from the second pole piece to improve safety.

[0033] In some embodiments, the second spacer is attached to an outer surface of the first spacer.

[0034] In the above embodiment, the second isolating member is attached to the outer surface of the first isolating member, which can not only reduce the risk of the second isolating member being offset or misplaced along the winding direction during charging and discharging, but also enable the second isolating member to be stretched under the action of the first isolating member to reduce the risk of wrinkling of the second isolating member.

[0035] In some embodiments, the second electrode sheet is a negative electrode sheet, and the second separator is attached to an outer surface of the second electrode sheet.

[0036] In the above embodiment, the second isolating member is attached to the outer surface of the second pole piece, and the second isolating member is stretched under the action of the second pole piece, which can reduce the risk of wrinkling of the second isolating member.

[0037] In a second aspect, an embodiment of the present application provides a battery cell comprising a housing and an electrode assembly according to any one of the embodiments of the first aspect, wherein the electrode assembly is housed in the housing.

[0038] In a third aspect, an embodiment of the present application provides a battery comprising a plurality of battery cells according to the second aspect.

[0039] In a fourth aspect, an embodiment of the present application provides an electrical device, comprising a battery cell according to the second aspect, the battery cell being used to provide electrical energy.

[0040] In a fifth aspect, an embodiment of the present application provides a method for manufacturing a battery assembly, comprising:

[0041] Providing a first pole piece, a second pole piece, a first separator and a second separator;

[0042] Winding the first pole piece, the second pole piece and the first separator along a winding direction to form a bending area;

[0043] Among them, the polarities of the first pole piece and the second pole piece are opposite, and the first isolating member is used to separate the first pole piece and the second pole piece; a second isolating member is provided in the bending area, and the second isolating member is stacked with the first isolating member and is used to separate the adjacent first pole piece and the second pole piece; at least part of the ions escaped from the first pole piece can pass through the first isolating member and the second isolating member and be embedded in the second pole piece.

[0044] In a sixth aspect, an embodiment of the present application provides a manufacturing system for a battery assembly, comprising a providing device and a winding device. The providing device is used to provide a first pole piece, a second pole piece, a first separator and a second separator. The winding device is used to wind the first pole piece, the second pole piece and the first separator along a winding direction to form a bending area. The polarities of the first pole piece and the second pole piece are opposite, and the first separator is used to separate the first pole piece and the second pole piece; a second separator is provided in the bending area, and the second separator is stacked with the first separator and is used to separate the adjacent first pole piece and the second pole piece; at least part of the ions released from the first pole piece can pass through the first separator and the second separator and be embedded in the second pole piece. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0046] Figure 1 A schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0047] Figure 2 An exploded schematic diagram of a battery provided in some embodiments of the present application;

[0048] Figure 3 Schematic diagram of an explosion of a battery cell provided in some embodiments of the present application;

[0049] Figure 4 A schematic diagram of the structure of an electrode assembly provided in some embodiments of the present application;

[0050] Figure 5 for Figure 4 An enlarged schematic diagram of a portion of the electrode assembly shown;

[0051] Figure 6 Schematic diagram of a partial structure of an electrode assembly provided in some other embodiments of the present application;

[0052] Figure 7A schematic diagram of a partial structure of an electrode assembly provided in some other embodiments of the present application;

[0053] Figure 8 A schematic diagram of a partial structure of an electrode assembly provided in some further embodiments of the present application;

[0054] Figure 9 A schematic flow chart of a method for manufacturing a battery assembly according to some embodiments of the present application;

[0055] Figure 10 A schematic block diagram of a manufacturing system for an electrode assembly provided in some embodiments of the present application.

[0056] In the drawings, the drawings are not drawn to scale. DETAILED DESCRIPTION

[0057] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0058] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of the application are for the purpose of describing specific embodiments only 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-mentioned drawings 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-secondary relationship.

[0059] In the description of the present application, it should be understood that the terms "center", "lateral", "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do 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 understood as a limitation on the present application.

[0060] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0061] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0062] The term "and / or" in this document simply describes a relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can mean: A exists alone, A and B exist simultaneously, or B exists alone. Additionally, the character " / " in this document generally indicates that the related objects are in an "or" relationship.

[0063] The term "multiple" in this application refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0064] In this application, battery cells may include lithium-ion secondary battery cells, lithium-ion primary battery cells, lithium-sulfur battery cells, sodium-lithium-ion battery cells, sodium-ion battery cells, or magnesium-ion battery cells, etc., and the embodiments of this application do not limit this. Battery cells may be cylindrical, flat, rectangular, or other shapes, etc., and the embodiments of this application do not limit this. Battery cells are generally divided into three types according to the packaging method: cylindrical battery cells, square battery cells, and soft-pack battery cells, and the embodiments of this application do not limit this.

