Battery cells, battery devices and power-consuming devices

Abstract

This application provides a battery cell, a battery device, and an electrical device. The battery cell includes an electrode assembly and a housing. The electrode assembly is housed within the housing. The housing includes a wall portion, which includes a wall body and a first protective layer. The first protective layer is disposed on the outer side of the wall body and covers at least a portion of the outer surface of the wall body. The wall body is made of carbon steel, and the first protective layer is made of stainless steel. The wall body of the housing is made of carbon steel, giving the housing advantages such as high strength, low manufacturing cost, and good machinability. The first protective layer, made of stainless steel, on the outer side of the wall body reduces the risk of rust, extends the service life of the housing, and improves the reliability of the housing, thereby improving the reliability and extending the lifespan of the battery cell. Furthermore, the stainless steel material of the first protective layer results in lower cost.

Description

Technical Field

[0001] 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

[0002] Batteries are widely used in new energy vehicles, electronic devices, and other fields. As the demand for batteries increases, higher requirements are being placed on their reliability. Summary of the Invention

[0003] This application provides a battery cell, a battery device, and an electrical device, which can improve the reliability of the battery cell.

[0004] In a first aspect, embodiments of this application provide a battery cell, the battery cell including an electrode assembly and a housing; the electrode assembly is housed within the housing, the housing including a wall portion, the wall portion including a wall body and a first protective layer, the first protective layer being disposed on the outside of the wall body and covering at least a portion of the outer surface of the wall body, the wall body being made of carbon steel, the first protective layer being made of stainless steel, the stainless steel including nickel and chromium, the nickel accounting for 2% to 20% by weight, and the chromium accounting for 10% to 26% by weight.

[0005] In the above technical solution, the wall body of the outer shell is made of carbon steel, giving the shell advantages such as high strength, low manufacturing cost, and good machinability. A first protective layer made of stainless steel is provided on the outer side of the wall body. Stainless steel includes nickel and chromium. The chromium in the stainless steel can form an extremely thin but very strong and dense chromium oxide (Cr2O3) film on the surface of the first protective layer. This oxide film is formed due to the reaction of chromium with oxygen in the environment, spontaneously forming a passivation layer on the stainless steel surface. The passivation layer can prevent further oxidation of the stainless steel base metal, possessing self-healing ability, a dense structure, and passivation effect. It can effectively block the penetration of oxygen and water molecules into the stainless steel base and the wall body, thereby preventing the stainless steel base metal and the wall body from contacting corrosive media in the environment. The chromium oxide film structure of the stainless steel is very dense, without gaps, effectively blocking the penetration of oxygen and water molecules into the stainless steel base, thereby preventing the stainless steel base metal and the wall body from contacting corrosive media in the environment. Furthermore, the rust-proof layer of stainless steel has self-healing capabilities. Even if the surface is scratched or worn, chromium can react with oxygen in the environment to reform a protective passivation film. Therefore, including stainless steel in the first protective layer reduces the risk of rust on the casing, extends the service life of the outer shell, and improves its reliability, thereby improving the reliability and extending the lifespan of the battery cells. Moreover, stainless steel is a more cost-effective material for the first protective layer. A nickel weight percentage of 2% or higher in stainless steel improves the corrosion resistance, mechanical properties, and processing performance of the first protective layer; a nickel weight percentage of less than or equal to 20% reduces its cost. A chromium weight percentage of 10% or higher in stainless steel improves the corrosion resistance, wear resistance, and mechanical properties of the first protective layer; a chromium weight percentage of less than or equal to 26% further reduces its cost.

[0006] In some embodiments of the first aspect of this application, the wall thickness of the wall body is greater than the thickness of the first protective layer.

[0007] In the above technical solution, by making the wall thickness of the outer casing greater than the thickness of the first protective layer, the outer casing wall has higher strength, thereby giving the outer casing higher mechanical properties, which in turn gives the battery cell better mechanical properties. The thinner thickness of the first protective layer reduces the space occupied by the first protective layer, which helps to reduce the volume of the battery cell and increase the volumetric energy density.

[0008] In some embodiments of the first aspect of this application, the wall thickness of the wall body is H, the thickness of the first protective layer is M, and 0.02≤H / (H+M)≤0.4.

[0009] In the above technical solution, by M / (H+M)≥0.02, the thickness of the first protective layer is relatively large, which enables the first protective layer to effectively protect the wall body, reduce the risk of wall body rusting, improve the reliability of the shell, and thus improve the reliability of the battery cell. By M / (H+M)≤0.4, the thickness of the first protective layer can be controlled, reducing the space occupied by the first protective layer, which is beneficial to reducing the weight of the battery cell and improving the volumetric energy density of the battery cell. Therefore, 0.02≤M / (H+M)≤0.4 makes the battery cell have high reliability and volumetric energy density.

[0010] In some embodiments of the first aspect of this application, 0.4mm ≤ H + M ≤ 3mm.

[0011] In the above technical solution, by H+M≥0.4mm, the thickness of the wall formed by the first protective layer and the wall body is relatively large, which makes the wall have better strength and improves the reliability of the battery cell; H+M≤3mm, the thickness of the wall is reduced, thereby reducing the space occupied by the wall, which is conducive to improving the volumetric energy density of the battery cell. Therefore, 0.4mm≤H+M≤3mm makes the battery cell have high reliability and volumetric energy density.

[0012] In some embodiments of the first aspect of this application, 0.05mm ≤ M ≤ 0.4mm.

[0013] In the above technical solution, by M≥0.05mm, the thickness of the first protective layer is relatively large, thereby enabling the first protective layer to effectively protect the wall body, reduce the risk of wall body rusting, and improve the reliability of the battery cell; by M≤0.4mm, the thickness of the first protective layer can be controlled, reducing the space occupied by the first protective layer, which is beneficial to reducing the weight of the battery cell and improving the volumetric energy density of the battery cell. Therefore, 0.05mm≤M≤0.4mm enables the battery cell to have high reliability and volumetric energy density.

[0014] In some embodiments of the first aspect of this application, 0.1mm ≤ M ≤ 0.2mm.

[0015] In the above technical solution, by M≥0.1mm, the thickness of the first protective layer is increased, thereby enabling the first protective layer to effectively protect the wall body, further reducing the risk of wall body rusting, and further improving the reliability of the battery cell; by M≤0.2mm, the thickness of the first protective layer can be controlled, further reducing the space occupied by the first protective layer, which is conducive to reducing the weight of the battery cell and increasing the volumetric energy density of the battery cell. Therefore, 0.1mm≤M≤0.2mm results in the battery cell having higher reliability and volumetric energy density.

[0016] In some embodiments of the first aspect of this application, the wall portion further includes a second protective layer disposed on the inner side of the wall body and covering at least a portion of the inner surface of the wall body, the material of the second protective layer including stainless steel.

[0017] In the above technical solution, the inner surface of the wall body, made of carbon steel, is provided with a second protective layer made of stainless steel. Chromium in the stainless steel can form an extremely thin but very strong and dense chromium oxide film on the surface of the second protective layer. This oxide film can form spontaneously due to the reaction of chromium with oxygen in the environment, creating a passivation layer on the stainless steel surface. This passivation layer prevents further oxidation of the base metal, possessing self-healing capabilities, a dense structure, and passivation effects. It effectively blocks the penetration of oxygen and water molecules into the stainless steel substrate and the wall body, thereby preventing the stainless steel substrate metal and the wall body from contacting the corrosive medium inside the battery cell. The chromium oxide film structure of the stainless steel is very dense and without gaps, effectively blocking the penetration of the corrosive medium inside the battery cell into the stainless steel substrate, thus preventing the stainless steel substrate metal and the wall body from contacting the corrosive medium inside the battery cell. In addition, the rust-proof layer of stainless steel has self-healing ability. Even if the surface is scratched or worn, chromium can react with oxygen in the environment again to reform a protective passivation film. Therefore, the material of the second protective layer, including stainless steel, can reduce the risk of corrosion of the wall body by substances inside the shell, extend the service life of the shell and improve the reliability of the shell, thereby improving the reliability of the battery cell and extending the reliability of the battery cell.

[0018] In some embodiments of the first aspect of this application, the wall thickness of the wall body is greater than the thickness of the second protective layer.

[0019] In the above technical solution, by making the wall thickness of the main body greater than the thickness of the second protective layer, the main body possesses higher strength, thereby giving the battery cell better mechanical properties. The smaller thickness of the second protective layer reduces the space it occupies inside the main body, which is beneficial for improving the energy density of the battery cell.

[0020] In some embodiments of the first aspect of this application, the wall thickness of the wall body is H, the thickness of the first protective layer is M, the thickness of the second protective layer is N, and 0.04≤(M+N) / (H+M+N)≤0.5.

