Battery monomer, battery and electric device

Abstract

The utility model provides a battery monomer, a battery and a power utilization device, and belongs to the technical field of batteries. The single battery comprises a shell, a battery cell and a buffer part, a containing cavity is defined in the shell, the battery cell is arranged in the containing cavity and comprises at least one electrode assembly, the buffer part is arranged in the containing cavity, and on the cross section of the electrode assembly, at least part of the buffer part is located between the shell and the battery cell and surrounds the whole circumference of the battery cell; the buffering piece is an elastic piece with holes, and the holes are communicated with the containing cavity. According to the technical scheme, the buffer piece is arranged between the battery cell and the shell in the whole circle, and the hole communicated with the accommodating cavity is formed in the buffer piece, so that the stress uniformity of the whole circle of the electrode assembly can be improved, and the risk that the outer circle pole piece forms a stress boundary point and is fractured is further reduced; the problems of lithium precipitation or short internal life caused by pole piece breakage are solved, and the reliability and cycle life of the battery monomer are improved.

Description

Technical Field

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

[0002] In recent years, new energy vehicles have developed by leaps and bounds. In the field of electric vehicles, power batteries, as the power source of electric vehicles, play an irreplaceable and important role. Among them, power batteries include several battery cells, however, the reliability of battery cells needs to be improved. Utility Model Content

[0003] The embodiments of the present application provide a battery cell, a battery, and an electrical device, which can improve the reliability of the battery cell.

[0004] In a first aspect, an embodiment of the present application provides a battery cell, comprising: a shell, a battery cell and a buffer, wherein a housing cavity is defined in the shell, the battery cell is disposed in the housing cavity, and comprises at least one electrode assembly, the buffer component is disposed in the housing cavity, and in a cross section of the electrode assembly, at least a portion of the buffer component is located between the shell and the battery cell and surrounds the entire circumference of the battery cell, the buffer component is an elastic component containing pores, and the pores are connected to the housing cavity.

[0005] In the above technical solution, when the electrode assembly expands, since a full circle of buffers is provided between the outer circumference of the battery cell and the shell, the battery cell and the shell can be blocked, so that the battery cell and the shell do not interact directly, and the expanded battery cell can squeeze the buffers at the positions of the whole circumference. Since there are pores in the buffer that are connected to the accommodating cavity, the squeezed buffers can be compressed and provide elastic reaction force to the electrode assembly. Since the buffer can surround the battery cell, the force uniformity of the whole circumference of the electrode assembly can be improved, and the problem of local formation of stress boundary points in the electrode assembly can be improved, thereby reducing the risk of the outer ring pole piece breaking at the stress boundary point, and improving the problems of lithium deposition or internal short caused by the pole piece breaking, which is conducive to improving the reliability and cycle life of the battery cell. Moreover, since the pores in the buffer are connected to the accommodating cavity, the pores can be used to store electrolyte. Compared with the solid or closed buffer, the amount of electrolyte injected into the shell can be increased, and the cycle life of the battery cell can be improved. Furthermore, since the buffer component has pores connected to the accommodating cavity, when the buffer component is squeezed by the expanded electrode assembly, the pores in the buffer component can be squeezed to discharge the electrolyte or gas, so that the buffer component is compressed rather than elongated along the axial direction of the electrode assembly. Therefore, the problem of short-circuiting the positive and negative electrode sheets due to the elongation of the axial end of the buffer component squeezing the axial side isolation membrane of the electrode assembly will not occur, thereby further improving the reliability of the battery cell.

[0006] In some embodiments, both side surfaces of the buffer along the axial direction of the electrode assembly are axial end surfaces, and the pores include first through holes penetrating both side axial end surfaces of the buffer.

[0007] In the above technical solution, the first through hole is easy to process, and the aperture, number and position of the first through hole can be adjusted to adjust the injection amount of the electrolyte and the supporting force provided by the buffer to the electrode assembly, which is beneficial to improving the reliability of the battery cell.

[0008] In some embodiments, the electrode assembly includes a main body and corner portions located at two ends of the main body, and the first through holes are multiple and arranged around the corner portions.

[0009] In the above technical solution, since the plurality of first through holes are arranged around the corner portion, a relatively large space can be provided for arranging the first through holes, which is beneficial to increase the total volume of the first through holes and the injection amount of the electrolyte. In addition, when the wall thickness of the first portion is small, the first through holes are not processed in the first portion, which can reduce the processing difficulty.

[0010] In some embodiments, the pore further includes a second through hole, the second through hole penetrates the outer circumference and / or the inner circumference of the buffer and is connected to the first through hole.

[0011] In the above technical solution, since the second through hole penetrates at least one of the outer circumferential surface and the inner circumferential surface of the buffer, the processing of the second through hole is facilitated, which is conducive to fully utilizing the space in the buffer and further increasing the injection amount of the electrolyte. The second through hole is connected to the first through hole, so that when the buffer is squeezed by the expanded electrode assembly, the first through hole and the second through hole can be promoted to discharge the electrolyte or gas in the hole as soon as possible, balance the pressure on the electrode assembly as soon as possible, and more effectively improve the fracture problem of the electrode assembly.

[0012] In some embodiments, along the axial direction of the electrode assembly, the height of the buffer is greater than the height of the pole piece in the electrode assembly, and the two axial ends of the buffer respectively extend beyond the two axial ends of the pole piece; or, one axial end of the buffer is flush with the corresponding axial end of the pole piece, and the other axial end of the buffer extends beyond the corresponding axial end of the pole piece.

[0013] In the above technical solution, the buffer can surround and protect the pole piece over the entire axial height of the electrode assembly, avoiding the risk of local fracture caused by the formation of stress boundary points due to the lack of support from the buffer, thereby helping to further improve the reliability of the battery cell.

[0014] In some embodiments, the axial ends of the pole piece are respectively the first end and the second end; wherein, both the first end and the second end have protruding pole ears, and the height of the buffer component on the setting side of the first end and the setting side of the second end exceeding the pole piece by a first height, and the first height is 0 to 5 mm; or, all the pole ears in the electrode assembly protrude from the first end, the height of the buffer component on the setting side of the first end exceeding the pole piece by a first height, and the first height is 0 to 5 mm, and the height of the buffer component on the setting side of the second end exceeding the pole piece by a second height, and the second height is 0 to 2 mm.

[0015] In the above technical solution, on the one hand, the buffer can more effectively surround and protect the pole piece, and on the other hand, the part of the buffer that exceeds the height of the pole piece can occupy less space in the shell.

[0016] In some embodiments, the first height is 0-2 mm, and the second height is 0-0.5 mm.

[0017] In the above technical solution, under the premise that the buffer can more effectively surround and protect the pole piece, the space occupied by the part of the buffer that exceeds the height of the pole piece in the shell can be further reduced.

[0018] In some embodiments, the difference between the height of the buffer and the height of the electrode assembly is -2 to 2 mm.

[0019] In the above technical solution, the height of the buffer is close to the hard height of the electrode assembly. On the one hand, the height of the buffer is sufficient to fully protect the electrode from the entire axial height. On the other hand, it can also avoid the problem that the buffer exceeds the hard height too much, resulting in excessive space occupation and affecting the energy density of the battery cell.

[0020] In some embodiments, the difference between the height of the buffer and the height of the electrode assembly is -0.5 to 0.5 mm.

[0021] In the above technical solution, on the one hand, the height of the buffer can be sufficient to fully protect the pole piece from the entire axial height, and on the other hand, it can also avoid the problem that the buffer exceeds the hard height too much, resulting in excessive space occupation and affecting the energy density of the battery cell.

[0022] In some embodiments, the buffer component includes a buffer sleeve in the shape of an integrally molded ring sleeve.

[0023] In the above technical solution, there is no seam around the buffer sleeve, so as to avoid the buffer sleeve breaking at the seam, causing uneven force on the electrode assembly at the corresponding break point, generating stress boundary points, and causing the outer ring electrode to break, thereby improving the reliability of the battery cell.

[0024] In some embodiments, the battery cell includes a plurality of electrode assemblies, and a buffer sleeve is separately disposed outside each electrode assembly.

[0025] In the above technical solution, by separately sleeved a buffer sleeve outside each electrode assembly, each electrode assembly can be supported by the buffer sleeve all around, thereby improving the force balance effect of each electrode assembly, effectively protecting each electrode assembly, and reducing the mutual extrusion between two adjacent electrode assemblies.

[0026] In some embodiments, the battery cell includes a plurality of electrode assemblies, and at least two electrode assemblies are collectively sheathed in the same buffer sheath.

