Battery monomer, battery and electric equipment

Abstract

A battery cell (20), a battery (100), and an electric device. The battery monomer (20) comprises a shell (21) and an electrode assembly (22), the shell (21) comprises a shell body (211) and end covers (212), at least one end of the shell body (211) along a first direction is provided with an opening, the end covers (212) are in one-to-one correspondence with the openings, and the end covers (212) seal the openings. The electrode assembly (22) is housed within the housing (21). The shell (211) is made of a steel material or a titanium alloy material, the shell (211) comprises a side wall (2111) arranged around the electrode assembly (22), the side wall (2111) is provided with a first inner surface (2111b) and a first outer surface (2111a), in the first direction, the area of a region defined by the projection of the first inner surface (2111b) is S1, and in the second direction, the area of a region defined by the projection of the first outer surface (2111a) is S2. The area of a region defined by the projection of the first outer surface (2111a) is S2, and S1 / S2 is greater than or equal to 96.42% and less than or equal to 99.75%. The wall thickness of the shell (211) made of a steel material or a titanium alloy material can be thinner. And when S1 / S2 is greater than or equal to 96.42% and less than or equal to 99.75%, the energy density and the reliability of the battery monomer (20) can be considered.

Description

Battery cells, batteries and electrical equipment Technical Field

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

[0002] Batteries are widely used in the new energy field, such as in electric vehicles and new energy vehicles, which have become a new trend in the automotive industry. The development of battery technology must consider multiple design factors simultaneously, such as battery life, discharge capacity, and charge / discharge rate. Additionally, battery energy density also needs to be considered. However, the energy density of current batteries is relatively low.

[0003] Summary of the Invention

[0004] The purpose of this application is to provide a battery cell, a battery, and an electrical device, which aims to improve the problem of low energy density in batteries in related technologies.

[0005] In a first aspect, embodiments of this application provide a battery cell, the battery cell including a casing and an electrode assembly, the casing including a housing and an end cap, the housing having an opening at at least one end along a first direction, the end cap corresponding to each opening and closing the opening; the electrode assembly being housed within the casing; wherein the housing is made of steel or titanium alloy, the housing including a sidewall surrounding the electrode assembly, the sidewall having a first inner surface and a first outer surface, along the first direction, the area defined by the projection of the first inner surface is S1, the area defined by the projection of the first outer surface is S2, satisfying: 96.42% ≤ S1 / S2 ≤ 99.75%.

[0006] In the above technical solutions, steel and titanium alloy materials have higher strength. With the same structural strength, the wall thickness of the casing made of steel or titanium alloy can be thinner. When S1 / S2 ≥ 96.42%, the thinner sidewall thickness results in a larger internal space for the casing, allowing for larger electrode components and more electrolyte. Under the same chemical material system, the volumetric energy density of the battery cell can be improved. When S1 / S2 ≤ 99.75%, the sidewall thickness is not too thin, ensuring sufficient structural strength for the casing, effectively protecting the electrode components and improving the reliability of the battery cell. Therefore, when 96.42% ≤ S1 / S2 ≤ 99.75%, both energy density and reliability of the battery cell can be balanced.

[0007] As an optional technical solution in this application embodiment, along the second direction, the sidewall includes two first wall portions disposed opposite to each other, at least one of the first wall portions being the wall portion with the largest outer surface area in the outer shell, and the second direction being perpendicular to the first direction; along the second direction, the first wall portion has a second outer surface and a second inner surface, the distance between the second inner surfaces of the two first wall portions is L1, and the distance between the second outer surfaces of the two first wall portions is L2, satisfying: 97.7% ≤ L1 / L2 ≤ 99.9%.

[0008] In the above technical solution, when L1 / L2 ≥ 97.7%, the ratio of the distance between the second inner surfaces of the two first walls to the distance between the second outer surfaces of the two first walls is relatively large, indicating that the thickness of the first walls is relatively small. This is beneficial for increasing the internal space of the casing, allowing the casing to accommodate larger electrode components and more electrolyte, thereby improving the energy density of the battery cell. When L1 / L2 ≤ 99.9%, the ratio of the distance between the second inner surfaces of the two first walls to the distance between the second outer surfaces of the two first walls is not too large, and the thickness of the first walls is not too small, ensuring that the first walls have sufficient structural strength, which is beneficial for protecting the electrode components and improving the reliability of the battery cell. Therefore, when 97.7% ≤ L1 / L2 ≤ 99.9%, both the energy density and reliability of the battery cell can be balanced.

[0009] As an optional technical solution in this application embodiment, the thickness of the first wall is H1, which satisfies: 0.05mm≤H1≤0.3mm.

[0010] In the above technical solution, when H1 ≤ 0.3 mm, the thickness of the first wall is relatively small, which is beneficial for increasing the internal space of the casing, allowing the casing to accommodate larger electrode components and more electrolyte, thereby improving the energy density of the battery cell. When H1 ≥ 0.05 mm, the thickness of the first wall is not too small, ensuring sufficient structural strength to protect the electrode components and improve the reliability of the battery cell. Therefore, when 0.05 mm ≤ H1 ≤ 0.3 mm, both the energy density and reliability of the battery cell can be balanced.

[0011] As an optional technical solution in this application embodiment, the second direction is the width direction of the outer shell, 10mm≤L2≤100mm.

[0012] In the above technical solution, when 10mm≤L2≤100mm, the width of the shell is moderate, easy to manufacture, and has strong compatibility.

[0013] As an optional technical solution in this application embodiment, the sidewall includes two first wall portions disposed opposite to each other along a second direction and two second wall portions disposed opposite to each other along a third direction. The first wall portions are the wall portions with the largest outer surface area in the outer shell. The second wall portions are adjacent to the first wall portions. The first direction, the second direction, and the third direction are perpendicular to each other. Along the third direction, the second wall portions have a third outer surface and a third inner surface. The distance between the third inner surfaces of the two second wall portions is L3, and the distance between the third outer surfaces of the two second wall portions is L4, satisfying: 99% ≤ L3 / L4 ≤ 99.95%.

[0014] In the above technical solution, when L3 / L4 ≥ 99%, the ratio of the distance between the third inner surfaces of the two second walls to the distance between the third outer surfaces of the two second walls is relatively large, indicating that the thickness of the second walls is relatively small. This is beneficial for increasing the internal space of the casing, allowing the casing to accommodate larger electrode components and more electrolyte, thereby improving the energy density of the battery cell. When L3 / L4 ≤ 99.95%, the ratio of the distance between the third inner surfaces of the two second walls to the distance between the third outer surfaces of the two second walls is not too large, and the thickness of the second walls is not too small, ensuring that the second walls have sufficient structural strength, which is beneficial for protecting the electrode components and improving the reliability of the battery cell. Therefore, when 99% ≤ L3 / L4 ≤ 99.95%, both the energy density and reliability of the battery cell can be balanced.

[0015] As an optional technical solution in this application embodiment, the thickness of the second wall is H2, which satisfies: 0.05mm≤H2≤0.4mm.

[0016] In the above technical solution, when H2 ≤ 0.4 mm, the thickness of the second wall is relatively small, which is beneficial for increasing the internal space of the casing, allowing for larger electrode components and more electrolyte, thereby improving the energy density of the battery cell. When H2 ≥ 0.05 mm, the thickness of the second wall is not too small, ensuring sufficient structural strength to protect the electrode components and improve the reliability of the battery cell. Therefore, when 0.05 mm ≤ H2 ≤ 0.4 mm, both the energy density and reliability of the battery cell can be balanced.

[0017] As an optional technical solution in this application embodiment, the third direction is the length direction of the shell, 100mm≤L4≤400mm.

[0018] In the above technical solution, when 100mm≤L4≤400mm, the length of the shell is moderate, easy to manufacture, and highly compatible.

[0019] As an optional technical solution in this application embodiment, the housing includes a bottom wall, and the side wall surrounds the bottom wall. One end of the side wall is connected to the bottom wall, and the other end of the side wall forms the opening. Along the first direction, the distance between the inner surface of the end cap and the inner surface of the bottom wall is L5, and the distance between the outer surface of the end cap and the outer surface of the bottom wall is L6, satisfying: 98% ≤ L5 / L6 ≤ 99.7%.

[0020] In the above technical solution, when L5 / L6 ≥ 98%, the ratio of the distance between the inner surface of the end cap and the inner surface of the bottom wall to the distance between the outer surface of the end cap and the outer surface of the bottom wall is relatively large. This indicates that the thickness of the end cap and the bottom wall is relatively small, which is beneficial to increasing the internal space of the casing. This allows the casing to accommodate larger electrode components and more electrolyte, thereby improving the energy density of the battery cell. When L5 / L6 ≤ 99.7%, the ratio of the distance between the inner surface of the end cap and the inner surface of the bottom wall to the distance between the outer surface of the end cap and the outer surface of the bottom wall is not too large, and the thickness of the end cap and the bottom wall is not too small. This ensures that the thickness of the end cap and the bottom wall has sufficient structural strength, which is beneficial to protecting the electrode components and improving the reliability of the battery cell. Therefore, when 98% ≤ L5 / L6 ≤ 99.7%, both the energy density and reliability of the battery cell can be balanced.

[0021] As an optional technical solution in this application embodiment, the thickness of the end cap is H3, which satisfies: 0.2mm≤H3≤1.2mm.

[0022] In the above technical solution, when H3 ≤ 1.2 mm, the end cap thickness is relatively small, which helps to increase the internal space of the casing, allowing for larger electrode components and more electrolyte, thereby improving the energy density of the battery cell. When H3 ≥ 0.2 mm, the end cap thickness is not too small, ensuring sufficient structural strength to protect the electrode components and improve the reliability of the battery cell. Therefore, when 0.2 mm ≤ H3 ≤ 1.2 mm, both the energy density and reliability of the battery cell can be balanced.

