Battery cell, battery, and electrical device

Abstract

A battery cell (20), a battery (100), and an electrical device. The battery cell (20) comprises a casing, an electrode assembly (23), and a venting assembly (90). The casing has a wall portion and an accommodating cavity (221). The venting assembly (90) is arranged on the wall portion. The electrode assembly (23) comprises a negative electrode sheet. The negative electrode sheet comprises a negative electrode current collector and a carbon-containing coating arranged on one side surface of the negative electrode current collector. The thickness of the carbon-containing coating is: 1 μm≤L≤15 μm. By equipping the battery cell with the venting assembly (90) having a venting function, the conflict between the high-performance requirement for the battery cell (20) and the excessive gas generation can be balanced, and the impact of external moisture ingress on the battery cell (20) in a venting process is reduced.

Description

Battery cells, batteries and electrical equipment

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202410269570.4, filed on March 8, 2023, entitled “Battery Cell, Battery and Electrical Equipment,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of new energy technology, and in particular to a battery cell, a battery, and an electrical device. Background Art

[0004] As global energy and environmental issues continue to intensify, new energy sources, as a key area of ​​sustainable development, are rapidly developing. Batteries, as a new energy source, are becoming increasingly widespread, placing high demands on their safety and service life. During the charge and discharge process, gases generated within the battery cells can increase the internal pressure, reducing their safety and shortening their service life. The foregoing statements are intended only to provide background information related to this application and do not necessarily constitute prior art. Summary of the Invention

[0005] The main technical problem solved by this application is to provide a battery cell, a battery and an electrical device, which can discharge the internal gas of the battery cell to the outside of the battery cell shell in time, so that the gas pressure inside the battery cell is maintained at a normal level, which can improve the safety performance of the battery and greatly increase the battery life.

[0006] To solve the above problems, the present application adopts a technical solution: providing a battery cell, the battery cell comprising a housing, an exhaust assembly, and an electrode assembly, the housing having a wall portion and a receiving cavity; the exhaust assembly being disposed on the wall portion and used to exhaust the gas inside the housing; the electrode assembly being accommodated in the receiving cavity, the electrode assembly comprising a negative electrode plate, the negative electrode plate comprising a negative electrode current collector and a carbonaceous coating disposed on one surface of the negative electrode current collector, the thickness of the carbonaceous coating being 1μm≤L≤15μm. Through this arrangement, the battery cell can be equipped with an exhaust assembly having an exhaust function, which can balance the contradiction between the high performance requirements and high gas production of the battery cell, while reducing the impact of external water vapor intrusion on the battery cell during the exhaust process.

[0007] In one embodiment, the thickness of the carbon-containing coating is 1 μm≤L≤8 μm. This configuration can reduce the gas generation of the battery cell.

[0008] In one embodiment, the carbon content of the carbon-containing coating is 5%-50% based on the total mass of the carbon-containing coating. This configuration can reduce the gas production of the battery cell.

[0009] In one embodiment, the water content of the negative electrode plate is 100 ppm to 600 ppm. This configuration can reduce the gas production of the battery cell.

[0010] In one embodiment, the electrode assembly further includes a positive electrode sheet, which includes a positive electrode active material. The residual alkali content of the positive electrode active material is 0% wt < 0.5% wt, based on the total weight of the positive electrode active material. The residual alkali includes one or more of oxides, hydroxides, carbonates, and nitrates of active ions. This configuration can reduce gas generation in the battery cells.

[0011] In one embodiment, the electrode assembly further comprises a positive electrode sheet, the positive electrode sheet comprises a positive electrode active material, and the specific surface area of ​​the positive electrode active material is 2m 2 / g<Specific surface area≤7m 2 This configuration can reduce the gas production of the battery cells.

[0012] In one embodiment, the electrode assembly further includes a positive electrode sheet, which includes a positive electrode active material. The carbon content of the positive electrode active material is 0.5% < carbon content ≤ 1.5% based on the total mass of the positive electrode active material. This configuration can reduce gas generation in the battery cell.

[0013] In one embodiment, the electrode assembly further comprises a positive electrode sheet, and the water content of the positive electrode sheet is 50 ppm to 400 ppm, which can reduce the gas generation of the battery cell.

[0014] In one embodiment, the battery cell further comprises an electrolyte, the electrolyte is filled in the receiving cavity, and the conductivity of the electrolyte is 0.5 ms / cm≤conductivity≤5 ms / cm. This configuration can reduce the gas generation of the battery cell.

[0015] In one embodiment, the exhaust assembly includes a breathable membrane assembly, which includes a breathable membrane with a permeability rate of 2.0-10.0 mL / day. This arrangement allows for timely exhaust of gases within the battery cell while preventing external impurities (air, moisture, dust, etc.) from entering the battery cell.

[0016] In one embodiment, the breathable membrane has a thickness of 20 μm ≤ 100 μm. This configuration balances the strength, air permeability, and water permeability of the breathable membrane, resulting in a higher strength of the breathable membrane, a lower probability of deformation and damage, and improved water vapor barrier capability while meeting ventilation requirements.

[0017] In one embodiment, the permeable area of ​​the breathable membrane accounts for 5%-10% of the area of ​​the wall where the breathable membrane assembly is located. This arrangement can reduce the intrusion of external water vapor into the battery cells while meeting the ventilation requirements.