[0027] In the above technical solution, the number of buffer sleeves and assembly processes can be reduced, thereby improving production efficiency.

[0028] In some embodiments, all electrode assemblies are housed together in a same buffer sleeve.

[0029] In the above technical solution, the number of buffer sleeves and assembly processes can be further reduced, thereby improving production efficiency.

[0030] In some embodiments, multiple electrode assemblies encased in the same buffer jacket are in direct contact with each other.

[0031] In the above technical solution, the space occupied by the buffer pad can be reduced, which is beneficial to increase the injection amount of the electrolyte, or to increase the number of turns of the electrode assembly and improve the volume energy density of the battery cell.

[0032] In some embodiments, the buffer component further includes a buffer pad, which is sleeved in the same buffer sleeve and provided between two adjacent electrode assemblies.

[0033] In the above technical solution, each electrode assembly can be supported by the buffer member around its entire circumference, thereby reducing the mutual compression between two adjacent electrode assemblies, thereby improving the protection of each electrode assembly.

[0034] In some embodiments, the cushioning sleeve is integrally formed with the cushioning pad.

[0035] In the above technical solution, since the buffer sleeve and the buffer pad are integrally formed, processing is convenient, and slits at the connection between the buffer sleeve and the buffer pad can be avoided, which would cause uneven force on the electrode assembly at the corresponding slits, generate stress boundary points, and cause the outer ring electrode to break, thereby improving the reliability of the battery cell.

[0036] In some embodiments, the electrode assembly includes a main body and corner portions located at both ends of the main body, the buffer sleeve includes a first portion located between the main body and the shell, and the wall thickness of the buffer pad is less than or equal to the wall thickness of the first portion.

[0037] In the above technical scheme, while reducing the mutual extrusion between two adjacent electrode assemblies and improving the uniformity of force on each electrode assembly throughout the entire circumference, it can also reduce the space occupied by the buffer pad, which is beneficial to increase the injection amount of electrolyte, or increase the number of turns of the electrode assembly and improve the volume energy density of the battery cell.

[0038] In some embodiments, a portion of the surface of the buffer that faces the housing matches the shape of the inner surface of the housing.

[0039] In the above technical solution, the buffer can fully obtain the support of the shell to improve the reliability of the buffer's support for the battery cell, so that the buffer can more reliably and effectively balance the force of the electrode assembly and reduce the risk of fracture at the stress boundary point of the electrode assembly.

[0040] In some embodiments, a portion of the surface of the buffer member facing the electrode assembly matches the shape of an outer surface of the electrode assembly.

[0041] In the above technical solution, the buffer components can fully support the entire circumference of the battery cell, so as to improve the uniformity of the force applied to the entire circumference of the battery cell and reduce the risk of fracture at the stress boundary points formed at the outer ring pole pieces in the battery cell.

[0042] In some embodiments, the electrode assembly includes a main body and corner portions located at both ends of the main body, the buffer includes a first portion located between the main body and the shell, and a second portion located between the corner portion and the shell, and the thickness of the second portion is greater than the thickness of the first portion.

[0043] In the above technical solution, the thickness of the second part is set to be greater than the thickness of the first part, which can better match the free space between the shell and the battery cell, so that after the battery cell is assembled, the first part and the second part are basically not compressed, so as to provide a relatively uniform supporting force to the electrode assembly during the subsequent charging and discharging process of the electrode assembly. Moreover, it will not occur that the shell needs to be enlarged or the electrode assembly needs to be reduced because the thickness of the first part is greater than the thickness of the second part, so that the battery cell can maintain a higher volume energy density while maintaining its current small volume.

[0044] In some embodiments, the compression rate of the second portion is less than or equal to the compression rate of the first portion.

[0045] In the above technical solution, when the compression rates of the first part and the second part are the same, the materials of the two parts can be completely consistent, so as to facilitate processing. When the compression rate of the second part is less than that of the first part, it means that under the same external force, the volume reduction of the second part is less than that of the first part. Since the main body is closer to the shell, it can obtain shell support in a timely manner, while the corner part is far away from the shell and cannot obtain shell support in time, so by setting the compression rate of the second part between the corner part and the shell to be relatively low, the hardness of the second part can be relatively large, and a relatively sufficient support force can be provided to the corner part in time, so that the force of the electrode assembly as a whole is relatively uniform, so that the cracking problem of the pole piece can be more effectively improved.

[0046] In some embodiments, the density of the second part is 40-130 kg / m 3 The density of the first part is 30~110kg / m 3 .

[0047] In the above technical solution, within the above value range, the density of the second part can be greater than the density of the first part, so that it is easy to achieve that the compression rate of the second part is less than the compression rate of the first part, and thus the cracking problem of the pole piece can be more effectively improved.

[0048] In some embodiments, the density of the second part is 70-110 kg / m 3 The density of the first part is 40~60kg / m 3 .

[0049] In the above technical solution, it can be easier to select within the above value range to achieve a density of the second part greater than the density of the first part, thereby easily achieving a compression rate of the second part less than the compression rate of the first part, and thus the cracking problem of the pole piece can be more effectively improved.

[0050] In a second aspect, an embodiment of the present application further provides a battery, comprising a battery cell of any of the above-mentioned solutions.

[0051] In the above technical scheme, since a buffer is provided throughout the entire circle between the battery cell and the shell in the battery cell used in the battery, and the buffer has pores connected to the accommodating cavity, the force uniformity of the entire circumference of the electrode assembly can be improved, thereby reducing the risk of stress boundary points forming and breaking in the outer circle pole pieces, improving problems such as lithium deposition or internal short circuit caused by pole piece fracture, which is beneficial to improving the reliability and cycle life of the battery cell, thereby helping to improve the reliability and life of the battery.

[0052] In a third aspect, an embodiment of the present application further provides an electrical device comprising a battery cell according to any of the above-mentioned solutions.

[0053] In the above technical solution, since the reliability of the battery cell according to the embodiment of the present application is improved, it is helpful to improve the reliability of the electrical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0055] Figure 1 A schematic diagram of the structure of a vehicle provided in some embodiments of the present application;

[0056] Figure 2 An exploded view of the structure of a battery provided in some embodiments of the present application;

[0057] Figure 3 A schematic diagram of a battery cell provided for some embodiments of the present application;

[0058] Figure 4 An exploded view of a battery cell provided for some embodiments of the present application;

[0059] Figure 5 A cross-sectional view of a battery cell provided for some embodiments of the present application;

[0060] Figure 6 A cross-sectional view of a battery cell provided for some embodiments of the present application;

[0061] Figure 7 A cross-sectional view of a battery cell provided in accordance with an embodiment of the present application;

[0062] Figure 8 A cross-sectional view of a battery cell provided for some embodiments of the present application;

[0063] Fig. 9 A partial enlarged view of a battery cell provided in some embodiments of the present application;

[0064] Fig.10 A partial enlarged view of a battery cell provided in some embodiments of the present application;

[0065] Fig.11 A cross-sectional view of a battery cell provided for some embodiments of the present application;

[0066] Fig.12 A cross-sectional view of a battery cell provided for some embodiments of the present application;

[0067] Fig.13A cross-sectional view of a battery cell provided for some embodiments of the present application.

[0068] Figure markings: vehicle 1000; battery 100; controller 200; motor 300; box body 101; first box body 1011; second box body 1012; battery cell 102; shell 1; shell body 11; cover plate 12; accommodating cavity 13; first shell wall 14; second shell wall 15; battery cell 2; electrode assembly 21; pole ear 21a; pole piece 21b; main body 211; corner portion 212; junction position 213; buffer 3; pore 31; first through hole 311; second through hole 312; first part 32; second part 33; buffer sleeve 3a; buffer pad 3b; first direction F1; second direction F2; third direction F3. DETAILED DESCRIPTION

[0069] The following is a further detailed description of the implementation methods of the present application in conjunction with the accompanying drawings and examples. The detailed descriptions and drawings of the following examples are used to illustrate the principles of the present application, but cannot be used to limit the scope of the present application, that is, the present application is not limited to the described embodiments. In the description of the present application, it should be noted that, unless otherwise specified, the meaning of "multiple" is more than two; the orientation or position relationship indicated by the terms "upper", "lower", "left", "right", "inside", "outside", etc. is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. "Vertical" is not vertical in the strict sense, but within the error tolerance range. "Parallel" is not parallel in the strict sense, but within the error tolerance range.

