Battery cell, battery apparatus, and electric apparatus

Abstract

The present application relates to the technical field of batteries, and discloses a battery cell, a battery apparatus, and an electric apparatus. The battery cell comprises a housing and an electrode assembly; the housing comprises a housing body and an end cover, wherein the housing body is provided with an opening, the end cover covers the opening and is connected to the housing, and the housing and the end cover enclose to form an accommodating cavity; the electrode assembly is accommodated in the accommodating cavity; the housing has a first wall in a first direction, the first wall is connected to the end cover by means of a first weld seam, the end cover comprises an end cover body and a first buffer portion, and the first buffer portion is connected between the end cover body and the first wall. The technical solution provided in the present application can improve battery cell reliability.

Description

Battery cells, battery packs, and electrical devices Cross-reference to related applications

[0001] This application claims priority to Chinese patent application 202411487302.6, filed on October 23, 2024, entitled “Battery cell, battery device and power supply device”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery technology, and more specifically, to a battery cell, a battery device, and an electrical device. Background Technology

[0003] Battery cells are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools, etc.

[0004] In the development of battery cell technology, in addition to improving the performance of battery cells, their reliability is also a crucial consideration. Therefore, improving the reliability of battery cells is a continuous challenge in battery technology. Summary of the Invention

[0005] This application provides a battery cell, a battery device, and an electrical device to improve the reliability of the battery cell.

[0006] In a first aspect, embodiments of this application provide a battery cell, including a housing and an electrode assembly; the housing includes a casing and an end cap, the casing having an opening, the end cap covering the opening and connected to the casing via a first weld, the casing and the end cap forming a receiving cavity; the electrode assembly is received within the receiving cavity; wherein, the casing has a first wall in a first direction, the first wall being connected to the end cap, the end cap including an end cap body and a first buffer portion, the first buffer portion being connected between the end cap body and the first wall.

[0007] In the above technical solution, the end cap includes an end cap body and a first buffer portion, and the first buffer portion is connected between the end cap body and the first wall. When the first wall is subjected to the expansion force of the electrode assembly or external load, the first buffer portion can deform first to buffer the expansion force of the electrode assembly or external load, thereby reducing the risk of cracking at the first weld and improving the reliability of the battery cell.

[0008] In some embodiments, the electrode assembly includes a positive electrode and a negative electrode, the electrode assembly has a flat region, and the portion of the positive electrode located in the flat region and the portion of the negative electrode located in the flat region are stacked along the first direction.

[0009] In the above technical solution, since the flat area of ​​the electrode assembly is prone to expansion, and since the positive electrode plate and the negative electrode plate located in the flat area are stacked along the first direction, when the electrode assembly expands due to long-term use, the expansion force exerted by the electrode assembly on the first wall in the first direction is greater than the expansion force exerted by the electrode assembly on the housing in other directions. As a result, the risk of cracking at the first weld is greater than the risk of cracking at the connection between the other walls of the housing and the end cap. Connecting the first buffer part between the end cap body and the first wall allows the first buffer part to deform first, thereby buffering the expansion force of the electrode assembly, reducing the risk of cracking at the first weld, and thus improving the reliability of the battery cell.

[0010] In some embodiments, the electrode assembly includes a positive electrode and a negative electrode, the negative electrode including a negative active material, the negative active material including a silicon-based material.

[0011] In the above technical solution, placing silicon-based material on the negative electrode sheet can accommodate more metal ions, thereby effectively increasing the energy density of the battery cell. Furthermore, when the negative electrode active material of the negative electrode sheet is silicon-based, it also increases the deformation of the electrode assembly within the battery cell during use. Especially during charging, the embedding of metal ions into the silicon-based material of the negative electrode sheet causes the electrode assembly to expand in volume, thus increasing the pressure exerted by the electrode assembly on the first wall. Therefore, by connecting the first buffer portion between the end cap body and the first wall, when the first wall is subjected to the expansion force of the electrode assembly, the first buffer portion can deform first to buffer the expansion force or external load of the electrode assembly, thereby reducing the risk of cracking at the first weld and improving the reliability of the battery cell.

[0012] In some embodiments, the silicon-based material includes one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, silicon-containing alloy, or silicon-oxygen-carbon composite material.

[0013] In the above technical solution, each material is easy to process and meets design requirements. Specifically, adding silicon-based materials to the negative electrode active material of the negative electrode sheet can effectively improve the energy density of the battery cell because silicon-based materials can accommodate more metal ions than other elements; for example, the capacity of silicon-based materials is about ten times that of graphite. However, this also increases the deformation of the electrode assembly within the battery cell during use, especially during charging. The embedding of metal ions into the silicon-based material of the negative electrode sheet causes the electrode assembly to expand in volume, thus increasing the pressure of the electrode assembly on the first wall. Therefore, a first buffer portion is connected between the end cap body and the first wall. When the first wall is subjected to the expansion force of the electrode assembly, the first buffer portion can deform first to buffer the expansion force or external load of the electrode assembly, thereby reducing the risk of cracking at the first weld and improving the reliability of the battery cell.

[0014] In some embodiments, the electrode assembly includes a positive electrode and a negative electrode, the positive electrode including a positive active material, the positive active material including a nickel compound.

[0015] In the above technical solution, when the positive electrode active material of the positive electrode sheet includes a nickel-containing compound, on the one hand, it can effectively increase the energy density and cycle life of the battery cell; on the other hand, it will also increase the gas generated during the use of the battery cell, especially in the case of thermal runaway, the internal temperature of the battery cell will rise rapidly and a large amount of gas will be generated, thereby increasing the internal pressure on the first wall. Therefore, by connecting the first buffer part between the end cap body and the first wall, when the first wall is subjected to the expansion force of the electrode assembly, the first buffer part can deform first to buffer the expansion force or external load of the electrode assembly, thereby reducing the risk of cracking at the first weld and improving the reliability of the battery cell.

[0016] In some embodiments, the end cap body is a flat plate structure, and the first buffer portion is a bent structure.

[0017] In the above technical solution, the first buffer part is a bent structure, so that the dimension of the first buffer part in the bending direction is greater than its dimension in the first direction. Thus, when the first wall is subjected to the expansion force of the electrode assembly or external load, the first buffer part can be stretched and bent to allow the first buffer part to be relatively displaced in the first direction at the end connected to the end cap body and the end connected to the first wall, so as to buffer the expansion force of the electrode assembly or external load, thereby reducing the risk of cracking at the first weld and improving the reliability of the battery cell.

[0018] In some embodiments, the first buffer portion extends along a second direction, and the thickness direction of the end cap, the first direction, and the second direction are perpendicular to each other.

[0019] In the above technical solution, the first buffer portion extends along the second direction, thereby increasing the area of ​​the first buffer portion when the size of the first buffer portion in the first direction is constant. As a result, when the electrode assembly expands, the first buffer portion can generate greater deformation, which is beneficial to improve the buffering effect of the expansion force of the first buffer portion on the electrode assembly. This further reduces the force borne at the connection between the first wall and the first buffer portion, thereby reducing the risk of cracking at the first weld and improving the reliability of the battery cell.

[0020] In some embodiments, the dimension of the first buffer portion in the first direction is H1, and the length of the first buffer portion along its bending direction is H2, satisfying 1.05≤H2 / H1≤5.

[0021] In the above technical solution, when H2 / H1≥1.05, the dimension of the first buffer part in its bending direction is greater than its dimension in the first direction, so that when the first wall is subjected to the expansion force of the electrode assembly or external load, the relative displacement of the two ends of the first buffer part in the first direction has a large range, thereby reducing the risk of cracking at the first weld and improving the reliability of the battery cell. When H2 / H1≤5, the dimension of the first buffer part in its bending direction can be reduced, thereby reducing the dimension of the first buffer part in the thickness direction of the end cap, thereby reducing the space occupied by the end cap in its thickness direction, thereby reducing the space occupied by the battery cell in the thickness direction, and thus increasing the energy density of the battery cell without changing the volume of the electrode assembly. Therefore, when 1.05≤H2 / H1≤5, the battery cell with the first buffer part can reduce the risk of cracking at the first weld, thereby improving the reliability of the battery cell and increasing the energy density of the battery cell.

[0022] In some embodiments, 1.1 ≤ H2 / H1 ≤ 2.

[0023] In the above technical solution, when H2 / H1≥1.1, the dimension of the first buffer part in its bending direction is further larger than its dimension in the first direction, so that when the first wall is subjected to the expansion force of the electrode assembly or external load, the relative displacement of the two ends of the first buffer part in the first direction has a larger range, thereby further reducing the risk of cracking at the first weld and further improving the reliability of the battery cell. When H2 / H1≤2, the dimension of the first buffer part in its bending direction is further reduced, thereby further reducing the dimension of the first buffer part in the thickness direction of the end cap, thereby reducing the space occupied by the end cap in its thickness direction, thereby further reducing the space occupied by the battery cell in the thickness direction, and thus increasing the energy density of the battery cell without changing the volume of the electrode assembly. Therefore, when 1.1≤H2 / H1≤2, the battery cell with the first buffer part can further reduce the risk of cracking at the first weld, thereby improving the reliability of the battery cell, and at the same time, can further improve the energy density of the battery cell.

[0024] In some embodiments, 0.5mm ≤ H1 ≤ 40mm.

[0025] In the above technical solution, when H1≥0.5mm, the first buffer portion can have a certain size in the first direction, which facilitates the machining of the first buffer portion by external processing instruments such as stamping devices; when H1≤40mm, with the size of the end cap in the first direction being fixed, H1≤40mm can make the end cap body have sufficient size in the first direction, thereby improving the strength of the end cap body, thus providing a more stable working environment for other structural components of the battery cell set on the end cap body, thereby improving the reliability of the battery cell; therefore, when 0.5mm≤H1≤40mm, the battery cell with the first buffer portion can facilitate the machining of the first buffer portion by external processing instruments, and at the same time can provide a more stable working environment for other structural components of the battery cell set on the end cap body, thereby improving the reliability of the battery cell.

[0026] In some embodiments, 1mm ≤ H2 ≤ 40mm.

