Battery device and electric device

Abstract

Provided in the present application are a battery device and an electric device. The battery device comprises an end plate, a buffer member, and a plurality of battery cells. The plurality of battery cells are disposed on the same side of the end plate in a first direction, the plurality of battery cells are stacked, the battery cell of the plurality of battery cells closest to the end plate is a first battery cell, and the first battery cell comprises a housing and an end cap. An opening is provided at at least one end of the housing in a second direction, and the housing comprises a first wall disposed facing the end plate in the first direction. The first wall comprises a first region and a second region arranged in the second direction, the first region having a greater thickness than the second region. The end cap closes the opening, the end cap disposed the first wall are welded to form a connecting portion, and in the second direction, the first region is located between the second region and the connecting portion. The buffer member is at least partially disposed between the first region and the end plate in the first direction. The risk of affecting the reinforcing effect of the first region due to rigid contact between the end plate and the first region is reduced, and the service life of the battery device is effectively prolonged.

Description

Battery devices and electrical appliances Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to a battery device and an electrical device. Background Technology

[0002] Energy conservation and emission reduction are key to the sustainable development of the automotive industry, and electric vehicles, due to their energy-saving and environmentally friendly advantages, have become an important component of this sustainable development. For electric vehicles, battery technology is a crucial factor in their development.

[0003] In battery technology, the lifespan of battery devices is a crucial factor. Therefore, improving the lifespan of battery devices is a pressing technical problem that needs to be solved.

[0004] Summary of the Invention

[0005] This application provides a battery device and an electrical device that can improve the service life of the battery device.

[0006] In a first aspect, embodiments of this application provide a battery device, including an end plate, a buffer, and a plurality of battery cells; the plurality of battery cells are disposed on the same side of the end plate along a first direction, and the plurality of battery cells are stacked along the first direction, the battery cell closest to the end plate among the plurality of battery cells is a first battery cell, the first battery cell including a housing, an end cap, and an electrode assembly; the housing has an opening at at least one end along a second direction, the housing including a first wall disposed facing the end plate along the first direction, the first wall including a first region and a second region arranged along the second direction, the thickness of the first region being greater than the thickness of the second region, the second direction intersecting the first direction; the end cap closes the opening, the end cap is welded to the first wall to form a connection portion, the first region is located between the second region and the connection portion along the second direction; the electrode assembly is at least partially housed within the housing; the buffer is at least partially disposed along the first direction between the first region and the end plate.

[0007] In the above technical solution, the thickness of the first region is greater than that of the second region, and the first region is located between the connecting portion and the second region along the second direction. This makes the thicker first region closer to the connecting portion than the second region. The first region strengthens the area of ​​the first wall near the connecting portion, thereby reducing the risk of fatigue cracking in this area. Furthermore, a buffer is at least partially disposed between the first region and the end plate along the first direction. The buffer acts as a buffer between the first region and the end plate, reducing the risk that the rigid contact between the end plate and the first region will affect the strengthening effect of the first region. This allows the first region to exert a greater strengthening effect on the area of ​​the first wall near the connecting portion, improving the service life of the battery cell and thus effectively increasing the service life of the battery device.

[0008] In some embodiments, along a first direction, the second region has a first outer surface facing the exterior of the housing, and the first region includes a first protrusion protruding from the first outer surface, with a buffer member at least partially located between the first protrusion and the end plate. With a fixed thickness, the partial protrusion of the first region from the first outer surface reduces the space occupied by the first region within the housing, freeing up more space for the electrode assembly. The buffer member, at least partially located between the first protrusion and the end plate, acts as a buffer between the first protrusion and the end plate, reducing the risk of rigid contact between the end plate and the first protrusion affecting the reinforcement effect of the first region.

[0009] In some embodiments, a recess is formed at a position corresponding to the first protrusion in the buffer member, and the first protrusion is at least partially accommodated within the recess. This allows at least a portion of the first protrusion to be embedded within the buffer member, reducing the overall size of the end plate, buffer member, and first battery cell along the first direction. This results in a more compact structure for the end plate, buffer member, and first battery cell, improving space utilization and ultimately increasing the volumetric energy density of the battery device.

[0010] In some embodiments, along the first direction, the maximum thickness of the buffer is T, and the maximum thickness of the first protrusion is L1, where L1 < T. Even if the first protrusion is fully embedded in the buffer, it is not easy to cause rigid contact between the end plate and the first protrusion.

[0011] In some embodiments, along a first direction, the second region has a first inner surface, which is disposed opposite to the first outer surface, and a portion of the first region protrudes from the first inner surface. This allows the first region to have both portions protruding from the first outer surface and portions protruding from the first inner surface. Given a fixed thickness of the first region, neither the thickness of the portion protruding from the first outer surface nor the thickness of the portion protruding from the first inner surface is excessive, thus reducing the first region's occupancy of the internal or external space of the housing.

[0012] In some embodiments, the first region further includes a second protrusion protruding from the first inner surface. Along the first direction, the maximum thickness of the first protrusion is L1, and the maximum thickness of the second protrusion is L2, where L1 > L2. The first protrusion has a larger maximum thickness, and the second protrusion has a smaller maximum thickness. With a fixed thickness in the first region, the second protrusion reduces its occupation of the internal space of the housing, thereby freeing up more space for the electrode assembly and improving the volumetric energy density of the battery cell.

[0013] In some embodiments, 0.05mm ≤ L1 ≤ 1.2mm.

[0014] In some embodiments, 0.05mm ≤ L2 ≤ 1mm.

[0015] In some embodiments, the orthographic projection of the buffer and the orthographic projection of the end plate both cover the first region along the first direction. This increases the area of ​​the portion of the buffer located between the end plate and the first region, thereby providing better cushioning between the end plate and the first region.

[0016] In some embodiments, the first region is pressed against the end plate by a buffer. This makes the structure of the first region, the buffer, and the end plate more compact, which is beneficial for improving the volumetric energy density of the battery device.

[0017] In some embodiments, along the first direction, a portion of the buffer is disposed between the second region and the end plate. The buffer acts as a buffer between the second region and the end plate, reducing the risk of rigid contact between the end plate and the second region affecting the reinforcement effect of the first region.

[0018] In some embodiments, along the first direction, the orthographic projection of the buffer and the orthographic projection of the end plate both cover the second region. This increases the area of ​​the portion of the buffer located between the end plate and the second region, thereby providing better cushioning between the end plate and the second region.

[0019] In some embodiments, the second region is pressed against the end plate by a buffer. This makes the structure of the second region, the buffer, and the end plate more compact, which is beneficial for improving the volumetric energy density of the battery device.

[0020] In some embodiments, the thermal conductivity of the buffer is less than or equal to 0.06 W / (m·K). This gives the buffer good thermal insulation capabilities and reduces the heat transfer between the first battery cell and the end plate.

[0021] In some embodiments, the buffer is a cushioning pad made of insulating material. This allows the insulating element to serve both a cushioning and insulating function, thereby achieving insulation isolation between the first zone and the end plate.

[0022] In some embodiments, the first wall further includes a transition region connected to the end of the first region away from the second region along a second direction. The transition region is connected to a connecting portion, and the connection point between the transition region and the connecting portion forms a connection interface. The connection interface has a first position closest to the first region along the second direction, located at the end of the first region away from the second region along the second direction. The connection interface formed by the connection point between the transition region and the connecting portion provides a sufficiently large contact area, improving the robustness of the first wall after welding to the end cap.

[0023] In some embodiments, at least a portion of the connection interface extends obliquely relative to a first direction. After the end cap and the first wall are welded, the connection shrinks as it solidifies, generating tensile stress in the transition region. When the first wall is subjected to the expansion force of the electrode assembly, it deforms, generating tensile stress in the transition region on the connection. Because the connection interface extends obliquely relative to the first direction, the tensile stress generated by the connection due to shrinkage in the transition region near the portion of the connection interface that extends obliquely relative to the first direction is not in the same direction as the tensile stress generated by the transition region due to deformation of the first wall, reducing the risk of fatigue cracking in the area of ​​the transition region near the connection interface.

[0024] In some embodiments, the connection interface includes a first interface that extends obliquely from a first position toward the end cap. Along a first direction, at least a portion of the transition region is located between the first interface and the end cap. The connection portion protects the transition region. When the first wall is subjected to the expansion force of the electrode assembly, the deformation of the transition region during the stress process is blocked by the connection portion, reducing the risk of fatigue cracking in the area of ​​the transition region near the first interface.

[0025] In some embodiments, the first interface is connected to the outer surface of the first region at a first location. This brings the first region closer to the connection in the second direction, further reducing the risk of fatigue cracking of the area of ​​the first wall near the connection due to the expansion of the electrode assembly.

[0026] In some embodiments, the connection interface includes a second interface that extends obliquely from the first position toward the end cap. Along the first direction, at least a portion of the transition region is located on the side of the second interface away from the end cap. This allows the transition region to restrict the connection, reducing the risk of the connection detaching.

[0027] In some embodiments, the second interface is connected to the inner surface of the first region at a first location. This brings the first region closer to the connection in the first direction, further reducing the risk of fatigue cracking of the area of ​​the first wall near the connection due to the expansion of the electrode assembly.