[0070] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0071] In the present application, battery cells may include but are not limited to lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries or magnesium-ion batteries. Battery cells may be in the form of but are not limited to cylinders, flat bodies or rectangular parallelepipeds. Battery cells are generally divided into three types according to the packaging method: cylindrical battery cells, square battery cells and soft-pack battery cells.

[0072] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in the present application may include a battery module or a battery pack. The battery generally includes a box for encapsulating one or more battery cells. The box can prevent liquid or other foreign matter from affecting the charging or discharging of the battery cells.

[0073] A battery cell includes an electrode assembly and an electrolyte. The electrode assembly is composed of a positive electrode sheet, a negative electrode sheet and a separator. A battery cell mainly works by the movement of metal ions between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive current collector. The current collector not coated with the positive active material layer protrudes from the current collector coated with the positive active material layer. The current collector not coated with the positive active material layer serves as a positive electrode ear. Taking a lithium-ion battery as an example, the material of the positive current collector can be aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide, etc.

[0074] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer is coated on the surface of the negative electrode current collector. The current collector not coated with the negative electrode active material layer protrudes from the current collector coated with the negative electrode active material layer. The current collector not coated with the negative electrode active material layer serves as the negative electrode tab. The material of the negative electrode current collector may be copper, and the negative electrode active material may be carbon or silicon, etc. In order to ensure that a large current passes without melting to a certain extent, the number of positive electrode tabs is multiple and stacked together, and the number of negative electrode tabs is multiple and stacked together. The material of the isolation film may be PP or PE, etc.

[0075] In recent years, new energy vehicles have developed by leaps and bounds. In the field of electric vehicles, power batteries, as the power source of electric vehicles, play an irreplaceable and important role. Among them, power batteries include several battery cells. However, during the repeated charging and discharging process of battery cells, the pole pieces will continue to expand and contract. As the life of the battery increases, the expansion of the pole pieces increases, and the accumulated stress of the outer ring pole pieces increases, which is easy to form fractures at the stress boundary points, leading to problems such as lithium deposition or internal shorts, affecting the reliability of the battery cells.

[0076] In order to improve the above-mentioned technical problems, the present application proposes a battery cell, in which a buffer is arranged between the shell and the electrode assembly. The buffer can balance the expansion force generated by the expansion of the battery during the charging and discharging process, improve the fracture of the outer ring electrode sheet, and thus improve the problems such as lithium deposition or internal short caused by the fracture of the electrode sheet, thereby improving the reliability and cycle life of the battery cell.

[0077] In order to more clearly understand the embodiments of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0078] The technical solutions described in the embodiments of the present application are applicable to various electrical devices that use batteries, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, electric tools, electric vehicles, ships and spacecraft, for example, spacecraft include airplanes, rockets, space shuttles and spacecraft, etc.

[0079] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device in an embodiment of the present application.

[0080] Please refer to Figure 1 , Figure 1 A schematic diagram of the structure of a vehicle 1000 provided for some embodiments of the present application. The vehicle 1000 may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 may be provided at the bottom, head or tail of the vehicle 1000. The battery 100 may be used to power the vehicle 1000, for example, the battery 100 may be used as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300, and the controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0081] In some embodiments of the present application, the battery 100 can not only serve as an operating power source for the vehicle 1000, but also serve as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0082] Please refer to Figure 2 , Figure 2An exploded view of the structure of a battery 100 provided for some embodiments of the present application. The battery 100 includes a case 101 and a plurality of battery cells 102, and the battery cells 102 are accommodated in the case 101. Among them, the case 101 is used to provide an assembly space for the battery cells 102, and the case 101 can adopt a variety of structures. In some embodiments, the case 101 may include a first case body 1011 and a second case body 1012, and the first case body 1011 and the second case body 1012 cover each other, and the first case body 1011 and the second case body 1012 jointly define an assembly space for accommodating the battery cells 102. The second box body 1012 may be a hollow structure with one end open, the first box body 1011 may be a plate-like structure, and the first box body 1011 covers the open side of the second box body 1012, so that the first box body 1011 and the second box body 1012 jointly define an assembly space; the first box body 1011 and the second box body 1012 may also be hollow structures with one side open, and the open side of the first box body 1011 covers the open side of the second box body 1012. Of course, the box body 101 formed by the first box body 1011 and the second box body 1012 may be in various shapes, such as a cylinder, a cuboid, etc.

[0083] In the battery 100, multiple battery cells 102 can be connected in series, in parallel, or in a hybrid connection. A hybrid connection means that multiple battery cells 102 are connected in series and in parallel. Multiple battery cells 102 can be directly connected in series, in parallel, or in a hybrid connection, and then the whole formed by multiple battery cells 102 is accommodated in the box 101; of course, the battery 100 can also be a battery module formed by multiple battery cells 102 connected in series, in parallel, or in a hybrid connection, and then multiple battery modules are connected in series, in parallel, or in a hybrid connection to form a whole, and accommodated in the box 101. The battery 100 may also include other structures, for example, the battery 100 may also include a busbar component for realizing electrical connection between multiple battery cells 102.

[0084] Each battery cell 102 may be, but is not limited to, a secondary battery or a primary battery; it may also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery. The battery cell 102 may be, but is not limited to, a cylinder, a flat body, or a rectangular parallelepiped. Figure 3 In the illustrated embodiment, the battery cell 102 is in the form of a rectangular parallelepiped.

[0085] Reference Figure 3 and Figure 4Some embodiments of the present application provide a battery cell 102, which may include a housing 1 and a battery cell 2. The housing 1 defines a receiving cavity 13, the battery cell 2 is disposed in the receiving cavity 13, and the battery cell 2 includes at least one electrode assembly 21. That is, the battery cell 2 may include one electrode assembly 21 or multiple electrode assemblies 21, and the number of electrode assemblies 21 may be selected according to the capacity requirements of the battery cell 102.

[0086] For example, in combination Figure 4 The shell 1 may include a shell body 11 and a cover plate 12. One end of the shell body 11 has an opening. The electrode assembly 21 is inserted into the shell body 11 through the opening, and the cover plate 12 covers the opening. However, the present application is not limited thereto. The shell 1 may also be in other forms, for example, it may include two half shells that are joined together, or the shell 1 may also include a sleeve with two open ends, and two end caps provided at both ends of the sleeve. Exemplarily, the material of the shell 1 may include, but is not limited to, plastic, copper, iron, aluminum, stainless steel, and aluminum alloy.

[0087] In addition, the shell 1 can be in various shapes, such as a cylinder, a cuboid, etc. The shape of the shell 1 can be determined according to the specific shape of the electrode assembly 21. For example, if the electrode assembly 21 is a cylindrical structure, the shell 1 can be selected as a cylindrical structure; if the electrode assembly 21 is a cuboid structure, the shell 1 can be selected as a cuboid structure. Figure 4 In the illustrated embodiment, the battery cell 2 includes two electrode assemblies 21 , the electrode assemblies 21 are rectangular parallelepiped structures, and the two electrode assemblies 21 are stacked along the thickness direction of the electrode assemblies 21 , and the housing 1 is a hollow rectangular parallelepiped structure.

[0088] In the embodiment of the present application, the electrode assembly 21 is a winding structure, also known as a winding core, which is formed by or mainly by stacking and winding the electrode sheet 21b and the isolation film, wherein the electrode sheet includes a positive electrode sheet and a negative electrode sheet, and the isolation film is arranged between the positive electrode sheet and the negative electrode sheet to insulate the positive electrode sheet from the negative electrode sheet. It can be understood that since the electrode assembly 21 is a winding structure, the electrode assembly 21 has an axial direction (such as Figure 4 The first direction F1 shown in FIG. 1 is a first direction F2, and the electrode assembly 21 is cut in a plane perpendicular to the axial direction of the electrode assembly 21 to obtain a cross section of the electrode assembly 21 (e.g. Figure 5 In general, along the axial direction of the electrode assembly 21, the height of the separator is greater than the height of the electrode piece, so that the separator can fully and completely isolate the positive electrode piece from the negative electrode piece, improve the insulation reliability of the positive electrode piece and the negative electrode piece, and improve the short circuit problem.

