Battery monomer, battery device and electric equipment

Abstract

The utility model discloses a battery monomer, a battery device and electric equipment. The battery monomer comprises a shell and an electrode assembly, wherein the electrode assembly comprises a first pole piece and a second pole piece which have opposite polarities and are laminated. The first pole piece comprises a first current collector and a first film layer, the first current collector comprises a first coating area and a first tab which are arranged along a first direction, the first film layer is arranged in the first coating area, and the first tab is not provided with the first film layer. The second pole piece comprises a second current collector and a second film layer, the second current collector comprises a second coating area and a blank area which are arranged along the first direction, the second film layer is arranged in the second coating area, and the blank area is not provided with the second film layer; the electrode assembly further comprises a liquid retaining layer capable of absorbing electrolyte, and at least part of the liquid retaining layer is arranged in the blank area and located between the first film layer and the blank area. The liquid retaining layer exceeds the first coating area in the direction from the second coating area to the blank area. And the electrolyte retention layer can supplement electrolyte, so that the cycle performance of the battery monomer can be maintained or improved.

Description

Technical Field

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

[0002] With the development of new energy technologies, batteries are becoming increasingly widely used. For example, batteries are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but are also widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace, among other fields.

[0003] The development of battery technology must take into account multiple design factors at the same time, such as energy density, assembly efficiency, processing technology, etc., as well as the battery's cycle performance and reliability. Utility Model Content

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

[0005] According to a first aspect of the present application, a battery cell is provided, comprising a housing and an electrode assembly housed within the housing, the electrode assembly comprising a first electrode sheet and a second electrode sheet of opposite polarity, the first electrode sheet and the second electrode sheet being stacked. The first electrode sheet comprises a first current collector and a first film layer, the first current collector comprising a first coating region and a first tab arranged along a first direction, the first film layer being arranged in the first coating region, the first tab being not provided with the first film layer, and the first direction being perpendicular to the thickness direction of the first electrode sheet; the second electrode sheet comprises a second current collector and a second film layer, the second current collector comprising a second coating region and a blank region arranged along the first direction, the second film layer being arranged in the second coating region, the blank region being not provided with the second film layer; the electrode assembly further comprises a liquid retention layer, the liquid retention layer being capable of absorbing electrolyte, at least a portion of the liquid retention layer being arranged in the blank region and between the first film layer and the blank region; the liquid retention layer extending beyond the first coating region in a direction from the second coating region to the blank region. The liquid retention layer can absorb a certain amount of electrolyte, thereby being in a high liquid retention state. During the charge and discharge process of the battery cell, the first film layer expands, compressing the gap between the first and second pole pieces. The liquid-retention layer, which is in a high-liquid-retention state, is squeezed, releasing some electrolyte, thereby replenishing electrolyte for the electrochemical reaction of the battery cell and helping to maintain or improve the battery cell's cycle performance. Furthermore, the liquid-retention layer can also cover at least a portion of the cut edge of the first pole piece, thereby shielding burrs or metal particles on the edge of the first coating area, providing insulation and isolation, reducing the risk of conduction between the first and second pole pieces and improving the reliability of the battery cell.

[0006] In some embodiments, the blank area includes a transition area arranged along the first direction and a second tab, the transition area is connected to the second coating area, the second tab is arranged on a side of the transition area away from the second coating area, and at least part of the liquid retaining layer is connected to the transition area. Since the transition area is not provided with the second film layer, the surface thereof is relatively smooth, the connection strength and stability between the liquid retaining layer and the transition area can be improved, and the risk of the liquid retaining layer falling off can be reduced. The liquid retaining layer at least partially covers the transition area, the risk of the blank area being short-circuited with the first tab is reduced, and meanwhile, a proper amount of electrolyte can be maintained on the surface of the transition area, the side reaction between the electrolyte and the transition area is reduced, and the risk of leakage during high-voltage test of the battery cell is reduced.

[0007] In some embodiments, along a direction in which the second coating area points to the blank area, the first film layer exceeds the first end surface of the second film layer facing the blank area, and along the thickness direction, the projection of the transition area and the projection of the first film layer at least partially overlap. In this way, the overlapping area of the liquid retaining layer and the second film layer along the thickness direction of the first tab can be increased, so that the area of the liquid retaining layer that can receive the extrusion effect is increased, which is beneficial to increase the compression deformation amount of the liquid retaining layer and increase the amount of electrolyte released by the liquid retaining layer.

[0008] In some embodiments, along the thickness direction, the liquid retaining layer completely covers the transition area, which further reduces the risk of the blank area being short-circuited with the first tab, and meanwhile, a balanced amount of electrolyte can be maintained on the surface of the transition area, which further reduces the side reaction between the electrolyte and the transition area and the risk of leakage during high-voltage test of the battery cell.

[0009] In some embodiments, at least part of the liquid retaining layer is bonded to the transition area. In this way, the connection strength of the liquid retaining layer and the blank area can be improved, and the risk of the liquid retaining layer falling off can be reduced. Moreover, the structure of the liquid retaining layer is relatively stable, which is beneficial to reduce the possibility of adversely affecting the second tab, the position of the liquid retaining layer relative to the second tab can be easily controlled during assembly, the liquid retaining layer can be bonded to the second tab during cutting of the second tab, and the assembly efficiency is relatively high.

[0010] In some embodiments, along a direction in which the blank area points to the second coating area, the liquid retaining layer exceeds the first end surface of the second film layer facing the blank area. The liquid retaining layer can completely cover the interface between the second coating area and the transition area, the possibility of the side of the transition area close to the second coating area being exposed is reduced, and the risk of the transition area being short-circuited with the first tab is reduced.

[0011] In some embodiments, the second film layer comprises a main body region and a thinning region arranged along the first direction, the thinning region is connected to the main body region and located on a side of the main body region facing the blank region, the thickness of the main body region is greater than the thickness of the thinning region; along the thickness direction, the liquid retaining layer covers at least part of the thinning region, and the projection of the liquid retaining layer and the projection of the main body region are separated. The liquid retaining layer and the main body region do not have thickness superposition. The liquid retaining layer and the thinning region have thickness superposition, the thickness of the thinning region is thinner, a part of the liquid retaining layer can be accommodated in the thinning space of the thinning region, the space utilization rate is improved, the total thickness of the liquid retaining layer and the thinning region after superposition is reduced, the space is saved, and the possibility of edge bulging of the electrode assembly is reduced.

[0012] In some embodiments, along the direction from the blank region to the second coating region, the size of the liquid retaining layer beyond the first end surface is 0.5mm-3mm. In this way, it is not only conducive to improving the effect of the liquid retaining layer covering the transition region and the connection stability between the liquid retaining layer and the transition region, but also conducive to reducing the adverse effect on the capacity of the battery monomer.

[0013] In some embodiments, along the direction from the second coating region to the blank region, the liquid retaining layer exceeds the second end surface facing the second tab of the transition region. The liquid retaining layer can completely cover the second end surface, reduce the possibility of the side of the transition region close to the second tab being exposed, and reduce the risk of the transition region being short-circuited with the first tab. More importantly, the liquid retaining layer can also cover at least part of the cutting edge of the second tab, thereby shielding burrs or metal particles of the second end surface, and having an insulating isolation effect, which is conducive to further reducing the risk of the first tab and the second tab being conductive and improving the reliability of the battery monomer.

[0014] In some embodiments, along the direction from the second coating region to the blank region, the size of the liquid retaining layer beyond the second end surface is 1mm-5mm. In this way, it is not only possible to improve the effect of the liquid retaining layer shielding the burrs, but also conducive to reducing the possibility of interference with the first tab and / or the second tab.

[0015] In some embodiments, the second end surface comprises a tab leading-out region and a non-tab leading-out region, the second tab only extends out from the tab leading-out region and protrudes from the liquid retaining layer in a direction away from the transition region; the liquid retaining layer comprises a first liquid retaining part and a second liquid retaining part, at least part of the first liquid retaining part is arranged in the transition region, the second liquid retaining part comprises a first extension part and a second extension part, the first extension part is arranged outside the non-tab leading-out region along the first direction, and the second extension part is arranged outside the tab leading-out region along the first direction and covers part of the second tab along the thickness direction. The first extension part can shield burrs or metal particles on the non-tab leading-out region. The second extension part can cover the root of the second tab close to the transition region, shield the burrs of the root of the second tab, and reduce the risk of the root of the second tab being torn open. At the same time, it can also reduce the risk of the second tab being inserted between the first tab and the second tab when being bent.