[0028] In some embodiments, the Vickers hardness of the transition zone is less than that of the second zone; and / or, the Vickers hardness of the transition zone is less than that of the connecting portion. If the Vickers hardness of the transition zone is less than that of the second zone, the transition zone with lower Vickers hardness connects with the connecting portion, which can alleviate the rigid tension between the first wall and the connecting portion when the first wall deforms, reducing the risk of separation between the first wall and the connecting portion. If the Vickers hardness of the transition zone is less than that of the connecting portion, the transition zone is more prone to deformation than the connecting portion, which can alleviate the rigid tension between the first wall and the connecting portion when the first wall deforms, reducing the risk of separation between the first wall and the connecting portion.

[0029] In some embodiments, at least a portion of the Vickers hardness of the first region is less than that of the second region. When the second region deforms under the expansion force of the electrode assembly, the region in the first region with a lower Vickers hardness than the second region can reduce the impact of the deformation of the second region on the area of ​​the first wall near the connection, thereby reducing the risk of fatigue cracking of the area of ​​the first wall near the connection due to the expansion of the electrode assembly.

[0030] In some embodiments, the electrode assembly includes a positive electrode and a negative electrode, with at least a portion of the positive electrode and at least a portion of the negative electrode stacked along a first direction, and the first wall being the wall with the largest outer surface area in the housing. Because at least a portion of the positive electrode and at least a portion of the negative electrode are stacked along the first direction, the electrode assembly expands significantly along the first direction during cycling, making the first region of the first wall more susceptible to compression from the end plate. In this embodiment, a buffer is provided between the first region and the end plate, effectively reducing the risk of rigid contact between the end plate and the first region when the electrode assembly expands.

[0031] In some embodiments, the electrode assembly has a flat region, and portions of the positive electrode and negative electrode located in the flat region are stacked along a first direction. The first direction is the stacking direction of the portions of the positive and negative electrode located in the flat region. During cycling, the electrode assembly expands more along the first direction, and the first wall is more significantly affected by this expansion. Because the first region reinforces the area of ​​the first wall near the connection, the risk of fatigue cracking of the first wall near the connection due to electrode assembly expansion is reduced.

[0032] In some embodiments, the electrode assembly is a wound structure, and the electrode assembly further has a corner region. The corner region is located at at least one end of the straight region along a third direction. The first direction, the second direction, and the third direction are not coplanar and intersect each other. For the wound electrode assembly, the straight region expands more in the second direction. Since the first region reinforces the area of ​​the first wall near the connection, the risk of fatigue cracking of the first wall near the connection due to the expansion of the electrode assembly can be effectively reduced.

[0033] In some embodiments, the electrode assembly is a stacked structure, and the flat region includes multiple positive electrode sheets and multiple negative electrode sheets, which are stacked along a first direction. For the stacked electrode assembly, the expansion amount of the electrode assembly in the stacking direction of the positive and negative electrode sheets is greater. Since the first region strengthens the area of ​​the first wall near the connection, the risk of fatigue cracking of the first wall near the connection due to the expansion of the electrode assembly can be effectively reduced.

[0034] Secondly, embodiments of this application also provide an electrical device, including the battery device provided in any one of the embodiments of the first aspect. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 is a structural schematic diagram of a vehicle provided in some embodiments of this application;

[0037] Figure 2 is an isometric view of a battery device provided in some embodiments of this application;

[0038] Figure 3 is an isometric view of the battery device shown in Figure 2 after the second housing has been removed;

[0039] Figure 4 is a magnified view of part A in Figure 3;

[0040] Figure 5 is an exploded view of a single battery cell provided in some embodiments of this application;

[0041] Figure 6 is a schematic diagram of the structure of the battery cell shown in Figure 5;

[0042] Figure 7 is a magnified view of part B in Figure 6;

[0043] Figure 8 is a schematic diagram of the structure of a battery device provided in some embodiments of this application;

[0044] Figure 9 is a magnified view of part C in Figure 8;

[0045] Figure 10 shows the positional relationship between the first wall and the buffer component as shown in Figure 9;

[0046] Figure 11 is a diagram showing the positional relationship between the first wall and the buffer element according to some other embodiments of this application;

[0047] Figure 12 is a partial view of a first battery cell provided in some embodiments of this application;

[0048] Figure 13 is a magnified view of part D in Figure 12;

[0049] Figure 14 is a partial view of a first battery cell provided in some other embodiments of this application;

[0050] Figure 15 is a magnified view of a portion of point E in Figure 14;

[0051] Figure 16 is a partial view of a first battery cell provided in some embodiments of this application;

[0052] Figure 17 is a magnified view of part F in Figure 16;

[0053] Figure 18 is an isometric view of the housing provided in some embodiments of this application;

[0054] Figure 19 is an isometric view of an electrode assembly provided in some embodiments of this application;

[0055] Figure 20 is a schematic diagram of the electrode assembly shown in Figure 19;

[0056] Figure 21 is an isometric view of an electrode assembly provided in some other embodiments of this application;

[0057] Figure 22 is a schematic diagram of the electrode assembly shown in Figure 21.

[0058] Icons: 1-Outer shell; 11-Housing shell; 111-First wall; 1111-First region; 11111-First protrusion; 11112-Second protrusion; 1112-Second region; 11121-First outer surface; 11122-First inner surface; 1113-Transition region; 112-Second wall; 12-End cap; 2-Electrode assembly; 21-Electrode tab; 22-Positive electrode; 23-Negative electrode; 24-Isolator; 25-Straight region; 26-Corner region; 3-Electrode terminal; 4-Current collector; 5-Pressure relief mechanism; 6-Insulating component; 7 - Connecting part; 71- Connecting interface; 71a- First interface; 71b- Second interface; 711- First position; 712- Second position; 713- Third position; 10- Battery cell; 10a- First battery cell; 20- Housing; 201- First housing; 202- Second housing; 30- End plate; 40- Separator; 50- Buffer; 501- Recess; 100- Battery assembly; 200- Controller; 300- Motor; 1000- Vehicle; W- First interface; X- First direction; Z- Second direction; Y- Third direction. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0060] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0061] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0062] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0063] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0064] In this application, "multiple" means two or more (including two).

[0065] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0066] Battery cells include, but are not limited to, lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-metal hydride batteries, nickel-cadmium batteries, lead-acid batteries, etc.

[0067] A single battery cell typically includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of a single battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, reduces the risk of short circuits while allowing active ions to pass through.

[0068] In some embodiments, the positive electrode can be a positive electrode sheet, which may include a positive current collector and a positive active material disposed on at least one surface of the positive current collector.

[0069] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.

[0070] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, it can be aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0071] As an example, the positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials in battery cells may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxide may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds.

[0072] In some embodiments, the positive electrode can be a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloys, etc. When foamed metal is used as the positive electrode, the surface of the foamed metal may or may not contain a positive electrode active material. As an example, lithium source material, potassium metal, or sodium metal can also be filled and / or deposited within the foamed metal, where the lithium source material is lithium metal and / or a lithium-rich material.

[0073] In some embodiments, the negative electrode can be a negative electrode sheet, and the negative electrode sheet can include a negative current collector.

[0074] As an example, the negative electrode current collector can be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, it can be aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium, etc. Foamed metal can be nickel foam, copper foam, aluminum foam, foam alloy, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0075] As an example, the negative electrode sheet may include a negative current collector and a negative active material disposed on at least one surface of the negative current collector.

[0076] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0077] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials in battery cells may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0078] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0079] In some embodiments, the separator is a separator membrane. The separator membrane can be any known porous structure separator membrane with good chemical and mechanical stability.

[0080] As an example, the material of the separator may include at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different. The separator may be a separate component located between the positive and negative electrodes, or it may be attached to the surfaces of the positive and negative electrodes.

[0081] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0082] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The electrolyte can be liquid, gel-like, or solid. Liquid electrolytes include electrolyte salts and solvents.

[0083] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0084] In some embodiments, the solvent may include at least one selected from ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may include one or more selected from ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0085] Among them, the gel electrolyte includes a polymer as the electrolyte backbone network, combined with an ionic liquid - lithium salt.

[0086] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0087] As an example, polymer solid electrolytes can be polyether (polyoxyethylene), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids-lithium salts, cellulose, etc.

[0088] As an example, inorganic solid electrolytes may include one or more of the following: oxide solid electrolytes (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON thin film), sulfide solid electrolytes (crystalline lithium superconducting ion conductor (lithium germanium phosphate sulfide, silver sulfide germanium ore), amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0089] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0090] In some embodiments, the electrode assembly is a wound structure. The positive electrode and the negative electrode are wound into a wound structure.

[0091] In some implementations, the electrode assembly is a stacked structure.

[0092] As an example, multiple positive and negative electrode plates can be set, and multiple positive and multiple negative electrode plates can be stacked alternately.

[0093] As an example, multiple positive electrode sheets can be set, and negative electrode sheets are folded to form multiple stacked folded segments, with a positive electrode sheet sandwiched between adjacent folded segments.

[0094] As an example, both the positive and negative electrode sheets are folded to form multiple stacked folded segments.

[0095] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0096] As an example, the separator can be continuously arranged between any adjacent positive or negative electrode plates by folding or rolling.

[0097] In some embodiments, the electrode assembly can be cylindrical, flat, or polygonal, etc.

[0098] In some embodiments, the electrode assembly is provided with tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0099] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as electrode assemblies and electrolytes. The housing may be made of steel, aluminum, plastic (such as polypropylene), composite metal (such as copper-aluminum composite), or aluminum-plastic film, etc.

[0100] As an example, a battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include prismatic battery cells, blade-shaped battery cells, and multi-prismatic battery cells, such as hexagonal prismatic battery cells.