[0089] Generally, after the electrode assembly 21 is wound, it is further subjected to hot pressing and shaping to obtain a flat, substantially rectangular electrode assembly 21. Therefore, the electrode assembly 21 may include a flattened main body 211 and corner portions 212 located at both ends of the main body 211 and naturally bent into an arc form, for example Figure 4 As shown, before and after hot pressing, the axial direction of the electrode assembly 21 is the first direction F1. After hot pressing, the thickness direction of the electrode assembly 21 is the second direction F2, and the width direction of the electrode assembly 21 is the third direction F3. The first direction F1, the second direction F2 and the third direction F3 are perpendicular to each other. The thickness direction of the main body 211 is the second direction F2, and the corners 212 are located at both ends of the main body 211 in the third direction F3. In this way, by hot pressing the electrode assembly 21, on the one hand, it is convenient to install the electrode assembly 21 into the housing 1, and on the other hand, the gap between the pole piece and the isolation film can be reduced by hot pressing, so that under the premise of the same volume of the accommodating cavity 13, the number of turns of the electrode assembly 21 can be increased, which is conducive to improving the energy density of the battery cell 102.

[0090] In the embodiments of the present application, refer to Figure 5 and Figure 6 The battery cell 102 further includes a buffer member 3 disposed in the accommodation cavity 13. In the cross section of the electrode assembly 21, at least part of the buffer member 3 is located between the shell 1 and the battery cell 2 and surrounds the entire circumference of the battery cell 2. That is, in the cross section perpendicular to the axial direction of the electrode assembly 21, the buffer member 3 is entirely or partially located between the battery cell 2 and the shell 1 and surrounds the entire circumference of the contour of the battery cell 2. In other words, the buffer member 3 is entirely or partially located around the entire circumference of the contour of the battery cell 2, so that the portion of the buffer member 3 is located between the battery cell 2 and the shell 1. The buffer member 3 is an elastic member containing pores 31, and the pores 31 are connected to the accommodation cavity 13, wherein the pores 31 may be pores 31 inherent in the material itself, or may be pores 31 obtained by machining.

[0091] For example, combined with Figure 5 When the battery cell 2 includes only one electrode assembly 21, the buffer member 3 surrounds the electrode assembly 21, so that the buffer member 3 surrounds the entire circumference of the battery cell 2. Figure 6 When the battery cell 2 includes a plurality of electrode assemblies 21, the buffer member 3 surrounds all of the electrode assemblies 21, so that the buffer member 3 surrounds the entire circumference of the battery cell 2. Figure 7When the battery cell 2 includes multiple electrode assemblies 21, the buffer 3 includes multiple buffer sleeves 3a, and the number of buffer sleeves 3a is less than or equal to the number of electrode assemblies 21, wherein when the number of buffer sleeves 3a is the same as the number of electrode assemblies 21, each electrode assembly 21 is respectively surrounded by a corresponding buffer sleeve 3a, so that the buffer 3 surrounds the entire battery cell 2; and when the number of buffer sleeves 3a is less than the number of electrode assemblies 21, each electrode assembly 2 is surrounded by a buffer sleeve 3a, and at least two electrode assemblies 2 are surrounded by the same buffer sleeve 3a, that is, at least one buffer sleeve 3a surrounds more than one electrode assembly 2, so that the buffer 3 can also surround the entire battery cell 2.

[0092] For example, in combination Figure 8 The battery cell 2 includes an electrode assembly 21, and the electrode assembly 21 is a winding core of a rectangular parallelepiped structure and includes a main body 211 and corner portions 212 located at both ends of the main body 211. The shell 1 is a hollow rectangular parallelepiped structure. The shell 1 has two side walls (such as Figure 8 The gap between the first shell wall 14 shown in FIG. 1 and the main body 211 is small, and the shell walls (such as the first shell wall 14 shown in FIG. 14 ) at both ends of the shell 1 oppositely arranged in the width direction of the electrode assembly 21, that is, in the third direction F3 Figure 8 The gap between the second shell wall 15) and the corner portion 212 is larger.

[0093] When the electrode assembly 21 expands, the main body 211 and the corner portion 212 are both subjected to pressure from the buffer member 3. The forces at various positions of the electrode assembly 21 are relatively balanced, and it is not easy to form a stress boundary point at the junction 213 between the main body 211 and the corner portion 212. This can reduce the risk of the outer ring electrode sheet breaking at this point, improve problems such as lithium deposition or internal short caused by electrode sheet breakage, and thus improve the reliability and cycle life of the battery cell 102.

[0094] Therefore, according to the battery cell 102 of the embodiment of the present application, when the electrode assembly 21 expands, since a full circle of buffer parts 3 are provided between the outer circumferential surface of the battery cell 2 and the shell 1, direct interaction between the battery cell 2 and the shell 1 can be avoided, and the expanded battery cell 2 can squeeze the buffer parts 3 at the entire circumference. Since the buffer parts 3 have pores 31 connected to the accommodating cavity 13, the squeezed buffer parts 3 can be compressed and provide an elastic reaction force to the electrode assembly 21. Moreover, since the buffer parts 3 surround the battery cell 2 all around, the force uniformity of the electrode assembly 21 all around can be improved, and the problem of local formation of stress boundary points in the electrode assembly 21 can be improved, thereby reducing the risk of fracture of the outer ring pole piece at the stress boundary point, and improving problems such as lithium deposition or internal short caused by pole piece fracture, which is beneficial to improving the reliability and cycle life of the battery cell 102.

[0095] Moreover, since the pores 31 in the buffer 3 are connected to the accommodating cavity 13, the pores 31 can be used to store electrolyte, and compared with a solid or closed buffer, the amount of electrolyte injected into the housing 1 can be increased, thereby improving the cycle life of the battery cell 102. Moreover, since the buffer 3 has pores 31 in communication with the accommodating cavity 13, when the buffer 3 is squeezed by the expanded electrode assembly 21, the pores 31 in the buffer 3 can be squeezed to discharge the electrolyte or gas, so that the buffer 3 is compressed instead of being elongated along the axial direction of the electrode assembly 21 (such as the first direction F1 described above), so that the problem of internal shorting of the positive and negative electrodes due to the elongation of the axial end of the buffer 3 squeezing the axial side separation membrane of the electrode assembly 21 will not occur, thereby further improving the reliability of the battery cell 102.

[0096] For example, if a closed structure such as an airbag is used to replace the buffer 3, since the airbag is a sealed structure, it can completely fill the gap between the shell and the battery cell, reducing the residual space in the shell and the injection amount of the electrolyte is relatively low. Moreover, when the battery cell expands and squeezes the airbag, since the airbag is a closed structure, the airbag will stretch along the axial direction of the electrode assembly when squeezed, squeezing the axial side isolation membrane of the electrode assembly, causing the problem of short inside the positive and negative electrode sheets. The buffer 3 used in this application has a pore 31 connected to the accommodating cavity 13, which can effectively solve the above technical problems.

[0097] In some embodiments of the present application, Fig. 9 , the two side surfaces of the buffer 3 along the axial direction of the electrode assembly 21 are axial end surfaces, and the pore 31 includes a first through hole 311 that penetrates the two side axial end surfaces of the buffer 3. That is, the pore 31 includes the first through hole 311, and the first through hole 311 penetrates the two side end surfaces of the buffer 3 in the axial direction of the electrode assembly 21, that is, in the first direction F1. Therefore, the first through hole 311 is easy to process, and the injection amount of the electrolyte and the supporting force provided by the buffer 3 to the electrode assembly 21 can be adjusted by adjusting the aperture, number and position of the first through hole 311, so as to improve the reliability of the battery cell 102.

[0098] In some embodiments of the present application, there are multiple first through holes 311 and they are arranged around the corner portion 212. Fig. 9The buffer 3 includes a first portion 32 located between the main body 211 and the shell 1, and a second portion 33 between the corner portion 212 and the shell 1. Generally, the distance between the corner portion 212 and the shell 1 is larger than the distance between the main body 211 and the shell 1. Therefore, the thickness of the second portion 33 can be set to be larger than the thickness of the first portion 32 to adapt to the space between the shell 1 and the battery cell 2, so that the second portion 33 can have a relatively large space to set the first through hole 311, which is beneficial to increase the total volume of the first through hole 311 and the injection amount of the electrolyte. In addition, when the wall thickness of the first portion 32 is small, the first through hole 311 is not processed in the first portion 32, which can reduce the processing difficulty.

[0099] In some embodiments of the present application, Fig.10 The pore 31 further includes a second through hole 312, and the second through hole 312 penetrates at least one of the outer circumference and the inner circumference of the buffer 3. It can be understood that in the embodiment of the present application, the side surface of the buffer 3 facing the housing 1 is the outer circumference of the buffer 3, and the side surface of the buffer 3 facing the battery cell 2 is the inner circumference of the buffer 3.