[0018] In one embodiment, the vent assembly includes a breathable membrane assembly and a one-way valve. The wall portion has a first vent hole, which connects the interior and exterior of the housing. The battery cells are configured so that gas exhausted through the first vent hole flows through the one-way valve and the breathable membrane assembly. In this solution, the breathable membrane assembly and the one-way valve are arranged in series. The one-way valve protects the sealing of the battery cell system and reduces the probability of external moisture entering the battery cell system. Furthermore, the breathable membrane prevents electrolyte leakage and seals the battery cell system when the one-way valve is open.

[0019] In one embodiment, the opening pressure of the one-way valve is greater than or equal to 0.4 MPa. By adjusting the valve opening pressure, it is possible to adapt to different application scenarios and different exhaust requirements.

[0020] In one embodiment, the exhaust assembly includes a breathable membrane assembly and a one-way valve. The wall portion has first and second exhaust holes spaced apart, connecting the interior and exterior of the housing, respectively. The battery cells are configured so that gas exhausted through the first exhaust hole flows through the one-way valve, while gas exhausted through the second exhaust hole flows through the breathable membrane assembly. In this solution, the breathable membrane assembly and the one-way valve are arranged in parallel, allowing them to exhaust gas simultaneously, achieving a relatively high exhaust rate.

[0021] In one embodiment, the opening pressure of the one-way valve is greater than or equal to 0.5 MPa. By adjusting the opening pressure of the valve, it is possible to adapt to different application scenarios and different exhaust requirements.

[0022] In one embodiment, the thickness of the carbon-containing coating is 8 μm<L≤15 μm. With this configuration, the gas generation of the battery cell can be controlled while enhancing the battery performance.

[0023] In one embodiment, the carbon content of the carbon-containing coating is 50%-90% based on the total mass of the carbon-containing coating. With this configuration, the gas production of the battery cell can be controlled while enhancing battery performance.

[0024] In one embodiment, the water content of the negative electrode plate is 600 ppm to 1200 ppm. This configuration can enhance battery performance while controlling the gas production of the battery cells.

[0025] In one embodiment, the electrode assembly further includes a positive electrode sheet, which includes a positive electrode active material. The residual alkali content of the positive electrode active material is 0.5%wt < 1.5%wt based on the total mass of the positive electrode active material. The residual alkali includes one or more of oxides, hydroxides, carbonates, and nitrates of active ions. This configuration enhances battery performance while controlling the gas production of the battery cells.

[0026] In one embodiment, the electrode assembly further comprises a positive electrode sheet, the positive electrode sheet comprises a positive electrode active material, and the specific surface area of ​​the positive electrode active material is 7m 2 / g<Specific surface area≤15m 2 This configuration can enhance battery performance while controlling the gas production of the battery cells.

[0027] In one embodiment, the electrode assembly further includes a positive electrode sheet, which includes a positive electrode active material. The carbon content of the positive electrode active material is 1.5% < carbon content ≤ 2.5% based on the total mass of the positive electrode active material. This configuration can enhance battery performance while controlling the gas production of the battery cells.

[0028] In one embodiment, the electrode assembly further comprises a positive electrode sheet, and the water content of the positive electrode sheet is 400 ppm to 1000 ppm, thereby enhancing battery performance while controlling the gas production of the battery cell.

[0029] In one embodiment, the battery cell further comprises an electrolyte, the electrolyte filling the receiving cavity, and the conductivity of the electrolyte is 5ms / cm≤conductivity≤15ms / cm. This configuration can enhance battery performance while controlling the gas production of the battery cell.

[0030] In one embodiment, the electrolyte includes a first component, wherein the first component includes one or a mixture of two or more of dimethyl carbonate, 2-methyltetrahydrofuran, diethylene glycol dimethyl ether, diethylene glycol dimethyl ether, succinonitrile, glutaronitrile, methyl formate, ethyl formate, methyl acetate, ethyl acetate, methyl acrylate, dimethyl sulfite, diethyl sulfite, methyl ethyl sulfite, 3-methyl-2-butanone, and 3-methyl-2-butanone. This configuration balances the conflict between high battery performance requirements and high gas production, improving the battery cell's charging capacity and energy density while also taking into account the safety performance and service life of the battery cell.

[0031] In one embodiment, the content of the first component is 5%-85% based on the total mass of the electrolyte. By adjusting the electrolyte content of different components, the contradiction between high performance requirements and high gas production can be balanced.

[0032] In one embodiment, the exhaust assembly includes a one-way valve with an opening pressure of 0.3 MPa-0.5 MPa. With this configuration, exhausting the battery using the one-way valve is essentially intermittent exhaust, shortening the exhaust time of the battery cell and improving the sealing of the battery cell.

[0033] In one embodiment, the vent assembly includes a one-way valve and a breathable membrane assembly. The wall portion has a first vent hole, which connects the interior and exterior of the housing. The battery cells are configured so that gas exhausted through the first vent hole flows through the one-way valve and the breathable membrane assembly. In this solution, the breathable membrane assembly and the one-way valve are arranged in series. The one-way valve protects the sealing of the battery cell system and reduces the probability of external moisture entering the battery cell system. The breathable membrane also prevents electrolyte leakage and seals the battery cell system when the one-way valve is open.

[0034] In one embodiment, the exhaust assembly includes a one-way valve and a breathable membrane assembly. The wall portion has first and second vent holes spaced apart, connecting the interior and exterior of the housing, respectively. The battery cells are configured so that gas exhausted through the first vent hole flows through the one-way valve, while gas exhausted through the second vent hole flows through the breathable membrane assembly. In this solution, the breathable membrane assembly and the one-way valve are arranged in parallel, allowing them to exhaust gas simultaneously, achieving a relatively high exhaust rate.