[0101] The battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells, which are connected in series, parallel, or mixed connections via a busbar.

[0102] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells; as an example, a battery cell assembly can be a battery module, which is formed by arranging multiple battery cells and fixing them together to form an independent module.

[0103] As an example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0104] In some embodiments, the battery device may be a battery pack, which may include a housing and one or more individual battery cells housed within the housing.

[0105] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0106] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0107] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0108] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0109] As an example, the housing can be part of the vehicle's chassis structure. For instance, the housing's roof can be at least part of the vehicle's floor, or the housing's frame can be at least part of the vehicle's crossbeams and longitudinal beams.

[0110] In some embodiments, the battery device refers to an energy storage device, which includes a housing with a door on at least one side. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0111] In a single battery cell, the cell may include a casing and electrode assemblies. The casing may include a housing and end caps. The housing has an opening. After the electrode assemblies are installed inside the housing, the opening can be closed by the end caps. The end caps can be welded to the housing. After the end caps are welded to the housing, the welded joint between the end caps and the housing wall forms a connection. The area of ​​the housing wall near the connection will form a heat-affected zone due to the high temperature of welding, and the strength of the portion of the housing wall in the heat-affected zone will be reduced. During the charge-discharge cycle of the battery cell, the electrode assemblies expand. The housing wall, subjected to the expansion force of the electrode assemblies, will deform. Over time, this can easily lead to fatigue cracking in the area of ​​the housing wall near the connection (heat-affected zone).

[0112] Therefore, to reduce the risk of fatigue cracking in the area of ​​the casing wall near the connection, the area of ​​the casing wall near the connection can be locally thickened. However, in battery devices, end plates are generally installed at the ends of multiple battery cells to constrain them. The end plates may compress the thickened area of ​​the casing wall, especially when the battery cells expand, causing the end plates to form rigid contact with the thickened area of ​​the casing wall. This weakens the reinforcing effect of the thickened area of ​​the casing wall and affects the service life of the battery cells.

[0113] In view of this, the present application provides a technical solution in which the battery device includes an end plate, a buffer member, and a plurality of battery cells; the plurality of battery cells are disposed on the same side of the end plate along a first direction, and the plurality of battery cells are stacked along the first direction, the battery cell closest to the end plate among the plurality of battery cells is the first battery cell, the first battery cell includes a housing, an end cap, and an electrode assembly; the housing has an opening at at least one end along a second direction, the housing includes a first wall disposed facing the end plate along the first direction, the first wall includes a first region and a second region arranged along the second direction, the thickness of the first region is greater than the thickness of the second region, and the second direction intersects the first direction; the end cap closes the opening, the end cap is welded to the first wall to form a connection part, and along the second direction, the first region is located between the second region and the connection part; the electrode assembly is at least partially housed in the housing; the buffer member is at least partially disposed along the first direction between the first region and the end plate.

[0114] In such a battery device, a buffer is provided. The buffer is at least partially disposed between the first region and the end plate along the first direction. The buffer plays a buffering role between the first region and the end plate, reducing the risk that the reinforcement effect of the first region will be affected by the rigid contact between the end plate and the first region. This allows the first region to exert a greater reinforcement effect on the area of ​​the first wall near the connection, improving the service life of the battery cell and thus effectively improving the service life of the battery device.

[0115] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use battery cells and battery devices, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships and spacecraft, etc. For example, spacecraft include airplanes, rockets, space shuttles and spacecraft.

[0116] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0117] Please refer to Figure 1, which is a structural schematic diagram of a vehicle 1000 provided in some embodiments of this application. A battery device 100 is disposed inside the vehicle 1000, and the battery device 100 may be located at the bottom, front, or rear of the vehicle 1000. The battery device 100 can be used to power the vehicle 1000; for example, the battery device 100 can serve as the operating power source for the vehicle 1000.

[0118] The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery device 100 to supply power to the motor 300, for example, for the power needs of the vehicle 1000 during startup, navigation and driving.

[0119] In some embodiments of this application, the battery device 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0120] Please refer to Figures 2 and 3. Figure 2 is an isometric view of a battery device 100 provided in some embodiments of this application; Figure 3 is an isometric view of the battery device 100 shown in Figure 2 after removing the second housing 202. The battery device 100 may include a battery cell 10 and a housing 20, the housing 20 being used to house the battery cell 10.

[0121] The housing 20 has an enclosed space inside for accommodating the battery cells 10. The housing 20 can have various structures. In some embodiments, the housing 20 may include a first housing 201 and a second housing 202, which are interlocked. The first housing 201 and the second housing 202 can have various shapes, such as cuboids or cylinders. The first housing 201 can be a hollow structure open on one side, and the second housing 202 can also be a hollow structure open on one side. The open side of the second housing 202 interlocks with the open side of the first housing 201, thus forming a housing 20 with an enclosed space. Alternatively, the first housing 201 can be a hollow structure open on one side, and the second housing 202 can be a plate-like structure, with the second housing 202 interlocked with the open side of the first housing 201, thus forming a housing 20 with a accommodating space.

[0122] In the battery device 100, there can be multiple battery cells 10. These multiple battery cells 10 can be connected in series, parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells 10 are connected in both series and parallel configurations. Alternatively, multiple battery cells 10 can be first connected in series, parallel, or in a mixed configuration to form a battery module, and then multiple battery modules can be connected in series, parallel, or in a mixed configuration to form a whole, which is then housed within the housing 20. Another option is that all battery cells 10 can be directly connected in series, parallel, or in a mixed configuration, and then the whole assembly of all battery cells 10 is housed within the housing 20.

[0123] In some embodiments, please refer to FIG4, which is a partial enlarged view of point A in FIG3. The battery device 100 may include an end plate 30 and a plurality of battery cells 10, the plurality of battery cells 10 being disposed on one side of the end plate 30.

[0124] There can be one or more end plates 30. If there are multiple end plates 30, two adjacent end plates 30 cooperate to constrain multiple battery cells 10.

[0125] In this embodiment, the battery device 100 may or may not include a housing 20. If the battery device 100 includes a housing 20, the end plate 30 may be a wall within the housing 20 or a beam fixed inside the housing 20.

[0126] In some embodiments, the battery device 100 may further include a separator 40 disposed between two adjacent battery cells 10.

[0127] The separator 40 can be a thermal management component, a heat insulation pad, a buffer pad, etc. The thermal management component can be a heating component that heats up the battery cell 10, or a cooling component that cools down the battery cell 10.

[0128] As an example, in the embodiment shown in Figure 4, the end plate 30 is a beam fixed inside the housing 20. The battery device 100 has two end plates 30, which are arranged opposite each other along a first direction X. Multiple rows of battery cells 10 are arranged between the two end plates 30. Multiple battery cells 10 in each row are arranged along the first direction X. A separator 40, which is a thermal management component, is provided between adjacent battery cells 10 along the first direction X.

[0129] Please refer to Figures 5-7. Figure 5 is an exploded view of a battery cell 10 provided in some embodiments of this application; Figure 6 is a structural schematic diagram of the battery cell 10 shown in Figure 5; Figure 7 is a partial enlarged view of point B in Figure 6. The battery cell 10 may include a housing 1 and an electrode assembly 2, with the electrode assembly 2 housed within the housing 1.

[0130] In some embodiments, the housing 1 may include a housing 11 and an end cap 12. The housing 11 has an opening at at least one end along the second direction Z, and the end cap 12 corresponds to the opening one-to-one, closing the opening of the housing 11. Here, "closing" means covering or shutting off, which can be either sealed or unsealed.

[0131] The housing 11 is a component used to house the electrode assembly 2. The housing 11 can be a hollow structure with an opening at one end, or it can be a hollow structure with openings at both opposite ends. The housing 11 can have various shapes, such as cylindrical or cuboid. The housing 11 can be made of various materials, such as copper, iron, aluminum, steel, or aluminum alloy. The electrode assembly 2 can be partially or completely housed within the housing 11.

[0132] The end cap 12 and the housing 11 together define a receiving space for accommodating the electrode assembly 2 and other components. The end cap 12 can be welded to the housing 11 to close the opening of the housing 11. The shape of the end cap 12 can be adapted to the shape of the housing 11; for example, if the housing 11 is a cuboid structure, the end cap 12 can be a rectangular plate structure adapted to the housing 11. The end cap 12 can also be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, etc. The end cap 12 and the housing 11 can be made of the same or different materials.

[0133] In an embodiment where the housing 11 has an opening at one end, one end cap 12 may be provided accordingly. In an embodiment where the housing 11 has openings at both opposite ends, two end caps 12 may be provided accordingly, with the two end caps 12 respectively closing the two openings of the housing 11, and the two end caps 12 and the housing 11 together defining the receiving space.

[0134] In some embodiments, the battery cell 10 may further include electrode terminals 3, which are disposed on the housing 1 and are used for electrical connection with the tabs 21 of the electrode assembly 2 to input or output electrical energy of the battery cell 10. The electrode terminals 3 may be disposed on the housing 11 of the housing 1 or on the end cap 12 of the housing 1. The electrode terminals 3 and the tabs 21 may be directly connected, for example, by welding. Alternatively, the electrode terminals 3 and the tabs 21 may be indirectly connected, for example, through a current collector 4. The current collector 4 may be a metallic conductor, such as copper, iron, aluminum, steel, or aluminum alloy.