[0021] In the above technical solution, by having (M+N) / (H+M+N)≥0.04, the sum of the thicknesses of the first and second protective layers is relatively large, thereby enabling the second and first protective layers to effectively protect the inner and outer sides of the battery body, respectively, reducing the risk of corrosion and rust on the battery body, improving the reliability of the outer shell, and thus improving the reliability of the battery cell. By having (M+N) / (H+M+N)≤0.5, the thicknesses of the first and second protective layers can be controlled, reducing the space occupied by the first and second protective layers, which is beneficial to reducing the weight of the battery cell and improving the volumetric energy density of the battery cell. Therefore, 0.04≤(M+N) / (H+M+N)≤0.5 results in the battery cell having high reliability and volumetric energy density.

[0022] In some embodiments of the first aspect of this application, 0.4mm ≤ H + M + N ≤ 3mm.

[0023] In the above technical solution, by H+M+N≥0.4mm, the wall formed by the first protective layer, the second protective layer and the wall body has good strength, which improves the reliability of the battery cell; by H+M+N≤3mm, the thickness of the wall formed by the first protective layer, the second protective layer and the wall body is reduced, thereby reducing the space occupied by the wall, which is beneficial to improving the volumetric energy density of the battery cell. Therefore, 0.4mm≤H+M+N≤3mm makes the battery cell have high reliability and volumetric energy density.

[0024] In some embodiments of the first aspect of this application, 0.05mm ≤ N ≤ 0.4mm.

[0025] In the above technical solution, by using N≥0.05mm, the thickness of the second protective layer is relatively large, thereby enabling the second protective layer to effectively protect the inner side of the wall body, reducing the risk of the wall body being corroded by substances inside the outer shell, and improving the reliability of the battery cell; by using N≤0.4mm, the thickness of the second protective layer can be controlled, reducing the space occupied by the second protective layer on the inner side of the wall body, and improving the energy density of the battery cell. Therefore, 0.05mm≤N≤0.4mm results in the battery cell having high reliability and volumetric energy density.

[0026] In some embodiments of the first aspect of this application, 0.1mm ≤ N ≤ 0.2mm.

[0027] In the above technical solution, by using N≥0.1mm, the thickness of the second protective layer is increased, thereby enabling the second protective layer to effectively protect the inner side of the wall body, further reducing the risk of corrosion of the wall body by substances inside the outer shell, and further improving the reliability of the battery cell; by using N≤0.2mm, the thickness of the second protective layer can be controlled, further reducing the space occupied by the second protective layer inside the wall body, and improving the volumetric energy density of the battery cell. Therefore, 0.1mm≤N≤0.2mm results in the battery cell having higher reliability and volumetric energy density.

[0028] In some embodiments of the first aspect of this application, the nickel content is 8% to 10.5% by weight, and the chromium content is 17.5% to 19.5% by weight.

[0029] In the above technical solutions, having a nickel weight ratio of 8% or higher in the stainless steel helps to further improve the corrosion resistance, mechanical properties, and processing performance of the first protective layer; having a nickel weight ratio of 10.5% or lower helps to further reduce the cost of the first protective layer. Similarly, having a chromium weight ratio of 17.5% or higher in the stainless steel helps to further improve the corrosion resistance, wear resistance, and mechanical properties of the first protective layer; having a chromium weight ratio of 19.5% or lower helps to further reduce the cost of the first protective layer.

[0030] In some embodiments of the first aspect of this application, the housing includes a shell and an end cap, the shell having an opening, the end cap sealing the opening, the end cap being the wall portion and / or at least a portion of the wall of the shell being the wall portion.

[0031] In the above technical solution, if the end cap of the outer casing is a wall portion, then the end cap includes a first protective layer made of stainless steel. This reduces the risk of rust on the end cap, extending the service life and improving the reliability of the outer casing, thereby improving and extending the reliability of the individual battery cells. If at least a portion of the wall of the outer casing is a wall portion, then the wall of the casing includes a first protective layer made of stainless steel. This reduces the risk of rust on the wall of the casing, extending the service life and improving the reliability of the outer casing, thereby improving and extending the reliability of the individual battery cells.

[0032] In some embodiments of the first aspect of this application, the electrode assembly includes a first tab, and the battery cell further includes a current collector connected to the first tab. The current collector is welded to the wall portion to form a solder mark, a portion of which is located on the wall body.

[0033] In the above technical solution, the current collector is connected to the first tab and welded to the wall. That is, the outer casing and the first tab are electrically connected through the current collector, and the outer casing forms one output electrode of the battery cell. Connecting the first tab and the wall through the current collector improves current carrying capacity and facilitates electrical connection between the second tab and the outer casing. A portion of the weld mark formed by the welding connection between the current collector and the wall is located on the wall body. The wall body is made of carbon steel, which has good conductivity, helping to reduce the resistance of the battery cell, reduce losses, and increase the charging rate. Stainless steel has good rust resistance. Therefore, when the outer casing serves as one output electrode of the battery cell, the wall body is made of carbon steel, and the first protective layer is made of stainless steel, giving the battery cell casing both good conductivity and good reliability.

[0034] In some embodiments of the first aspect of this application, the housing includes a shell and an end cap, the shell having an opening, the end cap sealing the opening, the end cap being the wall portion, the end cap being welded to the current collector and forming the weld mark.

[0035] In the above technical solution, the end cap is a wall portion, and the end cap is welded to the current collector to form a weld mark, which facilitates the assembly of battery cells.

[0036] In some embodiments of the first aspect of this application, the battery cell further includes an electrode terminal disposed on the housing and insulated from the housing; the electrode assembly includes a second tab, the first tab and the second tab having opposite polarities; the second tab is electrically connected to the electrode terminal.

[0037] In the above technical solution, the electrode terminal is electrically connected to the second tab of the electrode assembly, so the shell and the electrode terminal respectively form two output poles with opposite polarities of the battery cell. The electrode terminal is set in the shell, which facilitates the connection of the first tab and the second tab to the shell and the electrode terminal respectively, reducing the risk of interference.

[0038] In some embodiments of the first aspect of this application, at least a portion of the wall of the housing is the wall portion, the housing includes a side wall and a bottom wall, the side wall is disposed around the electrode assembly, the bottom wall is disposed opposite to the end cap, and the electrode terminal is disposed on the bottom wall.

[0039] In the above technical solution, the bottom wall and the end cap are arranged opposite each other, and the electrode terminal is arranged on the bottom wall. The connection position of the first electrode tab and the end cap and the connection position of the second electrode tab and the electrode terminal are respectively located on opposite sides of the electrode assembly, which facilitates the welding connection of the first electrode tab and the end cap, and facilitates the connection of the second electrode tab and the electrode terminal.

[0040] In some embodiments of the first aspect of this application, the end cap is the wall portion, and the end cap is welded to the housing.

[0041] In the above technical solution, the end cap is welded to the shell, which makes the connection stability of the end cap and the shell high and helps to improve the sealing performance of the end cap and the shell, thereby improving the reliability of the battery cell.

[0042] Secondly, embodiments of this application provide a battery device, which includes the battery cell provided in any embodiment of the first aspect.

[0043] In the above technical solutions, the battery cell provided in any embodiment of the first aspect has high reliability, and the battery device including the battery cell also has good reliability.

[0044] Thirdly, embodiments of this application provide an electrical device, which includes a battery cell provided in any embodiment of the first aspect or a battery device provided in any embodiment of the second aspect.

[0045] In the above technical solutions, the battery cell provided in any embodiment of the first aspect and the battery device provided in any embodiment of the second aspect have high reliability, which can improve the power supply reliability of the power-consuming device powered by the battery cell or the battery device. Attached Figure Description

[0046] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments;

[0048] Figure 2 Exploded views of battery devices provided in some embodiments of this application;

[0049] Figure 3 Exploded views of a single battery cell provided in some embodiments of this application;

[0050] Figure 4 Cross-sectional views of a battery cell provided in some embodiments of this application;

[0051] Figure 5 for Figure 4 Enlarged view at point A1;

[0052] Figure 6 Cross-sectional views of a battery cell provided for other embodiments of this application;

[0053] Figure 7for Figure 6 Enlarged view at point A2;

[0054] Figure 8 A cross-sectional view of a battery cell provided in some embodiments of this application;

[0055] Figure 9 for Figure 8 Enlarged view at point A3;

[0056] Figure 10 A cross-sectional view of a battery cell provided for some embodiments of this application;

[0057] Figure 11 for Figure 10 Enlarged view at A4 in the middle.