[0035] In one embodiment, the air permeability of the breathable membrane satisfies the requirement of being greater than 0 and less than or equal to 15 mL / D, and the water permeability satisfies the requirement of being 10 -4 MPa. This setting can timely discharge the gas inside the battery cell and prevent external impurities (air, moisture, dust, etc.) from entering the battery cell.

[0036] In one embodiment, the electrode assembly includes a positive electrode plate, which includes a positive electrode active material. The positive electrode active material includes a first type of material, which includes a first ternary material. The nickel content of the first ternary material is 50% by weight ≤ 100%. This configuration can achieve a higher gram capacity, thereby increasing the energy density of the battery cell.

[0037] In one embodiment, the median particle size Dv50 of the first ternary material is 2-4 μm. This configuration can reduce the contact area between the ternary material and the electrolyte, thereby reducing gas generation.

[0038] In one embodiment, the mass content of cobalt in the first ternary material is 12%-18%. By adjusting the mass content of cobalt, the stability of the positive electrode active material can be improved.

[0039] In one embodiment, based on the total mass of the positive electrode active material, the content of the first ternary material is greater than or equal to 50%. By controlling the content of the first ternary material, the cost of the positive electrode material can be reduced while increasing the energy density.

[0040] In one embodiment, the first ternary material includes one or more of single crystal particles and polycrystalline particles. This configuration can increase capacity and reduce gas production.

[0041] In one embodiment, the battery cells include alkali metal battery cells.

[0042] In one embodiment, the carbon-containing coating comprises a carbon-containing material, wherein the carbon-containing material comprises one or more of conductive carbon, graphite, hard carbon, and carbon nanotubes. This configuration facilitates more uniform deposition of the negative electrode metal and reduces gas production.

[0043] In one embodiment, the wall portion has an outer surface and an inner surface disposed in opposite directions, the outer surface facing the exterior of the housing and the inner surface facing the interior of the housing. The first vent includes a through-hole segment and a first hole segment, the through-hole segment and the first hole segment being arranged along the thickness of the wall portion. The first hole segment is located on a side of the through-hole segment facing away from the interior of the housing. The aperture of the first hole segment is larger than the aperture of the through-hole segment. The one-way valve covers the first vent. This arrangement facilitates assembly of the one-way valve.

[0044] In one embodiment, at least a portion of the one-way valve body protrudes from the outer surface; the wall portion includes a first recessed portion that is recessed relative to the inner surface. The first recessed portion surrounds the through-hole section of the first vent hole, and the breathable membrane assembly is at least partially accommodated within the first recessed portion. This arrangement can reduce the installation height of the vent assembly.

[0045] In one embodiment, at least a portion of the one-way valve body protrudes from the outer surface; the first vent further includes a second hole segment, located between the through-hole segment and the first hole segment along the thickness of the wall portion, with the second hole segment having a smaller aperture than the first hole segment and a larger aperture than the through-hole segment. The breathable membrane assembly is at least partially accommodated within the second hole segment, and is located on the side of the one-way valve facing the wall portion. This arrangement facilitates assembly of the vent assembly.

[0046] In one embodiment, a one-way valve includes a valve body, at least a portion of which protrudes from the inner surface of the wall portion. The valve body includes a valve seat and a valve cover. The valve seat includes a seat bottom wall and a seat sidewall connected to the seat bottom wall. The valve cover is disposed at an end of the valve seat away from the seat bottom wall. The valve cover, the seat sidewall, and the seat bottom wall enclose a valve cavity. The valve seat is provided with an air inlet for the valve cavity. The breathable membrane assembly is disposed on a side of the seat bottom wall away from the valve cavity, or on a side of the seat bottom wall facing the valve cavity. This arrangement can reduce the installation height of the exhaust assembly.

[0047] In one embodiment, a one-way valve includes a valve body and a valve core. The valve body defines a valve cavity. The valve body is provided with an air inlet and an air outlet. The air inlet connects the valve cavity with the interior of the housing, while the air outlet connects the valve cavity with the exterior of the housing. The valve core is disposed within the valve cavity and blocks the air inlet passage of the valve cavity. The valve core is configured to open the air inlet passage in response to gas within the housing. This arrangement facilitates the discharge of gas.

[0048] In one embodiment, the breathable membrane assembly includes a breathable membrane and a connector. The connector is provided with a first breathable hole. The breathable membrane is disposed on the connector and covers the first breathable hole. The breathable membrane is configured to allow gas within the battery cell to pass through the breathable membrane and escape. This arrangement improves the connection strength of the breathable membrane assembly and reduces the risk of deformation of the breathable membrane.

[0049] To solve the above technical problems, another technical solution adopted by the present application is to provide an electrical device comprising the above battery, which has at least the same advantages as the battery.