[0135] In some embodiments, the battery cell 10 may further include a pressure relief mechanism 5, which may be disposed on the end cap 12 or the housing 11. The pressure relief mechanism 5 may be a pressure relief component installed on the housing 11 or the end cap 12, such as an explosion-proof plate or a safety valve. The pressure relief mechanism 5 may also be integrally formed with the end cap 12 or the housing 11. The pressure relief mechanism 5 may be provided with a pressure relief groove to split along the pressure relief groove when the battery cell 10 is depressurized. The pressure relief groove may be a groove extending along a closed trajectory, which may be a circular trajectory, a rectangular trajectory, etc.; the pressure relief groove may also be a groove extending along a non-closed trajectory, which may be an H-shaped trajectory, a Y-shaped trajectory, a V-shaped trajectory, a U-shaped trajectory, etc.

[0136] As an example, as shown in Figures 5-7, one end of the housing 11 forms an opening, and there is one end cap 12 in the housing 1, which closes one opening of the housing 11. The end cap 12 is provided with a pressure relief mechanism 5, and two electrode terminals 3 are provided on the end cap 12, which are a positive electrode terminal and a negative electrode terminal, respectively. The end of the electrode assembly 2 facing the end cap 12 has two tabs 21, which are a positive electrode tab and a negative electrode tab, respectively. The positive electrode terminal is connected to the positive electrode tab through a current collector 4, and the negative electrode terminal is connected to the negative electrode tab through another current collector 4. An insulating member 6 is provided on the side of the end cap 12 facing the electrode assembly 2, which is used to insulate and isolate the end cap 12 and the current collector 4.

[0137] Please refer to Figures 8 and 9. Figure 8 is a structural schematic diagram of a battery device 100 provided in some embodiments of this application; Figure 9 is a partial enlarged view of point C in Figure 8. This application provides a battery device 100, including an end plate 30, a buffer member 50, and a plurality of battery cells 10. The plurality of battery cells 10 are disposed on the same side of the end plate 30 along a first direction X. Along the first direction X, the plurality of battery cells 10 are stacked. The battery cell 10 closest to the end plate 30 among the plurality of battery cells 10 is the first battery cell 10a. The first battery cell 10a includes a housing 11, an end cap 12, and an electrode assembly 2. The housing 11 has an opening at at least one end along a second direction Z. The housing 11 includes a first wall 111 disposed along the end plate 30 in the first direction X. The first wall 111 includes a first region 1111 and a second region 1112 arranged along the second direction Z. The thickness of the first region 1111 is greater than the thickness of the second region 1112. The second direction Z intersects the first direction X. End cap 12 closes the opening and is welded to the first wall 111 to form a connection portion 7. Along the second direction Z, the first region 1111 is located between the second region 1112 and the connection portion 7. The electrode assembly 2 is at least partially housed within the housing 11. Along the first direction X, the buffer 50 is at least partially disposed between the first region 1111 and the end plate 30.

[0138] The battery device 100 can have one or more end plates 30. If there is one end plate 30, it can cooperate with other components to constrain multiple battery cells 10, such as thermal management components. If there are multiple end plates 30, they can be arranged along a first direction X, with adjacent end plates 30 cooperating to constrain multiple battery cells 10. The end plates 30 can extend along a third direction Y, where the first direction X, the second direction Z, and the third direction Y are not coplanar and intersect each other. Any two of the first direction X, the second direction Z, and the third direction Y can be set at acute, right, or obtuse angles. As an example, the first direction X, the second direction Z, and the third direction Y are perpendicular to each other.

[0139] The battery device 100 may include at least one row of battery cells 10, each row of battery cells 10 including multiple battery cells 10, the multiple battery cells 10 in each row being disposed on the same side of the end plate 30 along the first direction X, and the multiple battery cells 10 in each row being stacked along the first direction X. As an example, there are two end plates 30, and multiple rows of battery cells 10 are disposed between the two end plates 30, the multiple rows of battery cells 10 being arranged along the third direction Y.

[0140] The first battery cell 10a is the battery cell 10 closest to the end plate 30 in each row of battery cells 10. Along the first direction X, if end plates 30 are provided on both sides of each row of battery cells 10, the battery cells 10 located at both ends of each row are all first battery cells 10a. In each row of battery cells 10, the structure of the battery cells 10 other than the first battery cell 10a can be the same as or different from the structure of the first battery cell 10a. Taking the example that the structure of the battery cells 10 other than the first battery cell 10a is different from the structure of the first battery cell 10a, in the battery cells 10 other than the first battery cell 10a, the walls arranged along the first direction X in the casing 11 can be of uniform thickness, without forming a first region 1111 and a second region 1112 of unequal thickness.

[0141] The first wall 111 is the wall portion of the housing 11 facing the end plate 30. The thickness direction of the first wall 111 is parallel to the first direction X. The first wall 111 can be the wall with the largest outer surface area in the housing 11, or it may not be the wall with the largest outer surface area in the housing 11. There can be one or two first walls 111 in the housing 11. Taking two first walls 111 in the housing 11 as an example, along the first direction X, one first wall 111 can be set facing one end plate 30, and the other first wall 111 can be set facing the other end plate 30.

[0142] The first region 1111 can be a region where the thickness of the first wall 111 is increased, and the first region 1111 is thicker than the second region 1112. The thickness direction of the first region 1111 and the thickness direction of the second region 1112 are both parallel to the first direction X. The first region 1111 can be directly connected to the connecting part 7 or indirectly connected. The first region 1111 can be a structure of equal thickness or a structure of unequal thickness; the second region 1112 can be a structure of equal thickness or a structure of unequal thickness. If at least one of the first region 1111 and the second region 1112 is a structure of unequal thickness, the maximum thickness of the second region 1112 can be less than or equal to the minimum thickness of the first region 1111, so that the thickness of the first region 1111 is greater than the thickness of the second region 1112. As an example, the first region 1111 is a non-uniform thickness structure. The first region 1111 includes a first part and a second part. The thickness of the second part is less than the thickness of the first part. The second part is located in the first part and the second region 1112 and connects the first part and the second region 1112. The thickness of the second part decreases along the direction from the first part to the second region 1112.

[0143] In an embodiment where there is one end cap 12 in the housing 1, there is one first region 1111 in the first wall 111; in an embodiment where there are two end caps 12 in the housing 1, there are two first regions 1111 in the first wall 111, and along the second direction Z, the second region 1112 is located between the two first regions 1111.

[0144] The second region 1112 has a first outer surface 11121 (shown in FIG. 7) facing the outside of the housing 11 and a first inner surface 11122 (shown in FIG. 7) facing the inside of the housing 11. It can be that a part of the first region 1111 protrudes from the first outer surface 11121 and the inner surface of the first region 1111 is coplanar with the first inner surface 11122, or a part of the first region 1111 protrudes from the first inner surface 11122 and the outer surface of the first region 1111 is flush with the first outer surface 11121, or a part of the first region 1111 protrudes from the first outer surface 11121 and another part of the first region 1111 protrudes from the first inner surface 11122.

[0145] The electrode assembly 2 can be partially or completely housed within the housing 11. The electrode assembly 2 is located within the receiving space defined by the housing 11 and the end cap 12. The electrode assembly 2 can be a stacked structure or a wound structure. There can be one or more electrode assemblies 2 within the housing 11. If there are multiple electrode assemblies 2, they can be stacked, for example, multiple electrode assemblies 2 can be stacked along a first direction X.

[0146] The end cap 12 can be welded to the housing 11 to achieve fixation and sealing between the end cap 12 and the housing 11. The connecting part 7 is the weld mark formed after the end cap 12 and the first wall 111 of the housing 11 are welded together. The connecting part 7 can be formed by the welded and fused parts of the end cap 12 and the first wall 111. The connecting part 7 can correspond one-to-one with the first area 1111. A part of the connecting part 7 can be formed on the end cap 12 and another part can be formed on the first wall 111. The first wall 111 and the end cap 12 can form the connecting part 7 by seam welding or by through welding.

[0147] The buffer 50 is a component capable of elastic deformation when the first wall 111 and the end plate 30 are pressed together. The buffer 50 can be an elastic component made of metal or an elastic component made of insulating material. The metal material can be copper, iron, aluminum, steel, aluminum alloy, etc. The insulating material can be rubber, plastic, etc.

[0148] The buffer member 50 is at least partially disposed between the first region 1111 and the end plate 30 along the first direction X, such that in a projection plane perpendicular to the first direction X, the orthographic projections of the buffer member 50, the first region 1111, and the end plate 30 overlap. The first region 1111 and the end plate 30 are disposed opposite each other along the first direction X. The buffer member 50 may be partially disposed between the first region 1111 and the end plate 30, or it may be entirely disposed between the first region 1111 and the end plate 30. The buffer member 50 may be in contact with the first region 1111 or be spaced apart; the buffer member 50 may be in contact with the end plate 30 or be spaced apart.

[0149] In this embodiment, the thickness of the first region 1111 is greater than the thickness of the second region 1112, and the first region 1111 is located between the connecting portion 7 and the second region 1112 along the second direction Z. This makes the thicker first region 1111 closer to the connecting portion 7 than the second region 1112. The first region 1111 strengthens the area of ​​the first wall 111 near the connecting portion 7, thereby reducing the risk of fatigue cracking in the area of ​​the first wall 111 near the connecting portion 7. In addition, the buffer member 50 is at least partially disposed between the first region 1111 and the end plate 30 along the first direction X. The buffer member 50 acts as a buffer between the first region 1111 and the end plate 30, reducing the risk that the strengthening effect of the first region 1111 will be affected by the rigid contact between the end plate 30 and the first region 1111. This allows the first region 1111 to exert a greater strengthening effect on the area of ​​the first wall 111 near the connecting portion 7, improving the service life of the battery cell 10 and thus effectively improving the service life of the battery device 100.

