Battery cell, battery, and electric device

Abstract

A battery cell, a battery, and an electric device, relating to the technical field of batteries. The battery cell comprises a housing, a cell core, and a buffer member; an accommodating cavity is defined in the housing; the cell core is arranged in the accommodating cavity, and comprises at least one electrode assembly; the buffer member is arranged in the accommodating cavity; on the cross section of the electrode assembly, at least part of the buffer member is located between the housing and the cell core and surrounds the entire perimeter of the cell core; the buffer member is an elastic member containing pores; and the pores are communicated with the accommodating cavity.

Description

Battery cells, batteries and electrical devices

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on the Chinese patent application with application number 202420561788.2 and application date 2024-03-21, and claims the priority of the above-mentioned Chinese patent application. The entire content of the above-mentioned Chinese patent application is hereby introduced into this application as a reference. Technical Field

[0003] 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

[0004] In recent years, new energy vehicles have experienced rapid development. In the electric vehicle sector, power batteries, as the power source of electric vehicles, play an irreplaceable and important role. Power batteries consist of several battery cells, but the reliability of these cells needs to be improved.

[0005] Summary of the Invention

[0006] 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.

[0007] 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 accommodating cavity is defined in the shell, the battery cell is disposed in the accommodating cavity, and comprises at least one electrode assembly, the buffer being disposed in the accommodating cavity, and in a cross section of the electrode assembly, at least a portion of the buffer being located between the shell and the battery cell and surrounding the entire circumference of the battery cell, the buffer being an elastic member containing pores, and the pores being connected to the accommodating cavity.

[0008] In the above technical solution, when the electrode assembly expands, a full circle of buffers is provided between the outer circumference of the battery cell and the shell, which can block the battery cell and the shell from direct interaction. The expanded battery cell can squeeze the buffers at all positions around the entire circumference. Since the buffers have pores connected to the accommodating cavity, the squeezed buffers can be compressed and provide an elastic reaction force to the electrode assembly. Moreover, since the buffers can surround the entire circumference of the battery cell, the force uniformity of the entire circumference of the electrode assembly can be improved, and the problem of local stress boundary points in the electrode assembly can be improved, thereby reducing the risk of fracture of the outer ring electrode at the stress boundary points, and improving problems such as lithium deposition or internal short circuit caused by electrode fracture, thereby helping to improve 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 use of solid or closed buffers, the amount of electrolyte injected into the shell can be increased, thereby improving the cycle life of the battery cell. Moreover, since the buffer has pores connected to the accommodating cavity, when the buffer is squeezed by the expanded electrode assembly, the pores in the buffer can be squeezed to discharge the electrolyte or gas, so that the buffer is compressed rather than stretched along the axial direction of the electrode assembly. Therefore, the axial end of the buffer is stretched, and the axial side isolation membrane of the electrode assembly is squeezed, causing the problem of shorting the positive and negative electrodes, thereby further improving the reliability of the battery cell.

[0009] In some embodiments, both 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 both side axial end surfaces of the buffer member.

[0010] 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, thereby improving the reliability of the battery cell.

[0011] In some embodiments, the electrode assembly includes a main body and corner portions located at both ends of the main body, and the first through holes are multiple and arranged around the corner portions.

[0012] In the above technical solution, since the multiple first through holes are arranged around the corner portion, a relatively large space is provided for the first through holes, thereby facilitating an increase in the total volume of the first through holes and an increase in the amount of electrolyte injected. Furthermore, when the wall thickness of the first portion is relatively small, the first through holes can be omitted from the first portion, thereby reducing the processing difficulty.

[0013] In some embodiments, the pore further includes a second through hole, the second through hole passes through the outer circumference and / or inner circumference of the buffer component and is connected to the first through hole.

[0014] In the above technical solution, since the second through-hole penetrates at least one of the outer and inner circumferential surfaces of the buffer component, machining of the second through-hole is facilitated, thereby fully utilizing the space within the buffer component and further increasing the amount of electrolyte injected. The second through-hole is connected to the first through-hole. Therefore, when the buffer component is squeezed by the expanding electrode assembly, the first and second through-holes can be used to quickly expel the electrolyte or gas within the holes, balancing the pressure on the electrode assembly and more effectively alleviating the problem of electrode assembly fracture.

[0015] 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.

[0016] 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 piece in the pole piece, thereby helping to further improve the reliability of the battery cell.

[0017] In some embodiments, the axial ends of the electrode piece are respectively the first end and the second end; wherein, the first end and the second end both have protruding electrode 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 electrode piece is a first height, and the first height is 0 to 5 mm; or, all the electrode ears in the electrode assembly protrude from the first end, the height of the buffer member on the setting side of the first end exceeding the electrode piece is a first height, and the first height is 0 to 5 mm, and the height of the buffer member on the setting side of the second end exceeding the electrode piece is a second height, and the second height is 0 to 2 mm.

[0018] 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 portion of the buffer that exceeds the height of the pole piece can occupy less space in the housing.

[0019] In some embodiments, the first height is 0-2 mm, and the second height is 0-0.5 mm.

[0020] In the above technical solution, under the premise that the buffer component can more effectively surround and protect the pole piece, the space occupied by the portion of the buffer component that exceeds the height of the pole piece in the housing can be further reduced.

[0021] In some embodiments, the difference between the height of the buffer and the height of the electrode assembly is -2 to 2 mm.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] In some embodiments, the buffer component includes a buffer sleeve in the shape of an integrally molded ring.

[0026] In the above technical solution, there is no seam around the buffer sleeve, which can avoid the buffer sleeve from 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.

[0027] In some embodiments, the battery cell includes a plurality of electrode assemblies, and a buffer sleeve is separately provided outside each electrode assembly.

[0028] In the above technical solution, by separately arranging 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.

[0029] In some embodiments, the battery cell includes multiple electrode assemblies, and at least two electrode assemblies are housed in the same buffer sleeve.

[0030] In the above technical solution, the number of buffer sleeves and assembly processes can be reduced, thereby improving production efficiency.

[0031] In some embodiments, all electrode assemblies are housed together in a same buffer sleeve.

