Battery monomer, battery and electric equipment

Abstract

The utility model provides a battery monomer, a battery and electric equipment. The battery monomer comprises a shell and an electrode assembly, the shell comprises a shell body and end covers, at least one end of the shell body along a first direction is provided with an opening, the end covers are in one-to-one correspondence with the openings, and the end covers seal the openings. An electrode assembly is housed within the housing. The shell is made of a steel material or a titanium alloy material, the shell comprises a side wall arranged around the electrode assembly, the side wall is provided with a first inner surface and a first outer surface, the area of a region defined by the projection of the first inner surface is S1, and the area of the region defined by the projection of the first outer surface is S2 in the first direction. The area of a region defined by the projection of the first outer surface 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 made of the steel material or the 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 single battery can be considered.

Description

Technical Field

[0001] The present application relates to the field of batteries, and more particularly, to a battery cell, a battery and an electrical device. Background Art

[0002] Batteries are widely used in the new energy field, such as electric vehicles, new energy vehicles, etc. Electric vehicles and new energy vehicles have become new trends in the development of the automotive industry. The development of battery technology needs to consider various design factors simultaneously, such as performance parameters like battery life, discharge capacity, charge-discharge rate, etc. In addition, the energy density of the battery also needs to be considered. However, the current energy density of batteries is relatively low. Summary of the Utility Model

[0003] An object of the embodiments of the present application is to provide a battery cell, a battery and an electrical device, aiming to improve the problem of relatively low energy density of batteries in related technologies.

[0004] In a first aspect, the embodiments of the present application provide a battery cell. The battery cell includes a housing and an electrode assembly. The housing includes a casing and an end cap. At least one end of the casing in a first direction has an opening, and the end cap corresponds to the opening one by one, and the end cap closes the opening; the electrode assembly is accommodated in the housing; wherein, the material of the casing is steel or titanium alloy, the casing includes a side wall disposed around the electrode assembly, the side wall has a first inner surface and a first outer surface, along the first direction, the area of the region defined by the projection of the first inner surface is S1, and the area of the region defined by the projection of the first outer surface is S2, satisfying: 96.42% ≤ S1 / S2 ≤ 99.75%.

[0005] In the above technical solution, the steel material and the titanium alloy material have relatively high strength. When the structural strength of the casing is the same, the wall thickness of the casing made of steel or titanium alloy can be thinner. When S1 / S2 ≥ 96.42%, the wall thickness of the side wall is thinner, and the internal space of the casing is larger. The casing can accommodate a larger electrode assembly and more electrolyte inside. Under the same chemical material system, the volume energy density of the battery cell can be improved. When S1 / S2 ≤ 99.75%, the wall thickness of the side wall is not too thin, so that the casing has sufficient structural strength, thereby effectively protecting the electrode assembly and improving the reliability of the battery cell. Therefore, when 96.42% ≤ S1 / S2 ≤ 99.75%, the energy density and reliability of the battery cell can be balanced.

[0006] As an alternative technical solution of the embodiment of the present application, along the second direction, the side wall includes two first wall portions arranged opposite to each other, and at least one of the first wall portions is the wall portion with the largest outer surface area in the outer shell. The second direction is 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%.

[0007] In the above technical solution, when L1 / L2 ≥ 97.7%, the ratio of the distance between the second inner surfaces of the two first wall portions to the distance between the second outer surfaces of the two first wall portions is relatively large, indicating that the thickness of the first wall portion is small, which is beneficial to increasing the internal space of the housing, so that a larger electrode assembly and more electrolyte can be accommodated inside the housing, thereby being beneficial to 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 wall portions to the distance between the second outer surfaces of the two first wall portions is not too large, and the thickness of the first wall portion is not too small, so that the first wall portion has sufficient structural strength, which is beneficial to protecting the electrode assembly and improving the reliability of the battery cell. Therefore, when 97.7% ≤ L1 / L2 ≤ 99.9%, the energy density and reliability of the battery cell can be balanced.

[0008] As an alternative technical solution of the embodiment of the present application, the thickness of the first wall portion is H1, satisfying: 0.05 mm ≤ H1 ≤ 0.3 mm.

[0009] In the above technical solution, when H1 ≤ 0.3 mm, the thickness of the first wall portion is small, which is beneficial to increasing the internal space of the housing, so that a larger electrode assembly and more electrolyte can be accommodated inside the housing, thereby being beneficial to improving the energy density of the battery cell. When H1 ≥ 0.05 mm, the thickness of the first wall portion is not too small, so that the first wall portion has sufficient structural strength, which is beneficial to protecting the electrode assembly and improving the reliability of the battery cell. Therefore, when 0.05 mm ≤ H1 ≤ 0.3 mm, the energy density and reliability of the battery cell can be balanced.

[0010] As an alternative technical solution of the embodiment of the present application, the second direction is the width direction of the outer shell, and 10 mm ≤ L2 ≤ 100 mm.

[0011] In the above technical solution, when 10 mm ≤ L2 ≤ 100 mm, the width of the outer shell is of moderate size, easy to manufacture, and has strong compatibility.

[0012] As an alternative technical solution of the embodiment of the present application, the side wall includes two first wall portions oppositely arranged along the second direction and two second wall portions oppositely arranged along the third direction. The first wall portion is the wall portion with the largest outer surface area in the outer shell. The second wall portion is adjacent to the first wall portion. The first direction, the second direction, and the third direction are perpendicular to each other in pairs. Along 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, and the distance between the third outer surfaces of the two second wall portions is L4, satisfying: 99% ≤ L3 / L4 ≤ 99.95%.

[0013] In the above technical solution, when L3 / L4 ≥ 99%, the ratio of the distance between the third inner surfaces of the two second wall portions to the distance between the third outer surfaces of the two second wall portions is relatively large, indicating that the thickness of the second wall portion is relatively small, which is beneficial to increasing the internal space of the housing, so that a larger electrode assembly and more electrolyte can be accommodated inside the housing, thereby being beneficial to 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 wall portions to the distance between the third outer surfaces of the two second wall portions is not too large, and the thickness of the second wall portion is not too small, so that the second wall portion has sufficient structural strength, which is beneficial to protecting the electrode assembly and improving the reliability of the battery cell. Therefore, when 99% ≤ L3 / L4 ≤ 99.95%, the energy density and reliability of the battery cell can be taken into account.

[0014] As an alternative technical solution of the embodiment of the present application, the thickness of the second wall portion is H2, satisfying: 0.05 mm ≤ H2 ≤ 0.4 mm.

[0015] In the above technical solution, when H2 ≤ 0.4 mm, the thickness of the second wall portion is relatively small, which is beneficial to increasing the internal space of the housing, so that a larger electrode assembly and more electrolyte can be accommodated inside the housing, thereby being beneficial to improving the energy density of the battery cell. When H2 ≥ 0.05 mm, the thickness of the second wall portion is not too small, so that the second wall portion has sufficient structural strength, which is beneficial to protecting the electrode assembly and improving the reliability of the battery cell. Therefore, when 0.05 mm ≤ H2 ≤ 0.4 mm, the energy density and reliability of the battery cell can be taken into account.

[0016] As an alternative technical solution of the embodiment of the present application, the third direction is the length direction of the outer shell, and 100 mm ≤ L4 ≤ 400 mm.

[0017] In the above technical solution, when 100 mm ≤ L4 ≤ 400 mm, the length of the outer shell is of moderate size, easy to manufacture, and has strong compatibility.

[0018] As an alternative technical solution of the embodiment of the present application, 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 encloses to form the opening. Along the first direction, the distance between the inner surface of the end cover and the inner surface of the bottom wall is L5, and the distance between the outer surface of the end cover and the outer surface of the bottom wall is L6, satisfying: 98% ≤ L5 / L6 ≤ 99.7%.

[0019] In the above technical solution, when L5 / L6 ≥ 98%, the ratio of the distance between the inner surface of the end cover and the inner surface of the bottom wall to the distance between the outer surface of the end cover and the outer surface of the bottom wall is relatively large, indicating that the thicknesses of the end cover and the bottom wall are relatively small, which is beneficial to increasing the internal space of the housing, so that a larger electrode assembly and more electrolyte can be accommodated inside the housing, thereby being beneficial to 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 cover and the inner surface of the bottom wall to the distance between the outer surface of the end cover and the outer surface of the bottom wall is not too large, and the thicknesses of the end cover and the bottom wall are not too small, so that the end cover and the bottom wall have sufficient structural strength, which is beneficial to protecting the electrode assembly and improving the reliability of the battery cell. Therefore, when 98% ≤ L5 / L6 ≤ 99.7%, the energy density and reliability of the battery cell can be taken into account.

[0020] As an alternative technical solution of the embodiment of the present application, the thickness of the end cover is H3, satisfying: 0.2 mm ≤ H3 ≤ 1.2 mm.

[0021] In the above technical solution, when H3 ≤ 1.2 mm, the thickness of the end cover is relatively small, which is beneficial to increasing the internal space of the housing, so that a larger electrode assembly and more electrolyte can be accommodated inside the housing, thereby being beneficial to improving the energy density of the battery cell. When H3 ≥ 0.2 mm, the thickness of the end cover is not too small, so that the end cover has sufficient structural strength, which is beneficial to protecting the electrode assembly and improving the reliability of the battery cell. Therefore, when 0.2 mm ≤ H3 ≤ 1.2 mm, the energy density and reliability of the battery cell can be taken into account.

[0022] As an alternative technical solution of the embodiment of the present application, the thickness of the bottom wall is H4, satisfying: 0.2 mm ≤ H4 ≤ 1 mm.