[0050] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0052] FIG1 is a schematic diagram of an exploded structure of a battery cell according to one or more embodiments;

[0053] FIG2 is a schematic diagram of an exploded structure of a battery cell according to one or more embodiments;

[0054] FIG3 is a schematic cross-sectional view of a one-way valve according to one or more embodiments;

[0055] FIG4 is a schematic diagram of a partially exploded structure of a battery cell according to one or more embodiments;

[0056] FIG5 is a front schematic view of a one-way valve according to one or more embodiments;

[0057] FIG6 is a schematic diagram of an exploded structure of a one-way valve according to one or more embodiments;

[0058] FIG7 is a schematic diagram of a partial cross-sectional structure of a battery cell according to one or more embodiments;

[0059] FIG8 is a front view of a one-way valve according to one or more embodiments;

[0060] FIG9 is a schematic diagram of an exploded structure of a one-way valve according to one or more embodiments;

[0061] FIG10 is a schematic diagram of a partial cross-sectional structure of a battery cell according to one or more embodiments;

[0062] FIG11 is a schematic cross-sectional view of a breathable membrane assembly according to one or more embodiments;

[0063] FIG12 is a schematic diagram of a partial cross-sectional structure of an end cap according to one or more embodiments;

[0064] FIG13 is a schematic diagram of a partial cross-sectional structure of a battery cell according to one or more embodiments;

[0065] FIG14 is a partial front view of a battery cell according to one or more embodiments;

[0066] FIG15 is a schematic diagram of a partial cross-sectional structure of an end cap according to one or more embodiments;

[0067] FIG16 is a schematic diagram of a partial cross-sectional structure of a battery cell according to one or more embodiments;

[0068] FIG17 is a partial front view of a battery cell according to one or more embodiments;

[0069] FIG18 is an exploded view of an exhaust assembly according to one or more embodiments;

[0070] FIG19 is a schematic cross-sectional view of an exhaust assembly according to one or more embodiments.

[0071] FIG20 is an exploded structural diagram of an exhaust assembly according to one or more embodiments;

[0072] FIG21 is a schematic cross-sectional view of an exhaust assembly according to one or more embodiments;

[0073] FIG22 is an exploded view of an exhaust assembly according to one or more embodiments;

[0074] FIG23 is a schematic cross-sectional view of an exhaust assembly according to one or more embodiments.

[0075] FIG24 is a schematic diagram of an exploded structure of a battery according to one or more embodiments;

[0076] FIG25 is a schematic structural diagram of a vehicle according to one or more embodiments.

[0077] In the attached figure:

[0078] 1000, vehicle; 300, motor; 200, controller; 100, battery; 10, housing; 11, first portion; 12, second portion; 20, battery cell; 21, end cap; 21a, outer surface; 21b, inner surface; 291, first vent; 22, housing; 221, accommodating chamber; 23, electrode assembly; 24, insulator; 293, second vent; 25, electrode terminal; 90, vent assembly; 30, one-way valve; 31, valve body; 311, valve seat; 3111, first through hole; 3114, fourth through hole; 3115, seat bottom wall; 3116 , seat side wall; 312, valve cover; 3121, cover top wall; 3122, cover side wall; 31221, second through hole; 3123, fifth through hole; 313, valve cavity; 313a, air inlet; 313b, air outlet; 32, valve core; 321, blocking member; 3211, sealing part; 3212, pressing part; 322, elastic member; 40, breathable membrane assembly; 41, breathable membrane; 42, metal member; 491, first air hole; 43, backing member; 70, pressure relief mechanism; T1, first annular table; T2, second annular table; T3, transition surface; S1, first sinking platform. DETAILED DESCRIPTION

[0079] In order to make the purpose, technical solution and effect of this application clearer and more specific, the following embodiments of the technical solution of this application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of this application and are therefore only examples and are not intended to limit the scope of protection of this application.

[0080] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0081] In the description of the embodiments of the present application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two), similarly, "multiple groups" refers to more than two (including two), and "multiple pieces" refers to more than two (including two), unless otherwise clearly and specifically defined.

[0082] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0083] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0084] Amounts, ratios, and other numerical values ​​are presented herein in a range format. It should be understood that such range format is used for convenience and brevity and should be interpreted flexibly to include not only the values ​​explicitly specified as range limits, but also all individual values ​​or sub-ranges encompassed within the range, as if each value and sub-range were explicitly specified.

[0085] In the description of the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and do not constitute any limitation on this application.

[0086] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0087] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0088] Batteries have a wide range of applications in the new energy sector, primarily in electric vehicles, energy storage systems, and renewable energy. In the electric vehicle sector, higher performance features such as longer driving range and faster charging are gradually being achieved. In energy storage systems, batteries are widely used for large-scale and distributed energy storage. They can balance grid loads, store renewable energy such as solar and wind power, and release the stored energy during peak periods. Furthermore, small rechargeable batteries are widely used in applications such as wearable devices, drones, and smart homes.

[0089] Please refer to Figure 1, which shows an exploded view of a battery cell according to one or more embodiments. A battery cell 20 is the smallest unit of a battery. As shown in Figure 1, a battery cell 20 includes an end cap 21, a housing 22, an electrode assembly 23, and other functional components.

[0090] The end cap 21 refers to a component that covers the opening of the housing 22 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cap 21 can be adapted to the shape of the housing 22 to match the housing 22. In one embodiment, the end cap 21 can be made of a material with a certain hardness and strength (such as an aluminum alloy). In this way, the end cap 21 is less likely to deform when squeezed or collided, so that the battery cell 20 can have a higher structural strength and improved safety performance. Functional components such as electrode terminals 25 can be provided on the end cap 21. The electrode terminals 25 can be used to electrically connect to the electrode assembly 23 to output or input electrical energy from the battery cell 20. Exemplarily, the battery cell 20 is provided with two electrode terminals 25, and both electrode terminals 25 are mounted on the end cap 21. The two electrode terminals 25 are respectively used to electrically connect to the two tabs of the electrode assembly 23 with opposite polarity to respectively output or input the positive and negative electrodes of the battery cell 20. In some embodiments, the end cap 21 may also be provided with a pressure relief mechanism 70 for relieving internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The end cap 21 may be made of a variety of materials, including but not limited to copper, iron, aluminum, stainless steel, aluminum alloy, plastic, and the like. In some embodiments, an insulating member 24 may be provided inside the end cap 21 to isolate the electrical connection components within the housing 22 from the end cap 21, thereby reducing the risk of short circuits. Exemplary insulating members may be made of plastic, rubber, and the like.