[0032] In the above technical solution, the number of buffer sleeves and assembly processes can be further reduced, thereby improving production efficiency.

[0033] In some embodiments, multiple electrode assemblies housed in the same buffer sleeve are in direct contact with each other.

[0034] In the above technical solution, the space occupied by the buffer pad can be reduced, which is beneficial to increasing the injection amount of the electrolyte, or is beneficial to increasing the number of turns of the electrode assembly and improving the volume energy density of the battery cell.

[0035] In some embodiments, the buffer component further includes a buffer pad, which is housed in the same buffer sleeve and provided between two adjacent electrode assemblies.

[0036] In the above technical solution, each electrode assembly can be supported by the buffer member throughout its entire circumference, reducing the mutual compression between two adjacent electrode assemblies, thereby improving the protection of each electrode assembly.

[0037] In some embodiments, the cushioning cover is integrally formed with the cushioning pad.

[0038] In the above technical solution, since the buffer sleeve and the buffer pad are integrally formed, processing is facilitated, 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.

[0039] 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.

[0040] In the above technical solution, 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 increasing the injection amount of electrolyte, or increasing the number of turns of the electrode assembly and improving the volume energy density of the battery cell.

[0041] In some embodiments, a portion of the surface of the buffer facing the housing matches the shape of the inner surface of the housing.

[0042] 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 caused by the formation of stress boundary points in the electrode assembly.

[0043] 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.

[0044] 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 caused by the stress boundary points formed in the outer ring of the battery cell.

[0045] In some embodiments, 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.

[0046] 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 of the electrode assembly. Moreover, it will not happen 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 smaller volume.

[0047] In some embodiments, the compression rate of the second portion is less than or equal to the compression rate of the first portion.

[0048] In the above technical solution, when the compression rates of the first and second parts are the same, the materials of the two parts can be completely consistent, thereby facilitating processing. When the compression rate of the second part is lower than that of the first part, it means that under the same external force, the volume of the second part is reduced less than that of the first part. Since the main body is closer to the shell, it can obtain support from the shell more promptly, while the corner part is farther away from the shell and cannot obtain support from the shell in a timely manner. Therefore, 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 high, providing more sufficient support force to the corner part in a timely manner, making the force applied to the entire electrode assembly relatively uniform and consistent, thereby more effectively improving the cracking problem of the electrode piece.

[0049] 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 .

[0050] 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, thereby easily achieving a compression rate of the second part lower than the compression rate of the first part, thereby more effectively improving the cracking problem of the pole piece.

[0051] 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 .

[0052] In the above technical solution, it is 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 can more effectively improve the cracking problem of the pole piece.

[0053] In a second aspect, an embodiment of the present application further provides a battery comprising a battery cell according to any of the above solutions.

[0054] In the above technical solution, since buffer parts are provided throughout the entire circle between the battery cells and the shell in the battery cells used in the battery, and the buffer parts have pores connected to the accommodating cavity, the force uniformity of the entire circle of the electrode assembly can be improved, thereby reducing the risk of stress boundary points forming and breaking in the outer ring pole pieces, improving problems such as lithium plating or internal short circuit caused by pole piece fracture, which is beneficial to improving the reliability and cycle life of the battery cells, thereby improving the reliability and life of the battery.

[0055] 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 solutions.

[0056] In the above technical solution, since the reliability of the battery cell according to the embodiment of the present application is improved, it is beneficial to improve the reliability of the electrical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. 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 relevant drawings can be obtained based on these drawings without creative work.

[0058] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0059] FIG2 is an exploded view of the structure of a battery provided in some embodiments of the present application;

[0060] FIG3 is a schematic diagram of a battery cell provided in some embodiments of the present application;

[0061] FIG4 is an exploded view of a battery cell provided in some embodiments of the present application;

[0062] FIG5 is a cross-sectional view of a battery cell provided in some embodiments of the present application;

[0063] FIG6 is a cross-sectional view of a battery cell provided in some embodiments of the present application;

[0064] FIG7 is a cross-sectional view of a battery cell provided by one embodiment of the present application;

[0065] FIG8 is a cross-sectional view of a battery cell provided in some embodiments of the present application;

[0066] FIG9 is a partial enlarged view of a battery cell provided in some embodiments of the present application;

[0067] FIG10 is a partial enlarged view of a battery cell provided in some embodiments of the present application;

[0068] FIG11 is a cross-sectional view of a battery cell provided in some embodiments of the present application;

[0069] FIG12 is a cross-sectional view of a battery cell provided in some embodiments of the present application;

[0070] FIG13 is a cross-sectional view of a battery cell provided in some embodiments of the present application.

[0071] Figure markings: vehicle 1000; battery 100; controller 200; motor 300; case 101; first case body 1011; second case body 1012; battery cell 102; shell 1; shell body 11; cover 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; aperture 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

[0072] The following is a further detailed description of the embodiments 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 are not 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 positional 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, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore 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 perpendicular in the strict sense, but is within the allowable error range. "Parallel" is not parallel in the strict sense, but is within the allowable error range.

[0073] It should also be noted that, in the description of this application, unless otherwise specified or limited, the terms "installed," "connected," and "connected" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0074] In this 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, but are not limited to, cylindrical, flat, or rectangular. Battery cells are generally categorized into three types based on packaging: cylindrical, prismatic, and pouch-type.

[0075] The battery referred to in the embodiments of this application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in this application may include a battery module or a battery pack. A battery generally includes a casing that encloses one or more battery cells. The casing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0076] 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. The battery cell primarily relies on the movement of metal ions between the positive and negative electrode sheets to operate. 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 the positive electrode tab. Taking lithium-ion batteries 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.

[0077] The negative electrode sheet includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative current collector. The current collector uncoated with the negative active material layer protrudes from the current collector coated with the negative active material layer. The current collector uncoated with the negative active material layer serves as the negative electrode tab. The negative current collector can be made of copper, and the negative active material can be carbon or silicon, for example. To ensure that high currents can pass without melting, multiple positive electrode tabs are stacked together, and multiple negative electrode tabs are stacked together. The separator can be made of materials such as PP or PE.