[0016] In some embodiments, the first coating region has two first surfaces disposed opposite each other along the thickness direction. The first electrode includes two first film layers, one disposed on each of the first surfaces. The second electrode has at least one liquid-retaining layer disposed on each side of the second electrode along the thickness direction. When the first film layers of the two first electrode sheets on either side of the second electrode sheet expand along the thickness direction of the first electrode sheet, they can squeeze the two liquid-retaining layers of the second electrode sheet. Both liquid-retaining layers can release electrolyte, thereby improving the electrolyte replenishment capability and further enhancing the cycling performance of the battery cell.

[0017] In some embodiments, along the direction from the second coating area to the blank area, at least the portion of the liquid-retention layer on either side of the second electrode plate that extends beyond the second end surface is bonded together. This improves the connection strength between the liquid-retention layer and the second electrode plate, reducing the risk of the liquid-retention layer falling off. The liquid-retention layer can cover the second end surface, and the bonded portion has relatively high structural strength, making it less susceptible to puncture by burrs, thereby effectively shielding burrs.

[0018] In some embodiments, the liquid-retaining layer does not extend beyond the second surface of the second film layer facing away from the second coating region, along the direction from the second coating region toward the second film layer. The provision of the liquid-retaining layer does not increase the thickness of the edge of the second electrode sheet, thereby reducing the possibility of bulging at the edge of the electrode assembly.

[0019] In some embodiments, the maximum thickness of the liquid-retaining layer is less than the maximum thickness of the second film layer. Along the direction from the second coating region to the second film layer, the second film layer may extend beyond the surface of the liquid-retaining layer facing away from the second coating region, thereby reducing the overall thickness of the second electrode sheet edge and minimizing the possibility of bulging at the edge of the electrode assembly.

[0020] In some embodiments, the electrode assembly further includes a separator disposed between the first and second electrode sheets. The first film layer has an expansion coefficient of K, a maximum thickness of the portion of the first film layer overlapping the liquid-retaining layer along the thickness direction is D1, a minimum separation distance between the first film layer and the liquid-retaining layer along the thickness direction is L, and a thickness of the separator is D2. K, D1, L, and D2 satisfy the following: K × D1 > L - D2. After the first film layer expands, the portion of the first film layer overlapping the liquid-retaining layer along the thickness direction and having the greatest thickness can contact and squeeze the liquid-retaining layer, enabling the liquid-retaining layer to more effectively release electrolyte.

[0021] In some embodiments, the first electrode is a negative electrode, the second electrode is a positive electrode, and the first film layer comprises a silicon-based material. During the charge and discharge process of the battery cell, the volume of the silicon-based material expands significantly. The first film layer comprising the silicon-based material can more effectively squeeze the liquid-retaining layer on the second electrode through expansion, thereby more effectively replenishing the electrolyte.

[0022] According to a second aspect of the present application, an embodiment of the present application provides a battery device, which includes a plurality of battery cells provided according to any embodiment of the present application.

[0023] According to a third aspect of the present application, an embodiment of the present application provides an electrical device, which includes a battery device provided according to any embodiment of the present application, and the battery device is used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces 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 these drawings without creative work.

[0025] Figure 1 It is a schematic structural diagram of a vehicle provided in some embodiments of the present application.

[0026] Figure 2 It is a schematic diagram of the exploded structure of the battery device provided in some embodiments of the present application.

[0027] Figure 3 This is a schematic diagram of the exploded structure of a battery cell provided in some embodiments of the present application.

[0028] Figure 4 Schematic top view of an electrode assembly of a battery cell provided in some embodiments of the present application.

[0029] Figure 5 for Figure 4 Schematic diagram of a local section taken along the AA direction.

[0030] Figure 6 This is a schematic structural diagram of the second pole piece and liquid retention layer of the battery cell provided in some embodiments of the present application after being flattened.

[0031] Figure 7 yes Figure 6 Schematic diagram of the cross-sectional structure along the BB direction.

[0032] Figure 8 yes Figure 6 Schematic diagram of the cross-sectional structure along the CC direction.

[0033] In the attached figure:

[0034] Vehicle 1, battery device 2, controller 3, motor 4, box 5, battery cell 6;

[0035] Electrode assembly 10, first pole piece 11, first current collector 111, first film layer 112, thinning area 1122, first coating area 113, first surface 1131, third end face 1132, first pole ear 114, second pole piece 12, second current collector 121, second film layer 122, main body area 1221, thinning area 1222, second surface 1223, first end face 122a, second coating area 123, third surface 1231, blank area 124, transition area 125, second End face 1251, tab lead-out area 1251a, non-tab lead-out area 1251b, second tab 126, liquid retaining layer 13, first liquid retaining portion 131, second liquid retaining portion 132, first extension portion 1321, second extension portion 1322, liquid absorption layer 13a, glue layer 13b, spacer 14, outer shell 20, shell 21, end cover 22, electrode terminal 30, first box body portion 5a, second box body portion 5b, dimension d1, dimension d2, first direction X, thickness direction Y, second direction Z. DETAILED DESCRIPTION

[0036] 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 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.

[0037] Unless otherwise defined, all technical and scientific terms used in this application 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 this 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" and "second" 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.

[0038] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the 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.

[0039] 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.

[0040] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0041] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0042] The term "plurality" used in this application refers to two or more (including two).

[0043] In the embodiments of the present application, "parallel" includes not only the absolutely parallel situation, but also the roughly parallel situation conventionally recognized in engineering; at the same time, "vertical" includes not only the absolutely vertical situation, but also the roughly vertical situation conventionally recognized in engineering.

[0044] In the embodiment of the present application, the battery cell may be a secondary battery cell. A secondary battery cell refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0045] A battery cell typically includes an electrode assembly, which includes a positive electrode sheet and a negative electrode sheet. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are inserted and removed between the positive and negative electrodes. For example, the electrode assembly also includes a separator disposed between the positive and negative electrode sheets. The separator prevents short circuits between the positive and negative electrode sheets while allowing active ions to pass through.

[0046] The battery cell can be a lithium-ion battery cell, a sodium-ion battery cell, a sodium-lithium-ion battery cell, a lithium metal battery cell, a sodium metal battery cell, a lithium-sulfur battery cell, a magnesium-ion battery cell, a nickel-hydrogen battery cell, a nickel-cadmium battery cell, a lead-acid battery cell, etc., and the embodiments of the present application are not limited to this.

[0047] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, or a battery cell of other shapes, including a square battery cell, a blade battery cell, a multi-prismatic battery cell, such as a hexagonal battery cell, and the like, without particular limitation.

[0048] The battery cell can be a hard-shell battery cell, a pouch battery cell, or other types of battery cells.

[0049] The battery device mentioned in embodiments of the present application can include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly can include a plurality of battery cells connected in series, in parallel, or in a mixed connection through a busbar component.

[0050] In some embodiments, the battery cell assembly is generally formed by arranging a plurality of battery cells. The battery device generally includes a box for packaging one or more battery cells. The box can prevent liquid or other foreign matter from affecting the charging or discharging of the battery cell.

[0051] As an example, the battery cell assembly can be a battery module formed by arranging and fixing a plurality of battery cells into an independent module. As an example, the battery module can be formed by bundling a plurality of battery cells with a cable tie. The battery cell assembly can be accommodated in the box by fixing the battery module in the box.

[0052] As an example, the box can include a top cover, a frame, and a bottom plate. The top cover and the bottom plate are respectively connected with the frame, so that a closed space is formed inside the box to accommodate the battery cell assembly.

[0053] In some embodiments, the box can be part of the chassis structure of the vehicle. For example, part of the box can be at least part of the floor of the vehicle, or part of the box can be at least part of the cross beam and the longitudinal beam of the vehicle.