[0027] In the above technical solution, when H2≥1mm, the first buffer portion has a certain size in its bending direction, so that when the first wall is subjected to the expansion force of the electrode assembly or external load, the two ends of the first buffer portion can be relatively displaced in the first direction, thereby reducing the risk of cracking at the first weld and improving the reliability of the battery cell. When H2≤40mm, the size of the first buffer portion in its bending direction can be reduced, and further the size of the first buffer portion in the thickness direction of the end cap can be reduced, thereby reducing the space occupied by the end cap in its thickness direction, and further reducing the space occupied by the battery cell in the thickness direction, thereby increasing the energy density of the battery cell without changing the volume of the electrode assembly. Therefore, when 1mm≤H2≤40mm, the risk of cracking at the first weld can be reduced, thereby improving the reliability of the battery cell and increasing the energy density of the battery cell.

[0028] In some embodiments, the maximum thickness of the end cap body is T1, and the thickness of the first buffer portion is T2, satisfying 0.1≤T2 / T1≤0.9.

[0029] In the above technical solution, when T2 / T1≥0.1, the first buffer portion can have a certain thickness relative to the first wall, thereby reducing the thickness difference between the end cover body and the first buffer portion, and thus reducing the stress concentration at the transition between the end cover body and the first buffer portion, thereby reducing the risk of cracking of the cover body and the first buffer portion; when T2 / T1≤0.9, the thickness of the first buffer portion can be less than the thickness of the end cover body, thereby making the first buffer portion more prone to deformation relative to the end cover body, and thus, compared with the battery cell without the first buffer portion, the battery cell can reduce the risk of cracking at the first weld, thereby improving the reliability of the battery cell; therefore, when 0.1≤T2 / T1≤0.9, the battery cell with the first buffer portion can reduce the stress concentration at the transition between the end cover body and the first buffer portion, thereby reducing the risk of cracking of the cover body and the first buffer portion, and can also reduce the risk of cracking at the first weld.

[0030] In some embodiments, 0.1mm ≤ T2 ≤ 2.5mm.

[0031] In the above technical solution, when T2≥0.1mm, the first buffer portion has a certain thickness, which facilitates the processing of the first buffer portion, reduces the processing difficulty of the first buffer portion, and thus improves the yield of the battery cell with the first buffer portion. When T2≤2.5mm, the structural strength of the first buffer portion is lower. When the first wall is subjected to the expansion force of the electrode assembly, the first buffer portion can deform more easily, thereby reducing the force borne by the first weld and thus reducing the risk of cracking at the first weld. Therefore, when 0.1mm≤T2≤2.5mm, the yield of the battery cell with the first buffer portion can be improved, and the risk of cracking at the first weld can be further reduced.

[0032] In some embodiments, 0.3mm ≤ T1 ≤ 5mm.

[0033] In the above technical solution, when T1≥0.3mm, the end cap body can have a certain structural strength, thereby providing a more stable working environment for other structural components of the battery cell set on the end cap body, thus improving the reliability of the battery cell; when T1≤5mm, the size of the end cap body in its thickness direction can be reduced, thereby increasing the volume of the internal space of the shell with a fixed shell volume, so that the space can accommodate a larger volume of electrode components, increasing the energy density of the battery cell; therefore, when 0.3mm≤T1≤5mm, the reliability of the battery cell with the end cap body can be improved, and the energy density of the battery cell can be increased at the same time.

[0034] In some embodiments, the end cap is welded to the first wall to form a first weld portion.

[0035] In the above technical solution, the end cap and the first wall are connected by welding to form the first welded part, which can effectively improve the connection between the end cap and the first wall and reduce the risk of the end cap and the first wall falling off each other during use, thereby improving the reliability of the battery cell.

[0036] In some embodiments, the distance between the first buffer portion and the first weld portion in the first direction is H3, satisfying 0.5mm≤H3≤6mm.

[0037] In the above technical solution, when H3≥0.5mm, the first buffer part can be a certain distance from the first welding part in the first direction, thereby reducing the risk of the first buffer part failing due to the inflow of welding material into the first buffer part when welding the end cap and the first wall; when H3≤6mm, the distance between the first buffer part and the first wall is small, and when the first wall is subjected to the expansion force of the electrode assembly, it can be better transmitted to the first buffer part, so as to deform the first buffer part, thereby reducing the magnitude of the force borne by the first welding part and reducing the risk of cracking of the first welding part; therefore, when 0.5mm≤H3≤6mm, the risk of the first buffer part failing due to the inflow of welding material into the first buffer part can be reduced, and the force can be better transmitted to the first buffer part, so as to deform the first buffer part, thereby reducing the magnitude of the force borne by the first welding part and reducing the risk of cracking of the first welding part.

[0038] In some embodiments, 1mm ≤ H3 ≤ 4mm.

[0039] In the above technical solution, when H3≥1mm, the first buffer portion can be a certain distance from the first welding portion in the first direction, thereby further reducing the risk of the first buffer portion's buffering capacity failing due to the inflow of welding material into the first buffer portion when welding the end cap and the first wall; when H3≤4mm, the distance between the first buffer portion and the first wall is small, and when the first wall is subjected to the expansion force of the electrode assembly, it can be better transmitted to the first buffer portion, so as to deform the first buffer portion, thereby further reducing the magnitude of the force borne by the first welding portion, and thus further reducing the risk of the first welding portion cracking; therefore, when 1mm≤H3≤4mm, the risk of the first buffer portion's buffering capacity failing due to the inflow of welding material into the first buffer portion can be further reduced, and at the same time, it can be better transmitted to the first buffer portion, so as to deform the first buffer portion, thereby further reducing the magnitude of the force borne by the first welding portion, and thus further reducing the risk of the first welding portion cracking.

[0040] In some embodiments, the end cap body and the first buffer portion are integrally formed.

[0041] In the above technical solution, the end cap body and the first buffer part are integrally formed, which is beneficial to improving the connection strength between the end cap body and the first buffer part, and also helps to simplify the manufacturing process of the end cap.

[0042] In some embodiments, the housing has a second wall in a first direction, the second wall being disposed opposite to the first wall, and the second wall being connected to the end cap via a second weld; the end cap further includes a second buffer portion, the second buffer portion being connected between the end cap body and the second wall.

[0043] In the above technical solution, the end cap also includes a second buffer portion, which is connected between the end cap body and the second wall. When the second wall is subjected to the expansion force of the electrode assembly or external load, the second buffer portion can deform first to buffer the expansion force of the electrode assembly or external load, thereby reducing the risk of cracking at the second weld and improving the reliability of the battery cell.

[0044] In some embodiments, the housing has a third wall and a fourth wall disposed opposite to each other in a second direction. The third wall is connected to the end cap by a third weld, and the fourth wall is connected to the end cap by a fourth weld. The thickness direction of the end cap, the first direction, and the second direction are perpendicular to each other. The end cap further includes a third buffer portion and a fourth buffer portion. The third buffer portion is connected between the end cap body and the third wall, and the fourth buffer portion is connected between the end cap body and the fourth wall.

[0045] In the above technical solution, the end cap further includes a third buffer portion and a fourth buffer portion. The third buffer portion is connected between the end cap body and the third wall, and the fourth buffer portion is connected between the end cap body and the fourth wall. When the third wall is subjected to the expansion force of the electrode assembly or external load, the third buffer portion can deform first to buffer the expansion force of the electrode assembly or external load, thereby reducing the risk of cracking at the connection between the end cap and the third wall. When the fourth wall is subjected to the expansion force of the electrode assembly or external load, the fourth buffer portion can deform first to buffer the expansion force of the electrode assembly or external load, thereby reducing the risk of cracking at the connection between the end cap and the fourth wall, thereby improving the reliability of the battery cell.

[0046] In some embodiments, the first buffer section, the third buffer section, the second buffer section, and the fourth buffer section are connected end to end in sequence.

[0047] In the above technical solution, the first buffer section, the third buffer section, the second buffer section, and the fourth buffer section are connected end to end in sequence. So when the junction of the first wall, the third wall, the second wall, and the fourth wall is subjected to the expansion force of the electrode assembly, the junction of the first buffer section, the third buffer section, the second buffer section, and the fourth buffer section can deform first to buffer the expansion force of the electrode assembly or the external load, thereby reducing the risk of cracking at the junction of the end cap and the fourth wall at the junction of the first buffer section, the third buffer section, the second buffer section, and the fourth buffer section, and thus improving the reliability of the battery cell.

[0048] In some embodiments, the housing is made of aluminum or an aluminum alloy.

[0049] In the above technical solution, each material is easy to process and meets design requirements. Specifically, aluminum and aluminum alloys have good corrosion resistance and make the outer shell easily deformable. On the one hand, this provides an expandable space for the electrode assembly to accommodate its expansion, which helps to improve the service life of the battery cell. On the other hand, in this case, the first buffer part is connected between the end cap body and the first wall. When the first wall is subjected to the expansion force of the electrode assembly, the first buffer part can deform first to buffer the expansion force or external load of the electrode assembly, thereby reducing the risk of cracking at the first weld and improving the reliability of the battery cell.

[0050] Secondly, embodiments of this application also provide a battery device, including the aforementioned battery cell, wherein the battery cell is used to provide electrical energy.

[0051] Thirdly, embodiments of this application also provide an electrical device, including the aforementioned battery cell or battery, wherein the battery cell is used to provide electrical energy.

[0052] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0053] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0054] Figure 1 is a structural schematic diagram of a vehicle provided in some embodiments of this application;

[0055] Figure 2 is an exploded view of the structure of a battery device provided in some embodiments of this application;

[0056] Figure 3 is an exploded view of the structure of a battery cell provided in some embodiments of this application;

[0057] Figure 4 is a cross-sectional view of the housing provided in some embodiments of this application;

[0058] Figure 5 is a schematic diagram of an electrode assembly provided in some embodiments of this application;

[0059] Figure 6 is a schematic diagram of another electrode assembly provided in some embodiments of this application;

[0060] Figure 7 is a magnified view of part A in Figure 4;

[0061] Figure 8 is a cross-sectional view of a second type of first buffer section provided in some embodiments of this application;

[0062] Figure 9 is a cross-sectional view of a third type of first buffer section provided in some embodiments of this application;

[0063] Figure 10 is a cross-sectional view of a fourth type of first buffer section provided in some embodiments of this application;

[0064] Figure 11 is a schematic diagram of the structure of a battery cell provided in some embodiments of this application;

[0065] Figure 12 is a schematic diagram of the structure of the first buffer section after bending according to some embodiments of this application;

[0066] Figure 13 is a schematic diagram of the structure of the first buffer section before bending according to some embodiments of this application;

[0067] Figure 14 is a cross-sectional view of another housing provided in some embodiments of this application;

[0068] Figure 15 is a schematic diagram of another battery cell provided in some embodiments of this application;

[0069] The accompanying drawings are not drawn to scale.