[0078] In recent years, new energy vehicles have experienced rapid development. In the electric vehicle sector, power batteries, as the power source of electric vehicles, play an irreplaceable and important role. Power batteries consist of several cells. However, during repeated charge and discharge, the electrodes of these cells expand and contract. As the battery cell's lifespan increases, the amount of electrode expansion increases, increasing the accumulated stress on the outer electrode ring. This can easily lead to fractures at stress boundaries, causing problems such as lithium deposition and internal short circuits, compromising the reliability of the battery cells.

[0079] In order to improve the above 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, and thus improve the problems such as lithium deposition or internal short caused by the fracture of the electrode, thereby improving the reliability and cycle life of the battery cell.

[0080] 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.

[0081] The technical solutions described in the embodiments of the present application are applicable to various battery-powered electrical devices, such as mobile phones, portable devices, laptop computers, electric vehicles, electric toys, electric tools, electric vehicles, ships and spacecraft, etc. For example, spacecraft include airplanes, rockets, space shuttles and spacecraft, etc.

[0082] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device according to an embodiment of the present application.

[0083] Please refer to Figure 1, which is a schematic structural diagram of a vehicle 1000 provided in some embodiments of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can serve as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. 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.

[0084] In some embodiments of the present application, the battery 100 can serve not only as an operating power source for the vehicle 1000, but also 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.

[0085] Please refer to Figure 2, which is an exploded view of the structure of the battery 100 provided in some embodiments of the present application. The battery 100 includes a box body 101 and a plurality of battery cells 102, and the battery cells 102 are accommodated in the box body 101. The box body 101 is used to provide an assembly space for the battery cells 102, and the box body 101 can adopt a variety of structures. In some embodiments, the box body 101 may include a first box body 1011 and a second box body 1012, and the first box body 1011 and the second box body 1012 cover each other, and the first box body 1011 and the second box body 1012 jointly define an assembly space for accommodating the battery cells 102. The second box body 1012 can be a hollow structure with one end open, and the first box body 1011 can be a plate-like structure. 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 can 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 can be of various shapes, such as a cylinder, a cuboid, etc.

[0086] In the battery 100, multiple battery cells 102 can be connected in series, in parallel, or in a hybrid configuration. A hybrid configuration refers to multiple battery cells 102 being connected both in series and in parallel. Multiple battery cells 102 can be directly connected in series, in parallel, or in a hybrid configuration, and then the entire structure formed by the multiple battery cells 102 is housed within the housing 101. Alternatively, the battery 100 can be constructed by first connecting multiple battery cells 102 in series, in parallel, or in a hybrid configuration to form a battery module. The multiple battery modules are then connected in series, in parallel, or in a hybrid configuration to form a single structure, which is then housed within the housing 101. The battery 100 may also include other structures, such as a busbar assembly for electrically connecting the multiple battery cells 102.

[0087] 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, cylindrical, flat, or rectangular. For example, referring to the embodiment shown in FIG3 , the battery cell 102 is a rectangular parallelepiped.

[0088] 3 and 4 , some embodiments of the present application provide a battery cell 102. The battery cell 102 may include a housing 1 and a battery cell 2. The housing 1 defines a receiving cavity 13. The battery cell 2 is disposed within the receiving cavity 13 and includes at least one electrode assembly 21. Specifically, the battery cell 2 may include one electrode assembly 21 or multiple electrode assemblies 21. The number of electrode assemblies 21 may be selected based on the capacity requirements of the battery cell 102.

[0089] By way of example, with reference to FIG4 , the housing 1 may include a body 11 and a cover plate 12 . The body 11 has an opening at one end, the electrode assembly 21 is inserted into the body 11 through the opening, and the cover plate 12 covers the opening. However, the present application is not limited thereto, and the housing 1 may also be in other forms, for example, including two half shells joined together, or the housing 1 may also include a sleeve with both ends open and two end caps provided at both ends of the sleeve. By way of example, the material of the housing 1 may include, but is not limited to, plastic, copper, iron, aluminum, stainless steel, or aluminum alloy.

[0090] In addition, the shell 1 can be of 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 has a cylindrical structure, the shell 1 can be selected as a cylindrical structure; if the electrode assembly 21 has a cuboid structure, the shell 1 can be selected as a cuboid structure. For example, in the embodiment shown in Figure 4, the battery cell 2 includes two electrode assemblies 21, the electrode assemblies 21 have a cuboid structure, and the two electrode assemblies 21 are stacked along the thickness direction of the electrode assembly 21, and the shell 1 has a hollow cuboid structure.

[0091] In an embodiment of the present application, the electrode assembly 21 is a wound structure, also known as a winding core, which is formed by or mainly by stacking and winding the electrode sheets 21b and the isolation membrane, wherein the electrode sheets include positive electrode sheets and negative electrode sheets, and the isolation membrane is provided between the positive electrode sheets and the negative electrode sheets to insulate the positive electrode sheets from the negative electrode sheets. It is understandable that since the electrode assembly 21 is a wound structure, the electrode assembly 21 has an axial direction (the first direction F1 as shown in FIG4 ), and the electrode assembly 21 is cut with a plane perpendicular to the axial direction of the electrode assembly 21 to obtain a cross-section of the electrode assembly 21 (such as the cross-section shown in FIG5 ). Typically, along the axial direction of the electrode assembly 21, the height of the isolation membrane is greater than the height of the electrode sheets, so that the isolation membrane can fully and comprehensively isolate the positive electrode sheets from the negative electrode sheets, thereby improving the insulation reliability of the positive electrode sheets and the negative electrode sheets and improving the short circuit problem.

[0092] Typically, after the electrode assembly 21 is wound, it is subjected to hot pressing to obtain a flat, roughly 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, as shown in Figure 4, 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 corner portions 212 are located at both ends of the main body 211 in the third direction F3. In this way, by hot pressing and shaping the electrode assembly 21, on the one hand, it is convenient for the electrode assembly 21 to be installed in the shell 1, and on the other hand, the gap between the electrode sheet and the isolation membrane 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 beneficial to improving the energy density of the battery cell 102.