[0150] In some embodiments, please refer to FIG10, which is a positional relationship diagram of the first wall 111 and the buffer member 50 shown in FIG9. Along the first direction X, the second region 1112 has a first outer surface 11121 facing the outside of the housing 11. The first region 1111 includes a first protrusion 11111 protruding from the first outer surface 11121. The buffer member 50 is at least partially located between the first protrusion 11111 and the end plate 30 (shown in FIG9).

[0151] The second region 1112 has a first inner surface 11122 facing the interior of the housing 11, and the first inner surface 11122 and the first outer surface 11121 are disposed opposite to each other. The first outer surface 11121 and the first inner surface 11122 can be planar or curved. As an example, in the embodiment shown in FIG10, both the first inner surface 11122 and the first outer surface 11121 are planar, and the inner surface of the first region 1111 is coplanar with the first inner surface 11122.

[0152] The first protrusion 11111 is the portion of the first region 1111 that protrudes from the first outer surface 11121. The first protrusion 11111 can be of uniform thickness or of non-uniform thickness. The buffer member 50 may be located only partially between the first protrusion 11111 and the end plate 30, or the entire buffer member 50 may be located between the first protrusion 11111 and the end plate 30.

[0153] With a fixed thickness, the first region 1111 partially protrudes from the first outer surface 11121, which reduces the space occupied by the first region 1111 in the internal space of the housing 11, thus freeing up more space for the electrode assembly 2. The buffer member 50 is at least partially located between the first protrusion 11111 and the end plate 30. The buffer member 50 acts as a buffer between the first protrusion 11111 and the end plate 30, reducing the risk that the rigid contact between the end plate 30 and the first protrusion 11111 may affect the reinforcing effect of the first region 1111.

[0154] In some embodiments, referring to FIG10, a recess 501 is formed at a position corresponding to the first protrusion 11111 in the buffer 50, and the first protrusion 11111 is at least partially accommodated in the recess 501.

[0155] The recess 501 may be a groove provided on the side of the buffer member 50 away from the end plate 30 (shown in FIG. 9) along the first direction X. It may be that only a portion of the first protrusion 11111 is accommodated in the recess 501, or the entire first protrusion 11111 may be accommodated in the recess 501.

[0156] In this embodiment, the first protrusion 11111 is at least partially accommodated in the recess 501, so that at least part of the first protrusion 11111 is embedded in the buffer 50. This reduces the overall size of the end plate 30, the buffer 50, and the first battery cell 10a along the first direction X, making the structure of the end plate 30, the buffer 50, and the first battery cell 10a more compact, improving space utilization, and helping to improve the volumetric energy density of the battery device 100.

[0157] In some embodiments, along the first direction X, the maximum thickness of the buffer 50 is T, and the maximum thickness of the first protrusion 11111 is L1, where L1 < T.

[0158] The thickness direction of the buffer member 50 and the thickness direction of the first protrusion 11111 are both parallel to the first direction X. The buffer member 50 can be a structure of uniform thickness or a structure of non-uniform thickness. The thickness of the thickest part of the buffer member 50 is the maximum thickness of the buffer member 50, and the thickness of the thickest part of the first protrusion 11111 is the maximum thickness of the first protrusion 11111.

[0159] As an example, the buffer 50 has a non-uniform thickness structure. The thickness of the area where the recess 501 is provided in the buffer 50 is less than the thickness of other areas, and the thickness of the other areas is the maximum thickness of the buffer 50. Along the first direction X, the maximum distance between the surface of the first protrusion 11111 that is away from the first outer surface 11121 and the first outer surface 11121 is equal to the maximum thickness of the first protrusion 11111.

[0160] L1 / T < 1, and L1 / T can take any point value or a range between any two of the following: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95.

[0161] In this embodiment, L1 < T, even if the first protrusion 11111 is completely embedded in the buffer 50, a portion of the buffer 50 will be located between the end plate 30 and the first protrusion 11111, making it difficult for the end plate 30 and the first protrusion 11111 to make rigid contact.

[0162] In some embodiments, please refer to FIG11, which is a positional relationship diagram of the first wall 111 and the buffer member 50 provided in other embodiments of this application. Along the first direction X, the second region 1112 has a first inner surface 11122, the first inner surface 11122 is disposed opposite to the first outer surface 11121, and a portion of the first region 1111 protrudes from the first inner surface 11122.

[0163] The thickness of the portion of the first region 1111 protruding from the first outer surface 11121 may be greater than the thickness of the portion of the first region 1111 protruding from the first inner surface 11122, or the thickness of the portion of the first region 1111 protruding from the first outer surface 11121 may be equal to the thickness of the portion of the first region 1111 protruding from the first inner surface 11122, or the thickness of the portion of the first region 1111 protruding from the first outer surface 11121 may be less than the thickness of the portion of the first region 1111 protruding from the first inner surface 11122.

[0164] In this embodiment, the first region 1111 has both a portion protruding from the first outer surface 11121 and a portion protruding from the first outer surface 11121. With a fixed thickness, the thickness of the portion of the first region 1111 protruding from the first outer surface 11121 and the thickness of the portion of the first region 1111 protruding from the first inner surface 11122 are not too large, thus reducing the occupancy of the first region 1111 on the internal or external space of the housing 11.

[0165] In some embodiments, please continue to refer to FIG11. The first region 1111 also includes a second protrusion 11112 protruding from the first inner surface 11122. Along the first direction X, the maximum thickness of the first protrusion 11111 is L1, and the maximum thickness of the second protrusion 11112 is L2, where L1 > L2.

[0166] The second protrusion 11112 is the portion of the first region 1111 that protrudes from the first inner surface 11122. The second protrusion 11112 can be of uniform thickness or of non-uniform thickness. The thickness of the thickest part of the second protrusion 11112 is the maximum thickness of the second protrusion 11112. As an example, along the first direction X, the maximum distance between the surface of the second protrusion 11112 facing away from the first inner surface 11122 and the first inner surface 11122 is equal to the maximum thickness of the second protrusion 11112.

[0167] L1 / L2 > 1, and L1 / L2 can take any one of the following point values ​​or any range between two values: 1.1, 1.3, 1.5, 1.7, 1.9, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10.

[0168] In this embodiment, the first protrusion 11111 has a larger maximum thickness, while the second protrusion 11112 has a smaller maximum thickness. Given a fixed thickness in the first region 1111, the second protrusion 11112 reduces its occupancy of the internal space of the housing 11, freeing up more space for the electrode assembly 2 and thus increasing the volumetric energy density of the battery cell 10. In the embodiment where the buffer 50 has a recess 501, the first protrusion 11111, with its larger maximum thickness, can be accommodated within the recess 501, preventing an increase in the overall dimensions of the end plate 30, buffer 50, and battery cell 10 along the first direction X due to the larger maximum thickness of the first protrusion 11111 compared to the second protrusion 11112.

[0169] In some embodiments, 0.05mm ≤ L1 ≤ 1.2mm.

[0170] L1 can take any one of the following point values ​​or a range between any two: 0.05mm, 0.08mm, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm.

[0171] In some embodiments, 0.05mm ≤ L2 ≤ 1mm.

[0172] L2 can take any one of the following point values ​​or a range between any two: 0.05mm, 0.08mm, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm.

[0173] In some embodiments, please continue to refer to FIG9. Along the first direction X, the orthographic projection of the buffer 50 and the orthographic projection of the end plate 30 both cover the first area 1111.

[0174] In the projection plane perpendicular to the first direction X, the overlapping area of ​​the orthographic projection of the buffer 50, the orthographic projection of the first area 1111, and the orthographic projection of the end plate 30 is the orthographic projection of the first area 1111.

[0175] The buffer 50 can extend beyond the opposite ends of the first region 1111 along the second direction Z and extend beyond the opposite ends of the first region 1111 along the third direction Y, so that the orthogonal projection of the buffer 50 along the first direction X covers the first region 1111.

[0176] The end plate 30 can extend beyond the opposite ends of the first region 1111 along the second direction Z and extend beyond the opposite ends of the first region 1111 along the third direction Y, so that the orthographic projection of the end plate 30 along the first direction X covers the first region 1111.

[0177] Along the first direction X, the orthographic projection of the buffer 50 and the orthographic projection of the end plate 30 can cover part or all of the connecting portion 7, such that a part of the buffer 50 is located between the end plate 30 and the connecting portion 7 along the first direction X.

[0178] In this embodiment, along the first direction X, the orthographic projection of the buffer 50 and the orthographic projection of the end plate 30 both cover the first area 1111, increasing the area of ​​the portion of the buffer 50 located between the end plate 30 and the first area 1111, so as to play a better buffering role between the end plate 30 and the first area 1111.

[0179] In some embodiments, the first region 1111 is pressed against the end plate 30 by the buffer 50.

[0180] Along the first direction X, the buffer 50 maintains contact with both the first zone 1111 and the end plate 30. The first zone 1111 and the end plate 30 cooperate to compress the buffer 50, and the portion of the buffer 50 located between the first zone 1111 and the end plate 30 is in a compressed state.

[0181] In embodiments where the first region 1111 includes the first protrusion 11111, the first protrusion 11111 may be pressed against the end plate 30 by the buffer 50.