[0065] A battery cell includes an electrode assembly and an electrolyte. The electrode assembly consists of a positive electrode sheet, a negative electrode sheet, and a separator. A battery cell primarily operates by the movement of metal ions between the positive and negative electrode sheets. The positive electrode sheet includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive current collector. The current collector uncoated with the positive active material layer protrudes from the current collector coated with the positive active material layer, and the current collector uncoated with the positive active material layer serves as the positive electrode tab. For lithium-ion batteries, for example, the positive current collector can be made of aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. The negative electrode sheet includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative current collector. The current collector uncoated with the negative active material layer protrudes from the current collector coated with the negative active material layer, and the current collector uncoated with the negative active material layer serves as the negative electrode tab. The negative current collector can be made of copper, and the negative active material can be carbon or silicon, among others. To ensure high current flow without melting, multiple positive electrode tabs are stacked together, and multiple negative electrode tabs are stacked together. Separators can be made of materials such as PP (polypropylene) or PE (polyethylene). The development of battery technology requires simultaneous consideration of multiple design factors, including performance parameters such as energy density, cycle life, discharge capacity, and charge / discharge rate. Furthermore, battery safety must be considered.

[0066] The battery referred to in the embodiments of this application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in this application may include a battery module or a battery pack. A battery generally includes a casing that encloses one or more battery cells. The casing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0067] The separator has electronic insulation properties and is disposed between the positive electrode sheet and the negative electrode sheet. Its main function is to prevent the positive electrode sheet and the negative electrode sheet from contacting each other, thereby causing an internal short circuit in the electrode assembly. The separator has a large number of through-holes, which can ensure the free passage of electrolyte ions. In particular, the separator has good permeability to lithium ions. Exemplarily, the separator includes an isolation base layer and a functional layer located on the surface of the isolation base layer. The isolation base layer can be at least one of polypropylene, polyethylene, ethylene-propylene copolymer, polybutylene terephthalate, etc., and the functional layer can be a mixture layer of ceramic oxide and binder.

[0068] Isolators play a very important role in electrode assemblies and can directly lead to short circuits, reduced performance and lifespan of electrode assemblies.

[0069] When a battery cell is charging, metal ions are released from the positive electrode active material layer and embedded in the negative electrode active material layer. However, some abnormal situations may occur, leading to the precipitation of metal ions. Taking lithium-ion battery cells as an example, due to insufficient lithium embedding space in the negative electrode active material layer, too much resistance to lithium ion embedding in the negative electrode active material layer, or lithium ions being released too quickly from the positive electrode active material layer, the released lithium ions cannot be embedded in the negative electrode active material layer of the negative electrode sheet in equal amounts. The lithium ions that cannot be embedded in the negative electrode sheet can only gain electrons on the surface of the negative electrode sheet, thus forming metallic lithium. This is the lithium precipitation phenomenon.

[0070] During the research and development process, the inventors also discovered that wound electrode assemblies are more prone to lithium deposition in their bend areas. Further research revealed that the primary cause of this lithium deposition is the need to bend the positive and negative electrode sheets located in the bend areas. This bending process can lead to stress concentration in the positive and negative electrode active material layers, which can cause the respective active materials to detach. This detachment of active material, particularly from the negative electrode sheet, can result in the negative electrode active material layer of the negative electrode sheet having fewer lithium insertion sites than the positive electrode active material layer of the adjacent positive electrode sheet, triggering lithium deposition.

[0071] When lithium plating is serious, the released lithium ions can form lithium crystals on the surface of the negative electrode. However, since the separator is thin, the lithium crystals can easily puncture the separator, causing the risk of short circuit between the adjacent positive and negative electrodes, posing a safety hazard.

[0072] In addition, since the positive or negative electrode sheets are prone to certain microcracks and burrs during the winding and bending process, the separators are easily punctured under greater stress, causing the electrode assembly to short-circuit, which in turn can easily lead to thermal runaway phenomena such as fire and explosion in the battery cells.

[0073] In view of this, the inventor of this application proposed an electrode assembly, which increases the number of layers of insulating parts in the bending area, thereby reducing the probability of damage to the insulating parts in the electrode assembly, reducing the risk of internal short circuit between the first and second pole pieces, and improving service life and safety.

[0074] The electrode assembly described in the embodiments of the present application is applicable to battery cells, batteries, and electrical devices using batteries.

[0075] Electrical devices may include vehicles, mobile phones, portable devices, laptop computers, ships, spacecraft, electric toys, and electric tools, etc. Vehicles may include fuel vehicles, gas vehicles, or new energy vehicles. New energy vehicles may include pure electric vehicles, hybrid vehicles, or extended-range vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

[0076] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device.

[0077] Figure 1 This is a schematic diagram of the structure of a vehicle provided in some embodiments of the present application. Figure 1 As shown, a battery 2 is provided inside the vehicle 1, and the battery 2 can be provided at the bottom, head, or tail of the vehicle 1. The battery 2 can be used to power the vehicle 1, for example, the battery 2 can be used as an operating power source for the vehicle 1.

[0078] The vehicle 1 may further include a controller 3 and a motor 4 . The controller 3 is used to control the battery 2 to supply power to the motor 4 , for example, to meet the power requirements of the vehicle 1 during startup, navigation, and driving.