[0093] In the embodiment of the present application, referring to Figures 5 and 6 , the battery cell 102 further includes a buffer member 3 disposed within the accommodating cavity 13. In a cross-section of the electrode assembly 21, at least a portion of the buffer member 3 is located between the housing 1 and the battery cell 2 and surrounds the entire circumference of the battery cell 2. That is, in a 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 housing 1 and surrounds the entire circumference of the battery cell 2. Alternatively, the buffer member 3 entirely or partially surrounds the entire circumference of the battery cell 2, such that this portion of the buffer member 3 is located between the battery cell 2 and the housing 1. The buffer member 3 is an elastic member containing pores 31, and the pores 31 are in communication with the accommodating cavity 13. The pores 31 may be inherent in the material or machined.

[0094] For example, with reference to FIG5 , 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. For another example, with reference to FIG6 , when the battery cell 2 includes multiple 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. For another example, with reference to FIG7 , when the battery cell 2 includes multiple electrode assemblies 21, the buffer member 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. When the number of buffer sleeves 3a is the same as the number of electrode assemblies 21, each electrode assembly 21 is surrounded by a corresponding buffer sleeve 3a, so that the buffer member 3 surrounds the entire circumference of the battery cell 2. 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, i.e., at least one buffer sleeve 3a surrounds more than one electrode assembly 2, thereby also achieving the buffer member 3 surrounding the entire circumference of the battery cell 2.

[0095] Exemplarily, in conjunction with Figure 8, the battery cell 2 includes an electrode assembly 21, and the electrode assembly 21 is a winding core with a rectangular 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 structure. The gap between the two side shell walls (such as the first shell wall 14 shown in Figure 8) of the shell 1 relatively arranged in the thickness direction of the electrode assembly 21, that is, the second direction F2 and the main body 211 is small, and the gap between the two end shell walls (such as the second shell wall 15 shown in Figure 8) of the shell 1 relatively arranged in the width direction of the electrode assembly 21, that is, the third direction F3 and the corner portions 212 is large.

[0096] When the electrode assembly 21 expands, the main body 211 and the corner part 212 are both subjected to pressure from the buffer part 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 part 212. This can reduce the risk of the outer ring electrode piece breaking at this location, improve problems such as lithium deposition or internal short circuit caused by the electrode piece breaking, and thus improve the reliability and cycle life of the battery cell 102.

[0097] 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 peripheral 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 positions throughout 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 throughout the circumference, the force uniformity of the electrode assembly 21 throughout the circumference 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 electrode piece at the stress boundary point, and improving problems such as lithium deposition or internal short circuit caused by electrode piece fracture, thereby helping to improve the reliability and cycle life of the battery cell 102.

[0098] Furthermore, because the pores 31 within the buffer member 3 communicate with the accommodating cavity 13, the pores 31 can be utilized to store electrolyte. This increases the amount of electrolyte injected into the housing 1 compared to a solid or sealed buffer member, thereby improving the cycle life of the battery cell 102. Furthermore, because the buffer member 3 includes pores 31 communicating with the accommodating cavity 13, when the buffer member 3 is squeezed by the expanding electrode assembly 21, the pores 31 within the buffer member 3 are squeezed to expel electrolyte or gas, resulting in compression of the buffer member 3 rather than extension along the axial direction of the electrode assembly 21 (e.g., the first direction F1 described above). Consequently, the axial extension of the buffer member 3 prevents compression of the axial separator of the electrode assembly 21, thereby preventing internal shorts between the positive and negative electrodes. This further improves the reliability of the battery cell 102.

[0099] For example, if a closed structure such as an airbag were used in place of the buffer 3, the airbag's sealed structure would more completely fill the gap between the housing and the cell, reducing the residual space within the housing and requiring a relatively low electrolyte injection volume. Furthermore, when the cell expands and squeezes the airbag, the closed structure would cause the airbag to extend axially along the electrode assembly, squeezing the axial separator of the electrode assembly and causing internal shorts between the positive and negative electrode sheets. The buffer 3 employed in this application, however, has a pore 31 communicating with the accommodating cavity 13, effectively resolving the aforementioned technical issues.

[0100] In some embodiments of the present application, as shown in FIG9 , the two side surfaces of the buffer member 3 along the axial direction of the electrode assembly 21 serve as axial end surfaces, and the aperture 31 includes first through-holes 311 that penetrate the two side axial end surfaces of the buffer member 3. Specifically, the aperture 31 includes first through-holes 311 that penetrate the two side end surfaces of the buffer member 3 along the axial direction of the electrode assembly 21, i.e., in the first direction F1. As a result, the first through-holes 311 are easy to process, and the diameter, number, and position of the first through-holes 311 can be adjusted to adjust the amount of electrolyte injected and the support provided by the buffer member 3 to the electrode assembly 21, thereby improving the reliability of the battery cell 102.

[0101] In some embodiments of the present application, there are multiple first through holes 311 and they are arranged around the corner portion 212. In conjunction with Figure 9, the buffer member 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 accommodate the space between the shell 1 and the battery cell 2. In this way, 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, not processing the first through hole 311 in the first portion 32 can reduce the processing difficulty.

[0102] In some embodiments of the present application, with reference to FIG10 , the aperture 31 further includes a second through hole 312, which penetrates at least one of the outer circumferential surface and the inner circumferential surface of the buffer 3. It will be understood that in the embodiments of the present application, the surface of the buffer 3 facing the housing 1 is the outer circumferential surface of the buffer 3, and the surface of the buffer 3 facing the battery cell 2 is the inner circumferential surface of the buffer 3.

[0103] Thus, because the second through-hole 312 penetrates at least one of the outer and inner circumferential surfaces of the buffer member 3, machining of the second through-hole 312 is facilitated, and the space within the buffer member 3 is fully utilized, further increasing the amount of electrolyte injected. The second through-hole 312 communicates with the first through-hole 311. Therefore, when the buffer member 3 is squeezed by the expanding electrode assembly 21, the first and second through-holes 311, 312 can be used to quickly expel the electrolyte or gas within the holes, thereby quickly balancing the pressure on the electrode assembly 21 and more effectively alleviating the problem of fracture of the electrode assembly 21.