[0182] In this embodiment, the first region 1111 is pressed against the end plate 30 by the buffer 50, making the structure of the first region 1111, the buffer 50 and the end plate 30 more compact, which is beneficial to improving the volumetric energy density of the battery device 100.

[0183] In some embodiments, a portion of the buffer 50 is disposed between the second region 1112 and the end plate 30 along the first direction X.

[0184] In a projection plane perpendicular to the first direction X, the orthographic projections of the buffer 50, the second region 1112, and the end plate 30 have overlapping areas.

[0185] It is understood that the buffer 50 has a portion disposed between the first zone 1111 and the end plate 30, and the buffer 50 also has a portion disposed between the second zone 1112 and the end plate 30. The buffer 50 and the second zone 1112 can be in contact or separated; the buffer 50 and the end plate 30 can be in contact or separated.

[0186] In this embodiment, the buffer 50 acts as a buffer between the second zone 1112 and the end plate 30, reducing the risk that the end plate 30 and the second zone 1112 will make rigid contact and affect the reinforcement effect of the first zone 1111.

[0187] In some embodiments, along the first direction X, the orthographic projection of the buffer 50 and the orthographic projection of the end plate 30 both cover the second region 1112.

[0188] In the projection plane perpendicular to the first direction X, the overlapping area of ​​the orthographic projection of the buffer 50, the orthographic projection of the second area 1112, and the orthographic projection of the end plate 30 is the orthographic projection of the second area 1112.

[0189] The buffer 50 can extend beyond the opposite ends of the second region 1112 along the second direction Z and extend beyond the opposite ends of the second region 1112 along the third direction Y, so that the orthogonal projection of the buffer 50 along the first direction X covers the second region 1112.

[0190] The end plate 30 can extend beyond the opposite ends of the second region 1112 along the second direction Z and extend beyond the opposite ends of the second region 1112 along the third direction Y, so that the orthographic projection of the end plate 30 along the first direction X covers the second region 1112.

[0191] In this embodiment, along the first direction X, the orthographic projection of the buffer 50 and the orthographic projection of the end plate 30 both cover the second area 1112, increasing the area of ​​the portion of the buffer 50 located between the end plate 30 and the second area 1112, so as to play a better buffering role between the end plate 30 and the second area 1112.

[0192] In some embodiments, the second region 1112 is pressed against the end plate 30 by the buffer 50.

[0193] Along the first direction X, the buffer 50 maintains contact with both the second zone 1112 and the end plate 30. The second zone 1112 and the end plate 30 cooperate to compress the buffer 50, and the portion of the buffer 50 located between the second zone 1112 and the end plate 30 is in a compressed state.

[0194] In this embodiment, the second region 1112 is pressed against the end plate 30 by the buffer 50, making the structure of the second region 1112, the buffer 50 and the end plate 30 more compact, which is beneficial to improving the volumetric energy density of the battery device 100.

[0195] In some embodiments, the thermal conductivity of the buffer 50 is less than or equal to 0.06 W / (m·K).

[0196] The buffer 50 can be a heat insulation pad disposed between the end plate 30 and the first wall 111. The buffer 50 has both buffering and heat insulation functions.

[0197] The thermal conductivity of the buffer 50 is λ, where λ ≤ 0.06 W / (m·K). The unit W / (m·K) represents watts per meter Kelvin. λ can take any single value from 0.01 W / (m·K), 0.02 W / (m·K), 0.03 W / (m·K), 0.04 W / (m·K), 0.05 W / (m·K), 0.06 W / (m·K), or a range between any two.

[0198] In this embodiment, λ≤0.06W / (m·K) ensures that the buffer 50 has good heat insulation capabilities, thereby reducing the heat transfer between the first battery cell 10a and the end plate 30.

[0199] In some embodiments, the buffer 50 is a cushioning pad made of insulating material.

[0200] Insulating materials can be rubber, plastics, etc. Rubber can be nitrile rubber, silicone rubber, fluororubber, etc.; plastics can be polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), polycarbonate (PC), etc.

[0201] In this embodiment, the buffer 50 is a buffer pad made of insulating material, so that the insulating member 6 has both buffering and insulating functions, so as to achieve insulation isolation between the first zone 1111 and the end plate 30.

[0202] In some embodiments, please refer to Figures 12 and 13. Figure 12 is a partial view of the first battery cell 10a provided in some embodiments of this application; Figure 13 is a partial enlarged view of point D in Figure 12. The first wall 111 also includes a transition region 1113, which is connected to the end of the first region 1111 away from the second region 1112 along the second direction Z. The transition region 1113 is connected to the connecting portion 7, and the connection position of the transition region 1113 and the connecting portion 7 forms a connection interface 71. The connection interface 71 has a first position 711 that is closest to the first region 1111 along the second direction Z. The first position 711 is located at the end of the first region 1111 away from the second region 1112 along the second direction Z.

[0203] The transition zone 1113 may be the portion of the first wall 111 connecting the connecting portion 7 and the first zone 1111. The transition zone 1113 may be a structure of uniform thickness or a structure of non-uniform thickness. The thickness of the transition zone 1113 may be less than the thickness of the first zone 1111, and the thickness direction of the transition zone 1113 and the thickness direction of the first zone 1111 are both parallel to the first direction X. As an example, in the embodiment shown in Figures 12 and 13, the thickness of the transition zone 1113 gradually decreases along the direction from the second zone 1112 to the first zone 1111.

[0204] The hardness of the transition zone 1113 may be equal to or unequal to the hardness of the first zone 1111. The hardness of the transition zone 1113 may be equal to or unequal to the hardness of the connecting portion 7.

[0205] The connection interface 71 is formed at the connection position between the transition area 1113 and the connection part 7, and the transition area 1113 and the connection part 7 are separated at the connection interface 71. The connection interface 71 can be a plane or a curved surface.

[0206] The first zone 1111 and the transition zone 1113 are separated by the first interface W, which is a virtual plane. The first interface W passes through the first position 711 and is perpendicular to the second direction Z. The transition zone 1113 and the connecting part 7 are located above the first interface W, and the first zone 1111 is located below the first interface W.

[0207] In this embodiment, the transition area 1113 and the connecting part 7 are connected to form a connection interface 71, so that the transition area 1113 and the connecting part 7 have a sufficiently large contact area, which improves the firmness of the first wall 111 and the end cap 12 after welding.

[0208] In some embodiments, at least a portion of the connection interface 71 extends at an angle relative to the first direction X.

[0209] The connection interface 71 can extend at an angle relative to the first direction X as a whole, or it can extend at an angle relative to the first direction X in a partial manner. It is understood that the extension direction of the portion of the connection interface 71 that extends at an angle relative to the first direction X is not parallel to the first direction X.

[0210] After the end cap 12 and the first wall 111 are welded, the connecting portion 7 shrinks as it solidifies, generating tensile stress on the transition zone 1113. When the first wall 111 is subjected to the expansion force of the electrode assembly 2, it deforms, and the transition zone 1113 generates tensile stress on the connecting portion 7. Since the connecting interface 71 extends at least partially at an angle relative to the first direction X, the tensile stress generated by the connecting portion 7 due to shrinkage on the transition zone 1113 near the portion of the connecting interface 71 that extends at an angle relative to the first direction X (the direction of the tensile stress is approximately perpendicular to the portion of the connecting interface 71 that extends at an angle relative to the first direction X) is not in the same direction as the tensile stress generated by the transition zone 1113 due to deformation of the first wall 111 on the connecting portion 7 (the direction of the tensile stress is approximately parallel to the second direction Z). This reduces the risk of fatigue cracking in the area of ​​the transition zone 1113 near the connecting interface 71.

[0211] In some embodiments, please continue to refer to FIG13, the connection interface 71 includes a first interface 71a, which extends obliquely from a first position 711 toward the end cap 12. Along the first direction X, at least a portion of the transition region 1113 is located between the first interface 71a and the end cap 12.

[0212] It is understandable that the first interface 71a extends at an angle relative to the first direction X. The first interface 71a can be a plane or a curved surface.

[0213] The first position 711 is the lowest position of the first interface 71a (the position closest to the first area 1111). The first interface 71a extends obliquely from the first position 711 toward the end cover 12, that is, the first interface 71a extends obliquely upward from the first position 711 toward the end cover 12.

[0214] Along the first direction X, the transition region 1113 can be entirely located between the first interface 71a and the end cap 12, or only a portion of the transition region 1113 can be located between the first interface 71a and the end cap 12.

[0215] In this embodiment, at least a portion of the transition region 1113 is located between the first interface 71a and the end cap 12 along the first direction X. The connecting portion 7 protects the transition region 1113. When the first wall 111 is subjected to the expansion force of the electrode assembly 2, the deformation of the transition region 1113 during the force process is blocked by the connecting portion 7, which reduces the risk of fatigue cracking in the area of ​​the transition region 1113 near the first interface 71a.

[0216] In some embodiments, please continue to refer to FIG13, the first interface 71a is connected to the outer surface of the first region 1111 at the first position 711.

[0217] As an example, the first interface 71a intersects the outer surface of the first region 1111 at a first line, which extends along a third direction Y, and the location of the first line is the first position 711. The first interface 71a is connected to the inner surface of the transition region 1113 at a second position 712 along a second direction Z, and the second position 712 is farther away from the first region 1111 than the first position 711. The transition region 1113 is approximately triangular in shape.