[0079] In some embodiments of the present application, the battery 2 can not only serve as the operating power source of the vehicle 1, but also serve as the driving power source of the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0080] Figure 2 Schematic diagram of the explosion of the battery provided in some embodiments of the present application. Figure 2 As shown, the battery 2 includes a box body 5 and a battery cell 6 , and the battery cell 6 is accommodated in the box body 5 .

[0081] The housing 5 is used to accommodate the battery cells 6 and can have various structures. In some embodiments, the housing 5 can include a first housing portion 51 and a second housing portion 52. The first housing portion 51 and the second housing portion 52 overlap each other and together define a storage space 53 for accommodating the battery cells 6. The second housing portion 52 can be a hollow structure with one end open. The first housing portion 51 is a plate-like structure. The first housing portion 51 overlaps the open side of the second housing portion 52 to form the housing 5 with the storage space 53. The first housing portion 51 and the second housing portion 52 can also each be a hollow structure with one end open. The open side of the first housing portion 51 overlaps the open side of the second housing portion 52 to form the housing 5 with the storage space 53. Of course, the first housing portion 51 and the second housing portion 52 can have various shapes, such as a cylinder, a rectangular parallelepiped, etc.

[0082] In order to improve the sealing performance after the first box body 51 and the second box body 52 are connected, a sealing member, such as a sealant, a sealing ring, etc., may also be provided between the first box body 51 and the second box body 52 .

[0083] Assuming that the first box portion 51 covers the top of the second box portion 52 , the first box portion 51 can also be referred to as an upper box cover, and the second box portion 52 can also be referred to as a lower box.

[0084] The battery 2 includes multiple battery cells 6. These multiple battery cells 6 can be connected in series, in parallel, or in a hybrid configuration. A hybrid configuration refers to a combination of series and parallel connections within the multiple battery cells 6. The multiple battery cells 6 can be directly connected in series, in parallel, or in a hybrid configuration, and then the entire battery system 6 is housed within the housing 5. Alternatively, multiple battery cells 6 can be first connected in series, in parallel, or in a hybrid configuration to form a battery module, and then the multiple battery modules can be connected in series, in parallel, or in a hybrid configuration to form a single unit housed within the housing 5.

[0085] Figure 3 Schematic diagram of the explosion of a battery cell provided in some embodiments of the present application. Battery cell 6 refers to the smallest unit that constitutes battery 2. Figure 3 As shown, the battery cell 6 includes a housing, an electrode assembly 100 and other functional components, and the electrode assembly 100 is accommodated in the housing.

[0086] In some embodiments, the housing includes an end cap 61 and a shell 62 .

[0087] The end cap 61 refers to a component that covers the opening of the shell 62 to isolate the internal environment of the battery cell 6 from the external environment. Without limitation, the shape of the end cap 61 can be adapted to the shape of the shell 62 to match the shell 62. Optionally, the end cap 61 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that the end cap 61 is not easily deformed when squeezed or collided, so that the battery cell 6 can have a higher structural strength and the safety performance can also be improved. Functional components such as electrode terminals can be provided on the end cap 61. The electrode terminal can be used to electrically connect to the electrode assembly 100 for outputting or inputting electrical energy of the battery cell 6.

[0088] In some embodiments, the end cap 61 may also be provided with a pressure relief mechanism for releasing internal pressure when the internal pressure or temperature of the battery cell 6 reaches a threshold. The end cap 61 may also be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this embodiment of the present application does not impose any particular limitation on this.

[0089] In some embodiments, an insulating member may be provided inside the end cap 61 to isolate the electrical connection components in the housing 62 from the end cap 61 to reduce the risk of short circuit. For example, the insulating member may be made of plastic, rubber, or the like.

[0090] The housing 62 is a component that cooperates with the end cap 61 to form the internal environment of the battery cell 6. This internal environment can be used to accommodate the electrode assembly 100, electrolyte, and other components. The housing 62 and end cap 61 can be separate components. An opening can be provided in the housing 62, and the end cap 61 is placed over the opening to form the internal environment of the battery cell 6. Alternatively, the end cap 61 and housing 62 can be integrated. Specifically, the end cap 61 and housing 62 can form a common connection surface before other components are inserted into the housing. When the interior of the housing 62 needs to be enclosed, the end cap 61 is placed over the housing 62. The housing 62 can have a variety of shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the housing 62 can be determined based on the specific shape and size of the electrode assembly 100. The housing 62 can be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this embodiment of the present application does not impose any particular limitations on this.

[0091] The electrode assembly 100 is a component of the battery cell 6 that is immersed in the electrolyte to produce an electrochemical reaction. One or more electrode assemblies 100 may be contained in the shell 62. The electrode assembly 100 is mainly formed by winding a positive electrode sheet and a negative electrode sheet, and an isolation member is usually provided between the positive electrode sheet and the negative electrode sheet. The parts of the positive electrode sheet and the negative electrode sheet with active materials constitute the main body of the electrode assembly 100, and the parts of the positive electrode sheet and the negative electrode sheet without active materials each constitute a tab. The positive electrode tab and the negative electrode tab may be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery cell, the positive electrode active material and the negative electrode active material react with the electrolyte, and the tabs connect the electrode terminals to form a current loop.