[0104] In some embodiments of the present application, in combination with Figures 4 and 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 piece 21b (including the positive electrode piece and the negative electrode piece) in the electrode assembly 21, so that the axial ends of the buffer 3 can respectively correspond to the axial ends of the electrode piece 21b. For example, as shown in Figure 12, the upper end of the buffer 3 is higher than the upper end of the electrode piece 21b (i.e., the first end 21b1), and the lower end of the buffer 3 is lower than the lower end of the electrode 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 extends beyond 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).

[0105] In this way, the buffer member 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 member 3, thereby helping to further improve the reliability of the battery cell 102.

[0106] For example, in combination with Figure 12, the axial ends of the pole piece 21b are respectively the first end 21b1 and the second end 21b2, both the first end 21b1 and the second end 21b2 have protruding pole ears 21a, 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.

[0107] That is, the height by which the buffer member 3 on the side where the first end 21b1 is provided exceeds the pole piece 21b (as shown by the upper h1 in FIG12 ) is 0 to 5 mm, for example, 0 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, etc., and the height by which the buffer member 3 on the side where the second end 21b2 is provided exceeds the pole piece 21b (as shown by the lower h1 in FIG12 ) is 0 to 5 mm, for example, 0 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, etc. It will be understood that when 0 mm is taken, it is equivalent to exceeding by 0 mm, that is, it is flush with the pole piece.

[0108] It is worth noting that although the height of the buffer member 3 on the side where the first end 21b1 is set exceeding the pole piece 21b and the height of the buffer member 3 on the side where the second end 21b2 is set exceeding the pole piece 21b have the same value range, their specific values ​​may be the same or different.

[0109] Therefore, by limiting the height of the buffer member 3 exceeding the pole piece 21b on the pole ear side of the electrode assembly 21 to a range of 0 to 5 mm, on the one hand, the buffer member 3 can more effectively surround and protect the pole piece 21b, and on the other hand, the height of the buffer member 3 exceeding the pole piece 21b can occupy a smaller space in the shell 1.

[0110] Exemplarily, the first height h1 is 0 to 2 mm, that is, the height of the buffer member 3 on the setting side of the first end 21b1 exceeding the pole piece 21b (as shown in the upper h1 in Figure 12) is 0 to 2 mm, for example, 0 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, etc., and the height of the buffer member 3 on the setting side of the second end 21b2 exceeding the pole piece 21b (as shown in the lower h1 in Figure 12) is 0 to 2 mm, for example, 0 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, etc.

[0111] 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 part of the buffer member 3 that exceeds the pole piece 21b relative to the pole piece 21b can be further reduced while allowing the buffer member 3 to more effectively surround and protect the pole piece 21b.

[0112] For example, with reference to FIG13 , the axial ends of the electrode piece 21b are respectively a first end 21b1 and a second end 21b2. All the tabs 21a in the electrode assembly 21 protrude from the first end 21b1. The height of the buffer member 3 extending beyond the electrode piece 21b on the side where the first end 21b1 is provided is a first height h1. 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 member 3 extending beyond the electrode piece 21b on the side where the second end 21b2 is provided is a second height h2. The second height h2 is 0 to 2 mm, for example, 0 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, etc.

[0113] Therefore, by limiting the height of the buffer member 3 exceeding the pole piece 21b on the pole ear side of the electrode assembly 21 to a range of 0 to 5 mm, and at the same time limiting the height of the buffer member 3 exceeding the pole piece 21b on the non-pole ear side of the electrode assembly 21 to a range of 0 to 2 mm, on the one hand, the buffer member 3 can more effectively surround and protect the pole piece 21b, and on the other hand, the height of the buffer member 3 exceeding the pole piece 21b can occupy less space in the shell 1.

[0114] Exemplarily, the first height h1 is 0 to 2 mm, and the second height h2 is 0 to 0.5 mm, that is, the height of the buffer 3 on the setting side of the first end 21b1 exceeding the pole piece 21b (as shown in the upper h1 in Figure 13) is 0 to 2 mm, for example, 0 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, etc., and the height of the buffer 3 on the setting side of the second end 21b2 exceeding the pole piece 21b (as shown in the lower h2 in Figure 13) 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.

[0115] 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, on the premise that the buffer member 3 can more effectively surround and protect the pole piece 21b, the height space occupied by the part of the buffer member 3 that exceeds the pole piece 21b in the shell 1 can be further reduced.

[0116] In some embodiments of the present application, as shown in Figures 12 and 13 , the difference between the height H2 of the buffer member 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 hardness height of the electrode assembly 21. Typically, the axial height of the separator is greater than the axial height of the electrode piece. Therefore, during processing, the portion of the separator that protrudes beyond the electrode piece is smoothed. After smoothing, the height of the electrode assembly 21 is the hardness height. In the above embodiment, by limiting the difference between the height H2 of the buffer member 3 and the height H3 of the electrode assembly 21 to -2 to 2 mm, i.e., the height difference between the two is within ±2 mm, the height of the buffer member 3 can be close to the hardness height of the electrode assembly 21. For example, the height of the buffer member 3 is greater than the hardness height, but the height difference is 0 to 2 mm, or the height of the buffer member 3 is less than the hardness height, but the height difference is -2 to 0 mm. For example, the height difference between the height of the buffer member 3 and the hardness height of the electrode assembly 21 is -2 mm, -1.5 mm, -1 mm, 0 mm, 1 mm, 1.5 mm, 2 mm, and so on. 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. 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.

[0117] For example, as shown in FIG12 and FIG13 , the difference between the height H2 of the buffer member 3 and the height H3 of the electrode assembly 21 is -0.5 to 0.5 mm. For example, the difference between the height of the buffer member 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 member 3 can be sufficient to fully protect the electrode sheet 21 b from the entire axial height, and on the other hand, the problem of the buffer member 3 exceeding the hard height by too much, resulting in excessive space occupation and affecting the energy density of the battery cell 102, can be avoided.

[0118] In some embodiments of the present application, as shown in FIG5 , the buffer member 3 includes an integrally molded annular buffer sleeve 3a. Thus, the buffer sleeve 3a has no seams along its entire circumference, thereby preventing the buffer sleeve 3a from breaking at the seams, which could cause uneven stress on the electrode assembly 21 at the corresponding breakpoints, resulting in stress boundary points and causing outer electrode fracture. This improves the reliability of the battery cell 102.