[0023] In the above technical solution, when H4 ≤ 1 mm, the thickness of the bottom wall is small, which is beneficial to increasing the internal space of the housing, enabling the housing to accommodate a larger electrode assembly and more electrolyte, thus facilitating the improvement of the energy density of the battery cell. When H4 ≥ 0.2 mm, the thickness of the bottom wall is not too small, so that the bottom wall has sufficient structural strength, which is beneficial to protecting the electrode assembly and improving the reliability of the battery cell. When 0.2 mm ≤ H4 ≤ 1 mm, the energy density and reliability of the battery cell can be balanced.

[0024] As an alternative technical solution of the embodiment of the present application, the first direction is the height direction of the outer shell, and 70 mm ≤ L6 ≤ 400 mm.

[0025] In the above technical solution, when 70 mm ≤ L6 ≤ 400 mm, the length of the outer shell is of appropriate size, easy to manufacture, and has strong compatibility.

[0026] As an alternative technical solution of the embodiment of the present application, the outer shell is cylindrical, the inner diameter of the side wall is D1, and the outer diameter of the side wall is D2, satisfying: 97.7% ≤ D1 / D2 ≤ 99.9%.

[0027] In the above technical solution, when D1 / D2 ≥ 97.7%, the ratio of the inner diameter of the side wall to the outer diameter of the side wall is large, indicating that the thickness of the side wall is small, which is beneficial to increasing the internal space of the housing, enabling the housing to accommodate a larger electrode assembly and more electrolyte, thus facilitating the improvement of the energy density of the battery cell. When D1 / D2 ≤ 99.9%, the ratio of the inner diameter of the side wall to the outer diameter of the side wall is not too large, and the thickness of the side wall is not too small, so that the side wall has sufficient structural strength, which is beneficial to protecting the electrode assembly and improving the reliability of the battery cell. When 97.7% ≤ D1 / D2 ≤ 99.9%, the energy density and reliability of the battery cell can be balanced.

[0028] As an alternative technical solution of the embodiment of the present application, 10 mm ≤ D2 ≤ 400 mm.

[0029] In the above technical solution, when 10 mm ≤ D2 ≤ 400 mm, the outer diameter of the side wall is of appropriate size, easy to manufacture, and has strong compatibility.

[0030] As an alternative technical solution of the embodiment of the present application, the outer shell is rectangular parallelepiped-shaped, the electrode assembly includes a tab and a main body portion, and the tab protrudes from the main body portion; the length of the main body portion is A, the width of the main body portion is B, the height of the main body portion is C, and the volume of the outer shell is V, satisfying: 83.2% ≤ A·B·C / V ≤ 94.5%.

[0031] In the above technical solution, when A·B·C / V ≥ 83.2%, the volume of the electrode assembly accounts for a relatively large proportion of the volume of the outer shell, and the energy density of the battery cell is relatively high. When A·B·C / V ≤ 94.5%, the proportion of the volume of the electrode assembly in the volume of the outer shell is not too large, so that there is a certain space in the outer shell 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, and the battery cell can have a relatively high energy density.

[0032] As an alternative technical solution of the embodiment of the present application, the outer shell is cylindrical, the electrode assembly includes a tab and a main body, and the tab protrudes from the main body; the radius of the main body is R, the height of the main body in the first direction is H, and the volume of the outer shell is V, satisfying: 83.2% ≤ H·π·R 2 / V ≤ 94.5%.

[0033] In the above technical solution, when H·π·R 2 / V ≥ 83.2%, the volume of the electrode assembly accounts for a relatively large proportion of the volume of the outer shell, and the energy density of the battery cell is relatively high. When H·π·R 2 / V ≤ 94.5%, the proportion of the volume of the electrode assembly in the volume of the outer shell is not too large, so that there is a certain space in the outer shell to accommodate the electrolyte and other electrical connection components. Therefore, when 83.2% ≤ H·π·R 2 / V ≤ 94.5%, it is convenient to accommodate the electrolyte and other electrical connection components, and the battery cell can have a relatively high energy density.

[0034] As an alternative technical solution of the embodiment of the present application, the steel material is stainless steel.

[0035] In the above technical solution, stainless steel has the advantages of corrosion resistance, high temperature resistance, good processing performance, etc. The housing made of stainless steel has relatively high strength. Under the condition of the same structural strength of the housing, the wall thickness of the housing can be thinner. Moreover, the housing made of stainless steel is not easily corroded, which is beneficial to improving the service life of the battery cell.

[0036] As an alternative technical solution of the embodiment of the present application, the material of the end cover is steel or titanium alloy.

[0037] In the above technical solution, the steel material and the titanium alloy material have relatively high strength. Under the condition of the same structural strength of the end cover, the thickness of the end cover made of steel or titanium alloy can be thinner, which is beneficial to increasing the internal space of the outer shell, so that a larger electrode assembly and more electrolyte can be accommodated inside the outer shell. Under the same chemical material system, the volume energy density of the battery cell can be improved.

[0038] In a second aspect, an embodiment of the present application further provides a battery, which includes the above-mentioned battery cell.

[0039] In a third aspect, an embodiment of the present application further provides an electrical device, which includes the above-mentioned battery cell, and the battery cell is used to provide electrical energy for the electrical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation of the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0041] Figure 1 Structural schematic diagram of a vehicle provided by some embodiments of the present application;

[0042] Figure 2 Explosion diagram of a battery provided by some embodiments of the present application;

[0043] Figure 3 Explosion diagram of a battery cell provided by some embodiments of the present application;

[0044] Figure 4 Structural schematic diagram of a battery cell provided by some embodiments of the present application;

[0045] Figure 5 Top view schematic diagram of a housing provided by some embodiments of the present application;

[0046] Figure 6 Front view schematic diagram of a battery cell provided by some embodiments of the present application;

[0047] Figure 7 For Figure 6 Cross-sectional view at position A-A in

[0048] Figure 8 Top view schematic diagram of a battery cell provided by some embodiments of the present application;

[0049] Figure 9 For Figure 8 Cross-sectional view at position B-B in

[0050] Figure 10 Structural schematic diagram of a battery cell provided by some other embodiments of the present application;

[0051] Figure 11 Explosion diagram of a battery cell provided by some other embodiments of the present application;

[0052] Figure 12 A top view schematic diagram of the housing provided for some other embodiments of the present application;

[0053] Figure 13 A top view schematic diagram of the battery cell provided for some other embodiments of the present application;

[0054] Figure 14 is Figure 13 A cross-sectional view taken at the C-C position in

[0055] Reference numerals: 10 - housing; 11 - first part; 12 - second part; 20 - battery cell; 21 - outer shell; 211 - housing; 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 portion; 222 - tab; 24 - electrode terminal; 100 - battery; 200 - controller; 300 - motor; 1000 - vehicle. Detailed Embodiments

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0057] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs; the terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "including" and "having" and any variations thereof in the specification, claims, and drawings of the present application are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the specification, claims, or drawings of the present application are used to distinguish different objects and are not used to describe a specific order or primary-secondary relationship.

[0058] Referring to "embodiments" in the present application means that the specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase appears at various positions in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments.

[0059] In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "linked", and "attached" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0060] The term "and / or" in the present application is merely a relational description of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in the present application generally represents an "or" relationship between the associated objects before and after.

[0061] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, in different embodiments, the detailed descriptions of the same components are omitted. It should be understood that the thickness, length, width, and other dimensions of various components shown in the drawings in the embodiments of the present application, as well as the overall thickness, length, width, and other dimensions of the integrated device, are only for illustrative purposes and should not constitute any limitation to the present application.

[0062] The "plurality" mentioned in the present application refers to two or more (including two).

[0063] In the embodiments of the present application, the battery cell can be a secondary battery, which refers to a battery cell that can be activated by charging after discharging to continue to be used.

[0064] The battery cell can be a lithium-ion battery, a sodium-ion battery, a sodium-lithium-ion battery, a lithium metal battery, a sodium metal battery, a lithium-sulfur battery, a magnesium-ion battery, a nickel-metal hydride battery, a nickel-cadmium battery, a lead-acid battery, etc., and the embodiments of the present application are not limited thereto.

[0065] The battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are embedded and extracted back and forth between the positive electrode and the negative electrode. The separator is disposed between the positive electrode and the negative electrode, which can play a role in preventing short circuit between the positive and negative electrodes to a certain extent and at the same time allow the active ions to pass through.

[0066] In some embodiments, the positive electrode can be a positive electrode tab, and the positive electrode tab can include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0067] As an example, the positive electrode current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode active material is disposed on either or both of the two opposite surfaces of the positive electrode current collector.

[0068] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium, etc. can be used. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as substrates of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0069] As an example, the positive electrode active material can include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials can also be used. These positive electrode active materials can be used alone or in combination of two or more. Among them, examples of lithium-containing phosphates can include but are not limited to lithium iron phosphate (such as LiFePO4 (which can also be abbreviated as LFP)), composites of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), composites of lithium manganese phosphate and carbon, lithium manganese iron phosphate, composites of lithium manganese iron phosphate and carbon, etc. Examples of lithium transition metal oxides can 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, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which can also be abbreviated as NCM 333 )、LiNi 0.5 Co 0.2 Mn 0.3 O2 (which can also be abbreviated as NCM 523 )、LiNi 0.5 Co 0.25 Mn 0.25 O2 (which can also be abbreviated as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O2 (which can also be abbreviated as NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O2 (which can also be abbreviated as NCM 811) at least one of lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and its modified compounds, etc.

[0070] In some embodiments, the positive electrode may be made of porous metal. The porous metal may be porous nickel, porous copper, porous aluminum, porous alloy, etc. When the porous metal is used as the positive electrode, the positive electrode active material may not be provided on the surface of the porous metal, or of course, the positive electrode active material may be provided. As an example, a lithium source material, potassium metal or sodium metal may also be filled and / or deposited in the porous metal, and the lithium source material is lithium metal and / or lithium-rich material.

[0071] In some embodiments, the negative electrode may be a negative electrode plate, and the negative electrode plate may include a negative electrode current collector.