[0091] The housing 22 is a component that cooperates with the end cap 21 to form the internal environment of the battery cell 20, wherein the formed internal environment can be used to accommodate the electrode assembly 23, electrolyte, and other components. The housing 22 and the end cap 21 can be independent components. An opening can be provided in the housing 22, and the end cap 21 is closed at the opening to form the internal environment of the battery cell 20. The end cap 21 and the housing 22 can also be integrated. Specifically, the end cap 21 and the housing 22 can form a common connection surface before other components are inserted into the housing. When the interior of the housing 22 needs to be encapsulated, the end cap 21 is closed to the housing 22. The housing 22 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the housing 22 can be determined according to the specific shape and size of the electrode assembly 23. The housing 22 can be made of various materials, including but not limited to copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0092] The electrode assembly 23 is a component in the battery cell 20 where electrochemical reactions occur. One or more electrode assemblies 23 may be contained in the housing 22. The electrode assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and a separator is usually provided between the positive and negative electrode sheets. The parts of the positive and negative electrode sheets with active materials constitute the main body of the electrode assembly, and the parts of the positive and negative electrode sheets without active materials each constitute a tab. The positive and negative electrode tabs may be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery, the positive active material and the negative active material react with the electrolyte, and the tabs connect the electrode terminals to form a current loop.

[0093] In one embodiment, the positive electrode sheet includes a positive electrode current collector and a positive electrode active layer disposed on at least one side of the positive electrode current collector, wherein the positive electrode active layer includes a positive electrode active material.

[0094] As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode active layer may be disposed on either or both of the two opposite surfaces of the positive electrode current collector.

[0095] In one embodiment, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0096] In one embodiment, the positive electrode material includes one or more of a polyanion positive electrode material, a phosphate positive electrode material, a sulfate positive electrode material, a silicate positive electrode material, and a borate positive electrode material. For example, in the positive electrode active material of a sodium battery, the polyanion compound includes a compound based on phosphoric acid and fluorophosphate. The compound based on phosphoric acid includes Na x1 Fe y1 P m1 O n1 For example, sodium iron phosphate with a higher capacity and sodium iron pyrophosphate with a higher voltage platform. Polyanionic compounds include sodium vanadium trifluorophosphate Na3V2(PO4)2F3, sodium vanadium fluorophosphate NaVPO4F, sodium vanadium phosphate Na3V2(PO4)3, Na4Fe3(PO4)2P2O7, NaFePO4, Na3V2(PO4)3. Prussian blue compounds are Na xMM(CN)6, where M and M are one or more of Fe, Mn, Co, Ni, Cu, Zn, Cr, Ti, V, Zr, and Ce, and 0 < x ≤ 2. The positive electrode active material in the lithium metal battery may include at least one of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, or lithium iron manganese phosphate.

[0097] In one embodiment, the positive electrode active layer may further include a binder and a conductive agent. As an example, the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and at least one of a fluorine-containing acrylate resin. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0098] In one embodiment, the negative electrode sheet includes a negative electrode current collector and a carbonaceous coating disposed on at least one surface of the negative electrode current collector.

[0099] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the carbon-containing coating may be provided on either or both of the two opposite surfaces of the negative electrode current collector.

[0100] In one embodiment, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base material. The composite current collector may be obtained by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0101] In one embodiment, the battery cell is a metal battery, and during the charge and discharge process of the battery, active ions are deposited / stripped at the negative electrode. The metal battery can be an alkali metal battery, such as a lithium metal battery, a sodium metal battery, a potassium metal battery, a zinc metal battery, or an aluminum metal battery. This type of battery can also be called a "negative electrode-free battery". The so-called "negative electrode-free" means that no negative electrode active material is provided. During the charging process, the active ions (such as Na) released from the positive electrode active material are used to generate the negative electrode active material. + ) is deposited onto the negative electrode current collector to form sodium metal. The provision of a carbon-containing coating facilitates more uniform metal deposition.

[0102] In some embodiments, the carbon-containing material includes one or more of conductive carbon, graphite, hard carbon, and carbon nanotubes, which facilitates more uniform metal deposition.

[0103] In other embodiments, a conductive film layer may be deposited on the negative electrode current collector. Examples include alloy materials, titanium-based materials, active metals (e.g., sodium metal), carbon-based materials deposited with metals, composite materials containing metals, and alloy materials containing metals. Such alloy materials include, but are not limited to, sodium-tin alloys, sodium-germanium alloys, and sodium-antimony alloys. Such titanium-based materials include, but are not limited to, titanium dioxide, titanates, and titanium phosphates.

[0104] In one embodiment, the isolation membrane can be any known porous structure isolation membrane with good chemical stability and mechanical stability.

[0105] In one embodiment, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0106] The electrolyte conducts ions between the positive and negative electrodes. The electrolyte can be liquid, gel, or solid.

[0107] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent. The electrolyte salt dissolves to form electrolyte ions, and conduction is achieved through the movement of the electrolyte ions in the electrolyte salt.

