Buffer member, battery cell, battery, and electrical apparatus

Abstract

A buffer member (10), a battery cell (100), a battery (1000), and an electrical apparatus (2000). The buffer member (10) is used inside the battery cell (100), and the battery cell (100) comprises an electrode assembly (20). The buffer member (10) comprises: a first surface (11) and a second surface (12) which are arranged opposite to each other; and through channels (14) penetrating through the first surface (11) and the second surface (12), wherein the buffer member (10) can be compressed for buffering the expansion of the electrode assembly (20), and the through channels (14) are used for increasing the compressibility of the buffer member (10).

Description

Buffers, battery cells, batteries and electrical devices Technical Field

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

[0002] During the charge and discharge cycle of the electrode assembly, the electrode will expand repeatedly. The expansion force of the electrode acts on the shell, causing the shell to expand and deform, resulting in the electrode being easily wrinkled, causing lithium or sodium deposition problems in the electrode assembly during the cycle.

[0003] In the related art, a buffer pad is often placed inside the battery cell. However, the structural design of the buffer pad is unreasonable, making it difficult to solve the problem of lithium or sodium deposition caused by wrinkling of the electrode sheet. Moreover, in the later stage of the cycle of the electrode assembly, the expansion force is too large and the electrode sheet is wrinkled, resulting in serious lithium or sodium deposition problems, affecting the performance and service life of the battery cell.

[0004] Summary of the Invention

[0005] The embodiments of the present application provide a buffer, a battery cell, a battery, and an electrical device. The compressibility of the buffer is increased, and the occupied space can be reduced to reduce the expansion force.

[0006] In a first aspect, an embodiment of the present application provides a buffer member for use inside a battery cell, wherein the battery cell includes an electrode assembly, and the buffer member includes: a first surface and a second surface arranged opposite to each other; a through channel arranged through the first surface and the second surface; wherein the buffer member is compressible to buffer the expansion of the electrode assembly, and the through channel is used to increase the compressibility of the buffer member.

[0007] In the above technical solution, the provision of a buffer can provide better support for the electrode assembly when expansion is small, reducing electrode sheet deformation and improving the wrinkling of the electrode sheet caused by electrode assembly expansion, thereby alleviating the problem of lithium or sodium deposition during the cycle of the electrode assembly and improving the performance of the battery cell. Furthermore, the provision of a through-channel can increase the compressibility of the buffer, so that when the electrode assembly expands significantly, the buffer can be effectively compressed to reduce the space occupied. The buffering effect balances the expansion and accommodates the deformation of the electrode assembly. The expansion force is not too strong, which may cause lithium or sodium deposition at the interface, and the electrode sheet is not easily deformed, which may cause lithium or sodium deposition, thereby effectively improving the cycling performance of the battery cell.

[0008] In some embodiments, the buffer member has a pressure-bearing surface facing toward or facing away from the electrode assembly, and the first surface and / or the second surface is the pressure-bearing surface.

[0009] In the above technical solution, a surface with an end opening that passes through the channel is formed as a pressure-bearing surface, so that the actual force-bearing area of ​​the pressure-bearing surface is reduced and the force-bearing surface pressure per unit area is increased, thereby more effectively improving the compressibility of the buffer and solving the problems of large expansion force in the later stage of the cycle and volume occupation of the buffer.

[0010] In some embodiments, the total opening area of ​​the end openings of the through channels formed on the surface on the same side is S1, and the area of ​​the corresponding surface is S2, and S1 and S2 satisfy: S1 / S2 is greater than or equal to 5% and less than or equal to 80%.

[0011] In the above technical solution, the number and volume of the through-channels are reasonable, so as to take into account both the supporting effect of the buffer member on the electrode assembly and the effect of improving the compressibility.

[0012] In some embodiments, the S1 and the S2 further satisfy: S1 / S2 is greater than or equal to 20% and less than or equal to 50%.

[0013] In the above technical solution, the supporting effect and compressibility of the buffer component can be further improved.

[0014] In some embodiments, the equivalent diameter of the end opening of the through-channel is greater than or equal to 2 mm and less than or equal to 20 mm.

[0015] In the above technical solution, the equivalent diameter of the end opening will not be too large or too small, which effectively improves the overall structural strength of the buffer and improves the structural stability to improve the supporting capacity; it is also beneficial to effectively improve the compressibility of the buffer, thereby better meeting the buffering needs in the later stage of the cycle.

[0016] In some embodiments, the equivalent diameter of the end opening is greater than or equal to 5 mm and less than or equal to 10 mm.

[0017] In the above technical solution, the supporting capacity and compressibility of the buffer component can be further improved.

[0018] In some embodiments, there are multiple through-channels, wherein at least two of the through-channels cross and communicate with each other.

[0019] In the above technical solution, multiple through channels make the hole structure relatively more evenly distributed on the buffer, which is beneficial to improving the compressibility uniformity and support stability of different areas of the buffer, and the cross-arrangement method is more effective in improving the compressibility rate of the buffer.

[0020] In some embodiments, there are multiple through-channels, and the multiple through-channels are arranged at intervals.

[0021] In the above technical solution, multiple through channels make the hole structure relatively more evenly distributed on the buffer, which is beneficial to improving the compressibility uniformity and support stability of different areas of the buffer, and the spaced arrangement method can not only improve the uniformity of the distribution of the through channels on the buffer to improve the support effect of the buffer, but also reduce the processing difficulty of the through channels.

[0022] In some embodiments, the plurality of through channels all extend along a first direction, and the plurality of through channels are arranged in an array perpendicular to the first direction.

[0023] In the above technical solution, the array arrangement makes the arrangement of multiple through-channels more uniform, and the effect of improving support stability and compressibility is also more uniform.

[0024] In some embodiments, the buffer member includes a first buffer region and a second buffer region, and the compressibility of the second buffer region is greater than the compressibility of the first buffer region at the same pressure.

[0025] In the above technical solution, when the buffer part is used for a battery cell, the first buffer area and the second buffer area can correspond to different areas of the electrode assembly respectively, so as to balance the expansion force differences in different areas of the battery cell according to the expansion conditions of different areas of the electrode assembly, which is beneficial to improving the interface lithium or sodium precipitation problem caused by uneven expansion force distribution and improving the long-term cycle stability of the battery cell.

[0026] In some embodiments, the through channel is provided in the second buffer region.

[0027] In the above technical solution, while balancing the differences in expansion forces in different areas, it is beneficial to reduce the number of through-channels and improve the supporting capacity of the buffer.

[0028] In some embodiments, the total volume of the through-channels in the first buffer region is smaller than the total volume of the through-channels in the second buffer region.

[0029] In the above technical solution, while balancing the differences in expansion forces between different regions, the first buffer region can also better adapt to the expansion of the electrode assembly in the later stage of the cycle.

[0030] In some embodiments, the equivalent aperture of the end opening of the through channel is d, and in the first buffer area, the spacing between the end openings of two adjacent through channels is greater than or equal to 2d and less than or equal to 4d, and in the second buffer area, the spacing between the end openings of two adjacent through channels is greater than or equal to d / 3 and less than or equal to 2d.

[0031] In the above technical solution, the through-channels of the second buffer region are denser than those of the first buffer region, resulting in a higher compressibility of the second buffer region than that of the first buffer region. Furthermore, the end openings of each buffer region are not arranged too densely, thereby weakening the structural strength of the corresponding buffer region, thus ensuring the supporting stability of the corresponding buffer region; and the end openings are not arranged too sparsely, thereby reducing the compressibility and failing to meet the requirements of the later stages of the cycle.

[0032] In some embodiments, the compressibility of the first buffer area under a pressure of 0.5 MPa is not less than 40%, the compressibility under a pressure of 0.8 MPa is not less than 60%, and the compressibility under a pressure of 1 MPa is not less than 85%; the compressibility of the second buffer area under a pressure of 0.5 MPa is not less than 20%, the compressibility under a pressure of 0.8 MPa is not less than 30%, and the compressibility under a pressure of 1 MPa is not less than 50%.

[0033] In the above technical solution, the first buffer region and the second buffer region can effectively balance the expansion force differences between different regions of the electrode assembly throughout the entire cycle, thereby improving the long-term cycle stability of the battery cell.

[0034] In some embodiments, the through channel penetrates the buffer member along a first direction, there are two first buffer regions, and the two first buffer regions are respectively located on both sides of the second buffer region along a second direction, and the first direction intersects with the second direction.

[0035] In the above technical solution, the above arrangement of the first buffer area and the second buffer area can meet the thickness difference of small expansion force at both ends and large expansion force in the middle in the second direction. The corresponding electrode assembly can adopt a structure with the second electrode area in the middle and the first electrode areas on both sides in the second direction, so that both ends of the electrode assembly can fully exert their electrical performance.

[0036] In a second aspect, an embodiment of the present application further provides a battery cell, comprising a housing, an electrode assembly, and the aforementioned buffer component, wherein the buffer component and the electrode assembly are both disposed within the housing.

[0037] In some embodiments, the electrode assembly includes a plurality of pole pieces arranged in a wound manner and the outer peripheral surface of the electrode assembly includes a straight portion and a bend portion connected to the end of the straight portion, and at least one of the straight portion and the bend portion is arranged opposite to the buffer member.

[0038] In the above technical solution, the buffer component can buffer and support at least one of the straight portion and the curved portion, thereby reducing the risk of bridge breakage and lithium deposition of the electrode assembly.

[0039] In some embodiments, the electrode assembly includes a plurality of positive electrode sheets and a plurality of negative electrode sheets stacked along a first direction, and the buffer is disposed opposite to a surface of at least one side of the electrode assembly along the first direction.