[0119] It is worth noting that when the buffer sleeve 3a is an integrally formed ring, the order of assembling 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 first placed in the buffer sleeve 3a, or in other words, the buffer sleeve 3a can be first placed on the outside of the battery cell 2, and then the pre-assembled battery cell 2 and the buffer sleeve 3a can be installed together in the housing 1. Alternatively, for example, the buffer sleeve 3a can be first installed in the housing 1, and then the battery cell 2 can be installed in the housing 1, so that the battery cell 2 is installed in the buffer sleeve 3a in the housing 1.

[0120] In some embodiments of the present application, when the buffer sleeve 3a is an integrally formed ring sleeve shape and the battery cell 2 includes multiple electrode assemblies 21, in some specific examples, as shown in Figure 7, a buffer sleeve 3a can be separately provided outside each electrode assembly 21, or, in other specific examples, as shown in Figure 6, at least two electrode assemblies 21 can be jointly sheathed in the same buffer sleeve 3a.

[0121] For example, as shown in FIG7 , when each electrode assembly 21 is individually sheathed with a buffer sleeve 3a, the number of buffer sleeves 3a is the same as the number of electrode assemblies 21, and they are arranged one by one. In this way, when multiple electrode assemblies 21 are combined, the buffer member 3 can still surround the entire circumference of the battery cell 2 in the cross section of the electrode assembly 21. 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. As shown in FIG10 , the upper, left, and right portions of the buffer sleeve 3a disposed outside the upper electrode assembly 21 and the lower, left, and right portions of the buffer sleeve 3a disposed outside the lower electrode assembly 21 together surround the entire circumference of the battery cell 2 (i.e., the two electrode assemblies 21). Thus, by individually sheathing each electrode assembly 21 with a buffer sleeve 3a, each electrode assembly 21 can be supported by the buffer sleeve 3a throughout its circumference, thereby improving the force balance effect of each electrode assembly 21, effectively protecting each electrode assembly 21, and reducing the mutual compression between adjacent electrode assemblies 21.

[0122] For example, as shown in Figures 6 and 11, 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. Specifically, when at least two electrode assemblies 21 are collectively sheathed in the same buffer sleeve 3a, there can be one or more buffer sleeves 3a. When there is only one buffer sleeve 3a, all electrode assemblies 21 can be collectively sheathed in the same buffer sleeve 3a (for example, as shown in Figure 6), thereby further reducing the number of buffer sleeves 3a and the assembly process, 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 sheathed with an electrode assembly 21, and at least one buffer sleeve 3a is simultaneously sheathed with more than one electrode assembly 21, thereby achieving flexible configuration.

[0123] In some embodiments, such as shown in FIG11 , when at least two electrode assemblies 21 are collectively sheathed in the same buffer sleeve 3a, a buffer pad 3b may be further provided between the multiple electrode assemblies 21 located in the same buffer sleeve 3a. In this way, by providing a buffer pad 3b between two adjacent electrode assemblies 21, each electrode assembly 21 may be supported by the buffer member 3 throughout its entire periphery, thereby reducing the mutual extrusion between the two adjacent electrode assemblies 21 and improving the protection of each electrode assembly 21.

[0124] For example, in other embodiments, as shown in FIG6 , when at least two electrode assemblies 21 are encased within the same buffer sleeve 3a, the buffer pad 3b provided between two adjacent electrode assemblies 21 can be eliminated. This means that the multiple electrode assemblies 21 encased within the same buffer sleeve 3a are in direct contact with each other, or in other words, no buffer pad 3b is provided between the multiple electrode assemblies 21 within the same buffer sleeve 3a. In this case, the space occupied by the buffer pad 3b can be reduced, thereby increasing the amount of electrolyte injected or increasing the number of turns of the electrode assembly 21, thereby improving the volumetric energy density of the battery cell 102.

[0125] For example, as shown in Figure 11, the buffer sleeve 3a and the buffer pad 3b are integrally formed, which is convenient for processing and can avoid slits at the connection between the buffer sleeve 3a and the buffer pad 3b, which causes the electrode assembly 21 to be subjected to uneven force 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.

[0126] 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, etc.

[0127] 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. This reduces the mutual compression between two adjacent electrode assemblies 21 and improves the uniformity of force applied to each electrode assembly 21 throughout its entire circumference. It also reduces the space occupied by the buffer pad 3b, facilitating increased electrolyte injection, or increasing the number of turns of the electrode assembly 21, thereby improving the volumetric energy density of the battery cell 102.

[0128] In some embodiments of the present application, as shown in FIG11 , the portion of the surface of the buffer member 3 that faces the housing 1 matches the shape of the inner surface of the housing 1. Thus, the buffer member 3 can be fully supported by the housing 1, thereby improving the reliability of the buffer member 3 supporting the battery cell 2 at various locations. This allows the buffer member 3 to more reliably and effectively balance the forces acting on the electrode assembly 21, reducing the risk of fractures caused by stress boundary points in the electrode assembly 21.

[0129] Exemplarily, as shown in FIG11 , 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 entire outer circumference of the buffer sleeve 3a faces the shell 1 and matches the shape of the inner surface of the shell 1. Exemplarily, as shown in FIG7 , when the battery cell 2 includes multiple electrode assemblies 21, and each electrode assembly 21 is individually sheathed with a buffer sleeve 3a, the portion of the outer circumference of each buffer sleeve 3a facing the shell 1 matches the shape of the inner surface of the corresponding position of the shell 1. For example, as shown in FIG7 , the upper, left, and right portions of the outer circumference of the buffer sleeve 3a sheathed on the upper electrode assembly 21 and the lower, left, and right portions of the outer circumference of the buffer sleeve 3a sheathed on the lower electrode assembly 21 all face the shell 1 and match the shape of the inner surface of the shell 1.