[0070] Marking Explanation: 1000-Vehicle; 100-Battery Unit; 200-Controller; 300-Motor; 10-Box; 11-First Box Body; 12-Second Box Body; 20-Battery Cell; 21-Outer Shell; 211-Shell; 211A-First Wall; 211B-Second Wall; 211C-Third Wall; 211D-Fourth Wall; 212-End Cap; 2121-End Cap Body; 2122-First Buffer Section; 2123-Second Buffer Section; 2124-Third Buffer Section; 2125-Fourth Buffer Section; 2126-First Welding Section; 22-Electrode Assembly; 221-Taper; 222-Main Body; 223-Positive Electrode; 224-Negative Electrode; 22A-Straight Area; 22B-Bending Area; 23-Electrode Terminal; 24-Adapter; X-First Direction; Y-Second Direction; Z-Thickness Direction. Detailed Implementation

[0071] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of this application by way of example, but should not be used to limit the scope of this application, that is, this application is not limited to the described embodiments.

[0072] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein 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 specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0073] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly indicating the number, specific order, or primary and secondary relationship of the indicated technical features.

[0074] In this document, the term "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 throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0075] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces), unless otherwise explicitly specified.

[0076] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0077] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0078] In this application, "multiple" refers to two or more (including two), and similarly, "multiple groups" refers to two or more (including two), and "multiple pieces" refers to two or more (including two).

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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 made of stainless steel, copper, aluminum, carbon electrodes, carbon, nickel, or titanium with a silver-plated surface. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector 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.).

[0085] 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 for battery cells may also be used.

[0086] In some embodiments, the negative electrode can be a negative electrode sheet, and the negative electrode sheet can include a negative current collector.

[0087] As an example, the negative 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, copper, aluminum, carbon electrode, carbon, nickel, or titanium, etc.

[0088] In some embodiments, 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.

[0089] 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 for battery cells may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0090] In some embodiments, the diaphragm is a separator membrane. This application does not impose any particular limitation on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0091] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. The separator can be a separate component located between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes.

[0092] In some embodiments, the membrane 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.

[0093] In some embodiments, the electrode assembly is a wound structure. The positive electrode and the negative electrode are wound into a wound structure.

[0094] In some implementations, the electrode assembly is a stacked structure.

[0095] As an example, multiple positive and negative electrode plates can be set, and multiple positive and multiple negative electrode plates can be stacked alternately.

[0096] 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.

[0097] As an example, both the positive and negative electrode sheets are folded to form multiple stacked folded segments.

[0098] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0099] As an example, the separator can be continuously arranged between any adjacent positive or negative electrode plates by folding or rolling.

[0100] In some embodiments, the electrode assembly can be cylindrical, flat, or polygonal, etc.

[0101] 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.

[0102] 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 batteries, such as hexagonal prismatic batteries.

[0103] The battery mentioned in the embodiments of this application refers to a single physical module comprising one or more battery cells to provide higher voltage and capacity.

[0104] In some embodiments, the battery device can be a battery module, and when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0105] In some embodiments, the battery device may be a battery pack, which includes a housing and individual battery cells, with the individual battery cells or battery modules housed within the housing.

[0106] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0107] In some embodiments, the battery device may be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0108] Battery devices possess outstanding advantages such as high energy density, low environmental pollution, high power density, long service life, wide applicability, and low self-discharge coefficient, making them an important component of today's new energy development. The development of battery technology must simultaneously consider multiple design factors, such as performance parameters like energy density, cycle life, discharge capacity, and charge / discharge rate. Furthermore, the reliability of the battery device must also be taken into account.

[0109] A battery cell typically consists of a housing and end caps. During battery cell manufacturing, the electrode assembly is usually installed into the housing, and then the end caps are attached to the housing. The end caps are usually connected to the housing using processes such as welding. The connection between the end cap and the housing is usually a relatively weak structure in the housing. However, during battery cell operation, the electrode assembly expands due to lithium plating and other factors, compressing the walls of the housing and exerting an expansion force on the housing walls. As the electrode assembly expands, the expansion force exerted on the housing walls gradually increases, eventually causing cracks at the connection between the battery cell's housing and the end caps, thus severely affecting the reliability of the battery cell.

[0110] Based on the above considerations, in order to withstand the expansion force at the connection between the casing and the end cap and reduce the risk of cracking at the connection, this application provides a battery cell, including a casing and an electrode assembly; the casing includes a housing and an end cap, the housing has an opening, the end cap closes to the opening and is connected to the housing, the housing and the end cap enclose a receiving cavity; the electrode assembly is received within the receiving cavity; wherein, the housing has a first wall in a first direction, the first wall is connected to the end cap by a first weld, the end cap includes an end cap body and a first buffer portion, the first buffer portion is connected between the end cap body and the first wall.

[0111] In this type of battery cell, the end cap includes an end cap body and a first buffer portion, which is connected between the end cap body and the first wall. When the first wall is subjected to the expansion force of the electrode assembly or external load, the first buffer portion can deform first to buffer the expansion force of the electrode assembly or external load, thereby reducing the risk of cracking at the first weld and improving the reliability of the battery cell.

[0112] 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.

[0113] For ease of explanation, the following embodiments will be described using a vehicle as an example of an electrical device according to an embodiment of this application.

[0114] Please refer to Figure 1, which is a structural schematic diagram of a vehicle 1000 provided in some embodiments of this application. The vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery device 100 is installed inside the vehicle 1000. The battery device 100 can 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, it can serve as the vehicle's operating power source or general power source. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 controls the battery device 100 to supply power to the motor 300, for example, to meet the power needs of the vehicle 1000 during startup, navigation, and driving.

[0115] In some embodiments of this application, the battery device 100 can not only serve as the operating power or 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.

[0116] Please refer to Figure 2, which is an exploded view of the structure of a battery device 100 provided in some embodiments of this application. The battery device 100 includes a housing 10 and battery cells 20, the battery cells 20 being housed within the housing 10.

[0117] The housing 10 provides assembly space for the battery cell 20, and can adopt various structures. In some embodiments, the housing 10 may include a first housing body 11 and a second housing body 12, which overlap each other, and together define an assembly space for accommodating the battery cell 20. The second housing body 12 may be a hollow structure open at one end, and the first housing body 11 may be a plate-like structure, with the first housing body 11 covering the open side of the second housing body 12 so that the first housing body 11 and the second housing body 12 together define the assembly space; alternatively, the first housing body 11 and the second housing body 12 may both be hollow structures open on one side, with the open side of the first housing body 11 covering the open side of the second housing body 12.

[0118] Of course, the box 10 formed by the first box body 11 and the second box body 12 can be of various shapes, such as a cylinder, a cuboid, or a cube. For example, in Figure 2, the shape of the box 10 is a cuboid.

[0119] In the battery device 100, there can be one or more battery cells 20 disposed within the housing 10. When there are multiple battery cells 20 disposed within the housing 10, they can be connected in series, in parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells 20 are connected in both series and parallel configurations. Multiple battery cells 20 can be directly connected in series, in parallel, or in a mixed configuration, and then the entire assembly of the multiple battery cells 20 is housed within the housing 10. Alternatively, the battery device 100 can also consist of multiple battery cells 20 first connected in series, in parallel, or in a mixed configuration to form a battery module, and then multiple battery modules are connected in series, in parallel, or in a mixed configuration to form a whole, which is then housed within the housing 10.

[0120] In some embodiments, the battery device 100 may also include other structures. For example, the battery device 100 may also include a busbar for connecting multiple battery cells 20 to achieve electrical connection between the multiple battery cells 20.

[0121] Each battery cell 20 can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited to these. The battery cell 20 can be in the form of a cuboid, cylinder, prism, or other shapes. For example, in Figure 3, the battery cell 20 has a cuboid structure.

[0122] According to some embodiments of this application, please refer to Figures 3 and 4. Figure 3 is an exploded view of the structure of a battery cell 20 provided in some embodiments of this application, and Figure 4 is a cross-sectional view of a housing 21 provided in some embodiments of this application. This application provides a battery cell 20, including a housing 21 and an electrode assembly 22. The housing 21 includes a shell 211 and an end cap 212. The shell 211 has an opening, and the end cap 212 covers the opening and is connected to the shell 211. The shell 211 and the end cap 212 enclose a receiving cavity. The electrode assembly 22 is received within the receiving cavity. The shell 211 has a first wall 211A in a first direction X. The first wall 211A is connected to the end cap 212 via a first weld. The end cap 212 includes an end cap body 2121 and a first buffer portion 2122, which is connected between the end cap body 2121 and the first wall 211A.

[0123] The housing 21 is a component for accommodating the electrode assembly 22. The housing 21 can also be used to accommodate an electrolyte, such as an electrolyte solution. In some embodiments, a receiving cavity is formed inside the housing 21 for accommodating the electrode assembly 22.

[0124] In some embodiments, the material of the housing 21 can be metal or a combination of metal and non-metal. For example, the housing 21 can be made of metal, such as aluminum, copper, iron, steel, or aluminum alloy; or, for example, some parts of the housing 21 can be made of metal, while the rest can be made of non-metal. For instance, the end cap 212 of the housing 21 can be made of metal, while other parts of the housing 21 can be made of non-metallic materials. The housing 21 can be adapted to the shape of the electrode assembly 22. For example, in FIG. 3, the electrode assembly 22 has a cuboid structure, so a cuboid housing 21 can be selected.

[0125] The housing 211 is a component for housing the electrode assembly 22. Exemplarily, the housing 211 may be a cuboid, a cylinder, or an elliptical cylinder.

[0126] End cap 212 is a component that covers the opening of housing 211 to isolate the internal environment of battery cell 20 from the external environment.