[0040] In the above technical solution, the buffer component can effectively buffer and support the laminated electrode assembly, and the buffer component requires a small area and has a low cost.

[0041] In some embodiments, the electrode assemblies are arranged in a plurality along a first direction, the buffer member is disposed between two adjacent electrode assemblies, and / or the buffer member is disposed between the electrode assembly and the shell.

[0042] In some embodiments, the end opening of the through channel is formed on the pressure-bearing surface of the buffer component, and the electrode stacking direction of the electrode assembly in the area opposite to the pressure-bearing surface is perpendicular to the pressure-bearing surface.

[0043] In the above technical solution, during use, the electrode is more likely to expand along the stacking direction. The stacking direction of the electrode in the area opposite to the pressure-bearing surface is perpendicular to the pressure-bearing surface, so that the pressure-bearing surface can more fully provide cushioning and support to the electrode, thereby improving the effect of reducing electrode wrinkling.

[0044] In the above technical solution, the buffer member can not only support and buffer the electrode assembly, but also separate the electrode assembly from the shell or adjacent electrode assemblies. After the electrode assembly expands, it is not easy to squeeze the shell or the electrode assemblies squeeze each other.

[0045] In some embodiments, the buffer member and the electrode assembly are arranged along a first direction, and surfaces of the electrode assembly on both sides along the first direction are surfaces with the largest areas.

[0046] In this technical solution, by positioning the buffer member opposite the largest surface of the electrode assembly, the buffer member can provide support and compress in areas of the electrode assembly more prone to expansion and deformation, effectively reducing expansion forces. This also helps reduce the amount of buffer member used, lowering costs, reducing space requirements, and increasing energy density.

[0047] In some embodiments, the buffer member is arranged on the side of the electrode assembly along the first direction, the electrode assembly includes an electrode body and a pole ear arranged at the end of the electrode body, the electrode body includes a first electrode area and a second electrode area, the number of pole piece layers of the first electrode area along the first direction is less than the number of pole piece layers of the second electrode area along the first direction, the buffer member has a first buffer area and a second buffer area, the first buffer area is arranged corresponding to the first electrode area, and the second buffer area is arranged corresponding to the second electrode area, and the compressibility of the first buffer area is less than the compressibility of the second buffer area.

[0048] In the above technical solution, the first electrode region squeezes the first buffer region, and the second electrode region squeezes the second buffer region, effectively balancing the expansion force difference corresponding to the first electrode region and the second electrode region, improving the problem of interface lithium or sodium deposition caused by uneven expansion force of the battery body, balancing the thickness difference between the first electrode region and the second electrode region, and improving the long-term cycle stability of the battery body.

[0049] In some embodiments, there are two first buffer areas and the two first buffer areas are respectively located on both sides of the second buffer area along the second direction, the first direction intersects with the second direction, and in the second direction, the size of the first buffer area is H1, the size of the second buffer area is H2, and the size of the electrode body is H3, wherein H3-(H2+2H1) is greater than or equal to -2.5 mm and less than or equal to 14.5 mm, and H1 is greater than or equal to 3.5 mm and less than or equal to 5.5 mm.

[0050] In the above technical solution, the buffer can provide stable support to the area of ​​the electrode body that is prone to expansion, and provide more precise support and buffering for areas with larger and smaller expansion forces, and is conducive to reducing the volume of the buffer, reducing occupied space and cost.

[0051] In some embodiments, H3-(H2+2H1) is greater than or equal to 6.5 mm and less than or equal to 10 mm.

[0052] In the above technical solution, the overall support and buffering effect of the buffer component on the electrode body can be further improved, while the effect of reducing the space occupied by the buffer component is better.

[0053] In some embodiments, the electrode assembly includes a positive electrode sheet, a negative electrode sheet, and an isolation membrane arranged between the positive electrode sheet and the negative electrode sheet, and the first electrode region includes the positive electrode sheet, the isolation membrane, and the negative electrode sheet arranged in a stacked manner; the second electrode region includes the negative electrode sheet and the isolation membrane arranged in a stacked manner, or the second electrode region includes the negative electrode sheet.

[0054] In the above technical solution, the negative electrode plate has a larger size, which is conducive to the negative electrode plate fully receiving the lithium ions provided by the positive electrode plate, thereby giving full play to the electrical properties of the positive electrode material and improving the lithium plating problem.

[0055] In some embodiments, the buffer member is arranged on the side of the electrode assembly along the first direction, the electrode assembly includes an electrode body and a pole ear arranged at the end of the electrode body, the electrode body includes a third electrode region and a fourth electrode region, the thickness of the pole piece of the electrode assembly in the third electrode region is less than the thickness in the fourth electrode region, the buffer member has a third buffer region and a fourth buffer region, the third buffer region is arranged corresponding to the third electrode region, the fourth buffer region is arranged corresponding to the fourth electrode region, and the compressibility of the third buffer region is less than the compressibility of the fourth buffer region.

[0056] In the above technical solution, by placing the third buffer region with a small compressibility opposite to the third electrode region with a smaller expansion, and the fourth buffer region with a large compressibility opposite to the fourth electrode region with a larger expansion, the third electrode region squeezes the third buffer region, and the fourth electrode region squeezes the fourth buffer region, effectively balancing the expansion force difference corresponding to the third electrode region and the fourth electrode region, improving the problem of interface lithium or sodium deposition caused by uneven expansion force of the battery cell, balancing the thickness difference between the third electrode region and the fourth electrode region, and improving the long-term cycle stability of the battery cell.

[0057] In some embodiments, there are two third buffer areas and the two third buffer areas are respectively located on both sides of the fourth buffer area along the second direction, the first direction intersects with the second direction, and in the second direction, the size of the third buffer area is H4, the size of the fourth buffer area is H5, and the size of the electrode body is H3, wherein H3-(H5+2H4) is greater than or equal to -2.5mm and less than or equal to 20mm, and H4 is greater than or equal to 1mm and less than or equal to 10mm.

[0058] In the above technical solution, within the above range of values, the buffer can provide stable support to areas of the electrode body prone to expansion, and more precisely support and cushion areas with greater and lesser expansion forces. This also helps reduce the volume of the buffer, reducing occupied space and cost. This also maintains the electrical performance of the electrode assembly and reduces active material accumulation during the rolling process.

[0059] In some embodiments, H3-(H5+2H4) is greater than or equal to 6.5 mm and less than or equal to 13 mm.

[0060] In the above technical solution, the overall support and buffering effect of the buffer component on the electrode body can be further improved, while the effect of reducing the space occupied by the buffer component is better.

[0061] In a third aspect, an embodiment of the present application further provides a battery comprising the above-mentioned battery cell.

[0062] In a fourth aspect, an embodiment of the present application further provides an electrical device comprising the above-mentioned battery, wherein the battery is used to provide electrical energy to the electrical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figures 1 and 2 are schematic structural diagrams of a battery cell provided in an embodiment of the present application;

[0064] FIG3 is a cross-sectional view of a battery cell provided by some embodiments of the present application along the line AA in FIG2 ;

[0065] FIG4 is a cross-sectional view of a battery cell provided by some embodiments of the present application along the direction indicated by line BB in FIG2 ;

[0066] FIG5 is a cross-sectional view of a battery cell provided in some other embodiments of the present application along the direction indicated by line BB in FIG2 ;

[0067] FIG6 is a cross-sectional view of a battery cell provided by some other embodiments of the present application along the direction indicated by line BB in FIG2 ;

[0068] FIG7 is a schematic structural diagram of a buffer member provided in the first embodiment of the present application;

[0069] FIG8 is a schematic structural diagram of a buffer member provided in a second embodiment of the present application;

[0070] FIG9 is a schematic structural diagram of a buffer member provided in a third embodiment of the present application;

[0071] FIG10 is a schematic structural diagram of a buffer member provided in a fourth embodiment of the present application;

[0072] FIG11 is a schematic structural diagram of a buffer member provided in a fifth embodiment of the present application;

[0073] FIG12 is a schematic structural diagram of a buffer member provided in a sixth embodiment of the present application;

[0074] FIG13 is a schematic structural diagram of a buffer member and an electrode assembly provided in a seventh embodiment of the present application;

[0075] FIG14 is a schematic structural diagram of a buffer member provided in a seventh embodiment of the present application;

[0076] FIG15 is a schematic structural diagram of a buffer member provided in an eighth embodiment of the present application;

[0077] FIG16 is a schematic diagram of a partial structure of an electrode assembly provided in an embodiment of the present application;

[0078] FIG17 is a schematic diagram of a battery provided in an embodiment of the present application;

[0079] FIG18 is a schematic diagram of a vehicle provided in an embodiment of the present application.

[0080] Figures and symbols: Battery 1000; Electrical device 2000; Battery cell 100; Buffer 10; First surface 11; Second surface 12; Pressure-bearing surface 13; Through channel 14; First buffer region 15; Second buffer region 16; Third buffer region 17; Fourth buffer region 18; Electrode assembly 20; Electrode body 21; First electrode region 211; Second electrode region 212; Tab 22; Positive electrode sheet 23; Negative electrode sheet 24; Isolation membrane 25; Straight portion 26; Bend portion 27; Shell 30; First direction F1; Second direction F2; Third direction F3. DETAILED DESCRIPTION

[0081] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0082] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0083] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0084] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0085] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0086] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0087] The term "plurality" used in this application refers to two or more (including two).

[0088] In this application, a battery 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 battery pack. Some batteries may include a housing that encloses one or more battery cells or multiple battery modules. The housing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells. Of course, some batteries may not include such a housing and may be installed directly in the battery compartment of the electrical device.