[0023] As an optional technical solution in this application embodiment, the thickness of the bottom wall is H4, which satisfies: 0.2mm≤H4≤1mm.

[0024] In the above technical solutions, when H4 ≤ 1 mm, the bottom wall thickness is relatively small, which helps to increase the internal space of the casing, allowing for larger electrode components and more electrolyte, thereby improving the energy density of the battery cell. When H4 ≥ 0.2 mm, the bottom wall thickness is not too small, ensuring sufficient structural strength to protect the electrode components and improve the reliability of the battery cell. When 0.2 mm ≤ H4 ≤ 1 mm, both the energy density and reliability of the battery cell can be balanced.

[0025] As an optional technical solution in this application embodiment, the first direction is the height direction of the outer shell, 70mm≤L6≤400mm.

[0026] In the above technical solution, when 70mm≤L6≤400mm, the length of the shell is moderate, easy to manufacture, and has strong compatibility.

[0027] As an optional technical solution in this application embodiment, the outer shell is cylindrical, the inner diameter of the sidewall is D1, and the outer diameter of the sidewall is D2, satisfying: 97.7% ≤ D1 / D2 ≤ 99.9%.

[0028] In the above technical solutions, when D1 / D2 ≥ 97.7%, the ratio of the inner diameter to the outer diameter of the sidewall is relatively large, indicating a smaller sidewall thickness. This is beneficial for increasing the internal space of the casing, allowing for larger electrode components and more electrolyte, thereby improving the energy density of the battery cell. When D1 / D2 ≤ 99.9%, the ratio of the inner diameter to the outer diameter of the sidewall is not too large, and the sidewall thickness is not too small, ensuring sufficient structural strength for the sidewall, which helps protect the electrode components and improves the reliability of the battery cell. When 97.7% ≤ D1 / D2 ≤ 99.9%, both the energy density and reliability of the battery cell can be balanced.

[0029] As an optional technical solution in this application embodiment, 10mm≤D2≤400mm.

[0030] In the above technical solution, when 10mm≤D2≤400mm, the outer diameter of the sidewall is moderate, easy to manufacture, and has strong compatibility.

[0031] As an optional technical solution in this application embodiment, the outer shell is rectangular, the electrode assembly includes a tab and a main body, the tab protrudes from the main body; the length of the main body is A, the width of the main body is B, the height of the main body is C, and the volume of the outer shell is V, satisfying: 83.2% ≤ A·B·C / V ≤ 94.5%.

[0032] In the above technical solutions, when A·B·C / V ≥ 83.2%, the volume of the electrode assembly accounts for a relatively large proportion of the casing volume, resulting in a high energy density for the battery cell. When A·B·C / V ≤ 94.5%, the volume of the electrode assembly does not account for an excessively large proportion of the casing volume, allowing sufficient space within the casing to accommodate the electrolyte and other electrical connection components. Therefore, when 83.2% ≤ A·B·C / V ≤ 94.5%, it is possible to conveniently accommodate the electrolyte and other electrical connection components while also enabling the battery cell to achieve a high energy density.

[0033] As an optional technical solution in this application embodiment, the outer shell is cylindrical, the electrode assembly includes a tab and a main body, the tab protruding from the main body; the radius of the main body is R, the height of the main body along the first direction is H, and the volume of the outer shell is V, satisfying: 83.2% ≤ H·π·R 2 / V≤94.5%.

[0034] In the above technical solution, when H·π·R 2 When / V≥83.2%, the volume of the electrode assembly accounts for a large proportion of the casing volume, and the energy density of the battery cell is high. When H·π·R 2 When / V≤94.5%, the volume of the electrode assembly will not be too large a proportion of the housing volume, allowing sufficient space within the housing to accommodate the electrolyte and other electrical connection components. Therefore, when 83.2%≤H·π·R 2 When / V≤94.5%, it can not only facilitate the accommodation of electrolyte and other electrical connection components, but also enable the battery cell to have a high energy density.

[0035] As an optional technical solution in this application embodiment, the steel material is stainless steel.

[0036] In the above technical solutions, stainless steel has advantages such as corrosion resistance, high temperature resistance, and good processing performance. Shells made of stainless steel have high strength, allowing for thinner walls while maintaining the same structural strength. Furthermore, stainless steel shells are not easily corroded, which helps extend the lifespan of individual battery cells.

[0037] As an optional technical solution in this application embodiment, the end cap is made of steel or titanium alloy.

[0038] In the above technical solutions, steel and titanium alloy materials have higher strength. Under the condition that the structural strength of the end cap is the same, the thickness of the end cap made of steel or titanium alloy can be thinner, which is conducive to increasing the internal space of the shell. This allows the shell to accommodate larger electrode components and more electrolyte. Under the same chemical material system, the volumetric energy density of the battery cell can be improved.

[0039] Secondly, embodiments of this application also provide a battery, the battery comprising the aforementioned battery cell.

[0040] Thirdly, embodiments of this application also provide an electrical device, the electrical device including the aforementioned battery cell, the battery cell being used to provide electrical energy to the electrical device. Attached Figure Description

[0041] 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.

[0042] Figure 1 is a schematic diagram of the vehicle structure provided in some embodiments of this application;

[0043] Figure 2 is an exploded view of a battery provided in some embodiments of this application;

[0044] Figure 3 is an exploded view of a single battery cell provided in some embodiments of this application;

[0045] Figure 4 is a schematic diagram of the structure of a battery cell provided in some embodiments of this application;

[0046] Figure 5 is a top view of the housing provided in some embodiments of this application;

[0047] Figure 6 is a front view schematic diagram of a battery cell provided in some embodiments of this application;

[0048] Figure 7 is a cross-sectional view of position AA in Figure 6;

[0049] Figure 8 is a top view of a single battery cell provided in some embodiments of this application;

[0050] Figure 9 is a cross-sectional view of the BB position in Figure 8;

[0051] Figure 10 is a schematic diagram of the structure of a battery cell provided in some other embodiments of this application;

[0052] Figure 11 is an exploded view of a battery cell provided in some other embodiments of this application;

[0053] Figure 12 is a top view of the housing provided in some other embodiments of this application;

[0054] Figure 13 is a top view of a battery cell provided in some other embodiments of this application;

[0055] Figure 14 is a cross-sectional view of the CC position in Figure 13.

[0056] Icons: 10-Box; 11-First part; 12-Second part; 20-Battery cell; 21-Outer casing; 211-Housing shell; 2111-Side wall; 21111-First wall portion; 21111a-Second outer surface; 2111b-First inner surface; 21112-Second wall portion; 21112a-Third outer surface; 21112b-Third inner surface; 2111a-First outer surface; 21111b-Second inner surface; 2112-Bottom wall; 212-End cap; 22-Electrode assembly; 221-Main body; 222-Electrode tab; 24-Electrode terminal; 100-Battery; 200-Controller; 300-Motor; 1000-Vehicle. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0058] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0059] 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.

[0060] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0061] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0062] 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.

[0063] In this application, "multiple" means two or more (including two).

[0064] 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.

[0065] The battery cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and the embodiments of this application are not limited to this.

[0066] 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, helps prevent short circuits to some extent while allowing active ions to pass through.

[0067] 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.

[0068] 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.

[0069] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, it can be aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0070] 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 battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxide may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds.

[0071] 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.

[0072] In some embodiments, the negative electrode can be a negative electrode sheet, and the negative electrode sheet can include a negative current collector.

[0073] 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 silver-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrode, nickel, or titanium, etc. Foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0074] 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.

[0075] 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.

[0076] 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 battery negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0077] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0078] In some embodiments, the electrode assembly further includes an isolator disposed between the positive and negative electrodes.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

[0100] In some embodiments, the housing can be a sealed structure or a non-sealed structure. As an example, when the housing is a sealed structure, it can protect the electrode assembly and prevent, to some extent, electrolyte leakage. When the housing is a non-sealed structure, it can still protect the electrode assembly, and a sealing bag may be included between the housing and the electrode assembly to encapsulate the electrode assembly and electrolyte. Specifically, the sealing bag can be a bag-shaped insulating component or an aluminum-plastic film.

[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, but are not limited to, square battery cells, blade-shaped battery cells, and multi-prismatic batteries, such as hexagonal prismatic batteries.

[0102] The battery mentioned in the embodiments of this application refers to a single physical module comprising one or more battery cells to provide higher voltage and capacity.

[0103] In some embodiments, the battery can be a battery module, and when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0104] In some embodiments, the battery can be a battery pack, which includes a housing and individual battery cells, with the individual battery cells or battery modules housed within the housing.

[0105] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0106] In some embodiments, the battery can be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0107] Currently, judging from market trends, battery applications are becoming increasingly widespread. Batteries are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but also extensively in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. With the continuous expansion of battery applications, market demand is also constantly increasing.

[0108] The development of battery technology must consider multiple design factors simultaneously, such as battery life, discharge capacity, and charge / discharge rate. Additionally, battery energy density also needs to be considered. However, current batteries have relatively low energy density.

[0109] In existing technologies, the casing of a battery cell is generally made of aluminum. Aluminum has relatively low strength, necessitating a thicker casing to achieve sufficient strength. This thicker casing results in less internal space, leading to lower energy density in the battery cell. Conversely, directly reducing the casing thickness would result in insufficient strength, leading to poor reliability of the battery cell.