[0130] In some embodiments of the present application, as shown in FIG11 , the portion of the surface of the buffer member 3 facing the electrode assembly 21 matches the outer surface shape of the electrode assembly 21. As a result, the entire circumference of the battery cell 2 can be fully supported by the buffer member 3, thereby improving the uniformity of the force applied to the entire circumference of the battery cell 2 and reducing the risk of fracture at stress boundary points formed on the outer electrode sheets of the battery cell 2.

[0131] For example, as shown in FIG11, 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 circumferential surface 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. 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, as shown in FIG7, when the battery cell 2 includes multiple electrode assemblies 21, and each electrode assembly 21 is separately sheathed with a buffer sleeve 3a, the inner circumferential surface of each buffer sleeve 3a faces the outer surface of the electrode assembly 21 it encloses, and matches the outer surface shape of the corresponding electrode assembly 21.

[0132] In some embodiments of the present application, as shown in Figure 5, 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. Normally, the main body 211 is relatively flat and closer to the shell 1, while the corner portion 212 is arc-shaped and farther away from the shell 1. Setting the thickness of the second part 33 to be greater than the thickness of the first part 32 can better match the empty space between the shell 1 and the battery cell 2, so that after the battery cell 102 is assembled, the first part 32 and the second part 33 are basically uncompressed, so as to provide a relatively uniform support force to the electrode assembly 21 during the subsequent charging and discharging process of the electrode assembly 21. Moreover, it will not occur that the shell 1 needs to be enlarged or the electrode assembly 21 needs to be reduced because the thickness of the first part 32 is greater than the thickness of the second part 33, so that the battery cell 102 can maintain a higher volume energy density while maintaining its current smaller volume.

[0133] In some embodiments of the present application, the compression rate of the second portion 33 is less than or equal to the compression rate of the first portion 32. When the compression rates of the first and second portions 32 are the same, the materials of the two portions can be identical, facilitating processing. When the compression rate of the second portion 33 is less than that of the first portion 32, this indicates that under the same external force, the volume of the second portion 33 decreases less than that of the first portion 32. Because the main body 211 is closer to the housing 1 and can receive support from the housing 1 more readily, while the corner portion 212 is farther away from the housing 1 and cannot receive support from the housing 1 in a timely manner, by setting the compression rate of the second portion 33 between the corner portion 212 and the housing 1 to be relatively low, the hardness of the second portion 33 can be relatively high, providing sufficient support to the corner portion 212 in a timely manner. This ensures that the force applied to the entire electrode assembly 21 is relatively uniform, thereby more effectively alleviating the problem of electrode cracking.

[0134] It is understood that the "compression rate of a material" refers to the degree to which the material's volume decreases under the action of an external force. Compression rate is an important indicator for measuring a material's ability to deform after being subjected to a force and is also one of the key parameters of a material's mechanical properties. The compression rate of a material is related to its properties and varies from material to material. For example, when the materials are the same, the greater the porosity, the higher the compression rate, while the smaller the porosity, the lower the compression rate. Therefore, the compression rate of the first portion 32 and the second portion 33 can be adjusted by adjusting the material or parameters such as porosity.

[0135] It is understood that the method of measuring the compressibility of materials is well known to those skilled in the art. For example, a 1mm thick sample can be cut into 50*100mm 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.

[0136] 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 was found that the compression rate of the buffer 3 has an impact on the breakage and wrinkling of the electrode piece. The buffer 3 has a high compression rate and is easy to compress. The expansion space of the electrode assembly 21 is large, and the electrode piece is prone to breakage, but not prone to wrinkling. On the other hand, the buffer 3 has a low compression rate and is not easy to compress. The expansion space of the electrode assembly 21 is small, and the electrode piece is prone to wrinkling, but relatively not prone to breakage.

[0137] 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 the 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, which can better take into account the reduction of the risk of pole piece fracture and the improvement of the problem of pole piece wrinkling. For another example, when the compression rate of the 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.

[0138] 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 easily reduced to that of the first part 32, thereby effectively improving the cracking problem of the electrode. 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 portion 32 is 30 kg / m 3 , 40kg / m 3 , 50kg / m 3 、60kg / m3 , 70kg / m 3 、80kg / m 3 , 90kg / m 3 , 100kg / m 3 、110kg / m 3 wait.

[0139] For example, the density of the second portion 33 is 70-110 kg / m 3 The density of the first part 32 is 40-60 kg / m 3 Therefore, it is easier to select a value within the above range to achieve a density of the second part 33 greater than the density of the first part 32, thereby easily achieving a compression rate of the second part 33 less than the compression rate of the first part 32, thereby effectively improving the cracking problem of the electrode. For example, the density of the second part 33 is 70kg / m 3 、80kg / m 3 , 90kg / m 3 , 100kg / m 3 、110kg / m 3 etc., the density of the first portion 32 is 40 kg / m 3 , 50kg / m 3 、60kg / m 3 wait.

[0140] For example, a material having a smaller adsorption force on the electrolyte than the adsorption force of the isolation film in the core can be selected, such as but not limited to PE (polyethylene), PP (polypropylene), PET (polyethylene terephthalate), PC (polycarbonate), PPS (polyphenylene sulfide), glass fiber, carbon fiber, and multiple composite materials.

[0141] According to some embodiments of the present application, a battery 100 is provided, comprising a battery cell 102 according to any of the above-described solutions. Because the reliability of the battery cell 102 according to the embodiments of the present application is improved, the reliability of the battery 100 is improved. It is worth noting that the battery 100 according to the embodiments of the present application may or may not include a housing 101.

[0142] Exemplarily, the battery 100 further includes a busbar component, and at least two of the battery cells 102 are electrically connected via the busbar component. This allows for the series and / or parallel connection of multiple battery cells 102. 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 via one busbar component, while the cathode of the battery cell 102 is connected to the anode of the previous battery cell 102 via another busbar component.

[0143] The present application also provides an electrical device comprising a battery cell 102 according to any of the aforementioned solutions. Battery 100 is used to provide power to the electrical device. The electrical device can be any of the aforementioned devices or systems utilizing battery cell 102. The improved reliability of battery cell 102 improves the electrical performance of the electrical device.

[0144] 6 , a battery cell 102 according to a specific embodiment of the present application will be described.