[0089] In this application, battery cells may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, etc., and the embodiments of this application do not limit this. Battery cells may be cylindrical, flat, rectangular, or other shapes, etc., and the embodiments of this application do not limit this. Battery cells are generally divided into three types based on the packaging method: cylindrical battery cells, prismatic battery cells, and soft-pack battery cells, and the embodiments of this application do not limit this.

[0090] For example, a battery cell may include a shell, an electrode assembly and an electrolyte, and the shell is used to contain the electrode assembly and the electrolyte. The electrode assembly is formed by winding or stacking a positive electrode sheet, a negative electrode sheet and a separator. The battery cell mainly relies on the movement of metal ions between the positive electrode sheet and the negative electrode sheet to work. The positive electrode sheet includes a positive electrode collector and a positive electrode active material layer. The positive electrode active material layer is coated on the surface of the positive electrode collector. The positive electrode collector not coated with the positive electrode active material layer protrudes from the positive electrode collector coated with the positive electrode active material layer, and the positive electrode collector not coated with the positive electrode active material layer serves as the positive electrode tab. Taking lithium-ion batteries as an example, the material of the positive electrode collector can be aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide, etc.

[0091] The negative electrode sheet consists of 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 negative current collector uncoated with the negative active material layer protrudes from the negative current collector coated with the negative active material layer. The negative 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, silicon, or other materials. To ensure that high currents can pass without melting, multiple positive electrode tabs are stacked together, and multiple negative electrode tabs are stacked together.

[0092] The material of the isolation film may be PP (polypropylene) or PE (polyethylene), etc. In addition, the electrode assembly may be a wound structure or a laminated structure, but the embodiments of the present application are not limited thereto.

[0093] Battery cells can be equipped with terminals and other components connected to the tabs, serving as electrical connections. Furthermore, they can have pressure relief features. When the internal pressure in a battery cell becomes excessive (e.g., due to thermal runaway), these features release substances (e.g., gas, liquid, particulate matter, etc.) from the cell to reduce the internal pressure. This prevents excessive internal pressure from causing dangerous accidents such as explosions. For example, these relief features can be explosion-proof valves, explosion-proof discs, and the like.

[0094] During the charge and discharge cycles of an electrode assembly, the electrode sheets repeatedly expand. This expansion force acts on the housing, causing it to expand and deform. The larger the main surface of the housing, the more severe the deformation. This can lead to wrinkling of the electrode sheets, causing lithium or sodium deposition during cycling.

[0095] In some related technologies, a buffer pad is placed inside the battery cell. However, the structural design of the buffer pad is unreasonable, making it difficult to solve the problem of lithium or sodium deposition caused by wrinkling of the electrode sheet. Moreover, in the later stage of the cycle of the electrode assembly, the expansion force is too large and the electrode sheet is wrinkled, resulting in serious lithium or sodium deposition problems, affecting the performance and service life of the battery cell.

[0096] Other related technologies employ elastic support plates within battery cells to address the problem of loose contact between the positive and negative electrodes and the separator during the charge and discharge cycles of the electrode assembly. However, these plates occupy a significant amount of space within the battery cell, impacting its energy density. Furthermore, the plates' poor compressibility creates the risk of a sharp increase in expansion forces later in the battery cell's lifespan.

[0097] Based on this, the present application proposes a buffer member 10 for use within a battery cell 100. The battery cell 100 includes an electrode assembly 20. The buffer member 10 includes a first surface 11 and a second surface 12 disposed opposite each other. The buffer member 10 also includes a through-channel 14 extending through the first and second surfaces 11 and 12. The buffer member 10 is compressible to buffer the expansion of the electrode assembly 20, and the through-channel 14 is used to increase the compressibility of the buffer member 10.

[0098] In the buffer member 10 of the above-described structure, the provision of the buffer member 10 can provide better support for the electrode assembly 20 when the electrode assembly 20 expands slightly, reducing electrode sheet deformation and improving the wrinkling of the electrode sheet caused by the expansion of the electrode assembly 20, thereby alleviating the problem of lithium or sodium deposition in the electrode assembly 20 during cycling and improving the performance of the battery cell 100. Furthermore, the provision of the through-channel 14 can increase the compressibility of the buffer member 10, so that when the electrode assembly 20 expands significantly, the buffer member 10 can be effectively compressed to reduce the occupied space. The buffering effect balances the expansion and accommodates the deformation of the electrode assembly 20, preventing excessive expansion force from causing lithium or sodium deposition at the interface. The electrode sheet is also less likely to deform and cause lithium or sodium deposition, effectively improving the cycling performance of the battery cell 100.

[0099] The buffer component 10 disclosed in the embodiment of the present application can be used in a battery cell 100, the battery cell 100 can be used in a battery 1000, and the battery 1000 can be used in, but not limited to, an electrical device 2000 such as a vehicle, a ship, or an aircraft. The power supply system of the electrical device 2000 composed of the battery 1000 disclosed in the present application can ensure the safety and reliability of the electrical device 2000.

[0100] For example, the power-consuming device 2000 disclosed in the embodiments of the present application may be, but is not limited to, a vehicle, a mobile phone, a tablet, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, etc. A vehicle may be a fuel vehicle, a gas vehicle, a new energy vehicle, or a rail vehicle, and a new energy vehicle may be a pure electric vehicle, a hybrid vehicle, or an extended-range vehicle, etc.; a spacecraft includes an airplane, a rocket, a space shuttle, and a spacecraft, etc.; an electric toy includes a fixed or mobile electric toy, such as a game console, an electric vehicle toy, an electric ship toy, and an electric airplane toy, etc.; an electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool, and a railway electric tool, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact drill, a concrete vibrator, and an electric planer, etc.

[0101] Hereinafter, with reference to the accompanying drawings, a buffer member 10 according to an embodiment of the first aspect of the present application and a battery cell 100 according to an embodiment of the second aspect of the present application will be described.

[0102] As shown in Figures 1-6, Figures 1-2 are schematic structural diagrams of a battery cell 100 provided in embodiments of the present application; Figures 3 and 4 are cross-sectional views of the battery cell 100 along lines AA and BB in Figure 2, respectively, provided in some embodiments of the present application; Figure 5 is a cross-sectional view of the battery cell 100 along line BB in Figure 2 provided in other embodiments of the present application; and Figure 6 is a cross-sectional view of the battery cell 100 along line BB in Figure 2 provided in still other embodiments of the present application. A buffer member 10 according to an embodiment of the present application is used within the battery cell 100. The buffer member 10 includes a first surface 11 and a second surface 12 disposed opposite each other, and includes a through-channel 14 extending through the first and second surfaces 11 and 12. The battery cell 100 includes an electrode assembly 20. The buffer member 10 is compressible to buffer expansion of the electrode assembly 20. The through-channel 14 is used to increase the compressibility of the buffer member 10.

[0103] The buffer member 10 is used inside the battery cell 100. For example, in some embodiments, the battery cell 100 may include a housing 30, an electrode assembly 20, and the buffer member 10, with both the buffer member 10 and the electrode assembly 20 disposed within the housing 30. This allows the buffer member 10 to be closer to the electrode assembly 20, thereby providing timely buffering for the expansion of the electrode assembly 20, reducing the increase in expansion force during use of the electrode assembly 20, improving the problem of uneven force distribution on the electrode assembly 20 during use, and improving the service life and reliability of the electrode assembly 20.

[0104] Among them, the buffer member 10 can be arranged between the electrode assembly 20 and the shell 30, as shown in Figures 3-4 and 6. The buffer member 10 can not only support and cushion the electrode assembly 20, but also separate the electrode assembly 20 from the shell 30, so that the electrode assembly 20 is not easily squeezed from the shell 30 after expansion.

[0105] Alternatively, the buffer member 10 can be arranged between the electrode assemblies 20. For example, as shown in Figures 5 and 6, there are multiple electrode assemblies 20 arranged along the first direction F1, and the buffer member 10 is arranged between two adjacent electrode assemblies 20. The buffer member 10 can not only support and buffer the electrode assemblies 20, but also separate the adjacent electrode assemblies 20 so that the electrode assemblies 20 are not easily squeezed against each other after expansion.

[0106] Of course, the buffer member 10 can also be partially disposed between the electrode assembly 20 and the housing 30, and partially disposed between adjacent electrode assemblies 20, as shown in FIG6 . This is also within the scope of protection of this application. It should be noted that the buffer member 10 disposed between the electrode assembly 20 and the housing 30 and the buffer member 10 disposed between adjacent electrode assemblies 20 can be different parts of the same buffer member 10, or can be independent and different buffer members 10.

[0107] The first surface 11 and the second surface 12 arranged opposite to each other refer to the surfaces of the buffer 10 located on both sides of the set direction. For example, Figures 7 to 12 are structural schematic diagrams of the buffer 10 of the first to sixth embodiments of the present application. The first surface 11 and the second surface 12 are the surfaces of the buffer 10 on both sides of the first direction F1. Of course, in other embodiments, the first surface 11 and the second surface 12 may also be the surfaces of the buffer 10 on both sides of the second direction F2 shown in Figures 7 to 12 or the surfaces on both sides of the third direction F3, wherein the first direction F1, the second direction F2 and the third direction F3 intersect with each other, for example, are perpendicular to each other.

[0108] The through-channel 14 is provided through the first surface 11 and the second surface 12, that is, end openings of the through-channel 14 are formed on the first surface 11 and the second surface 12, respectively. The extension path of the through-channel 14 from the first surface 11 to the second surface 12 is not limited. For example, the through-channel 14 can extend along a straight line as shown in Figures 7-12, or along a broken line, a curve, or the like. The shape of the end opening includes, but is not limited to, the circular, rectangular, trapezoidal, triangular, and other shapes shown in Figures 7-12.

