Battery cells, battery packs and electrical devices

Abstract

A battery cell (20), a battery device (100), and an electrical device (1000) are provided. The battery cell includes: a housing assembly (21); an electrode assembly (22) disposed within the housing assembly and including a first electrode (221), a second electrode (222), and a separator (223), wherein the separator is disposed between the first electrode and the second electrode, the electrode assembly includes a winding axis, the electrode assembly is a core-shaped structure wound around the winding axis, and includes multiple winding layers perpendicular to the winding axis, wherein the winding layers include the first electrode, the separator, and the second electrode stacked together; and a buffer (23) disposed within at least one winding layer and located between the separator and the first electrode, or between the separator and the second electrode.

Description

Battery cell, battery device and electric device TECHNICAL FIELD

[0001] The present application relates to the field of battery, in particular to a battery cell, a battery device and an electric device. BACKGROUND

[0002] In recent years, new energy vehicles have made a great leap in development. In the field of electric vehicles, power batteries, as the power source of electric vehicles, play an irreplaceable important role. The battery is composed of a box body and a plurality of battery cells contained in the box body. Among them, the battery as a core component of new energy vehicles has high requirements in terms of safety and service life. However, during the cyclic charging and discharging process of the battery cells in the battery, as the cycle number increases, the pole pieces inside the battery cells are prone to swelling, affecting the reliability of the battery cells.

[0003] SUMMARY

[0004] The embodiments of the present application provide a battery cell, a battery device and an electric device, which can effectively alleviate the swelling problem of the pole pieces inside the battery cell, and can improve the reliability of the battery cell and the electric device.

[0005] In a first aspect, the embodiments of the present application provide a battery cell, comprising: a shell assembly; an electrode assembly arranged in the shell assembly and comprising a first pole piece, a second pole piece and a separator film, the separator film being arranged between the first pole piece and the second pole piece, the electrode assembly comprising a winding axial direction, the electrode assembly being a winding core structure wound around the winding axial direction and comprising a plurality of winding layers perpendicular to the winding axial direction, the winding layer comprising the first pole piece, the separator film and the second pole piece arranged in layers; and a buffer member arranged in at least one winding layer and located between the separator film and the first pole piece or between the separator film and the second pole piece.

[0006] In the above technical solution, since the buffer member is arranged in at least one winding layer and located between the separator film and the first pole piece or between the separator film and the second pole piece, the buffer member can play a buffering role between the outer pole piece and the inner pole piece of the electrode assembly, can provide the space required for the expansion of the inner pole piece and the outer pole piece at the same time, effectively alleviate the situation that the expansion force of the inner pole piece is accumulated on the outer pole piece, and is beneficial to reducing the tensile force received by the outer pole piece, thereby reducing the probability of fracture of the outer pole piece and improving the reliability of the battery cell. Moreover, since the buffer member is arranged in the winding layer, the buffer member can be assembled into the shell together with the electrode assembly when the electrode assembly enters the shell, which can make the assembly of the buffer member in the battery cell simpler and is beneficial to reducing the overall assembly difficulty of the battery cell.

[0007] In some embodiments of the present application, the electrode assembly comprises a connected main body and a tab, the main body comprises a connected flat portion and an arc-shaped portion, and the buffer is arranged on the arc-shaped portion.

[0008] In the above technical solution, the arc-shaped portion of the main body is in an arc-shaped structure and has a change in curvature, so that stress concentration is more likely to occur during the cyclic expansion of the electrode assembly, and the arc-shaped portion bears greater expansion tensile force than other positions of the main body. By arranging the buffer on the arc-shaped portion, when the first and / or second electrode tab at the position corresponding to the arc-shaped portion expands, the buffer can be compressed to absorb energy, reduce the expansion tensile force, and provide the space required for the expansion of the first and / or second electrode tab, thereby reducing the risk of electrode tab fracture at the position of the arc-shaped portion, and reducing the probability of overall expansion fracture of the electrode assembly, thereby improving the reliability of the battery cell. Since the buffer is arranged on the arc-shaped portion, the area of the buffer on the main body can be reduced, which can save materials and reduce costs, and also reduce the volume of the buffer, save internal space of the shell assembly, and reduce the weight of the buffer, thereby reducing the overall weight of the battery cell, thereby improving the volumetric energy density of the battery cell.

[0009] In some embodiments of the present application, the buffer is bonded to the first or second electrode tab.

[0010] In the above technical solution, by bonding the buffer to the first or second electrode tab, the buffer can be fixed on the first or second electrode tab, which is conducive to reducing the risk of displacement of the buffer during the winding process of the electrode assembly, and reducing the probability of the buffer separating from the position of the arc-shaped portion, thereby improving the stability of the buffer in the electrode assembly, improving the buffering and expansion fracture inhibition effect of the buffer on the outermost electrode tab of the electrode assembly, and further improving the reliability of the battery cell.

[0011] In some embodiments of the present application, an adhesive piece is arranged on the end surface of the buffer facing the separator, and in the winding direction of the arc-shaped portion, the two ends of the adhesive piece protrude beyond the buffer and are bonded to the first or second electrode tab.

[0012] In the above technical solution, the adhesive piece is a separate component and can be mass-produced, which is conducive to ensuring controllable adhesion, thereby making the adhesion force more uniform when the adhesive piece is bonded to the first or second electrode tab, improving the reliability of the buffer fixed on the first or second electrode tab, and the fixing method is relatively simple and easy to operate, which is conducive to improving the assembly efficiency. Secondly, the buffer can be fixed on the first or second electrode tab through the adhesive piece on the basis of being bonded to the first or second electrode tab, which can further improve the installation reliability of the buffer, reduce the risk of the buffer separating from the first or second electrode tab, improve the buffering effect of the buffer on the electrode tab at the position of the arc-shaped portion, and further reduce the probability of expansion fracture of the outermost electrode tab.

[0013] In some embodiments of the present application, the buffer is centrally arranged on the arc portion in the winding direction of the arc portion.

[0014] In the above technical solution, since the arc portion of the electrode assembly itself has the problem of stress concentration, and the middle position of the arc portion is a relatively large stress point, the buffer is centrally arranged on the arc portion, thereby specifically relieving the stress concentration phenomenon of the arc portion, which is conducive to the buffer to better absorb and disperse stress, and to reduce the stress size borne by the middle position of the arc portion. Secondly, the central arrangement of the buffer on the arc portion is also conducive to balancing the stress distribution inside the entire electrode assembly, which can diffuse the stress originally concentrated in the middle position of the arc portion to the periphery, so that the stress of each part of the electrode assembly is more uniform, thereby reducing the risk of swelling and fracture of the outer electrode sheet caused by local large stress, and improving the reliability of the electrode assembly, and further improving the overall reliability of the battery cell.

[0015] In some embodiments of the present application, in the winding direction of the arc portion, the size of the winding layer in which the buffer is arranged in the arc portion is L1, and the size of the buffer is L2, wherein 0

[0016] In the above technical solution, by setting the ratio of the size L2 of the buffer to the size L1 of the winding layer in which the buffer is arranged in the arc portion within the above range, the size of the buffer does not exceed the size of the winding layer in which the buffer is arranged in the arc portion, so that the buffer does not extend to the flat portion, reducing the risk that the buffer will appear a bending position between the first electrode sheet or the second electrode sheet when it is in the flat portion, and causing the first electrode sheet or the second electrode sheet to concentrate stress and break, which can improve the reliability of the electrode assembly when the buffer is arranged in the winding layer. Since the buffer does not extend to the flat portion, it is also conducive to reducing the volume of the buffer, saving space, and reducing the weight of the buffer, and further reducing the overall weight of the battery cell, thereby improving the volumetric energy density of the battery cell.

[0017] In some embodiments of the present application, a plurality of buffers are arranged on the arc portion, the plurality of buffers are arranged at intervals in the winding direction of the arc portion, and are symmetrically arranged. In this technical solution, the above scheme can further reduce the volume of the buffer, thereby further saving space, which is conducive to improving the volume ratio of the electrode assembly in the shell assembly, and further reducing the weight of the buffer, and further reducing the overall weight of the battery cell, thereby further improving the volumetric energy density of the battery cell.

[0018] In some embodiments of the present application, in the winding direction of the arc portion, the buffer has a center surface, and two buffers are arranged on the arc portion, and the center surface of the buffer and the quarter division line of the arc length of the arc portion are close to or coincide.

[0019] In the technical solution, the position of the quarter division line of the arc length of the arc-shaped portion is close to the position of the two end edges of the arc-shaped portion, and the position of the two end edges of the arc-shaped portion is a key point of stress dispersion. By making the center surface of the buffer member close to or coincide with the quarter division line, the buffer member can better adapt to the direction of stress transmission, disperse the stress to a wider area, and reduce the degree of local stress concentration. When the electrode assembly is bent and deformed, the two end positions of the arc-shaped portion first bear the bending stress. The above-mentioned solution can effectively absorb and buffer the bending stress, reduce the risk of damage to the internal structure of the electrode assembly due to excessive bending, improve the reliability of the electrode assembly, and further improve the overall reliability of the battery cell. Moreover, the above-mentioned solution can also make the first electrode sheet or the second electrode sheet form a certain gap at the middle position of the arc-shaped portion in the winding layer where the buffer member is located, which can provide the space required for the expansion of the middle position of the arc-shaped portion, is also conducive to reducing the probability of stress concentration at the middle position of the arc-shaped portion, and can improve the reliability of the battery cell.