[0058] Icons: 1000 - Vehicle; 100 - Battery assembly; 10 - Housing; 11 - First housing; 12 - Second housing; 20 - Battery cell; 21 - Casing; 211 - Wall; 2111 - Wall body; 2112 - First protective layer; 2113 - Second protective layer; 212 - Housing; 2121 - Opening; 2122 - Side wall; 2123 - Bottom wall; 213 - End cap; 22 - Electrode assembly; 221 - First tab; 222 - Second tab; 23 - Electrode terminal; 24 - Current collector; 25 - Insulator; 200 - Controller; 300 - Motor. Detailed Implementation

[0059] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0060] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

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

[0062] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0063] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0064] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0065] In this application, "multiple" means two or more (including two).

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, it can be aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, or titanium, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0072] As an example, the positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials in battery cells may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxide may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds.

[0073] In some embodiments, the positive electrode can be a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloys, etc. When foamed metal is used as the positive electrode, the surface of the foamed metal may or may not contain a positive electrode active material. As an example, lithium source material, potassium metal, or sodium metal can also be filled and / or deposited within the foamed metal, where the lithium source material is lithium metal and / or a lithium-rich material.

[0074] In some embodiments, the negative electrode can be a negative electrode sheet, and the negative electrode sheet can include a negative current collector.

[0075] As an example, the negative electrode current collector can be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, it can be aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, or titanium, etc. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloys, etc. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0076] As an example, the negative electrode sheet may include a negative current collector and a negative active material disposed on at least one surface of the negative current collector.

[0077] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0078] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials in battery cells may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0079] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0080] In some embodiments, the separator is a separator membrane. The separator membrane can be any known porous structure separator membrane with good chemical and mechanical stability.

[0081] As an example, the material of the separator may include at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different. The separator may be a separate component located between the positive and negative electrodes, or it may be attached to the surfaces of the positive and negative electrodes.

[0082] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0083] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The electrolyte can be liquid, gel-like, or solid. Liquid electrolytes include electrolyte salts and solvents.

[0084] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0085] In some embodiments, the solvent may include at least one selected from ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may include one or more selected from ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0086] Among them, the gel electrolyte includes a polymer as the electrolyte backbone network, combined with an ionic liquid - lithium salt.

[0087] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0088] As an example, polymer solid electrolytes can be polyethers (polyoxyethylene), polysiloxanes, polycarbonates, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids-lithium salts, cellulose, etc.

[0089] As an example, inorganic solid electrolytes may include one or more of the following: oxide solid electrolytes (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON thin film), sulfide solid electrolytes (crystalline lithium superconducting ion conductor (lithium germanium phosphate sulfide, silver sulfide germanium ore), amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0090] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0091] In some embodiments, the electrode assembly is a wound structure. The positive electrode and the negative electrode are wound into a wound structure.

[0092] In some implementations, the electrode assembly is a stacked structure.

[0093] As an example, multiple positive and negative electrode plates can be set, and multiple positive and multiple negative electrode plates can be stacked alternately.

[0094] 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.

[0095] As an example, both the positive and negative electrode sheets are folded to form multiple stacked folded segments.

[0096] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0097] As an example, the separator can be continuously arranged between any adjacent positive or negative electrode plates by folding or rolling.

[0098] In some embodiments, the electrode assembly can be cylindrical, flat, or polygonal, etc.

[0099] In some embodiments, the electrode assembly is provided with tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0100] 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.

[0101] As an example, a battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include prismatic battery cells, blade-shaped battery cells, and multi-prismatic battery cells, such as hexagonal prismatic battery cells.

[0102] The battery device mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells, which are connected in series, parallel, or mixed connections via a busbar.

[0103] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells; as an example, a battery cell assembly can be a battery module, which is formed by arranging multiple battery cells and fixing them together to form an independent module.

[0104] As an example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0105] In some embodiments, the battery device may be a battery pack, which may include a housing and one or more individual battery cell assemblies housed within the housing.

[0106] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0107] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0108] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0109] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0110] As an example, the housing can be part of the vehicle's chassis structure. For instance, the housing's roof can be at least part of the vehicle's floor, or the housing's frame can be at least part of the vehicle's crossbeams and longitudinal beams.

[0111] In some embodiments, the battery device refers to an energy storage device, which includes a housing 10, with a door on at least one side. The energy storage device includes energy storage containers, energy storage cabinets, etc.

[0112] A battery cell consists of a casing and electrode assemblies. The electrode assemblies are housed within the casing, which is made of carbon steel. Carbon steel is prone to rusting in humid or oxygen-containing environments. Related technologies employ anti-corrosion measures such as nickel plating on the outer surface of the casing. However, gaps still exist in the nickel plating layer, allowing the casing to corrode further, thus reducing the reliability and shortening the battery cell's lifespan. Applying a nickel plate to the casing surface would be more expensive.

[0113] Based on the above considerations, in order to improve the reliability of the battery cell and extend its service life, this application provides a battery cell, which includes an electrode assembly and a housing; the electrode assembly is housed within the housing, and the housing includes a wall portion, which includes a wall body and a first protective layer. The first protective layer is disposed on the outside of the wall body and covers at least a portion of the outer surface of the wall body. The wall body is made of carbon steel, and the first protective layer is made of stainless steel. The stainless steel includes nickel and chromium, with nickel accounting for 2% to 20% by weight and chromium accounting for 10% to 26% by weight.

[0114] The outer casing's walls are made of carbon steel, giving it advantages such as high strength, low manufacturing cost, and good machinability. A first protective layer made of stainless steel is applied to the outer side of the walls. Stainless steel contains nickel and chromium. The chromium in the stainless steel forms an extremely thin but very strong and dense chromium oxide film on the surface of the first protective layer. This oxide film forms spontaneously on the stainless steel surface due to the reaction of chromium with oxygen in the environment. This passivation layer prevents further oxidation of the stainless steel base metal, possessing self-healing capabilities, a dense structure, and passivation effects. It effectively blocks the penetration of oxygen and water molecules into the stainless steel base metal and the walls, thus preventing contact between the stainless steel base metal and the walls and corrosive media in the environment. The chromium oxide film structure of the stainless steel is extremely dense, without gaps, effectively blocking the penetration of oxygen and water molecules into the stainless steel base metal, thereby preventing contact between the stainless steel base metal and the walls and corrosive media in the environment. Furthermore, the rust-proof layer of stainless steel has self-healing capabilities. Even if the surface is scratched or worn, chromium can react with oxygen in the environment to reform a protective passivation film. Therefore, the use of stainless steel as the material for the first protective layer reduces the risk of rust on the casing, extends the service life of the casing, and improves its reliability, thereby improving the reliability and extending the lifespan of the battery cells. Moreover, the use of stainless steel for the first protective layer results in lower costs.

[0115] A nickel content of 2% or higher in stainless steel improves the corrosion resistance, mechanical properties, and processing performance of the first protective layer; a nickel content of less than 20% or higher reduces the cost of the first protective layer. Similarly, a chromium content of 10% or higher in stainless steel improves the corrosion resistance, wear resistance, and mechanical properties of the first protective layer; a chromium content of less than 26% or higher reduces the cost of the first protective layer.

[0116] 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.

[0117] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0118] Please refer to Figure 1 , Figure 1This is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of this application. A battery device 100 is disposed inside the vehicle 1000, and the battery device 100 may be located at the bottom, front, or rear of the vehicle 1000. The battery device 100 can be used to power the vehicle 1000; for example, the battery device 100 can serve as the operating power source for the vehicle 1000.

[0119] The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery device 100 to supply power to the motor 300, for example, for the power needs of the vehicle 1000 during startup, navigation and driving.

[0120] In some embodiments of this application, the battery device 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0121] Please refer to Figure 2 , Figure 2 The exploded view of a battery device 100 provided in some embodiments of this application shows that the battery device 100 may include a housing 10 and a battery cell 20, wherein the housing 10 is used to house the battery cell 20.

[0122] The housing 10 has an enclosed space inside for accommodating the battery cells 20. The housing 10 can have various structures. In some embodiments, the housing 10 may include a first housing 11 and a second housing 12, which are interlocked. The first housing 11 and the second housing 12 can have various shapes, such as cuboids or cylinders. The first housing 11 can be a hollow structure open on one side, and the second housing 12 can also be a hollow structure open on one side. The open side of the second housing 12 interlocks with the open side of the first housing 11, thus forming a housing 10 with an enclosed space. Alternatively, the first housing 11 can be a hollow structure open on one side, and the second housing 12 can be a plate-like structure, with the second housing 12 interlocked with the open side of the first housing 11, thus forming a housing 10 with an accommodating space.