[0110] Therefore, this application provides a battery cell, which includes a casing and an electrode assembly. The casing includes a housing and an end cap. The housing has an opening at at least one end along a first direction, and the end cap corresponds to each opening, closing the opening. The electrode assembly is housed within the casing. The housing is made of steel or titanium alloy. The housing includes a sidewall surrounding the electrode assembly, and the sidewall has a first inner surface and a first outer surface. Along the first direction, the area defined by the projection of the first inner surface is S1, and the area defined by the projection of the first outer surface is S2, satisfying: 96.42% ≤ S1 / S2 ≤ 99.75%.

[0111] Steel and titanium alloys offer higher strength, allowing for thinner casings with the same structural strength. When S1 / S2 ≥ 96.42%, thinner sidewalls result in a larger internal space, accommodating larger electrode components and more electrolyte. This improves the volumetric energy density of the battery cell within the same chemical system. When S1 / S2 ≤ 99.75%, the sidewalls are not excessively thin, ensuring sufficient structural strength to effectively protect the electrode components and enhance battery cell reliability. Therefore, a balance between energy density and reliability can be achieved when 96.42% ≤ S1 / S2 ≤ 99.75%.

[0112] The battery cells disclosed in this application can be used, but are not limited to, in electrical equipment such as vehicles, ships, or aircraft. A power system for such electrical equipment can be constructed using battery cells and batteries disclosed in this application, which helps to improve the energy density of the battery cells and extend the range of the electrical equipment.

[0113] Electrical equipment can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc.; electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc.; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, which may include, but are not limited to, electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc.

[0114] For ease of explanation, the following embodiments will use a vehicle 1000 as an example of electrical equipment.

[0115] Please refer to Figure 1, which is a structural schematic diagram of a vehicle 1000 provided in some embodiments of this application. The vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery 100 is disposed inside the vehicle 1000, and the battery 100 can be located at the bottom, front, or rear of the vehicle 1000. The battery 100 can be used to power the vehicle 1000; for example, the battery 100 can serve as the operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to supply power to the motor 300, for example, to meet the power needs of the vehicle 1000 during startup, navigation, and driving.

[0116] In some embodiments of this application, the battery 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.

[0117] Please refer to Figure 2, which is an exploded view of a battery 100 provided in some embodiments of this application. The battery 100 includes a housing 10 and battery cells 20, with the battery cells 20 housed within the housing 10.

[0118] The housing 10 provides a space for accommodating the battery cell 20, and the housing 10 can adopt various structures. In some embodiments, the housing 10 may include a first part 11 and a second part 12, which overlap each other, and together define a space for accommodating the battery cell 20. The second part 12 may be a hollow structure with one end open, and the first part 11 may be a plate-like structure, with the first part 11 covering the open side of the second part 12 so that the first part 11 and the second part 12 together define the space; alternatively, the first part 11 and the second part 12 may both be hollow structures with one side open, with the open side of the first part 11 covering the open side of the second part 12.

[0119] Of course, the box 10 formed by the first part 11 and the second part 12 can be of various shapes, such as a cylinder, a cuboid, etc. For example, in Figure 2, the shape of the box 10 is a cuboid.

[0120] In battery 100, there can be multiple battery cells 20. These multiple battery cells 20 can be connected in series, in parallel, or in a mixed manner. A mixed connection means that multiple battery cells 20 are connected in both series and parallel. Multiple battery cells 20 can be directly connected in series, in parallel, or in a mixed manner, and then the whole assembly of multiple battery cells 20 is housed in the housing 10. Alternatively, battery 100 can also be composed of multiple battery cells 20 first connected in series, in parallel, or in a mixed manner to form a battery module, and then multiple battery modules are connected in series, in parallel, or in a mixed manner to form a whole, which is then housed in the housing 10.

[0121] In some embodiments, the battery 100 may also include other structures. For example, the battery 100 may also include a busbar for connecting multiple battery cells 20 to achieve electrical connection between the multiple battery cells 20.

[0122] Each battery cell 20 can be a secondary battery cell or a primary battery cell; it can also be a lithium-sulfur battery cell, a sodium-ion battery cell, or a magnesium-ion battery cell, but is not limited to these. The battery cell 20 can be cylindrical, flat, cuboid, or other shapes. For example, in Figure 2, the battery cell 20 has a cuboid structure.

[0123] Please refer to Figures 3, 4, and 5. Figure 3 is an exploded view of a battery cell 20 provided in some embodiments of this application. Figure 4 is a structural schematic diagram of a battery cell 20 provided in some embodiments of this application. Figure 5 is a top view of a housing 211 provided in some embodiments of this application. This application provides a battery cell 20, which includes a housing 21 and an electrode assembly 22. The housing 21 includes a housing 211 and an end cap 212. The housing 211 has an opening at at least one end along a first direction, and the end cap 212 corresponds to each opening, closing the opening. The electrode assembly 22 is housed within the housing 21. The housing 211 is made of steel or titanium alloy. The housing 211 includes a sidewall 2111 surrounding the electrode assembly 22, and the sidewall 2111 has a first inner surface 2111b and a first outer surface 2111a. Along the first direction, the area defined by the projection of the first inner surface 2111b is S1, and the area defined by the projection of the first outer surface 2111a is S2, satisfying: 96.42% ≤ S1 / S2 ≤ 99.75%.

[0124] Battery cell 20 refers to the smallest unit that makes up battery 100.

[0125] The outer casing 21 can also be used to contain an electrolyte, such as an electrolyte solution. The outer casing 21 can have various structural forms, such as a cylinder, cuboid, or prism. The outer casing 21 includes a housing 211 and end caps 212. In some embodiments, the housing 211 has a receiving space with an opening at one end for accommodating the electrode assembly 22. The end caps 212 are connected to the housing 211 and close the opening. In other embodiments, the housing 211 has receiving spaces with openings at both ends for accommodating the electrode assembly 22. Two end caps 212 are respectively connected to both ends of the housing 211 and close the two openings.

[0126] End cap 212 refers to a component that covers the opening of housing 211 to isolate the internal environment of battery cell 20 from the external environment. The shape of end cap 212 can be adapted to the shape of housing 211 to fit it. Optionally, end cap 212 can be made of a material with certain hardness and strength (such as aluminum alloy), so that end cap 212 is not easily deformed under pressure and impact, giving battery cell 20 higher structural strength and improved reliability. The material of end cap 212 can include, but is not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, and plastic. End cap 212 is also provided with electrode terminals 24, which are used for electrical connection with the tabs 222 of electrode assembly 22 to input or output electrical energy of battery cell 20. Electrode terminals 24 and tabs 222 can be directly connected, for example, by direct welding of electrode terminals 24 to tabs 222. The electrode terminal 24 and the tab 222 can also be indirectly connected, for example, through a current collector. The battery cell 20 also includes an insulating component disposed inside the end cap 212. This insulating component isolates the electrical connection components within the housing 211 from the end cap 212, reducing the risk of short circuits. For example, the insulating component can be made of plastic, rubber, etc.

[0127] The housing 211 is a component used to cooperate with the end cap 212 to form the internal environment of the battery cell 20. This internal environment can accommodate the electrode assembly 22, electrolyte, and other components. The housing 211 and the end cap 212 can be independent components. An opening can be provided on the housing 211, and the end cap 212 can be used to close the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 212 and the housing 211 can be integrated. Specifically, the end cap 212 and the housing 211 can form a common mating surface before other components are inserted into the housing. When it is necessary to encapsulate the interior of the housing 211, the end cap 212 closes the housing 211. The housing 211 can have various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 211 can be determined according to the specific shape and size of the electrode assembly 22. The material of the housing 211 can include, but is not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0128] When assembling the battery cell 20, the electrode assembly 22 can be placed into the housing 211 first, and the electrolyte can be filled into the housing 211. Then, the end cap 212 can be closed onto the opening of the housing 211 to complete the assembly of the battery cell 20.

[0129] The outer casing 21 can be of various shapes, such as a cylinder or a cuboid. The shape of the outer casing 21 can be determined according to the specific shape of the electrode assembly 22. For example, if the electrode assembly 22 is a cylindrical structure, then the outer casing 21 can be a cylindrical structure; if the electrode assembly 22 is a cuboid structure, then the outer casing 21 can be a cuboid structure. For example, in Figures 3 and 4, the outer casing 21 is a cuboid structure.

[0130] Electrode assembly 22 is the component in the battery cell 20 where electrochemical reactions occur. The casing 211 may contain one or more electrode assemblies 22. The electrode assembly 22 is mainly formed by winding or stacking positive and negative electrode sheets, and typically a separator is provided between the positive and negative electrode sheets. The portions of the positive and negative electrode sheets containing active material constitute the main body 221 of the electrode assembly 22, while the portions of the positive and negative electrode sheets without active material each constitute a tab 222. The positive and negative tabs may be located together at one end of the main body 221 or separately at both ends of the main body 221. During the charging and discharging process of the battery 100, the positive and negative active materials react with the electrolyte.

[0131] In Figures 3 and 4, the battery cell 20 includes two electrode terminals 24, both of which are insulated and mounted on the end cap 212. Correspondingly, the electrode assembly 22 has two tabs 222 formed at one end of the main body 221 along a first direction, and the two tabs 222 have opposite polarities, thereby enabling the input or output of the positive and negative electrodes of the electrode assembly 22. The two tabs 222 are electrically connected to the two electrode terminals 24 respectively. It should be noted that the tabs 222 of the electrode assembly 22 are formed by stacking and connecting the regions of the positive electrode sheet that are not coated with a positive active material layer, or by stacking and connecting the regions of the negative electrode sheet that are not coated with a negative active material layer. If tab 222 is used as the positive electrode of output electrode assembly 22, then tab 222 is a component formed by stacking and connecting the regions on the positive electrode sheet that are not coated with the positive electrode active material layer; if tab 222 is used as the negative electrode of output electrode assembly 22, then tab 222 is a component formed by stacking and connecting the regions on the negative electrode sheet that are not coated with the negative electrode active material layer.