[0109] In addition, the sidewalls of the through-channel 14 can be continuous, closed annular surfaces, as shown in Figures 8-12 , i.e., they are closed walls in any direction perpendicular to the extension path of the through-channel 14, which helps improve the stability of the buffer 10 supporting the electrode assembly 20 during the early stages of the cycle of the electrode assembly 20. Alternatively, the sidewalls of the through-channel 14 can also be open on the sides, as shown in Figure 7 , where the through-channel 14 is open on three sides at the edge of the buffer 10, making it easier to process.

[0110] The buffer member 10 is compressible, that is, it can be compressed and deformed when subjected to external force to reduce the occupied space; and when the external force is removed, it can at least partially recover the deformation, so as to provide stable support for the electrode assembly 20.

[0111] The compressibility of the buffer 10 refers to the ratio of the volume of the buffer 10 reduced when the buffer 10 is compressed to the volume of the buffer 10 in the natural state.

[0112] The through channel 14 is used to increase the compressibility of the buffer 10 , that is, compared with a buffer of the same specification and material without a through channel, the compressibility of the buffer 10 is increased, and the buffer 10 can be further compressed and the volume can be further reduced.

[0113] In some embodiments, the buffer 10 can be made of an elastically deformable material, utilizing its material properties to achieve compression, and further enhancing the compressibility by combining with the through-channel 14. For example, the buffer 10 can be made of materials including, but not limited to, polyethylene, polypropylene, polyethylene terephthalate, aerogel, foam, silicone rubber, etc. These materials have high pressure resistance, are tolerant to electrolytes, are low-cost, and are easy to manufacture and use.

[0114] In the early stage of the cycle of the electrode assembly 20, the buffer component 10 has a good supporting effect on the electrode assembly 20, which can reduce the deformation of the electrode piece, thereby improving the wrinkling of the electrode piece caused by the expansion of the electrode assembly 20, thereby alleviating the lithium or sodium precipitation problem of the electrode assembly 20 during the cycle.

[0115] As the electrode assembly 20 cycles repeatedly, the buffer 10 is compressed by the expansion of the electrode assembly 20, thereby reducing the space occupied while maintaining its support for the electrode assembly 20. Furthermore, by providing the through-channel 14 in the buffer 10, the buffer 10 can be further compressed and its volume can be further reduced, thereby reducing the space occupied by the buffer 10 within the housing 30. This allows sufficient space within the housing 30 to accommodate the deformation of the electrode assembly 20, thereby accommodating the increased expansion force of the electrode assembly 20 in the later stages of the cycle, preventing lithium or sodium deposition caused by excessive expansion force, and thus improving the cycling performance of the electrode assembly 20.

[0116] According to the buffer member 10 of the embodiment of the present application, the provision of the buffer member 10 can provide better support for the electrode assembly 20 when the electrode assembly 20 expands slightly, reduce electrode sheet deformation, and improve the electrode sheet wrinkling caused by the expansion of the electrode assembly 20, thereby alleviating the problem of lithium or sodium deposition in the electrode assembly 20 during cycling and improving the performance of the battery cell 100. Furthermore, the provision of the through-channel 14 can increase the compressibility of the buffer member 10, so that when the electrode assembly 20 expands significantly, the buffer member 10 can be effectively compressed to reduce the occupied space. The buffering effect balances the expansion and accommodates the deformation of the electrode assembly 20. The expansion force is not too great, which may cause lithium or sodium deposition at the interface, and the electrode sheet is not easily deformed, which may cause lithium or sodium deposition, thereby effectively improving the cycling performance of the battery cell 100.

[0117] In some embodiments of the present application, as shown in Figures 4 to 12, the buffer member 10 has a pressure-bearing surface 13 facing or facing away from the electrode assembly 20, and the first surface 11 and / or the second surface 12 are the pressure-bearing surfaces 13. The pressure-bearing surface 13 is the surface of the buffer member 10 that is squeezed when the electrode assembly 20 expands. The pressure-bearing surface 13 can be a surface that directly faces the electrode assembly 20 to support and bear the pressure, or a surface that faces away from the electrode assembly 20 to indirectly bear the pressure. For example, the surface of the buffer member 10 that faces the housing 30 and faces away from the electrode assembly 20, and the surface of the buffer member 10 that faces the electrode assembly 20 are both pressure-bearing surfaces 13.

[0118] At least one of the first surface 11 and the second surface 12 is a pressure-bearing surface 13, that is, a surface with an end opening through the channel 14 is formed as the pressure-bearing surface 13, so that the actual force-bearing area of ​​the pressure-bearing surface 13 is reduced and the force-bearing surface pressure per unit area is increased, thereby more effectively improving the compressibility of the buffer 10 and solving the problems of large expansion force in the later stage of the cycle and volume occupation of the buffer 10.

[0119] In some embodiments of the present application, the total opening area of ​​the end openings of the through-channel 14 formed on the same side surface is S1, and the area of ​​the corresponding surface is S2. The total opening area of ​​the end openings is the sum of the areas of all end openings. For example, if the end opening is circular, the radius of the circle is R, and n end openings of equal area are set on the same side surface, then S1 is nπR 2 The area of ​​the surface is the area of ​​the surface when no end opening is provided. For example, if the first surface 11 is a rectangle, the area of ​​the first surface 11 is the product of the length and width of the rectangle.

[0120] In addition, S1 and S2 satisfy the following ratio: S1 / S2 is greater than or equal to 5% and less than or equal to 80%. Too many through-channels 14 will affect the support effect, while too few through-channels 14 will not significantly improve the compressibility. Within the above ratio range, the number and volume of through-channels 14 are reasonable to simultaneously take into account the support effect of the buffer 10 on the electrode assembly 20 and the effect of improving the compressibility. For example, in some specific embodiments, S1 / S2 can be 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, and 80%.

[0121] In some embodiments, S1 and S2 further satisfy: S1 / S2 is greater than or equal to 20% and less than or equal to 50%, so as to further improve the supporting effect and compressibility of the buffer 10.

[0122] In some embodiments of the present application, the equivalent diameter of the end opening of the through-channel 14 is greater than or equal to 2 mm and less than or equal to 20 mm. The equivalent diameter of the end opening refers to the diameter of a circle with the same cross-sectional area as the end opening. For example, if the end opening is circular, the equivalent diameter of the end opening can be the diameter of the circle; if the end opening is a non-circular shape such as a triangle, the equivalent diameter of the end opening can be the diameter of a circle with the same area as the non-circular shape such as the triangle.

[0123] In some specific embodiments, the equivalent diameter of the end opening may be 2 mm, 5 mm, 10 mm, 15 mm, 20 mm, etc.

[0124] The equivalent diameter of the end opening ranges from 2 mm to 20 mm, and the equivalent diameter of the end opening will not be too large or too small, which effectively improves the overall structural strength of the buffer 10 and improves the structural stability to improve the supporting capacity; it is also beneficial to effectively improve the compressibility of the buffer 10, thereby better meeting the buffering needs in the later stage of the cycle.

[0125] In some embodiments, the equivalent diameter of the end opening further satisfies a value greater than or equal to 5 mm and less than or equal to 10 mm, so as to further improve the supporting capacity and compressibility of the buffer 10 .

[0126] In the embodiment of the present application, the number and arrangement of the through channels 14 can be flexibly set.

[0127] For example, in some embodiments, as shown in Figures 7-12 , there are multiple through-channels 14, that is, there are two or more through-channels 14. Given a given total volume of through-channels 14, the cross-sectional area of ​​each through-channel 14 is smaller, improving the compressibility while also helping to maintain the structural strength and support capacity of the cushioning element 10. Furthermore, multiple through-channels 14 provide a relatively more uniform distribution of the pore structure across the cushioning element 10, which helps improve compressibility uniformity and support stability across different regions of the cushioning element 10.

[0128] In some embodiments, at least two through-channels 14 intersect and communicate with each other. For example, of the two intersecting through-channels 14, one through-channel 14 extends along the first direction F1, and the other through-channel 14 extends along the second direction F2. The two through-channels 14 pass through the same area on the cushioning member 10 to communicate with each other. This intersecting arrangement further improves the compressibility of the cushioning member 10.

[0129] It should be noted that in the above embodiments, among the multiple through channels 14, some of the through channels 14 may be separated from and not connected to other through channels 14, or any through channel 14 may intersect and be connected to at least one other through channel 14, which are all within the scope of protection of the present application.

[0130] In other embodiments, multiple through-channels 14 are spaced apart. In other words, no two through-channels 14 are connected to each other. This not only improves the uniformity of the distribution of through-channels 14 on the cushioning member 10, thereby enhancing the support effect of the cushioning member 10, but also reduces the difficulty of machining the through-channels 14.

[0131] For example, as shown in Figure 7, multiple through-channels 14 extend along the first direction F1 to penetrate the cushioning member 10. These through-channels 14 are arranged in an array perpendicular to the first direction F1, spaced apart from each other. This array arrangement provides a more uniform distribution of the through-channels 14, improving support stability and compressibility. For example, the through-channels 14 can be arranged in multiple rows along the second direction F2, with each row including multiple through-channels 14 arranged along the third direction F3.

[0132] Of course, in the embodiment including multiple through-channels 14 , the extension directions of the multiple through-channels 14 may be the same or different, as long as the requirement that the multiple through-channels 14 are not interconnected is met.