[0072] As an example, the negative electrode current collector may be made of a metal foil, porous metal or composite current collector. For example, as the metal foil, aluminum or stainless steel with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrode, nickel or titanium, etc. may be used. The porous metal may be porous nickel, porous copper, porous aluminum, porous alloy, etc. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (such as 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.).

[0073] As an example, the negative electrode plate may include a negative electrode current collector and a negative electrode active material provided on at least one surface of the negative electrode current collector.

[0074] As an example, the negative electrode current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode active material is provided on any one or both of the two opposite surfaces of the negative electrode current collector.

[0075] As an example, the negative electrode active material may be a negative electrode active material for a battery cell known in the art. 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 material, tin-based material, and lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compound, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material may be selected from at least one of elemental tin, tin oxide compound, and tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as the negative electrode active material of the battery may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0076] In some embodiments, the material of the positive current collector can be aluminum, and the material of the negative current collector can be copper.

[0077] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0078] In some embodiments, the separator is a separator membrane. The types of the separator membrane can be various, and any well-known porous structure separator membrane with good chemical stability and mechanical stability can be selected.

[0079] As an example, the material of the separator membrane can include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator membrane can be a single-layer film or a multi-layer composite film. When the separator membrane is a multi-layer composite film, the materials of each layer can be the same or different. The separator can be a single component located between the positive and negative electrodes, or can be attached to the surfaces of the positive and negative electrodes.

[0080] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive electrode and the negative electrode, and simultaneously functions to transport ions and isolate the positive and negative electrodes.

[0081] In some embodiments, the battery cell further includes an electrolyte, and the electrolyte functions to conduct ions between the positive and negative electrodes. The electrolyte can be liquid, gel-like, or solid. Among them, the liquid electrolyte includes electrolyte salts and solvents.

[0082] In some embodiments, the electrolyte salts can 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 bis(oxalato)borate, lithium difluoro bis(oxalato)phosphate, and lithium tetrafluorooxalate phosphate.

[0083] In some embodiments, the solvents can include at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene 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 can also be an ether solvent. The ether solvent can include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether, and crown ether.

[0084] Among them, the gel-like electrolyte includes a polymer as the skeleton network of the electrolyte, combined with an ionic liquid-lithium salt.

[0085] Among them, the solid electrolyte includes polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0086] As an example, the polymer solid electrolyte can be polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, single-ion polymer, polyionic liquid-lithium salt, cellulose, etc.

[0087] As an example, the inorganic solid electrolyte can include oxide solid electrolytes (crystalline perovskite, sodium superionic conductor, garnet, amorphous LiPON film), sulfide solid electrolytes (crystalline lithium superionic conductor (lithium germanium phosphorus sulfur, argyrodite), amorphous sulfide), and one or more of halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0088] As an example, the composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to the polymer solid electrolyte.

[0089] In some embodiments, the electrode assembly has a wound structure. The positive electrode sheet and the negative electrode sheet are wound into a wound structure.

[0090] In some embodiments, the electrode assembly has a laminated structure.

[0091] As an example, multiple positive electrode sheets and multiple negative electrode sheets can be respectively provided, and the multiple positive electrode sheets and the multiple negative electrode sheets are alternately laminated.

[0092] As an example, multiple positive electrode sheets can be provided, and the negative electrode sheet is folded to form multiple folded segments arranged in a laminated manner, and a positive electrode sheet is clamped between adjacent folded segments.

[0093] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form multiple folded segments arranged in a laminated manner.

[0094] As an example, multiple separators can be provided and are respectively arranged between any adjacent positive electrode sheets or negative electrode sheets.

[0095] As an example, the separators can be continuously provided and are arranged between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0096] In some embodiments, the shape of the electrode assembly can be cylindrical, flat, prismatic, etc.

[0097] In some embodiments, the electrode assembly is provided with tabs, and the tabs can conduct current out of the electrode assembly. The tabs include positive tabs and negative tabs.

[0098] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as the electrode assembly and the electrolyte. The housing can be a steel shell, an aluminum shell, a plastic shell (such as polypropylene), a composite metal shell (such as a copper-aluminum composite housing), or an aluminum-plastic film, etc.

[0099] 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, the housing can protect the electrode assembly and to a certain extent prevent, for example, electrolyte leakage. When the housing is a non-sealed structure, the housing can protect the electrode assembly, and a sealed bag may further be included between the housing and the electrode assembly. The sealed bag is used to encapsulate components such as the electrode assembly and the electrolyte. Specifically, the sealed bag can be a bag-shaped insulating part or an aluminum-plastic film.

[0100] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. The prismatic battery cell includes, but is not limited to, a square shell battery cell, a blade-shaped battery cell, a multi-prismatic battery, and the multi-prismatic battery is, for example, a hexagonal prism battery, etc.

[0101] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide a higher voltage and capacity.

[0102] In some embodiments, the battery can be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0103] In some embodiments, the battery can be a battery pack. The battery pack includes a box body and battery cells, and the battery cells or battery modules are accommodated in the box body.

[0104] In some embodiments, the box body can be part of the chassis structure of a vehicle. For example, part of the box body can become at least part of the floor of the vehicle, or part of the box body can become at least part of the cross beam and longitudinal beam of the vehicle.

[0105] In some embodiments, the battery can be an energy storage device. The energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0106] Currently, from the perspective of the development of the market situation, the application of batteries is becoming more and more extensive. Batteries are not only applied to energy storage power systems such as hydroelectric power stations, thermal power stations, wind power stations, and solar power stations, but also widely applied to electric transportation means such as electric bicycles, electric motorcycles, and electric vehicles, as well as multiple fields such as military equipment and aerospace. With the continuous expansion of the application fields of batteries, the market demand is also continuously increasing.

[0107] The development of battery technology needs to consider various design factors simultaneously. For example, performance parameters such as battery life, discharge capacity, charge and discharge rate, etc. In addition, the energy density of the battery also needs to be considered. However, the current energy density of the battery is relatively low.

[0108] In the prior art, the housing of a battery cell is generally made of aluminum. The strength of the aluminum material is relatively low, resulting in the need for a relatively large wall thickness of the housing to have sufficient strength. The relatively large wall thickness of the housing makes the internal space of the housing smaller, resulting in a relatively low energy density of the battery cell. If the wall thickness of the housing is directly reduced, it will lead to insufficient strength of the housing, resulting in relatively poor reliability of the battery cell.

[0109] In view of this, an embodiment of the present application provides a battery cell. The battery cell includes a housing and an electrode assembly. The housing includes a shell and an end cap. At least one end of the shell in the first direction has an opening, and the end cap corresponds to the opening one by one, and the end cap closes the opening. The electrode assembly is accommodated in the housing. Among them, the material of the shell is steel or titanium alloy. The shell includes a side wall surrounding the electrode assembly, and the side wall has a first inner surface and a first outer surface. Along the first direction, the area of the region defined by the projection of the first inner surface is S1, and the area of the region defined by the projection of the first outer surface is S2, satisfying: 96.42% ≤ S1 / S2 ≤ 99.75%.

[0110] The strength of steel and titanium alloy materials is relatively high. Under the condition of the same structural strength of the shell, the wall thickness of the shell made of steel or titanium alloy materials can be thinner. When S1 / S2 ≥ 96.42%, the wall thickness of the side wall is relatively thin, and the internal space of the shell is relatively large. A larger electrode assembly and more electrolyte can be accommodated inside the shell. Under the same chemical material system, the volume energy density of the battery cell can be improved. When S1 / S2 ≤ 99.75%, the wall thickness of the side wall is not too thin, so that the shell has sufficient structural strength, thereby effectively protecting the electrode assembly and improving the reliability of the battery cell. Therefore, when 96.42% ≤ S1 / S2 ≤ 99.75%, the energy density and reliability of the battery cell can be taken into account.

[0111] The battery cell disclosed in the embodiment of the present application can be but is not limited to being used in electrical equipment such as vehicles, ships or aircraft. A power supply system of the electrical equipment can be composed of the battery cell, battery, etc. disclosed in the present application. In this way, it is beneficial to improve the energy density of the battery cell and extend the battery life of the electrical equipment.

[0112] The electrical equipment can be a vehicle, a mobile phone, a portable device, a laptop, a ship, a spacecraft, an electric toy, an electric tool, etc. Spacecraft include airplanes, rockets, space shuttles, spaceships, etc.; Electric toys include stationary or mobile electric toys, such as game consoles, electric vehicle toys, electric ship toys, electric airplane toys, etc.; Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, which can include but are not limited to electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact electric drills, concrete vibrators, and electric planers, etc.

[0113] For the convenience of description, the following embodiments will take the electrical equipment as the vehicle 1000 as an example for illustration.

[0114] Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of the vehicle 1000 provided by some embodiments of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle, or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid vehicle, an extended-range vehicle, etc. A battery 100 is disposed inside the vehicle 1000, and the battery 100 can be disposed at the bottom, the head, or the tail of the vehicle 1000. The battery 100 can be used to supply power to the vehicle 1000. For example, the battery 100 can be used as the operating power source of the vehicle 1000. The vehicle 1000 can 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, it is used for the working power requirements during the start, navigation, and driving of the vehicle 1000.

[0115] In some embodiments of the present application, the battery 100 can not only be used as the operating power source of the vehicle 1000, but also be used as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0116] Please refer to Figure 2 , Figure 2 which is an exploded view of the battery 100 provided by some embodiments of the present application. The battery 100 includes a box body 10 and battery cells 20, and the battery cells 20 are accommodated in the box body 10.

[0117] Among them, the box body 10 is used to provide an accommodation space for the battery cell 20, and the box body 10 can adopt various structures. In some embodiments, the box body 10 may include a first part 11 and a second part 12. The first part 11 and the second part 12 cover each other, and the first part 11 and the second part 12 jointly define an accommodation 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. The first part 11 covers the open side of the second part 12 so that the first part 11 and the second part 12 jointly define an accommodation space; the first part 11 and the second part 12 may also 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.