[0123] In the battery device 100, there can be one or more battery cells 20. If there are multiple battery cells 20, they can be connected in series, parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells 20 are connected in both series and parallel. Alternatively, multiple battery cells 20 can be first connected in series, parallel, or in a mixed configuration to form a battery module, and then multiple battery modules can be connected in series, parallel, or in a mixed configuration to form a whole, which is then housed within the housing 10. Another option is that all battery cells 20 can be directly connected in series, parallel, or in a mixed configuration, and then the whole consisting of all battery cells 20 is housed within the housing 10.

[0124] In some embodiments, the battery device 100 may further include a busbar (not shown in the figure), through which multiple battery cells 20 can be electrically connected to each other to achieve series, parallel, or mixed connection of multiple battery cells 20. The busbar can be a metal conductor, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0125] Please refer to Figure 3 , Figure 3 This is an exploded view of a battery cell 20 provided in some embodiments of this application. The battery cell 20 may include a housing 21 and an electrode assembly 22, the electrode assembly 22 being housed within the housing 21.

[0126] In some embodiments, the housing 21 may include a housing 212 and an end cap 213, the housing 212 having an opening 2121, and the end cap 213 covering the opening 2121 of the housing 212. Here, "covering" refers to covering or closing, and can be either sealed or unsealed.

[0127] The housing 212 is a component used to house the electrode assembly 22. The housing 212 can be a hollow structure with an opening 2121 at one end, or it can be a hollow structure with openings 2121 at both opposite ends. The housing 212 can have various shapes, such as a cylinder or a cuboid. The electrode assembly 22 can be partially or completely located within the housing 212.

[0128] End cap 213 and housing 212 together define a receiving space for accommodating electrode assembly 22 and other components. End cap 213 can be connected to housing 212 by welding, roll sealing, or other methods to close opening 2121 of housing 212. The shape of end cap 213 can be adapted to the shape of housing 212. For example, if housing 212 is a cuboid structure, end cap 213 can be a rectangular plate structure adapted to housing 212; or if housing 212 is a cylindrical structure, end cap 213 can be a circular plate structure adapted to housing 212.

[0129] In an embodiment where the housing 212 has an opening 2121 at one end, one end cap 213 may be provided accordingly. In an embodiment where the housing 212 has openings 2121 at both opposite ends, two end caps 213 may be provided accordingly. The two end caps 213 respectively close the two openings 2121 of the housing 212, and the two end caps 213 and the housing 212 together define the receiving space.

[0130] like Figure 3 , Figure 4As shown, in some embodiments, the battery cell 20 may further include electrode terminals 23, which are disposed on the housing 21. The electrode terminals 23 are used for electrical connection with the tabs of the electrode assembly 22 to input or output electrical energy from the battery cell 20. The electrode terminals 23 may be disposed on the housing 212 of the housing 21 or on the end cap 213 of the housing 21. The electrode terminals 23 and the tabs may be directly connected, for example, by welding the electrode terminals 23 to the tabs. The electrode terminals 23 and the tabs may also be indirectly connected, for example, through a current collector 24. The current collector 24 may be a metallic conductor, such as copper, iron, aluminum, steel, or aluminum alloy.

[0131] As an example, such as Figure 3 and Figure 4 As shown, one end of the housing 212 forms an opening 2121, and there is one end cap 213 in the housing 21, which closes one opening 2121 of the housing 212. An electrode terminal 23 is provided on the bottom wall 2123 of the housing 212. The end of the electrode assembly 22 facing the electrode terminal 23 has a second tab 222, which is electrically connected to the electrode terminal 23. The end of the electrode assembly 22 facing the end cap 213 has a first tab 221, which is electrically connected to the end cap 213.

[0132] like Figure 4 , Figure 5 As shown, in some embodiments, the battery cell 20 includes an electrode assembly 22 and a housing 21; the electrode assembly 22 is housed within the housing 21, and the housing 21 includes a wall portion 211, the wall portion 211 including a wall body 2111 and a first protective layer 2112, the first protective layer 2112 being disposed on the outside of the wall body 2111 and covering at least a portion of the outer surface of the wall body 2111, the wall body 2111 being made of carbon steel, and the first protective layer 2112 being made of stainless steel.

[0133] The wall portion 211 may be part of or all of the wall of the housing 21. At least a portion of the wall of the housing 212 is the wall portion 211, and / or the end cap 213 is the wall portion 211.

[0134] The wall body 2111 is the main structure of the wall portion 211 of the outer shell 21, and plays a decisive role in the structural strength of the wall portion 211 of the outer shell 21. The wall bodies 2111 of all the wall portions 211 of the outer shell 21 can collectively define the space for accommodating the electrode assembly 22.

[0135] The wall body 2111 is made of carbon steel. For example, the wall body 2111 of the shell 212 is made of carbon steel, or the wall body 2111 of the end cap 213 is made of carbon steel, or both the wall body 2111 of the shell 212 and the wall body 2111 of the end cap 213 are made of carbon steel. The wall body 2111 may be made of carbon steel in some areas or in all areas.

[0136] Carbon steel has advantages such as high strength, high machinability, low manufacturing cost, and strong weldability.

[0137] Stainless steel possesses excellent rust and corrosion resistance. This resistance relies on a chromium-rich oxide film (passivation film) that forms on its surface. This oxide film effectively isolates the metal from the external environment, thus preventing further corrosion.

[0138] Specifically, stainless steel includes nickel and chromium, with nickel accounting for 2% to 20% by weight and chromium accounting for 10% to 26% by weight.

[0139] The main components of stainless steel include elements such as iron, chromium, and nickel, with chromium being the key element. When the chromium content reaches a certain level, chromium reacts with oxygen in the medium to form a dense oxide film on the steel surface. This film has the ability to self-repair; once damaged, chromium will react with oxygen in the medium to regenerate a passivation film, continuing to provide protection.

[0140] For example, the weight percentage of nickel is 2%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, etc.

[0141] Chromium content by weight is 10%, 12%, 14%, 15%, 18%, 20%, 22%, 24%, 26%, etc.

[0142] The first protective layer 2112 may cover all or part of the outer surface of the wall body 2111 of the wall portion 211.

[0143] The entire area of ​​the wall body 2111 is made of carbon steel, or a portion thereof. The first protective layer 2112 can be provided corresponding to the carbon steel areas of the wall body 2111; in other words, the outer surface of the carbon steel areas of the wall body 2111 is covered by the first protective layer 2112. Of course, in either the embodiment where the entire area of ​​the wall body 2111 is made of carbon steel or where a portion thereof is made of carbon steel, the outer surface of the wall body 2111 can be completely covered by the first protective layer 2112.

[0144] The first protective layer 2112 can be a stainless steel coating, stainless steel plating, stainless steel plate, etc., on the outside of the wall body 2111.

[0145] There are several ways to set the first protective layer 2112 on the outer surface of the wall body 2111. For example, the first protective layer 2112 can be bonded to the outer surface of the wall body 2111 by an adhesive layer or coated on the outer surface of the wall body 2111.

[0146] In some embodiments, the first protective layer 2112 is thermally bonded to the outer surface of the wall body 2111.

[0147] In this embodiment, a stainless steel plate and a carbon steel plate are thermally bonded together to form an integral substrate. The substrate is then stretched to form a first protective layer 2112 on the stainless steel plate and a wall body 2111 on the carbon steel plate. Since the first protective layer 2112 is thermally bonded to the outer surface of the wall body 2111, no other structural connection is needed between the first protective layer 2112 and the wall body 2111. This reduces the weight of the wall portion 211 formed by the first protective layer 2112 and the wall body 2111, which in turn helps to reduce the weight of the outer casing 21 and improve the energy density of the battery cell 20.

[0148] The wall body 2111 of the outer shell 21 is made of carbon steel, giving the outer shell 21 advantages such as high strength, low manufacturing cost, and good machinability. A first protective layer 2112 made of stainless steel is provided on the outer side of the wall body 2111. Stainless steel includes nickel and chromium. The chromium in the stainless steel can form an extremely thin but very strong and dense chromium oxide (Cr2O3) film on the surface of the first protective layer 2112. This oxide film is formed due to the reaction of chromium with oxygen in the environment, spontaneously forming a passivation layer on the stainless steel surface. The passivation layer can prevent further oxidation of the stainless steel base metal, possessing self-healing ability, a dense structure, and passivation effect. It can effectively block the penetration of oxygen and water molecules into the stainless steel base and the wall body, thereby preventing the stainless steel base metal and the wall body from contacting corrosive media in the environment. The chromium oxide film structure of the stainless steel is very dense and without gaps, effectively blocking the penetration of oxygen and water molecules into the stainless steel base, thereby preventing the stainless steel base metal and the wall body 2111 from contacting corrosive media in the environment. Furthermore, the rust-proof layer of stainless steel has self-healing capabilities. Even if the surface is scratched or worn, chromium can react with oxygen in the environment to reform a protective passivation film. Therefore, the first protective layer 2112 is made of stainless steel, which reduces the risk of rust on the wall body 2111, extends the service life of the outer casing 21, and improves the reliability of the outer casing 21, thereby improving the reliability and extending the lifespan of the battery cell 20. Moreover, the first protective layer 2112 is made of stainless steel, resulting in lower costs.