[0133] According to some embodiments of the present application, please refer to Figures 13-15. Figure 13 is a schematic diagram of the structure of a buffer member 10 and an electrode assembly 20 according to the seventh embodiment of the present application; Figure 14 is a schematic diagram of the structure of a buffer member 10 according to the seventh embodiment of the present application; and Figure 15 is a schematic diagram of the structure of a buffer member 10 according to the eighth embodiment of the present application. The buffer member 10 includes a first buffer region 15 and a second buffer region 16. For ease of understanding, the first buffer region 15 and the second buffer region 16 are marked and divided by a dotted box in Figures 14-15. It should be understood that the dotted box does not represent the structure of the buffer member 10.

[0134] At the same pressure, the compressibility of the second buffer region 16 is greater than that of the first buffer region 15. In other words, at the same pressure, the volume of the second buffer region 16 decreases more than that of the first buffer region. Regarding the electrode assembly 20 of the battery cell 100, different regions of the electrode assembly 20 expand differently during cycling. For example, the center expands more than the edges; another example is that regions of the electrode sheet with a thicker active material coating expand more than regions with a thinner active material coating.

[0135] Therefore, when the buffer member 10 is used for the battery cell 100, the first buffer area 15 and the second buffer area 16 can correspond to different areas of the electrode assembly 20 respectively, so as to balance the expansion force differences in different areas of the battery cell 100 according to the expansion conditions of different areas of the electrode assembly 20, which is beneficial to improving the interface lithium or sodium precipitation problem caused by uneven expansion force distribution and improving the long-term cycle stability of the battery cell 100.

[0136] In some embodiments of the present application, please refer to Figures 13 to 16. Figure 16 is a schematic diagram of a partial structure of the electrode assembly 20 provided in an embodiment of the present application. The buffer member 10 is provided on the side of the electrode assembly 20 along the first direction F1. The electrode assembly 20 includes an electrode body 21 and a pole ear 22 provided at the end of the electrode body 21. The electrode body 21 includes a first electrode region 211 and a second electrode region 212. The number of pole piece layers of the first electrode region 211 along the first direction F1 is less than the number of pole piece layers of the second electrode region 212 along the first direction F1. The buffer member 10 has a first buffer region 15 and a second buffer region 16. The first buffer region 15 is provided corresponding to the first electrode region 211, and the second buffer region 16 is provided corresponding to the second electrode region 212. The compressibility of the first buffer region 15 is less than the compressibility of the second buffer region 16.

[0137] The electrode body 21 includes electrode plates, which expand during the cycling of the electrode assembly 20. Furthermore, the more electrode plates there are, the greater the expansion. The number of electrode plates in the first electrode region 211 along the first direction F1 is smaller than the number of electrode plates in the second electrode region 212 along the first direction F1. Therefore, the expansion of the first electrode region 211 in the first direction F1 is smaller than the expansion of the second electrode region 212 in the first direction F1.

[0138] By placing the first buffer region 15 with a small compressibility opposite to the first electrode region 211 with a small expansion, and the second buffer region 16 with a large compressibility opposite to the second electrode region 212 with a large expansion, the first electrode region 211 squeezes the first buffer region 15, and the second electrode region 212 squeezes the second buffer region 16, thereby effectively balancing the expansion force difference between the first electrode region 211 and the second electrode region 212, improving the problem of interfacial lithium or sodium deposition caused by uneven expansion force of the battery cell 100, balancing the thickness difference between the first electrode region 211 and the second electrode region 212, and improving the long-term cycle stability of the battery cell 100.

[0139] In some specific embodiments, as shown in FIG16 , the electrode assembly 20 includes a positive electrode sheet 23, a negative electrode sheet 24, and a separator 25 disposed between the positive electrode sheet 23 and the negative electrode sheet 24. The first electrode region 211 includes the positive electrode sheet 23, the separator 25, and the negative electrode sheet 24 in a stacked arrangement. The second electrode region 212 includes the negative electrode sheet 24 and the separator 25 in a stacked arrangement, or the second electrode region 212 includes the negative electrode sheet 24.

[0140] When the positive electrode sheet 23, the negative electrode sheet 24 and the separator 25 are stacked and wound to obtain the electrode assembly 20, the area of ​​the negative electrode sheet 24 can be made larger than the area of ​​the positive electrode sheet 23, so that the negative electrode sheet 24 is partially staggered with the positive electrode sheet 23, so that the staggered portion is formed into the second electrode region 212, and the non-staggered portion (i.e., the overlapping portion) is formed into the first electrode region 211. The larger size of the negative electrode sheet 24 is conducive to the negative electrode sheet 24 fully receiving the lithium ions provided by the positive electrode sheet 23, thereby giving full play to the electrical properties of the positive electrode material and improving the lithium plating problem. Among them, the staggered portion expands less during the cycle, and the non-staggered portion expands more during the cycle. By having the first buffer region 15 opposite to the first electrode region 211 and the second buffer region 16 opposite to the second electrode region 212, the thickness difference between the two regions can be balanced, further improving the lithium plating problem and improving the cycle stability.

[0141] The difference in compressibility between the first buffer region 15 and the second buffer region 16 can be flexibly adjusted by adjusting the number and location of the through-channels 14 .

[0142] For example, in some embodiments, as shown in Figures 13 and 14 , through-channels 14 are provided in the second cushioning region 16. In other words, no through-channels 14 are provided in the first cushioning region 15. This allows the compressibility of the second cushioning region 16 to be greater than that of the first cushioning region 15, balancing the differences in expansion forces between the different regions while also reducing the number of through-channels 14 and improving the support capacity of the cushioning element 10.

[0143] In other embodiments, as shown in FIG. 15 , the total volume of the through-channel 14 in the first buffer region 15 is smaller than the total volume of the through-channel 14 in the second buffer region 16 .

[0144] The total volume of a through-channel 14 refers to the sum of the volumes of all through-channels 14 in that region. In embodiments where multiple through-channels 14 on the buffer member 10 are of equal structure and size, the number of through-channels 14 in the first buffer region 15 can be smaller than the number of through-channels 14 in the second buffer region 16 to achieve a difference in total volume, and thus a difference in compressibility. This allows the compressibility of the second buffer region 16 to be greater than that of the first buffer region 15, balancing the differences in expansion forces between regions while also enabling the first buffer region 15 to better accommodate expansion of the electrode assembly 20 during later cycles.

[0145] In some embodiments, as shown in Figure 15, the equivalent aperture of the end opening of the through-channel 14 is d. The equivalent aperture of the end opening refers to the diameter of a circle having the same area as the end opening.

[0146] In the first buffer region 15, the spacing W1 between the end openings of two adjacent through-channels 14 is greater than or equal to 2d and less than or equal to 4d. In the second buffer region 16, the spacing W2 between the end openings of two adjacent through-channels 14 is greater than or equal to d / 3 and less than or equal to 2d.

[0147] Within this spacing range, the through-channels 14 of the second buffer region 16 are denser than those of the first buffer region 15, so that the compressibility of the second buffer region 16 is greater than that of the first buffer region 15. Furthermore, the end openings of each buffer region are not arranged too densely, thereby weakening the structural strength of the corresponding buffer region, thereby ensuring the support stability of the corresponding buffer region; and the end openings are not arranged too sparsely, thereby reducing the compressibility and failing to meet the requirements of the later stages of the cycle.

[0148] In some specific embodiments, the minimum distance between the end opening of the first buffer area 15 and the edge of the buffer 10 is d / 2, so that the edge area of ​​the buffer 10 has good structural strength and support stability, and the edge area can have a certain compressibility.

[0149] According to some embodiments of the present application, the compressibility of the first buffer region 15 at a pressure of 0.5 MPa is not less than 40%, the compressibility at a pressure of 0.8 MPa is not less than 60%, and the compressibility at a pressure of 1 MPa is not less than 85%. The compressibility of the second buffer region 16 at a pressure of 0.5 MPa is not less than 20%, the compressibility at a pressure of 0.8 MPa is not less than 30%, and the compressibility at a pressure of 1 MPa is not less than 50%.

[0150] Among them, the pressure of 0.5Mpa, the pressure of 0.8Mpa and the pressure of 1Mpa generally correspond to the pressures to which the buffer 10 is subjected in the early, middle and late stages of the cycle of the electrode assembly 20. The above pressures come from the expansion force of the electrode assembly 20 and the gas pressure inside the shell 30. Of course, the above values ​​are not limitations on the actual pressures to which the buffer 10 is subjected in the early, middle and late stages of the cycle of the electrode assembly 20. Instead, they indicate that when the compressibility of the first buffer region 15 and the second buffer region 16 meets the above conditions under the above pressures, they can meet the compressibility requirements for the early, middle and late stages of the cycle of the electrode assembly 20. In fact, different cycle times and different specific positions on the buffer 10 will result in different pressures. For example, in the early stages of the cycle, the actual pressure to which the first buffer region 15 is subjected can vary within a certain range of 0.5Mpa.

[0151] By ensuring that the compressibility of the first buffer region 15 and the second buffer region 16 satisfies the above-mentioned ratio range under the above-mentioned different pressures, the first buffer region 15 and the second buffer region 16 can effectively balance the expansion force differences in different regions of the electrode assembly 20 throughout the entire cycle, thereby improving the long-term cycle stability of the battery cell 100.

[0152] The number and relative positions of the first buffer regions 15 and the second buffer regions 16 can be flexibly set according to the actual situation of the electrode assembly 20. In some embodiments, the through channel 14 penetrates the buffer member 10 along the first direction F1, and there are two first buffer regions 15, and the two first buffer regions 15 are respectively located on both sides of the second buffer region 16 along the second direction F2, and the first direction F1 intersects the second direction F2.