[0020] On the other hand, since the arc-shaped portion has an arc-shaped structure and the shell assembly generally has a square shape, a certain gap will be formed between the arc-shaped portion at the two ends of the winding direction and the shell assembly. By making the center surface of the two buffer members close to or coincide with the quarter division line of the arc length of the arc-shaped portion, the gap formed between the arc-shaped portion and the shell assembly can be fully utilized to arrange the buffer members, reducing the risk of increasing the size of the electrode assembly due to the arrangement of the buffer members in the winding layer, improving the space ratio of the electrode assembly in the shell assembly, and helping to make the battery cell have a high volumetric energy density.

[0021] In some embodiments of the present application, the opposite ends of the flat portion are provided with arc-shaped portions, and the two arc-shaped portions are each provided with a buffer member. In this technical solution, the buffer member can provide space required for expansion for each arc-shaped portion, and can provide a buffer effect and space required for expansion in time when each arc-shaped portion expands, thereby reducing the risk of expansion and fracture of the outer electrode sheet at the position of the arc-shaped portion, further improving the reliability of the electrode assembly, and further improving the reliability of the battery cell.

[0022] In some embodiments of the present application, the buffer members of the two arc-shaped portions are arranged in the same winding layer or in different winding layers.

[0023] In the technical solution, the two arc-shaped buffer members are arranged in the same winding layer, so that the buffer members can buffer the stress generated in the layer, can timely absorb and disperse the stress, effectively reduce the risk of stress concentration in a local area, better protect the first or second pole piece in the layer, reduce the risk of fracture of the pole piece in the layer, and help the consistency of the winding layer in the layer, which is conducive to improving the overall consistency of the battery monomer. The two arc-shaped buffer members are arranged in different winding layers, which can buffer the stress generated in the electrode assembly from multiple aspects. Since the stress in the electrode assembly is a complex system, the stresses from different winding layers will superimpose and affect each other. By arranging the buffer members in different winding layers, the stress of each layer can be comprehensively buffered, the stress accumulation and transmission in the electrode assembly can be reduced, the entire electrode assembly can be better protected, and the overall reliability of the battery monomer can be improved.

[0024] In some embodiments of the present application, the buffer member is provided with a through hole. In this technical solution, when the buffer member is compressed by the first or second pole piece, the through hole can provide the space required for the compression deformation of the buffer member, which is conducive to making the buffer member more easily compressed, thereby improving the buffering effect of the buffer member and better absorbing the expansion. The through hole also helps to reduce the weight of the buffer member and the weight of the battery monomer, which is conducive to making the battery monomer have a higher volumetric energy density.

[0025] In some embodiments of the present application, the through hole is a plurality of through holes, and the plurality of through holes are arranged in an array on the buffer member. In this technical solution, the number of through holes is larger, which can further enhance the compressibility of the buffer member, improve the buffering effect of the buffer member, and further reduce the weight of the buffer member, thereby further improving the volumetric energy density of the battery monomer.

[0026] In some embodiments of the present application, the through hole is a plurality of through holes, and the plurality of through holes are arranged in an array on the buffer member. In this technical solution, the number of through holes is larger, which can further enhance the compressibility of the buffer member, improve the buffering effect of the buffer member, and further reduce the weight of the buffer member, thereby further improving the volumetric energy density of the battery monomer.

[0027] In some embodiments of the present application, along the winding axis, the size of the buffer member is greater than or equal to the size of the electrode assembly.

[0028] In the technical solution, in the winding axial direction, the size of the buffer member is greater than or equal to the size of the electrode assembly, the buffer member can fully cover the electrode assembly in the winding axial direction, thereby playing a more comprehensive buffering role on the first electrode plate or the second electrode plate in the winding layer, reducing the probability of local stress concentration of the first electrode plate or the second electrode plate at the position of the buffer member, and further reducing the risk of swelling and fracture of the outer electrode plate, thereby further improving the reliability of the battery cell.

[0029] In some embodiments of the present application, the thickness of the buffer member is T, where 0mm

[0030] In some embodiments of the present application, 0mm

[0031] In some embodiments of the present application, in the winding direction of the arc-shaped portion, the size of the buffer member is L2, where 0mm

[0032] In some embodiments of the present application, 2mm

[0033] In some embodiments of the present application, in the winding axial direction of the electrode assembly, the size of the buffer member is L3, where 0mm

[0034] In some embodiments of the present application, 50mm≤L3≤600mm. In this technical solution, by setting the size L3 of the buffer member in the above range, the buffer member can provide sufficient support and buffering effect, ensure the stability of the winding layer at the position of the buffer member, and also play a good buffering effect, which is conducive to relieving stress conditions and reducing the risk of expansion and fracture of the outer layer of the pole piece. Under this premise, the use of materials and weight of the buffer member can be balanced, the cost is reduced, and the battery monomer has a higher volumetric energy density.

[0035] In some embodiments of the present application, in the arc-shaped part, the second pole piece is a cathode piece, and the buffer member is arranged between the second pole piece and the isolation film.

[0036] In the above technical solution, since the first pole piece and the second pole piece in the winding layer will react chemically, if the buffer member is fixed on the first pole piece or the second pole piece, it is necessary to minimize the risk of affecting the chemical reaction between the first pole piece and the second pole piece by the fixing method. Therefore, the buffer member is more inclined to be fixed on the first pole piece or the second pole piece by the bonding method. Through the above scheme, the buffer member can be easily fixed on the cathode piece by the bonding method, which is conducive to improving the fixing reliability of the buffer member, thereby improving the buffering effect of the buffer member on the arc-shaped part, reducing the risk of stress concentration, and reducing the probability of expansion and fracture of the outer layer of the pole piece at the position of the arc-shaped part. Thus, the reliability of the battery monomer is improved.

[0037] In the second aspect, the embodiments of the present application also provide a battery device, which comprises the battery monomer according to any one of the preceding embodiments.

[0038] In the above technical solution, since the buffer member in the battery monomer can be arranged in at least one winding layer, the probability of fracture of the outer layer of the pole piece is reduced, and the reliability of the battery monomer as a whole is improved. Thus, the reliability of the battery device comprising the battery monomer is improved, the use performance of the battery device is improved, and the service life of the battery device is prolonged.

[0039] In the third aspect, the embodiments of the present application also provide a power consumption device, which comprises the battery monomer according to any one of the preceding embodiments, or the battery device according to the preceding embodiments, and the battery monomer or the battery device is used for storing or providing electric energy.

[0040] In the above technical solution, since the battery monomer and the battery device have high reliability, the power consumption device comprising the battery monomer or the battery device also has high reliability. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation to the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0042] Fig. 1 is a structural schematic diagram of a vehicle provided by some embodiments of the present application;

[0043] Fig. 2 is a structural exploded view of a battery device provided by some embodiments of the present application;

[0044] Fig. 3 is a schematic diagram of the internal structure of a battery cell provided by some embodiments of the present application;

[0045] Fig. 4 is a schematic diagram of the internal structure of a battery cell provided by some embodiments of the present application;

[0046] Fig. 5 is a schematic diagram of the assembly of an electrode assembly and a buffer provided by some embodiments of the present application;

[0047] Fig. 6 is a schematic diagram of the assembly of an electrode assembly and a buffer provided by some other embodiments of the present application;

[0048] Fig. 7 is a schematic diagram of the assembly between a buffer, an adhesive sheet and a first electrode provided by some embodiments of the present application;

[0049] Fig. 8 is a schematic diagram of the assembly of an electrode assembly and a buffer provided by some embodiments of the present application;

[0050] Fig. 9 is a schematic diagram of a buffer provided by some embodiments of the present application;

[0051] Fig. 10 is a schematic diagram of a buffer provided by some other embodiments of the present application;

[0052] Fig. 11 is a schematic diagram of a buffer provided by some other embodiments of the present application.

[0053] Fig. 11 is a schematic diagram of a buffer provided by some other embodiments of the present application. DETAILED DESCRIPTION

[0054] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0055] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used in the specification of the present application are only for the purpose of describing the specific embodiments of the present application and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification of the present application and the claims and the above description of drawings are intended to cover non-exclusive inclusion. The terms "first", "second" and the like in the specification of the present application and the claims or the above description of drawings are used to distinguish different objects, not to describe a particular order or primary and secondary relationship.

[0056] In the present application, the phrase "embodiments" means that the specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase appears at various places in the specification does not necessarily all refer to the same embodiments, nor is each embodiment mutually exclusive or alternative to the other embodiments.