[0149] A nickel content of 2% or more in the stainless steel improves the corrosion resistance, mechanical properties, and processing performance of the first protective layer 2112. A nickel content of less than or equal to 20% in the stainless steel reduces the cost of the first protective layer 2112. A chromium content of 10% or more in the stainless steel improves the corrosion resistance, wear resistance, and mechanical properties of the first protective layer 2112; a chromium content of less than or equal to 26% in the stainless steel reduces the cost of the first protective layer 2112.

[0150] In some embodiments, the wall thickness of the wall body 2111 is greater than the thickness of the first protective layer 2112.

[0151] The wall thickness of the wall body 2111 is the distance between the inner and outer surfaces of the wall body 2111 in the thickness direction of the wall portion 211. For example, the wall thickness of the wall body 2111 of the bottom wall 2123 of the shell 212 is the distance between the inner and outer surfaces of the wall body 2111 of the bottom wall 2123 along the thickness direction of the bottom wall 2123; the wall thickness of the wall body 2111 of the side wall 2122 of the shell 212 is the distance between the inner and outer surfaces of the wall body 2111 of the side wall 2122 along the thickness direction of the side wall 2122.

[0152] Understandably, the wall thickness at any location of the wall body 2111 is greater than the thickness of the first protective layer 2112.

[0153] By making the wall thickness of the outer casing 2111 greater than the thickness of the first protective layer 2112, the wall portion 211 of the outer casing 21 has higher strength, thereby giving the battery cell 20 better mechanical properties. The thinner thickness of the first protective layer 2112 reduces the space occupied by the first protective layer 2112, which is beneficial to reducing the volume of the battery cell 20 and increasing the volumetric energy density.

[0154] like Figures 4-7 As shown, in some embodiments, the wall thickness of the wall body 2111 is H, and the thickness of the first protective layer 2112 is M, where 0.02≤H / (H+M)≤0.4.

[0155] It should be noted that H is merely a symbol representing the wall thickness of the wall body 2111, and does not mean that the wall thickness of the wall body 2111 is the same at any position. For example, the wall thickness of the wall body 2111 of the side wall 2122 of the shell 212 and the wall thickness of the wall body 2111 of the bottom wall 2123 can be the same or different.

[0156] M is merely a symbol representing the thickness of the first protective layer 2112, and does not mean that the thickness of the first protective layer 2112 is the same at any location.

[0157] In the same cross-section along the thickness direction of the vertical wall portion 211, M+H is the wall thickness of the wall portion 211 at the corresponding position in that cross-section.

[0158] For example, H / (H+M) can be 0.02, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, etc.

[0159] By ensuring that M / (H+M) ≥ 0.02, the thickness of the first protective layer 2112 is relatively large, thereby enabling the first protective layer 2112 to effectively protect the wall body 2111, reduce the risk of rust on the wall body 2111, and improve the reliability of the battery cell 20. By ensuring that M / (H+M) ≤ 0.4, the thickness of the first protective layer 2112 can be controlled, reducing the space occupied by the first protective layer 2112, which helps to reduce the weight of the battery cell 20 and improve the volumetric energy density of the battery cell 20. Therefore, 0.02 ≤ M / (H+M) ≤ 0.4 results in the battery cell 20 having high reliability and volumetric energy density.

[0160] In some embodiments, 0.4mm ≤ H + M ≤ 3mm.

[0161] For example, H+M can be 0.4mm, 0.5mm, 0.8mm, 1mm, 1.2mm, 1.4mm, 1.5mm, 1.8mm, 2mm, 2.2mm, 2.4mm, 2.6mm, 2.8mm, 3mm, etc.

[0162] With H+M≥0.4mm, the thickness of the wall portion 211 formed by the first protective layer 2112 and the wall body 2111 is relatively large, which gives the wall portion 211 better strength and improves the reliability of the battery cell 20; with H+M≤3mm, the thickness of the wall portion 211 is reduced, thereby reducing the space occupied by the wall portion 211, which is beneficial to improving the volumetric energy density of the battery cell 20. Therefore, 0.4mm≤H+M≤3mm gives the battery cell 20 high reliability and volumetric energy density.

[0163] In some embodiments, 0.05mm ≤ M ≤ 0.4mm.

[0164] For example, M can be 0.05mm, 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, etc.

[0165] By ensuring M ≥ 0.05 mm, the thickness of the first protective layer 2112 is relatively large, thereby enabling the first protective layer 2112 to effectively protect the wall body 2111, reducing the risk of rust on the wall body 2111 and improving the reliability of the battery cell 20. By ensuring M ≤ 0.4 mm, the thickness of the first protective layer 2112 can be controlled, reducing the space occupied by the first protective layer 2112, which helps to reduce the weight of the battery cell 20 and improve the volumetric energy density of the battery cell 20. Therefore, 0.05 mm ≤ M ≤ 0.4 mm results in the battery cell 20 having high reliability and volumetric energy density.

[0166] Optionally, 0.1mm ≤ M ≤ 0.2mm.

[0167] For example, M can be 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.2mm, etc.

[0168] By ensuring M ≥ 0.1 mm, the thickness of the first protective layer 2112 is increased, thereby enabling the first protective layer 2112 to effectively protect the wall body 2111, further reducing the risk of rust on the wall body 2111 and further improving the reliability of the battery cell 20. By ensuring M ≤ 0.2 mm, the thickness of the first protective layer 2112 can be controlled, further reducing the space occupied by the first protective layer 2112, which helps to reduce the weight of the battery cell 20 and improve the volumetric energy density of the battery cell 20. Therefore, 0.1 mm ≤ M ≤ 0.2 mm results in the battery cell 20 having higher reliability and volumetric energy density.

[0169] like Figures 8-11 As shown, in some embodiments, the outer casing 21 further includes a second protective layer 2113, which is disposed on the inner side of the wall body 2111 and covers at least a portion of the inner surface of the wall body 2111. The material of the second protective layer 2113 includes stainless steel.

[0170] The second protective layer 2113 may cover the entire inner surface of the wall body 2111, or it may cover only a portion of the inner surface of the wall body 2111.

[0171] The second protective layer 2113 can also be provided for carbon steel. In other words, the inner surface of the area of ​​the wall body 2111 made of carbon steel is covered by the second protective layer 2113. Of course, in any embodiment where the entire area of ​​the wall body 2111 is made of carbon steel or a portion of the wall body 2111 is made of carbon steel, the outer surface of the wall body 2111 can be completely covered by the first protective layer 2112.

[0172] The second protective layer 2113 can be a stainless steel coating, stainless steel plating, stainless steel plate, etc., placed on the inner side of the wall body 2111.

[0173] There are several ways to set the second protective layer 2113 on the inner surface of the wall body 2111. For example, the second protective layer 2113 can be bonded to the inner surface of the wall body 2111 by an adhesive layer or coated on the inner surface of the wall body 2111.

[0174] In some embodiments, the second protective layer 2113 is thermally bonded to the inner surface of the wall body 2111.

[0175] In this embodiment, two stainless steel plates are thermally bonded to both sides of a carbon steel plate to form a substrate comprising a carbon steel plate and two stainless steel plates. The substrate is then stretched so that one stainless steel plate forms a first protective layer 2112, the other stainless steel plate forms a second protective layer 2113, and the carbon steel plate forms a wall body 2111.

[0176] The inner surface of the carbon steel wall body 2111 is provided with a second protective layer 2113 made of stainless steel. Chromium in the stainless steel can form an extremely thin but very strong and dense chromium oxide film on the surface of the second protective layer 2113. The formation of this oxide film may be due to the reaction of chromium with oxygen in the environment, spontaneously forming a passivation layer on the stainless steel surface. The passivation layer can prevent further oxidation of the base metal, and has self-repairing ability, dense structure and passivation effect. It can effectively block the penetration of oxygen and water molecules into the stainless steel base and the wall body 2111, thereby preventing the stainless steel base metal and the wall body 2111 from contacting the corrosive medium inside the battery cell 20. The chromium oxide film structure of the stainless steel is very dense and has no gaps, which can effectively block the penetration of the corrosive medium inside the battery cell 20 into the stainless steel base, thereby preventing the stainless steel base metal and the wall body 2111 from contacting the corrosive medium inside the battery cell 20. In addition, the rust-proof layer of stainless steel has self-healing ability. Even if the surface is scratched or worn, chromium can react with oxygen in the environment again to reform a protective passivation film. Therefore, the material of the second protective layer 2113 includes stainless steel, which can reduce the risk of corrosion of the wall body 2111 by substances inside the outer casing 21, extend the service life of the outer casing 21 and improve the reliability of the outer casing 21, thereby improving the reliability of the battery cell 20 and extending the reliability of the battery cell 20.