[0218] In this embodiment, the first interface 71a is connected to the outer surface of the first region 1111 at the first position 711, so that the first region 1111 and the connecting part 7 are closer along the second direction Z, which further reduces the risk of fatigue cracking of the area of ​​the first wall 111 near the connecting part 7 due to the expansion of the electrode assembly 2.

[0219] In some embodiments, please refer to Figures 14 and 15. Figure 14 is a partial view of a first battery cell 10a provided in some embodiments of this application; Figure 15 is a partial enlarged view of point E in Figure 14. The connection interface 71 includes a second interface 71b, which extends obliquely from a first position 711 in a direction away from the end cap 12. Along the first direction X, at least a portion of the transition region 1113 is located on the side of the second interface 71b away from the end cap 12.

[0220] Understandably, the second interface 71b extends at an angle relative to the first direction X. The second interface 71b can be planar or curved. Along the first direction X, at least a portion of the connecting portion 7 is located between the second interface 71b and the end cap 12.

[0221] The first position 711 is the lowest position of the second interface 71b (the position closest to the first area 1111). The second interface 71b extends obliquely from the first position 711 in a direction away from the end cover 12, that is, the second interface 71b extends obliquely upward from the first position 711 in a direction away from the end cover 12.

[0222] Along the first direction X, the transition region 1113 can be entirely located on the side of the second interface 71b away from the end cover 12, or the transition region 1113 can be only partially located on the side of the second interface 71b away from the end cover 12.

[0223] In this embodiment, at least a portion of the transition region 1113 is located on the side of the second interface 71b away from the end cap 12 along the first direction X, so that the transition region 1113 restricts the connection portion 7 and reduces the risk of the connection portion 7 falling off.

[0224] In some embodiments, please continue to refer to FIG15, the second interface 71b is connected to the inner surface of the first region 1111 at the first position 711.

[0225] As an example, the second interface 71b intersects the inner surface of the first region 1111 at a second line, which extends along a third direction Y, and the location of the second line is the first position 711. The second interface 71b is connected to the outer surface of the transition region 1113 at a third position 713, along a second direction Z. The third position 713 is farther away from the first region 1111 than the first position 711. The transition region 1113 is approximately triangular in shape.

[0226] In this embodiment, the second interface 71b is connected to the inner surface of the first region 1111 at the first position 711, making the first region 1111 and the connecting part 7 closer along the first direction X, further reducing the risk of fatigue cracking of the area of ​​the first wall 111 near the connecting part 7 due to the expansion of the electrode assembly 2.

[0227] In some embodiments, please refer to Figures 16 and 17. Figure 16 is a partial view of the first battery cell 10a provided in some embodiments of this application; Figure 17 is a partial enlarged view at point F in Figure 16. The connection interface 71 includes a first interface 71a and a second interface 71b. The first interface 71a extends obliquely from the first position 711 toward the end cap 12, and the second interface 71b extends obliquely from the first position 711 toward the end cap 12. Along the first direction X, a portion of the transition region 1113 is located between the first interface 71a and the end cap 12, and another portion of the transition region 1113 is located on the side of the second interface 71b away from the end cap 12.

[0228] As an example, the first interface 71a is connected to the inner surface of the transition region 1113 at the second position 712, and the second interface 71b is connected to the outer surface of the transition region 1113 at the third position 713.

[0229] In some embodiments, the Vickers hardness of the transition region 1113 is less than the Vickers hardness of the second region 1112; and / or, the Vickers hardness of the transition region 1113 is less than the Vickers hardness of the connecting portion 7.

[0230] As an example, the Vickers hardness of the second zone 1112 is less than that of the connecting part 7.

[0231] If the Vickers hardness of the transition zone 1113 is less than that of the second zone 1112, the transition zone 1113, with its lower Vickers hardness, connects to the connecting portion 7. This alleviates the rigid tension between the first wall 111 and the connecting portion 7 when the first wall 111 deforms, reducing the risk of separation between the first wall 111 and the connecting portion 7. Conversely, if the Vickers hardness of the transition zone 1113 is less than that of the connecting portion 7, the transition zone 1113 is more prone to deformation than the connecting portion 7. This also alleviates the rigid tension between the first wall 111 and the connecting portion 7 when the first wall 111 deforms, reducing the risk of separation between the first wall 111 and the connecting portion 7.

[0232] In some embodiments, at least a portion of the Vickers hardness of the first region 1111 is less than the Vickers hardness of the second region 1112.

[0233] It can be that the Vickers hardness of the entire first zone 1111 is less than the Vickers hardness of the second zone 1112, or it can be that only a portion of the Vickers hardness of the first zone 1111 is less than the Vickers hardness of the second zone 1112.

[0234] As an example, the Vickers hardness of a portion of the first zone 1111 is less than that of the second zone 1112, the Vickers hardness of another portion of the first zone 1111 is equal to that of the second zone 1112, and the portion of the first zone 1111 with the same Vickers hardness as the second zone 1112 is directly connected to the second zone 1112.

[0235] When the second region 1112 deforms under the expansion force of the electrode assembly 2, the area in the first region 1111 with a smaller Vickers hardness than the second region 1112 can reduce the impact of the deformation of the second region 1112 on the area of ​​the first wall 111 near the connection part 7, thereby reducing the risk of fatigue cracking of the area of ​​the first wall 111 near the connection part 7 due to the expansion of the electrode assembly 2.

[0236] In some embodiments, please refer to Figures 18-22. Figure 18 is an isometric view of the housing 11 provided in some embodiments of this application; Figure 19 is an isometric view of the electrode assembly 2 provided in some embodiments of this application; Figure 20 is a structural schematic diagram of the electrode assembly 2 shown in Figure 19; Figure 21 is an isometric view of the electrode assembly 2 provided in other embodiments of this application; Figure 22 is a structural schematic diagram of the electrode assembly 2 shown in Figure 21. The electrode assembly 2 includes a positive electrode 22 and a negative electrode 23. At least a portion of the positive electrode 22 and at least a portion of the negative electrode 23 are stacked along a first direction X. The first wall 111 is the wall with the largest outer surface area in the housing 11.

[0237] It should be noted that the first wall 111 is the wall with the largest outer surface area in the shell 11, but this does not limit the shell 11 to having only one first wall 111. As an example, taking the shell 11 as a cuboid, the shell 11 may include two first walls 111 and two second walls 112. The two first walls 111 are arranged opposite each other along the first direction X, and the two second walls 112 are arranged opposite each other along the third direction Y. The outer surface area of ​​the first wall 111 is larger than the outer surface area of ​​the second wall 112.

[0238] Because at least a portion of the positive electrode 22 and at least a portion of the negative electrode 23 are stacked along the first direction X, the electrode assembly 2 expands significantly along the first direction X during cycling, making the first region 1111 of the first wall 111 more susceptible to compression from the end plate 30. In this embodiment, a buffer 50 is provided between the first region 1111 and the end plate 30, effectively reducing the risk of rigid contact between the end plate 30 and the first region 1111 during the expansion of the electrode assembly 2.

[0239] In some embodiments, please refer to Figures 19-22. The electrode assembly 2 has a flat region 25. The portion of the positive electrode 22 located in the flat region 25 and the portion of the negative electrode 23 located in the flat region 25 are stacked along the first direction X.

[0240] The flat region 25 is the flat portion of the electrode assembly 2. The portion of the positive electrode 22 located in the flat region 25 is approximately flat, and the portion of the negative electrode 23 located in the flat region 25 is also approximately flat. As an example, both the portions of the positive electrode 22 and the negative electrode 23 located in the flat region 25 are flat plate structures. If the electrode assembly 2 is a wound structure, it is a wound electrode assembly, and a portion of the electrode assembly 2 may be the flat region 25; if the electrode assembly 2 is a stacked structure, it is a stacked electrode assembly, and the entire electrode assembly 2 may be the flat region 25. The first direction X is the stacking direction of the portions of the positive electrode 22 and the negative electrode 23 located in the flat region 25.

[0241] As an example, the electrode assembly 2 may also include a separator 24, which is disposed between the positive electrode 22 and the negative electrode 23, and serves to separate the positive electrode 22 and the negative electrode 23. The portion of the positive electrode 22 located in the flat region 25, the portion of the negative electrode 23 located in the flat region 25, and the portion of the separator 24 located in the flat region 25 are stacked along the first direction X.

[0242] The first direction X is the stacking direction of the portion of the positive electrode 22 located in the flat region 25 and the portion of the negative electrode 23 located in the flat region 25. During cycling, the electrode assembly 2 expands more along the first direction X, and the first wall 111 is more affected by the expansion of the electrode assembly 2. Since the first region 1111 strengthens the area of ​​the first wall 111 near the connection portion 7, the risk of fatigue cracking of the first wall 111 near the connection portion 7 due to the expansion of the electrode assembly 2 is reduced.

[0243] In some embodiments, please continue to refer to Figures 19 and 20. The electrode assembly 2 is a wound structure. The electrode assembly 2 also has a corner region 26. The straight region 25 is provided with a corner region 26 at at least one end along the third direction Y. The first direction X, the second direction Z and the third direction Y are not coplanar and intersect each other.

[0244] The straight area 25 may have a corner area 26 at only one end along the third direction Y, or it may have corner areas 26 at both opposite ends along the third direction Y. The first direction X, the second direction Z, and the third direction Y are not coplanar, and any two of the first direction X, the second direction Z, and the third direction Y may be set at an acute angle, a right angle, or an obtuse angle.