[0054] In some embodiments, the battery device can be an energy storage device. The energy storage device includes an energy storage container, an energy storage cabinet, and the like.

[0055] The battery cell generally includes an electrode assembly and a housing, and the electrode assembly is accommodated in the housing. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charging and discharging of the battery cell, active ions (such as lithium ions) are embedded and extracted between the positive electrode and the negative electrode. The separator is arranged between the positive electrode and the negative electrode, which can reduce the risk of short circuit of the positive and negative electrodes, and at the same time allow the active ions to pass through.

[0056] The housing is used to package the electrode assembly and other components such as electrolyte. The housing can be a steel shell, an aluminum shell, a plastic shell (such as polypropylene), a composite metal shell (such as a copper-aluminum composite shell), or an aluminum-plastic film, and the like.

[0057] In some embodiments, the positive electrode may be a positive electrode sheet, which may include a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector. The negative electrode may be a negative electrode sheet, which may include a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector.

[0058] Silicon-based materials have been successfully used as battery anode materials due to their ultra-high specific capacity. However, silicon undergoes significant volume expansion during the charge and discharge process, leading to rupture of the SEI (solid electrolyte interface) film and material pulverization. The exposed surface of the anode material comes into contact with the electrolyte and reacts, forming a new SEI film. This process continuously consumes electrolyte and reduces the cycle performance of the battery cells.

[0059] In order to solve the above problems, one feasible solution is to improve the material structure, such as through nano-sizing, core-shell structure, etc., to maintain the structural integrity of the material for as long as possible and reduce the consumption of electrolyte. However, nano-sizing will reduce the initial effect, the core-shell structure will lose energy density, and from a long-term perspective, the electrolyte will also be continuously consumed. Another feasible solution is to develop a new adhesive to confine the silicon-based negative electrode through the adhesive to achieve the effect of inhibiting volume expansion. However, due to the limitations of the development progress of new adhesives, this solution cannot achieve the expected effect of improving the performance of silicon-based negative electrodes.

[0060] The applicant's analysis revealed that volume expansion is inevitable for silicon-based negative electrodes, and the ultimate failure mode is repeated volume expansion leading to structural collapse of the material and consumption of electrolyte by the fresh material surface. Therefore, considering how to replenish the battery cell during the continuous electrolyte consumption process is crucial.

[0061] In view of this, the present invention provides a technical solution that disposes a liquid-retaining layer between two electrode pieces. The liquid-retaining layer absorbs a certain amount of electrolyte. When the electrode piece expands, it squeezes the highly liquid-retaining layer, prompting it to release some electrolyte. This replenishes electrolyte for the electrochemical reaction of the battery cell, helping to maintain or improve the cycle performance of the battery cell. Furthermore, the liquid-retaining layer covers the cut edges of the electrode piece, shielding burrs and reducing the risk of conduction between the two electrode pieces, thereby improving the reliability of the battery cell.

[0062] The technical solutions provided in the embodiments of the present application are applicable to battery cells, battery devices, and electrical equipment using the battery devices.

[0063] The battery device disclosed in the embodiments of the present application can be used in various energy storage systems that use the battery device as a power source or use the battery device as an energy storage element. The power-consuming device can be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, and the like. Among them, the electric toy can include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, and the like, and the spacecraft can include an airplane, a rocket, a space shuttle, and a spacecraft, and the like.

[0064] For the convenience of description, the following embodiments are described by taking the electric device as a vehicle as an example.

[0065] Figure 1 Schematic diagram of the structure of the vehicle provided by some embodiments of the present application. Figure 1 Vehicle 1 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, or an extended-range vehicle. A battery device 2 is provided inside vehicle 1. Battery device 2 can be located at the bottom, head, or tail of vehicle 1. Battery device 2 can be used to power vehicle 1. For example, battery device 2 can serve as an operating power source for vehicle 1. Vehicle 1 can also include a controller 3 and a motor 4. Controller 3 is used to control battery device 2 to power motor 4, for example, to meet the power requirements of vehicle 1 during startup, navigation, and driving.

[0066] In some embodiments of the present application, the battery device 2 can serve not only as an operating power source for the vehicle 1 , but also as a driving power source for the vehicle 1 , replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1 .

[0067] Figure 2 Schematic diagram of the exploded structure of the battery device provided in some embodiments of the present application. Figure 2The battery device 2 includes a housing 5 and a battery cell 6, and the battery cell 6 is accommodated in the housing 5. The housing 5 is used to provide a storage space for the battery cell 6, and the housing 5 can adopt a variety of structures. In some embodiments, the housing 5 can include a first housing portion 5a and a second housing portion 5b, and the first housing portion 5a and the second housing portion 5b cover each other, and the first housing portion 5a and the second housing portion 5b jointly define a storage space for accommodating the battery cell 6. The second housing portion 5b can be a hollow structure with one end open, and the first housing portion 5a can be a plate-shaped structure, and the first housing portion 5a covers the open side of the second housing portion 5b, so that the first housing portion 5a and the second housing portion 5b jointly define a storage space; the first housing portion 5a and the second housing portion 5b can also be hollow structures with one side open, and the open side of the first housing portion 5a covers the open side of the second housing portion 5b. Of course, the box body 5 formed by the first box body portion 5a and the second box body portion 5b can be in various shapes, such as a cylinder, a rectangular parallelepiped, etc.

[0068] In order to improve the sealing performance after the first box body 5a and the second box body 5b are connected, a sealing member, such as a sealant, a sealing ring, etc., may also be provided between the first box body 5a and the second box body 5b.

[0069] Assuming that the first box body portion 5a covers the top of the second box body portion 5b, the first box body portion 5a can also be called an upper box cover, and the second box body portion 5b can also be called a lower box body.

[0070] In the battery device 2, there may be multiple battery cells 6, which may 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 battery cells 6. Multiple battery cells 6 may be directly connected in series, in parallel, or in a hybrid configuration, and then the entire battery unit 6 is housed within the housing 5. Alternatively, the battery device 2 may comprise multiple battery cells 6 that are first connected in series, in parallel, or in a hybrid configuration to form a battery module, which is then further connected in series, in parallel, or in a hybrid configuration to form a single unit housed within the housing 5. The battery device 2 may also include other structures, such as a busbar assembly for electrically connecting the multiple battery cells 6.

[0071] For example, the battery cell 6 may be the smallest unit constituting the battery device 2 .

[0072] Figure 3 Schematic diagram of the exploded structure of the battery cell provided in some embodiments of the present application. Figure 3The battery cell 6 includes a housing 20 and an electrode assembly 10, and the electrode assembly 10 is disposed in the housing 20. The electrode assembly 10 includes a positive electrode and a negative electrode. During the charge and discharge process of the battery cell 6, active ions (such as lithium ions) are embedded and extracted back and forth between the positive electrode and the negative electrode. Optionally, the electrode assembly 10 also includes a separator disposed between the positive electrode and the negative electrode. The separator can reduce the risk of short circuit between the positive and negative electrodes while allowing active ions to pass through.

[0073] The housing 20 is used to encapsulate the electrode assembly 10 and the electrolyte and other components. The housing 20 can be a steel housing, an aluminum housing, a plastic housing (such as polypropylene), a composite metal housing (such as a copper-aluminum composite housing), or an aluminum-plastic film.

[0074] In some embodiments, the housing 20 is a hollow structure, and a space is formed inside the housing to accommodate the electrode assembly 10 and the electrolyte. The shape of the housing 20 can be determined according to the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 is a rectangular parallelepiped structure, a rectangular housing can be used.

[0075] The housing 20 can be made of a variety of materials, for example, metal or plastic. Alternatively, the housing 20 can be made of copper, iron, aluminum, steel, aluminum alloy, etc. For example, the housing 20 can be a steel shell, an aluminum shell, a plastic shell (such as polypropylene), a composite metal shell (such as a copper-aluminum composite shell), or an aluminum-plastic film.

[0076] As an example, the housing 20 includes a shell 21 and an end cover 22 . The shell 21 has an opening, and the end cover 22 is used to cover the opening.