[0177] In some embodiments, the wall thickness of the wall body 2111 is greater than the thickness of the second protective layer 2113.

[0178] Understandably, the wall thickness at any location of the wall body 2111 is greater than the thickness of the second protective layer 2113.

[0179] By making the wall thickness of the main body 2111 greater than the thickness of the second protective layer 2113, the main body 2111 has higher strength, thereby giving the battery cell 20 better mechanical properties. The smaller thickness of the second protective layer 2113 reduces the space occupied by the second protective layer 2113 inside the main body 2111, thereby increasing the energy density of the battery cell 20.

[0180] like Figures 8-11 As shown, in some embodiments, the wall thickness of the wall body 2111 is H, the thickness of the first protective layer 2112 is M, the thickness of the second protective layer 2113 is N, and 0.04≤(M+N) / (H+M+N)≤0.5.

[0181] N is merely a symbol representing the thickness of the second protective layer 2113, and does not mean that the thickness of the second protective layer 2113 is the same at any location.

[0182] Within the same cross-section of the thickness of the vertical wall portion 211, M+N+H represents the wall thickness of the wall portion 211 at the corresponding position in that cross-section.

[0183] For example, (M+N) / (H+M+N) can be 0.04, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, etc.

[0184] By ensuring that (M+N) / (H+M+N) ≥ 0.04, the sum of the thicknesses of the first protective layer 2112 and the second protective layer 2113 is relatively large. This allows the second protective layer 2113 and the first protective layer 2112 to effectively protect the inner and outer sides of the wall body 2111, respectively, reducing the risk of corrosion and rust on the wall body 2111 and improving the reliability of the battery cell 20. By ensuring that (M+N) / (H+M+N) ≤ 0.5, the thicknesses of the first protective layer 2112 and the second protective layer 2113 can be controlled, reducing the space occupied by the first protective layer 2112 and the second protective layer 2113. This helps to reduce the weight of the battery cell 20 and improve the volumetric energy density of the battery cell 20. Therefore, 0.04 ≤ (M+N) / (H+M+N) ≤ 0.5 results in the battery cell 20 having high reliability and volumetric energy density.

[0185] In some embodiments, 0.4mm ≤ H + M + N ≤ 3mm.

[0186] For example, H+M+N can be 0.4mm, 0.5mm, 0.8mm, 1mm, 1.2mm, 1.4mm, 1.5mm, 1.8mm, 2mm, 2.2mm, 2.4mm, 2.6mm, 2.8mm, 3mm, etc.

[0187] By ensuring H+M+N≥0.4mm, the wall portion 211 formed by the first protective layer 2112, the second protective layer 2113, and the wall body 2111 has better strength, improving the reliability of the battery cell 20. By ensuring H+M+N≤3mm, the thickness of the wall portion 211 formed by the first protective layer 2112, the second protective layer 2113, and the wall body 2111 is reduced, thereby reducing the space occupied by the wall portion 211, which is beneficial to improving the volumetric energy density of the battery cell 20. Therefore, 0.4mm≤H+M+N≤3mm results in the battery cell 20 having higher reliability and volumetric energy density.

[0188] In some embodiments, 0.05mm ≤ N ≤ 0.4mm.

[0189] For example, N can be 0.05mm, 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, etc.

[0190] By ensuring N ≥ 0.05 mm, the thickness of the second protective layer 2113 is relatively large, thereby enabling the second protective layer 2113 to effectively protect the inner side of the wall body 2111, reducing the risk of corrosion of the wall body 2111 by substances inside the outer shell 21, and improving the reliability of the battery cell 20. By ensuring N ≤ 0.4 mm, the thickness of the second protective layer 2113 can be controlled, reducing the space occupied by the second protective layer 2113 in the internal space of the wall body 2111, and improving the energy density of the battery cell 20. Therefore, 0.05 mm ≤ N ≤ 0.4 mm results in the battery cell 20 having high reliability and volumetric energy density.

[0191] Optionally, 0.1mm≤N≤0.2mm.

[0192] For example, N can be 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.2mm, etc.

[0193] By ensuring N ≥ 0.1 mm, the thickness of the second protective layer 2113 is increased, thereby enabling the second protective layer 2113 to effectively protect the inner side of the wall body 2111, further reducing the risk of corrosion of the wall body 2111 by substances inside the outer shell 21, and further improving the reliability of the battery cell 20. By ensuring N ≤ 0.2 mm, the thickness of the second protective layer 2113 can be controlled, further reducing the space occupied by the second protective layer 2113 inside the wall body 2111, and improving the volumetric energy density of the battery cell 20. Therefore, 0.1 mm ≤ N ≤ 0.2 mm results in the battery cell 20 having higher reliability and volumetric energy density.

[0194] In some embodiments, nickel accounts for 8% to 10.5% by weight and chromium accounts for 17.5% to 19.5% by weight.

[0195] For example, the weight percentage of nickel is 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, etc.

[0196] The weight percentage of chromium is 17.5%, 17.8%, 17.9%, 18%, 18.2%, 18.3%, 18.5%, 18.8%, 19%, 19.2%, 19.5%, etc.

[0197] A nickel weight percentage of 8% or higher in stainless steel is beneficial for further improving the corrosion resistance, mechanical properties, and processing performance of the first protective layer 2112. A nickel weight percentage of less than or equal to 10.5% in stainless steel is beneficial for further reducing the cost of the first protective layer 2112. A chromium weight percentage of 17.5% or higher in stainless steel is beneficial for further improving the corrosion resistance, wear resistance, and mechanical properties of the first protective layer 2112; a chromium weight percentage of less than or equal to 19.5% in stainless steel is beneficial for further reducing the cost of the first protective layer 2112.

[0198] like Figures 3-11 As shown, in some embodiments, the housing 21 includes a housing 212 and an end cap 213, the housing 212 having an opening 2121, the end cap 213 sealing the opening 2121, the end cap 213 being a wall portion 211 and / or at least a portion of the wall of the housing 212 being a wall portion 211.

[0199] End cap 213 is part of the wall of housing 21, and the wall of housing 212 is part of the wall of housing 21.

[0200] like Figure 4 , Figure 5 As shown, at least a portion of the wall of the housing 212 may be a wall portion 211, that is, only the wall of the housing 212 in the wall of the outer shell 21 may include the first protective layer 2112, or only the wall of the housing 212 in the wall of the outer shell 21 may include the first protective layer 2112 and the second protective layer 2113.

[0201] It is possible that only the end cap 213 is a wall portion 211, that is, only the end cap 213 in the wall of the outer shell 21 includes the first protective layer 2112, or only the end cap 213 in the wall of the outer shell 21 includes the first protective layer 2112 and the second protective layer 2113.

[0202] Of course, such as Figure 6 , Figure 7 as well as Figure 10 , Figure 11 As shown, at least a portion of the wall of the housing 212 and the end cap 213 are both wall portions 211.

[0203] like Figure 6 , Figure 7 as well as Figure 10 , Figure 11 As shown, the outer surface of the wall body 2111 of the end cap 213 is completely covered by the first protective layer 2112, further reducing the risk of rust on the end cap 213. Figure 10 and Figure 11 As shown, the inner surface of the wall body 2111 of the end cap 213 is completely covered by the second protective layer 2113, further reducing the risk of corrosion of the end cap 213 by substances inside the outer shell 21.

[0204] The housing 212 includes a side wall 2122 and a bottom wall 2123. The side wall 2122 surrounds the electrode assembly 22, and the bottom wall 2123 is disposed opposite to the end cap 213. One end of the side wall 2122 is connected to the bottom wall 2123, and one end of the side wall 2122 forms an opening 2121. The end cap 213 covers the opening 2121 and is disposed opposite to it. The side wall 2122 and the bottom wall 2123 can be separately disposed and connected. Alternatively, the side wall 2122 and the bottom wall 2123 can be integrally formed.