[0127] Understandably, the shape of the end cap 212 can be adapted to the shape of the housing 211. For example, if the housing 211 is a cuboid structure, the end cap 212 can be a rectangular plate structure adapted to the housing 211. The end cap 212 can also be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, etc. The material of the end cap 212 can be the same as or different from the material of the housing 211.

[0128] For example, the housing 21 includes a housing 211 and an end cap 212. One end of the housing 211 has an opening through which the electrode assembly 22 can be placed inside the housing 211. The housing 211 may be made of a metallic material, such as aluminum, aluminum alloy, or nickel-plated steel.

[0129] In some embodiments, the end cap 212 may be connected to the housing 211 by welding, bonding, snap-fitting or other connection methods.

[0130] The outer casing 21 may be provided with two electrode terminals 23. One of the two electrode terminals 23 is a positive electrode terminal and the other is a negative electrode terminal. Both electrode terminals 23 may be provided on the end cap 212, or both may be provided on the casing 211, or one may be provided on the end cap 212 and the other on the casing 211.

[0131] In some embodiments, both electrode terminals 23 are insulatedly mounted on the end cap 212, and the two electrode terminals 23 are respectively used for electrical connection with the positive and negative terminals of the electrode assembly 22. This allows current to flow into the electrode assembly 22 through one electrode terminal 23 and out of the electrode assembly 22 through the other electrode terminal 23.

[0132] Electrode assembly 22 is a component in the battery cell 20 where electrochemical reactions occur. The structure of electrode assembly 22 can be varied; exemplarily, electrode assembly 22 can be a wound structure formed by winding a positive electrode 223, a separator, and a negative electrode 224. Exemplarily, the separator is a separator membrane, and the main material of the separator membrane can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride.

[0133] The first direction X can be parallel to the width direction of the battery cell 20.

[0134] For example, referring to FIG3, the housing 21 may accommodate one electrode assembly 22 or multiple electrode assemblies 22, which are stacked along the second direction Y.

[0135] In some embodiments, referring to FIG3, the electrode assembly 22 includes a body 222 and two tabs 221. The battery cell 20 also includes two adapters 24. One adapter 24 is used to electrically connect one tab 221 to one electrode terminal 23. The other adapter 24 is used to electrically connect another tab 221 to another electrode terminal 23.

[0136] The main body 222 is the area where the electrode assembly 22 undergoes a chemical reaction within the battery cell 20. The main body 222 is a structure formed by winding together the area of ​​the positive electrode 223 coated with a positive active material layer, the separator, and the area of ​​the negative electrode 224 coated with a negative active material layer. It mainly works by moving metal ions between the positive electrode 223 and the negative electrode 224 with opposite polarities.

[0137] The two tabs are the parts of the electrode assembly 22 used to guide current into the main body 222 and out of the main body 222, respectively.

[0138] The first wall 211A is a wall portion of the housing 211 in the first direction X, and the first wall 211A is adjacent to the end cap 212. For example, the first wall 211A and other walls of the housing 211 surround the edge of the end cap 212.

[0139] The end cap 212 includes an end cap body 2121 and a first buffer portion 2122. Optionally, the end cap body 2121 and the first buffer portion 2122 can be integrally formed, except that the corresponding structure and shape are processed at the corresponding position of the first buffer portion 2122. Of course, the end cap body 2121 and the first buffer portion 2122 can also be formed separately and then connected together.

[0140] Understandably, when the first wall 211A is subjected to the expansion force of the electrode assembly 22 or external load, the first buffer portion 2122 is more likely to deform than the end cap body 2121. The first buffer portion 2122 can deform first to buffer the expansion force of the electrode assembly 22 or external load, thereby reducing the risk of cracking at the first weld and improving the reliability of the battery cell 20.

[0141] The end cap body 2121 can be a part of the end cap 212 used for installing and setting the structural components of the battery cell 20. For example, the electrode terminal 23 and the explosion-proof valve are all provided on the end cap body 2121.

[0142] The first buffer portion 2122 is the portion of the end cap 212 that deforms when the load is transmitted from the first wall 211A to the connection of the end cap 212. For example, the deformation can be elastic deformation or plastic deformation, and the deformation generated by the first buffer portion 2122 can be bending deformation or tensile deformation, etc.

[0143] The first buffer portion 2122 may be curved, recessed, or protruding, so that the first buffer portion 2122 can deform under the action of external force; or, the first buffer portion 2122 may be made of a flexible material such as a metal material or a non-metal material that is easy to stretch, so that it can deform under the action of external force.

[0144] In the embodiment where the electrode assembly 22 is electrically connected to the electrode terminal 23 disposed on the end cover 212 via the adapter 24 of the tab 221, there is a gap between the body 222 of the electrode assembly 22 and the end cover 212, thereby reducing the risk that the deformation of the first buffer part 2122 will compress the body 222 of the electrode assembly 22, causing the electrode assembly 22 to undergo more severe lithium plating and expansion, and thus improving the reliability of the battery cell 20.

[0145] In this embodiment, the end cap 212 includes an end cap body 2121 and a first buffer portion 2122, and the first buffer portion 2122 is connected between the end cap body 2121 and the first wall 211A. When the first wall 211A is subjected to the expansion force of the electrode assembly 22 or an external load, the first buffer portion 2122 can deform first to buffer the expansion force of the electrode assembly 22 or the external load, thereby reducing the risk of cracking at the first weld and improving the reliability of the battery cell 20.

[0146] According to some embodiments of this application, please refer to Figures 3 and 4, and further refer to Figures 5 and 6. Figures 5 and 6 are schematic diagrams of the structures of two electrode assemblies 22 provided in some embodiments of this application. The electrode assembly 22 includes a positive electrode 223 and a negative electrode 224. The electrode assembly 22 has a flat region 22A. The portions of the positive electrode 223 and the negative electrode 224 located in the flat region 22A are stacked along a first direction X.

[0147] The positive electrode 223 may include a positive current collector and a positive active material disposed on at least one surface of the positive current collector. As an example, the positive current collector has two surfaces opposite each other in its own thickness direction Z, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.

[0148] The electrode may include a negative current collector. The negative current collector has two surfaces opposite each other in its own thickness direction Z, and the negative active material is disposed on either or both of the two opposite surfaces of the negative current collector.

[0149] The positive electrode 223 and the negative electrode 224 are in a straight shape in the flat region 22A.

[0150] In some embodiments, referring to FIG5, the electrode assembly 22 has a wound structure, including a flat region 22A and two bent regions 22B, which are respectively connected to the two ends of the flat region 22A in the second direction Y. The positive electrode 223 and the negative electrode 224 are flat in the flat region 22A and bent in the bent regions 22B. The first direction X is perpendicular to the second direction Y. The first direction X may be parallel to the winding axis of the electrode assembly 22, and the second direction Y may be parallel to the length direction of the electrode assembly 22.

[0151] In some embodiments, referring to FIG6, the electrode assembly 22 is a stacked structure, and the positive electrode 223 and the negative electrode 224 are both flat and stacked along the first direction X.

[0152] In some embodiments, the two surfaces of the electrode assembly 22 disposed opposite to each other in the first direction X are the largest surfaces of the electrode assembly 22.

[0153] Understandably, the flat region 22A has a larger area, making it easier for lithium plating to occur, which in turn causes the electrode assembly 22 to expand along the first direction X and exert an expansion force on the first wall 211A.

[0154] In this embodiment, since the flat region 22A of the electrode assembly 22 is prone to expansion, and since the positive electrode 223 and the negative electrode 224 located in the flat region 22A are stacked along the first direction X, when the electrode assembly 22 expands due to long-term use, the expansion force exerted by the electrode assembly 22 on the first wall 211A in the first direction X is greater than the expansion force exerted by the electrode assembly 22 on the housing 211 in other directions. As a result, the risk of cracking at the connection between the first wall 211A and the end cap 212 is greater than the risk of cracking at the connection between other walls of the housing 211 and the end cap 212. By connecting the first buffer portion 2122 between the end cap body 2121 and the first wall 211A, the first buffer portion 2122 can deform first to buffer the expansion force of the electrode assembly 22, thereby reducing the risk of cracking at the first weld and improving the reliability of the battery cell 20.

[0155] According to some embodiments of this application, please refer to Figures 3 and 4, and also to Figures 5 and 6. The electrode assembly 22 includes a positive electrode 223 and a negative electrode 224. The negative electrode 224 includes a negative active material, which includes a silicon-based material.

[0156] The negative electrode 224 includes a negative electrode active material. For example, the negative electrode active material coated on the negative electrode 224 can be used to form a negative electrode active material layer, which can be disposed on at least one side of the surface of the negative electrode current collector. Exemplarily, negative electrode active material layers can be disposed on both sides of the negative electrode current collector perpendicular to its thickness direction.

[0157] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. Examples of metal foils include copper foil, copper alloy foil, aluminum foil, and aluminum alloy foil. The composite current collector may include a polymer substrate and a metal material layer formed on at least one surface of the polymer substrate. Examples of the metal material include one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Examples of the polymer substrate include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0158] Understandably, the negative electrode active material included in the negative electrode 224 can be flexibly configured according to actual applications. For example, the negative electrode active material may include a silicon-based material. When a silicon-based material is added to the negative electrode 224, the silicon-based material can accommodate more metal ions, effectively increasing the energy density of the battery cell 20. Additionally, it increases the deformation of the electrode assembly 22 within the battery cell 20 during use. Especially during the charging process of the battery cell 20, the embedding of metal ions into the silicon-based material of the negative electrode 224 causes the electrode assembly 22 to expand in volume, thereby increasing the pressure of the electrode assembly 22 on the casing 211 of the battery cell 20. Particularly in embodiments where the portion of the positive electrode 223 located in the flat region 22A and the portion of the negative electrode 224 located in the flat region 22A are stacked along the first direction X, the volume expansion of the electrode assembly 22 gradually accumulates along the first direction X, thereby increasing the pressure of the electrode assembly 22 on the first wall 211A of the casing 211, thus increasing the risk of cracking of the first weld.