[0132] Of course, the structure of the battery cell 20 is not limited to this. In other embodiments, the two electrode terminals 24 may also be disposed on the two walls of the housing 21. One electrode terminal 24 may be disposed on the end cap 212 and the other electrode terminal 24 may be disposed on the housing 211, or both electrode terminals 24 may be disposed on the housing 211.

[0133] Optionally, the electrode assembly 22 housed within the housing 21 may be one or more. For example, the electrode assembly 22 housed within the housing 21 may also be one, two, three, four, five, six, seven, or eight, etc.

[0134] The electrode terminal 24 serves to input or output electrical energy to the battery cell 20. The electrode terminal 24 is electrically connected to the tab 222 to input or output electrical energy to the battery cell 20. It should be noted that the electrode terminal 24 is insulated and mounted on the end cover 212 of the housing 21, that is, there is no electrical connection between the electrode terminal 24 and the end cover 212 of the housing 21.

[0135] Alternatively, the electrode terminal 24 can be made of various materials, such as copper, iron, aluminum, steel, or aluminum alloy.

[0136] In some embodiments, the battery cell 20 may also include two current collectors, both of which are disposed within the housing 21. Each current collector is used to connect an electrode terminal 24 and a tab 222 of the same polarity in the electrode assembly 22, so as to realize the electrical connection between the electrode terminal 24 and the electrode assembly 22, which helps to reduce the assembly difficulty between the tab 222 and the electrode terminal 24.

[0137] For example, the material of the current collector can be various, such as copper, iron, aluminum, steel or aluminum alloy.

[0138] Please refer to Figure 7. The first direction is the Z direction shown in the figure.

[0139] The steel material can be carbon steel or stainless steel. Carbon steel can be low-carbon steel, medium-carbon steel, or high-carbon steel.

[0140] Titanium alloys refer to various alloy metals made of titanium and other metals. Titanium alloys have high strength, good corrosion resistance, and high heat resistance.

[0141] The sidewall 2111 surrounds the outer side of the electrode assembly 22. When the outer shell 21 has a cuboid structure, the sidewall 2111 includes multiple wall portions connected end to end. When the outer shell 21 has a cylindrical structure, the sidewall 2111 is the peripheral wall of the outer shell 21.

[0142] The first inner surface 2111b is the surface of the sidewall 2111 facing the electrode assembly 22. When the housing 21 has a cuboid structure, the first inner surface 2111b includes the inner surfaces of a plurality of walls. When the housing 21 has a cylindrical structure, the first inner surface 2111b is the inner circumferential surface of the peripheral wall.

[0143] The first outer surface 2111a is the surface of the sidewall 2111 that faces away from the electrode assembly 22. When the housing 21 has a cuboid structure, the first outer surface 2111a includes the outer surfaces of multiple wall portions. When the housing 21 has a cylindrical structure, the first outer surface 2111a is the outer peripheral surface of the peripheral wall.

[0144] S1 is the area defined by the projection of the first inner surface 2111b along the first direction. Please refer to Figure 5, where S1 is marked with a grid. It should be noted that the grid is only for the purpose of illustrating S1 and does not represent any physical entity.

[0145] S2 is the area defined by the projection of the first outer surface 2111a along the first direction, and S2 includes S1. Referring to Figure 5, the area S3 defined by the projections of the first inner surface 2111b and the first outer surface 2111a along the first direction is indicated by cross-sectional lines. It should be noted that the cross-sectional lines are only for illustrating S3 and do not represent any physical entity. Wherein, S2 = S1 + S3.

[0146] S1 / S2 represents the ratio of the area defined by the projection of the first inner surface 2111b along the first direction to the area defined by the projection of the first outer surface 2111a along the first direction.

[0147] The ratio of the area defined by the projection of the first inner surface 2111b along the first direction to the area defined by the projection of the first outer surface 2111a along the first direction can be: S1 / S2 = 96.42%, 96.5%, 96.8%, 97%, 97.2%, 97.5%, 97.8%, 98%, 98.2%, 98.5%, 98.8%, 99%, 99.2%, 99.5%, 99.7%, 99.75%, etc.

[0148] Steel and titanium alloys have high strength, allowing for a thinner wall thickness in the casing 211 when the structural strength of the casing 211 is the same. When S1 / S2 ≥ 96.42%, the thinner wall thickness of the sidewall 2111 results in a larger internal space for the casing 211, accommodating larger electrode components 22 and more electrolyte. Under the same chemical material system, the volumetric energy density of the battery cell 20 can be improved. When S1 / S2 ≤ 99.75%, the wall thickness of the sidewall 2111 is not too thin, ensuring sufficient structural strength for the casing 211, effectively protecting the electrode components 22 and improving the reliability of the battery cell 20. Therefore, when 96.42% ≤ S1 / S2 ≤ 99.75%, both energy density and reliability of the battery cell 20 can be balanced.

[0149] Please refer to Figures 3, 4, 5, 6, and 7. Figure 6 is a front view schematic diagram of the battery cell 20 provided in some embodiments of this application. Figure 7 is a cross-sectional view at position AA in Figure 6. In some embodiments, along the second direction, the sidewall 2111 includes two opposing first wall portions 21111, at least one of which is the wall portion with the largest outer surface area in the housing 21. The second direction is perpendicular to the first direction. Along the second direction, the first wall portion 21111 has a second outer surface 21111a and a second inner surface 21111b. The distance between the first inner surfaces 2111b of the two first wall portions 21111 is L1, and the distance between the first outer surfaces 2111a of the two first wall portions 21111 is L2, satisfying: 97.7% ≤ L1 / L2 ≤ 99.9%.

[0150] The first wall portion 21111 is the wall portion with the largest outer surface area in the outer shell 21, commonly referred to as the large surface. The two first wall portions 21111 are arranged opposite each other along a second direction. Referring to Figure 7, the second direction is the X direction shown in the figure. The second direction is perpendicular to the first direction.

[0151] The second outer surface 21111a is the surface of the first wall portion 21111 that faces away from the electrode assembly 22, and the second inner surface 21111b is the surface of the first wall portion 21111 that faces the electrode assembly 22. Along the second direction, the second outer surface 21111a and the second inner surface 21111b are arranged opposite to each other.

[0152] The first outer surface 2111a includes two first wall portions 21111, and the first inner surface 2111b includes two first wall portions 21111, and the second inner surface 21111b includes two first wall portions 21111.

[0153] L1 represents the distance between the second inner surfaces 21111b of the two first wall portions 21111 along the second direction. During measurement, multiple measurements can be taken and the average value can be used as L1.

[0154] L2 represents the distance between the second outer surfaces 21111a of the two first wall portions 21111 along the second direction. During measurement, multiple measurements can be taken and the average value can be used as L1.

[0155] L1 / L2 represents the ratio of the distance between the second inner surfaces 21111b of the two first wall portions 21111 along the second direction to the distance between the second outer surfaces 21111a of the two first wall portions 21111 along the second direction.

[0156] The ratio of the distance between the second inner surfaces 21111b of the two first wall portions 21111 along the second direction to the distance between the second outer surfaces 21111a of the two first wall portions 21111 along the second direction can be: L1 / L2 = 97.7%, 97.8%, 98%, 98.2%, 98.5%, 98.8%, 99%, 99.2%, 99.5%, 99.7%, 99.75%, 99.9%, etc.

[0157] When L1 / L2 ≥ 97.7%, the ratio of the distance between the second inner surfaces 21111b of the two first wall portions 21111 to the distance between the second outer surfaces 21111a of the two first wall portions 21111 is relatively large, indicating that the thickness of the first wall portion 21111 is relatively small. This is beneficial for increasing the internal space of the housing 211, allowing the housing 211 to accommodate a larger electrode assembly 22 and more electrolyte, thereby improving the energy density of the battery cell 20. When L1 / L2 ≤ 99.9%, the ratio of the distance between the second inner surfaces 21111b of the two first wall portions 21111 to the distance between the second outer surfaces 21111a of the two first wall portions 21111 is not too large, and the thickness of the first wall portion 21111 is not too small. This ensures that the first wall portion 21111 has sufficient structural strength, which is beneficial for protecting the electrode assembly 22 and improving the reliability of the battery cell 20. Therefore, when 97.7% ≤ L1 / L2 ≤ 99.9%, the energy density and reliability of the battery cell 20 can be balanced.

[0158] Please refer to Figures 3, 4, 5, 6 and 7. In some embodiments, the thickness of the first wall portion 21111 is H1, which satisfies: 0.05mm≤H1≤0.3mm.

[0159] H1 represents the thickness of the first wall portion 21111. During measurement, multiple measurements can be taken and the average value can be used as H1.

[0160] The thickness of the first wall portion 21111 can be: H1 = 0.05mm, 0.08mm, 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, 0.22mm, 0.25mm, 0.28mm, 0.3mm, etc.

[0161] When H1 ≤ 0.3 mm, the thickness of the first wall portion 21111 is relatively small, which helps to increase the internal space of the housing 211, allowing the housing 211 to accommodate a larger electrode assembly 22 and more electrolyte, thereby improving the energy density of the battery cell 20. When H1 ≥ 0.05 mm, the thickness of the first wall portion 21111 is not too small, ensuring that the first wall portion 21111 has sufficient structural strength, which helps to protect the electrode assembly 22 and improve the reliability of the battery cell 20. Therefore, when 0.05 mm ≤ H1 ≤ 0.3 mm, both the energy density and reliability of the battery cell 20 can be balanced.