[0057] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mount", "connect", "connection", "attach" should be understood broadly, for example, can be fixedly connected, can be detachably connected, or integrally connected; can be directly connected, or indirectly connected through an intermediate medium; can be internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0058] In the present application, the term "and / or" is only a description of the association relationship between the associated objects, which means that there can be three relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. In addition, the character " / " in the present application generally represents an "or" relationship between the associated objects before and after it.

[0059] In the embodiments of the present application, the same reference signs represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are only exemplary and should not constitute any limitation on the present application.

[0060] “Multiple” appearing in the present application means two or more (including two).

[0061] In the present application, the battery cell can include a lithium-ion battery, a sodium-ion battery, a sodium-lithium-ion battery, a lithium metal battery, a sodium metal battery, a lithium-sulfur battery, a magnesium-ion battery, a nickel-hydrogen battery, a nickel-cadmium battery, a lead-acid battery, etc., and the embodiments of the present application are not limited thereto. The battery cell can be in the shape of a cylinder, a flat body, a cuboid, or other shapes, etc., and the embodiments of the present application are not limited thereto. The battery cell is generally classified into three types according to the packaging method: cylindrical battery cells, square battery cells, and soft-pack battery cells, and the embodiments of the present application are not limited thereto.

[0062] The battery apparatus mentioned in the embodiments of the present application can refer to a device including 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. In some embodiments, the battery cell assembly is generally formed by arranging a plurality of battery cells.

[0063] As an example, the battery cell assembly can be a battery module formed by arranging and fixing a plurality of battery cells into one independent module. As an example, the battery module can be formed by bundling a plurality of battery cells with a cable tie.

[0064] In some embodiments, the battery apparatus can be a battery pack including a box and one or more battery cell assemblies accommodated in the box. As an example, the battery cell assembly can be a battery module, and the battery cell assembly can be accommodated in the box by fixing the battery module in the box. As an example, the battery cell assembly can also be accommodated in the box by directly fixing a plurality of battery cells in the box. The box can prevent liquid or other foreign matter from affecting the charging or discharging of the battery cells.

[0065] The battery cell includes a shell, an electrode assembly, and an electrolyte, the shell being used to accommodate the electrode assembly and the electrolyte. The electrode assembly is composed of a positive electrode tab, a negative electrode tab, and a separator film. The battery cell mainly relies on the movement of metal ions between the positive electrode tab and the negative electrode tab to work. The positive electrode tab includes a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer being coated on the surface of the positive electrode current collector, the positive electrode current collector without the positive electrode active material layer protruding from the positive electrode current collector with the positive electrode active material layer, and the positive electrode current collector without the positive electrode active material layer serving as a positive electrode tab. Taking a lithium ion battery as an example, the material of the positive electrode current collector can be aluminum, and the positive electrode active material can be lithium cobaltate, lithium iron phosphate, ternary lithium, or lithium manganate, etc. The negative electrode tab includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer being coated on the surface of the negative electrode current collector, the negative electrode current collector without the negative electrode active material layer protruding from the negative electrode current collector with the negative electrode active material layer, and the negative electrode current collector without the negative electrode active material layer serving as a negative electrode tab. The material of the negative electrode current collector can be copper, and the negative electrode active material can be carbon or silicon, etc. In order to ensure that no fusing occurs when passing a large current, the number of positive electrode tabs is multiple and stacked together, and the number of negative electrode tabs is multiple and stacked together.

[0066] The material of the separator film can be PP (polypropylene) or PE (polyethylene), etc. In addition, the electrode assembly can be a roll type structure or a laminated type structure, and the embodiments of the present application are not limited thereto.

[0067] In recent years, new energy vehicles have made a leap in development. In the field of electric vehicles, power batteries, as the power source of electric vehicles, play an irreplaceable important role. The battery is composed of a box body and a plurality of battery cells accommodated in the box body. Among them, the battery as a core part of new energy vehicles has high requirements in terms of safety and cycle life. However, in the winding core type battery cell, the tabs of the electrode assembly will swell during the cycle charging and discharging process, and the tabs will swell more severely as the cycle number increases. Therefore, the outer tabs are prone to be stretched and broken in the later cycle period. After the tabs are broken, on the one hand, it will cause problems such as capacity reduction, internal resistance increase, and voltage instability, affecting the performance of the battery cell; on the other hand, it will also increase the risk of thermal runaway and short circuit hazards, affecting the safety of the battery cell. That is, the swelling and breaking of the tabs inside the battery cell will affect the reliability of the battery cell.

[0068] In a general jelly-roll type battery cell, in order to alleviate the expansion of the electrode sheet inside the battery cell, a ring of silica gel pad is usually arranged outside the outer electrode sheet of the electrode assembly. However, since the electrode sheet of the electrode assembly is a multi-layer structure from inside to outside, the expansion of each layer of electrode sheet is accumulated and leads to the largest expansion of the outer electrode sheet, and the outer electrode sheet is more prone to expansion. Therefore, by arranging the silica gel pad outside the outer electrode sheet as described above, on the one hand, the accumulated expansion of the inner multi-layer electrode sheet of the electrode assembly still affects the expansion of the outer electrode sheet, and cannot effectively alleviate the problem of large expansion of the outer electrode sheet, thereby improving the reliability of the battery cell; on the other hand, arranging the silica gel pad outside the outer electrode sheet is not conducive to the silica gel pad entering the shell, which may increase the installation difficulty and is not conducive to the assembly of the battery cell, and may also lead to a large space occupied by the silica gel pad, affecting the volume energy density of the battery cell.

[0069] Based on the above considerations, in order to solve the problem that the electrode sheet is prone to expansion during the cycle process of the battery cell, and the outer electrode sheet of the electrode assembly is prone to breakage, affecting the reliability of the battery cell. The applicant designs a battery cell, which comprises: a shell assembly, an electrode assembly and a buffer, the electrode assembly is arranged in the shell assembly, and comprises a first electrode sheet, a second electrode sheet and a separator, the separator is arranged between the first electrode sheet and the second electrode sheet, the electrode assembly comprises a winding axis, the electrode assembly is a jelly-roll structure wound around the winding axis, and comprises a plurality of winding layers perpendicular to the winding axis, the winding layer comprises the first electrode sheet, the separator and the second electrode sheet arranged in layers; the buffer is arranged in at least one winding layer and located between the separator and the first electrode sheet, or located between the separator and the second electrode sheet.

[0070] In the battery cell with such a structure, since the buffer is arranged in at least one winding layer and located between the separator and the first electrode sheet, or located between the separator and the second electrode sheet, the buffer can play a buffering role between the outer electrode sheet and the inner electrode sheet of the electrode assembly, and can provide expansion force release space for the inner electrode sheet and the outer electrode sheet at the same time, effectively alleviate the situation that the expansion force of the inner electrode sheet is accumulated to the outer electrode sheet, and is conducive to reducing the tensile force acting on the outer electrode sheet, reducing the probability of breakage of the outer electrode sheet, and improving the reliability of the battery cell. Moreover, since the buffer is arranged in the winding layer, the buffer can be assembled into the shell together with the electrode assembly, which can make the assembly of the buffer in the battery cell simpler and reduce the overall assembly difficulty of the battery cell.

[0071] The battery cell and the battery device disclosed in the embodiments of the present application can be used in, but not limited to, an electric device such as a vehicle, a ship or an aircraft. The power supply system of the electric device can be composed of the battery cell and the battery device disclosed in the present application, which is conducive to improving the application range of the battery cell and the battery device.

[0072] The embodiments of the present application provide a power consumption device using a battery device as a power supply. The power consumption device can be, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric automobile, a ship, a spacecraft, and the like. The electric toy can include a fixed or mobile electric toy, such as a game console, an electric automobile toy, an electric ship toy, an electric aircraft toy, and the like. The spacecraft can include an airplane, a rocket, a space shuttle, a spacecraft, and the like.

[0073] The following embodiments are described by taking a power consumption device 1000 of an embodiment of the present application as an example of a vehicle for convenience of description. Please refer to FIG. 1, which is a structural schematic diagram of a vehicle provided by some embodiments of the present application. The vehicle can be a fuel automobile, a gas automobile, or a new energy automobile. The new energy automobile can be a pure electric automobile, a hybrid electric automobile, or a range extended automobile. The vehicle is internally provided with a battery device 100. The battery device 100 can be arranged at the bottom, the head, or the tail of the vehicle. The battery device 100 can be used for power supply of the vehicle, for example, the battery device 100 can be used as an operating power supply of the vehicle. The vehicle can further include a controller 200 and a motor 300. The controller 200 is used to control the battery device 100 to supply power to the motor 300, for example, to meet the working power demand of the vehicle during starting, navigation, and driving.

[0074] In some embodiments of the present application, the battery device 100 can not only be used as an operating power supply of the vehicle, but also be used as a driving power supply of the vehicle, to replace or partially replace fuel or natural gas to provide driving power for the vehicle.