[0159] In this embodiment, the silicon-based material on the negative electrode 224 can accommodate more metal ions, thereby effectively increasing the energy density of the battery cell 20. Furthermore, the presence of a silicon-based material in the negative electrode active material of the negative electrode 224 increases the deformation of the electrode assembly 22 within the battery cell 20 during use. Especially during charging, the embedding of metal ions into the silicon-based material of the negative electrode 224 causes the electrode assembly 22 to expand in volume, increasing the pressure exerted by the electrode assembly 22 on the first wall 211A. Therefore, by connecting the first buffer portion 2122 between the end cap body 2121 and the first wall 211A, when the first wall 211A is subjected to the expansion force of the electrode assembly 22, the first buffer portion 2122 can deform first, buffering the expansion force or external load of the electrode assembly 22, thereby reducing the risk of cracking at the first weld and improving the reliability of the battery cell 20.

[0160] According to some embodiments of this application, silicon-based materials include one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, silicon-containing alloys, or silicon-oxygen-carbon composites.

[0161] Understandably, the negative electrode active material can be flexibly configured according to the actual application. An exemplary negative electrode active material may include a silicon-based material, thereby increasing the energy density of the battery. For example, the silicon-based material may include at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, silicon-containing alloys, or silicon-oxygen-carbon composites.

[0162] In some embodiments, the silicon-based material may include silicon and one or more alkali metals and alkaline earth metals. For example, the alkali metal may include Li. As an example, the alkaline earth metal may include Mg. For example, the silicon-based material may be a silicon-based material pre-intercalated with alkali metals and / or alkaline earth metals, such as a silicon-based material pre-intercalated with Li and / or Mg.

[0163] In the embodiments of this application, the negative electrode active material may also include other materials. For example, the negative electrode active material may also include a negative electrode binder. For example, the negative electrode binder may include one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS), and the embodiments of this application are not limited thereto.

[0164] In some embodiments, the negative electrode active material may further include a negative electrode conductive agent. This application does not impose any particular limitation on the type of negative electrode conductive agent. As an example, the negative electrode conductive agent may include one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0165] In some embodiments, the negative electrode active material may also include other additives. As an example, other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, etc.

[0166] The negative electrode 224 does not exclude other additional functional layers besides the negative electrode active material layer. Exemplarily, in some embodiments, the negative electrode 224 may also include a conductive undercoating (e.g., composed of a conductive agent and an adhesive) sandwiched between the negative electrode current collector and the negative electrode active material layer and disposed on the surface of the negative electrode current collector; in some embodiments, the negative electrode may also include a protective layer covering the surface of the negative electrode active material layer.

[0167] In this embodiment, each material is easy to process and meets design requirements. Specifically, silicon-based materials are added to the negative electrode active material of the negative electrode sheet 224. Since silicon-based materials can accommodate more metal ions than other elements (for example, the capacity of silicon-based materials is about ten times that of graphite), the energy density of the battery cell 20 can be effectively improved. However, this also increases the deformation of the electrode assembly 22 within the battery cell 20 during use. Especially during the charging process of the battery cell 20, the embedding of metal ions into the silicon-based material of the negative electrode sheet 224 causes the electrode assembly 22 to expand in volume, thereby increasing the pressure of the electrode assembly 22 on the first wall 211A. Therefore, a first buffer portion 2122 is connected between the end cap body 2121 and the first wall 211A. When the first wall 211A is subjected to the expansion force of the electrode assembly 22, the first buffer portion 2122 can deform first to buffer the expansion force or external load of the electrode assembly 22, thereby reducing the risk of cracking at the first weld and improving the reliability of the battery cell 20.

[0168] According to some embodiments of this application, please refer to Figures 3 and 4, and also to Figures 5 and 6. The electrode assembly 22 includes a positive electrode 223 and a negative electrode 224. The positive electrode 223 includes a positive active material, which includes a nickel compound.

[0169] For example, the nickel-containing compound comprises layered lithium-containing transition metal oxides.

[0170] Understandably, if the positive electrode active material of the positive electrode 223 of the electrode assembly 22 includes a nickel-containing compound, and thermal runaway occurs in the battery cell 20, the internal temperature of the battery cell 20 will increase rapidly and a large amount of gas will be generated. This will increase the pressure inside the containment cavity, thereby increasing the internal pressure borne by the first wall 211A.

[0171] In this embodiment, when the positive electrode active material of the positive electrode 223 includes a nickel-containing compound, on the one hand, the energy density and cycle life of the battery cell 20 can be effectively increased; on the other hand, it will also increase the gas generated during the use of the battery cell 20, especially in the event of thermal runaway, the internal temperature of the battery cell 20 will increase rapidly and a large amount of gas will be generated, thereby increasing the internal pressure on the first wall 211A. Therefore, the first buffer part 2122 is connected between the end cap body 2121 and the first wall 211A. When the first wall 211A is subjected to the expansion force of the electrode assembly 22, the first buffer part 2122 can deform first to buffer the expansion force or external load of the electrode assembly 22, thereby reducing the risk of cracking at the first weld and improving the reliability of the battery cell 20.

[0172] According to some embodiments of this application, please refer to Figure 7, and also to Figures 8-10. Figure 7 is a partial enlarged view of point A in Figure 4, and Figures 8-10 are cross-sectional views of three other first buffer portions 2122 provided in some embodiments of this application. The end cap body 2121 is a flat plate structure, and the first buffer portion 2122 is a bent structure.

[0173] The end cap body 2121 has a flat plate structure, which facilitates drilling and other machining of the end cap body 2121, so as to install structural components of the battery cell 20 such as electrode terminals 23 and explosion-proof valves on the end cap body 2121.

[0174] The first buffer portion 2122 being a bent structure means that the first buffer portion 2122 can be bent, recessed, or protruding. For example, referring to Figures 7 and 8, the bent structure can be a protrusion on one or the other side of the end cap 212 along its thickness direction Z. There can be one or more protrusions, and the orientation of the multiple protrusions can be the same or different.

[0175] In some embodiments, referring to FIG7, the first buffer portion 2122 is bent to form a plurality of protrusions. The protrusions protrude from the side of the end cap 212 facing the electrode assembly 22. The battery cell 20 can abut against other structural members in the battery device 100 in the thickness direction Z of the end cap 212, thereby reducing the volume of the battery device 100 occupied by the battery cell 20 in the thickness direction Z of the end cap 212, so that more battery cells 20 can be accommodated in the battery device 100, and increasing the energy density of the battery device 100.

[0176] In some embodiments, referring to FIG8, the first buffer portion 2122 is bent to form a plurality of protrusions, the protrusions protruding from the side of the end cap 212 away from the electrode assembly 22, so that the deformation of the first buffer portion 2122 can be completed on the side of the end cap 212 away from the electrode assembly 22, thereby reducing the risk of lithium plating and increased expansion caused by the first buffer portion 2122 squeezing the electrode assembly 22 during the deformation process.

[0177] In some embodiments, referring to Figures 7 and 8, the first buffer portion 2122 may be in the form of multiple continuous arcs to reduce stress concentration at the bend.

[0178] In some embodiments, referring to Figures 9 and 10, the first buffer portion 2122 may be in the form of multiple continuous straight bending segments to facilitate the processing of the first buffer portion 2122 by the processing device.

[0179] In this embodiment, the first buffer portion 2122 is a bent structure, such that the dimension of the first buffer portion 2122 in its bending direction is greater than its dimension in the first direction X. Therefore, when the first wall 211A is subjected to the expansion force of the electrode assembly 22 or external load, the first buffer portion 2122 can be stretched and bent to allow the first buffer portion 2122 to be relatively displaced in the first direction X at the end connected to the end cap body 2121 and the end connected to the first wall 211A, so as to buffer the expansion force of the electrode assembly 22 or external load, thereby reducing the risk of cracking at the first weld and improving the reliability of the battery cell 20.

[0180] According to some embodiments of this application, please refer to FIG11, which is a schematic diagram of the structure of a battery cell 20 provided in some embodiments of this application. The first buffer portion 2122 extends along the second direction Y, and the thickness direction Z of the end cap 212 is perpendicular to the first direction X and the second direction Y.

[0181] In some embodiments, the housing 211 has a third wall 211C and a fourth wall 211D disposed opposite each other in the second direction Y, and a first buffer portion 2122 extends from the third wall 211C to the fourth wall 211D.

[0182] In some embodiments, the housing 211 has a third wall 211C and a fourth wall 211D disposed opposite each other in the second direction Y, and a first buffer portion 2122 has a gap between one end in the second direction Y and the third wall 211C, and a gap between the other end of the first buffer portion 2122 in the second direction Y and the fourth wall 211D.

[0183] In this embodiment, the first buffer portion 2122 extends along the second direction Y, thereby increasing the area of ​​the first buffer portion 2122 while keeping its size in the first direction X. As a result, when the electrode assembly 22 expands, the first buffer portion 2122 can generate greater deformation, which is beneficial to improving the buffering effect of the first buffer portion 2122 on the expansion force of the electrode assembly 22. This further reduces the magnitude of the force borne at the connection between the first wall 211A and the first buffer portion 2122, thereby reducing the risk of cracking at the first weld and improving the reliability of the battery cell 20.

[0184] According to some embodiments of this application, please refer to Figures 12 and 13. Figure 12 is a schematic diagram of the structure of the first buffer portion 2122 after bending according to some embodiments of this application; Figure 13 is a schematic diagram of the structure of the first buffer portion 2122 before bending according to some embodiments of this application. The dimension of the first buffer portion 2122 in the first direction X is H1, and the length of the first buffer portion 2122 along its bending direction is H2, satisfying that 1.05≤H2 / H1≤5.

[0185] The dimension of the first buffer portion 2122 in the first direction X is the length of the first buffer portion 2122 after being bent and shaped, from the end furthest from the first wall 211A in the first direction X to the end closest to the first wall 211A.

[0186] The length of the first buffer portion 2122 along its bending direction is the length from the end furthest from the end cap body 2121 in the first direction X to the end closest to the end cap body 2121 before the first buffer portion 2122 is bent into shape.

[0187] H2 / H1 can take any point value from 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.5, 3, 3.5, 4, 4.55, etc., or a range between any two.