[0162] In some embodiments, a pressure relief mechanism is also provided on the housing 21. The pressure relief mechanism is a component used to open when the internal pressure or temperature of the battery cell 20 reaches the explosion pressure, thereby releasing the internal pressure of the battery cell 20. The pressure relief mechanism is a component mounted on a wall of the housing 21, and is separately provided and connected to the wall of the housing 21 (during manufacturing, a pressure relief hole is provided in a wall of the housing 21, and the pressure relief mechanism and a wall of the housing 21 are provided separately and ultimately connected together). For example, the pressure relief mechanism is an explosion-proof plate mounted on a wall of the housing 21.

[0163] Optionally, the pressure relief mechanism can be made of steel or nickel, and the wall of the housing 21 where the pressure relief mechanism is located can be made of steel. The pressure relief mechanism can be made of carbon steel or stainless steel. Carbon steel can be low-carbon steel, medium-carbon steel, or high-carbon steel. For example, the pressure relief mechanism can be made of 304 stainless steel, 305 stainless steel, 316 stainless steel, nickel, etc. By making the pressure relief mechanism made of steel or nickel, and the wall of the housing 21 where the pressure relief mechanism is located made of steel, on the one hand, the structural strength of the wall of the housing 21 where the pressure relief mechanism is located and the pressure relief mechanism itself can be effectively improved, reducing the risk of deformation due to stress, which helps reduce the risk of premature valve opening and pressure release, and improves the service life and reliability of the battery cell 20. On the other hand, steel or nickel-based pressure relief mechanisms are easier to weld to steel walls, which helps reduce the occurrence of welding cracks between the pressure relief mechanism and the wall, thereby reducing the risk of leakage from the battery cell 20 and improving its reliability.

[0164] Please refer to Figures 3, 4, 5, 6 and 7. In some embodiments, the second direction is the width direction of the outer shell 21, where 10mm ≤ L2 ≤ 100mm.

[0165] The second direction is the width direction of the outer shell 21. In this case, L2 is the width of the outer shell 21.

[0166] The width of the outer shell 21 can be: L2 = 10mm, 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, etc.

[0167] When 10mm≤L2≤100mm, the width of the outer shell 21 is moderate, easy to manufacture, and highly compatible.

[0168] Please refer to Figures 5, 6, 7, 8, and 9. Figure 8 is a top view of a battery cell 20 provided in some embodiments of this application. Figure 9 is a cross-sectional view of the BB position in Figure 8. In some embodiments, the sidewall 2111 includes two first wall portions 21111 disposed opposite each other along a second direction and two second wall portions 21112 disposed opposite each other along a third direction. The first wall portion 21111 is the wall portion with the largest outer surface area in the housing 21, and the second wall portion 21112 is adjacent to the first wall portion 21111. The first direction, the second direction, and the third direction are perpendicular to each other. Along the third direction, the second wall portion 21112 has a third outer surface 21112a and a third inner surface 21112b. The distance between the third inner surfaces 21112b of the two second wall portions 21112 is L3, and the distance between the third outer surfaces 21112a of the two second wall portions 21112 is L4, satisfying: 99% ≤ L3 / L4 ≤ 99.95%.

[0169] The second wall portion 21112 is the wall portion adjacent to the first wall portion 21111 in the side wall 2111. Generally, the second wall portion 21112 is the wall portion with the smallest outer surface area in the outer shell 21, commonly known as the small facet. The two second wall portions 21112 are arranged opposite each other along a third direction. Please refer to Figure 9, where the second direction is the Y direction shown in the figure. The first direction, the second direction, and the third direction are perpendicular to each other.

[0170] The third outer surface 21112a is the surface of the second wall portion 21112 that faces away from the electrode assembly 22, and the third inner surface 21112b is the surface of the second wall portion 21112 that faces the electrode assembly 22. Along the third direction, the third outer surface 21112a and the third inner surface 21112b are arranged opposite to each other.

[0171] The first outer surface 2111a includes a second outer surface 21111a of two first wall portions 21111 and a third outer surface 21112a of two second wall portions 21112, and the first inner surface 2111b includes a second inner surface 21111b of two first wall portions 21111 and a third inner surface 21112b of two second wall portions 21112.

[0172] L3 represents the distance between the third inner surfaces 21112b of the two second walls 21112 along a third direction. During measurement, multiple measurements can be taken and the average value can be used as L3.

[0173] L4 represents the distance between the third outer surfaces 21112a of the two second wall portions 21112 along a third direction. During measurement, multiple measurements can be taken and the average value can be used as L4.

[0174] L3 / L4 represents the ratio of the distance between the third inner surfaces 21112b of the two second wall portions 21112 along the third direction to the distance between the third outer surfaces 21112a of the two second wall portions 21112 along the third direction.

[0175] The ratio of the distance between the third inner surface 21112b of the two second wall portions 21112 along the third direction to the distance between the third outer surface 21112a of the two second wall portions 21112 along the third direction can be: L3 / L4 = 99%, 99.05%, 99.1%, 99.15%, 99.2%, 99.25%, 99.3%, 99.35%, 99.4%, 99.45%, 99.5%, 99.55%, 99.6%, 99.65%, 99.7%, 99.75%, 99.8%, 99.85%, 99.9%, 99.95%, etc.

[0176] When L3 / L4 ≥ 99%, the ratio of the distance between the third inner surfaces 21112b of the two second wall portions 21112 to the distance between the third outer surfaces 21112a of the two second wall portions 21112 is relatively large, indicating that the thickness of the second wall portion 21112 is relatively small. This is beneficial for increasing the internal space of the housing 211, allowing the housing 211 to accommodate a larger electrode assembly 22 and more electrolyte, thereby improving the energy density of the battery cell 20. When L3 / L4 ≤ 99.95%, the ratio of the distance between the third inner surfaces 21112b of the two second wall portions 21112 to the distance between the third outer surfaces 21112a of the two second wall portions 21112 is not too large, and the thickness of the second wall portion 21112 is not too small. This ensures that the second wall portion 21112 has sufficient structural strength, which is beneficial for protecting the electrode assembly 22 and improving the reliability of the battery cell 20. Therefore, when 99% ≤ L3 / L4 ≤ 99.95%, the energy density and reliability of the battery cell 20 can be balanced.

[0177] Please refer to Figures 5, 6, 7, 8 and 9. In some embodiments, the thickness of the second wall portion 21112 is H2, which satisfies: 0.05mm≤H2≤0.4mm.

[0178] H2 represents the thickness of the second wall portion 21112. During measurement, multiple measurements can be taken and the average value can be used as H2.

[0179] The thickness of the second wall portion 21112 can be: H2 = 0.05mm, 0.08mm, 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, 0.22mm, 0.25mm, 0.28mm, 0.3mm, 0.32mm, 0.35mm, 0.38mm, 0.4mm, etc.

[0180] When H2 ≤ 0.4 mm, the thickness of the second wall portion 21112 is relatively small, which helps to increase the internal space of the housing 211, allowing the housing 211 to accommodate a larger electrode assembly 22 and more electrolyte, thereby improving the energy density of the battery cell 20. When H2 ≥ 0.05 mm, the thickness of the second wall portion 21112 is not too small, ensuring that the second wall portion 21112 has sufficient structural strength, which helps to protect the electrode assembly 22 and improve the reliability of the battery cell 20. Therefore, when 0.05 mm ≤ H2 ≤ 0.4 mm, both the energy density and reliability of the battery cell 20 can be balanced.

[0181] Please refer to Figures 5, 6, 7, 8 and 9. In some embodiments, the third direction is the length direction of the outer shell 21, where 100mm ≤ L4 ≤ 400mm.

[0182] The third direction is the length direction of the outer shell 21. At this time, L4 is the length of the outer shell 21.

[0183] The length of the outer shell 21 can be: L4 = 100mm, 120mm, 150mm, 180mm, 200mm, 220mm, 250mm, 280mm, 300mm, 320mm, 350mm, 380mm, 400mm, etc.

[0184] When 100mm≤L4≤400mm, the length of the outer shell 21 is moderate, easy to manufacture, and highly compatible.

[0185] Referring to Figures 5, 6, 7, 8, and 9, in some embodiments, the housing 211 includes a bottom wall 2112, and side walls 2111 surround the bottom wall 2112. One end of the side wall 2111 is connected to the bottom wall 2112, and the other end of the side wall 2111 forms an opening. Along the first direction, the distance between the inner surface of the end cap 212 and the inner surface of the bottom wall 2112 is L5, and the distance between the outer surface of the end cap 212 and the outer surface of the bottom wall 2112 is L6, satisfying: 98% ≤ L5 / L6 ≤ 99.7%.

[0186] Along the first direction, the bottom wall 2112 and the end cap 212 are arranged opposite to each other, and the bottom wall 2112 and the end cap 212 are respectively connected to the two ends of the side wall 2111.

[0187] In some embodiments, the bottom wall 2112 and the side wall 2111 are integrally formed, that is, the shell 211 is manufactured by an integral forming process, such as stamping, casting or extrusion molding, etc. In other words, the side wall 2111 and the bottom wall 2112 of the shell 211 are an integral structure.

[0188] In other embodiments, the bottom wall 2112 and the side wall 2111 are separately provided and connected; that is, during manufacturing, the bottom wall 2112 and the side wall 2111 are provided separately and then connected together. For example, the bottom wall 2112 may be welded to the side wall 2111.

[0189] L5 represents the distance between the inner surface of the end cap 212 along the first direction and the inner surface of the bottom wall 2112. Multiple measurements can be taken and the average value can be used as L5.

[0190] L6 represents the distance between the outer surface of the end cap 212 along the first direction and the outer surface of the bottom wall 2112. Multiple measurements can be taken and the average value can be used as L6.