[0075] Please refer to FIG. 2, which is an exploded structural diagram of the battery device 100 provided by some embodiments of the present application. The battery device 100 includes a box body 10 and a plurality of battery monomers 20. The battery monomers 20 are arranged in the box body 10. The box body 10 is used to provide an assembly space for the battery monomers 20. The box body 10 can adopt various structures. In some embodiments, the box body 10 can include a first box body 11 and a second box body 12. The first box body 11 and the second box body 12 are overlapped with each other. The first box body 11 and the second box body 12 jointly define an assembly space for accommodating the battery monomers 20. The second box body 12 can be a hollow structure with one end open. The first box body 11 can be a plate structure. The first box body 11 is overlapped with the open side of the second box body 12, so that the first box body 11 and the second box body 12 jointly define the assembly space. The first box body 11 and the second box body 12 can also be hollow structures with one side open. The open side of the first box body 11 is overlapped with the open side of the second box body 12. Of course, the box body 10 formed by the first box body 11 and the second box body 12 can have various shapes, such as a cylinder, a cuboid, and the like.

[0076] In the battery device 100, the plurality of battery cells 20 can be connected in series, in parallel, or in a mixed connection, where the mixed connection means that the plurality of battery cells 20 are connected in series and in parallel. The plurality of battery cells 20 can be directly connected in series, in parallel, or in a mixed connection, and the plurality of battery cells 20 are accommodated in the case 10 as a whole. Alternatively, the plurality of battery cells 20 can be connected in series, in parallel, or in a mixed connection to form a battery module, and the plurality of battery modules are connected in series, in parallel, or in a mixed connection to form a whole, which is accommodated in the case 10. The battery device 100 can further include other structures, for example, the battery device 100 can further include a current collecting member for electrically connecting the plurality of battery cells 20.

[0077] Referring to FIG. 2, FIG. 2 is an exploded view of the structure of the battery device 100 according to some embodiments of the present application. The battery device 100 includes a plurality of rows of battery cells 20, which are arranged along the length direction of the case 10. Each row of battery cells 20 includes a plurality of battery cells 20 arranged along the width direction of the case 10. Alternatively, the plurality of rows of battery cells 20 are arranged along the width direction of the case 10, and each row of battery cells 20 includes a plurality of battery cells 20 arranged along the length direction of the case 10.

[0078] Each battery cell 20 can be a secondary battery or a primary battery. The secondary battery refers to a battery cell 20 that can be activated by charging after discharging. The secondary battery can be a lithium ion battery, a sodium ion battery, a sodium-lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium-sulfur battery, a magnesium ion battery, a nickel-hydrogen battery, a nickel-cadmium battery, a lead-acid battery, or the like. The embodiments of the present application are not limited in this regard. The battery cell 20 can have a cylindrical shape, a flat shape, a cuboid shape, or other shapes. For example, in FIG. 2, the battery cell 20 has a cuboid shape.

[0079] According to some embodiments of the present application, referring to FIGS. 3, 4, and 5, a battery cell 20 is provided, which includes a housing assembly 21, an electrode assembly 22, and a buffer 23. The electrode assembly 22 is arranged in the housing assembly 21 and includes a first electrode sheet 221, a second electrode sheet 222, and a separator 223 arranged between the first electrode sheet 221 and the second electrode sheet 222. The electrode assembly 22 includes a winding axis, and the electrode assembly 22 has a winding core structure wound around the winding axis and includes a plurality of winding layers perpendicular to the winding axis. The winding layers include the first electrode sheet 221, the separator 223, and the second electrode sheet 222 arranged in layers. The buffer 23 is arranged in at least one winding layer and located between the separator 223 and the first electrode sheet 221, or between the separator 223 and the second electrode sheet 222.

[0080] The shell assembly 21 can refer to a component that houses the electrode assembly 22 and the electrolyte, and protects the electrode assembly 22 and the electrolyte inside. As an example, referring to FIG. 3, the shell assembly 21 can include, but is not limited to, a shell 211 and a cover plate 212, etc., wherein the shell 211 and the cover plate 212 can be, but are not limited to, metal or plastic, etc., the metal material can be, but is not limited to, steel or aluminum, etc., and the plastic material can be, but is not limited to, polycarbonate, polypropylene, etc.

[0081] The electrode assembly 22 can be explained as above, and will not be explained in detail here. Among them, one of the first electrode sheet 221 and the second electrode sheet 222 can refer to an anode sheet, and the other can refer to a cathode sheet. As an example, the first electrode sheet 221 can be an anode sheet, and the second electrode sheet 222 can be a cathode sheet.

[0082] The electrode assembly 22 includes a winding axial direction, and the electrode assembly 22 is wound into a roll core around the winding axial direction. It can be understood that the electrode assembly 22 mentioned in the embodiments of the present application is a roll core, and the winding axial direction can refer to a direction perpendicular to the winding plane of the roll core. As an example, referring to FIG. 3, the winding axial direction can refer to the third direction Z of FIG. 3.

[0083] In the electrode assembly 22 of the embodiments of the present application, during the winding process, the first electrode sheet 221, the second electrode sheet 222 and the separator film 223 of each layer are wound together to form a winding layer. From the inside to the outside, there can be a layer of first electrode sheet 221 first, then a separator film 223, and then a second electrode sheet 222. The three layers together constitute a basic winding layer, and the electrode assembly 22 often includes multiple winding layers arranged from the inside to the outside.

[0084] The buffer 23 can refer to a component that can deform to absorb energy when subjected to external force. When the first electrode sheet 221 and / or the second electrode sheet 222 expands, the buffer 23 can absorb the expansion force by deforming and provide the space required for the expansion of the first electrode sheet 221 or the second electrode sheet 222, thereby playing a buffering role. Alternatively, the buffer 23 can refer to a structure or component that can be compressed and restore to its original state after the external force is removed. Among them, the buffer 23 can be, but is not limited to, a polypropylene material, a polyethylene material, foam, a silicone piece or a rubber piece, etc. As an example, referring to FIG. 9, the buffer 23 can be a foam sheet.

[0085] The "buffering member 23 is arranged in at least one winding layer" can be understood as the buffering member 23 being arranged in one winding layer, or being arranged in two, three or more winding layers. When the buffering member 23 is arranged in multiple winding layers, the buffering member 23 can be arranged in the outermost winding layer, in the middle winding layer, in the innermost winding layer, between the outermost winding layer and the middle winding layer, between the middle winding layer and the innermost winding layer, and the like, which is not limited herein.

[0086] The buffering member 23 can be arranged between the separation film 223 and the first tab 221 of each winding layer, or between the separation film 223 and the second tab 222, which is not limited herein. As an example, referring to FIG. 5 and FIG. 6, the buffering member 23 can be arranged between the separation film 223 and the second tab 222.

[0087] It should be noted that in the above embodiment, the cross-sectional shape of the winding core of the electrode assembly 22 can be, but is not limited to, a cylindrical shape, a racetrack shape, a rectangular shape, and the like, and accordingly, the shape of the housing assembly 21 can be, but is not limited to, a cylindrical shell, a square shell, and the like, which is not limited herein.

[0088] According to the foregoing analysis, since the electrode assembly 22 is in the form of a winding core, according to its shape, the electrode assembly 22 generally includes an arc-shaped portion 2012 and a non-arc-shaped portion (e.g., a flat portion 2011), and in the above embodiment, the buffering member 23 can be arranged in the winding layer at the position of the arc-shaped portion 2012, or in the winding layer at the position of the non-arc-shaped portion, or in the winding layer at the positions of both the arc-shaped portion 2012 and the non-arc-shaped portion, which is not limited herein.

[0089] During the cyclic expansion process of the electrode assembly 22, the first tab 221 and / or the second tab 222 will expand, and as the number of cycles increases, the first tab 221 and / or the second tab 222 will expand more severely, eventually causing the electrode assembly 22 to tightly adhere to the shell wall of the housing 211 at both ends of the second direction Y (see FIG. 4), at which time a tensile force f1 (see FIG. 4) will be formed on the first tab 221 and / or the second tab 222, especially in the outermost first tab 221 and / or the outermost second tab 222, which will be more obvious and more prone to risk of expansion rupture.

[0090] In the technical solution, the buffer member 23 is arranged in the at least one winding layer and located between the isolation film 223 and the first pole piece 221 or between the isolation film 223 and the second pole piece 222, so that the buffer member 23 can bear the buffering effect between the outer pole piece and the inner pole piece of the electrode assembly 22, can provide the space required for expansion of the inner pole piece and the outer pole piece at the same time, effectively alleviates the situation that the expansion force of the inner pole piece is accumulated to the outer pole piece, is beneficial to reducing the tensile force of the outer pole piece, thereby reducing the probability of fracture of the outer pole piece and improving the reliability of the battery monomer 20. Moreover, since the buffer member 23 is arranged in the winding layer, when the electrode assembly 22 is assembled into the shell, the buffer member 23 can be assembled into the shell together with the electrode assembly 22, so that the assembly of the buffer member 23 in the battery monomer 20 is simpler, and the assembly difficulty of the whole battery monomer 20 is reduced.

[0091] In some embodiments of the present application, referring to FIGS. 3, 5 and 6, the electrode assembly 22 includes the main body part 201 and the tab 202 connected to each other, the main body part 201 includes the flat part 2011 and the arc-shaped part 2012 connected to each other, and the buffer member 23 is arranged on the arc-shaped part 2012.