[0153] For example, as shown in FIG. 14 and FIG. 15 , the through channel 14 penetrates the buffer member 10 along the thickness direction of the buffer member 10 , ie, the left-right direction. The first buffer region 15 is provided on both sides of the upper and lower sides of the second buffer region 16 .

[0154] The above-mentioned arrangement of the first buffer area 15 and the second buffer area 16 can meet the thickness difference in the second direction F2 where the expansion force at both ends is small and the expansion force in the middle is large. The corresponding electrode assembly 20 can adopt a structure in the second direction F2 where the middle part is the second electrode area 212 and the two sides are the first electrode areas 211, so that both ends of the electrode assembly 20 can fully exert their electrical performance.

[0155] In some embodiments where there are two first buffer regions 15 and the two first buffer regions 15 are respectively located on both sides of the second buffer region 16 along the second direction F2, as shown in Figures 13 and 14, in the second direction F2, the size of the first buffer region 15 is H1, the size of the second buffer region 16 is H2, and the size of the electrode body 21 is H3.

[0156] In an embodiment where the first buffer region 15 does not have end openings, as shown in Figure 13 , the dimension H1 of the first buffer region 15 is the minimum distance between the end openings of the second buffer region 16 and the edge of the buffer member 10. The dimension H2 of the second buffer region 16 is the distance along the second direction F2 between the two end openings at both ends of the second buffer region 16, which are separated from each other. In an embodiment where the first buffer region 15 has end openings, as shown in Figure 14 , the boundary between the first buffer region 15 and the second buffer region 16 passes through the midpoint between the two closest end openings of the first buffer region 15 and the second buffer region 16.

[0157] Among them, H3-(H2+2H1) is greater than or equal to -2.5mm and less than or equal to 14.5mm, and H1 is greater than or equal to 3.5mm and less than or equal to 5.5mm. If the size of the buffer 10 along the second direction F2 is too large, the buffer 10 will exceed the edge size of the electrode body 21 too much, which is costly and takes up space, and is likely to interfere with other structures. If the size of the buffer 10 along the second direction F2 is too small, the electrode body 21 will exceed the edge size of the buffer 10 too much, and the buffer 10 will not be able to fully support the easily expanded area of ​​the electrode body 21. If the size of the first buffer area 15 along the second direction F2 is too large, it will lead to poor expansion force balancing effect in the central area of ​​the electrode assembly 20. If the size of the first buffer area 15 along the second direction F2 is too small, the overall strength of the buffer 10 will be weak.

[0158] Within the above-mentioned value range, the buffer component 10 can provide stable support to the areas of the electrode body 21 that are prone to expansion, and provide more precise support and buffering for areas with larger and smaller expansion forces, and is conducive to reducing the volume of the buffer component 10, reducing occupied space and cost.

[0159] For example, in some specific embodiments, H3-(H2+2H1) can be -2 mm, -1 mm, 0 mm, 1 mm, 3 mm, 5 mm, 8 mm, 10 mm, 12 mm, 14 mm, etc. H1 can be 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, etc.

[0160] In some specific embodiments, H3-(H2+2H1) is greater than or equal to 6.5 mm and less than or equal to 10 mm, so as to further improve the overall support and buffering effect of the buffer member 10 on the electrode body 21 and better reduce the space occupied by the buffer member 10.

[0161] In some embodiments of the present application, as shown in Figures 13-15 , a buffer member 10 is disposed on a side surface of an electrode assembly 20 along a first direction F1. The electrode assembly 20 includes an electrode body 21 and a tab 22 disposed at the end of the electrode body 21. The electrode body 21 includes a third electrode region and a fourth electrode region. The thickness of the electrode sheet of the electrode assembly 20 in the third electrode region is less than that in the fourth electrode region. The buffer member 10 has a third buffer region 17 and a fourth buffer region 18. The third buffer region 17 is disposed corresponding to the third electrode region, and the fourth buffer region 18 is disposed corresponding to the fourth electrode region. The compressibility of the third buffer region 17 is less than that of the fourth buffer region 18.

[0162] The electrode body 21 includes a pole piece, which expands during cycling of the electrode assembly 20. Furthermore, the thicker the pole piece, the greater the expansion. The thickness of the third electrode region along the first direction F1 is less than the thickness of the fourth buffer region 18 along the first direction F1. Therefore, the expansion of the third electrode region in the first direction F1 is less than the expansion of the fourth buffer region 18 in the first direction F1.

[0163] By placing the third buffer region 17 with a small compressibility opposite to the third electrode region with a smaller expansion, and the fourth buffer region 18 with a large compressibility opposite to the fourth electrode region with a larger expansion, the third electrode region squeezes the third buffer region 17, and the fourth electrode region squeezes the fourth buffer region 18, thereby effectively balancing the expansion force difference corresponding to the third electrode region and the fourth electrode region, improving the problem of interfacial lithium or sodium deposition caused by uneven expansion force of the battery cell 100, balancing the thickness difference between the third electrode region and the fourth electrode region, and improving the long-term cycle stability of the battery cell 100.

[0164] Among them, the difference in compressibility between the third buffer area 17 and the fourth buffer area 18 can be flexibly adjusted by adjusting the number and setting position of the through channels 14. The adjustment method is similar to that of the third buffer area 17 and the fourth buffer area 18, and will not be repeated here.

[0165] In some specific embodiments, the electrode sheet includes a current collector and an active material layer coated on the surface of the current collector. For example, the positive electrode sheet 23 includes a positive current collector and a positive active material layer, and the negative electrode sheet 24 includes a negative current collector and a negative active material layer. The thickness of the active material layer in the third electrode region of the electrode sheet is less than the thickness of the active material layer in the fourth electrode region. During the electrode sheet rolling process, the active material layer of the electrode sheet spreads from the center to the ends in the width direction and accumulates at the ends of the electrode sheet. The thickness of the active material layer in the third electrode region is less than that in the fourth electrode region, providing a compensating position for the active material layer that accumulates from the center to the ends. This ensures that the thickness of the active material layer at the ends of the electrode sheet after rolling does not exceed the thickness in the center, thereby reducing the amount of active material layer accumulation at the ends. Furthermore, during the rolling process, the portion of the electrode sheet located in the third electrode region is subjected to less pressure, thereby reducing the risk of peeling or shedding of the active material in the third electrode region and the possibility of cracks forming at the interface between the portions of the electrode sheet located in the third and fourth electrode regions.

[0166] It should be noted that the electrode assembly 20 can be such that the thickness of the positive active material layer of the positive electrode sheet 23 located in the third electrode region is less than the thickness of the positive active material layer of the positive electrode sheet 23 located in the fourth electrode region, and the thickness of the negative active material layer of the negative electrode sheet 24 located in the third electrode region is equal to the thickness of the negative active material layer of the negative electrode sheet 24 located in the fourth electrode region; it can also be such that the thickness of the positive active material layer of the positive electrode sheet 23 located in the third electrode region is equal to the thickness of the positive active material layer of the positive electrode sheet 23 located in the fourth electrode region, and the thickness of the negative active material layer of the negative electrode sheet 24 located in the third electrode region is effective to the thickness of the negative active material layer of the negative electrode sheet 24 located in the fourth electrode region; it can also be such that the thickness of the positive active material layer of the positive electrode sheet 23 located in the third electrode region is less than the thickness of the positive active material layer of the positive electrode sheet 23 located in the fourth electrode region, and the thickness of the negative active material layer of the negative electrode sheet 24 located in the third electrode region is less than the thickness of the negative active material layer of the negative electrode sheet 24 located in the fourth electrode region.

[0167] The number and relative positions of the third buffer regions 17 and the fourth buffer regions 18 can be flexibly set according to the actual situation of the electrode assembly 20. In some embodiments, there are two third buffer regions 17, and the two third buffer regions 17 are respectively located on both sides of the fourth buffer region 18 along the second direction F2, and the first direction F1 intersects the second direction F2.

[0168] For example, as shown in FIG. 14 and FIG. 15 , the through channel 14 penetrates the buffer member 10 along the thickness direction of the buffer member 10 , ie, the left-right direction. The third buffer region 17 is provided on both sides of the upper and lower sides of the fourth buffer region 18 .

[0169] The above-mentioned arrangement of the third buffer area 17 and the fourth buffer area 18 can meet the thickness difference in the second direction F2 where the expansion force at both ends is small and the expansion force in the middle is large. The corresponding electrode assembly 20 can adopt a structure in the second direction F2 where the middle part is the fourth electrode area and the two sides are the third electrode areas, so that both ends of the electrode assembly 20 can fully exert their electrical performance.

[0170] In the second direction F2, the size of the third buffer area 17 is H4, the size of the fourth buffer area 18 is H5, and the size of the electrode body 21 is H3. Among them, H3-(H5+2H4) is greater than or equal to -2.5mm and less than or equal to 20mm, and H4 is greater than or equal to 1mm and less than or equal to 10mm. If the size of the buffer 10 along the second direction F2 is too large, the buffer 10 will exceed the edge size of the electrode body 21 too much, which is costly and takes up space, and is likely to interfere with other structures. If the size of the buffer 10 along the second direction F2 is too small, the electrode body 21 will exceed the edge size of the buffer 10 too much, and the buffer 10 will not be able to fully support the easily expanded area of ​​the electrode body 21. If the size of the third buffer area 17 along the second direction F2 is too large, the expansion force balance effect on the central area of ​​the electrode assembly 20 will be poor, and the active material of the electrode assembly 20 will have less impact on the electrical performance; if the size of the third buffer area 17 along the second direction F2 is too small, the overall strength of the buffer component 10 will be weak, and the active material layer will easily accumulate excessively at both ends during the rolling process of the electrode assembly 20.