[0191] L5 / L6 represents the ratio of the distance between the inner surface of the end cap 212 along the first direction and the inner surface of the bottom wall 2112 to the distance between the outer surface of the end cap 212 along the first direction and the outer surface of the bottom wall 2112.

[0192] The ratio of the distance between the inner surface of the end cap 212 and the inner surface of the bottom wall 2112 along the first direction to the distance between the outer surface of the end cap 212 and the outer surface of the bottom wall 2112 along the first direction can be: L5 / L6 = 98%, 98.1%, 98.2%, 98.3%, 98.4%, 98.5%, 98.6%, 98.7%, 98.8%, 98.9%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, etc.

[0193] When L5 / L6 ≥ 98%, the ratio of the distance between the inner surface of end cap 212 and the inner surface of bottom wall 2112 to the distance between the outer surface of end cap 212 and the outer surface of bottom wall 2112 is relatively large. This indicates that the thickness of end cap 212 and bottom wall 2112 is relatively small, which is beneficial to increasing the internal space of housing 211. This allows housing 211 to accommodate larger electrode components 22 and more electrolyte, thereby improving the energy density of battery cell 20. When L5 / L6 ≤ 99.7%, the ratio of the distance between the inner surface of end cap 212 and the inner surface of bottom wall 2112 to the distance between the outer surface of end cap 212 and the outer surface of bottom wall 2112 is not too large, and the thickness of end cap 212 and bottom wall 2112 is not too small. This ensures that the thickness of end cap 212 and bottom wall 2112 has sufficient structural strength, which is beneficial to protecting electrode components 22 and improving the reliability of battery cell 20. Therefore, when 98% ≤ L5 / L6 ≤ 99.7%, the energy density and reliability of the battery cell 20 can be balanced.

[0194] Please refer to Figures 5, 6, 7, 8 and 9. In some embodiments, the thickness of the end cap 212 is H3, which satisfies: 0.2mm≤H3≤1.2mm.

[0195] H3 represents the thickness of end cap 212. During measurement, multiple measurements can be taken and the average value used as H3.

[0196] The thickness of the end cap 212 can be: H3 = 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm, 1.05mm, 1.1mm, 1.15mm, 1.2mm, etc.

[0197] When H3 ≤ 1.2 mm, the thickness of the end cap 212 is relatively small, which helps to increase the internal space of the housing 211, allowing the housing 211 to accommodate larger electrode components 22 and more electrolyte, thereby improving the energy density of the battery cell 20. When H3 ≥ 0.2 mm, the thickness of the end cap 212 is not too small, ensuring that the end cap 212 has sufficient structural strength, which helps to protect the electrode components 22 and improve the reliability of the battery cell 20. Therefore, when 0.2 mm ≤ H3 ≤ 1.2 mm, both the energy density and reliability of the battery cell 20 can be balanced.

[0198] Please refer to Figures 5, 6, 7, 8 and 9. In some embodiments, the thickness of the bottom wall 2112 is H4, which satisfies: 0.2mm≤H4≤1mm.

[0199] H4 represents the thickness of the bottom wall 2112. During measurement, multiple measurements can be taken and the average value can be used as H4.

[0200] The thickness of the bottom wall 2112 can be: H4 = 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm, etc.

[0201] When H4 ≤ 1 mm, the thickness of the bottom wall 2112 is relatively small, which helps to increase the internal space of the casing 211, allowing the casing 211 to accommodate larger electrode components 22 and more electrolyte, thereby improving the energy density of the battery cell 20. When H4 ≥ 0.2 mm, the thickness of the bottom wall 2112 is not too small, ensuring that the bottom wall 2112 has sufficient structural strength, which helps to protect the electrode components 22 and improve the reliability of the battery cell 20. When 0.2 mm ≤ H4 ≤ 1 mm, both the energy density and reliability of the battery cell 20 can be balanced.

[0202] Please refer to Figures 5, 6, 7, 8 and 9. In some embodiments, the first direction is the height direction of the outer casing 21, where 70mm ≤ L6 ≤ 400mm.

[0203] The first direction is the height direction of the outer shell 21. At this time, L6 is the height of the outer shell 21.

[0204] The height of the outer shell 21 can be: L6 = 70mm, 80mm, 90mm, 100mm, 120mm, 150mm, 180mm, 200mm, 220mm, 250mm, 280mm, 300mm, 320mm, 350mm, 380mm, 400mm, etc.

[0205] When 70mm≤L6≤400mm, the length of the outer shell 21 is moderate, easy to manufacture, and highly compatible.

[0206] Please refer to Figures 10, 11, 12, 13, and 14. Figure 10 is a structural schematic diagram of the battery cell 20 provided in some embodiments of this application. Figure 11 is an exploded view of the battery cell 20 provided in some embodiments of this application. Figure 12 is a top view of the housing 211 provided in some embodiments of this application. Figure 13 is a top view of the battery cell 20 provided in some embodiments of this application. Figure 14 is a cross-sectional view at position CC in Figure 13. In some embodiments, the housing 21 is cylindrical, with an inner diameter D1 and an outer diameter D2 of the sidewall 2111, satisfying: 97.7% ≤ D1 / D2 ≤ 99.9%.

[0207] Referring to Figure 12, when the outer shell 21 is a cylindrical structure, the first inner surface 2111b is the inner circumferential surface of the peripheral wall, and the first outer surface 2111a is the outer circumferential surface of the peripheral wall.

[0208] S1 is the area defined by the projection of the first inner surface 2111b along the first direction. Please refer to Figure 12, where S1 is marked with a grid. It should be noted that the grid is only for the purpose of illustrating S1 and does not represent any physical entity.

[0209] S2 is the area defined by the projection of the first outer surface 2111a along the first direction, and S2 includes S1. Please refer to Figure 12, where the area S3 defined by the projection of the first inner surface 2111b along the first direction and the projection of the first outer surface 2111a along the first direction is indicated by cross-sectional lines. Wherein, S2 = S1 + S3.

[0210] D1 represents the inner diameter of sidewall 2111, and D2 represents the outer diameter of sidewall 2111, which is also the outer diameter of outer shell 21. D1 / D2 represents the ratio of the inner diameter to the outer diameter of sidewall 2111.

[0211] The ratio of the inner diameter to the outer diameter of the sidewall 2111 can be: D1 / D2 = 97.7%, 97.8%, 98%, 98.2%, 98.5%, 98.8%, 99%, 99.2%, 99.5%, 99.7%, 99.75%, 99.9%, etc.

[0212] When D1 / D2 ≥ 97.7%, the ratio of the inner diameter to the outer diameter of the sidewall 2111 is relatively large, indicating a smaller thickness of the sidewall 2111. This is beneficial for increasing the internal space of the casing 211, allowing it to accommodate larger electrode components 22 and more electrolyte, thereby improving the energy density of the battery cell 20. When D1 / D2 ≤ 99.9%, the ratio of the inner diameter to the outer diameter of the sidewall 2111 is not too large, and the thickness of the sidewall 2111 is not too small, ensuring sufficient structural strength for the sidewall 2111, which helps protect the electrode components 22 and improves the reliability of the battery cell 20. When 97.7% ≤ D1 / D2 ≤ 99.9%, both the energy density and reliability of the battery cell 20 can be balanced.

[0213] Please refer to Figures 10, 11, 12, 13 and 14. In some embodiments, 10mm ≤ D2 ≤ 400mm.

[0214] D2 represents the outer diameter of the side wall 2111, which is also the outer diameter of the outer shell 21. The outer diameter of the outer shell 21 can be: D2 = 10mm, 30mm, 50mm, 80mm, 100mm, 120mm, 150mm, 180mm, 200mm, 220mm, 250mm, 280mm, 300mm, 320mm, 350mm, 380mm, 400mm, etc.

[0215] When 10mm≤D2≤400mm, the outer diameter of the sidewall 2111 is moderate, easy to manufacture, and has strong compatibility.

[0216] Please refer again to Figures 5, 6, 7, 8, and 9. In some embodiments, the outer casing 21 is rectangular. The electrode assembly 22 includes tabs 222 and a main body 221, with the tabs 222 protruding from the main body 221. The length of the main body 221 is A, the width of the main body 221 is B, the height of the main body 221 is C, and the volume of the outer casing 21 is V, satisfying: 83.2% ≤ A·B·C / V ≤ 94.5%.

[0217] When the outer shell 21 is rectangular, the main body 221 is also approximately rectangular. Here, A represents the length of the main body 221, B represents the width of the main body 221, and C represents the height of the main body 221. For ease of calculation, the volume of the main body 221 is represented by A·B·C.

[0218] V represents the volume of the outer shell 21, V = L2·L4·L6.

[0219] A·B·C / V represents the ratio of the volume of the main body 221 to the volume of the outer shell 21.

[0220] The ratio of the volume of the main body 221 to the volume of the outer shell 21 can be: A·B·C / V = 83.2%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 94.5%, etc.

[0221] When A·B·C / V ≥ 83.2%, the volume of the electrode assembly 22 accounts for a relatively large proportion of the volume of the casing 21, resulting in a high energy density for the battery cell 20. When A·B·C / V ≤ 94.5%, the volume of the electrode assembly 22 does not account for an excessively large proportion of the volume of the casing 21, allowing sufficient space within the casing 21 to accommodate the electrolyte and other electrical connection components. Therefore, when 83.2% ≤ A·B·C / V ≤ 94.5%, it is convenient to accommodate the electrolyte and other electrical connection components while also enabling the battery cell 20 to achieve a high energy density.