[0092] The tab 202 can refer to a metal structural member in the electrode assembly 22 for leading out current. Referring to the above, in the electrode assembly 22, the first pole piece 221 in the plurality of winding layers can partially extend and gather to form the tab 202, and the second pole piece 222 in the plurality of winding layers can also partially extend and gather to form another tab 202. According to the different polarities of the first pole piece 221 and the second pole piece 222, the polarities of the tabs 202 formed by the two are also different. As an example, the first pole piece 221 can be an anode piece, and correspondingly, the first pole piece 221 forms a negative tab; the second pole piece 222 can be a cathode piece, and correspondingly, the second pole piece 222 forms a positive tab.

[0093] The main body part 201 can refer to the main structure of the electrode assembly 22 which does not include the tab 202.

[0094] The main body part 201 includes the flat part 2011 and the arc-shaped part 2012 connected to each other, which can be understood as that the main body part 201 can have a flat structure and an arc-shaped part. Among them, the flat part 2011 can be connected to the arc-shaped part 2012 at one end, or connected to the arc-shaped part 2012 at both ends, which is not specifically limited here.

[0095] For example, referring to FIG. 5 and FIG. 6, the shape of the main body 201 in the cross section perpendicular to the winding axis direction can be a racetrack shape, the flat portion 2011 extends along the first direction X, and the arc-shaped portion 2012 is arranged at both ends of the first direction X. For another example, the shape of the main body 201 in the cross section perpendicular to the winding axis direction can also be a rectangle, and the arc-shaped portion 2012 is arranged at the four corners of the rectangle, and the flat portion 2011 is arranged at the four edges of the rectangle.

[0096] In the above technical solution, since the arc-shaped portion 2012 of the main body 201 is an arc-shaped structure and has a curvature change, stress concentration phenomenon is more likely to occur during the cyclic expansion of the electrode assembly 22, and the expansion tensile force borne by the arc-shaped portion 2012 is larger than that borne by other positions of the main body 201. By arranging the buffer 23 on the arc-shaped portion 2012, when the first electrode tab 221 and / or the second electrode tab 222 corresponding to the position of the arc-shaped portion 2012 expands, the buffer 23 can be compressed to absorb energy, reduce the expansion tensile force, and provide space required for the expansion of the first electrode tab 221 and / or the second electrode tab 222, which is conducive to reducing the risk of electrode tab fracture at the position of the arc-shaped portion 2012, and thus can reduce the probability of overall expansion fracture of the electrode assembly 22, and improve the reliability of the battery monomer 20. Since the buffer 23 is arranged on the arc-shaped portion 2012, the setting area of the buffer 23 on the main body 201 can be reduced, the material can be saved, the cost can be reduced, the volume of the buffer 23 can be reduced, the internal space of the shell assembly 21 can be saved, and the weight of the buffer 23 can be reduced, thereby reducing the overall weight of the battery monomer 20, and thus improving the volume energy density of the battery monomer 20.

[0097] Further, referring to FIG. 5 and FIG. 6, when the buffer 23 is arranged on the arc-shaped portion 2012, the cross section of the buffer 23 perpendicular to the winding axis direction can be arc-shaped, and the thickness of the arc-shaped portion gradually decreases from the middle to both ends. In this way, the buffer 23 can adapt to the arc-shaped structure of the arc-shaped portion 2012, reduce the probability of the occurrence of bending positions between the first electrode tab 221 or the second electrode tab 222 in the winding layer at the position of the arc-shaped portion 2012, and thus reduce the risk of stress concentration, which is conducive to improving the buffering effect of the buffer 23, improving the reliability of the electrode assembly 22, and thus improving the reliability of the battery monomer 20.

[0098] In some embodiments of the present application, the buffer 23 is bonded to the first electrode tab 221 or the second electrode tab 222.

[0099] With reference to the foregoing, the buffer piece 23 can be arranged between the first tab 221 and the isolation film 223, and in this case, the buffer piece 23 can be bonded to the first tab 221; the buffer piece 23 can also be arranged between the second tab 222 and the isolation film 223, and in this case, the buffer piece 23 can be bonded to the second tab 222. In the above technical solution, no specific limitation is made herein.

[0100] In the above technical solution, by bonding the buffer piece 23 to the first tab 221 or the second tab 222, the buffer piece 23 can be fixed on the first tab 221 or the second tab 222, which is conducive to reducing the risk of displacement of the buffer piece 23 during the winding process of the electrode assembly 22, and reducing the probability of the buffer piece 23 deviating from the position of the arc-shaped portion 2012, thereby improving the stability of the buffer piece 23 in the electrode assembly 22, improving the buffering and swelling fracture inhibition effect of the buffer piece 23 on the outermost tab of the electrode assembly 22, and further improving the reliability of the battery monomer 20.

[0101] In some embodiments of the present application, with reference to FIGS. 5, 6 and 7, an end surface of the buffer piece 23 facing the isolation film 223 is provided with a bonding piece 24, and in the winding direction F1 of the arc-shaped portion 2012, both ends of the bonding piece 24 exceed the buffer piece 23 and are bonded to the first tab 221 or the second tab 222.

[0102] The bonding piece 24 can refer to a sheet-shaped component with bonding function. The material of the bonding piece 24 can be, but is not limited to, organic polymer or rubber, etc. The organic polymer can include, but is not limited to, acrylate, polyurethane, etc. The rubber can include, but is not limited to, natural rubber or synthetic rubber, etc. As an example, the bonding piece 24 can be an adhesive tape.

[0103] “Both ends of the bonding piece 24 exceed the buffer piece 23” can be understood as, in the winding direction F1, the size of the bonding piece 24 is greater than the size of the buffer piece 23, and both ends of the bonding piece 24 protrude relative to both ends of the buffer piece 23.

[0104] “Bonding piece 24 is bonded to the first tab 221 or the second tab 222” can be understood as, when the buffer piece 23 is arranged between the first tab 221 and the isolation film 223, the bonding piece 24 is bonded to the first tab 221 (see FIG. 7); when the buffer piece 23 is arranged between the second tab 222 and the isolation film 223, the bonding piece 24 is bonded to the second tab 222. Alternatively, the buffer piece 23 can be fixed on the first tab 221 or the second tab 222 only through the bonding piece 24. Further, the buffer piece 23 can also be bonded to the first tab 221 or the second tab 222, and then be fixed on the first tab 221 or the second tab 222 through the bonding piece 24.

[0105] In the technical solution, the bonding piece 24 is a separate component and can be produced in batches, which is conducive to ensuring controllable bonding and making the bonding force more uniform when the bonding piece 24 is bonded to the first pole piece 221 or the second pole piece 222, improving the reliability of fixing the buffer piece 23 on the first pole piece 221 or the second pole piece 222, and the fixing method is relatively simple and easy to operate, which is conducive to improving the assembly efficiency. In addition, the buffer piece 23 can be fixed on the first pole piece 221 or the second pole piece 222 through the bonding piece 24 on the basis of being bonded to the first pole piece 221 or the second pole piece 222, which can further improve the installation reliability of the buffer piece 23, reduce the risk of the buffer piece 23 separating from the first pole piece 221 or the second pole piece 222, improve the buffering effect of the buffer piece 23 on the position of the arc-shaped part 2012, and further reduce the probability of swelling and fracture of the outermost pole piece.

[0106] In some embodiments of the present application, referring to FIG. 5, the buffer piece 23 is centrally arranged on the arc-shaped part 2012 in the winding direction F1 of the arc-shaped part 2012.

[0107] The winding direction F1 can be seen from FIG. 5, and the "buffer piece 23 is centrally arranged on the arc-shaped part 2012" can be understood as that the center of the buffer piece 23 is on the half-arc length dividing line of the arc-shaped part 2012 (see FIG. 5 for details).

[0108] In the technical solution, the arc-shaped part 2012 of the electrode assembly 22 has a problem of stress concentration at the position itself, and the middle position of the arc-shaped part 2012 is a relatively large stress point. The buffer piece 23 is centrally arranged on the arc-shaped part 2012, thereby targetedly relieving the stress concentration phenomenon of the arc-shaped part 2012, which is conducive to better absorbing and dispersing stress by the buffer piece 23 and reducing the stress size borne by the middle position of the arc-shaped part 2012. In addition, the buffer piece 23 is centrally arranged on the arc-shaped part 2012, which is also conducive to balancing the stress distribution inside the entire electrode assembly 22, can diffuse the stress originally concentrated in the middle position of the arc-shaped part 2012 to the periphery, makes the stress of each part of the electrode assembly 22 more uniform, thereby reducing the risk of swelling and fracture of the outer pole piece caused by local large stress, and is conducive to improving the reliability of the electrode assembly 22 and further improving the overall reliability of the battery monomer 20.