[0188] In this embodiment, when H2 / H1≥1.05, the dimension of the first buffer portion 2122 in its bending direction is larger than its dimension in the first direction X. This allows the relative displacement of the two ends of the first buffer portion 2122 in the first direction X to have a larger range when the first wall 211A is subjected to the expansion force of the electrode assembly 22 or external load, thereby reducing the risk of cracking at the first weld and improving the reliability of the battery cell 20. When H2 / H1≤5, the dimension of the first buffer portion 2122 in its bending direction can be reduced, thereby reducing the risk of cracking at the first weld. The buffer portion 2122 has a dimension in the thickness direction Z of the end cap 212, thereby reducing the space occupied by the end cap 212 in the thickness direction Z, thus reducing the space occupied by the battery cell 20 in the thickness direction Z, and thus increasing the energy density of the battery cell 20 without changing the volume of the electrode assembly 22. Therefore, when 1.05≤H2 / H1≤5, the battery cell 20 with the first buffer portion 2122 can reduce the risk of cracking at the first weld, thereby improving the reliability of the battery cell 20 and increasing the energy density of the battery cell 20.

[0189] According to some embodiments of this application, please refer to Figures 12 and 13, 1.1≤H2 / H1≤2.

[0190] H2 / H1 can take any point value from 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.6, 1.7, 1.8, 1.9, 2, etc., or any range value between the two.

[0191] In this embodiment, when H2 / H1≥1.1, the dimension of the first buffer portion 2122 in its bending direction can be further increased to be larger than its dimension in the first direction X. This allows the relative displacement of the two ends of the first buffer portion 2122 in the first direction X to have a larger range when the first wall 211A is subjected to the expansion force of the electrode assembly 22 or external load, thereby further reducing the risk of cracking at the first weld and further improving the reliability of the battery cell 20. When H2 / H1≤2, the dimension of the first buffer portion 2122 in its bending direction can be further reduced, thereby further improving the reliability of the battery cell 20. By gradually reducing the size of the first buffer portion 2122 in the thickness direction Z of the end cap 212, the space occupied by the end cap 212 in the thickness direction Z is reduced, thereby further reducing the space occupied by the battery cell 20 in the thickness direction Z, and thus increasing the energy density of the battery cell 20 without changing the volume of the electrode assembly 22. Therefore, when 1.1≤H2 / H1≤2, the battery cell 20 with the first buffer portion 2122 can further reduce the risk of cracking at the first weld, thereby improving the reliability of the battery cell 20, and at the same time, can further increase the energy density of the battery cell 20.

[0192] According to some embodiments of this application, please refer to Figures 12 and 13, 0.5mm≤H1≤40mm.

[0193] H1 can be any point value or a range between any two of the following: 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm.

[0194] In this embodiment, when H1 ≥ 0.5 mm, the first buffer portion 2122 can have a certain size in the first direction X, which facilitates the machining of the first buffer portion 2122 by external processing tools such as stamping devices. When H1 ≤ 40 mm, with the end cap 212 having a fixed size in the first direction X, H1 ≤ 40 mm can ensure that the end cap body 2121 has a sufficient size in the first direction X, thereby improving the strength of the end cap body 2121 and providing a more stable working environment for other structural components of the battery cell 20 installed on the end cap body 2121, thereby improving the reliability of the battery cell 20. Therefore, when 0.5 mm ≤ H1 ≤ 40 mm, the battery cell 20 with the first buffer portion 2122 can facilitate the machining of the first buffer portion 2122 by external processing tools, and at the same time can provide a more stable working environment for other structural components of the battery cell 20 installed on the end cap body 2121, thereby improving the reliability of the battery cell 20.

[0195] According to some embodiments of this application, please refer to Figures 12 and 13, 1mm ≤ H2 ≤ 40mm.

[0196] H2 can be any point value or a range of any two of the following: 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, 25mm, 30mm, 35mm, 40mm.

[0197] In this embodiment, when H2 ≥ 1 mm, the first buffer portion 2122 has a certain size in its bending direction, so that when the first wall 211A is subjected to the expansion force of the electrode assembly 22 or external load, the two ends of the first buffer portion 2122 can be relatively displaced in the first direction X, thereby reducing the risk of cracking at the first weld and improving the reliability of the battery cell 20. When H2 ≤ 40 mm, the size of the first buffer portion 2122 in its bending direction can be reduced, and the size of the first buffer portion 2122 in the thickness direction Z of the end cover 212 can be further reduced, thereby reducing the space occupied by the end cover 212 in the thickness direction Z, and further reducing the space occupied by the battery cell 20 in the thickness direction Z, thereby increasing the energy density of the battery cell 20 without changing the volume of the electrode assembly 22. Therefore, when 1 mm ≤ H2 ≤ 40 mm, the risk of cracking at the first weld can be reduced, thereby improving the reliability of the battery cell 20 and increasing the energy density of the battery cell 20.

[0198] According to some embodiments of this application, referring to Figures 12 and 13, the maximum thickness of the end cap body 2121 is T1, and the thickness of the first buffer portion 2122 is T2, satisfying 0.1≤T2 / T1≤0.9.

[0199] The maximum thickness of the end cap body 2121 is the thickness of the end cap body 2121 from the side furthest from the electrode assembly 22 to the side closest to the electrode assembly 22 in the thickness direction Z of the end cap 212.

[0200] The thickness of the first buffer portion 2122 is the thickness of the first buffer portion 2122 before bending, from the side away from the electrode assembly 22 in the thickness direction Z of the end cap 212 to the side close to the electrode assembly 22.

[0201] T2 / T1 can take any point value from 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or any range between the two.

[0202] In this embodiment, when T2 / T1≥0.1, the first buffer portion 2122 can have a certain thickness relative to the first wall 211A, thereby reducing the thickness difference between the end cap body 2121 and the first buffer portion 2122, and thus reducing the stress concentration at the transition between the end cap body 2121 and the first buffer portion 2122, thereby reducing the risk of cracking of the cap body and the first buffer portion 2122; when T2 / T1≤0.9, the thickness of the first buffer portion 2122 can be less than the thickness of the end cap body 2121, thereby making the first buffer portion 2122 relatively... The end cap body 2121 is more prone to deformation, and thus, compared with the battery cell 20 without the first buffer part 2122, the battery cell 20 can reduce the risk of cracking at the first weld, thereby improving the reliability of the battery cell 20. Therefore, when 0.1≤T2 / T1≤0.9, the battery cell 20 with the first buffer part 2122 can reduce the stress concentration at the transition between the end cap body 2121 and the first buffer part 2122, thereby reducing the risk of cracking of the end cap body and the first buffer part 2122, and also reducing the risk of cracking at the first weld.

[0203] According to some embodiments of this application, please refer to Figures 12 and 13, 0.1mm≤T2≤2.5mm.

[0204] T2 can be any point value or a range between any two of the following: 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.5mm, 2mm, 2.5mm.

[0205] In this embodiment, when T2 ≥ 0.1 mm, the first buffer portion 2122 can have a certain thickness, which facilitates the processing of the first buffer portion 2122, reduces the processing difficulty of the first buffer portion 2122, and thus improves the yield of the battery cell 20 with the first buffer portion 2122. When T2 ≤ 2.5 mm, the structural strength of the first buffer portion 2122 is lower. When the first wall 211A bears the expansion force of the electrode assembly 22, the first buffer portion 2122 can deform more easily, thereby reducing the magnitude of the force borne by the first weld and thus reducing the risk of cracking at the first weld. Therefore, when 0.1 mm ≤ T2 ≤ 2.5 mm, the yield of the battery cell 20 with the first buffer portion 2122 can be improved, while further reducing the risk of cracking at the first weld.

[0206] According to some embodiments of this application, please refer to Figures 12 and 13, 0.3mm≤T1≤5mm.

[0207] T1 can be any point value or a range between any two of the following: 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm.

[0208] In this embodiment, when T1 ≥ 0.3 mm, the end cap body 2121 can have a certain structural strength, thereby providing a more stable working environment for other structural components of the battery cell 20 set on the end cap body 2121, thus improving the reliability of the battery cell 20. When T1 ≤ 5 mm, the size of the end cap body 2121 in its thickness direction Z can be reduced, thereby increasing the volume of the internal space of the outer shell 21 while keeping the volume of the outer shell 21 constant. This allows the internal space to accommodate a larger electrode assembly 22, increasing the energy density of the battery cell 20. Therefore, when 0.3 mm ≤ T1 ≤ 5 mm, the reliability of the battery cell 20 with the end cap body 2121 can be improved, and the energy density of the battery cell 20 can be increased at the same time.

[0209] According to some embodiments of this application, please refer to FIG14, which is a cross-sectional view of another housing 21 provided in some embodiments of this application. The end cap 212 is welded to the first wall 211A to form a first weld portion 2126.

[0210] The first welding part 2126 is the weld mark after the end cover 212 and the first wall 211A are welded together, that is, the part that connects the end cover 212 and the first wall 211A after welding.

[0211] "The end cap 212 is welded to the first wall 211A to form the first welded part 2126" can also be understood as the end cap 212 and the first wall 211A being connected through the first welded part 2126.

[0212] In some embodiments, the first weld portion 2126 is located inside the housing 21. In some embodiments, the first weld portion 2126 is located outside the housing 21.

[0213] In this embodiment, the end cap 212 and the first wall 211A are connected by welding to form a first welded part 2126, which can effectively improve the connection strength and reliability between the end cap 212 and the first wall 211A, and help reduce the risk of the end cap 212 and the first wall 211A falling off each other during use, so as to improve the reliability of the battery cell 20.

[0214] According to some embodiments of this application, referring to FIG14, the distance between the first buffer portion 2122 and the first welding portion 2126 in the first direction X is H3, which satisfies 0.5mm≤H3≤6mm.

[0215] The distance between the first buffer portion 2122 and the first weld portion 2126 in the first direction X is the distance between the end of the first buffer portion 2122 closest to the first wall 211A in the first direction X and the end of the first weld portion 2126 closest to the first buffer portion 2122 in the first direction X.

[0216] H3 can be any point value or a range between any two of the following: 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm.