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

[0119] In the battery 100, there may be multiple battery cells 20. The multiple battery cells 20 can be connected in series, in parallel, or in a hybrid connection. A hybrid connection means that there are both series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 can be directly connected in series, in parallel, or in a hybrid connection together, and then the whole formed by the multiple battery cells 20 is accommodated in the box body 10; of course, the battery 100 can also be in the form that multiple battery cells 20 are first connected in series, in parallel, or in a hybrid connection to form battery modules, and then the multiple battery modules are connected in series, in parallel, or in a hybrid connection to form a whole and are accommodated in the box body 10.

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

[0121] Among them, 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 not limited thereto. The battery cell 20 can be in the shape of a cylinder, a flat body, a cuboid, or other shapes, etc. Exemplarily, in Figure 2 the battery cell 20 has a cuboid structure.

[0122] Please refer to Figure 3 、 Figure 4 and Figure 5 , Figure 3 which is an exploded view of the battery cell 20 provided in some embodiments of the present application. Figure 4 which is a schematic structural diagram of the battery cell 20 provided in some embodiments of the present application. Figure 5A top view schematic diagram of the housing 211 provided by some embodiments of the present application. Some embodiments of the present application provide a battery cell 20, which includes a housing 21 and an electrode assembly 22. The housing 21 includes a housing body 211 and end caps 212. At least one end of the housing body 211 in the first direction has an opening, and the end caps 212 correspond to the openings one by one, and the end caps 212 close the openings. The electrode assembly 22 is accommodated in the housing 21. Among them, the material of the housing body 211 is steel or titanium alloy. The housing body 211 includes a side wall 2111 disposed around the electrode assembly 22, and the side wall 2111 has a first inner surface 2111b and a first outer surface 2111a. Along the first direction, the area of the region defined by the projection of the first inner surface 2111b is S1, and the area of the region defined by the projection of the first outer surface 2111a is S2, satisfying: 96.42% ≤ S1 / S2 ≤ 99.75%.

[0123] The battery cell 20 refers to the smallest unit that makes up the battery 100.

[0124] Among them, the housing 21 can also be used to accommodate an electrolyte, for example, an electrolytic solution. The housing 21 can be in various structural forms, such as a cylinder, a cuboid or a prism structure, etc. The housing 21 includes a housing body 211 and end caps 212. In some embodiments, the housing body 211 has a receiving space with an opening at one end, and the receiving space is used to accommodate the electrode assembly 22. The end caps 212 are connected to the housing body 211 and close the opening. In other embodiments, the housing body 211 has a receiving space with openings at both ends, and the receiving space is used to accommodate the electrode assembly 22. Two end caps 212 are respectively connected to both ends of the housing body 211 and close the two openings.

[0125] The end cap 212 refers to a component that covers the opening of the housing 211 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cap 212 can be adapted to the shape of the housing 211 to fit the housing 211. Optionally, the end cap 212 can be made of a material with a certain hardness and strength (such as aluminum alloy). In this way, the end cap 212 is not easily deformed when subjected to extrusion and collision, enabling the battery cell 20 to have higher structural strength and improved reliability. The material of the end cap 212 can include but is not limited to copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. An electrode terminal 24 is also provided on the end cap 212. The electrode terminal 24 is used to electrically connect with the tab 222 of the electrode assembly 22 to input or output the electrical energy of the battery cell 20. The electrode terminal 24 and the tab 222 can be directly connected. For example, the electrode terminal 24 is directly welded to the tab 222. The electrode terminal 24 and the tab 222 can also be indirectly connected. For example, the electrode terminal 24 and the tab 222 are indirectly connected through a current collector member. The battery cell 20 further includes an insulating member. The insulating member is disposed inside the end cap 212. The insulating member can be used to isolate the electrical connection components inside the housing 211 from the end cap 212 to reduce the risk of short circuit. Exemplarily, the insulating member can be plastic, rubber, etc.

[0126] The housing 211 is a component used to cooperate with the end cap 212 to form the internal environment of the battery cell 20. Among them, the formed internal environment can be used to accommodate the electrode assembly 22, the 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 is covered on the opening to form the internal environment of the battery cell 20. Without limitation, the end cap 212 and the housing 211 can also be integrated. Specifically, the end cap 212 and the housing 211 can first form a common joint surface before other components are inserted into the housing. When it is necessary to encapsulate the inside of the housing 211, the end cap 212 is then covered on the housing 211. The housing 211 can be of 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.

[0127] When assembling the battery cell 20, the electrode assembly 22 can be first placed into the housing 211, and the electrolyte can be filled into the housing 211. Then, the end cap 212 is covered on the opening of the housing 211 to complete the assembly of the battery cell 20.

[0128] The outer shell 21 can be of various shapes, such as a cylinder, a cuboid, etc. The shape of the outer shell 21 can be determined according to the specific shape of the electrode assembly 22. For example, if the electrode assembly 22 is a cylinder structure, the outer shell 21 can be selected as a cylinder structure; if the electrode assembly 22 is a cuboid structure, the outer shell 21 can be selected as a cuboid structure. Exemplarily, in Figure 3 and Figure 4 the outer shell 21 is a cuboid structure.

[0129] The electrode assembly 22 is a component in the battery cell 20 where an electrochemical reaction occurs. The housing 211 can contain one or more electrode assemblies 22. The electrode assembly 22 is mainly formed by winding or laminating a positive electrode plate and a negative electrode plate, and usually a separator is provided between the positive electrode plate and the negative electrode plate. The parts of the positive electrode plate and the negative electrode plate with active materials constitute the main body 221 of the electrode assembly 22, and the parts of the positive electrode plate and the negative electrode plate without active materials respectively constitute the electrode tabs 222. The positive electrode tab and the negative electrode tab can be located at one end of the main body 221 together or at both ends of the main body 221 respectively. During the charging and discharging process of the battery 100, the positive electrode active material and the negative electrode active material react with the electrolyte.

[0130] Among them, in Figure 3 and Figure 4 the battery cell 20 includes two electrode terminals 24, and the two electrode terminals 24 are both insulatingly mounted on the end cap 212. Correspondingly, the electrode assembly 22 forms two electrode tabs 222 at one end of the main body 221 along the first direction, and the polarities of the two electrode tabs 222 are opposite, so that the positive and negative electrodes of the electrode assembly 22 can be input or output respectively, and the two electrode tabs 222 are electrically connected to the two electrode terminals 24 respectively. It should be noted that the electrode tab 222 of the electrode assembly 22 is a component formed by laminating and connecting the regions on the positive electrode plate where the positive electrode active material layer is not coated or the regions on the negative electrode plate where the negative electrode active material layer is not coated. If the electrode tab 222 is used to output the positive electrode of the electrode assembly 22, the electrode tab 222 is a component formed by laminating and connecting the regions on the positive electrode plate where the positive electrode active material layer is not coated; if the electrode tab 222 is used to output the negative electrode of the electrode assembly 22, the electrode tab 222 is a component formed by laminating and connecting the regions on the negative electrode plate where the negative electrode active material layer is not coated.

[0131] Of course, the structure of the battery cell 20 is not limited to this. In other embodiments, the two electrode terminals 24 can also be provided on two wall portions of the outer shell 21. One electrode terminal 24 can be provided on the end cap 212, and the other electrode terminal 24 can be provided on the housing 211, or both electrode terminals 24 can be provided on the housing 211.

[0132] Optionally, the number of electrode assemblies 22 housed in the housing 21 can be one or more. Exemplarily, the number of electrode assemblies 22 housed in the housing 21 can also be one, two, three, four, five, six, seven, eight, etc.

[0133] Among them, the electrode terminal 24 functions to input or output the electric energy of the battery cell 20. The electrode terminal 24 is electrically connected to the tab 222 to input or output the electric energy of the battery cell 20. It should be noted that the electrode terminal 24 is insulated and installed 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.

[0134] Optionally, the material of the electrode terminal 24 can also be various. For example, the material of the electrode terminal 24 can be copper, iron, aluminum, steel, or aluminum alloy, etc.

[0135] In some embodiments, the battery cell 20 can also include two current collecting members. Both of the two current collecting members are disposed in the housing 21. Each current collecting member is used to connect an electrode terminal 24 and the tab 222 with the same polarity in the electrode assembly 22 to achieve the electrical connection between the electrode terminal 24 and the electrode assembly 22, which is beneficial to reducing the assembly difficulty between the tab 222 and the electrode terminal 24.

[0136] Exemplarily, the material of the current collecting member can also be various. For example, the material of the current collecting member can be copper, iron, aluminum, steel, or aluminum alloy, etc.

[0137] Please refer to Figure 7 , the first direction is the Z direction shown in the figure.

[0138] The steel material can be carbon steel or stainless steel. The carbon steel can be low-carbon steel, medium-carbon steel, or high-carbon steel.

[0139] The titanium alloy material refers to various alloy metals made of titanium and other metals. The titanium alloy has high strength, good corrosion resistance, and high heat resistance.

[0140] The side wall 2111 surrounds the outside of the electrode assembly 22. When the housing 21 is in a cuboid structure, the side wall 2111 includes a plurality of wall portions that are connected end to end. When the housing 21 is in a cylindrical structure, the side wall 2111 is the peripheral wall of the housing 21.

[0141] The first inner surface 2111b is the surface of the side wall 2111 facing the electrode assembly 22. When the housing 21 is in a cuboid structure, the first inner surface 2111b includes the inner surfaces of a plurality of wall portions. When the housing 21 is in a cylindrical structure, the first inner surface 2111b is the inner peripheral surface of the peripheral wall.