[0171] Within the above range, the buffer 10 can provide stable support to areas of the electrode body 21 prone to expansion, and more precisely support and cushion areas with greater and lesser expansion forces. This also helps reduce the volume of the buffer 10, reducing space and cost. This also maintains the electrical performance of the electrode assembly 20 and reduces active material accumulation during rolling.

[0172] For example, in some specific embodiments, H3-(H5+2H4) can be -2mm, -1mm, 0mm, 1mm, 3mm, 5mm, 8mm, 10mm, 15mm, 18mm, 20mm, etc. H4 can be 1mm, 3mm, 5mm, 7mm, 10mm, etc.

[0173] In some specific embodiments, H3-(H5+2H4) is greater than or equal to 6.5 mm and less than or equal to 13 mm, so as to further improve the overall support and buffering effect of the buffer 10 on the electrode body 21 and at the same time reduce the space occupied by the buffer 10.

[0174] In the embodiment of the present application, the arrangement position of the buffer member 10 relative to the electrode assembly 20 can be flexibly arranged according to the structure of the electrode assembly 20 .

[0175] For example, according to some embodiments of the present application, the electrode assembly 20 includes a plurality of pole pieces arranged in a winding manner, and the outer peripheral surface of the electrode assembly 20 includes a straight portion 26 and a bend portion 27 connected to the end of the straight portion 26, and at least one of the straight portion 26 and the bend portion 27 is arranged opposite to the buffer member 10.

[0176] Multiple electrode sheets, namely the positive electrode sheet 23 and the negative electrode sheet 24, are stacked and wound around a predetermined axis to form the electrode assembly 20. The straight portion 26 refers to the portion of the electrode sheet that extends along a plane during winding; the curved portion 27 refers to the portion of the electrode sheet that extends along an arc during winding. For example, as shown in Figure 3, the left and right surfaces of the electrode assembly 20 are formed as straight portions 26, and the left and right ends of the front and rear surfaces are formed as curved portions 27. Alternatively, the front and rear surfaces can be formed as a whole as curved portions 27.

[0177] The straight portion 26 is disposed opposite the buffer member 10, allowing the buffer member 10 to provide a buffering effect on the area of ​​the electrode assembly 20 corresponding to the straight portion 26. The bent portion 27 is disposed opposite the buffer member 10, so that the area of ​​the buffer member 10 facing the bent portion 27 is generally formed into an arc. This allows the buffer member 10 to buffer the expansion force of the bent portion 27, thereby reducing the risk of bridge breakage and lithium deposition in the electrode assembly 20.

[0178] According to other embodiments of the present application, the electrode assembly 20 includes a plurality of positive electrode sheets 23 and a plurality of negative electrode sheets 24 stacked along a first direction F1. That is, the positive electrode sheets 23 and the negative electrode sheets 24 extend along a plane perpendicular to the first direction F1, and all the positive electrode sheets 23 and all the negative electrode sheets 24 of the electrode assembly 20 are stacked. The electrode assembly 20 of the above structure will expand in the first direction F1 during use. Therefore, the buffer member 10 is disposed opposite to at least one surface of the electrode assembly 20 along the first direction F1. This allows the buffer member 10 to effectively cushion and support the electrode assembly 20, and the buffer member 10 requires a small area, resulting in low cost.

[0179] In some embodiments, as shown in FIG13 , the end opening of the through-channel 14 forms a pressure-bearing surface 13 of the buffer 10 , which is the surface of the buffer 10 facing toward or away from the electrode assembly 20 . The electrode stacking direction of the electrode assembly 20 in the area opposite the pressure-bearing surface 13 is perpendicular to the pressure-bearing surface 13 .

[0180] Here, the area of ​​the electrode assembly 20 opposite to the pressure-bearing surface 13, for example, in the wound electrode assembly 20, refers to the area corresponding to the straight portion 26, and the stacking direction of the positive electrode sheet 23 and the negative electrode sheet 24 is aligned with the pressure-bearing surface 13; for another example, in the laminated electrode assembly 20, multiple positive electrode sheets 23 and multiple negative electrode sheets 24 are stacked along the first direction F1, and the pressure-bearing surface 13 is perpendicular to the first direction F1.

[0181] During use, the electrode is more likely to expand along the stacking direction. The stacking direction of the electrode in the area opposite to the pressure-bearing surface 13 is perpendicular to the pressure-bearing surface 13, so that the pressure-bearing surface 13 can more fully provide cushioning and support to the electrode, thereby improving the effect of reducing electrode wrinkling.

[0182] In some embodiments, as shown in FIG. 3 to FIG. 7 , the buffer member 10 and the electrode assembly 20 are arranged along the first direction F1 , and the surfaces of the electrode assembly 20 on both sides along the first direction F1 are the surfaces with the largest areas.

[0183] For electrode assemblies 20, larger areas are more susceptible to expansion and deformation. By placing the buffer 10 opposite the largest surface of the electrode assembly 20, the buffer 10 can provide support and compress in areas of the electrode assembly 20 more prone to expansion and deformation, effectively reducing expansion forces. This also helps reduce the amount of buffer 10 used, lowering costs, reducing space requirements, and increasing energy density.

[0184] Of course, according to actual needs, the buffer member 10 may also be provided corresponding to the non-largest surface of the electrode assembly 20 , for example, the buffer members 10 may be provided correspondingly on both sides along the third direction F3 .

[0185] The following is further described with reference to some embodiments and comparative examples.

[0186] Cycle retention rate test method:

[0187] The cycle retention rate test is conducted using two steel or aluminum plate clamps with a clamp force of 3000N. Sensors are used to monitor the large-area expansion force. The first charge and discharge are performed at a constant temperature of 25°C. Constant current and constant voltage charging (charging to a current of 0.05C) is performed at a charging current of 1.0C (the current value that completely discharges the theoretical capacity within 1 hour) until the upper voltage reaches 4.25V. After standing for 5 minutes, constant current discharge is performed at a discharge current of 1.0C until the final voltage reaches 2.8V. The discharge capacity of the first cycle is recorded. Continued charge and discharge cycles are then performed. The capacity retention rate of the nth cycle = (discharge capacity of the nth cycle / discharge capacity of the first cycle) × 100.

[0188] Identification of wrinkles on the first circle interface:

[0189] After assembly, filling, and high-temperature stabilization, the battery cell 100 undergoes a formation process at a constant temperature of 45°C. Constant-current charging is performed at a charging current of 0.1cc (the current required to completely discharge the theoretical capacity within one hour) until the voltage reaches 3.4V. This is followed by constant-current charging at a charging current of 0.33cc to 4.2V. Constant-voltage charging continues until the current reaches 0.05cc, at which point the battery 1000 is fully charged. After stabilizing the fully charged battery cell 100 for 5 minutes, it is disassembled and the wrinkles at the anode interface are observed.

[0190] Compressibility test method:

[0191] Take a sample with a size of 46*50mm and perform a compression test at 0.5mm / min. The thickness change is recorded in real time until the pressure record value reaches 1Mpa, and the compressibility change is obtained.

[0192] Example 1:

[0193] As shown in Figure 5, the battery cell 100 includes a housing 30, two electrode assemblies 20, and a buffer 10, which is positioned between the two electrode assemblies 20. The area of ​​the end opening on the same side surface of the buffer 10 accounts for 20%, and the equivalent diameter of the end opening is 8mm. The compressibility is 5% at 0.3Mpa (strong initial support effect) and 85% at 1Mpa (minimizing space occupation in the later stage). The rated capacity of the battery cell 100 is 100Ah.

[0194] Example 2:

[0195] Example 2 differs from Example 1 in that the area of ​​the end opening on the same side surface of the buffer 10 accounts for 7%, and the equivalent diameter of the end opening is 4 mm. The compressibility is 5% at 0.3 MPa and 60% at 1 MPa (which does not affect the initial support effect, but increases the residual thickness later).

[0196] Example 3:

[0197] Example 3 differs from Example 1 in that the area of ​​the end opening on the same side surface of the buffer 10 accounts for 35%, and the equivalent diameter of the end opening is 15 mm. The compressibility is 40% at 0.3 MPa (poor or even no support effect in the early stage), and 95% at 1 MPa.

[0198] Comparative Example 1:

[0199] The difference between Comparative Example 1 and Example 1 is that the buffer member is not provided with a through channel. The compressibility is 5% at 0.3 MPa (strong early support effect), and 50% at 1 MPa.

[0200] First-cycle interface wrinkling identification and cycle retention tests were performed on Examples 1 to 3 and Comparative Example 1, and expansion force data was recorded in real time until the capacity decayed to 90% SOH. The test results are shown in Table 1.

[0201] Table 1

[0202] From the comparison of the test results in Table 1, it can be seen that the provision of the buffer 10 and the provision of the through channel 14 on the buffer 10 can ensure the support effect of the buffer 10 in the early stage, improve the compressibility of the buffer 10, thereby reducing the occupied space of the buffer 10 in the later stage of the cycle, improving the interface wrinkling problem, and at the same time improving the cycle retention rate and improving the long-term cycle stability of the battery cell 100.

[0203] Referring to FIG. 17 , a battery 1000 according to an embodiment of the third aspect of the present application includes a battery cell 100 according to an embodiment of the second aspect of the present application. Thus, by employing the aforementioned battery cell 100, the buffer member 10 provides better support for the electrode assembly 20 when the electrode assembly 20 expands slightly, reducing electrode sheet deformation and improving electrode sheet wrinkling caused by electrode assembly 20 expansion. This alleviates the problem of lithium or sodium deposition in the electrode assembly 20 during cycling, thereby improving the performance of the battery cell 100. Furthermore, the provision of the through-channel 14 increases the compressibility of the buffer member 10, enabling it to be effectively compressed to reduce occupied space when the electrode assembly 20 expands significantly. The buffering effect balances expansion and accommodates deformation of the electrode assembly 20. Excessive expansion force is less likely to cause interfacial lithium or sodium deposition, and the electrode sheet is less likely to deform and cause lithium or sodium deposition, effectively improving the cycling performance of the battery cell 100.