[0108] In one embodiment, in a sodium battery, the electrolyte salt includes sodium hexafluorophosphate (NaPF6), sodium bis(fluorosulfonyl)imide (NaFSI), sodium trifluoromethanesulfonate (CF3NaO3S), sodium sulfide (Na2S), and the like. A lithium battery includes at least one lithium salt selected from the group consisting of lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluorophosphate, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium difluorooxalatoborate, lithium tetrafluoroborate, and lithium trifluoromethanesulfonate.

[0109] In one embodiment, the solvent includes one or more solvents selected from the group consisting of chain ethers, ethylene glycol dimethyl ether and its derivatives, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and cyclic ethers, specifically including dimethyl ether (DME), diethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, 2,2,2,2-trifluoroethyl ether, ethylene glycol diethyl ether, triethylene glycol dimethyl ether, ethylene glycol dimethyl ether derivatives, trifluoroethyl methyl carbonate (FEMC), dioxolane (DOL), acetonitrile (AN), fluorobenzene, triethyl phosphate (TEP), sulfolane, 2-methyltetrahydrofuran, tetrahydrofuran, dimethyl sulfoxide, N,N-dimethylacetamide, and the like.

[0110] In one embodiment, the electrolyte may further include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives capable of improving certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0111] During the charge and discharge process of battery cells, some side reactions generate gases. If the gases generated inside the battery cells are not discharged in a timely manner, the internal pressure of the battery cells will increase. Excessive internal pressure will have a negative impact on the performance and appearance of the battery cells. For example, in severe cases, it will have a destructive impact on the performance and appearance of the battery cells, such as leakage, bulging, increased internal resistance of the battery cells, and shortened discharge time and cycle life. In addition, there are some abnormal operations of battery cells during use, including overcharging, over-discharging, and internal failures. In this case, the chemical reaction inside the battery cells may be uncontrolled, accompanied by a violent release of gas, and even cause thermal runaway of the battery cells. Thermal runaway of battery cells refers to a chain reaction phenomenon triggered by various factors. The large amount of heat and harmful gases emitted by thermal runaway can cause the battery cells to catch fire and explode.

[0112] Common alkali metal batteries (including but not limited to lithium metal batteries, sodium metal batteries, potassium metal batteries, zinc metal batteries, and aluminum metal batteries) show very obvious differences in gas production patterns (including gas production volume, gas composition, and gas production rate) compared to secondary alkali ion batteries during long-term charging and discharging. Specifically, during the cycle and storage of battery cells, the gas production inside the battery cells of alkali metal batteries accumulates rapidly in a short period of time, compressing the residual space inside the battery cells, and even worse, it cannot be released, thereby directly triggering the opening of the pressure relief mechanism. At the same time, the gas production of alkali metal batteries is often accompanied by a large amount of active gases such as hydrogen (H2), methane (CH4), ethane (C2H6), and oxygen (O2). This part of the gas needs to be discharged in time at the appropriate time. Therefore, the safety protection of the battery cells is achieved by cooperating with the exhaust components provided in the battery cells.

[0113] Please refer to Figure 2, which is a schematic diagram of the exploded structure of a battery cell according to one or more embodiments. According to some embodiments of the present application, the present application discloses a battery cell 20, which includes a housing and a vent assembly 90. The housing has a wall portion and a receiving cavity 221. The vent assembly 90 is disposed on the wall portion and is used to exhaust gas from the interior of the housing. The provision of the vent assembly 90 can promptly exhaust gas from the interior of the battery cell housing to the exterior of the housing, maintaining the air pressure within the battery cell housing within a normal level, thereby improving the safety performance of the battery cell and significantly extending the life of the battery cell.

[0114] In this embodiment, the battery cell 20 also includes an electrode assembly 23, which is accommodated in the accommodating cavity 221. The electrode assembly 23 includes a negative electrode plate, which includes a negative electrode collector and a carbon-containing coating arranged on one side surface of the negative electrode collector. The thickness of the carbon-containing coating is 1μm≤L≤15μm.

[0115] The negative electrode current collector has two surfaces facing each other in its thickness direction, and the carbon-containing coating can be provided on either or both of the two facing surfaces of the negative electrode current collector. The thickness of the carbon-containing coating refers to the thickness of the carbon-containing coating on a single surface.

[0116] In alkali metal battery cells, active ions are deposited / stripped at the negative electrode during the battery charge and discharge process. For example, in sodium batteries, on the negative electrode side, Na + The carbon coating helps ensure uniform metal deposition. However, uneven metal deposition can easily lead to side reactions, which can worsen the gassing behavior of the battery cells and cause excessive gassing.

[0117] In this embodiment, the thickness of the carbon-containing coating is 1μm ≤ L ≤ 15μm. For example, it can be 1μm, 3μm, 5μm, 8μm, 10μm, 12μm, 15μm, etc. The thickness of the carbon-containing coating will affect the gas production of the battery cell to a certain extent. If the thickness of the carbon-containing coating is too thin, the deposited metal layer will be uneven, resulting in increased gas production of the battery cell. If the thickness of the carbon-containing coating is too thick, some active ions will be easily embedded in the carbon-containing coating, forming an SEI film. During charging and discharging, the SEI film is easily ruptured, resulting in increased gas production of the battery cell.