[0077] The housing 21 is a component used to cooperate with the end cover 22 to form an internal cavity of the battery cell 6. The formed internal cavity can be used to accommodate the electrode assembly 10, electrolyte and other components.

[0078] The housing 21 and the end cap 22 may be separate components. For example, an opening may be provided on the housing 21 , and the end cap 22 may be placed over the opening to form an internal cavity of the battery cell 6 .

[0079] The shape of the end cap 22 can be adapted to the shape of the housing 21 to fit the housing 21. The material of the end cap 22 can be the same as or different from that of the housing 21.

[0080] The end cover 22 can be connected to the housing 21 by welding, bonding, clamping or other methods.

[0081] The housing 21 may be open at one end or at both ends. For example, the housing 21 is open at one end, and a single end cap 22 is provided to cover the opening of the housing 21. As another example, the housing 21 may be open at both ends, and two end caps 22 are provided, each of which covers the two openings of the housing 21.

[0082] In some embodiments, the battery cell 6 includes an electrode terminal 30 , which is electrically connected to the electrode assembly 10 for inputting or outputting electrical energy of the battery cell 6 .

[0083] In some embodiments, reference Figure 3 The battery cell 6 includes a housing 20 and an electrode assembly 10 , and the electrode assembly 10 is disposed in the housing 20 .

[0084] Figure 4 is a schematic top view of an electrode assembly of a battery cell provided in some embodiments of the present application, Figure 5 for Figure 4 Schematic diagram of a partial section made along the AA direction. Figure 4 and Figure 5 The electrode assembly 10 includes a first electrode piece 11 and a second electrode piece 12 with opposite polarities.

[0085] Exemplarily, one of the first electrode sheet 11 and the second electrode sheet 12 is a positive electrode sheet, and the other is a negative electrode sheet.

[0086] In some embodiments, the positive electrode sheet may include a positive electrode current collector and a positive electrode film disposed on at least one surface of the positive electrode current collector. For example, the positive electrode current collector may have two opposing surfaces in its thickness direction, and the positive electrode film may be disposed on either or both of the two opposing surfaces of the positive electrode current collector.

[0087] As an example, the positive electrode current collector may be carbon, metal foil or composite current collector. The positive electrode film layer includes a positive electrode active material, which may include at least one of the following materials: lithium-containing phosphate, lithium transition metal oxide and their respective modified compounds.

[0088] In some embodiments, the negative electrode sheet may include a negative electrode current collector and a negative electrode film disposed on at least one surface of the negative electrode current collector. For example, the negative electrode current collector may have two opposing surfaces in its thickness direction, and the negative electrode film may be disposed on either or both of the two opposing surfaces of the negative electrode current collector.

[0089] As an example, the negative electrode current collector may be a metal foil, metal foam, or a composite current collector. The negative electrode film layer includes a negative electrode active material. As an example, the negative electrode active material may 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.

[0090] In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0091] In some embodiments, the electrode assembly 10 further includes a separator 14, which is used to separate the first electrode 11 from the second electrode 12. The separator 14 can reduce the risk of short circuit between the positive and negative electrodes while allowing active ions to pass through.

[0092] In some embodiments, the separator 14 includes an isolation membrane. The isolation membrane of the present application can be any known porous structure isolation membrane with good chemical stability and mechanical stability.

[0093] In some embodiments, the electrode assembly 10 is a wound structure. For example, the first electrode sheet 11 and the second electrode sheet 12 are both strip-shaped structures, and the first electrode sheet 11, the separator 14, and the second electrode sheet 12 are wound into a wound structure.

[0094] In some embodiments, the electrode assembly 10 is a laminated structure. As an example, a plurality of first electrode sheets 11 and a plurality of second electrode sheets 12 may be provided, and the plurality of first electrode sheets 11 and the plurality of second electrode sheets 12 may be alternately stacked.

[0095] Figure 6 is a schematic structural diagram of the second pole piece and liquid retention layer of a battery cell provided in some embodiments of the present application after being flattened. Figure 7 yes Figure 6 Schematic diagram of the cross-sectional structure made along the BB direction, Figure 8 yes Figure 6 Schematic diagram of the cross-sectional structure along the CC direction. Figures 4 to 8 The battery cell 6 provided in the embodiment of the present application includes a shell 20 and an electrode assembly 10 accommodated in the shell 20. The electrode assembly 10 includes a first pole piece 11 and a second pole piece 12 with opposite polarities. The first pole piece 11 and the second pole piece 12 are stacked.

[0096] The first electrode sheet 11 includes a first current collector 111 and a first film layer 112. The first current collector 111 includes a first coating region 113 and a first electrode tab 114 arranged along a first direction X. The first film layer 112 is disposed in the first coating region 113, and the first electrode tab 114 is not provided with the first film layer 112. The first direction X is perpendicular to the thickness direction Y of the first electrode sheet 11. The second electrode sheet 12 includes a second current collector 121 and a second film layer 122. The second current collector 121 includes a second coating region 123 and a blank region 124 arranged along the first direction X. The second film layer 122 is disposed in the second coating region 123, and the blank region 124 is not provided with the second film layer 122. The electrode assembly 10 also includes a liquid retention layer 13 capable of absorbing electrolyte. At least a portion of the liquid retention layer 13 is disposed in the blank region 124 and is located between the first film layer 112 and the blank region 124. Along the direction from the second coating area 123 to the blank area 124 , the liquid retaining layer 13 exceeds the first coating area 113 .

[0097] In some examples, the first electrode sheet 11 is a negative electrode sheet, the first current collector 111 is a negative electrode current collector, the first film layer 112 is a negative electrode film layer and includes a negative electrode active material. The second electrode sheet 12 is a positive electrode sheet, the second current collector 121 is a positive electrode current collector, and the second film layer 122 is a positive electrode film layer and includes a positive electrode active material.

[0098] Alternatively, the first electrode 11 may be a positive electrode, and the second electrode 12 may be a negative electrode.

[0099] The portion of the first current collector 111 where the first film layer 112 is provided forms a first coating region 113 , and the portion of the first current collector 111 where the first film layer 112 is not provided forms a first electrode tab 114 .

[0100] The first coating region 113 has two first surfaces 1131 oppositely arranged along the thickness direction Y of the first pole piece 11 . The first film layer 112 may be formed on one of the first surfaces 1131 or on both first surfaces 1131 .

[0101] The first coating region 113 further has a third end surface 1132, which is connected to the two first surfaces 1131 and faces the first electrode tab 114. The first electrode tab 114 protrudes outward from the third end surface 1132 along the direction from the second coating region 123 to the blank region 124. The third end surface 1132 can be formed by a cutting process.

[0102] In some examples, the first tab 114 and the first coating region 113 are integrally formed, and the first tab 114 can be formed by a die-cutting process. In other examples, the first tab 114 and the first coating region 113 can also be formed independently and connected by welding or other suitable means.

[0103] The first coating area 113 and the first film layer 112 can form a pole piece body of the first pole piece 11 .

[0104] The portion of the second current collector 121 where the second film layer 122 is provided forms a second coating region 123 , and the portion of the second current collector 121 where the second film layer 122 is not provided forms a blank region 124 .

[0105] The second coating region 123 has two third surfaces 1231 oppositely arranged along the thickness direction Y of the first pole piece 11 . The second film layer 122 may be formed on one of the third surfaces 1231 or on both third surfaces 1231 .

[0106] The liquid retaining layer 13 can absorb the electrolyte and has a liquid retaining function. When the liquid retaining layer 13 is subjected to external pressure, it can be compressed and release at least part of the electrolyte it has absorbed.

[0107] Optionally, the liquid retaining layer 13 may have a porous structure to absorb the electrolyte through the pores therein.

[0108] Optionally, the liquid retaining layer 13 may be made of an insulating material with high liquid absorption and liquid retention properties. For example, the material of the liquid retaining layer 13 may include at least one of vinylidene fluoride-hexafluoropropylene copolymer, polymethyl methacrylate, polyethylene oxide, and polyacrylonitrile.