[0222] Referring to Figures 10, 11, 12, 13, and 14, in some embodiments, the outer casing 21 is cylindrical. The electrode assembly 22 includes tabs 222 and a main body 221, with the tabs 222 protruding from the main body 221. The radius of the main body 221 is R, the height of the main body 221 along a first direction is H, and the volume of the outer casing 21 is V, satisfying: 83.2% ≤ H·π·R 2 / V≤94.5%.

[0223] When the outer shell 21 is cylindrical, the main body 221 is also approximately cylindrical. Here, R represents the radius of the main body 221; since the main body 221 has a central hole, R can also be understood as the outer diameter of the main body 221. H represents the height of the main body 221 along the first direction, expressed as H·π·R. 2 This is used to represent the volume of the main body 221.

[0224] V represents the volume of the outer shell 21, V = H·π·(D² / 2) 2 .

[0225] H·π·R 2 / V represents the ratio of the volume of the main body 221 to the volume of the outer shell 21.

[0226] The ratio of the volume of the main body 221 to the volume of the outer shell 21 can be: H·π·R 2 / V = 83.2%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 94.5%, etc.

[0227] When H·π·R 2 When / V≥83.2%, the volume of electrode assembly 22 accounts for a large proportion of the volume of casing 21, and the energy density of battery cell 20 is high. When H·π·R 2 When / V≤94.5%, the volume of the electrode assembly 22 will not be too large a proportion of the volume of the outer casing 21, ensuring that there is sufficient space within the outer casing 21 to accommodate the electrolyte and other electrical connection components. Therefore, when 83.2%≤H·π·R 2 When / V≤94.5%, it can not only facilitate the accommodation of electrolyte and other electrical connection components, but also enable the battery cell 20 to have a high energy density.

[0228] In some embodiments, the steel material is stainless steel.

[0229] Stainless steel is a type of steel characterized by its rust resistance and corrosion resistance, with a chromium content of at least 10.5% and a carbon content of no more than 1.2%. Examples include 304 stainless steel, 305 stainless steel, and 316 stainless steel.

[0230] Stainless steel has advantages such as corrosion resistance, high temperature resistance, and good processing performance. A casing 211 made of stainless steel has high strength, allowing for a thinner wall thickness while maintaining the same structural strength. Furthermore, the stainless steel casing 211 is not easily corroded, which helps to extend the service life of the battery cell 20.

[0231] In some embodiments, the end cap 212 is made of steel or titanium alloy.

[0232] The steel material can be carbon steel or stainless steel. Carbon steel can be low-carbon steel, medium-carbon steel, or high-carbon steel. Titanium alloy refers to various alloy metals made of titanium and other metals. Titanium alloys have high strength, good corrosion resistance, and high heat resistance.

[0233] Steel and titanium alloys have high strength. With the same structural strength, the end cap 212 made of steel or titanium alloy can be thinner, which helps to increase the internal space of the outer shell 21. This allows the outer shell 21 to accommodate larger electrode components 22 and more electrolyte. Under the same chemical material system, the volumetric energy density of the battery cell 20 can be improved.

[0234] This application embodiment also provides a battery 100, which includes the battery cell 20 described above.

[0235] As shown in Figure 2, the battery 100 may also include a housing 10, in which the battery cells 20 are housed.

[0236] In some embodiments, the housing 10 may include a first portion 11 and a second portion 12, the first portion 11 and the second portion 12 overlapping each other, the first portion 11 and the second portion 12 together defining an assembly space for accommodating the battery cell 20.

[0237] Optionally, the second part 12 can be a hollow structure with one end open, and the first part 11 can be a plate-like structure. The first part 11 covers the open side of the second part 12 so that the first part 11 and the second part 12 together define the assembly space. Alternatively, the first part 11 and the second part 12 can both be hollow structures with one side open, and the open side of the first part 11 covers the open side of the second part 12.

[0238] Of course, the box 10 formed by the first part 11 and the second part 12 can be of various shapes, such as a cylinder or a cuboid. For example, in Figure 2, the box 10 is a cuboid structure.

[0239] Optionally, the battery cell 20 disposed within the housing 10 can be one or more. For example, in Figure 2, the housing 100 of the battery 100 contains multiple battery cells 20. These multiple battery cells 20 can be connected in series, parallel, or a combination thereof. A combination thereof means that some of the multiple battery cells 20 are connected in series and others in parallel. Multiple battery cells 20 can be directly connected in series, parallel, or a combination thereof, and then the entire assembly of the multiple battery cells 20 is housed within the housing 10. Alternatively, the battery 100 can also be composed of multiple battery cells 20 first connected in series, parallel, or a combination thereof to form a battery module, and then these battery modules are connected in series, parallel, or a combination thereof to form a whole, which is then housed within the housing 10.

[0240] The battery 100 may also include other structures. For example, the battery 100 may also include a busbar component that connects multiple battery cells 20 to achieve electrical connection between the multiple battery cells 20.

[0241] It should be noted that in some embodiments, the battery 100 may not have a housing 10. The battery 100 includes multiple battery cells 20, and the battery 100 composed of multiple battery cells 20 can be directly assembled to an electrical device to provide power to the electrical device through the multiple battery cells 20. That is, the housing 10 can be part of the electrical device. Taking a vehicle 1000 as an example, the housing 10 can be part of the chassis structure of the vehicle 1000. For example, a portion of the housing 10 can be at least a part of the floor of the vehicle 1000, or a portion of the housing 10 can be at least a part of the crossbeams and longitudinal beams of the vehicle 1000.

[0242] This application embodiment also provides an electrical device, which includes the aforementioned battery cell 20, and the battery cell 20 is used to provide electrical energy to the electrical device.

[0243] The electrical device can be any of the aforementioned devices or systems that utilize battery cells 20.

[0244] Please refer to Figures 3 to 14 for some embodiments of this application.

[0245] This application provides a battery cell 20, which includes a housing 21 and an electrode assembly 22. The housing 21 includes a shell 211 and an end cap 212. The shell 211 has an opening at at least one end along a first direction, and the end cap 212 corresponds to each opening and closes the opening. The electrode assembly 22 is housed within the housing 21. The shell 211 is made of steel or titanium alloy. The shell 211 includes a sidewall 2111 surrounding the electrode assembly 22, and the sidewall 2111 has a first inner surface 2111b and a first outer surface 2111a. Along the first direction, the area defined by the projection of the first inner surface 2111b is S1, and the area defined by the projection of the first outer surface 2111a is S2, satisfying: 96.42% ≤ S1 / S2 ≤ 99.75%. Steel and titanium alloys have high strength, allowing for a thinner wall thickness in the casing 211 when the structural strength of the casing 211 is the same. When S1 / S2 ≥ 96.42%, the thinner wall thickness of the sidewall 2111 results in a larger internal space for the casing 211, accommodating larger electrode components 22 and more electrolyte. Under the same chemical material system, the volumetric energy density of the battery cell 20 can be improved. When S1 / S2 ≤ 99.75%, the wall thickness of the sidewall 2111 is not too thin, ensuring sufficient structural strength for the casing 211, effectively protecting the electrode components 22 and improving the reliability of the battery cell 20. Therefore, when 96.42% ≤ S1 / S2 ≤ 99.75%, both energy density and reliability of the battery cell 20 can be balanced.

[0246] Along the second direction, the sidewall 2111 includes two opposing first wall portions 21111, at least one of which is the wall portion with the largest outer surface area in the housing 21. The second direction is perpendicular to the first direction. Along the second direction, the first wall portion 21111 has a second outer surface 21111a and a second inner surface 21111b. The distance between the second inner surfaces 21111b of the two first wall portions 21111 is L1, and the distance between the second outer surfaces 21111a of the two first wall portions 21111 is L2, satisfying: 97.7% ≤ L1 / L2 ≤ 99.9%. When L1 / L2 ≥ 97.7%, the ratio of the distance between the second inner surfaces 21111b of the two first wall portions 21111 to the distance between the second outer surfaces 21111a of the two first wall portions 21111 is relatively large, indicating that the thickness of the first wall portion 21111 is relatively small. This is beneficial for increasing the internal space of the housing 211, allowing the housing 211 to accommodate a larger electrode assembly 22 and more electrolyte, thereby improving the energy density of the battery cell 20. When L1 / L2 ≤ 99.9%, the ratio of the distance between the second inner surfaces 21111b of the two first wall portions 21111 to the distance between the second outer surfaces 21111a of the two first wall portions 21111 is not too large, and the thickness of the first wall portion 21111 is not too small. This ensures that the first wall portion 21111 has sufficient structural strength, which is beneficial for protecting the electrode assembly 22 and improving the reliability of the battery cell 20. Therefore, when 97.7% ≤ L1 / L2 ≤ 99.9%, the energy density and reliability of the battery cell 20 can be balanced.

[0247] The sidewall 2111 includes two first wall portions 21111 disposed opposite each other along a second direction and two second wall portions 21112 disposed opposite each other along a third direction. The first wall portions 21111 have the largest outer surface area in the outer shell 21, and the second wall portions 21112 are adjacent to the first wall portions 21111. The first direction, the second direction, and the third direction are perpendicular to each other. Along the third direction, the second wall portions 21112 have a third outer surface 21112a and a third inner surface 21112b. The distance between the third inner surfaces 21112b of the two second wall portions 21112 is L3, and the distance between the third outer surfaces 21112a of the two second wall portions 21112 is L4, satisfying: 99% ≤ L3 / L4 ≤ 99.95%. When L3 / L4 ≥ 99%, the ratio of the distance between the third inner surfaces 21112b of the two second wall portions 21112 to the distance between the third outer surfaces 21112a of the two second wall portions 21112 is relatively large, indicating that the thickness of the second wall portion 21112 is relatively small. This is beneficial for increasing the internal space of the housing 211, allowing the housing 211 to accommodate a larger electrode assembly 22 and more electrolyte, thereby improving the energy density of the battery cell 20. When L3 / L4 ≤ 99.95%, the ratio of the distance between the third inner surfaces 21112b of the two second wall portions 21112 to the distance between the third outer surfaces 21112a of the two second wall portions 21112 is not too large, and the thickness of the second wall portion 21112 is not too small. This ensures that the second wall portion 21112 has sufficient structural strength, which is beneficial for protecting the electrode assembly 22 and improving the reliability of the battery cell 20. Therefore, when 99% ≤ L3 / L4 ≤ 99.95%, the energy density and reliability of the battery cell 20 can be balanced.