[0142] The first outer surface 2111a is the surface of the side wall 2111 facing away from the electrode assembly 22. When the housing 21 has a cuboid structure, the first outer surface 2111a includes the outer surfaces of a plurality of wall portions. When the housing 21 has a cylindrical structure, the first outer surface 2111a is the outer peripheral surface of the circumferential wall.

[0143] S1 is the area of the region defined by the projection of the first inner surface 2111b in the first direction. Please refer to Figure 5 , Figure 5 where S1 is marked with a mesh line. It should be noted that the mesh line here is only for facilitating the display of S1 and does not represent any physical meaning.

[0144] S2 is the area of the region defined by the projection of the first outer surface 2111a in the first direction, and S2 includes S1. Please refer to Figure 5 , Figure 5 where the area S3 defined by the projection of the first inner surface 2111b in the first direction and the projection of the first outer surface 2111a in the first direction is marked with a cross-hatch line. It should be noted that the cross-hatch line here is only for facilitating the display of S3 and does not represent any physical meaning. Among them, S2 = S1 + S3.

[0145] S1 / S2 represents the ratio of the area of the region defined by the projection of the first inner surface 2111b in the first direction to the area of the region defined by the projection of the first outer surface 2111a in the first direction.

[0146] The ratio of the area of the region defined by the projection of the first inner surface 2111b in the first direction to the area of the region defined by the projection of the first outer surface 2111a in 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.

[0147] The steel material and the titanium alloy material have relatively high strength. When the structural strength of the housing 211 is the same, the wall thickness of the housing 211 made of the steel material or the titanium alloy material can be thinner. When S1 / S2 ≥ 96.42%, the wall thickness of the side wall 2111 is thinner, and the internal space of the housing 211 is larger. Larger electrode assemblies 22 and more electrolytes can be accommodated inside the housing 211. Under the same chemical material system, the volume energy density of the battery cell 20 can be increased. When S1 / S2 ≤ 99.75%, the wall thickness of the side wall 2111 is not too thin, so that the housing 211 has sufficient structural strength, thereby effectively protecting the electrode assembly 22 and improving the reliability of the battery cell 20. Therefore, when 96.42% ≤ S1 / S2 ≤ 99.75%, the energy density and reliability of the battery cell 20 can be taken into account.

[0148] Please refer to Figure 3 、 Figure 4 、 Figure 5 、 Figure 6 and Figure 7 , Figure 6 which is the front view schematic diagram of the battery cell 20 provided by some embodiments of the present application. Figure 7 is Figure 6 the cross-sectional view at the A-A position in. In some embodiments, along the second direction, the side wall 2111 includes two first wall portions 21111 arranged oppositely, and at least one first wall portion 21111 is the wall portion with the largest outer surface area of the outer shell 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%.

[0149] The first wall portion 21111 is the wall portion with the largest outer surface area of the outer shell 21, commonly known as the large surface. The two first wall portions 21111 are arranged oppositely along the second direction. Please refer to Figure 7 ,where the second direction is the X direction shown in the figure. The second direction is perpendicular to the first direction.

[0150] The second outer surface 21111a is the surface of the first wall portion 21111 facing away from the electrode assembly 22, and the second inner surface 21111b is the surface of the first wall portion 21111 facing the electrode assembly 22. Along the second direction, the second outer surface 21111a and the second inner surface 21111b are arranged oppositely.

[0151] The first outer surface 2111a includes the second outer surfaces 21111a of two first wall portions 21111, and the first inner surface 2111b includes the second inner surfaces 21111b of two first wall portions 21111.

[0152] L1 represents the distance of the second inner surfaces 21111b of two first wall portions 21111 in the second direction. When measuring, multiple measurements can be taken and the average value can be used as L1.

[0153] L2 represents the distance of the second outer surfaces 21111a of two first wall portions 21111 in the second direction. When measuring, multiple measurements can be taken and the average value can be used as L1.

[0154] L1 / L2 represents the ratio of the distance of the second inner surfaces 21111b of two first wall portions 21111 in the second direction to the distance of the second outer surfaces 21111a of two first wall portions 21111 in the second direction.

[0155] The ratio of the distance of the second inner surfaces 21111b of two first wall portions 21111 in the second direction to the distance of the second outer surfaces 21111a of two first wall portions 21111 in 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.

[0156] When L1 / L2 ≥ 97.7%, the ratio of the distance between the second inner surfaces 21111b of two first wall portions 21111 to the distance of the second outer surfaces 21111a of two first wall portions 21111 is relatively large, indicating that the thickness of the first wall portion 21111 is smaller, which is beneficial to increasing the internal space of the housing 211, enabling the housing 211 to accommodate a larger electrode assembly 22 and more electrolyte, thereby being beneficial to 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 two first wall portions 21111 to the distance of the second outer surfaces 21111a of two first wall portions 21111 is not too large, and the thickness of the first wall portion 21111 is not too small, so that the first wall portion 21111 has sufficient structural strength, which is beneficial to 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.

[0157] Please refer to Figure 3 、 Figure 4 、 Figure 5 、 Figure 6 and Figure 7, in some embodiments, the thickness of the first wall portion 21111 is H1, satisfying: 0.05 mm ≤ H1 ≤ 0.3 mm.

[0158] H1 represents the thickness of the first wall portion 21111. During measurement, it can be measured multiple times and the average value can be taken as H1.

[0159] The thickness of the first wall portion 21111 can be: H1 = 0.05 mm, 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.22 mm, 0.25 mm, 0.28 mm, 0.3 mm, etc.

[0160] When H1 ≤ 0.3 mm, the thickness of the first wall portion 21111 is relatively small, which is beneficial to increasing the internal space of the housing 211, so that a larger electrode assembly 22 and more electrolyte can be accommodated inside the housing 211, thereby being beneficial to 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, so that the first wall portion 21111 has sufficient structural strength, which is beneficial to protecting the electrode assembly 22 and improving the reliability of the battery cell 20. Therefore, when 0.05 mm ≤ H1 ≤ 0.3 mm, the energy density and reliability of the battery cell 20 can be taken into account.

[0161] In some embodiments, a pressure relief mechanism is further provided on the outer shell 21. The pressure relief mechanism is a component used to open when the internal pressure or temperature of the battery cell 20 reaches the detonation pressure to release the internal pressure of the battery cell 20. The pressure relief mechanism is a component installed on a wall portion of the outer shell 21, and the pressure relief mechanism is separately provided and connected to a wall portion of the outer shell 21 (during manufacturing, a pressure relief hole is opened on a wall portion of the outer shell 21, and the pressure relief mechanism and a wall portion of the outer shell 21 are separately provided and finally connected together). For example, the pressure relief mechanism is an explosion-proof film installed on a wall portion of the outer shell 21.

[0162] Optionally, the material of the pressure relief mechanism includes steel or nickel, and the material of the wall portion of the housing 21 where the pressure relief mechanism is provided is steel. The material of the pressure relief mechanism can be carbon steel or stainless steel. Carbon steel can be low-carbon steel, medium-carbon steel, or high-carbon steel. For example, the material of the pressure relief mechanism can be: 304 stainless steel, 305 stainless steel, 316 stainless steel, nickel, etc. By making the material of the pressure relief mechanism include steel or nickel and the material of the wall portion of the housing 21 where the pressure relief mechanism is provided be steel, on the one hand, it can effectively improve the structural strength of the wall portion of the housing 21 where the pressure relief mechanism is provided and the pressure relief mechanism, reduce the risk of deformation of the wall portion of the housing 21 where the pressure relief mechanism is provided and the pressure relief mechanism under stress, is beneficial to reducing the risk of premature valve opening and pressure relief of the pressure relief mechanism, and is beneficial to improving the service life and reliability of the battery cell 20. On the other hand, the pressure relief mechanism made of steel or nickel material is relatively easy to weld with the wall portion made of steel material, which is beneficial to reducing the phenomenon of welding cracks between the pressure relief mechanism and the wall portion, thereby reducing the risk of liquid leakage of the battery cell 20 and improving the reliability of the battery cell 20.

[0163] Please refer to Figure 3 、 Figure 4 、 Figure 5 、 Figure 6 and Figure 7 , in some embodiments, the second direction is the width direction of the housing 21, and 10 mm ≤ L2 ≤ 100 mm.

[0164] The second direction is the width direction of the housing 21. At this time, L2 is the width of the housing 21.

[0165] The width of the housing 21 can be: L2 = 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, etc.

[0166] When 10 mm ≤ L2 ≤ 100 mm, the width of the housing 21 is of appropriate size, easy to manufacture, and has strong compatibility.

[0167] Please refer to Figure 5 、 Figure 6 、 Figure 7 、 Figure 8 and Figure 9 , Figure 8 is a top view schematic diagram of the battery cell 20 provided in some embodiments of the present application. Figure 9 is Figure 8Cross-sectional view taken along line B-B. In some embodiments, the side wall 2111 includes two first wall portions 21111 oppositely arranged along the second direction and two second wall portions 21112 oppositely arranged along the third direction. The first wall portion 21111 is the wall portion with the largest outer surface area of the outer shell 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 pairwise. 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%.

[0168] The second wall portion 21112 is the wall portion adjacent to the first wall portion 21111 in the side wall 2111. Generally speaking, the second wall portion 21112 is the wall portion with the smallest outer surface area of the outer shell 21, commonly known as the small surface. The two second wall portions 21112 are oppositely arranged along the third direction. Please refer to Figure 9 , 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 pairwise.

[0169] The third outer surface 21112a is the surface of the second wall portion 21112 facing away from the electrode assembly 22, and the third inner surface 21112b is the surface of the second wall portion 21112 facing the electrode assembly 22. Along the third direction, the third outer surface 21112a and the third inner surface 21112b are oppositely arranged.