[0109] The liquid retaining layer 13 may be entirely disposed in the blank area 124 , or only a portion of the liquid retaining layer 13 may be disposed in the blank area 124 , and the other portion of the liquid retaining layer 13 may be disposed in the second coating area 123 and / or other locations.

[0110] In some examples, along the thickness direction Y of the first pole piece 11 , the entire liquid retention layer 13 is located between the first film layer 112 and the blank area 124 . Along the thickness direction Y of the first pole piece 11 , the projection of the liquid retention layer 13 is located within the projection of the blank area 124 .

[0111] In other examples, along the thickness direction Y of the first electrode piece 11, a portion of the liquid-retaining layer 13 is located between the first film layer 112 and the blank area 124, and another portion is located outside the space between the first film layer 112 and the blank area 124. Along the thickness direction Y of the first electrode piece 11, the projection of the liquid-retaining layer 13 partially overlaps with the projection of the blank area 124, and the projection of the liquid-retaining layer 13 partially overlaps with the projection of the first film layer 112.

[0112] The liquid retaining layer 13 can be connected to the blank area 124 by bonding, attaching or other appropriate methods.

[0113] The liquid-retaining layer 13 protrudes from the third end surface 1132 along the direction from the second coating area 123 to the blank area 124. Along the thickness direction Y of the first electrode piece 11, the liquid-retaining layer 13 can cover at least a portion of the third end surface 1132, that is, at least a portion of the cut edge of the first electrode piece 11.

[0114] In the embodiment of the present application, a liquid-retaining layer 13 is provided on the second electrode 12. The liquid-retaining layer 13 can absorb a certain amount of electrolyte and thus be in a high-liquid-retaining state. During the charge and discharge process of the battery cell 6, the first film layer 112 expands, compressing the distance between the first electrode 11 and the second electrode 12. The liquid-retaining layer 13 in a high-liquid-retaining state is squeezed, releasing part of the electrolyte, thereby replenishing the electrolyte for the electrochemical reaction of the battery cell 6, which is beneficial to maintaining or improving the cycle performance of the battery cell 6. In addition, the liquid-retaining layer 13 can also cover at least part of the cut edge of the first electrode 11, thereby shielding burrs or metal particles on the edge of the first coating area 113, etc., and playing an insulating and isolating role, which is beneficial to reducing the risk of conduction between the first electrode 11 and the second electrode 12, and improving the reliability of the battery cell 6.

[0115] In some embodiments, the blank area 124 includes a transition area 125 and a second tab 126 arranged along the first direction X. The transition area 125 is connected to the second coating area 123 , and the second tab 126 is arranged on a side of the transition area 125 away from the second coating area 123 . At least a portion of the liquid retention layer 13 is connected to the transition area 125 .

[0116] In the second direction Z, the transition region 125 and the second coating region 123 may have the same size, and the second direction Z, the first direction X, and the thickness direction Y are perpendicular to each other.

[0117] The blank area 124 , the second coating area 123 and the second film layer 122 may form a pole piece body of the second pole piece 12 .

[0118] The blank area 124 and the second coated area 123 are integrally formed. In some examples, the blank area 124 and the second coated area 123 are integrally formed with the second electrode tab 126. In other examples, the blank area 124 and the second coated area 123 are integrally formed with the second electrode tab 126 and can be formed independently and connected by welding or other suitable means.

[0119] The liquid retaining layer 13 may be connected to the transition region 125 by bonding, attaching or other appropriate means.

[0120] Optionally, along the first direction X, the size of the transition zone 125 may be 1 mm to 10 mm.

[0121] Since the transition region 125 is not provided with the second film layer 122, the surface thereof is relatively smooth, the connection strength and stability between the liquid retention layer 13 and the transition region 125 can be improved, and the risk of the liquid retention layer 13 falling off can be reduced. The liquid retention layer 13 at least partially covers the transition region 125, the risk of the blank region 124 being short-circuited with the first tab 11 can be reduced, and a proper amount of electrolyte can be maintained on the surface of the transition region 125, the side reaction between the electrolyte and the transition region 125 can be reduced, and the risk of leakage during high-voltage testing of the battery cell 6 can be reduced.

[0122] In some embodiments, along a direction of the second coating region 123 pointing to the blank region 124, the first film layer 112 protrudes beyond the first end surface 122a of the second film layer 122 facing the blank region 124. Along the thickness direction Y of the first tab 11, the projection of the transition region 125 and the projection of the first film layer 112 at least partially overlap.

[0123] In some examples, along the thickness direction Y of the first tab 11, the projection of the transition region 125 is located within the projection of the first film layer 112. Along the direction of the second coating region 123 pointing to the blank region 124, the transition region 125 does not protrude beyond the first film layer 112.

[0124] In some examples, along the thickness direction Y of the first tab 11, the projection of the transition region 125 is located within the projection of the first film layer 112. Along the direction of the second coating region 123 pointing to the blank region 124, the transition region 125 does not protrude beyond the first film layer 112.

[0125] The first film layer 112 protrudes beyond the first end surface 122a of the second film layer 122, the projection of the transition region 125 and the projection of the first film layer 112 at least partially overlap, which can increase the overlapping area of the liquid retention layer 13 and the second film layer 122 along the thickness direction Y of the first tab 11, thereby increasing the area of the liquid retention layer 13 that can receive the extrusion, which is beneficial to increase the compression deformation amount of the liquid retention layer 13 and increase the amount of electrolyte released by the liquid retention layer 13.

[0126] In some embodiments, along the thickness direction Y of the first tab 11, the liquid retention layer 13 completely covers the transition region 125. In other words, the transition region 125 will not be directly exposed to the outside of the first tab 11, which further reduces the risk of the blank region 124 being short-circuited with the first tab 11, and a balanced amount of electrolyte can be maintained on the surface of the transition region 125, which further reduces the side reaction between the electrolyte and the transition region 125 and the risk of leakage during high-voltage testing of the battery cell 6.

[0127] In some embodiments, at least part of the liquid retention layer 13 is bonded to the transition region 125.

[0128] The liquid retaining layer 13 can include a liquid absorbing layer 13a and a glue layer 13b, the glue layer 13b being arranged on a side of the liquid absorbing layer 13a facing the blank area 124 and at least partially adhering to the transition area 125.

[0129] The liquid absorbing layer 13a can be of a porous structure to facilitate absorption of the electrolyte and release of part of the electrolyte after being pressed.

[0130] The thickness of the glue layer 13b is less than that of the liquid absorbing layer 13a, so as to increase the thickness of the liquid absorbing layer 13a as much as possible in a limited space and improve the liquid retaining capacity of the liquid retaining layer 13.

[0131] The embodiment of the present application adheres at least part of the liquid retaining layer 13 to the transition area 125, which can improve the connection strength of the liquid retaining layer 13 and the blank area 124 and reduce the risk of falling off of the liquid retaining layer 13. Moreover, the structure of the liquid retaining layer 13 is relatively stable, which is conducive to reducing the possibility of adversely affecting the second tab 12, facilitating control of the position of the liquid retaining layer 13 relative to the second tab 12 during assembly, and enabling the liquid retaining layer 13 to be adhered to the second tab 12 during cutting of the second tab 12, thus improving the assembly efficiency.

[0132] In some embodiments, along a direction of the blank area 124 pointing to the second coating area 123, the liquid retaining layer 13 exceeds the first end surface 122a of the second film layer 122 facing the blank area 124.

[0133] Along the thickness direction Y of the first tab 11, part of the liquid retaining layer 13 is located on a side of the second film layer 122 away from the second current collector 121 and covers part of the second film layer 122. The projection of the liquid retaining layer 13 and the projection of the second film layer 122 partially overlap.

[0134] Along a direction of the blank area 124 pointing to the second coating area 123, the liquid retaining layer 13 exceeds the first end surface 122a, and the liquid retaining layer 13 can completely cover the junction between the second coating area 123 and the transition area 125, reducing the possibility of exposure of the side of the transition area 125 close to the second coating area 123, so as to reduce the risk of short circuiting of the transition area 125 and the first tab 11.

[0135] In some embodiments, along a direction of the blank area 124 pointing to the second coating area 123, the size d1 of the liquid retaining layer 13 exceeding the first end surface 122a is 0.5 mm to 3 mm.