[0217] In this embodiment, when H3 ≥ 0.5 mm, the first buffer portion 2122 is at a certain distance from the first welding portion 2126 in the first direction X, thereby reducing the risk of welding material flowing into the first buffer portion 2122 and causing the buffering capacity of the first buffer portion 2122 to fail when welding the end cap 212 and the first wall 211A; when H3 ≤ 6 mm, the distance between the first buffer portion 2122 and the first wall 211A is small, and when the first wall 211A is subjected to the expansion force of the electrode assembly 22, it can be better transmitted to the first buffer portion 2122. This causes the first buffer portion 2122 to deform, thereby reducing the force borne by the first weld portion 2126 and lowering the risk of cracking of the first weld portion 2126. Therefore, when 0.5mm≤H3≤6mm, the risk of the first buffer portion 2122 failing due to the inflow of welding material into it can be reduced, while the force can be better transferred to the first buffer portion 2122, causing it to deform and thus reducing the force borne by the first weld portion 2126 and lowering the risk of cracking of the first weld portion 2126.

[0218] According to some embodiments of this application, please refer to Figure 14, 1mm≤H3≤4mm.

[0219] H3 can be any point value or a range between any two of the following: 1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm.

[0220] In this embodiment, when H3 ≥ 1 mm, the first buffer portion 2122 is positioned at a certain distance from the first welding portion 2126 in the first direction X. This further reduces the risk of welding material flowing into the first buffer portion 2122 and causing it to fail in its buffering capacity when welding the end cap 212 and the first wall 211A. When H3 ≤ 4 mm, the distance between the first buffer portion 2122 and the first wall 211A is smaller. When the first wall 211A is subjected to the expansion force of the electrode assembly 22, the force can be better transmitted to the first buffer portion 2122, thus improving the buffering capacity of the first buffer portion 2122. 2. Deformation further reduces the force borne by the first weld 2126, thereby further reducing the risk of cracking of the first weld 2126; therefore, when 1mm≤H3≤4mm, the risk of the first buffer 2122 failing due to the inflow of welding material into the first buffer 2122 can be further reduced, and the material can be better transferred to the first buffer 2122 so that the first buffer 2122 deforms, thereby further reducing the force borne by the first weld 2126, thereby further reducing the risk of cracking of the first weld 2126.

[0221] According to some embodiments of this application, the end cap body 2121 and the first buffer portion 2122 are integrally formed.

[0222] The end cap body 2121 and the first buffer part 2122 are integrally formed, and the first buffer part 2122 can be formed by processes such as stamping. This is beneficial to improving the connection strength between the end cap body 2121 and the first buffer part 2122, and also helps to simplify the manufacturing process of the shell end cap 212.

[0223] In this embodiment, the end cap body 2121 and the first buffer portion 2122 are integrally formed, which is beneficial to improving the connection strength between the end cap body 2121 and the first buffer portion 2122, and also helps to simplify the manufacturing process of the end cap 212.

[0224] According to some embodiments of this application, referring to FIG15, FIG15 is a schematic structural diagram of another battery cell 20 provided in some embodiments of this application. The housing 211 has a second wall 211B in the first direction X, the second wall 211B is disposed opposite to the first wall 211A, and the second wall 211B is connected to the end cap 212 through a second weld; the end cap 212 also includes a second buffer portion 2123, the second buffer portion 2123 is connected between the end cap body 2121 and the second wall 211B.

[0225] The second wall 211B is another wall portion of the housing 211 in the first direction X, and the second wall 211B is adjacent to the end cap 212 and opposite to the first wall 211A. For example, the first wall 211A, the second wall 211B and other walls of the housing 211 surround the edge of the end cap 212.

[0226] Optionally, the end cap body 2121 and the second buffer portion 2123 can be integrally formed, except that the corresponding structure and shape are processed at the corresponding position of the second buffer portion 2123. Of course, the end cap body 2121 and the second buffer portion 2123 can also be formed separately and then connected together.

[0227] Understandably, when the second wall 211B is subjected to the expansion force of the electrode assembly 22 or external load, the second buffer portion 2123 is more likely to deform than the end cap body 2121. The second buffer portion 2123 can deform first to buffer the expansion force of the electrode assembly 22 or external load, thereby reducing the risk of cracking at the second weld and improving the reliability of the battery cell 20.

[0228] The second buffer section 2123 is the part of the end cap 212 that deforms when the load is transmitted from the second wall 211B to the connection of the end cap 212. For example, the deformation can be elastic deformation or plastic deformation. The deformation generated by the second buffer section 2123 can be bending deformation or tensile deformation, etc.

[0229] The second buffer portion 2123 may be curved, recessed, or protruding, so that the second buffer portion 2123 can deform under the action of external force; or, the second buffer portion 2123 may be made of a flexible material such as a metal material or a non-metal material that is easy to stretch, so that it can deform under the action of external force.

[0230] In this embodiment, the end cap 212 further includes a second buffer portion 2123, which is connected between the end cap body 2121 and the second wall 211B. When the second wall 211B is subjected to the expansion force of the electrode assembly 22 or an external load, the second buffer portion 2123 can deform first to buffer the expansion force of the electrode assembly 22 or the external load, thereby reducing the risk of cracking at the connection between the end cap 212 and the second wall 211B, and thus improving the reliability of the battery cell 20.

[0231] According to some embodiments of this application, referring to FIG15, the housing 211 has a third wall 211C and a fourth wall 211D disposed opposite to each other in the second direction Y. The end cap 212 of the third wall 211C is connected by a third weld, and the end cap 212 of the fourth wall 211D is connected by a fourth weld. The thickness direction Z, the first direction X, and the second direction Y of the end cap 212 are perpendicular to each other. The end cap 212 also includes a third buffer portion 2124 and a fourth buffer portion 2125. The third buffer portion 2124 is connected between the end cap body 2121 and the third wall 211C, and the fourth buffer portion 2125 is connected between the end cap body 2121 and the fourth wall 211D.

[0232] The third wall 211C is a wall portion of the housing 211 in the first direction X, and the fourth wall 211D is another wall portion of the housing 211 in the first direction X. Both the third wall 211C and the fourth wall 211D are adjacent to the end cap 212. The third wall 211C and the fourth wall 211D are opposite each other in the second direction Y. For example, the first wall 211A, the second wall 211B, the third wall 211C and the fourth wall 211D surround the edge of the end cap 212.

[0233] Optionally, the end cap body 2121 and the third buffer portion 2124 can be integrally formed, with the corresponding structure and shape processed at the corresponding position of the third buffer portion 2124. Alternatively, the end cap body 2121 and the third buffer portion 2124 can be formed separately and then connected together; and / or, the end cap body 2121 and the fourth buffer portion 2125 can be integrally formed, with the corresponding structure and shape processed at the corresponding position of the fourth buffer portion 2125. Alternatively, the end cap body 2121 and the fourth buffer portion 2125 can be formed separately and then connected together.

[0234] Understandably, when the third wall 211C is subjected to the expansion force of the electrode assembly 22 or external load, the third buffer part 2124 is more likely to deform than the end cap body 2121. The third buffer part 2124 can deform first to buffer the expansion force of the electrode assembly 22 or external load, thereby reducing the risk of cracking at the third weld and improving the reliability of the battery cell 20.

[0235] Understandably, when the fourth wall 211D is subjected to the expansion force of the electrode assembly 22 or external load, the fourth buffer part 2125 is more likely to deform than the end cap body 2121. The fourth buffer part 2125 can deform first to buffer the expansion force of the electrode assembly 22 or external load, thereby reducing the risk of cracking at the fourth weld and improving the reliability of the battery cell 20.

[0236] The third buffer section 2124 is the part of the end cap 212 that deforms when the load is transmitted from the third wall 211C to the connection of the end cap 212. For example, the deformation can be elastic or plastic. The deformation generated by the third buffer section 2124 can be bending or tensile. The fourth buffer section 2125 is the part of the end cap 212 that deforms when the load is transmitted from the fourth wall 211D to the connection of the end cap 212. For example, the deformation can be elastic or plastic. The deformation generated by the fourth buffer section 2125 can be bending or tensile.

[0237] The third buffer portion 2124 may be curved, recessed, or protruding, so that it can deform under the action of external force; or, the third buffer portion 2124 may be made of a flexible material such as a stretchable metal or non-metal material, so that it can deform under the action of external force; the fourth buffer portion 2125 may be curved, recessed, or protruding, so that it can deform under the action of external force; or, the fourth buffer portion 2125 may be made of a flexible material such as a stretchable metal or non-metal material, so that it can deform under the action of external force.

[0238] In this embodiment, the end cap 212 further includes a third buffer portion 2124 and a fourth buffer portion 2125. The third buffer portion 2124 is connected between the end cap body 2121 and the third wall 211C, and the fourth buffer portion 2125 is connected between the end cap body 2121 and the fourth wall 211D. When the third wall 211C is subjected to the expansion force of the electrode assembly 22 or an external load, the third buffer portion 2124 can deform first to buffer the expansion force of the electrode assembly 22 or the external load, thereby reducing the risk of cracking at the connection between the end cap 212 and the third wall 211C. When the fourth wall 211D is subjected to the expansion force of the electrode assembly 22 or an external load, the fourth buffer portion 2125 can deform first to buffer the expansion force of the electrode assembly 22 or the external load, thereby reducing the risk of cracking at the connection between the end cap 212 and the fourth wall 211D, thereby improving the reliability of the battery cell 20.

[0239] According to some embodiments of this application, referring to FIG15, the first buffer portion 2122, the third buffer portion 2124, the second buffer portion 2123 and the fourth buffer portion 2125 are connected end to end in sequence.

[0240] In this embodiment, the first buffer portion 2122, the third buffer portion 2124, the second buffer portion 2123, and the fourth buffer portion 2125 are connected end to end in sequence. So when the junction of the first wall 211A, the third wall 211C, the second wall 211B, and the fourth wall 211D is subjected to the expansion force of the electrode assembly 22, the junction of the first buffer portion 2122, the third buffer portion 2124, the second buffer portion 2123, and the fourth buffer portion 2125 can deform first to buffer the expansion force or external load of the electrode assembly 22. This reduces the risk of the connection between the end cap 212 and the fourth wall 211D cracking at the junction of the first buffer portion 2122, the third buffer portion 2124, the second buffer portion 2123, and the fourth buffer portion 2125, thereby improving the reliability of the battery cell 20.

[0241] According to some embodiments of this application, the outer casing 21 is made of aluminum or an aluminum alloy.

[0242] Aluminum and aluminum alloys are existing materials. Aluminum can be a metallic material made from elemental aluminum, while aluminum alloys can be alloy materials composed primarily of aluminum.