[0170] The first outer surface 2111a includes the second outer surfaces 21111a of the two first wall portions 21111 and the third outer surfaces 21112a of the two second wall portions 21112, and the first inner surface 2111b includes the second inner surfaces 21111b of the two first wall portions 21111 and the third inner surfaces 21112b of the two second wall portions 21112.

[0171] L3 represents the distance along the third direction between the third inner surfaces 21112b of the two second wall portions 21112. When measuring, multiple measurements can be taken and the average value can be used as L3.

[0172] L4 represents the distance along the third direction between the third outer surfaces 21112a of the two second wall portions 21112. When measuring, multiple measurements can be taken and the average value can be used as L4.

[0173] L3 / L4 represents the ratio of the distance along the third direction between the third inner surfaces 21112b of the two second wall portions 21112 to the distance along the third direction between the third outer surfaces 21112a of the two second wall portions 21112.

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

[0175] 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 small, which is beneficial to increasing the internal space of the housing 211, enabling a larger electrode assembly 22 and more electrolyte to be accommodated inside the housing 211, thereby facilitating the improvement of 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, so that the second wall portion 21112 has sufficient structural strength, which is beneficial to 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.

[0176] Please refer to Figure 5 , Figure 6 , Figure 7 , Figure 8 and Figure 9 , in some embodiments, the thickness of the second wall portion 21112 is H2, satisfying: 0.05 mm ≤ H2 ≤ 0.4 mm.

[0177] H2 represents the thickness of the second wall portion 21112. During measurement, it can be measured multiple times and the average value can be taken as H2.

[0178] The thickness of the second wall portion 21112 can be: H2 = 0.05 mm, 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.22 mm, 0.25 mm, 0.28 mm, 0.3 mm, 0.32 mm, 0.35 mm, 0.38 mm, 0.4 mm, etc.

[0179] When H2 ≤ 0.4 mm, the thickness of the second wall portion 21112 is small, which is beneficial to increasing the internal space of the housing 211, enabling the housing 211 to accommodate a larger electrode assembly 22 and more electrolyte, thus facilitating the improvement of 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, such that the second wall portion 21112 has sufficient structural strength, which is beneficial to protecting the electrode assembly 22 and enhancing the reliability of the battery cell 20. Therefore, when 0.05 mm ≤ H2 ≤ 0.4 mm, the energy density and reliability of the battery cell 20 can be taken into account.

[0180] Please refer to Figure 5 、 Figure 6 、 Figure 7 、 Figure 8 and Figure 9 , in some embodiments, the third direction is the length direction of the outer shell 21, and 100 mm ≤ L4 ≤ 400 mm.

[0181] The third direction is the length direction of the outer shell 21. At this time, L4 is the length of the outer shell 21.

[0182] The length of the outer shell 21 can be: L4 = 100 mm, 120 mm, 150 mm, 180 mm, 200 mm, 220 mm, 250 mm, 280 mm, 300 mm, 320 mm, 350 mm, 380 mm, 400 mm, etc.

[0183] When 100 mm ≤ L4 ≤ 400 mm, the length of the outer shell 21 is of appropriate size, easy to manufacture, and has strong compatibility.

[0184] Please refer to Figure 5 、 Figure 6 、 Figure 7 、 Figure 8 and Figure 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 walls 2111 is connected to the bottom wall 2112, and the other end of the side walls 2111 encloses 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 L6 between the outer surface of the end cap 212 and the outer surface of the bottom wall 2112 satisfies: 98% ≤ L5 / L6 ≤ 99.7%.

[0185] Along the first direction, the bottom wall 2112 and the end cap 212 are oppositely arranged, and the bottom wall 2112 and the end cap 212 are respectively connected to both ends of the side walls 2111.

[0186] In some embodiments, the bottom wall 2112 and the side wall 2111 are integrally formed, that is, the housing 211 is manufactured by an integral forming process, such as stamping, casting, or extrusion molding and other integral forming processes. That is to say, the side wall 2111 and the bottom wall 2112 of the housing 211 are of an integral structure.

[0187] 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 finally connected together. For example, the bottom wall 2112 can be welded to the side wall 2111.

[0188] 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. When measuring, multiple measurements can be taken and the average value can be used as L5.

[0189] 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. When measuring, multiple measurements can be taken and the average value can be used as L6.

[0190] 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.

[0191] 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 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.

[0192] 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 thicknesses of the end cap 212 and the bottom wall 2112 are small, which is beneficial to increasing the internal space of the housing 211, enabling the housing 211 to accommodate a larger electrode assembly 22 and more electrolyte, and thus facilitating the improvement of the energy density of the battery cell 20. When L5 / L6 ≤ 99.7%, 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 not too large, and the thicknesses of the end cap 212 and the bottom wall 2112 are not too small, so that the end cap 212 and the bottom wall 2112 have sufficient structural strength, which is beneficial to protecting the electrode assembly 22 and improving the reliability of the battery cell 20. Therefore, when 98% ≤ L5 / L6 ≤ 99.7%, the energy density and reliability of the battery cell 20 can be balanced.

[0193] Please refer to Figure 5 、 Figure 6 、 Figure 7 、 Figure 8 and Figure 9 , in some embodiments, the thickness of the end cap 212 is H3, satisfying: 0.2 mm ≤ H3 ≤ 1.2 mm.

[0194] H3 represents the thickness of the end cap 212. During measurement, it can be measured multiple times and the average value can be taken as H3.

[0195] The thickness of the end cap 212 can be: H3 = 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, 0.95 mm, 1 mm, 1.05 mm, 1.1 mm, 1.15 mm, 1.2 mm, etc.

[0196] When H3 ≤ 1.2 mm, the thickness of the end cap 212 is small, which is beneficial to increasing the internal space of the housing 211, enabling the housing 211 to accommodate a larger electrode assembly 22 and more electrolyte, and thus facilitating the improvement of the energy density of the battery cell 20. When H3 ≥ 0.2 mm, the thickness of the end cap 212 is not too small, so that the end cap 212 has sufficient structural strength, which is beneficial to protecting the electrode assembly 22 and improving the reliability of the battery cell 20. Therefore, when 0.2 mm ≤ H3 ≤ 1.2 mm, the energy density and reliability of the battery cell 20 can be balanced.

[0197] Please refer to Figure 5 、 Figure 6 、Figure 7 , Figure 8 and Figure 9 , in some embodiments, the thickness of the bottom wall 2112 is H4, satisfying: 0.2 mm ≤ H4 ≤ 1 mm.

[0198] H4 represents the thickness of the bottom wall 2112. When measuring, it can be measured multiple times and the average value is taken as H4.

[0199] The thickness of the bottom wall 2112 can be: H4 = 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, 0.95 mm, 1 mm, etc.

[0200] When H4 ≤ 1 mm, the thickness of the bottom wall 2112 is relatively small, which is beneficial to increasing the internal space of the housing 211, so that a larger electrode assembly 22 and more electrolyte can be accommodated inside the housing 211, thereby being beneficial to 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, so that the bottom wall 2112 has sufficient structural strength, which is beneficial to protecting the electrode assembly 22 and improving the reliability of the battery cell 20. When 0.2 mm ≤ H4 ≤ 1 mm, the energy density and reliability of the battery cell 20 can be taken into account.

[0201] Please refer to Figure 5 , Figure 6 , Figure 7 , Figure 8 and Figure 9 , in some embodiments, the first direction is the height direction of the outer shell 21, 70 mm ≤ L6 ≤ 400 mm.

[0202] The first direction is the height direction of the outer shell 21. At this time, L6 is the height of the outer shell 21.

[0203] The height of the outer shell 21 can be: L6 = 70 mm, 80 mm, 90 mm, 100 mm, 120 mm, 150 mm, 180 mm, 200 mm, 220 mm, 250 mm, 280 mm, 300 mm, 320 mm, 350 mm, 380 mm, 400 mm, etc.

[0204] When 70 mm ≤ L6 ≤ 400 mm, the length of the outer shell 21 is of moderate size, easy to manufacture, and has strong compatibility.

[0205] Please refer to Figure 10 , Figure 11 , Figure 12 , Figure 13 and Figure 14 ,Figure 10 Schematic diagram of the battery cell 20 provided in some other embodiments of the present application. Figure 11 Explosion diagram of the battery cell 20 provided in some other embodiments of the present application. Figure 12 Top view schematic diagram of the housing 211 provided in some other embodiments of the present application. Figure 13 Top view schematic diagram of the battery cell 20 provided in some other embodiments of the present application. Figure 14 For Figure 13 Cross-sectional view at the C-C position in. In some other embodiments, the outer shell 21 is cylindrical, the inner diameter of the side wall 2111 is D1, and the outer diameter of the side wall 2111 is D2, satisfying: 97.7% ≤ D1 / D2 ≤ 99.9%.

[0206] Please refer to Figure 12 , when the outer shell 21 is a cylindrical structure, the first inner surface 2111b is the inner peripheral surface of the peripheral wall, and the first outer surface 2111a is the outer peripheral surface of the peripheral wall.

[0207] S1 is the area of the region defined by the projection of the first inner surface 2111b along the first direction. Please refer to Figure 12 , Figure 12 , in which S1 is marked with a mesh line. It should be noted that the mesh line here is only for facilitating the display of S1 and does not represent any physical meaning.

[0208] S2 is the area of the region defined by the projection of the first outer surface 2111a along the first direction, and S2 includes S1. Please refer to Figure 12 , Figure 12 , in which 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 marked with a cross-hatch. Among them, S2 = S1 + S3.

[0209] D1 represents the inner diameter of the side wall 2111, D2 represents the outer diameter of the side wall 2111, that is, the outer diameter of the outer shell 21. D1 / D2 represents the ratio of the inner diameter of the side wall 2111 to the outer diameter of the side wall 2111.

[0210] The ratio of the inner diameter of the side wall 2111 to the outer diameter of the side wall 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.