[0092] Figure 4 A schematic diagram of the structure of an electrode assembly provided in some embodiments of the present application; Figure 5 for Figure 4 An enlarged schematic diagram of a portion of the electrode assembly is shown.

[0093] like Figure 4 and Figure 5 As shown, the electrode assembly 100 of the embodiment of the present application includes a first electrode sheet 110, a second electrode sheet 120, and a first separator 131. The first electrode sheet 110 and the second electrode sheet 120 have opposite polarities. The first separator 131 is used to separate the first electrode sheet 110 and the second electrode sheet 120. The first electrode sheet 110, the second electrode sheet 120, and the first separator 131 are wound along a winding direction X. The electrode assembly 100 has a bending region B, and the bending region B is provided with a second separator 132. The second separator 132 is stacked with the first separator 131 and is used to separate the adjacent first electrode sheet 110 and the second electrode sheet 120. At least some of the ions released from the first electrode sheet 110 can pass through the first separator 131 and the second separator 132 and be embedded in the second electrode sheet 120.

[0094] In this embodiment, the winding direction X is the direction in which the first pole piece 110, the second pole piece 120 and the first separator 131 are wound from the inside to the outside. For example, in the figure, the winding direction X is counterclockwise.

[0095] One of the first electrode sheet 110 and the second electrode sheet 120 is a positive electrode sheet, and the other is a negative electrode sheet.

[0096] Both the first separator 131 and the second separator 132 have a large number of micropores extending therethrough, enabling the free passage of metal ions. For example, the first separator 131 and the second separator 132 are highly permeable to lithium ions and are substantially impermeable to the passage of lithium ions. For example, the first separator 131 and the second separator 132 can be made of PP (polypropylene) or PE (polyethylene).

[0097] The first isolating member 131 and the second isolating member 132 may be made of the same material or different materials. In this embodiment, the thickness of the first isolating member 131 and the second isolating member 132 is not limited.

[0098] The isolation member mentioned in this application may also be referred to as an isolation membrane, which is represented by a line in the figure, but in fact the isolation member also has thickness.

[0099] The first pole piece 110, the second pole piece 120, and the first separator 131 are all strip-shaped structures. In some embodiments, two first separators 131 are provided. In this application, the first pole piece 110, one first separator 131, the second pole piece 120, and another first separator 131 can be stacked in sequence, and then wound two or more times to form a wound structure.

[0100] In this application, the winding device winds the first electrode sheet 110, the second electrode sheet 120, and the first separator 131 into a plurality of turns. Each turn can be constructed with several layers. A turn refers to a point on the electrode assembly 100 as the starting point, and a circle along the winding direction X is used to reach another point to locate the ending point. The ending point is in a straight line with the starting point and the center of the turn, and the starting point is between the ending point and the center of the turn. Each turn includes a first electrode sheet layer, a first separator layer, a second electrode sheet layer, and a first separator layer in sequence. The first separator 131 is used to isolate the first electrode sheet 110 and the second electrode sheet 120 of adjacent turns or adjacent layers in the same turn.

[0101] The first isolating member 131 should be understood as an isolating member between the first pole piece 110 and the second pole piece 120 in the related art, that is, a basic isolating member, and the second isolating member 132 should be understood as an added isolating member, that is, an additional isolating member.

[0102] The electrode assembly 100 may be in various shapes. For example, the electrode assembly 100 may be cylindrical, flat, prism (eg, triangular, quadrangular, or hexagonal), or other shapes.

[0103] The first electrode piece 110 and the second electrode piece 120 each include a plurality of bent portions 150 located in a bending region B. The bending region B is a region of the electrode assembly 100 having a bent structure. The portion of the first electrode piece 110 located in the bending region B (i.e., the bent portion 150 of the first electrode piece 110) and the portion of the second electrode piece 120 located in the bending region B (i.e., the bent portion 150 of the second electrode piece 120) are both bent. Exemplarily, the bent portion 150 of the first electrode piece 110 and the bent portion 150 of the second electrode piece 120 are generally bent into an arc shape.

[0104] In this embodiment, the bending region B may have one second isolation member 132 or may have multiple second isolation members 132 .

[0105] The second isolating member 132 is stacked between the pole piece and the first isolating member 131, wherein the pole piece can be the first pole piece 110 or the second pole piece 120. In some examples, the second isolating member 132 can be independently arranged between the pole piece and the first isolating member 131, that is, the second isolating member 132 is separately stacked with the pole piece and the first isolating member 131, and there is no adhesion or other connection relationship between the second isolating member 132 and the pole piece, and between the second isolating member 132 and the first isolating member 131. In other examples, the second isolating member 132 can also be attached to the surface of the pole piece or to the surface of the first isolating member 131; attachment refers to an adhesive connection, for example, the second isolating member 132 can be attached to the pole piece or the first isolating member 131 by bonding or other means.