[0243] In this embodiment, the materials are easy to process and meet design requirements. Specifically, aluminum and aluminum alloys have good corrosion resistance and make the outer shell easily deformable. On the one hand, this provides an expandable space for the electrode assembly to accommodate its expansion, which helps to improve the service life of the battery cell. On the other hand, in this case, the first buffer part is connected between the end cap body and the first wall. When the first wall is subjected to the expansion force of the electrode assembly, the first buffer part can deform first to buffer the expansion force or external load of the electrode assembly, thereby reducing the risk of cracking at the first weld and improving the reliability of the battery cell.

[0244] According to some embodiments of this application, a battery device 100 is also provided, which includes the battery cell 20 provided above.

[0245] Referring to FIG2, the battery device 100 may further include a housing 10, in which the battery cells 20 are housed.

[0246] In some embodiments, the housing 10 may include a first housing body 11 and a second housing body 12, the first housing body 11 and the second housing body 12 covering each other, the first housing body 11 and the second housing body 12 together defining an assembly space for accommodating the battery cell 20.

[0247] Optionally, the second box body 12 can be a hollow structure with one end open, and the first box body 11 can be a plate-like structure. The first box body 11 covers the open side of the second box body 12 so that the first box body 11 and the second box body 12 together define the assembly space; the first box body 11 and the second box body 12 can also be hollow structures with one side open, and the open side of the first box body 11 covers the open side of the second box body 12.

[0248] Of course, the box 10 formed by the first box body 11 and the second box body 12 can be of various shapes, such as a cylinder or a cuboid. For example, referring to FIG2, the box 10 is a cuboid structure.

[0249] Optionally, the battery cell 20 disposed within the housing 10 can be one or more. For example, referring to Figure 2, the housing 10 of the battery device 100 contains multiple battery cells 20. These multiple battery cells 20 can be connected in series, parallel, or a combination thereof. A combination thereof means that some of the multiple battery cells 20 are connected in series and others in parallel. The multiple battery cells 20 can be directly connected in series, parallel, or a combination thereof, and then the entire assembly of the multiple battery cells 20 is housed within the housing 10.

[0250] The battery device 100 may also include other structures. For example, the battery device 100 may also include a busbar component that connects multiple battery cells 20 to achieve electrical connection between the multiple battery cells 20.

[0251] It should be noted that in some embodiments, the battery device 100 may not have a housing 10. The battery device 100 includes multiple battery cells 20, and the battery device 100 composed of multiple battery cells 20 can be directly mounted onto the electrical device to provide power to the electrical device through the multiple battery cells 20. That is, the housing 10 can be part of the electrical device. Taking a vehicle 1000 as an example, the housing 10 can be part of the chassis structure of the vehicle 1000. For example, a portion of the housing 10 can be at least a part of the floor of the vehicle 1000, or a portion of the housing 10 can be at least a part of the crossbeams and longitudinal beams of the vehicle 1000.

[0252] According to some embodiments of this application, some embodiments of this application also provide an electrical device, which includes a battery cell 20 as described above, the battery cell 20 being used to provide electrical energy.

[0253] According to some embodiments of this application, please refer to Figures 3-15. A battery cell 20 is provided, including a housing 21 and an electrode assembly 22. The housing 21 includes a shell 211 and an end cap 212. The shell 211 has an opening, and the end cap 212 closes the opening and is connected to the shell 211. The shell 211 and the end cap 212 enclose a receiving cavity. The electrode assembly 22 is received in the receiving cavity. The shell 211 has a first wall 211A in a first direction X. The first wall 211A is connected to the end cap 212. The end cap 212 includes an end cap body 2121 and a first buffer portion 2122. The first buffer portion 2122 is connected between the end cap body 2121 and the first wall 211A.

[0254] Electrode assembly 22 includes a positive electrode 223 and a negative electrode 224. Electrode assembly 22 has a flat region 22A. The portions of the positive electrode 223 and the negative electrode 224 located in the flat region 22A are stacked along a first direction X. The negative electrode 224 includes a negative electrode active material, which may be a silicon-based material. The silicon-based material may be one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, silicon-containing alloys, or silicon-oxygen-carbon composites. The positive electrode 223 includes a positive electrode active material, which may be a nickel compound.

[0255] The end cap body 2121 is a flat plate structure, and the first buffer part 2122 is a bent structure.

[0256] The first buffer portion 2122 extends along the second direction Y, and the thickness direction Z of the end cap 212, the first direction X, and the second direction Y are perpendicular to each other.

[0257] The first buffer section 2122 has a dimension of H1 in the first direction X, and a length of H2 along its bending direction, satisfying that 1.1≤H2 / H1≤2, 0.5mm≤H1≤40mm, and 1mm≤H2≤40mm.

[0258] The maximum thickness of the end cap body 2121 is T1, and the thickness of the first buffer part 2122 is T2, satisfying the following conditions: 0.1≤T2 / T1≤0.9, 0.1mm≤T2≤2.5mm, and 0.3mm≤T1≤5mm.

[0259] The end cap 212 is welded to the first wall 211A to form a first welded part 2126. The distance between the first buffer part 2122 and the first welded part 2126 in the first direction X is H3, which satisfies that 1mm≤H3≤4mm.

[0260] The end cap body 2121 and the first buffer part 2122 are integrally formed.

[0261] The housing 211 has a second wall 211B in the first direction X, which is opposite to the first wall 211A. The second wall 211B is connected to the end cap 212 by a second weld. The end cap 212 also includes a second buffer portion 2123, which is connected between the end cap body 2121 and the second wall 211B. The housing 211 has a third wall 211C and a fourth wall 211D opposite to each other in the second direction Y. The third wall 211C is connected to the end cap 212 by a third weld, and the fourth wall 211D is connected to the end cap 212 by a fourth weld. The thickness direction Z of the end cap 212 is perpendicular to both the first direction X and the second direction Y. The end cap 212 also includes a third buffer portion 2124 and a fourth buffer portion 2125. The third buffer portion 2124 is connected between the end cap body 2121 and the third wall 211C, and the fourth buffer portion 2125 is connected between the end cap body 2121 and the fourth wall 211D. The first buffer section 2122, the third buffer section 2124, the second buffer section 2123, and the fourth buffer section 2125 are connected end to end in sequence. The outer shell 21 is made of aluminum or aluminum alloy.

[0262] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A single battery cell, comprising: The housing includes a shell and an end cap, the shell having an opening, the end cap closing onto the opening and being connected to the shell, the shell and the end cap forming a receiving cavity; The electrode assembly is housed within the receiving cavity; The housing has a first wall in a first direction, and the first wall is connected to the end cap by a first weld. The end cap includes an end cap body and a first buffer portion, and the first buffer portion is connected between the end cap body and the first wall.

2. The battery cell as described in claim 1, wherein, The electrode assembly includes a positive electrode and a negative electrode. The electrode assembly has a flat region, and the portion of the positive electrode located in the flat region and the portion of the negative electrode located in the flat region are stacked along the first direction.

3. The battery cell as described in claim 1 or 2, wherein, The electrode assembly includes a positive electrode and a negative electrode, the negative electrode includes a negative electrode active material, and the negative electrode active material includes a silicon-based material.

4. The battery cell as described in claim 3, wherein, The silicon-based material includes one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, silicon-containing alloy, or silicon-oxygen-carbon composite material.

5. The battery cell according to any one of claims 1-4, wherein, The electrode assembly includes a positive electrode and a negative electrode, the positive electrode includes a positive active material, and the positive active material includes a nickel compound.

6. The battery cell according to any one of claims 1-5, wherein, The end cap body is a flat plate structure, and the first buffer part is a bent structure.

7. The battery cell according to any one of claims 1-6, wherein, The first buffer portion extends along the second direction, and the thickness direction of the end cap, the first direction, and the second direction are perpendicular to each other.

8. The battery cell according to any one of claims 1-7, wherein, The first buffer portion has a dimension of H1 in the first direction and a length of H2 along its bending direction, satisfying 1.05≤H2 / H1≤5.

9. The battery cell as described in claim 8, wherein, 1.1≤H2 / H1≤2.

10. The battery cell as described in claim 8 or 9, wherein, 0.5mm≤H1≤40mm.

11. The battery cell according to any one of claims 8-10, wherein, 1mm≤H2≤40mm.

12. The battery cell according to any one of claims 1-11, wherein, The maximum thickness of the end cap body is T1, and the thickness of the first buffer part is T2, satisfying 0.1≤T2 / T1≤0.

9.

13. The battery cell as described in claim 12, wherein, 0.1mm≤T2≤2.5mm.

14. The battery cell as described in claim 12 or 13, wherein, 0.3mm≤T1≤5mm.

15. The battery cell according to any one of claims 1-14, wherein, The end cap is welded to the first wall to form a first welded portion.

16. The battery cell as described in claim 15, wherein, The distance between the first buffer part and the first welding part in the first direction is H3, which satisfies 0.5mm≤H3≤6mm.

17. The battery cell as claimed in claim 16, wherein, 1mm≤H3≤4mm.

18. The battery cell according to any one of claims 1-17, wherein, The end cap body and the first buffer part are integrally formed.

19. The battery cell according to any one of claims 1-18, wherein, The housing has a second wall in a first direction, the second wall being disposed opposite to the first wall, and the second wall being connected to the end cap by a second weld. The end cap further includes a second buffer portion, which is connected between the end cap body and the second wall.

20. The battery cell as claimed in claim 19, wherein, The housing has a third wall and a fourth wall that are arranged opposite to each other in the second direction. The third wall is connected to the end cap by a third weld, and the fourth wall is connected to the end cap by a fourth weld. The thickness direction of the end cap, the first direction, and the second direction are perpendicular to each other. The end cap further includes a third buffer portion and a fourth buffer portion. The third buffer portion is connected between the end cap body and the third wall, and the fourth buffer portion is connected between the end cap body and the fourth wall.

21. The battery cell as described in claim 20, wherein, The first buffer section, the third buffer section, the second buffer section, and the fourth buffer section are connected end to end in sequence.

22. The battery cell according to any one of claims 1-21, wherein, The outer shell is made of aluminum or aluminum alloy.

23. A battery device comprising a plurality of battery cells according to any one of claims 1-22.

24. An electrical device comprising a battery cell according to any one of claims 1-22, said battery cell being used to provide electrical energy.

Images