[0109] In some embodiments of the present application, referring to FIG. 8, in the winding direction F1 of the arc-shaped part 2012, the size of the winding layer of the arc-shaped part 2012 where the buffer piece 23 is arranged is L1, and the size of the buffer piece 23 is L2, wherein 0

[0110] It can be understood that L2 / L1 can be, but is not limited to, 0.1%, 0.5%, 1%, 1.5%, 5%, 10%, 12%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 98%, 99%, and the like.

[0111] In the technical solution, by setting the ratio of the size L2 of the buffer piece 23 to the size L1 of the winding layer of the buffer piece 23 arranged in the arc-shaped portion 2012 within the range, the size of the buffer piece 23 does not exceed the size of the winding layer of the buffer piece 23 arranged in the arc-shaped portion 2012, so that the buffer piece 23 cannot extend to the flat portion 2011, and the risk that the first pole piece 221 or the second pole piece 222 is broken due to stress concentration caused by the bending position between the buffer piece 23 and the first pole piece 221 or the second pole piece 222 when the buffer piece 23 is in the flat portion 2011 can be reduced, and the reliability of the electrode assembly 22 when the buffer piece 23 is arranged in the winding layer can be improved. Since the buffer piece 23 does not extend to the flat portion 2011, the volume of the buffer piece 23 can be reduced, the space can be saved, and the weight of the buffer piece 23 can be reduced, and thus the overall weight of the battery monomer 20 can be reduced, and the volume energy density of the battery monomer 20 can be improved.

[0112] In some embodiments of the present application, referring to FIG. 6, a plurality of buffer pieces 23 are arranged on the arc-shaped portion 2012, and the plurality of buffer pieces 23 are arranged at intervals in the winding direction F1 of the arc-shaped portion 2012 and symmetrically arranged.

[0113] The number of the buffer pieces 23 arranged on the arc-shaped portion 2012 can be, but is not limited to, two, three, four, and the like. For example, referring to FIG. 6, two buffer pieces 23 can be arranged on the arc-shaped portion 2012.

[0114] In the technical solution, the volume of the buffer piece 23 can be further reduced by using the above-mentioned scheme, so that the space can be further saved, the volume ratio of the electrode assembly 22 in the shell assembly 21 can be improved, and the weight of the buffer piece 23 can be further reduced, and thus the overall weight of the battery monomer 20 can be reduced, and the volume energy density of the battery monomer 20 can be further improved.

[0115] In some embodiments of the present application, referring to FIG. 6, in the winding direction F1 of the arc-shaped portion 2012, the buffer piece 23 has a center face, two buffer pieces 23 are arranged on the arc-shaped portion 2012, and the center face of the buffer piece 23 and the quarter division line 2012a of the arc length of the arc-shaped portion 2012 are close to or coincide with each other.

[0116] The "center surface of the buffer 23" can refer to a surface that equally divides the buffer 23 in the winding direction F1. Referring to FIG. 5, the center surface of the buffer 23 coincides with the quarter division line 2012a of the arc length of the arc-shaped portion 2012.

[0117] The "quarter division line 2012a of the arc length of the arc-shaped portion 2012" can refer to a division line that cuts off a quarter length of the arc length of the arc-shaped portion 2012 from the end of the arc-shaped portion 2012.

[0118] "Proximity or coincidence of the center surface of the buffer 23 and the quarter division line 2012a of the arc length of the arc-shaped portion 2012" can be understood as the center surface of the buffer 23 being arranged next to the quarter division line 2012a of the arc length of the arc-shaped portion 2012, or the center surface of the buffer 23 coinciding with the quarter division line 2012a of the arc length of the arc-shaped portion 2012, i.e., the quarter division line 2012a of the arc length of the arc-shaped portion 2012 is located on the center surface of the buffer 23.

[0119] In the above technical solution, the quarter division line 2012a of the arc length of the arc-shaped portion 2012 is located close to the edge positions of the two ends of the arc-shaped portion 2012, and the edge positions of the two ends of the arc-shaped portion 2012 are key points for stress dispersion. By arranging the center surface of the buffer 23 close to or coinciding with the quarter division line 2012a, the buffer 23 can better adapt to the direction of stress transmission, disperse the stress to a wider area, and reduce the degree of local stress concentration. When the electrode assembly 22 is bent and deformed, the two end positions of the arc-shaped portion 2012 first bear the bending stress. The above solution can effectively absorb and buffer the bending stress, reduce the risk of damage to the internal structure of the electrode assembly 22 due to excessive bending, improve the reliability of the electrode assembly 22, and further improve the overall reliability of the battery monomer 20. Moreover, the above solution can also make the first electrode sheet 221 or the second electrode sheet 222 form a certain gap at the middle position of the arc-shaped portion 2012 in the winding layer where the buffer 23 is located (see FIG. 6), which can provide the space required for the expansion of the middle position of the arc-shaped portion 2012, and is also conducive to reducing the probability of stress concentration at the middle position of the arc-shaped portion 2012, and can improve the reliability of the battery monomer 20.

[0120] On the other hand, since the arc-shaped portion 2012 has an arc-shaped structure and the shell assembly 21 generally has a square shape, a gap is formed between the arc-shaped portion 2012 and the shell assembly 21 at both ends of the winding direction F1. By making the center surface of the two buffer members 23 and the quarter division line 2012a of the arc length of the arc-shaped portion 2012 close to or coincide with each other, the gap formed between the arc-shaped portion 2012 and the shell assembly 21 can be fully utilized to arrange the buffer members 23, the probability of increasing the size of the electrode assembly 22 in the first direction X and the second direction Y due to the arrangement of the buffer members 23 in the winding layer (see FIG. 6) can be reduced, the space ratio of the electrode assembly 22 in the shell assembly 21 can be improved, and the battery monomer 20 can have a higher volumetric energy density.

[0121] In some embodiments of the present application, referring to FIGS. 5 and 6, the opposite ends of the flat portion 2011 are provided with arc-shaped portions 2012, and the two arc-shaped portions 2012 are each provided with a buffer member 23.

[0122] Referring to FIGS. 5 and 6, the opposite ends of the flat portion 2011 can refer to the two ends along the first direction X. The opposite ends of the flat portion 2011 are provided with arc-shaped portions 2012, so that the cross-sectional shape of the electrode assembly 22 perpendicular to the winding axis direction is a racetrack shape, and such a winding core structure is relatively simple.

[0123] In the above technical solution, the two arc-shaped portions 2012 are each provided with a buffer member 23, the buffer member 23 can provide a space required for expansion for the arc-shaped portion 2012 at each of the opposite ends of the flat portion 2011, the two buffer members 23 can collectively provide a larger expansion release space, and can also provide a buffer effect and a space required for expansion in time for each arc-shaped portion 2012 when it expands, which can reduce the risk of expansion rupture of the outer electrode sheet at the position of the arc-shaped portion 2012, further improve the reliability of the electrode assembly 22, and further improve the reliability of the battery monomer 20.

[0124] In some embodiments of the present application, the buffer members 23 of the two arc-shaped portions 2012 are arranged in the same winding layer, or are arranged in different winding layers.

[0125] In the technical solution, the two arc-shaped buffer members 23 are arranged in the same winding layer, so that the buffer members 23 can buffer the stress generated in the layer, can timely absorb and disperse the stress, effectively reduce the risk of stress concentration in a local area, better protect the first or second pole piece 221 or 222 in the layer, reduce the risk of fracture of the pole piece in the layer, and help the consistency of the winding layer, and help improve the overall consistency of the battery monomer 20. The two arc-shaped buffer members 23 are arranged in different winding layers, which can buffer the stress generated in the electrode assembly 22 from multiple aspects. Since the stress inside the electrode assembly 22 is a complex system, the stresses from different winding layers will superimpose and affect each other. By arranging the buffer members 23 in different winding layers, the stress of each layer can be comprehensively buffered, the stress accumulation and transmission inside the electrode assembly 22 can be reduced, the entire electrode assembly 22 can be better protected, and the overall reliability of the battery monomer 20 can be improved.

[0126] In some embodiments of the present application, referring to FIGS. 10 and 11, the buffer member 23 is provided with a through hole 23a.

[0127] The through hole 23a can refer to a hole that penetrates the buffer member 23 along the thickness direction of the buffer member 23. The shape of the through hole 23a can be, but is not limited to, a circular hole, a rectangular hole, a circular hole, or a long strip-shaped hole, and the like, which is not limited here.

[0128] In the technical solution, when the buffer member 23 is compressed by the first or second pole piece 221 or 222, the through hole 23a can provide the space required for the compression and deformation of the buffer member 23, which is conducive to making the buffer member 23 more easily compressed, thereby improving the buffering effect of the buffer member 23 and better absorbing the expansion. The through hole 23a also helps to reduce the weight of the buffer member 23 and the weight of the battery monomer 20, which is conducive to making the battery monomer 20 have a higher volumetric energy density.

[0129] In some embodiments of the present application, referring to FIG. 10, the through hole 23a is a plurality of through holes 23a, and the plurality of through holes 23a are arranged in an array on the buffer member 23.

[0130] The "plurality of through holes 23a arranged in an array on the buffer member 23" can be understood as that the plurality of through holes 23a are arranged in multiple rows along the second direction Y on the buffer member 23, and each row of through holes 23a is arranged in multiple along the third direction Z.