[0248] The housing 211 includes a bottom wall 2112 and side walls 2111 surrounding the bottom wall 2112. One end of the side wall 2111 is connected to the bottom wall 2112, and the other end of the side wall 2111 forms an opening. Along the first direction, the distance between the inner surface of the end cap 212 and the inner surface of the bottom wall 2112 is L5, and the distance between the outer surface of the end cap 212 and the outer surface of the bottom wall 2112 is L6, satisfying: 98% ≤ L5 / L6 ≤ 99.7%. When L5 / L6 ≥ 98%, the ratio of the distance between the inner surface of the end cap 212 and the inner surface of the bottom wall 2112 to the distance between the outer surface of the end cap 212 and the outer surface of the bottom wall 2112 is relatively large, indicating that the thickness of the end cap 212 and the bottom wall 2112 is relatively small. This is beneficial for increasing the internal space of the housing 211, allowing the housing 211 to accommodate larger electrode components 22 and more electrolyte, thereby improving the energy density of the battery cell 20. When L5 / L6 ≤ 99.7%, the ratio of the distance between the inner surface of end cap 212 and the inner surface of bottom wall 2112 to the distance between the outer surface of end cap 212 and the outer surface of bottom wall 2112 will not be too large, and the thickness of end cap 212 and bottom wall 2112 will not be too small. This ensures that the thickness of end cap 212 and bottom wall 2112 has sufficient structural strength, which is beneficial for protecting electrode assembly 22 and improving the reliability of battery cell 20. Therefore, when 98% ≤ L5 / L6 ≤ 99.7%, both energy density and reliability of battery cell 20 can be balanced.

[0249] In some embodiments, the outer casing 21 is rectangular, and the electrode assembly 22 includes tabs 222 and a main body 221, with the tabs 222 protruding from the main body 221. The length of the main body 221 is A, the width of the main body 221 is B, the height of the main body 221 is C, and the volume of the outer casing 21 is V, satisfying: 83.2% ≤ A·B·C / V ≤ 94.5%. When A·B·C / V ≥ 83.2%, the volume of the electrode assembly 22 accounts for a large proportion of the volume of the outer casing 21, resulting in a high energy density for the battery cell 20. When A·B·C / V ≤ 94.5%, the volume of the electrode assembly 22 does not account for an excessively large proportion of the volume of the outer casing 21, allowing sufficient space within the outer casing 21 to accommodate the electrolyte and other electrical connection components. Therefore, when 83.2% ≤ A·B·C / V ≤ 94.5%, it is convenient to accommodate the electrolyte and other electrical connection components while also enabling the battery cell 20 to have a high energy density.

[0250] In other embodiments, the outer casing 21 is cylindrical, with an inner diameter D1 and an outer diameter D2 of the sidewall 2111, satisfying 97.7% ≤ D1 / D2 ≤ 99.9%. When D1 / D2 ≥ 97.7%, the ratio of the inner diameter to the outer diameter of the sidewall 2111 is relatively large, indicating a smaller thickness of the sidewall 2111. This is beneficial for increasing the internal space of the casing 211, allowing it to accommodate larger electrode components 22 and more electrolyte, thereby improving the energy density of the battery cell 20. When D1 / D2 ≤ 99.9%, the ratio of the inner diameter to the outer diameter of the sidewall 2111 is not too large, and the thickness of the sidewall 2111 is not too small, ensuring sufficient structural strength for the sidewall 2111, which helps protect the electrode components 22 and improves the reliability of the battery cell 20. When 97.7% ≤ D1 / D2 ≤ 99.9%, the energy density and reliability of the battery cell 20 can be balanced.

[0251] The outer casing 21 is cylindrical. The electrode assembly 22 includes tabs 222 and a main body 221, with the tabs 222 protruding from the main body 221. The radius of the main body 221 is R, the height of the main body 221 along the first direction is H, and the volume of the outer casing 21 is V, satisfying: 83.2% ≤ H·π·R 2 / V≤94.5%. When H·π·R 2 When / V≥83.2%, the volume of electrode assembly 22 accounts for a large proportion of the volume of casing 21, and the energy density of battery cell 20 is high. When H·π·R 2 When / V≤94.5%, the volume of the electrode assembly 22 will not be too large a proportion of the volume of the outer casing 21, ensuring that there is sufficient space within the outer casing 21 to accommodate the electrolyte and other electrical connection components. Therefore, when 83.2%≤H·π·R 2 When / V≤94.5%, it can not only facilitate the accommodation of electrolyte and other electrical connection components, but also enable the battery cell 20 to have a high energy density.

[0252] Both the casing 211 and the end cap 212 are made of stainless steel. Stainless steel has advantages such as corrosion resistance, high temperature resistance, and good processing performance. The casing 211 made of stainless steel has high strength, and the wall thickness of the casing 211 can be thinner while maintaining the same structural strength. Furthermore, the casing 211 made of stainless steel is not easily corroded, which helps to extend the service life of the battery cell 20.

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

[0254] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. 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, wherein, The application relates to a shell, an electrode assembly and an end cover. The shell comprises a shell body and an end cover, the shell body has an opening at at least one end in a first direction, and the end cover corresponds to the opening and seals the opening. The shell body is made of steel or titanium alloy, and comprises a side wall surrounding the electrode assembly, the side wall has a first inner surface and a first outer surface, the area of the projection of the first inner surface in the first direction is S1, the area of the projection of the first outer surface in the first direction is S2, and 96.42%<=S1 / S2<=99.75%. In a second direction, the side wall comprises two first wall portions arranged oppositely, at least one of the first wall portions is the wall portion with the largest outer surface area in the shell, and the second direction is perpendicular to the first direction.

2. The battery cell of claim 1, wherein, In the second direction, the first wall portion has a second outer surface and a second inner surface, the distance between the second inner surfaces of the two first wall portions is L1, the distance between the second outer surfaces of the two first wall portions is L2, and 97.7%<=L1 / L2<=99.9%. The thickness of the first wall portion is H1, and 0.05mm<=H1<=0.3mm.

3. The battery cell of claim 2, wherein, The second direction is the width direction of the shell, and 10mm<=L2<=100mm.

4. The battery cell of claim 2 or 3, wherein, The side wall comprises two first wall portions arranged oppositely in a second direction and two second wall portions arranged oppositely in a third direction, the first wall portion is the wall portion with the largest outer surface area in the shell, the second wall portion is adjacent to the first wall portion, and the first direction, the second direction and the third direction are perpendicular to each other.

5. The battery cell of any one of claims 1-4, wherein, In the third direction, the second wall portion has a third outer surface and a third inner surface, the distance between the third inner surfaces of the two second wall portions is L3, the distance between the third outer surfaces of the two second wall portions is L4, and 99%<=L3 / L4<=99.95%. The thickness of the second wall portion is H2, and 0.05mm<=H2<=0.4mm.

6. The battery cell of claim 5, wherein, The third direction is the length direction of the shell, and 100mm<=L4<=400mm.

7. The battery cell of claim 5 or 6, wherein, The shell body comprises a bottom wall, the side wall is arranged around the bottom wall, one end of the side wall is connected to the bottom wall, and the other end of the side wall forms the opening.

8. The battery cell of any one of claims 1-7, wherein, In the first direction, the distance between the inner surface of the end cover and the inner surface of the bottom wall is L5, the distance between the outer surface of the end cover and the outer surface of the bottom wall is L6, and 98%<=L5 / L6<=99.7%. The thickness of the end cover is H3, and 0.2mm<=H3<=1.2mm.

9. The battery cell of claim 8, wherein, The thickness of the bottom wall is H4, and 0.2mm<=H4<=1mm.

10. The battery cell of claim 8 or 9, wherein, The first direction is the height direction of the shell, and 70mm<=L6<=400mm.

11. The battery cell of any one of claims 8-10, wherein, The shell is in a cylindrical shape, the inner diameter of the side wall is D1, the outer diameter of the side wall is D2, and 97.7%<=D1 / D2<=99.9%.

12. The battery cell of claim 1, wherein, 10mm<=D2<=400mm.

13. The battery cell of claim 12, wherein, ​ 14. The battery cell of any one of claims 1-11, wherein, The shell is cuboid, the electrode assembly comprises a tab and a main body, the tab protrudes from the main body; The length of the main body is A, the width of the main body is B, the height of the main body is C, and the volume of the shell is V, which satisfies: 83.2%≤A·B·C / V≤94.5%.

15. The battery cell of claim 1, 12, or 13, wherein, The shell is cylindrical, the electrode assembly comprises a tab and a main body, the tab protrudes from the main body; The radius of the main body part is R, the height of the main body part in the first direction is H, and the volume of the shell is V, satisfying: 83.2%≤H·π·R 2 / V≤94.5%.

16. The battery cell of any one of claims 1-15, wherein, The steel material is stainless steel.

17. The battery cell of any one of claims 1-16, wherein, The material of the end cover is steel material or titanium alloy material.

18. A battery, wherein, The battery cell according to any one of claims 1-17.

19. An electrical device, comprising: The battery cell according to any one of claims 1-17 is used to provide electric energy for the electric device.

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