[0100] Thus, since the second through hole 312 passes through at least one of the outer circumferential surface and the inner circumferential surface of the buffer 3, the processing of the second through hole 312 is facilitated, and it is conducive to fully utilizing the space in the buffer 3, and further increasing the injection amount of the electrolyte. The second through hole 312 is connected with the first through hole 311, so that when the buffer 3 is squeezed by the expanded electrode assembly 21, the first through hole 311 and the second through hole 312 can be promoted to discharge the electrolyte or gas in the hole as soon as possible, balance the pressure on the electrode assembly 21 as soon as possible, and more effectively improve the fracture problem of the electrode assembly 21.

[0101] In some embodiments of the present application, Figure 4 and Fig.12 , along the axial direction of the electrode assembly 21 (such as the first direction F1), the height H2 of the buffer 3 is greater than the height H1 of the electrode sheet 21b (including the positive electrode sheet and the negative electrode sheet) in the electrode assembly 21, so that the axial ends of the buffer 3 can correspond to the axial ends beyond the electrode sheet 21b, for example Fig.12As shown in , the upper end of the buffer 3 is higher than the upper end of the pole piece 21b (i.e., the first end 21b1), and the lower end of the buffer 3 is lower than the lower end of the pole piece 21b (i.e., the second end 21b2). Alternatively, one axial end of the buffer 3 is flush with the corresponding axial end of the pole piece 21b, and the other axial end of the buffer 3 exceeds the corresponding axial end of the pole piece 21b. For example, the upper end of the buffer 3 is flush with the upper end of the pole piece 21b (i.e., the first end 21b1), and the lower end of the buffer 3 is lower than the lower end of the pole piece 21b (i.e., the second end 21b2). For another example, the upper end of the buffer 3 is higher than the upper end of the pole piece 21b (i.e., the first end 21b1), and the lower end of the buffer 3 is flush with the lower end of the pole piece 21b (i.e., the second end 21b2).

[0102] In this way, the buffer 3 can surround and protect the pole piece 21b over the entire axial height of the electrode assembly 21, avoiding the risk of local fracture caused by the formation of stress boundary points due to the pole piece 21b being partially unsupported by the buffer 3, thereby helping to further improve the reliability of the battery cell 102.

[0103] For example, in combination Fig.12 The axial ends of the pole piece 21b are respectively a first end 21b1 and a second end 21b2, both of which have protruding pole ears 21a, and the height of the buffer member 3 on the setting side of the first end 21b1 exceeding the pole piece 21b is a first height h1, and the height of the buffer member 3 on the setting side of the second end 21b2 exceeding the pole piece 21b is also a first height h1, and the value range of the first height h1 is 0 to 5 mm.

[0104] That is, the buffer member 3 is higher than the pole piece 21b on the side where the first end 21b1 is arranged (eg Fig.12 The upper h1 shown in FIG. 1 is 0 to 5 mm, for example, 0 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, etc. The buffer 3 exceeds the height of the pole piece 21 b (as shown in FIG. 1 ) on the side where the second end 21 b2 is arranged. Fig.12 The lower h1) shown in is 0-5 mm, for example, 0 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, etc. It can be understood that when 0 mm is taken, it is equivalent to exceeding 0 mm, that is, it is flush with the case.

[0105] It is worth noting that although the height of the buffer 3 on the side of the first end 21b1 exceeding the pole piece 21b and the height of the buffer 3 on the side of the second end 21b2 exceeding the pole piece 21b have the same value range, their specific values ​​may be the same or different.

[0106] Therefore, by limiting the height range of the buffer component 3 exceeding the pole piece 21b on the pole ear side of the electrode assembly 21 to 0 to 5 mm, on the one hand, the buffer component 3 can more effectively surround and protect the pole piece 21b, and on the other hand, the height of the buffer component 3 exceeding the height of the pole piece 21b can occupy a smaller space in the shell 1.

[0107] For example, the first height h1 is 0-2 mm, that is, the buffer member 3 exceeds the height of the pole piece 21b on the side where the first end 21b1 is arranged (eg Fig.12 The upper h1 shown in FIG. 1 is 0 to 2 mm, for example, 0 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, etc. The buffer 3 exceeds the height of the pole piece 21 b (as shown in FIG. 1 ) on the side where the second end 21 b2 is arranged. Fig.12 The lower h1) shown in FIG is 0 to 2 mm, for example, 0 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, etc.

[0108] Therefore, by limiting the height range of the buffer member 3 exceeding the pole piece 21b on the pole ear side of the electrode assembly 21 to 0 to 2 mm, the height space occupied by the portion of the buffer member 3 that exceeds the pole piece 21b in the shell 1 can be further reduced, while the buffer member 3 can more effectively surround and protect the pole piece 21b.

[0109] For example, in combination Fig.13 The two axial ends of the pole piece 21b are respectively the first end 21b1 and the second end 21b2. All the pole ears 21a in the electrode assembly 21 protrude from the first end 21b1. The height of the buffer 3 on the side where the first end 21b1 is set beyond the pole piece 21b is a first height h1, and the first height h1 is 0 to 5 mm, for example, 0 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, etc. The height of the buffer 3 on the side where the second end 21b2 is set beyond the pole piece 21b is a second height h2, and the second height h2 is 0 to 2 mm, for example, 0 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, etc.

[0110] Therefore, by limiting the height range of the buffer component 3 exceeding the pole piece 21b on the pole ear side of the electrode assembly 21 to 0 to 5 mm, and at the same time limiting the height range of the buffer component 3 exceeding the pole piece 21b on the non-pole ear side of the electrode assembly 21 to 0 to 2 mm, on the one hand, the buffer component 3 can more effectively surround and protect the pole piece 21b, and on the other hand, the height of the buffer component 3 exceeding the height of the pole piece 21b can occupy a smaller space in the shell 1.

[0111] For example, the first height h1 is 0-2 mm, and the second height h2 is 0-0.5 mm, that is, the height of the buffer member 3 on the side where the first end 21b1 is disposed beyond the pole piece 21b is (eg Fig.13 The upper h1 shown in FIG. 1 is 0 to 2 mm, for example, 0 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, etc. The buffer 3 exceeds the height of the pole piece 21 b (as shown in FIG. 1 ) on the side where the second end 21 b2 is arranged. Fig.13 The lower h2) shown in FIG is 0 to 0.5 mm, for example, 0 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, etc.

[0112] Therefore, by limiting the height range of the buffer member 3 exceeding the pole piece 21b on the pole ear side of the electrode assembly 21 to 0 to 2 mm, and at the same time limiting the height range of the buffer member 3 exceeding the pole piece 21b on the non-pole ear side of the electrode assembly 21 to 0 to 0.5 mm, the height space occupied by the portion of the buffer member 3 that exceeds the pole piece 21b in the shell 1 can be further reduced, while the buffer member 3 can more effectively surround and protect the pole piece 21b.

[0113] In some embodiments of the present application, such as 12 and Fig.13 As shown, the difference between the height H2 of the buffer 3 and the height H3 of the electrode assembly 21 is -2 to 2 mm. The height H3 of the electrode assembly 21 refers to the hard height of the electrode assembly 21. Usually, the axial height of the separator is greater than the axial height of the pole piece. Therefore, the portion of the separator that exceeds the pole piece will be flattened during processing. After flattening, the height of the electrode assembly 21 is the hard height. In the above embodiment, by limiting the difference between the height H2 of the buffer 3 and the height H3 of the electrode assembly 21 to -2 to 2 mm, that is, the height difference between the two is within ±2 mm, so that the height of the buffer 3 can be close to the hard height of the electrode assembly 21, for example, the height of the buffer 3 is greater than the hard height, but the height difference is 0 to 2 mm, or the height of the buffer 3 is less than the hard height, but the height difference is -2 to 0 mm. For example, the height difference between the height of the buffer 3 and the hard height of the electrode assembly 21 is -2 mm, -1.5 mm, -1 mm, 0 mm, 1 mm, 1.5 mm, 2 mm, etc. Therefore, on the one hand, the height of the buffer 3 can be sufficient to fully protect the pole piece 21b from the entire axial height, and on the other hand, it can also avoid the problem that the buffer 3 exceeds the hard height too much, resulting in excessive space occupation and affecting the energy density of the battery cell 102.

[0114] For example, as 12 and Fig.13As shown, the difference between the height H2 of the buffer 3 and the height H3 of the electrode assembly 21 is -0.5 to 0.5 mm. For example, the height difference between the height of the buffer 3 and the hard height of the electrode assembly 21 is -0.5 mm, -0.4 mm, -0.3 mm, -0.2 mm, -0.1 mm, 0 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, etc. Thus, on the one hand, the height of the buffer 3 can be made sufficient to fully protect the pole piece 21 b from the entire axial height, and on the other hand, it can also avoid the problem that the buffer 3 exceeds the hard height too much, resulting in excessive space occupation and affecting the energy density of the battery cell 102.