[0211] When D1 / D2 ≥ 97.7%, the ratio of the inner diameter to the outer diameter of the side wall 2111 is relatively large, indicating that the thickness of the side wall 2111 is relatively small, which is beneficial to increasing the internal space of the housing 211, enabling the housing 211 to accommodate a larger electrode assembly 22 and more electrolyte, and thus facilitating the improvement of 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 side wall 2111 is not overly large, and the thickness of the side wall 2111 is not overly small, such that the side wall 2111 has sufficient structural strength, which is beneficial to protecting the electrode assembly 22 and enhancing 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.

[0212] Please refer to Figure 10 、 Figure 11 、 Figure 12 、 Figure 13 and Figure 14 , in some embodiments, 10 mm ≤ D2 ≤ 400 mm.

[0213] D2 represents the outer diameter of the side wall 2111, that is, the outer diameter of the housing 21. The outer diameter of the housing 21 can be: D2 = 10 mm, 30 mm, 50 mm, 80 mm, 100 mm, 120 mm, 150 mm, 180 mm, 200 mm, 220 mm, 250 mm, 280 mm, 300 mm, 320 mm, 350 mm, 380 mm, 400 mm, etc.

[0214] When 10 mm ≤ D2 ≤ 400 mm, the outer diameter of the side wall 2111 is of a moderate size, which is easy to manufacture and has strong compatibility.

[0215] Please refer to again Figure 5 、 Figure 6 、 Figure 7 、 Figure 8 and Figure 9 , in some embodiments, the housing 21 is in the shape of a cuboid. The electrode assembly 22 includes a tab 222 and a main body 221, and the tab 222 protrudes 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 housing 21 is V, satisfying: 83.2% ≤ A·B·C / V ≤ 94.5%.

[0216] When the housing 21 is in the shape of a cuboid, the main body 221 is also approximately in the shape of a cuboid. Among them, A represents the length of the main body 221, B represents the width of the main body 221, C represents the height of the main body 221, and for the convenience of calculation, the volume of the main body 221 is represented by A·B·C.

[0217] Let V represent the volume of the housing 21, where V = L2·L4·L6.

[0218] A·B·C / V represents the ratio of the volume of the main body portion 221 to the volume of the housing 21.

[0219] The ratio of the volume of the main body portion 221 to the volume of the housing 21 can be: A·B·C / V = 83.2%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 94.5%, etc.

[0220] 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 housing 21, and the energy density of the battery cell 20 is relatively high. When A·B·C / V ≤ 94.5%, the proportion of the volume of the electrode assembly 22 in the volume of the housing 21 is not too large, so that there is a certain space in the housing 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, and the battery cell 20 can have a relatively high energy density.

[0221] Please refer to Figure 10 , Figure 11 , Figure 12 , Figure 13 and Figure 14 , in some other embodiments, the housing 21 is cylindrical. The electrode assembly 22 includes a tab 222 and a main body portion 221, and the tab 222 protrudes from the main body portion 221. The radius of the main body portion 221 is R, the height of the main body portion 221 in the first direction is H, the volume of the housing 21 is V, and it satisfies: 83.2% ≤ H·π·R 2 / V ≤ 94.5%.

[0222] When the housing 21 is cylindrical, the main body portion 221 is also substantially cylindrical. Among them, R represents the radius of the main body portion 221. Since the main body portion 221 has a central hole, R can also be understood as the outer diameter of the main body portion 221. H represents the height of the main body portion 221 in the first direction, and the volume of the main body portion 221 is represented by H·π·R 2 .

[0223] Let V represent the volume of the housing 21, where V = H·π·(D2 / 2) 2 .

[0224] H·π·R 2 / V represents the ratio of the volume of the main body portion 221 to the volume of the housing 21.

[0225] The ratio of the volume of the main body portion 221 to the volume of the housing 21 can be: H·π·R 2 / V = 83.2%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 94.5%, etc.

[0226] When H·π·R 2 / V ≥ 83.2%, the volume of the electrode assembly 22 accounts for a relatively large proportion of the volume of the housing 21, and the energy density of the battery cell 20 is relatively high. When H·π·R 2 / V ≤ 94.5%, the proportion of the volume of the electrode assembly 22 in the volume of the housing 21 is not too large, so that there is a certain space in the housing 21 to accommodate the electrolyte and other electrical connection components. Therefore, when 83.2% ≤ H·π·R 2 / V ≤ 94.5%, it is convenient to accommodate the electrolyte and other electrical connection components, and the battery cell 20 can have a relatively high energy density.

[0227] In some embodiments, the steel material is stainless steel.

[0228] Stainless steel is mainly characterized by being stainless and corrosion-resistant, with a chromium content of at least 10.5% and a maximum carbon content of no more than 1.2%. For example, 304 stainless steel, 305 stainless steel, 316 stainless steel, etc.

[0229] Stainless steel has the advantages of corrosion resistance, high temperature resistance, and good processing performance. The housing 211 made of stainless steel has relatively high strength. Under the condition of the same structural strength of the housing 211, the wall thickness of the housing 211 can be thinner. Moreover, the housing 211 made of stainless steel is not easily corroded, which is beneficial to improving the service life of the battery cell 20.

[0230] In some embodiments, the material of the end cap 212 is steel or titanium alloy.

[0231] The steel material can be carbon steel or stainless steel. The carbon steel can be low-carbon steel, medium-carbon steel, or high-carbon steel. The titanium alloy material refers to various alloy metals made of titanium and other metals. Titanium alloys have high strength, good corrosion resistance, and high heat resistance.

[0232] The steel material and the titanium alloy material have relatively high strength. Under the condition of the same structural strength of the end cap 212, the thickness of the end cap 212 made of steel or titanium alloy can be thinner, which is beneficial to increasing the internal space of the housing 21, so that a larger electrode assembly 22 and more electrolyte can be accommodated inside the housing 21. Under the same chemical material system, the volume energy density of the battery cell 20 can be improved.

[0233] The embodiment of the present application also provides a battery 100, and the battery 100 includes the above-mentioned battery cell 20.

[0234] Among them, seeFigure 2 As shown, the battery 100 may further include a box body 10, and the battery cells 20 are accommodated in the box body 10.

[0235] In some embodiments, the box body 10 may include a first part 11 and a second part 12. The first part 11 and the second part 12 cover each other, and the first part 11 and the second part 12 together define an assembly space for accommodating the battery cells 20.

[0236] Optionally, the second part 12 may be a hollow structure with one end open, and the first part 11 may 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; the first part 11 and the second part 12 may also 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.

[0237] Of course, the box body 10 formed by the first part 11 and the second part 12 may be of various shapes, such as a cylinder or a cuboid, etc. Exemplarily, in Figure 2 it, the box body 10 is of a cuboid structure.

[0238] Optionally, the number of battery cells 20 provided in the box body 10 may be one or more. Exemplarily, in Figure 2 it, a plurality of battery cells 20 are provided in the box body 10 of the battery 100. The plurality of battery cells 20 may be connected in series, in parallel, or in a series-parallel combination. A series-parallel combination means that there are both series and parallel connections among the plurality of battery cells 20. The plurality of battery cells 20 may be directly connected in series, in parallel, or in a series-parallel combination together, and then the whole formed by the plurality of battery cells 20 is accommodated in the box body 10; of course, the battery 100 may also be such that a plurality of battery cells 20 are first connected in series, in parallel, or in a series-parallel combination to form a battery module form, and then a plurality of battery modules are connected in series, in parallel, or in a series-parallel combination to form a whole and are accommodated in the box body 10.

[0239] Among them, the battery 100 may further include other structures. For example, the battery 100 may further include a busbar component, and the busbar component connects a plurality of battery cells 20 to realize the electrical connection among the plurality of battery cells 20.

[0240] It should be noted that in some embodiments, the battery 100 may not be provided with the box body 10. The battery 100 includes a plurality of battery cells 20, and the battery 100 composed of the plurality of battery cells 20 can be directly assembled to the electrical device to provide electrical energy for the electrical device through the plurality of battery cells 20. That is to say, the box body 10 can be used as a part of the electrical device. Taking the vehicle 1000 as an example of the electrical device, the box body 10 can be used as a part of the chassis structure of the vehicle 1000. For example, a part of the box body 10 can become at least a part of the floor of the vehicle 1000, or a part of the box body 10 can become at least a part of the cross beam and longitudinal beam of the vehicle 1000.

[0241] An embodiment of the present application also provides an electrical device, which includes the above-mentioned battery cell 20, and the battery cell 20 is used to provide electrical energy for the electrical device.

[0242] Among them, the electrical device can be any of the aforementioned devices or systems that apply the battery cell 20.

[0243] According to some embodiments of the present application, please refer to Figures 3 to 14 .

[0244] An embodiment of the present 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. At least one end of the shell 211 in the first direction has an opening, and the end cap 212 corresponds to the opening one by one, and the end cap 212 closes the opening. The electrode assembly 22 is accommodated in the housing 21. Among them, the material of the shell 211 is steel material or titanium alloy material. The shell 211 includes a side wall 2111 disposed around the electrode assembly 22, and the side wall 2111 has a first inner surface 2111b and a first outer surface 2111a. Along the first direction, the area of the region defined by the projection of the first inner surface 2111b is S1, and the area of the region defined by the projection of the first outer surface 2111a is S2, satisfying: 96.42% ≤ S1 / S2 ≤ 99.75%. The steel material and the titanium alloy material have higher strength. When the structural strength of the shell 211 is the same, the wall thickness of the shell 211 made of the steel material or the titanium alloy material can be thinner. When S1 / S2 ≥ 96.42%, the wall thickness of the side wall 2111 is thinner, the internal space of the shell 211 is larger, and a larger electrode assembly 22 and more electrolyte can be accommodated inside the shell 211. Under the same chemical material system, the volume energy density of the battery cell 20 can be improved. When S1 / S2 ≤ 99.75%, the wall thickness of the side wall 2111 is not too thin, so that the shell 211 has sufficient structural strength, thereby effectively protecting the electrode assembly 22 and improving the reliability of the battery cell 20. Therefore, when 96.42% ≤ S1 / S2 ≤ 99.75%, the energy density and reliability of the battery cell 20 can be taken into account.