[0118] This application scheme thoroughly studies the impact of the negative electrode plate on the gas production behavior of battery cells. Exhaust components with matching exhaust rates are then designed for battery cells with different negative electrode plates. This allows for timely exhaust of gas within the battery cells, balancing the need for high negative electrode plate performance with high gas production. Furthermore, for battery cells with low gas production, there is no need for exhaust components with high exhaust capacity, thus reducing the impact of external water vapor intrusion on the battery during the exhaust process.

[0119] Among them, the exhaust rate of the exhaust component can be 2.0mL / day, 2.2mL / day, 2.5mL / day, 2.8mL / day, 3.1mL / day, 3.5mL / day, 3.8mL / day, 4.0mL / day, 4.5mL / day, 5.0mL / day, 5.5mL / day, 6.0mL / day, 6.5mL / day, 7.0mL / day, 7.5mL / day, 8.0mL / day, 8.5mL / day, 9.0mL / day, 9.5mL / day, 10.0mL / day, etc.

[0120] The exhaust rate of a vent assembly is defined as the volume of gas discharged from a battery cell in one day. A higher exhaust rate facilitates the discharge of gas from the battery cell. However, the presence of the vent assembly reduces the sealing of the battery system to a certain extent, allowing external moisture to easily enter the housing through the vent assembly, resulting in reduced battery cell performance. Therefore, it is not advisable to design a vent assembly with a relatively high exhaust rate simply to meet exhaust requirements.

[0121] Exhaust rate test principle: Under the condition of 23℃ and relative humidity of 0%, the test is carried out based on GB / T1038-2000 standard. Specifically, the exhaust assembly separates the low-pressure chamber and the high-pressure chamber. The high-pressure chamber is filled with about 10 5 The test gas is at a pressure of 0.1 MPa (i.e., 0.1 MPa). The volume of the low-pressure chamber is known. After the sample is sealed, the air in the low-pressure chamber is evacuated to near zero (i.e., evacuated) using a vacuum pump. The pressure increment ΔP in the low-pressure chamber is measured with a manometer to determine the amount of test gas that permeates the membrane (or sheet) from the high-pressure chamber to the low-pressure chamber as a function of time. However, the initial period, during which the gas permeation rate varies with time, must be excluded. The gas permeation rate and gas permeation coefficient can be calculated by the instrument's computer according to the specified program and output to a floppy disk or printed on a recording paper. Alternatively, the values ​​can be calculated using the test values.

[0122] In the present application, battery cells with different negative electrode plates are equipped with exhaust components with matching exhaust rates; this can balance the contradiction between high negative electrode plate performance requirements and high gas production.

[0123] In one embodiment, the thickness of the carbon-containing coating is 1 μm ≤ L ≤ 8 μm; for example, it can be 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, 4.0 μm, 4.5 μm, 5.0 μm, 5.5 μm, 6.0 μm, 6.5 μm, 7.0 μm, 7.5 μm, 8.0 μm, etc. In this embodiment, the thickness of the carbon-containing coating is relatively thin, which can reduce the probability of active ion embedding and reduce the gas production caused by side reactions. Therefore, it can be matched with exhaust components with a lower exhaust rate, can meet basic exhaust requirements, and can also reduce the intrusion of external water vapor. In this embodiment, the exhaust rate of the exhaust component can be: 2.0mL / day ≤ exhaust rate ≤8.0mL / day, which can be 2.0mL / day, 2.2mL / day, 2.5mL / day, 2.8mL / day, 3.1mL / day, 3.5mL / day, 3.8mL / day, 4.0mL / day, 4.5mL / day, 5.0mL / day, 5.5mL / day, 6.0mL / day, 6.5mL / day, 7.0mL / day, 7.5mL / day, 8.0mL / day, etc.

[0124] In one embodiment, the carbon content of the carbon-containing coating is 5%-50% based on the total mass of the carbon-containing coating. For example, it can be 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, etc. Among them, the carbon content in the carbon-containing coating to a certain extent will cause side reactions, resulting in increased gas production in the battery cell. By regulating the carbon content of the carbon-containing coating, the gas production caused by side reactions can be reduced. Therefore, it can be matched with an exhaust component with a lower exhaust rate, which can meet basic exhaust requirements while reducing the intrusion of external water vapor. In this embodiment, the exhaust rate of the exhaust component can be: 2.0 mL / day ≤ exhaust rate ≤ 8.0 mL / day, which can be 2.0 mL / day, 2.2 mL / day, 2.5 mL / day, 2.8 mL / day, 3.1 mL / day, 3.5 mL / day, 3.8 mL / day, 4.0 mL / day, 4.5 mL / day, 5.0 mL / day, 5.5 mL / day, 6.0 mL / day, 6.5 mL / day, 7.0 mL / day, 7.5 mL / day, and 8.0 mL / day.