[0205] In embodiments where at least a portion of the wall of the housing 212 is a wall portion 211, the sidewall 2122 may be a wall portion 211, meaning the sidewall 2122 of the housing 212 includes a wall body 2111 and a first protective layer 2112, or the sidewall 2122 of the housing 212 includes a wall body 2111, a first protective layer 2112, and a second protective layer 2113; alternatively, the bottom wall 2123 of the housing 212 may be a wall portion 211, meaning the bottom wall 2123 includes a wall body 2111 and a first protective layer 2112, or the bottom wall 2123 of the housing 212 includes a wall body 2111, The first protective layer 2112 and the second protective layer 2113; or the side wall 2122 and the bottom wall 2123 of the shell 212 can both be wall portions 211, the side wall 2122 of the shell 212 includes a wall body 2111 and a tab of the first protective layer 2112, or the side wall 2122 of the shell 212 includes a wall body 2111, a first protective layer 2112 and a second protective layer 2113 and the bottom wall 2123 includes a wall body 2111 and a first protective layer 2112, or the bottom wall 2123 includes a wall body 2111, a first protective layer 2112 and a second protective layer 2113.

[0206] Figure 4 , Figure 5 The diagram shows a case where the sidewalls 2122 and bottomwalls 2123 of the housing 212 are both wall portions 211, and both the sidewalls 2122 and bottomwalls 2123 of the housing 212 include a wall body 2111 and a first protective layer 2112.

[0207] Figure 8 , Figure 9The diagram shows that the sidewalls 2122 and bottomwalls 2123 of the housing 212 are both wall portions 211, and the sidewalls 2122 and bottomwalls 2123 of the housing 212 each include a wall body 2111, a first protective layer 2112, and a second protective layer 2113.

[0208] If the end cap 213 of the outer casing 21 is a wall portion 211, then the end cap 213 includes a first protective layer 2112 made of stainless steel. The end cap 213 has a low risk of rusting, which can extend the service life and improve the reliability of the outer casing 21, thereby improving the reliability and extending the reliability of the battery cell 20. If at least a portion of the wall of the housing 212 of the outer casing 21 is a wall portion 211, then the wall of the housing 212 includes a first protective layer 2112 made of stainless steel. The wall of the housing 212 has a low risk of rusting, which can extend the service life and improve the reliability of the outer casing 21, thereby improving the reliability and extending the reliability of the battery cell 20.

[0209] In some embodiments, the housing 212 is stretched from a substrate. Exemplarily, in an embodiment where all walls 211 of the housing 212 include a wall body 2111 and a first protective layer 2112, the substrate includes a carbon steel layer and a stainless steel layer, wherein the carbon steel layer forms the wall body 2111 and the stainless steel layer forms the first protective layer 2112 by stretching the substrate.

[0210] In an embodiment where all walls 211 of the housing 212 include a wall body 2111, a first protective layer 2112, and a second protective layer 2113, the substrate includes a carbon steel layer and stainless steel layers respectively disposed on both sides of the carbon steel layer. By stretching the substrate, the carbon steel layer forms the wall body 2111, and the two stainless steel layers respectively form the first protective layer 2112 and the second protective layer 2113.

[0211] The shell 212 is formed by stretching the base material, which is a simple forming method that helps improve production efficiency. It also makes the shell 212 structurally strong, improves the reliability of the outer shell 21, and thus improves the reliability of the battery cell 20.

[0212] The stainless steel and carbon steel layers of the substrate can be formed from stainless steel plates and carbon steel plates. Stainless steel plates have smaller microstructure gaps and better rust and corrosion resistance.

[0213] like Figure 7 , Figure 11 As shown, in some embodiments, the electrode assembly 22 includes a first tab 221, and the battery cell 20 also includes a current collector 24. The current collector 24 is connected to the first tab 221 and welded to the wall portion 211 to form a solder mark. A portion of the solder mark is located on the wall body 2111.

[0214] The current collector 24 is connected to the first tab 221 and welded to the wall portion 211, meaning that the first tab 221 and the wall portion 211 are electrically connected through the current collector 24. The wall portion 211 belongs to the outer casing 21, thus the outer casing 21 forms an output pole with the same polarity as the first tab 221.

[0215] The current collector 24 is welded to the wall portion 211 to form a weld mark Q. Part of the weld mark Q is located on the wall body 2111, another part is located on the current collector 24, and yet another part may be located on the first protective layer 2112. If the wall portion 211 also includes a second protective layer 2113, then a part of the weld mark is also located on the first protective layer 2112.

[0216] The current collector 24 and the first electrode lug 221 can be connected by welding, conductive adhesive, etc. The current collector 24 and the wall portion 211 can be connected by laser welding, ultrasonic welding, etc.

[0217] In embodiments where the end cap 213 is a wall portion 211, the first electrode lug 221 can be welded to the end cap 213 via a current collector 24. In embodiments where the side wall 2122 of the housing 212 is a wall portion 211, the first electrode lug 221 can be welded to the side wall 2122 via a current collector 24. In embodiments where the bottom wall 2123 of the housing 212 is a wall portion 211, the first electrode lug 221 can be welded to the bottom wall 2123 via a current collector 24.

[0218] Figure 7 The diagram shows that the end cap 213 is a wall portion 211. The end cap 213 includes a wall body 2111 and a first protective layer 2112. The first electrode tab 221 is electrically connected to the end cap 213 through a current collector 24. The current collector 24 is welded to the end cap 213 to form a solder mark Q. A portion of the solder mark Q is located on the wall body 2111 of the end cap 213, a portion of the solder mark Q is located on the current collector 24, and another portion of the solder mark Q is located on the first protective layer 2112.

[0219] like Figure 11 As shown, the end cap 213 is a wall portion 211. The end cap 213 includes a wall body 2111, a first protective layer 2112, and a second protective layer 2113. The first electrode tab 221 is electrically connected to the end cap 213 through a current collector 24. The current collector 24 is welded to the end cap 213 to form a solder mark. A portion of the solder mark is located on the wall body 2111 of the end cap 213, a portion of the solder mark Q is located on the first protective layer 2112, and another portion of the solder mark Q is located on the second protective layer 2113.

[0220] The current collector 24 is connected to the first tab 221 and welded to the wall portion 211. That is, the outer casing 21 and the first tab 221 are electrically connected through the current collector 24. The outer casing 21 forms one output terminal of the battery cell 20. Connecting the first tab 221 and the wall portion 211 through the current collector 24 improves current carrying capacity and facilitates the electrical connection of the second tab 222 to the outer casing 21. A portion of the weld mark Q formed by the welding connection between the current collector 24 and the wall portion 211 is located on the wall body 2111. The wall body 2111 is made of carbon steel, which has good conductivity, helping to reduce the resistance of the battery cell 20, reduce losses, and increase the charging rate. Stainless steel has good rust resistance. Therefore, when the outer casing 21 serves as one output terminal of the battery cell 20, the wall body 2111 is made of carbon steel, and the first protective layer 2112 is made of stainless steel, giving the outer casing 21 of the battery cell 20 both good conductivity and good reliability.

[0221] like Figure 7 , Figure 11 As shown, in some embodiments, the housing 21 includes a housing 212 and an end cap 213. The housing 212 has an opening 2121, and the end cap 213 covers the opening 2121. The end cap 213 is a wall portion 211. The end cap 213 is welded to the current collector 24 and forms a solder mark Q.

[0222] like Figure 7 As shown, the end cap 213 includes a wall body 2111 and a first protective layer 2112. The first electrode 221 is electrically connected to the end cap 213 through a current collector 24. The current collector 24 is welded to the end cap 213 to form a solder mark. A part of the solder mark is located on the wall body 2111 of the end cap 213, a part of the solder mark Q is located on the current collector 24, and another part of the solder mark Q is located on the first protective layer 2112.

[0223] like Figure 11 As shown, the end cap 213 includes a wall body 2111, a first protective layer 2112, and a second protective layer 2113. The first electrode 221 is electrically connected to the end cap 213 through a current collector 24. The current collector 24 is welded to the end cap 213 to form a solder mark Q. A portion of the solder mark Q is located on the wall body 2111 of the end cap 213, a portion of the solder mark Q is located on the current collector 24, a portion of the solder mark Q is located on the first protective layer 2112, and another portion of the solder mark Q is located on the second protective layer 2113.

[0224] The end cap 213 is a wall portion 211. The end cap 213 is welded to the current collector 24 and forms a weld mark, which facilitates the assembly of the battery cell 20.

[0225] like Figure 3 , Figure 4 , Figure 6 , Figure 8 , Figure 10 As shown, the battery cell 20 also includes an electrode terminal 23, which is disposed on the housing 212 and is insulated from the housing 212; the electrode assembly 22 includes a second tab 222, which has opposite polarities to the first tab 221 and the second tab 222; the second tab 222 is electrically connected to the electrode terminal 23.