[0245] Along the second direction, the side wall 2111 includes two relatively arranged first wall portions 21111, and at least one of the first wall portions 21111 is the wall portion with the largest outer surface area on the outer surface of the outer shell 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 small, which is beneficial to increasing the internal space of the housing 211, so that a larger electrode assembly 22 and more electrolyte can be accommodated inside the housing 211, thereby being beneficial to 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, so that the first wall portion 21111 has sufficient structural strength, which is beneficial to 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 taken into account.

[0246] The side wall 2111 includes two first wall portions 21111 oppositely arranged along the second direction and two second wall portions 21112 oppositely arranged along the third direction. The first wall portion 21111 is the wall portion with the largest outer surface area on the outer surface of the outer shell 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 pairwise. 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%. 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, which is beneficial to increasing the internal space of the housing 211, so that a larger electrode assembly 22 and more electrolyte can be accommodated inside the housing 211, thereby being beneficial to 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, so that the second wall portion 21112 has sufficient structural strength, which is beneficial to 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 taken into account.

[0247] The housing 211 includes a bottom wall 2112, and side walls 2111 surround the bottom wall 2112. One end of the side walls 2111 is connected to the bottom wall 2112, and the other end of the side walls 2111 encloses an opening. Along the first direction, the distance between the inner surface of the end cover 212 and the inner surface of the bottom wall 2112 is L5, and the distance between the outer surface of the end cover 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 cover 212 and the inner surface of the bottom wall 2112 to the distance between the outer surface of the end cover 212 and the outer surface of the bottom wall 2112 is relatively large, indicating that the thicknesses of the end cover 212 and the bottom wall 2112 are relatively small, which is beneficial to increasing the internal space of the housing 211, enabling a larger electrode assembly 22 and more electrolyte to be accommodated inside the housing 211, thereby being beneficial to improving the energy density of the battery cell 20. When L5 / L6 ≤ 99.7%, the ratio of the distance between the inner surface of the end cover 212 and the inner surface of the bottom wall 2112 to the distance between the outer surface of the end cover 212 and the outer surface of the bottom wall 2112 is not too large, and the thicknesses of the end cover 212 and the bottom wall 2112 are not too small, such that the thicknesses of the end cover 212 and the bottom wall 2112 have sufficient structural strength, which is beneficial to protecting the electrode assembly 22 and improving the reliability of the battery cell 20. Therefore, when 98% ≤ L5 / L6 ≤ 99.7%, the energy density and reliability of the battery cell 20 can be balanced.

[0248] In some embodiments, the outer shell 21 is in the shape of a cuboid. The electrode assembly 22 includes a tab 222 and a main body portion 221, and the tab 222 protrudes from the main body portion 221. The length of the main body portion 221 is A, the width of the main body portion 221 is B, the height of the main body portion 221 is C, and the volume of the outer shell 21 is V, satisfying: 83.2% ≤ A·B·C / V ≤ 94.5%. When A·B·C / V ≥ 83.2%, the proportion of the volume of the electrode assembly 22 in the volume of the outer shell 21 is relatively large, and the energy density of the battery cell 20 is relatively high. When A·B·C / V ≤ 94.5%, the proportion of the volume of the electrode assembly 22 in the volume of the outer shell 21 is not too large, such that there is a certain space inside the outer shell 21 to accommodate the electrolyte and other electrical connection components. Therefore, when 83.2% ≤ A·B·C / V ≤ 94.5%, it is both convenient to accommodate the electrolyte and other electrical connection components and enables the battery cell 20 to have a relatively high energy density.

[0249] In some other embodiments, the outer shell 21 is cylindrical. The inner diameter of the side wall 2111 is D1, and the outer diameter of the side wall 2111 is D2, satisfying 97.7% ≤ D1 / D2 ≤ 99.9%. When D1 / D2 ≥ 97.7%, the ratio of the inner diameter to the outer diameter of the side wall 2111 is relatively large, indicating that the thickness of the side wall 2111 is relatively small, which is beneficial to increasing the internal space of the housing 211, enabling the housing 211 to accommodate a larger electrode assembly 22 and more electrolyte, and thus facilitating the improvement of 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 side wall 2111 is not too large, and the thickness of the side wall 2111 is not too small, so that the side wall 2111 has sufficient structural strength, which is beneficial to protecting the electrode assembly 22 and improving 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 taken into account.

[0250] The outer shell 21 is cylindrical. The electrode assembly 22 includes a tab 222 and a main body 221, and the tab 222 protrudes from the main body 221. The radius of the main body 221 is R, the height of the main body 221 in the first direction is H, and the volume of the outer shell 21 is V, satisfying 83.2% ≤ H·π·R 2 / V ≤ 94.5%. When H·π·R 2 / V ≥ 83.2%, the volume ratio of the electrode assembly 22 to the volume of the outer shell 21 is relatively large, and the energy density of the battery cell 20 is relatively high. When H·π·R 2 / V ≤ 94.5%, the volume ratio of the electrode assembly 22 to the volume of the outer shell 21 is not too large, so that there is a certain space in the outer shell 21 to accommodate the electrolyte and other electrical connection components. Therefore, when 83.2% ≤ H·π·R 2 / V ≤ 94.5%, it is both convenient to accommodate the electrolyte and other electrical connection components and enables the battery cell 20 to have a relatively high energy density.

[0251] The materials of the housing 211 and the end cover 212 are both stainless steel. Stainless steel has the advantages of corrosion resistance, high temperature resistance, good processing performance, etc. The housing 211 made of stainless steel has relatively high strength, and the wall thickness of the housing 211 can be thinner under the same structural strength of the housing 211. Moreover, the housing 211 made of stainless steel is not easily corroded, which is beneficial to extending the service life of the battery cell 20.

[0252] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0253] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A battery cell, characterized in that, Comprising: A housing, including a housing body and an end cap, at least one end of the housing body in the first direction has an opening, the end cap corresponds to the opening one by one, and the end cap closes the opening; An electrode assembly, accommodated in the housing; Wherein, the material of the housing body is steel or titanium alloy, the housing body includes a side wall disposed around the electrode assembly, the side wall has a first inner surface and a first outer surface, along the first direction, the area of the region defined by the projection of the first inner surface is S1, and the area of the region defined by the projection of the first outer surface is S2, satisfying: 96.42% ≤ S1 / S2 ≤ 99.75%.

2. The battery cell according to claim 1, characterized in that, Along the second direction, the side wall includes 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 housing, and the second direction is 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%.

3. The battery cell according to claim 2, characterized in that, The thickness of the first wall portion is H1, satisfying: 0.05 mm ≤ H1 ≤ 0.3 mm.

4. The battery cell according to claim 2, wherein The second direction is the width direction of the housing, 10 mm ≤ L2 ≤ 100 mm.

5. The battery cell according to claim 1, characterized in that, The side wall includes two first wall portions arranged oppositely along the second direction and two second wall portions arranged oppositely along the third direction, the first wall portion is the wall portion with the largest outer surface area in the housing, 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 in pairs; Along 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, and the distance between the third outer surfaces of the two second wall portions is L4, satisfying: 99% ≤ L3 / L4 ≤ 99.95%.

6. The battery cell according to claim 5, wherein The thickness of the second wall portion is H2, satisfying: 0.05 mm ≤ H2 ≤ 0.4 mm.

7. The battery cell according to claim 5, wherein The third direction is the length direction of the housing, 100 mm ≤ L4 ≤ 400 mm.

8. The battery cell according to claim 1, characterized in that, The housing body includes a bottom wall, the side wall is disposed around the bottom wall, one end of the side wall is connected to the bottom wall, and the other end of the side wall encloses to form 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 L6 between the outer surface of the end cap and the outer surface of the bottom wall satisfies: 98% ≤ L5 / L6 ≤ 99.7%.

9. The battery cell according to claim 8, wherein, The thickness of the end cap is H3, satisfying: 0.2 mm ≤ H3 ≤ 1.2 mm.

10. The battery cell according to claim 8, wherein The thickness of the bottom wall is H4, satisfying: 0.2 mm ≤ H4 ≤ 1 mm.

11. The battery cell according to claim 8, wherein The first direction is the height direction of the housing, 70 mm ≤ L6 ≤ 400 mm.

12. The battery cell according to claim 1, wherein, The housing is cylindrical, the inner diameter of the side wall is D1, and the outer diameter of the side wall is D2, satisfying: 97.7% ≤ D1 / D2 ≤ 99.9%.

13. The battery cell according to claim 12, wherein 10 mm ≤ D2 ≤ 400 mm.

14. The battery cell according to any one of claims 1-11, characterized in that, The outer shell is in the shape of a cuboid. The electrode assembly includes a tab and a main body portion, and the tab protrudes from the main body portion. The length of the main body portion is A, the width of the main body portion is B, the height of the main body portion is C, and the volume of the outer shell is V, satisfying: 83.2% ≤ A·B·C / V ≤ 94.5%.

15. The battery cell according to claim 1, 12 or 13, characterized in that, The outer shell is in the shape of a cylinder. The electrode assembly includes a tab and a main body portion, and the tab protrudes from the main body portion. 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%.

16. The battery cell according to any one of claims 1-11, characterized in that, The steel material is stainless steel.

17. The battery cell according to any one of claims 1-11, characterized in that, The material of the end cover is steel material or titanium alloy material.

18. A battery, characterized in that, It includes a battery cell according to any one of claims 1-17.

19. An electrical device, characterized in that, It includes a battery cell according to any one of claims 1-17, and the battery cell is used to provide electrical energy for the electrical equipment.

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