[0106] The second separator 132 may be entirely located in the bending region B of the electrode assembly 100 , or may be only partially located in the bending region B of the electrode assembly 100 .

[0107] In this embodiment, the first separator 131 and the second separator 132 jointly separate the first electrode 110 and the second electrode 120 in the bending region B. Even if lithium deposition occurs in the bending region B, or burrs are generated in the electrode during bending, it is difficult for lithium dendrites or burrs to simultaneously pierce the first separator 131 and the second separator 132, thereby reducing the probability of conduction between the first electrode 110 and the second electrode 120, effectively reducing the short circuit problem caused by damage to the separator in the electrode assembly 100, and thus effectively reducing the risk of failure of the electrode assembly 100 and improving the service life and safety of the electrode assembly 100. The first separator 131 and the second separator 132 are both ion-permeable, which can reduce the barrier to ions and ensure the capacity of the electrode assembly 100.

[0108] In some embodiments, the thickness of the second spacer 132 is greater than the thickness of the first spacer 131 .

[0109] In this embodiment, the second isolation member 132 is more difficult to be punctured than the first isolation member 131 , which can effectively reduce the risk of damage to the second isolation member 132 and improve safety.

[0110] In some embodiments, the porosity of the second separator 132 is greater than or equal to the porosity of the first separator 131 .

[0111] Porosity refers to the percentage of pore volume in a bulk material to the total volume of the material in its natural state. Generally, porosity is measured using the true density method.

[0112] In this embodiment, the second separator 132 has good ion permeability, so as to reduce the barrier effect of the second separator 132 on ions and ensure the capacity of the electrode assembly 100 .

[0113] In some embodiments, the porosity of the second separator 132 is greater than the porosity of the first separator 131 .

[0114] In some embodiments, within the bending region B, a second isolation member 132 is provided between at least the innermost adjacent first pole piece 110 and second pole piece 120 .

[0115] In the bending region B, the innermost first pole piece 110 and the second pole piece 120 are more prone to lithium plating and burr problems. Specifically, compared with the other bending portions 150 of the first pole piece 110, the innermost bending portion 150 of the first pole piece 110 has a larger curvature and is subjected to greater stress. Therefore, the phenomenon of active material shedding in the innermost bending portion 150 of the first pole piece 110 is more serious and is more prone to burrs. Similarly, compared with the other bending portions 150 of the second pole piece 120, the innermost bending portion 150 of the second pole piece 120 has a larger curvature and is subjected to greater stress. Therefore, the phenomenon of active material shedding in the innermost bending portion 150 of the second pole piece 120 is more serious and is more prone to burrs.

[0116] This embodiment can set the second separator 132 in the area where the lithium plating problem is serious, thereby effectively reducing the short circuit problem of the electrode assembly 100 caused by the damage of the separator, and improving the service life and safety of the electrode assembly 100.

[0117] In some embodiments, a plurality of second spacers 132 are provided in the bending region B, and adjacent second spacers 132 are separated by the first pole piece 110 or the second pole piece 120. Among adjacent second spacers 132, the thickness of the inner second spacer 132 is greater than the thickness of the outer second spacer 132.

[0118] In the bending area B, the curvature of the bending portion 150 gradually decreases from the inside to the outside, and the stress on the bending portion 150 also gradually decreases; that is, in the bending area B, the lithium deposition problem occurring in the inner bending portion 150 is more serious than the lithium deposition problem occurring in the outer bending portion 150.

[0119] In this embodiment, the inner second isolation member 132 has a greater thickness to minimize the risk of puncture; the outer second isolation member 132 has a low risk of puncture, so it can have a smaller thickness to save the use of the second isolation member 132 and improve the energy density of the electrode assembly 100.

[0120] In some embodiments, the plurality of second isolation members 132 are independently provided, and the position of each second isolation member 132 can be freely set as needed.

[0121] In some embodiments, the electrode assembly 100 further includes a straight region C connected to the bent region B, and both ends of the second separator 132 along the winding direction X are located in the straight region C.

[0122] The straight region C is a region of the electrode assembly 100 having a straight structure. The first electrode piece 110 and the second electrode piece 120 both include a plurality of straight portions 160 located in the straight region C. The straight portions 160 in the straight region C are substantially straight. For example, the straight portions 160 are generally flat.

[0123] Exemplarily, there are two bending regions B, which are respectively connected to the two ends of the straight region C. At least one bending region B is provided with a second isolating member 132 ; optionally, both bending regions B are provided with a second isolating member 132 .

[0124] In this embodiment, the second isolation member 132 can completely separate the first pole piece 110 from the second pole piece 120 to improve safety.

[0125] In some embodiments, the second spacer 132 is attached to an outer surface of the first spacer 131 .

[0126] The second separator 132 may be entirely attached to the first separator 131 or only partially attached to the first separator 131. For example, both ends of the second separator 132 along the winding direction X are attached to the first separator 131.

[0127] In this embodiment, the second isolating member 132 is attached to the first isolating member 131, which can reduce the risk of the second isolating member 132 being offset or misplaced along the winding direction X during charging and discharging, ensure the protective effect of the second isolating member 132 in the bending area B, and improve safety.