[0136] Optionally, d1 can be 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm, 3.5 mm or 3 mm, etc.

[0137] If the dimension d1 by which the liquid-retaining layer 13 extends beyond the first end surface 122a is too small, the liquid-retaining layer 13 may easily warp relative to the second film layer 122, creating a gap therebetween and affecting the connection between the liquid-retaining layer 13 and the transition region 125. If the dimension d1 by which the liquid-retaining layer 13 extends beyond the first end surface 122a is too large, the liquid-retaining layer 13 covers a larger area of ​​the second film layer 122, potentially affecting the capacity of the second film layer 122 and thereby reducing the capacity of the battery cell 6.

[0138] In the embodiment of the present application, the dimension d1 of the liquid retaining layer 13 extending beyond the first end surface 122a is set to 0.5 mm to 3 mm, which is beneficial for improving the effect of the liquid retaining layer 13 covering the transition area 125 and the connection stability between the liquid retaining layer 13 and the transition area 125, and is beneficial for reducing the adverse effects on the capacity of the battery cell 6.

[0139] In some embodiments, the second film layer 122 includes a main region 1221 and a thinned region 1222 arranged along the first direction X. The thinned region 1222 is connected to the main region 1221 and is located on the side of the main region 1221 facing the blank region 124. The thickness of the main region 1221 is greater than that of the thinned region 1222. Along the thickness direction Y of the first electrode 11, the liquid-retaining layer 13 covers at least a portion of the thinned region 1222, and the projection of the liquid-retaining layer 13 is separated from the projection of the main region 1221.

[0140] The main region 1221 may be a substantially uniform thickness structure, and the thinned region 1222 may be a substantially uniform thickness structure or a unequal thickness structure.

[0141] In some examples, along the direction from the second coating area 123 to the blank area 124 , the thickness of the thinned area 1122 may decrease gradually or in sections.

[0142] In the embodiment of the present application, the thickness of the main region 1221 is greater than the thickness of the thinned region 1222 , which means that the average thickness of the main region 1221 is greater than the average thickness of the thinned region 1222 .

[0143] Along the thickness direction Y of the first pole piece 11 , the liquid retention layer 13 may cover the entire thinned area 1222 , or may only cover a portion of the thinned area 1222 .

[0144] Along the thickness direction Y of the first electrode 11, the projection of the liquid-retaining layer 13 and the projection of the main body region 1221 do not overlap, and there is no thickness overlap between the liquid-retaining layer 13 and the main body region 1221. However, the liquid-retaining layer 13 and the thinned region 1222 do overlap in thickness. The thinned region 1222 is relatively thin, allowing the reduced space within the thinned region 1222 to accommodate a portion of the liquid-retaining layer 13. This improves space utilization, reduces the combined thickness of the liquid-retaining layer 13 and the thinned region 1222, saves space, and reduces the possibility of bulging at the edge of the electrode assembly 10.

[0145] In some embodiments, along the direction from the second coating area 123 to the blank area 124 , the liquid retention layer 13 extends beyond the transition area 125 and faces the second end surface 1251 of the second electrode tab 126 .

[0146] Along the direction from the second coating area 123 to the blank area 124 , the portion of the liquid retaining layer 13 extending beyond the second end surface 1251 may cover a portion of the second electrode tab 126 , or may not cover the second electrode tab 126 .

[0147] The second end surface 1251 of the transition region 125 can be formed by a cutting process. During the cutting process, burrs or metal particles may exist on the second end surface 1251.

[0148] Along the direction from the second coating region 123 to the blank region 124, the liquid-retaining layer 13 extends beyond the first end surface 122a. The liquid-retaining layer 13 can completely cover the second end surface 1251, reducing the possibility of the side of the transition region 125 near the second electrode tab 126 being exposed, thereby reducing the risk of short circuit between the transition region 125 and the first electrode sheet 11. More importantly, the liquid-retaining layer 13 can also cover at least a portion of the cut edge of the second electrode sheet 12, thereby shielding burrs or metal particles on the second end surface 1251, providing insulation and isolation, further reducing the risk of electrical conduction between the first electrode sheet 11 and the second electrode sheet 12, and improving the reliability of the battery cell 6.

[0149] In some embodiments, along the direction from the second coating area 123 to the blank area 124 , the dimension d2 of the liquid retaining layer 13 extending beyond the second end surface 1251 is 1 mm to 5 mm.

[0150] Optionally, d2 can be 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm or 5mm, etc.

[0151] If the dimension d2 by which the liquid-retaining layer 13 extends beyond the second end surface 1251 is too small, and the burr formed on the second end surface 1251 is too long, the burr may still overlap the first electrode piece 11. If the dimension d2 by which the liquid-retaining layer 13 extends beyond the second end surface 1251 is too large, the liquid-retaining layer 13 may easily interfere with the first electrode tab 114 and / or the second electrode tab 126, affecting the connection between the first electrode tab 114 and / or the second electrode tab 126 and other structures.

[0152] In the embodiment of the present application, the dimension d2 of the liquid retaining layer 13 extending beyond the second end surface 1251 is set to 1 mm to 5 mm, which can not only improve the effect of the liquid retaining layer 13 in shielding burrs, but also help reduce the possibility of interference with the first electrode tab 114 and / or the second electrode tab 126.

[0153] In some embodiments, the second end surface 1251 includes a tab lead-out area 1251 a and a non-tab lead-out area 1251 b , and the second tab 126 extends only from the tab lead-out area 1251 a and protrudes from the liquid retention layer 13 in a direction away from the transition area 125 .

[0154] There may be one or more tab lead-out regions 1251a. For example, the number of tab lead-out regions 1251a corresponds to the number of second tabs 126. After the second tab 126 is cut off along the second end surface 1251, the tab lead-out regions 1251a are exposed.

[0155] There can be one or more non-tab lead-out regions 1251b.

[0156] Illustratively, there are multiple tab lead-out regions 1251a and multiple non-tab lead-out regions 1251b, and the tab lead-out regions 1251a and the non-tab lead-out regions 1251b are alternately arranged.

[0157] The second electrode tab 126 protrudes from the liquid retaining layer 13 to facilitate connection with other conductive structures, thereby reducing the risk of interference between the liquid retaining layer 13 and the conductive structures.

[0158] Along the direction from the second coating area 123 to the blank area 124, the portion of the liquid retaining layer 13 that exceeds the second end surface 1251 can be only arranged on the outside of the non-pole tab lead-out area 1251b along the first direction X. Along the thickness direction Y of the first electrode piece 11, the liquid retaining layer 13 does not cover the second pole tab 126, which can increase the length of the second pole tab 126 that can be connected to the conductive structure, further reducing the risk of interference between the liquid retaining layer 13 and the conductive structure.

[0159] In other embodiments, the liquid retaining layer 13 includes a first liquid retaining portion 131 and a second liquid retaining portion 132, at least a portion of the first liquid retaining portion 131 is located in the transition zone 125, and the second liquid retaining portion 132 includes a first extension portion 1321 and a second extension portion 1322, the first extension portion 1321 is located on the outside of the non-pole tab lead-out area 1251b along the first direction X, and the second extension portion 1322 is located on the outside of the pole tab lead-out area 1251a along the first direction X, and covers a portion of the second pole tab 126 along the thickness direction Y of the first pole piece 11.

[0160] For example, a plane parallel to the first direction X and passing through the junction of the tab lead-out region 1251 a and the non-tab lead-out region 1251 b may be the interface between the first extension portion 1321 and the second extension portion 1322 .

[0161] In the first direction X, the size of the first extending portion 1321 and the size of the second extending portion 1322 may be equal or unequal.

[0162] In some examples, the dimension of the first extension portion 1321 along the first direction X is equal to the dimension of the second extension portion 1322 along the first direction X, and the liquid retaining layer 13 is arranged with equal width, which is easy to shape.

[0163] The first liquid holding portion 131 may include a liquid absorbing layer 13a and an adhesive layer 13b, and is bonded to the transition region 125 via the adhesive layer 13b.