[0204] According to an embodiment of the fourth aspect of the present application, an electrical device 2000 includes a battery 1000 according to the above-described embodiment of the present application, and the battery 1000 is used to provide electrical energy to the electrical device 2000. Thus, by adopting the above-described battery 1000, the buffer member 10 is advantageously used to provide better support for the electrode assembly 20 when the electrode assembly 20 expands slightly, reducing electrode sheet deformation and improving electrode sheet wrinkling caused by electrode assembly 20 expansion, thereby alleviating lithium or sodium deposition problems in the electrode assembly 20 during cycling and improving the performance of the battery cell 100. Furthermore, by providing the through-channel 14, the compressibility of the buffer member 10 is increased, so that when the electrode assembly 20 expands significantly, the buffer member 10 can be effectively compressed to reduce the occupied space. The buffering effect balances the expansion and accommodates the deformation of the electrode assembly 20. Excessive expansion force is unlikely to cause interfacial lithium or sodium deposition, and the electrode sheet is unlikely to deform and cause lithium or sodium deposition, effectively improving the cycling performance of the battery cell 100.

[0205] Optionally, as shown in FIG18 , when battery 1000 is used in a vehicle, it can be located at the bottom, front, or rear of the vehicle. Battery 1000 can be used to power the vehicle, for example, as an operating power source for the vehicle. The vehicle can also include a controller and a motor, with the controller controlling battery 1000 to power the motor, for example, to meet the vehicle's power requirements for starting, navigation, and driving.

[0206] 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.

[0207] 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 buffer member used inside a battery cell, wherein the battery cell includes an electrode assembly, wherein: The buffer member comprises: A first surface and a second surface disposed opposite to each other; a through channel, disposed through the first surface and the second surface; The buffer member is compressible to buffer the expansion of the electrode assembly, and the through channel is used to increase the compressibility of the buffer member.

2. The buffer member according to claim 1, wherein: The buffer component has a pressure-bearing surface facing toward or facing away from the electrode assembly, and the first surface and / or the second surface is the pressure-bearing surface.

3. The buffer member according to claim 1 or 2, wherein: The total opening area of ​​the end openings of the through channels formed on the surface on the same side is S1, and the area of ​​the corresponding surface is S2, and S1 and S2 satisfy: S1 / S2 is greater than or equal to 5% and less than or equal to 80%.

4. The buffer member according to claim 3, wherein: The S1 and the S2 further satisfy: S1 / S2 is greater than or equal to 20% and less than or equal to 50%.

5. The buffer according to any one of claims 1 to 4, wherein: The equivalent diameter of the end opening of the through-channel is greater than or equal to 2 mm and less than or equal to 20 mm.

6. The buffer member according to claim 5, wherein: The equivalent diameter of the end opening is greater than or equal to 5 mm and less than or equal to 10 mm.

7. The buffer according to any one of claims 1 to 6, wherein: There are multiple through channels, wherein at least two of the through channels cross and communicate with each other.

8. The buffer according to any one of claims 1 to 6, wherein: There are multiple through channels, and the multiple through channels are arranged at intervals.

9. The buffer member according to claim 8, wherein: The plurality of through channels all extend along a first direction, and the plurality of through channels are arranged in an array perpendicular to the first direction.

10. The buffer member according to any one of claims 1 to 9, wherein: The buffer member includes a first buffer region and a second buffer region, and the compressibility of the second buffer region is greater than the compressibility of the first buffer region under the same pressure.

11. The buffer member according to claim 10, wherein: The through-channel is provided in the second buffer region, or the total volume of the through-channel in the first buffer region is smaller than the total volume of the through-channel in the second buffer region.

12. The buffer member according to claim 11, wherein: The equivalent aperture of the end opening of the through-channel is d. In the first buffer region, the spacing between two adjacent end openings of the through-channel is greater than or equal to 2d and less than or equal to 4d. In the second buffer region, the spacing between two adjacent end openings of the through-channel is greater than or equal to d / 3 and less than or equal to 2d.

13. The buffer member according to any one of claims 10 to 12, wherein: The compressibility of the first buffer region under a pressure of 0.5 MPa is not less than 40%, the compressibility under a pressure of 0.8 MPa is not less than 60%, and the compressibility under a pressure of 1 MPa is not less than 85%; The compressibility of the second buffer region under a pressure of 0.5 MPa is not less than 20%, the compressibility under a pressure of 0.8 MPa is not less than 30%, and the compressibility under a pressure of 1 MPa is not less than 50%.

14. The buffer member according to any one of claims 10 to 13, wherein: The through channel penetrates the buffer member along a first direction. There are two first buffer regions, and the two first buffer regions are respectively located on both sides of the second buffer region along a second direction. The first direction intersects with the second direction.

15. A battery cell, wherein: The invention comprises a shell, an electrode assembly and a buffer as claimed in any one of claims 1 to 14, wherein the buffer and the electrode assembly are both arranged in the shell.

16. The battery cell according to claim 15, wherein: The electrode assembly comprises a plurality of electrode sheets arranged in a winding manner, and the outer peripheral surface of the electrode assembly comprises a straight portion and a bend portion connected to the end of the straight portion, and at least one of the straight portion and the bend portion is arranged opposite to the buffer; or, The electrode assembly includes a plurality of positive electrode sheets and a plurality of negative electrode sheets stacked along a first direction, and the buffer is disposed opposite to a surface of at least one side of the electrode assembly along the first direction.

17. The battery cell according to claim 15 or 16, wherein: The electrode assemblies are multiple and arranged along a first direction, the buffer is arranged between two adjacent electrode assemblies, and / or the buffer is arranged between the electrode assembly and the shell.

18. The battery cell according to any one of claims 15 to 17, wherein: The end opening of the through channel is formed on the pressure-bearing surface of the buffer component, and the stacking direction of the pole pieces in the area where the electrode assembly faces the pressure-bearing surface is perpendicular to the pressure-bearing surface.

19. The battery cell according to any one of claims 15 to 18, wherein: The buffer component and the electrode assembly are arranged along a first direction, and surfaces of the electrode assembly on both sides along the first direction are surfaces with the largest areas.

20. The battery cell according to any one of claims 15 to 19, wherein: The buffer member is arranged on the side of the electrode assembly along the first direction, the electrode assembly includes an electrode body and a pole ear arranged at the end of the electrode body, the electrode body includes a first electrode area and a second electrode area, the number of pole plate layers of the first electrode area along the first direction is less than the number of pole plate layers of the second electrode area along the first direction, the buffer member has a first buffer area and a second buffer area, the first buffer area is arranged corresponding to the first electrode area, the second buffer area is arranged corresponding to the second electrode area, and the compressibility of the first buffer area is less than the compressibility of the second buffer area.

21. The battery cell according to claim 20, wherein: There are two first buffer regions, and the two first buffer regions are respectively located on both sides of the second buffer region along a second direction, and the first direction intersects with the second direction. In the second direction, the size of the first buffer area is H1, the size of the second buffer area is H2, and the size of the electrode body is H3, wherein H3-(H2+2H1) is greater than or equal to -2.5 mm and less than or equal to 14.5 mm, and H1 is greater than or equal to 3.5 mm and less than or equal to 5.5 mm.

22. The battery cell according to claim 21, wherein: H3-(H2+2H1) is greater than or equal to 6.5 mm and less than or equal to 10 mm.

23. The battery cell according to any one of claims 20 to 22, wherein: The electrode assembly includes a positive electrode sheet, a negative electrode sheet and a separator arranged between the positive electrode sheet and the negative electrode sheet, the first electrode region includes the positive electrode sheet, the separator and the negative electrode sheet arranged in a stacked manner; the second electrode region includes the negative electrode sheet and the separator arranged in a stacked manner, or the second electrode region includes the negative electrode sheet.

24. The battery cell according to any one of claims 15 to 19, wherein: The buffer member is arranged on the side of the electrode assembly along the first direction, the electrode assembly includes an electrode body and a pole ear arranged at the end of the electrode body, the electrode body includes a third electrode area and a fourth electrode area, the thickness of the pole piece of the electrode assembly in the third electrode area is less than the thickness in the fourth electrode area, the buffer member has a third buffer area and a fourth buffer area, the third buffer area is arranged corresponding to the third electrode area, the fourth buffer area is arranged corresponding to the fourth electrode area, and the compressibility of the third buffer area is less than the compressibility of the fourth buffer area.

25. The battery cell according to claim 24, wherein: There are two third buffer regions, and the two third buffer regions are respectively located on both sides of the fourth buffer region along the second direction, and the first direction intersects with the second direction. In the second direction, the size of the third buffer area is H4, the size of the fourth buffer area is H5, and the size of the electrode body is H3, wherein H3-(H5+2H4) is greater than or equal to -2.5mm and less than or equal to 20mm, and H4 is greater than or equal to 1mm and less than or equal to 10mm.

26. The battery cell according to claim 25, wherein: H3-(H5+2H4) is greater than or equal to 6.5 mm and less than or equal to 13 mm.

27. A battery, wherein: Comprising the battery cell according to any one of claims 1-26.

28. An electrical device, wherein: The battery as claimed in claim 27 is used to provide electrical energy to the electrical device.

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