[0128] When the first separator 131 is bent, its inner surface compresses and its outer surface stretches. If the second separator 132 is attached to the inner surface of the first separator 131, the second separator 132 may wrinkle under the influence of the first separator 131, affecting ion transmission. In this embodiment, the second separator 132 is attached to the outer surface of the first separator 131. The second separator 132 is stretched under the influence of the first separator 131, which can reduce the risk of wrinkling of the second separator 132.

[0129] In this application, the terms "inside" and "outside" are relative to the winding center of the electrode assembly 100. The side facing the winding center is the inside, and the side facing away from the winding center is the outside. In other words, the surface of the first separator 131 facing the winding center is the inside surface, and the surface facing away from the winding center is the outside surface.

[0130] In some embodiments, the second spacer 132 is bonded to the outer surface of the first spacer 131 by heat and pressure bonding.

[0131] In some embodiments, the first spacer 131 and the second spacer 132 may be made of PP (polypropylene) or PE (polyethylene). This configuration allows for more convenient processing and lower costs, which is beneficial for commercialization.

[0132] In some embodiments, the first separator 131 may be PP (polypropylene) or PE (polyethylene), and the second separator 132 may be one of a polypropylene / ultra-high molecular weight polyethylene membrane / epoxy resin composite membrane, a porous poly-separation membrane, a coaxial composite nanofiber membrane, a porous membrane, a glass fiber battery membrane, and a PVDF-HFP polymer electrolyte membrane. Among them, the polypropylene / ultra-high molecular weight polyethylene membrane / epoxy resin composite membrane can improve the porosity and heat resistance of the membrane. The porous poly-separation membrane can have both air permeability and puncture strength. The coaxial composite nanofiber membrane is composed of composite nanofibers with a fluorine-containing skin layer and a polyimide core layer, which can not only ensure excellent wettability, liquid retention and ion conductivity, but also has high mechanical strength and heat resistance. The porous membrane is prepared by mixing polyolefin with silica or other inorganic substances. The glass fiber battery separator is composed of alkali-free glass fiber, PET (polyester), and PA (polyamide). Through this configuration, the second separator 132 has greater puncture resistance and mechanical strength, and has a stronger inhibitory effect on lithium dendrites.

[0133] In some embodiments, the second isolation member 132 includes a plurality of isolation layers 1321 stacked along a thickness direction of the second isolation member 132 .

[0134] In this embodiment, the multi-layer structure can improve the strength of the second isolation member 132, increase the difficulty of puncturing the second isolation member 132, and improve safety.

[0135] In some embodiments, adjacent isolation layers 1321 are bonded to each other.

[0136] exist Figure 4 and Figure 5 In the figure, the isolation layers 1321 are represented by lines; although there are gaps between the isolation layers 1321 in the figure, in fact, adjacent isolation layers 1321 can be bonded together.

[0137] In this embodiment, multiple isolation layers 1321 are bonded together, which can reduce the risk of offset between the multiple isolation layers 1321 during the winding process of the electrode assembly 100 and ensure the protective effect of the second isolation member 132 in the bending area B.

[0138] In some embodiments, the plurality of isolation layers 1321 may be bonded together by heat and pressure.

[0139] In some embodiments, the material of the isolation layer 1321 is the same as that of the first isolation member 131 , and the thickness of the isolation layer 1321 is equal to the thickness of the first isolation member 131 .

[0140] In this embodiment, the first isolation member 131 and the second isolation member 132 may be made of isolation members of the same specifications, which can simplify the process and reduce costs.

[0141] Figure 6 Schematic diagram of the partial structure of the electrode assembly provided in some other embodiments of the present application.

[0142] like Figure 6 As shown, in some embodiments, the plurality of isolation layers include a first isolation layer 132a and a second isolation layer 132b disposed adjacent to each other, and the first isolation layer 132a is located between the second isolation layer 132b and the first isolation member 131. In the winding direction X, the end of the second isolation layer 132b is offset from the end of the first isolation layer 132a.

[0143] The staggered arrangement means that the end portion of the second isolation layer 132 b does not overlap with the end portion of the first isolation layer 132 a in the thickness direction of the second isolation member 132 .

[0144] Illustratively, two isolation layers among the plurality of isolation layers are respectively a first isolation layer 132 a and a second isolation layer 132 b .

[0145] The first isolation layer 132a has two ends along the winding direction X, defined as a first end and a second end, and the second isolation layer 132b has two ends along the winding direction X, defined as a third end and a fourth end. The third end is closer to the first end than the fourth end, and the fourth end is closer to the second end than the third end.

[0146] In this embodiment, the first end and the third end are staggered along the winding direction X. The second end and the fourth end can be aligned along the winding direction X, or staggered along the winding direction X.

[0147] During the charge and discharge process, the first electrode sheet 110 and the second electrode sheet 120 expand and squeeze the first and second isolation layers 132a, 132b. If the ends of the first and second isolation layers 132a, 132b are aligned, they will squeeze the same location of the electrode sheet, causing stress concentration and affecting the performance of the electrode sheet.