[0245] As an example, the positive electrode 22, the separator 24, and the negative electrode 23 are stacked and wound to form a wound structure. The first direction X, the second direction Z, and the third direction Y are perpendicular to each other, and the straight region 25 has corner regions 26 at both ends along the third direction Y. The portions of the positive electrode 22, the negative electrode 23, and the separator 24 located in the corner regions 26 are in a bent state. The portion of the positive electrode 22 located in the corner region 26 can be at least partially arc-shaped, the portion of the negative electrode 23 located in the corner region 26 can be at least partially arc-shaped, and the portion of the separator 24 located in the corner region 26 can be at least partially arc-shaped.

[0246] For the wound electrode assembly, the flat region 25 expands more in the second direction Z. Since the first region 1111 strengthens the area of ​​the first wall 111 near the connection 7, it can effectively reduce the risk of fatigue cracking of the first wall 111 near the connection 7 due to the expansion of the electrode assembly 2.

[0247] In some embodiments, please continue to refer to Figures 21 and 22. The electrode assembly 2 is a stacked structure. The flat region 25 includes a plurality of positive electrode plates 22 and a plurality of negative electrode plates 23. The plurality of positive electrode plates 22 and the plurality of negative electrode plates 23 are stacked along the first direction X.

[0248] As an example, multiple positive electrode plates 22, multiple negative electrode plates 23, and multiple separators 24 are stacked along the first direction X to form a stacked structure. The positive electrode plates 22 and negative electrode plates 23 are completely located in the flat region 25, and separators 24 are provided between adjacent positive electrode plates 22 and negative electrode plates 23.

[0249] For stacked electrode assemblies, the expansion of electrode assembly 2 is greater in the stacking direction of positive electrode 22 and negative electrode 23. Since the first region 1111 strengthens the area of ​​the first wall 111 near the connection portion 7, the risk of fatigue cracking of the first wall 111 near the connection portion 7 due to the expansion of electrode assembly 2 can be effectively reduced.

[0250] This application provides an electrical device, including the battery device 100 provided in any of the previous embodiments.

[0251] This application embodiment also provides a battery device 100, including an end plate 30, a buffer member 50, and multiple rows of battery cells 10. There are two end plates 30, which are arranged opposite each other along a first direction X. The multiple rows of battery cells 10 are arranged along a third direction Y. Each row of battery cells 10 includes multiple battery cells 10, and these multiple battery cells 10 are stacked between the two end plates 30 along the first direction X. In each row of battery cells 10, the battery cell 10 closest to the end plate 30 is the first battery cell 10a. The first battery cell 10a includes a housing 11, an end cap 12, and an electrode assembly 2. The electrode assembly 2 is at least partially housed within the housing 11. The housing 11 has an opening at one end along the second direction Z, and the end cap 12 closes the opening. The housing 11 includes a first wall 111 facing the end plate 30 along the first direction X, and the end cap 12 is welded to the first wall 111 to form a connection portion 7. The first wall 111 includes a first region 1111 and a second region 1112 arranged along the second direction Z. The thickness of the first region 1111 is greater than the thickness of the second region 1112. Along the second direction Z, the first region 1111 is located between the second region 1112 and the connecting portion 7. Along the first direction X, a portion of the buffer member 50 is disposed between the first region 1111 and the end plate 30, and another portion of the buffer member 50 is disposed between the second region 1112 and the end plate 30. The thermal conductivity of the buffer member 50 is less than or equal to 0.06 W / (m·K), and the buffer member 50 is a buffer pad made of insulating material. The first direction X, the second direction Z, and the third direction Y are perpendicular to each other.

[0252] Along the first direction X, the orthographic projections of both the buffer member 50 and the end plate 30 cover the first region 1111, and the first region 1111 presses against the end plate 30 via the buffer member 50. Along the first direction X, the orthographic projections of both the buffer member 50 and the end plate 30 cover the second region 1112, and the second region 1112 presses against the end plate 30 via the buffer member 50. Along the first direction X, the second region 1112 has a first outer surface 11121 facing the exterior of the housing 11. The first region 1111 includes a first protrusion 11111 protruding from the first outer surface 11121. A portion of the buffer member 50 is located between the first protrusion 11111 and the end plate 30, and the first protrusion 11111 presses against the end plate 30 via the buffer member 50. A recess 501 is formed on the buffer member 50 at a position corresponding to the first protrusion 11111, and the first protrusion 11111 is accommodated within the recess 501.

[0253] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0254] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit this application. For those skilled in the art, this application can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A battery device, comprising: End plate; Multiple battery cells are disposed on the same side of the end plate along a first direction. The multiple battery cells are stacked along the first direction. The battery cell closest to the end plate among the multiple battery cells is the first battery cell. The first battery cell includes: The housing has an opening at at least one end along a second direction, the housing includes a first wall disposed facing the end plate along the first direction, the first wall includes a first region and a second region arranged along the second direction, the thickness of the first region is greater than the thickness of the second region, and the second direction intersects the first direction; An end cap is provided to close the opening. The end cap is welded to the first wall to form a connection. Along the second direction, the first region is located between the second region and the connection. The electrode assembly is at least partially housed within the housing; A buffer element is disposed, at least partially, along the first direction between the first area and the end plate.

2. The battery device as claimed in claim 1, wherein, Along the first direction, the second region has a first outer surface facing the outside of the housing, the first region including a first protrusion protruding from the first outer surface, and the buffer is at least partially located between the first protrusion and the end plate.

3. The battery device as claimed in claim 2, wherein, The buffer member forms a recess at a position corresponding to the first protrusion, and the first protrusion is at least partially accommodated within the recess.

4. The battery device as claimed in claim 2 or 3, wherein, Along the first direction, the maximum thickness of the buffer is T, and the maximum thickness of the first protrusion is L1, where L1 < T.

5. The battery device according to any one of claims 2-4, wherein, Along the first direction, the second region has a first inner surface, which is disposed opposite to the first outer surface, and a portion of the first region protrudes from the first inner surface.

6. The battery device as claimed in claim 5, wherein, The first region also includes a second protrusion protruding from the first inner surface. Along the first direction, the maximum thickness of the first protrusion is L1, and the maximum thickness of the second protrusion is L2, where L1 > L2.

7. The battery device as claimed in claim 6, wherein, 0.05mm≤L1≤1.2mm.

8. The battery device as claimed in claim 6 or 7, wherein, 0.05mm≤L2≤1mm.

9. The battery device according to any one of claims 1-8, wherein, Along the first direction, the orthographic projection of the buffer and the orthographic projection of the end plate both cover the first area.

10. The battery device according to any one of claims 1-9, wherein, The first area is pressed against the end plate by the buffer.

11. The battery device according to any one of claims 1-10, wherein, Along the first direction, a portion of the buffer is disposed between the second area and the end plate.

12. The battery device of claim 11, wherein, Along the first direction, the orthographic projection of the buffer and the orthographic projection of the end plate both cover the second area.

13. The battery device as claimed in claim 11 or 12, wherein, The second zone is pressed against the end plate by the buffer.

14. The battery device according to any one of claims 1-13, wherein, The thermal conductivity of the buffer is less than or equal to 0.06 W / (m·K).

15. The battery device according to any one of claims 1-14, wherein, The buffer is a cushioning pad made of insulating material.

16. The battery device according to any one of claims 1-15, wherein, The first wall further includes a transition zone connected to one end of the first zone away from the second zone along the second direction. The transition zone is connected to the connecting portion, and the connection position of the transition zone and the connecting portion forms a connection interface. The connection interface has a first position closest to the first zone along the second direction, and the first position is located at one end of the first zone away from the second zone along the second direction.

17. The battery device of claim 16, wherein, At least a portion of the connection interface extends at an angle relative to the first direction.

18. The battery device of claim 17, wherein, The connection interface includes a first interface that extends obliquely from the first position toward the end cap, and at least a portion of the transition area is located between the first interface and the end cap along the first direction.

19. The battery device of claim 18, wherein, The first interface is connected to the outer surface of the first area at the first position.

20. The battery device according to any one of claims 17-19, wherein, The connection interface includes a second interface that extends obliquely from the first position toward the end cap. Along the first direction, at least a portion of the transition area is located on the side of the second interface away from the end cap.

21. The battery device of claim 20, wherein, The second interface is connected to the inner surface of the first area at the first position.

22. The battery device according to any one of claims 16-21, wherein, The Vickers hardness of the transition zone is less than that of the second zone; and / or, the Vickers hardness of the transition zone is less than that of the connecting portion.

23. The battery device according to any one of claims 1-22, wherein, At least a portion of the Vickers hardness in the first region is less than that in the second region.

24. The battery device according to any one of claims 1-23, wherein, The electrode assembly includes a positive electrode and a negative electrode, at least a portion of the positive electrode and at least a portion of the negative electrode are stacked along the first direction, and the first wall is the wall with the largest outer surface area in the housing.

25. The battery device of claim 24, wherein, The electrode assembly has a flat region, and the portion of the positive electrode plate located in the flat region and the portion of the negative electrode plate located in the flat region are stacked along the first direction.

26. The battery device of claim 25, wherein, The electrode assembly has a wound structure and also has a corner region. The corner region is provided at least one end of the straight region along a third direction. The first direction, the second direction, and the third direction are not coplanar and intersect each other.

27. The battery device of claim 25, wherein, The electrode assembly is a stacked structure, and the flat region includes a plurality of positive electrode plates and a plurality of negative electrode plates, which are stacked along the first direction.

28. An electrical device comprising a battery device as claimed in any one of claims 1-27.

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