[0115] In some embodiments of the present application, Figure 5 As shown, the buffer member 3 includes a buffer sleeve 3a in the shape of an integral ring sleeve. As a result, the buffer sleeve 3a has no seams all around, thereby preventing the buffer sleeve 3a from breaking at the seams, causing the electrode assembly 21 to be subjected to uneven force at the corresponding break, generating stress boundary points, and causing the outer ring electrode to break, thereby improving the reliability of the battery cell 102.

[0116] It is worth noting that when the buffer sleeve 3a is an integrally formed ring sleeve, the assembly order of the buffer sleeve 3a and the battery cell 2 is not limited. For example, during the preparation of the battery cell 102, the battery cell 2 can be placed in the buffer sleeve 3a first, or the buffer sleeve 3a can be placed outside the battery cell 2 first, and then the pre-assembled battery cell 2 and the buffer sleeve 3a can be installed together in the shell 1. Or, for another example, the buffer sleeve 3a can be installed in the shell 1 first, and then the battery cell 2 can be installed in the shell 1, so that the battery cell 2 is installed in the buffer sleeve 3a in the shell 1.

[0117] In some embodiments of the present application, when the buffer sleeve 3a is an integrally formed ring sleeve shape, and the battery core 2 includes a plurality of electrode assemblies 21, in some specific examples, such as Figure 7 As shown, each electrode assembly 21 may be separately provided with a buffer sleeve 3a, or, in some other specific examples, such as Figure 6 As shown, at least two electrode assemblies 21 may be collectively sheathed in the same buffer sleeve 3a.

[0118] For example Figure 7 As shown, when each electrode assembly 21 is separately sleeved with a buffer sleeve 3a, the number of buffer sleeves 3a is the same as the number of electrode assemblies 21, and they are sleeved one by one. In this way, when multiple electrode assemblies 21 are combined together, it can still be satisfied that the buffer member 3 surrounds the entire circumference of the battery cell 2 on the cross section of the electrode assembly 21, and the buffer member 3 not only surrounds the entire circumference of the battery cell 2, but also surrounds the entire circumference of each electrode assembly 21 in the battery cell 2. Fig.10As shown in the figure, the upper, left and right parts of the buffer sleeve 3a disposed on the outer surface of the upper electrode assembly 21 and the lower, left and right parts of the buffer sleeve 3a disposed on the outer surface of the lower electrode assembly 21 surround the entire circumference of the battery cell 2 (i.e., two electrode assemblies 21). Therefore, by separately arranging a buffer sleeve 3a on the outer surface of each electrode assembly 21, each electrode assembly 21 can be supported by the buffer sleeve 3a throughout the circumference, thereby improving the force balancing effect of each electrode assembly 21, effectively protecting each electrode assembly 21, and reducing the mutual compression between two adjacent electrode assemblies 21.

[0119] For example Figure 6 and Fig.11 As shown, when at least two electrode assemblies 21 are collectively sheathed in the same buffer sleeve 3a, the number of buffer sleeves 3a and the assembly process can be reduced, thereby improving production efficiency. When at least two electrode assemblies 21 are collectively sheathed in the same buffer sleeve 3a, the buffer sleeve 3a may be one or more. When there is only one buffer sleeve 3a, all electrode assemblies 21 may be collectively sheathed in the same buffer sleeve 3a (e.g. Figure 6 As shown in FIG. 1 ), the number of buffer sleeves 3a and the assembly process can be further reduced, thereby improving production efficiency. When there are multiple buffer sleeves 3a, the number of electrode assemblies 21 is greater than the number of buffer sleeves 3a. At this time, each buffer sleeve 3a is sleeved with an electrode assembly 21, and at least one buffer sleeve 3a is sleeved with more than one electrode assembly 21 at the same time, thereby achieving flexible setting.

[0120] In some embodiments, for example Fig.11 As shown, when at least two electrode assemblies 21 are collectively sheathed in the same buffer sleeve 3a, a buffer pad 3b may be further arranged between the multiple electrode assemblies 21 in the same buffer sleeve 3a. Thus, by arranging the buffer pad 3b between two adjacent electrode assemblies 21, each electrode assembly 21 may be supported by the buffer member 3 all around, thereby reducing the mutual extrusion between the two adjacent electrode assemblies 21 and improving the protection of each electrode assembly 21.

[0121] For example, in some other embodiments, Figure 6 As shown, when at least two electrode assemblies 21 are collectively sheathed in the same buffer sleeve 3a, the buffer pad 3b disposed between two adjacent electrode assemblies 21 may be eliminated, that is, the multiple electrode assemblies 21 sheathed in the same buffer sleeve 3a are in direct contact with each other, or in other words, the buffer pad 3b is not disposed between the multiple electrode assemblies 21 in the same buffer sleeve 3a. In this case, the space occupied by the buffer pad 3b can be reduced, which is beneficial to increase the amount of electrolyte injected, or to increase the number of turns of the electrode assembly 21, thereby improving the volume energy density of the battery cell 102.

[0122] For example, Fig.11 As shown, the buffer sleeve 3a and the buffer pad 3b are integrally formed, which is convenient for processing and can avoid slitting at the connection between the buffer sleeve 3a and the buffer pad 3b, which causes uneven force on the electrode assembly 21 at the corresponding slits, produces stress boundary points, and causes the outer ring electrode to break, thereby improving the reliability of the battery cell 102.

[0123] For example, in other embodiments of the present application, the buffer component can also be configured to be composed of multiple parts, such as two semi-annular parts bonded together to form a full ring, or four parts bonded end to end in sequence to form a full ring.

[0124] In some embodiments of the present application, the buffer sleeve 3a includes a first portion 32 located between the main body 211 and the housing 1, and the wall thickness t1 of the buffer pad 3b is less than or equal to the wall thickness t2 of the first portion 32. Thus, while reducing the mutual squeezing between two adjacent electrode assemblies 21 and improving the uniformity of force on each electrode assembly 21 throughout the entire circumference, the space occupied by the buffer pad 3b can also be reduced, which is beneficial to increasing the amount of electrolyte injected, or increasing the number of turns of the electrode assembly 21, and improving the volume energy density of the battery cell 102.

[0125] In some embodiments of the present application, Fig.11 As shown, the portion of the surface of the buffer 3 facing the shell 1 matches the shape of the inner surface of the shell 1. As a result, the buffer 3 can fully obtain the support of the shell 1 to improve the reliability of the buffer 3 supporting the battery cell 2 at various locations, so that the buffer 3 can more reliably and effectively balance the force of the electrode assembly 21, and reduce the risk of fracture of the electrode assembly 21 due to the formation of stress boundary points.

[0126] For example, Fig.11 As shown, when the battery cell 2 includes a plurality of electrode assemblies 21, and the plurality of electrode assemblies 21 are collectively sheathed in the same buffer sleeve 3a, the entire outer circumference of the buffer sleeve 3a faces the housing 1 and matches the shape of the inner surface of the housing 1. Figure 7 As shown, when the battery cell 2 includes a plurality of electrode assemblies 21, and each electrode assembly 21 is separately covered with a buffer sleeve 3a, the portion of the outer circumferential surface of each buffer sleeve 3a facing the shell 1 matches the shape of the inner surface of the shell 1 at the corresponding position, for example Figure 7 The upper, left and right parts of the outer circumferential surface of the buffer sleeve 3a arranged outside the upper electrode assembly 21 and the lower, left and right parts of the outer circumferential surface of the buffer sleeve 3a arranged outside the lower electrode assembly 21 are all facing the shell 1 and matching the inner surface shape of the shell 1.

[0127] In some embodiments of the present application, Fig.11As shown, the portion of the surface of the buffer 3 facing the electrode assembly 21 matches the shape of the outer surface of the electrode assembly 21. As a result, the battery cell 2 can be fully supported by the buffer 3 at all locations around the entire circumference, thereby improving the uniformity of the force applied to the battery cell 2 at all locations around the entire circumference and reducing the risk of fracture at the stress boundary point formed by the outer ring electrode of the battery cell 2.