[0148] In this embodiment, the end of the second isolation layer 132b is staggered with the end of the first isolation layer 132a, so that the end of the second isolation layer 132b and the end of the first isolation layer 132a can squeeze different areas of the pole piece, reduce stress concentration, reduce the risk of pole piece cracking, and improve the performance of the pole piece.

[0149] In some embodiments, in the winding direction X, both ends of the second isolation layer 132 b extend beyond the first isolation layer 132 a and are attached to the first isolation member 131 .

[0150] The first isolation layer 132 a may be independently disposed between the second isolation layer 132 b and the first isolation member 131 , or may be attached to the second isolation layer 132 b or the first isolation member 131 .

[0151] In this embodiment, the second isolation layer 132b is attached to the first isolation member 131 and can limit the movement of the first isolation layer 132a in the winding direction X. This can reduce the risk of the first isolation layer 132a and the second isolation layer 132b being offset or misaligned along the winding direction X during the charging and discharging process, ensure the protective effect of the second isolation member 132 in the bending area B, and improve safety.

[0152] In some embodiments, the first isolation layer 132 a is attached to the first isolation member 131 .

[0153] The first isolation layer 132a may be entirely attached to the first isolation member 131 or only partially attached to the first isolation member 131. For example, both ends of the first isolation layer 132a along the winding direction X are attached to the first isolation member 131.

[0154] This embodiment can reduce the risk of the first isolation layer 132a being offset or misplaced along the winding direction X, ensure the protective effect of the first isolation layer 132a in the bending area B, and improve safety.

[0155] Figure 7 Schematic diagram of the partial structure of the electrode assembly provided in some other embodiments of the present application.

[0156] like Figure 7As shown, in some embodiments, the electrode assembly 100 further includes a straight region C connected to the bent region B. The first isolation layer 132a is entirely located in the bent region B. Both ends of the second isolation layer 132b along the winding direction X are located in the straight region C.

[0157] In this embodiment, the first and second isolation layers 132a, 132b, can simultaneously provide protection in the bend region B, reducing the risk of short circuits and improving safety. The entire first isolation layer 132a is located in the bend region B, preventing it from interfering with ion transport in the straight region C and ensuring charge and discharge performance in the straight region C. The two ends of the second isolation layer 132b, along the winding direction X, are located in the straight region C, allowing the ends of the second isolation layer 132b to be offset from the ends of the first isolation layer 132a, reducing stress concentration.

[0158] In some embodiments, an end portion of the first isolation layer 132a along the winding direction X is located at a junction of the straight region C and the bent region B.

[0159] Figure 8 Schematic diagram of the partial structure of the electrode assembly provided in some further embodiments of the present application.

[0160] like Figure 8 As shown, the second electrode sheet 120 is a negative electrode sheet, and the second separator 132 is attached to the outer surface of the second electrode sheet 120 .

[0161] In this embodiment, the second isolation member 132 is attached to the outer surface of the second pole piece 120 . The second isolation member 132 is stretched under the action of the second pole piece 120 , which can reduce the risk of wrinkling of the second isolation member 132 .

[0162] In bend region B, the diameter of the positive electrode sheet outside the negative electrode sheet is larger than that of the negative electrode sheet. Therefore, the area of ​​the positive active material layer of the positive electrode sheet outside the negative electrode sheet is larger than that of the negative active material layer of the negative electrode sheet. This makes lithium deposition more likely on the outer surface of the negative electrode sheet. In this embodiment, the second separator 132 is attached to the outer surface of the negative electrode sheet to reduce the risk of short circuits and improve safety.

[0163] Figure 9 A schematic flow chart of a method for manufacturing a battery assembly provided in some embodiments of the present application.

[0164] like Figure 9 As shown, the manufacturing method of the battery assembly of the embodiment of the present application includes:

[0165] S100, providing a first pole piece, a second pole piece, a first separator and a second separator;

[0166] S200, winding the first pole piece, the second pole piece and the first separator along a winding direction to form a bending region;

[0167] Among them, the polarities of the first pole piece and the second pole piece are opposite, and the first isolating member is used to separate the first pole piece and the second pole piece; a second isolating member is provided in the bending area, and the second isolating member is stacked with the first isolating member and is used to separate the adjacent first pole piece and the second pole piece; at least part of the ions escaped from the first pole piece can pass through the first isolating member and the second isolating member and be embedded in the second pole piece.

[0168] It should be noted that the relevant structure of the battery assembly manufactured by the above-mentioned battery assembly manufacturing method can refer to the battery assembly provided in the above-mentioned embodiments.

[0169] Figure 10 A schematic block diagram of a manufacturing system for an electrode assembly provided in some embodiments of the present application.