[0145] The battery cell 102 includes a housing 1, a battery cell 2, and a buffer 3. The housing 1 defines a housing cavity 13. The battery cell 2 is disposed within the housing cavity 13 and includes two electrode assemblies 21. The buffer 3 is disposed within the housing cavity 13. The buffer 3 is in the shape of an integral ring. In the cross-section of the electrode assembly 21, the buffer 3 surrounds the entire circumference of the battery cell 2, allowing the buffer 3 to be positioned between the housing 1 and the battery cell 2. The outer circumference of the buffer 3 matches the inner surface of the housing 1, and the inner circumference of the buffer 3 matches the outer surface 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 housing 1, and a second portion 33 located between the corner portion 212 and the housing 1. The second portion 33 is thicker than the first portion 32. The buffer member 3 is an elastic member containing a pore 31, and the pore 31 is connected to the accommodating cavity 13. The two side surfaces of the buffer member 3 along the axial direction of the electrode assembly 21 are axial end surfaces. The pore 31 includes a first through hole 311 that penetrates the two side axial end surfaces of the buffer member 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 member 3 is greater than the height of the electrode piece in the electrode assembly 21, and the height of the buffer member 3 is close to the hard height of the electrode assembly 21.

[0146] In the above technical solution, when the electrode assembly 21 expands, a full circle of buffer parts 3 are provided between the outer surface of the battery cell 2 and the shell 1, so that direct interaction between the battery cell 2 and the shell 1 can be avoided. 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, the force uniformity of the entire circumference of the electrode assembly 21 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 electrode piece at the stress boundary point, and improving the problems of lithium deposition or internal short caused by the fracture of the electrode piece, which is beneficial to improving the reliability and cycle life of the battery cell 102.

[0147] Furthermore, because the pores 31 within the buffer member 3 communicate with the accommodating cavity 13, the pores 31 can be utilized to store electrolyte. This increases the amount of electrolyte injected into the housing 1 compared to a solid or sealed buffer member, thereby improving the cycle life of the battery cell 102. Furthermore, because the buffer member 3 includes pores 31 communicating with the accommodating cavity 13, when the buffer member 3 is squeezed by the expanding electrode assembly 21, the pores 31 within the buffer member 3 are squeezed to expel electrolyte or gas, resulting in compression of the buffer member 3 rather than extension along the axial direction of the electrode assembly 21 (e.g., the first direction F1 described above). Consequently, the axial extension of the buffer member 3 prevents compression of the axial separator of the electrode assembly 21, thereby preventing internal shorts between the positive and negative electrodes. This further improves the reliability of the battery cell 102.

[0148] In addition, since the buffer 3 is in the shape of an integral ring, there are no seams around the buffer 3, which can prevent the buffer 3 from breaking at the seams, causing the electrode assembly 21 to be unevenly stressed at the corresponding fracture point, generating stress boundary points, 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 put on the outside of the battery cell 2 first, and then the pre-assembled battery cell 2 and the buffer 3 can be installed together in the shell 1. Or, for example, the buffer 3 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 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.

[0149] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0150] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A battery cell, wherein: include: a housing, wherein a receiving cavity is defined in the housing; A battery cell, the battery cell being disposed in the accommodating cavity and comprising at least one electrode assembly; A buffer member is arranged 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, wherein: Both side surfaces of the buffer member along the axial direction of the electrode assembly are axial end surfaces, and the pore includes first through holes penetrating the both side axial end surfaces of the buffer member.

3. The battery cell according to claim 2, wherein: The electrode assembly includes a main body and corner portions located at both ends of the main body, and the first through holes are multiple and arranged around the corner portions.

4. The battery cell according to claim 2 or 3, wherein: The pore further includes a second through hole, which passes through the outer circumferential surface and / or the inner circumferential surface of the buffer component and is connected to the first through hole.

5. The battery cell according to any one of claims 1 to 4, wherein: Along the axial direction of the electrode assembly, the height of the buffer member is greater than the height of the electrode piece in the electrode assembly; The two axial ends of the buffer member respectively extend beyond the two axial ends of the pole piece; or, one axial end of the buffer member is flush with the corresponding axial end of the pole piece, and the other axial end of the buffer member extends beyond the corresponding axial end of the pole piece. The battery cell according to claim 5 , wherein: 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 tabs, and the height of the buffer member on the setting side of the first end and the setting side of the second end protruding from the pole piece is a first height, and the first height is 0 to 5 mm; Alternatively, all the tabs in the electrode assembly protrude from the first end, the height of the buffer component on the side where the buffer component is set at the first end 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 buffer component is set at the second end 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, wherein: The first height is 0-2 mm, and the second height is 0-0.5 mm.

8. The battery cell according to any one of claims 5 to 7, wherein: The difference between the height of the buffer member and the height of the electrode assembly is -2 to 2 mm.

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

10. The battery cell according to any one of claims 1 to 9, wherein: The buffer component includes a buffer sleeve in an integrally formed ring shape.

11. The battery cell according to claim 10, wherein: The battery core includes a plurality of electrode assemblies, and each electrode assembly is separately sheathed with a buffer sleeve.

12. The battery cell according to claim 10, wherein: The battery core includes 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, wherein: All the electrode assemblies are collectively sheathed in the same buffer sleeve.

14. The battery cell according to claim 12 or 13, wherein: The multiple 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, wherein: The buffer component further includes a buffer pad, which is sleeved in the same buffer sleeve and is provided between two adjacent electrode assemblies.

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

17. The battery cell according to claim 15 or 16, wherein: 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.

18. The battery cell according to any one of claims 1 to 17, wherein: A portion of the surface of the buffer member facing the housing matches the shape of the inner surface of the housing.

19. The battery cell according to any one of claims 1 to 18, wherein: 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 any one of claims 1 to 19, wherein: 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, wherein: The compression rate of the second portion is less than or equal to the compression rate of the first portion.

22. The battery cell according to claim 21, wherein 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, wherein: 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, wherein: The invention comprises a battery cell according to any one of claims 1 to 23.

25. An electrical device, wherein: The invention comprises a battery cell according to any one of claims 1 to 23.

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