[0128] For example, Fig.11 As shown, when the battery cell 2 includes multiple electrode assemblies 21, and the multiple electrode assemblies 21 are collectively sheathed in the same buffer sleeve 3a, the inner circumference of the buffer sleeve 3a faces the multiple electrode assemblies 21, thereby matching the outer surface shapes of the corresponding positions of the multiple electrode assemblies 21, and at the same time, the surface of the buffer pad 3b also faces the electrode assembly 21, thereby matching the outer surface shapes of the corresponding positions of the electrode assembly 21. For example, Figure 7 As shown, when the battery cell 2 includes multiple electrode assemblies 21 and each electrode assembly 21 is individually sleeved with a buffer sleeve 3a, the inner circumferential surface of each buffer sleeve 3a faces the outer surface of the electrode assembly 21 it surrounds and matches the outer surface shape of the corresponding electrode assembly 21.

[0129] In some embodiments of the present application, Figure 5 As shown, when the electrode assembly 21 includes a main body 211 and corner portions 212 located at both ends of the main body 211, the buffer member 3 includes a first portion 32 located between the main body 211 and the shell 1, and a second portion 33 located between the corner portion 212 and the shell 1, the thickness of the second portion 33 is greater than the thickness of the first portion 32. Typically, the main body 211 is relatively flat and closer to the shell 1, while the corner portion 212 is in an arc shape and farther from the shell 1. The thickness of the second portion 33 is set to be greater than the thickness of the first portion 32, which can better match the free space between the shell 1 and the battery cell 2, so that after the battery cell 102 is assembled, the first portion 32 and the second portion 33 are both basically uncompressed, so as to provide a relatively uniform supporting force to the electrode assembly 21 during the subsequent charging and discharging process of the electrode assembly 21. Moreover, it is not necessary to increase the shell 1 or reduce the electrode assembly 21 because the thickness of the first portion 32 is greater than the thickness of the second portion 33, so that the battery cell 102 can maintain a higher volume energy density while maintaining its current small volume.

[0130] In some embodiments of the present application, the compression rate of the second part 33 is less than or equal to the compression rate of the first part 32. When the compression rates of the first part 32 and the second part 33 are the same, the materials of the two parts can be completely consistent, so as to facilitate processing. When the compression rate of the second part 33 is less than the compression rate of the first part 32, it means that under the same external force, the volume reduction degree of the second part 33 is less than the volume reduction degree of the first part 32. Since the main body 211 is closer to the shell 1, it can obtain the support of the shell 1 in a timely manner, while the corner part 212 is far away from the shell 1 and cannot obtain the support of the shell 1 in time, so by setting the compression rate of the second part 33 between the corner part 212 and the shell 1 to be relatively low, the hardness of the second part 33 can be relatively large, and a relatively sufficient support force can be provided to the corner part 212 in time, so that the force of the electrode assembly 21 as a whole is relatively uniform, so that the cracking problem of the pole piece can be more effectively improved.

[0131] It is understandable that "the compression rate of a material" refers to the degree to which the volume of a material is reduced under the action of an external force. The compression rate is an important indicator to measure the deformation capacity of a material after being subjected to a force, and is also one of the important parameters of the mechanical properties of the material. The compression rate of a material is related to the properties of the material, and the compression rates of different materials are also different. For example, when the materials are the same, the greater the porosity, the higher the compression rate, and the smaller the porosity, the lower the compression rate. Therefore, the compression rate of the first part 32 and the second part 33 can be adjusted by adjusting the material or parameters such as porosity.

[0132] It is understood that the method for measuring the material compressibility is well known to those skilled in the art. For example, a 1 mm thick sample can be cut into 50*100 mm 2 , place it horizontally in the center of the press plate, adjust the pressure to 10000N, start the press, and when the pressure probe displays data, record the thickness d1. When the pressure stabilizes, record the thickness d2. The compression rate of the sample at 2Mpa = (d1-d2) / d1.

[0133] In some embodiments of the present application, the compression rate of the buffer 3 is 0-80%. For example, the compression rate of the buffer 3 can be 0, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, etc. Through testing, it is found that the compression rate of the buffer 3 has an impact on the breakage and wrinkling of the pole piece. The compression rate of the buffer 3 is high, it is easy to compress, the expansion space of the electrode assembly 21 is large, the pole piece is easy to break, but not easy to wrinkle; while the compression rate of the buffer 3 is low, it is not easy to compress, the expansion space of the electrode assembly 21 is small, the pole piece is easy to wrinkle, but relatively not easy to break.

[0134] Therefore, the appropriate compression rate can be tested experimentally to reduce the risk of pole piece fracture and improve the problem of pole piece wrinkling. For example, the compression rate of buffer 3 can be selected as 40%, and the Crack SOH is 62.5%, which is a relatively small value. The pole piece is not easy to crack, and the pole piece is only slightly wrinkled, so that the risk of pole piece fracture and the problem of pole piece wrinkling can be better taken into account. For another example, when the compression rate of buffer 3 is 90%, although there is basically no wrinkling problem, the Crack SOH is 78.2%, which is a relatively large value, and the pole piece is easy to break.

[0135] For example, the density of the second portion 33 is 40 to 130 kg / m 3 The density of the first part 32 is 30-110 kg / m 3 Therefore, within the above range, the density of the second part 33 can be greater than the density of the first part 32, so that the compression rate of the second part 33 can be less than the compression rate of the first part 32, thereby effectively improving the cracking problem of the pole piece. For example, the density of the second part 33 is 40kg / m 3 、60kg / m 3 、80kg / m 3 , 100kg / m 3 , 120kg / m 3 , 130kg / m 3 etc., the density of the first part 32 is 30 kg / m 3 , 40kg / m 3 , 50kg / m 3 、60kg / m 3 , 70kg / m 3 、80kg / m 3 , 90kg / m 3 , 100kg / m 3 , 110kg / m 3 wait.

[0136] For example, the density of the second portion 33 is 70 to 110 kg / m 3 The density of the first part 32 is 40-60 kg / m 3 Therefore, it is easier to select in the above value range to achieve that the density of the second part 33 is greater than the density of the first part 32, so that it is easy to achieve that the compression rate of the second part 33 is less than the compression rate of the first part 32, and then the cracking problem of the pole piece can be effectively improved. For example, the density of the second part 33 is 70kg / m 3 、80kg / m 3 , 90kg / m 3 , 100kg / m 3 , 110kg / m3 etc., the density of the first part 32 is 40 kg / m 3 , 50kg / m 3 、60kg / m 3 wait.

[0137] Exemplarily, a material can be selected that has a smaller adsorption force on the electrolyte than the isolation film in the core, such as but not limited to PE (polyethylene), PP (polypropylene), PET (polyethylene terephthalate), PC (polycarbonate), PPS (polyphenylene sulfide), glass fiber, carbon fiber, and one or more composite materials.

[0138] According to some embodiments of the present application, the present application further provides a battery 100, comprising a battery cell 102 of any of the above solutions. Since the reliability of the battery cell 102 according to the embodiments of the present application is improved, it is helpful to improve the reliability of the battery 100. It is worth noting that the battery 100 according to the embodiments of the present application may include a box body 101 or may not include the box body 101.

[0139] Exemplarily, the battery 100 further includes a busbar component, and there are multiple battery cells 102, and at least two of them are electrically connected through the busbar component. Thus, multiple battery cells 102 can be connected in series and / or in parallel. For example, when multiple battery cells 102 are connected in series, the anode of one battery cell 102 is connected to the cathode of the next battery cell 102 through a busbar component, and the cathode of the battery cell 102 is connected to the anode of the previous battery cell 102 through another busbar component.

[0140] The embodiment of the present application also provides an electric device, including a battery cell 102 of any of the above solutions. The battery 100 is used to provide electric energy to the electric device. The electric device can be any of the above-mentioned devices or systems using the battery cell 102. Since the reliability of the battery cell 102 is improved, it is beneficial to improve the working power performance of the electric device.

[0141] Below, refer to Figure 6 , describing a battery cell 102 according to a specific embodiment of the present application.

[0142] The battery cell 102 includes: a shell 1, a battery cell 2 and a buffer 3. The shell 1 defines a receiving cavity 13. The battery cell 2 is disposed in the receiving cavity 13 and includes two electrode assemblies 21. The buffer 3 is disposed in the receiving cavity 13. The buffer 3 is in the shape of an integrally formed ring sleeve. On the cross section of the electrode assembly 21, the buffer 3 surrounds the battery cell 2 all around, so that the buffer 3 can be located between the shell 1 and the battery cell 2. The outer peripheral surface of the buffer 3 matches the inner surface shape of the shell 1, and the inner peripheral surface of the buffer 3 matches the outer surface shape of the corresponding positions of the two electrode assemblies 21. The electrode assembly 21 includes a main body 211 and corner portions 212 located at both ends of the main body 211. The buffer 3 includes a first portion 32 located between the main body 211 and the shell 1, and a second portion 33 located between the corner portion 212 and the shell 1. The thickness of the second portion 33 is greater than the thickness of the first portion 32. The buffer 3 is an elastic member including a pore 31 and the pore 31 is connected to the accommodating cavity 13. The two side surfaces of the buffer 3 along the axial direction of the electrode assembly 21 are axial end surfaces. The pore 31 includes a first through hole 311 penetrating the two side axial end surfaces of the buffer 3. The first through holes 311 are multiple and are arranged around the corner portion 212. Along the axial direction of the electrode assembly 21, the height of the buffer 3 is greater than the height of the pole piece in the electrode assembly 21, and the height of the buffer 3 is close to the hard height of the electrode assembly 21.