[0164] The second liquid-retaining portion 132 may include only the liquid-absorbing layer 13a, or may include both the liquid-absorbing layer 13a and the adhesive layer 13b. For example, the second extension 1322 includes both the liquid-absorbing layer 13a and the adhesive layer 13b, and is bonded to the second electrode tab 126 via the adhesive layer 13b, thereby increasing the structural strength of the second electrode tab 126 and reducing the risk of cracking during bending.

[0165] Along the thickness direction Y, the first extension portion 1321 may cover the non-tab lead-out region 1251 b to shield burrs or metal particles on the non-tab lead-out region 1251 b .

[0166] Along the thickness direction Y, the second extension portion 1322 can cover the root of the second electrode tab 126 near the transition region 125, thereby shielding burrs at the root of the second electrode tab 126 and reducing the risk of cracking at the root of the second electrode tab 126. Furthermore, the risk of the second electrode tab 126 being inserted upside down between the first electrode sheet 11 and the second electrode sheet 12 when bent can be reduced.

[0167] In some embodiments, the first coating region 113 has two first surfaces 1131 disposed opposite each other along the thickness direction Y of the first electrode piece 11. The first electrode piece 11 includes two first film layers 112, which are disposed on the two first surfaces 1131, respectively. At least one liquid retention layer 13 is disposed on each side of the second electrode piece 12 along the thickness direction Y of the first electrode piece 11.

[0168] It can be understood that the second coating area 123 has two third surfaces 1231 arranged opposite to each other along the thickness direction Y of the first pole piece 11. One of the third surfaces 1231 can be provided with the second film layer 122, or both third surfaces 1231 can be provided with the second film layer 122.

[0169] Each side of the second electrode 12 along the thickness direction Y may be provided with only one liquid retaining layer 13 or multiple liquid retaining layers 13 . The multiple liquid retaining layers 13 may be stacked along the first direction X or laminated along the thickness direction Y.

[0170] Optionally, the liquid retaining layers 13 on both sides of the second pole piece 12 may be symmetrically arranged or asymmetrically arranged.

[0171] Along the thickness direction Y of the first electrode piece 11, the first film layers 112 of the two first electrode pieces 11 located on both sides of the second electrode piece 12 can respectively squeeze the two liquid retention layers 13 of the second electrode piece 12 when they expand. Both liquid retention layers 13 can release electrolyte, which is beneficial to improve the liquid replenishment capacity and further improve the cycle performance of the battery cell 6.

[0172] In some embodiments, along the direction from the second coating area 123 to the blank area 124 , at least a portion of the liquid retaining layer 13 on both sides of the second electrode 12 that extends beyond the second end surface 1251 is bonded to each other.

[0173] Optionally, the liquid retaining layer 13 may include a first liquid retaining portion 131 and a second liquid retaining portion 132 , wherein at least a portion of the first liquid retaining portion 131 is disposed in the transition area 125 , and the second liquid retaining portion 132 extends beyond the second end surface 1251 along the direction from the second coating area 123 to the blank area 124 .

[0174] In some examples, the second liquid retaining portions 132 may be entirely disposed outside the non-tab lead-out region 1251 b along the first direction X, and the second liquid retaining portions 132 of the liquid retaining layer 13 on both sides of the second electrode 12 may be bonded to each other.

[0175] In other examples, the second liquid retaining portion 132 may include a first extension portion 1321 and a second extension portion 1322, wherein the first extension portion 1321 is disposed outside the non-tab lead-out region 1251b along the first direction X, and the second extension portion 1322 is disposed outside the tab lead-out region 1251a along the first direction X. The first extension portions 1321 of the liquid retaining layer 13 located on both sides of the second electrode piece 12 are bonded to each other.

[0176] Optionally, the liquid retaining layer 13 may include a liquid absorbing layer 13a and a glue layer 13b, wherein the glue layer 13b is disposed on a side of the liquid absorbing layer facing the second current collector 121. The glue layer 13b is at least located on a portion of the liquid absorbing layer 13a that extends beyond the second end surface 1251.

[0177] The liquid-retaining layers 13 on both sides of the second electrode piece 12 are bonded together, which can improve the connection strength between the liquid-retaining layers 13 and the second electrode piece 12 and reduce the risk of the liquid-retaining layers 13 falling off. The liquid-retaining layers 13 can cover the second end surface 1251, and the bonded portion has relatively high structural strength and is not easily punctured by burrs, which helps to improve the burr shielding effect.

[0178] In some embodiments, along the direction from the second coating region 123 to the second film layer 122 , the liquid-retaining layer 13 does not extend beyond the second surface 1223 of the second film layer 122 facing away from the second coating region 123 .

[0179] The surface of the liquid-retaining layer 13 facing away from the second coating area 123 may be flush with the second surface 1223 , or may be recessed into the second surface 1223 toward the second coating area 123 .

[0180] The provision of the liquid retaining layer 13 does not increase the thickness of the edge of the second electrode sheet 12 , thereby reducing the possibility of bulging of the edge of the electrode assembly 10 .

[0181] In some embodiments, the maximum thickness of the liquid retaining layer 13 is less than the maximum thickness of the second film layer 122 .

[0182] For example, the second film layer 122 may have a substantially uniform thickness, and the maximum thickness of the second film layer 122 is its average thickness.

[0183] As another example, the second film layer 122 may also have a non-uniform thickness. For example, the second film layer 122 includes a main region 1221 and a thinned region 1222. The main region 1221 has a substantially uniform thickness that is greater than the average thickness of the thinned region 1222. The maximum thickness of the second film layer 122 is the uniform thickness of the main region 1221.

[0184] The liquid retaining layer 13 may have a substantially uniform thickness or a non-uniform thickness. For example, the portion of the liquid retaining layer 13 covering the blank area 124 has the largest thickness.

[0185] In the embodiment of the present application, the maximum thickness of the liquid retaining layer 13 is set to be smaller than the maximum thickness of the second film layer 122. Along the direction of the second coating area 123 pointing to the second film layer 122, the second film layer 122 can extend beyond the surface of the liquid retaining layer 13 away from the second coating area 123, which is beneficial to reducing the overall thickness of the edge of the second electrode plate 12 and reducing the possibility of bulging of the edge of the electrode assembly 10.

[0186] In some embodiments, the electrode assembly 10 further includes a separator 14 disposed between the first electrode piece 11 and the second electrode piece 12. The expansion coefficient of the first film layer 112 is K, the maximum thickness of the overlapping portion of the first film layer 112 and the liquid retaining layer 13 along the thickness direction Y is D1, the minimum separation distance between the first film layer 112 and the liquid retaining layer 13 along the thickness direction Y is L, and the thickness of the separator 14 is D2. K, D1, L, and D2 satisfy the following: K×D1>L-D2.

[0187] The thickness of the overlapping portion of the first film layer 112 and the liquid retaining layer 13 along the thickness direction Y may be uniform or non-uniform.

[0188] The first film layer 112 overlaps with the liquid retaining layer 13 along the thickness direction Y, and a portion with the largest thickness is closest to the liquid retaining layer 13 and has a minimum spacing distance from the liquid retaining layer 13 .

[0189] In the embodiment of the present application, K, D1, L and D2 are set to: K×D1>L-D2. After the first film layer 112 expands, the first film layer 112 overlaps with the liquid retaining layer 13 along the thickness direction Y and the part with the largest thickness can contact and squeeze the liquid retaining layer 13, so that the liquid retaining layer 13 can release the electrolyte more effectively.

[0190] In some embodiments, the first electrode 11 is a negative electrode, the second electrode 12 is a positive electrode, and the first film layer 112 includes a silicon-based material.

[0191] During the charge and discharge process of the battery cell 6 , the volume expansion of the silicon-based material is relatively obvious. The first film layer 112 having the silicon-based material can more effectively squeeze the liquid retaining layer 13 on the second electrode 12 by expansion, thereby more effectively replenishing the electrolyte.

[0192] According to the second aspect of the present application, an embodiment of the present application further provides a battery device 2, which includes a plurality of battery cells 6 provided according to any embodiment of the present application.