[0170] like Figure 10 As shown, the manufacturing system 90 of the battery assembly of the embodiment of the present application includes a providing device 91 and a winding device 92. The providing device 91 is used to provide a first pole piece, a second pole piece, a first separator and a second separator. The winding device 92 is used to wind the first pole piece, the second pole piece and the first separator along the winding direction to form a bending area. The polarity of the first pole piece and the second pole piece are opposite, and the first separator is used to separate the first pole piece and the second pole piece; a second separator is provided in the bending area, and the second separator is stacked with the first separator and is used to separate the adjacent first pole piece and the second pole piece; at least part of the ions released from the first pole piece can pass through the first separator and the second separator and be embedded in the second pole piece.

[0171] The relevant structure of the electrode assembly manufactured by the above-mentioned manufacturing system can refer to the electrode assemblies provided in the above-mentioned embodiments.

[0172] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0173] 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An electrode assembly comprising a first electrode sheet, a second electrode sheet, and a first separator, wherein the first electrode sheet and the second electrode sheet have opposite polarities, the first separator is used to separate the first electrode sheet and the second electrode sheet, and the first electrode sheet, the second electrode sheet, and the first separator are wound along a winding direction; in, The electrode assembly has a bending region, wherein a second separator is provided in the bending region. The second separator is stacked with the first separator and is used to separate the adjacent first electrode piece and the second electrode piece; at least part of the ions released from the first electrode piece can pass through the first separator and the second separator and be embedded in the second electrode piece; The second isolation member includes a plurality of isolation layers stacked along a thickness direction of the second isolation member. The isolation layers are made of the same material as the first isolation member, and have a thickness equal to that of the first isolation member.

2. The electrode assembly according to claim 1, wherein Adjacent isolation layers are bonded to each other.

3. The electrode assembly according to claim 1 or 2, wherein: The plurality of isolation layers include a first isolation layer and a second isolation layer disposed adjacent to each other, the first isolation layer being located between the second isolation layer and the first isolation member; In the winding direction, the end portion of the second isolation layer is staggered with the end portion of the first isolation layer.

4. The electrode assembly according to claim 3, wherein: In the winding direction, both ends of the second insulating layer extend beyond the first insulating layer and are attached to the first insulating member.

5. The electrode assembly according to claim 4, wherein The electrode assembly further includes a straight region connected to the bent region; The first isolation layer is entirely located in the bending area; and both ends of the second isolation layer along the winding direction are located in the straight area.

6. The electrode assembly according to claim 3, wherein: The first isolation layer is attached to the first isolation member.

7. The electrode assembly according to claim 1 or 2, wherein: The porosity of the second separator is greater than or equal to the porosity of the first separator.

8. The electrode assembly according to claim 1 or 2, wherein: In the bending region, the second isolating member is provided between at least the innermost adjacent first pole piece and the second pole piece.

9. The electrode assembly according to claim 1 or 2, wherein: The bending region is provided with a plurality of second isolating members, and adjacent second isolating members are separated by the first pole piece or the second pole piece; Among adjacent second spacers, the thickness of the inner second spacer is greater than the thickness of the outer second spacer.

10. The electrode assembly according to claim 1 or 2, wherein: The electrode assembly further includes a straight region connected to the bent region, and both ends of the second separator along the winding direction are located in the straight region.

11. The electrode assembly according to claim 1 or 2, wherein: The second spacer is attached to an outer surface of the first spacer.

12. The electrode assembly according to claim 1 or 2, wherein: The second pole piece is a negative pole piece, and the second separator is attached to the outer surface of the second pole piece.

13. A battery cell comprising: shell; The electrode assembly according to any one of claims 1 to 12, housed in the housing. 14 . A battery comprising a plurality of battery cells according to claim 13 . 15 . An electrical device comprising the battery cell according to claim 13 , wherein the battery cell is used to provide electrical energy.

16. A method for manufacturing a battery assembly, comprising: Providing a first pole piece, a second pole piece, a first separator and a second separator; Winding the first pole piece, the second pole piece, and the first separator along a winding direction to form a bending area; The first pole piece and the second pole piece have opposite polarities, and the first separator is used to separate the first pole piece and the second pole piece; the bending region is provided with a second separator, and the second separator is stacked with the first separator and is used to separate the adjacent first pole piece and the second pole piece; at least part of the ions released from the first pole piece can pass through the first separator and the second separator and be embedded in the second pole piece; The second isolation member includes a plurality of isolation layers stacked along a thickness direction of the second isolation member. The isolation layers are made of the same material as the first isolation member, and have a thickness equal to that of the first isolation member.

17. A battery assembly manufacturing system comprising: Providing an apparatus for providing a first pole piece, a second pole piece, a first spacer, and a second spacer; a winding device, configured to wind the first pole piece, the second pole piece, and the first separator along a winding direction to form a bending region; The first pole piece and the second pole piece have opposite polarities, and the first separator is used to separate the first pole piece and the second pole piece; the bending region is provided with a second separator, and the second separator is stacked with the first separator and is used to separate the adjacent first pole piece and the second pole piece; at least part of the ions released from the first pole piece can pass through the first separator and the second separator and be embedded in the second pole piece; The second isolation member includes a plurality of isolation layers stacked along a thickness direction of the second isolation member. The isolation layers are made of the same material as the first isolation member, and have a thickness equal to that of the first isolation member.

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