[0143] In the above technical scheme, when the electrode assembly 21 expands, since a full circle of buffer parts 3 are provided between the outer circumference of the battery cell 2 and the shell 1, direct interaction between the battery cell 2 and the shell 1 can be avoided, and the expanded battery cell 2 can squeeze the buffer parts 3 at the entire circumference. Since the buffer parts 3 have pores 31 connected to the accommodating cavity 13, the squeezed buffer parts 3 can be compressed and provide elastic reaction force to the electrode assembly 21. Moreover, since the buffer parts 3 surround the battery cell 2 all around, the force uniformity of the electrode assembly 21 all around can be improved, and the problem of local formation of stress boundary points in the electrode assembly 21 can be improved, thereby reducing the risk of fracture of the outer ring pole piece at the stress boundary point, and improving the problems of lithium deposition or internal short caused by the fracture of the pole piece, which is beneficial to improving the reliability and cycle life of the battery cell 102.

[0144] Moreover, since the pores 31 in the buffer 3 are connected to the accommodating cavity 13, the pores 31 can be used to store electrolyte, and compared with a solid or closed buffer, the amount of electrolyte injected into the housing 1 can be increased, thereby improving the cycle life of the battery cell 102. Moreover, since the buffer 3 has pores 31 in communication with the accommodating cavity 13, when the buffer 3 is squeezed by the expanded electrode assembly 21, the pores 31 in the buffer 3 can be squeezed to discharge the electrolyte or gas, so that the buffer 3 is compressed instead of being elongated along the axial direction of the electrode assembly 21 (such as the first direction F1 described above), so that the problem of internal shorting of the positive and negative electrodes due to the elongation of the axial end of the buffer 3 squeezing the axial side separation membrane of the electrode assembly 21 will not occur, thereby further improving the reliability of the battery cell 102.

[0145] In addition, since the buffer 3 is in the shape of an integrally formed ring sleeve, there is no seam around the buffer 3, so that the buffer 3 can be prevented from breaking at the seam, resulting in uneven force on the electrode assembly 21 at the corresponding break, generating a stress boundary point, and causing the outer ring electrode to break, thereby improving the reliability of the battery cell 102. It is worth noting that the assembly order of the buffer 3 and the battery cell 2 is not limited. For example, during the preparation of the battery cell 102, the battery cell 2 can be placed in the buffer 3 first, or the buffer 3 can be placed outside the battery cell 2 first, and then the pre-assembled battery cell 2 and the buffer 3 can be loaded into the shell 1 together. Or, for another example, the buffer 3 can be loaded into the shell 1 first, and then the battery cell 2 can be loaded into the shell 1, so that the battery cell 2 is loaded into the buffer 3 in the shell 1. Exemplarily, the material of the buffer 3 may include but is not limited to one of PE (polyethylene), PP (polypropylene), PET (polyethylene terephthalate), PC (polycarbonate), PPS (polyphenylene sulfide), glass fiber, carbon fiber, and multiple composite materials.

[0146] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0147] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. 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, characterized in that: include: A housing, wherein a receiving cavity is defined in the housing; A battery cell, the battery cell is disposed in the accommodating cavity and includes at least one electrode assembly; A buffer member is disposed in the accommodating cavity. On the cross section of the electrode assembly, at least a portion of the buffer member is located between the shell and the battery cell and surrounds the entire circumference of the battery cell. The buffer member is an elastic member containing pores, and the pores are connected to the accommodating cavity.

2. The battery cell according to claim 1, characterized in that: The two side surfaces of the buffer member along the axial direction of the electrode assembly are axial end surfaces, and the pores include first through holes penetrating the two side axial end surfaces of the buffer member.

3. The battery cell according to claim 2, characterized in that: The electrode assembly includes a main body and corner portions located at two ends of the main body, and a plurality of first through holes are arranged around the corner portions.

4. The battery cell according to claim 2, characterized in that: The pore further includes a second through hole, which passes through the outer circumferential surface and / or the inner circumferential surface of the buffer and is connected to the first through hole.

5. The battery cell according to any one of claims 1 to 4, characterized in that: Along the axial direction of the electrode assembly, the height of the buffer member is greater than the height of the pole piece in the electrode assembly; The two axial ends of the buffer component respectively extend beyond the two axial ends of the pole piece; or, one axial end of the buffer component is flush with the corresponding axial end of the pole piece, and the other axial end of the buffer component extends beyond the corresponding axial end of the pole piece.

6. The battery cell according to claim 5, characterized in that: The two axial ends of the pole piece are respectively a first end and a second end; Wherein, both the first end and the second end have protruding pole ears, and the height of the buffer member on the setting side of the first end and the setting side of the second end exceeding the pole piece is a first height, and the first height is 0-5 mm; Alternatively, all the pole ears in the electrode assembly protrude from the first end, the height of the buffer component on the side where the first end is set exceeds the pole piece by a first height, and the first height is 0 to 5 mm, and the height of the buffer component on the side where the second end is set exceeds the pole piece by a second height, and the second height is 0 to 2 mm.

7. The battery cell according to claim 6, characterized in that: The first height is 0-2 mm, and the second height is 0-0.5 mm.

8. The battery cell according to claim 5, characterized in that: The difference between the height of the buffer and the height of the electrode assembly is -2 to 2 mm.

9. The battery cell according to claim 8, characterized in that: The difference between the height of the buffer and the height of the electrode assembly is -0.5 to 0.5 mm.

10. The battery cell according to claim 1, characterized in that: The buffer component comprises a buffer sleeve in the shape of an integrally formed ring sleeve.

11. The battery cell according to claim 10, characterized in that: The battery core comprises a plurality of electrode assemblies, and each of the electrode assemblies is separately sheathed with a buffer sheath.

12. The battery cell according to claim 10, characterized in that: The battery core comprises a plurality of electrode assemblies, and at least two of the electrode assemblies are sheathed together in the same buffer sleeve.

13. The battery cell according to claim 12, characterized in that: All the electrode assemblies are collectively sheathed in the same buffer sheath.

14. The battery cell according to claim 12 or 13, characterized in that: A plurality of electrode assemblies housed in the same buffer sleeve are in direct contact with each other.

15. The battery cell according to claim 12 or 13, characterized in that: The buffer component also includes a buffer pad, which is sleeved in the same buffer sleeve and is arranged between two adjacent electrode assemblies.

16. The battery cell according to claim 15, characterized in that: The buffer sleeve and the buffer pad are integrally formed.

17. The battery cell according to claim 15, characterized in that: The electrode assembly includes a main body and corner parts located at both ends of the main body, the buffer sleeve includes a first part located between the main body and the shell, and the wall thickness of the buffer pad is less than or equal to the wall thickness of the first part.

18. The battery cell according to claim 1, characterized in that: A portion of the surface of the buffer member facing the housing matches the shape of an inner surface of the housing.

19. The battery cell according to claim 1, characterized in that: A portion of the surface of the buffer member facing the electrode assembly matches the shape of an outer surface of the electrode assembly.

20. The battery cell according to claim 1, characterized in that The electrode assembly includes a main body and corner portions located at both ends of the main body, the buffer member includes a first portion located between the main body and the shell, and a second portion located between the corner portion and the shell, and the thickness of the second portion is greater than the thickness of the first portion.

21. The battery cell according to claim 20, characterized in that: The compression rate of the second part is less than or equal to the compression rate of the first part.

22. The battery cell according to claim 21, characterized in that: The density of the second part is 40-130 kg / m 3 The density of the first part is 30-110 kg / m 3 .

23. The battery cell according to claim 22, characterized in that: The density of the second part is 70-110 kg / m 3 The density of the first part is 40-60 kg / m 3 .

24. A battery, characterized in that: Comprising a battery cell according to any one of claims 1-23.

25. An electrical device, characterized in that: Comprising a battery cell according to any one of claims 1-23.

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