[0226] Electrode terminal 23 is insulated from housing 21 by insulating component 25. Figure 2 The diagram shows that electrode terminal 23 is insulated from the bottom wall 2123 of housing 212 by insulating member 25.

[0227] Electrode terminals 23 and housing 21 respectively form two output terminals of opposite polarity for the battery cell 20, facilitating charging and discharging. Electrode terminals 23 and second tabs 222 can be directly connected or indirectly connected via current collector 24. For example, the second tab 222 and electrode terminals 23 are indirectly connected via current collector 24. The current collector 24 and second tab 222 can be connected by welding, conductive adhesive, etc. The current collector 24 and terminal post can also be connected by welding, conductive adhesive, etc.

[0228] When electrode terminal 23 is electrically connected to the second tab 222 of electrode assembly 22, the housing 21 and electrode terminal 23 respectively form two output poles with opposite polarities of battery cell 20. The electrode terminal 23 is disposed in the housing 212, which facilitates the connection of the first tab 221 and the second tab 222 to the housing 212 and the electrode terminal 23 respectively, reducing the risk of interference.

[0229] In some embodiments, at least a portion of the wall of the housing 212 is a wall portion 211, the housing 212 includes a side wall 2122 and a bottom wall 2123, the side wall 2122 is disposed around the electrode assembly 22, the bottom wall 2123 is disposed opposite to the end cap 213, and the electrode terminal 23 is disposed on the bottom wall 2123.

[0230] In this embodiment, the first electrode 221 is disposed facing the end cap 213, and the second electrode 222 is disposed facing the bottom wall 2123.

[0231] The bottom wall 2123 and the end cap 213 are arranged opposite each other, and the electrode terminal 23 is arranged on the bottom wall 2123. The connection position of the first electrode tab 221 and the end cap 213 and the connection position of the second electrode tab 222 and the electrode terminal 23 are respectively located on opposite sides of the electrode assembly 22, which facilitates the welding connection of the first electrode tab 221 and the end cap 213, and facilitates the connection of the second electrode tab 222 and the electrode terminal 23.

[0232] In some embodiments, the end cap 213 is a wall portion 211, and the end cap 213 is welded to the housing 212.

[0233] The end cap 213 and the housing 212 are welded to form a welded portion, so that the end cap 213 covers the opening 2121 of the housing 212. The welded portion is arranged around the opening 2121. The end cap 213 and the housing 212 can be connected by laser welding, ultrasonic welding, etc.

[0234] The end cap 213 is welded to the housing 212, which makes the connection stability of the end cap 213 and the housing 212 higher and helps to improve the sealing performance of the end cap 213 and the housing 212, thereby improving the reliability of the battery cell 20.

[0235] In some embodiments, the wall thickness of the wall body 2111 is H, where 0.1 mm ≤ H ≤ 0.8 mm.

[0236] The wall thickness of the end cap 213 and the wall thickness of the shell 212 can be the same or different.

[0237] For example, H can be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, etc.

[0238] With H≥0.1mm, the wall thickness of the wall body 2111 is relatively large, giving the outer shell 21 better mechanical properties. With H≤0.8mm, the space occupied by the outer shell 21 can be reduced, and the volumetric energy density of the battery cell 20 can be increased. Therefore, 0.1mm≤H≤0.8mm gives the outer shell 21 better mechanical properties and the battery cell 20 better energy density.

[0239] This application provides a battery device 100, which includes the battery cell 20 provided in any of the above embodiments.

[0240] The battery cell 20 provided in any of the above embodiments has high reliability, and the battery device 100 including the battery cell 20 also has good reliability.

[0241] This application provides an electrical device, which includes a single unit or a battery device 100 provided in any of the above embodiments.

[0242] The battery cell 20 and the battery device 100 provided in any of the above embodiments have high reliability and can improve the power supply reliability of the power-consuming device powered by the battery cell 20 or the battery device 100.

[0243] This application provides a battery cell 20, which includes an electrode assembly 22 and a housing 21. The housing 21 includes a wall portion 211, which includes a wall body 2111 and a first protective layer 2112. The wall body 2111 is made of carbon steel, and the first protective layer 2112 is made of stainless steel. The first protective layer 2112 is thermally bonded to the outside of the wall body 2111. The housing 21 includes a shell 212 and an end cap 213. The shell 212 has an opening 2121, and the end cap 213 covers the opening 2121. All walls of the shell 212 and the end cap 213 are walls 211.

[0244] This application provides a battery cell 20, which includes an electrode assembly 22 and a housing 21. The housing 21 includes a wall portion 211, which includes a wall body 2111, a first protective layer 2112, and a second protective layer 2113. The wall body 2111 is made of carbon steel, while the first protective layer 2112 and the second protective layer 2113 are both made of stainless steel. The first protective layer 2112 is thermally bonded to the outer side of the wall body 2111, and the second protective layer 2113 is thermally bonded to the inner side of the wall body 2111. The housing 21 includes a shell 212 and an end cap 213. The shell 212 has an opening 2121, and the end cap 213 covers the opening 2121. All walls of the shell 212 and the end cap 213 are walls 211.

[0245] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0246] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit this application. For those skilled in the art, this application can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A battery cell, characterized in that, include: Electrode assembly; The housing contains the electrode assembly. The housing includes a wall portion, which includes a wall body and a first protective layer. The first protective layer is disposed on the outside of the wall body and covers at least a portion of the outer surface of the wall body. The wall thickness of the wall body is greater than the thickness of the first protective layer. The wall body is made of carbon steel, and the first protective layer is made of stainless steel. The stainless steel includes nickel and chromium, with nickel accounting for 2% to 20% by weight and chromium accounting for 10% to 26% by weight. The wall thickness of the wall body is H, and the thickness of the first protective layer is M. The units of H and M are mm, and 0.02≤M / (H+M)≤0.

4.

2. The battery cell as described in claim 1, characterized in that, 0.4mm≤H+M≤3mm.

3. The battery cell as described in claim 1, characterized in that, 0.05mm≤M≤0.4mm.

4. The battery cell as described in claim 3, characterized in that, 0.1mm≤M≤0.2mm.

5. The battery cell according to any one of claims 1-4, characterized in that, The wall portion further includes a second protective layer, which is disposed on the inner side of the wall body and covers at least a portion of the inner surface of the wall body. The material of the second protective layer includes stainless steel.

6. The battery cell as described in claim 5, characterized in that, The wall thickness of the wall body is greater than the thickness of the second protective layer.

7. The battery cell as described in claim 5, characterized in that, The thickness of the second protective layer is N, where N is in mm, and 0.04 ≤ (M+N) / (H+M+N) ≤ 0.

5.

8. The battery cell as described in claim 7, characterized in that, 0.4mm≤H+M+N≤3mm.

9. The battery cell as described in claim 7, characterized in that, 0.05mm≤N≤0.4mm.

10. The battery cell as described in claim 9, characterized in that, 0.1mm≤N≤0.2mm.

11. The battery cell according to any one of claims 1-4, characterized in that, The nickel content is 8% to 10.5% by weight, and the chromium content is 17.5% to 19.5% by weight.

12. The battery cell according to any one of claims 1-4, characterized in that, The housing includes a shell and an end cap, the shell having an opening, the end cap sealing the opening, the end cap being the wall portion and / or at least a portion of the wall of the shell being the wall portion.

13. The battery cell according to any one of claims 1-4, characterized in that, The electrode assembly includes a first tab, and the battery cell further includes a current collector. The current collector is connected to the first tab and welded to the wall to form a solder mark. A portion of the solder mark is located on the wall body.

14. The battery cell as described in claim 13, characterized in that, The outer casing includes a housing and an end cap. The housing has an opening, and the end cap covers the opening. The end cap is the wall portion, and the end cap is welded to the current collecting member to form the weld mark.

15. The battery cell as described in claim 14, characterized in that, The battery cell further includes an electrode terminal, which is disposed on the housing and insulated from the housing; the electrode assembly includes a second tab, the first tab and the second tab having opposite polarities, and the second tab being electrically connected to the electrode terminal.

16. The battery cell as described in claim 15, characterized in that, At least a portion of the wall of the housing is the wall portion, the housing includes a side wall and a bottom wall, the side wall is disposed around the electrode assembly, the bottom wall is disposed opposite to the end cap, and the electrode terminal is disposed on the bottom wall.

17. The battery cell as described in claim 14, characterized in that, The end cap is welded to the housing.

18. A battery device, characterized in that, Includes the battery cell as described in any one of claims 1-17.

19. An electrical appliance, characterized in that, Includes a battery cell as described in any one of claims 1-17 or a battery device as described in claim 18.

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