[0131] In the technical solution, the number of through holes 23a is larger, which can further enhance the compressibility of the buffer member 23, improve the buffering effect of the buffer member 23, and further reduce the weight of the buffer member 23, thereby further improving the volumetric energy density of the battery monomer 20.

[0132] In some embodiments of the present application, referring to FIG. 11, the through holes 23a are multiple and are long holes, and the multiple through holes 23a are arranged at intervals on the buffer 23 along the winding axis or a direction perpendicular to the winding axis.

[0133] Referring to FIG. 11, the winding axis can refer to the third direction Z of FIG. 11, and the direction perpendicular to the winding axis can be the second direction Y. That is, the through holes 23a can be long holes extending along the second direction Y, and the multiple through holes 23a are arranged at intervals along the third direction Z; or the through holes 23a can be long holes extending along the third direction Z, and the multiple through holes 23a are arranged at intervals along the second direction Y (see FIG. 11).

[0134] In the above technical solution, the long hole has a larger size, can provide a larger space required for deformation for the buffer 23, and can make the buffer 23 more easily compressed, thereby improving the buffering effect of the buffer 23. Similarly, the long hole also has a better weight reduction effect on the buffer 23, which is beneficial to further improve the volumetric energy density of the battery monomer 20.

[0135] In some embodiments of the present application, along the winding axis, the size of the buffer 23 is greater than or equal to the size of the electrode assembly 22.

[0136] Referring to the foregoing description, the winding axis can be the third direction Z of FIG. 3, FIG. 9 to FIG. 11, that is, it can be understood as the height direction of the electrode assembly 22. “The size of the buffer 23 is greater than or equal to the size of the electrode assembly 22” can be understood as, along the winding axis, the size of the buffer 23 can be greater than the size of the electrode assembly 22, or the size of the buffer 23 is equal to the size of the electrode assembly 22.

[0137] In the above technical solution, along the winding axis, whether the size of the buffer 23 is greater than the size of the electrode assembly 22 or equal to the size of the electrode assembly 22, the buffer 23 can fully cover the electrode assembly 22 in the winding axis, thereby playing a more comprehensive buffering role on the first or second electrode sheet 221 in the winding layer, which can reduce the probability of local stress concentration of the first or second electrode sheet 221 at the position of the buffer 23, thereby reducing the risk of swelling and fracture of the outer electrode sheet, and is beneficial to further improve the reliability of the battery monomer 20.

[0138] In some embodiments of the present application, referring to FIG. 7, the thickness of the buffer 23 is T, wherein 0mm < T ≤ 100mm.

[0139] T can be, but is not limited to, 0.2 mm, 0.4 mm, 0.7 mm, 0.8 mm, 1 mm, 2 mm, 5 mm, 8 mm, 12 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, 75 mm, 80 mm, 85 mm, 90 mm, 95 mm, 99 mm, 100 mm, and the like.

[0140] It can be understood that the thickness T of the buffer piece 23 can be selected to a corresponding thickness value according to the size of the electrode assembly 22. Generally, the thickness T of the buffer piece 23 is not more than 100 mm. If the thickness T of the buffer piece 23 exceeds 100 mm, the buffer piece 23 will have a better buffering effect while causing material waste and occupying a larger space, thereby reducing the volumetric energy density of the battery monomer 20.

[0141] In the above technical solution, by setting the thickness T of the buffer piece 23 in the above range, the appropriate thickness range of the buffer piece 23 is determined, the difficulty of selecting the specification of the buffer piece 23 during production is reduced, so that the buffer piece 23 has a better buffering effect while balancing the amount of material and the occupied space, thereby reducing the cost and improving the volumetric energy density of the battery monomer 20.

[0142] In some embodiments of the present application, 0 mm < T ≤ 20 mm. In this embodiment, T can be, but is not limited to, 0.1 mm, 0.15 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 1.5 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm, 8.5 mm, 9 mm, 9.5 mm, 10 mm, 10.5 mm, 11 mm, 12.5 mm, 13.5 mm, 14 mm, 14.5 mm, 15.5 mm, 16 mm, 16.5 mm, 17 mm, 17.5 mm, 18 mm, 18.5 mm, 19 mm, 19.5 mm, and the like.

[0143] In the above technical solution, by further setting the thickness T of the buffer piece 23 in the above range, the thickness selection range of the buffer piece 23 can be reduced, the selection difficulty is reduced, and it is also beneficial to select a more appropriate range of the buffer piece 23.

[0144] In some embodiments of the present application, referring to FIG. 8, in the winding direction F1 of the arc-shaped portion 2012, the size of the buffer piece 23 is L2, where 0 mm < L2 ≤ 100 mm.

[0145] L2 can be, but is not limited to, 0.2 mm, 0.4 mm, 0.7 mm, 0.8 mm, 1 mm, 2 mm, 5 mm, 8 mm, 12 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, 75 mm, 80 mm, 85 mm, 90 mm, 95 mm, 99 mm, 100 mm, and the like.

[0146] It can be understood that, according to the size of the arc-shaped portion 2012 in the winding direction F1, the size L2 of the buffer 23 can be selected to a corresponding value. Generally, limited by the size of the electrode assembly 22 in the winding direction F1, the size L2 of the buffer 23 is not more than 100 mm. If the size L2 of the buffer 23 exceeds 100 mm, the buffer 23 will occupy a larger space, reducing the volumetric energy density of the battery cell 20.

[0147] In the above technical solution, by setting the size L2 of the buffer 23 in the above range, it is beneficial to determine the appropriate width range of the buffer 23, reduce the difficulty of selecting the specification of the buffer 23 during production, so that the buffer 23 has a better buffering effect while balancing the material usage and the occupied space, which is beneficial to reduce the cost and improve the volumetric energy density of the battery cell 20.

[0148] In some embodiments of the present application, 2 mm≤L2≤50 mm.

[0149] L2 can be, but is not limited to, 2 mm, 3 mm, 4 mm, 6 mm, 7 mm, 9 mm, 12 mm, 14 mm, 16 mm, 18 mm, 20 mm, 24 mm, 30 mm, 32 mm, 40 mm, 45 mm, 48 mm, 50 mm, and the like. If L2 is less than 2 mm, the width size of the buffer 23 in the winding direction F1 is small, which cannot have a good buffering effect, and the role of relieving stress concentration is not obvious. If L2 is greater than 50 mm, the width size of the buffer 23 in the winding direction F1 is large, which can have a good buffering effect while easily leading to a large size and occupying a large space, and also increases the material usage, which is not conducive to reducing the cost and improving the volumetric energy density of the battery cell 20.

[0150] In the above technical solution, by further narrowing the value range of the size L2 of the buffer 23, the difficulty of selecting the size L2 of the buffer 23 can be reduced, which is beneficial to select a more appropriate range of the buffer 23.

[0151] In some embodiments of the present application, with reference to FIGS. 3 and 9, in the winding axial direction of the electrode assembly 22, the size of the buffer 23 is L3, wherein 0 mm

[0152] The winding axial direction of the electrode assembly 22 can refer to the third direction Z of FIG. 3, and the size L3 of the buffer member 23 can refer to FIG. 9. In the above implementation, L3 can be, but is not limited to, 1 mm, 5 mm, 10 mm, 15 mm, 20 mm, 30 mm, 50 mm, 80 mm, 120 mm, 150 mm, 200 mm, 220 mm, 240 mm, 300 mm, 320 mm, 350 mm, 400 mm, 420 mm, 500 mm, 560 mm, 600 mm, 650 mm, 700 mm, 750 mm, 800 mm, 850 mm, 900 mm, 950 mm, 980 mm, 1000 mm, 1100 mm, 1150 mm, 1200 mm, and the like. It can be understood that, according to the size of the electrode assembly 22 in the winding axial direction, the size L3 of the buffer member 23 can be selected to a corresponding value, but generally will not exceed 1200 mm, otherwise it is easy to cause the buffer member 23 to have a large size, resulting in excessive use of materials.

[0153] In the above technical solution, by setting the size L3 of the buffer member 23 in the winding axial direction of the electrode assembly 22 within the above range, the range of the size L3 of the buffer member 23 is determined, the difficulty of selecting the specification of the buffer member 23 during production is reduced, the production difficulty is reduced, and the cost is reduced.

[0154] In some embodiments of the present application, 50 mm≤L3≤600 mm.

[0155] L3 can be, but is not limited to, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, 150 mm, 160 mm, 170 mm, 180 mm, 190 mm, 200 mm, 210 mm, 220 mm, 230 mm, 240 mm, 250 mm, 260 mm, 270 mm, 280 mm, 290 mm, 300 mm, 320 mm, 340 mm, 350 mm, 360 mm, 380 mm, 400 mm, 420 mm, 460 mm, 500 mm, 520 mm, 540 mm, 560 mm, 580 mm, 600 mm, and the like. It can be understood that, if L3 is less than 50 mm, the size L3 of the buffer member 23 is small, which cannot play a sufficient supporting and buffering role, is not conducive to ensuring the stability of the winding layer at the position of the buffer member 23, and cannot play a good buffering role, which is not conducive to relieving stress; if L3 is greater than 600 mm, the size L3 of the buffer member 23 is large, which is easy to cause the buffer member 23 to have an excessive performance, resulting in waste of materials, and further causing the overall weight of the battery monomer 20 to be large, which is not conducive to improving the volume energy density of the battery monomer 20.