[0193] According to a third aspect of the present application, an embodiment of the present application further provides an electrical device, which includes a battery device 2 provided according to any embodiment of the present application, and the battery device 2 is used to provide electrical energy.

[0194] An embodiment of the present application provides a battery cell 6, which includes a shell 20 and an electrode assembly 10 accommodated in the shell 20. The electrode assembly 10 includes a first electrode sheet 11 and a second electrode sheet 12 stacked together. The first electrode sheet 11 is a negative electrode sheet, and the second electrode sheet 12 is a positive electrode sheet.

[0195] The first pole piece 11 includes a first current collector 111 and a first film layer 112. The first current collector 111 includes a first coating area 113 and a first electrode tab 114 arranged along a first direction X. The first film layer 112 is arranged in the first coating area 113, and the first electrode tab 114 is not provided with the first film layer 112. The first direction X is perpendicular to the thickness direction Y of the first pole piece 11. The second pole piece 12 includes a second current collector 121 and a second film layer 122. The second current collector 121 includes a second coating area 123 and a blank area 124 arranged along the first direction X. The second film layer 122 is arranged in the second coating area 123, and the blank area 124 is not provided with the second film layer 122.

[0196] The electrode assembly 10 also includes a liquid-retention layer 13 located on both sides of the second electrode sheet 12 along the thickness direction Y. The liquid-retention layer 13 is capable of absorbing electrolyte. At least a portion of the liquid-retention layer 13 is located within the blank area 124 and between the first film layer 112 and the blank area 124. The material of the liquid-retention layer 13 may include at least one of vinylidene fluoride-hexafluoropropylene copolymer, polymethyl methacrylate, polyethylene oxide, and polyacrylonitrile. The liquid-retention layer 13 extends beyond the first coating area 113 in the direction from the second coating area 123 toward the blank area 124. Along the direction from the blank area 124 toward the second coating area 123, the liquid-retention layer 13 extends beyond the first end surface 122a of the second film layer 122 facing the blank area 124 by a dimension d1 of 0.5 mm to 3 mm. Along the direction from the second coating area 123 toward the blank area 124, the liquid-retention layer 13 extends beyond the second end surface 1251 of the transition area 125 facing the second electrode tab 126 by a dimension d2 of 1 mm to 5 mm. The blank area 124 includes a transition area 125 and a second tab 126 arranged along the first direction X. The transition area 125 is connected to the second coating area 123. The second tab 126 is arranged on a side of the transition area 125 away from the second coating area 123. Along the first direction X, the size of the transition area 125 is 1 mm to 10 mm.

[0197] The electrode assembly 10 also includes a separator 14, which is disposed between the first electrode piece 11 and the second electrode piece 12. The expansion coefficient of the first film layer 112 is K. The maximum thickness of the overlapping portion of the first film layer 112 and the liquid-retaining layer 13 along the thickness direction Y is D1. The minimum separation distance between the first film layer 112 and the liquid-retaining layer 13 along the thickness direction Y is L. The thickness of the separator 14 is D2. K, D1, L, and D2 satisfy the following relationship: K×D1>L-D2.

[0198] 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 or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell, characterized in that: The device comprises a housing and an electrode assembly contained in the housing, wherein the electrode assembly comprises a first electrode piece and a second electrode piece with opposite polarities, wherein the first electrode piece and the second electrode piece are stacked; The first pole piece includes a first current collector and a first film layer, the first current collector includes a first coating area and a first electrode tab arranged along a first direction, the first film layer is arranged in the first coating area, and the first electrode tab is not provided with the first film layer, and the first direction is perpendicular to the thickness direction of the first pole piece; The second pole piece includes a second current collector and a second film layer, the second current collector includes a second coating area and a blank area arranged along the first direction, the second film layer is arranged in the second coating area, and the second film layer is not arranged in the blank area; The electrode assembly further includes a liquid retaining layer capable of absorbing electrolyte, wherein at least a portion of the liquid retaining layer is disposed in the blank area and between the first film layer and the blank area; Along the direction from the second coating area to the blank area, the liquid-retaining layer exceeds the first coating area.

2. The battery cell according to claim 1, wherein: The blank area includes a transition area and a second tab arranged along the first direction, the transition area is connected to the second coating area, and the second tab is arranged on a side of the transition area away from the second coating area; At least a portion of the liquid-retaining layer is connected to the transition zone.

3. The battery cell according to claim 2, characterized in that: Along the direction from the second coating area to the blank area, the first film layer extends beyond the second film layer and faces the first end surface of the blank area; Along the thickness direction, a projection of the transition region and a projection of the first film layer at least partially overlap.

4. The battery cell according to claim 2, characterized in that: Along the thickness direction, the liquid-retaining layer completely covers the transition zone.

5. The battery cell according to claim 2, characterized in that: At least a portion of the liquid-retaining layer is bonded to the transition zone.

6. The battery cell according to claim 2, characterized in that Along the direction from the blank area to the second coating area, the liquid-retaining layer extends beyond the second film layer to a first end surface facing the blank area.

7. The battery cell according to claim 6, characterized in that The second film layer includes a main region and a thinning region arranged along the first direction, the thinning region is connected to the main region and is located on a side of the main region facing the blank region, and the thickness of the main region is greater than the thickness of the thinning region; Along the thickness direction, the liquid-retaining layer covers at least a portion of the thinned area, and a projection of the liquid-retaining layer is separated from a projection of the main area.

8. The battery cell according to claim 6, characterized in that Along the direction from the blank area to the second coating area, the dimension of the liquid retaining layer extending beyond the first end surface is 0.5 mm to 3 mm.

9. The battery cell according to claim 2, characterized in that: Along the direction from the second coating area to the blank area, the liquid retention layer extends beyond the transition area and faces the second end surface of the second electrode tab.

10. The battery cell according to claim 9, characterized in that Along the direction from the second coating area to the blank area, the liquid retaining layer extends beyond the second end surface by 1 mm to 5 mm.

11. The battery cell according to claim 9, characterized in that The second end surface includes a tab lead-out area and a non-tab lead-out area, and the second tab extends only from the tab lead-out area and protrudes from the liquid retaining layer in a direction away from the transition area; The liquid retaining layer includes a first liquid retaining portion and a second liquid retaining portion, at least a portion of the first liquid retaining portion is arranged in the transition zone, and the second liquid retaining portion includes a first extension portion and a second extension portion, the first extension portion is arranged on the outside of the non-tab lead-out area along the first direction, and the second extension portion is arranged on the outside of the tab lead-out area along the first direction, and covers a portion of the second tab along the thickness direction.

12. The battery cell according to claim 9, characterized in that The first coating area has two first surfaces arranged opposite to each other along the thickness direction, and the first pole piece includes two first film layers, which are respectively arranged on the two first surfaces; At least one liquid retaining layer is provided on both sides of the second pole piece along the thickness direction.

13. The battery cell according to claim 12, characterized in that: Along the direction from the second coating area to the blank area, at least parts of the liquid retaining layer on both sides of the second pole piece that extend beyond the second end surface are bonded to each other.

14. The battery cell according to claim 1, characterized in that Along the direction from the second coating area to the second film layer, the liquid-retaining layer does not extend beyond the second surface of the second film layer away from the second coating area.

15. The battery cell according to claim 1, characterized in that The maximum thickness of the liquid retaining layer is smaller than the maximum thickness of the second film layer.

16. The battery cell according to claim 1, characterized in that The electrode assembly further includes a separator, which is disposed between the first electrode piece and the second electrode piece; The expansion coefficient of the first film layer is K, the maximum thickness of the overlapping part of the first film layer and the liquid-retaining layer along the thickness direction is D1, the minimum spacing distance between the first film layer and the liquid-retaining layer along the thickness direction is L, the thickness of the isolation member is D2, and K, D1, L and D2 satisfy: K×D1>L-D2.

17. The battery cell according to claim 1, characterized in that The first electrode is a negative electrode, the second electrode is a positive electrode, and the first film layer includes a silicon-based material.

18. A battery device, characterized in that: The invention comprises a plurality of battery cells according to any one of claims 1 to 17.

19. An electrical device, characterized in that: The battery device according to claim 18 is included, and is used to provide electrical energy.

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