[0156] In the technical solution, the size L3 of the buffer member 23 is set within the range, so that the buffer member 23 can provide sufficient support and buffering effect, ensure the stability of the winding layer at the position of the buffer member 23, and also play a good buffering effect, which is conducive to relieving stress and reducing the risk of expansion and fracture of the outer layer of the pole piece. On the premise, the use of materials and weight of the buffer member 23 can be balanced, the cost is reduced, and the battery monomer 20 has a higher volume energy density.

[0157] In some embodiments of the application, in the arc-shaped part 2012, the second pole piece 222 is a cathode piece, and the buffer member 23 is arranged between the second pole piece 222 and the isolation film 223.

[0158] It can be understood that, due to the different material properties of the cathode piece and the anode piece, the cathode piece (positive pole piece) is usually composed of a positive active material, a conductive agent and a binder, coated on a current collector (usually an aluminum foil), and the binder used by the cathode piece is usually easier to interact between the adhesive and the like, which is conducive to the adhesion of the buffer member 23. Moreover, the active material and the conductive agent of the cathode piece have a relatively uniform particle distribution, and the surface is relatively flat, so that the contact surface between the buffer member 23 and the cathode piece is larger, which is conducive to the better filling of the adhesive and the like in the gap between the buffer member 23 and the cathode piece. That is, the second pole piece 222 is a cathode piece, which can facilitate the fixation of the buffer member 23 on the second pole piece 222 by adhesion.

[0159] In the technical solution, since the first pole piece 221 and the second pole piece 222 in the winding layer will react chemically, if the buffer member 23 is fixed on the first pole piece 221 or the second pole piece 222, it is necessary to minimize the risk of affecting the chemical reaction between the first pole piece 221 and the second pole piece 222 by the fixing method, so that the buffer member 23 is more inclined to be fixed on the first pole piece 221 or the second pole piece 222 by adhesion. Through the above-mentioned scheme, the buffer member 23 can be easily fixed on the cathode piece by adhesion, which is conducive to improving the fixing reliability of the buffer member 23, and further improving the buffering effect of the buffer member 23 on the arc-shaped part 2012, reducing the risk of stress concentration, and reducing the probability of expansion and fracture of the outer layer of the pole piece at the position of the arc-shaped part 2012, thereby improving the reliability of the battery monomer 20.

[0160] Embodiment one

[0161] According to the battery monomer 20 provided by the embodiments of the application, the battery monomer 20 comprises an electrode assembly 22 and a buffer member 23.

[0162] The electrode assembly 22 is in a roll core structure, and includes anode sheets, separators 223 and cathode sheets which are stacked and then rolled to form a roll core. The electrode assembly 22 includes a flat portion 2011 and arc-shaped portions 2012 provided at both ends of the flat portion 2011. The buffer 23 is a flat and cuboid-shaped buffer pad, which is made of compressible material and is located at the middle position of the roll layers at the positions of the arc-shaped portions 2012, and is located between the separators 223 and the cathode sheets and fixed on the cathode sheets by adhesion.

[0163] In the above technical solution, at the end of the cycle, the large surface of the electrode assembly 22 is in a top shell, and the positions of the arc-shaped portions 2012 of the electrode assembly 22 continue to expand. The expansion of the electrode sheets will generate a pulling force on the electrode sheets. When the pulling force reaches the limit that the electrode sheets can withstand, the electrode sheets will be pulled apart. The buffer pad allows the electrode sheets to expand, so that the electrode sheets will not be stretched and broken.

[0164] Embodiment Two

[0165] The structure of the battery cell 20 of Embodiment Two is substantially the same as that of the battery cell 20 of Embodiment One, except that two buffer pads are provided in the roll layers at the positions of the arc-shaped portions 2012, and the two buffer pads are respectively provided close to the two ends of the arc-shaped portions 2012.

[0166] The embodiments of the present application also provide a battery device 100, which includes the battery cell 20 of any of the preceding embodiments.

[0167] In the above technical solution, since the buffer 23 in the battery cell 20 can be provided in at least one roll layer, the probability of breakage of the outer electrode sheets can be reduced, and the reliability of the battery cell 20 as a whole can be improved. Thus, the reliability of the battery device 100 including the battery cell 20 can be improved, the use performance of the battery device 100 can be improved, and the service life of the battery device 100 can be prolonged.

[0168] The embodiments of the present application also provide a power consuming device 1000, which includes the battery cell 20 of any of the preceding embodiments, or the battery device 100 of any of the preceding embodiments, and the battery cell 20 or the battery device 100 is used for storing or providing electric energy.

[0169] In the above technical solution, since the battery cell 20 and the battery device 100 have high reliability, the power consuming device 1000 including the battery cell 20 or the battery device 100 also has high reliability, and the power consuming device 1000 can work reliably.

[0170] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0171] The above merely provide preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, all the embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, if not specifically stated. All the technical features and optional technical features of the present application can be combined with each other to form new technical solutions, if not specifically stated. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A battery cell, wherein, The battery cell comprises: a housing assembly; an electrode assembly arranged in the housing assembly and comprising a first tab, a second tab and a separator film arranged between the first tab and the second tab, the electrode assembly comprising a winding axial direction, the electrode assembly being in a jelly-roll structure wound around the winding axial direction and comprising a plurality of winding layers arranged perpendicularly to the winding axial direction, the winding layers comprising the first tab, the separator film and the second tab arranged in a stack; a buffer arranged in at least one of the winding layers and located between the separator film and the first tab or between the separator film and the second tab.

2. The battery cell of claim 1, wherein, The electrode assembly comprises a main body and a tab connected to each other, the main body comprising a flat portion and an arc-shaped portion connected to each other, and the buffer is arranged on the arc-shaped portion.

3. The battery cell of claim 2, wherein, The buffer is bonded to the first tab or the second tab.

4. The battery cell of claim 2 or 3, wherein, An end surface of the buffer facing the separator film is provided with a bonding piece, and in the winding direction of the arc-shaped portion, both ends of the bonding piece protrude from the buffer and are bonded to the first tab or the second tab.

5. The battery cell of claim 2 or 3, wherein, In the winding direction of the arc-shaped portion, the buffer is centrally arranged on the arc-shaped portion.

6. The battery cell of claim 5, wherein, In the winding direction of the arc-shaped portion, the size of the winding layer in which the buffer is arranged in the arc-shaped portion is L1, and the size of the buffer is L2, wherein 0 7. The battery cell of claim 2 or 3, wherein, A plurality of buffers are arranged on the arc-shaped portion, and the plurality of buffers are arranged in a symmetrical manner in the winding direction of the arc-shaped portion.

8. The battery cell of claim 7, wherein, In the winding direction of the arc-shaped portion, the buffer has a center surface, and two buffers are arranged on the arc-shaped portion, and the center surface of the buffer and the quarter division line of the arc length of the arc-shaped portion are close to or coincide with each other.

9. The battery cell of any one of claims 2-8, wherein, Opposite ends of the flat portion are provided with the arc-shaped portion, and the arc-shaped portion is provided with the buffer.

10. The battery cell of claim 9, wherein, The buffers of the two arc-shaped portions are arranged in the same winding layer or different winding layers.

11. The battery cell of any one of claims 1 to 10, wherein, The buffer is provided with a through hole.

12. The battery cell of claim 11, wherein, The through hole is arranged in an array on the buffer.

13. The battery cell of claim 11, wherein, The through hole is a plurality of long holes, and the plurality of through holes are arranged on the buffer in the winding axial direction or a direction perpendicular to the winding axial direction.

14. The battery cell of any one of claims 1-13, wherein, In the winding axial direction, the size of the buffer is greater than or equal to the size of the electrode assembly.

15. The battery cell of any one of claims 1-14, wherein, The thickness of the buffer is T, wherein 0mm 16. The battery cell of claim 15, wherein, 0mm 17. The battery cell of any one of claims 2-10, wherein, In the winding direction of the arc-shaped portion, the size of the buffer is L2, wherein 0mm 18. The battery cell of claim 17, wherein, 2mm 19. The battery cell of any one of claims 1-18, wherein, In the winding axial direction of the electrode assembly, the size of the buffer is L3, wherein 0mm 20. The battery cell of claim 19, wherein, 50mm 21. The battery cell of any one of claims 2-10, wherein, In the arc-shaped portion, the second tab is a cathode tab, and the buffer is arranged between the second tab and the separator film.

22. A battery device, wherein, The battery cell comprises the battery cell as claimed in any one of claims 1 to 21.

23. An electrical device, comprising: A battery cell as defined in any one of claims 1 to 21, or a battery device as defined in claim 22, for storing or providing electrical energy.

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