[0125] In one embodiment, the water content of the negative electrode plate is 100ppm-600ppm. For example, it can be 100ppm, 200ppm, 300ppm, 400ppm, 500ppm, 600ppm, etc. Among them, the water content of the plate is tested by drying the plate in a vacuum oven. For the convenience of testing, a plate puncher with a diameter of 14mm is used to punch out a small disc sample with a diameter of 14mm from the dried plate. The mass of the disc sample is recorded as M1. Then, a current collector of the same area is weighed and its mass is recorded as M2. The above operation is usually performed in a drying room. The plate sample is placed in a penicillin bottle and sealed. The water content of the plate is measured using a Karl Fischer moisture meter and recorded as P1 (the instrument temperature is increased to 170°C). The water content P of the plate is then calculated according to P=P1 / (M1-M2). The presence of trace water easily reacts with the deposited metal to produce gas, increasing the gas production. By controlling the water content of the negative electrode plate, the gas production caused by the side reaction can be reduced. Therefore, an exhaust component with a smaller exhaust rate can be matched to meet the basic exhaust requirements while reducing the intrusion of external water vapor. In this embodiment, the exhaust rate of the exhaust component can be: 2.0mL / day ≤ exhaust rate ≤ 8.0mL / day, which can be 2.0mL / day, 2.2mL / day, 2.5mL / day, 2.8mL / day, 3.1mL / day, 3.5mL / day, 3.8mL / day, 4.0mL / day, 4.5mL / day, 5.0mL / day, 5.5mL / day, 6.0mL / day, 6.5mL / day, 7.0mL / day, 7.5mL / day, 8.0mL / day.

[0126] In one embodiment, the thickness of the carbon-containing coating is 8 μm ≤ L ≤ 15 μm; for example, the thickness may be 8.0 μm, 8.5 μm, 9.0 μm, 9.5 μm, 10.0 μm, 10.5 μm, 11.0 μm, 11.5 μm, 12.0 μm, 12.5 μm, 13.0 μm, 13.5 μm, 14.0 μm, 14.5 μm, 15.0 μm, etc. In this embodiment, the carbon-containing coating is relatively thick, and the gas production caused by side reactions is slightly greater. Therefore, it can be compatible with an exhaust component with a higher exhaust rate to promptly exhaust the generated gas. In this embodiment, the exhaust rate of the exhaust component can be: 3.0 mL / day ≤ exhaust rate ≤ 9.0 mL / day, which can be 3.0 mL / day, 3.2 mL / day, 3.5 mL / day, 3.8 mL / day, 4.1 mL / day, 4.5 mL / day, 4.8 mL / day, 5.0 mL / day, 5.5 mL / day, 6.0 mL / day, 6.5 mL / day, 7.0 mL / day, 7.5 mL / day, 8.0 mL / day, 8.5 mL / day, and 9.0 mL / day.

[0127] In one embodiment, the carbon content of the carbon-containing coating is 50%-90% based on the total mass of the carbon-containing coating. For example, it can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, etc. The carbon content is tested by burning the carbon-containing coating in a high-frequency induction furnace and then testing the carbon content using infrared absorption. The specific testing process is in accordance with the standard GB / T20123-2006 / ISO15350:2000. The carbon-containing coating has a relatively high carbon content, and the gas production due to side reactions is slightly higher. Therefore, it can be matched with an exhaust component with a higher exhaust rate to promptly exhaust the generated gas. In this embodiment, the exhaust rate of the exhaust component can be: 3.0 mL / day ≤ exhaust rate ≤ 9.0 mL / day, which can be 3.0 mL / day, 3.2 mL / day, 3.5 mL / day, 3.8 mL / day, 4.1 mL / day, 4.5 mL / day, 4.8 mL / day, 5.0 mL / day, 5.5 mL / day, 6.0 mL / day, 6.5 mL / day, 7.0 mL / day, 7.5 mL / day, 8.0 mL / day, 8.5 mL / day, and 9.0 mL / day.

[0128] In one embodiment, the water content of the negative electrode plate is 600ppm-1200ppm. For example, it can be 600ppm, 700ppm, 800ppm, 900ppm, 1000ppm, 1100ppm, 1200ppm, etc. Among them, the water content in the negative electrode plate is relatively high, and the gas production caused by the side reaction is slightly large. Therefore, it can be matched with an exhaust component with a larger exhaust rate to discharge the generated gas in time. In this embodiment, the exhaust rate of the exhaust component can be: 3.0mL / day≤exhaust rate≤9.0mL / day, which can be 3.0mL / day, 3.2mL / day, 3.5mL / day, 3.8mL / day, 4.1mL / day, 4.5mL / day, 4.8mL / day, 5.0mL / day, 5.5mL / day, 6.0mL / day, 6.5mL / day, 7.0mL / day, 7.5mL / day, 8.0mL / day, 8.5mL / day, 9.0mL / day.

[0129] In one embodiment, the electrode assembly further includes a positive electrode sheet, which includes a positive electrode active material. The residual alkali content of the positive electrode active material is 0% wt < 0.5% wt based on the total mass of the positive electrode active material. The residual alkali content includes one or more of oxides, hydroxides, carbonates, and nitrates of active ions. For example, the residual alkali content may be 0.01% wt, 0.05% wt, 0.1% wt, 0.15% wt, 0.18% wt, 0.21% wt, 0.25% wt, 0.30% wt, 0.35% wt, 0.40% wt, 0.45% wt, 0.5% wt, etc.

[0130] Taking sodium metal batteries as an example, residual substances such as sodium oxide, sodium hydroxide, sodium carbonate, and sodium nitrate are often present in the positive electrode active material. The presence of these substances can make the positive electrode active material alkaline. To test for residual alkalinity, refer to GB / T9725-2007, "General Rules for Potentiometric Titration of Chemical Reagents." Samples should be taken and the test solution prepared according to the product standard. Insert the specified electrodes, start the electromagnetic stirrer, and titrate with the specified standard titrant. Add approximately 90 percent of the required titration volume of the standard titrant from the burette and measure the potential or pH of the solution. Measure the potential or pH every time 1 mL or an appropriate amount of standard titrant is added. Measure the potential or pH every time 0.1 mL of standard titrant is added before and after the stoichiometric point. Continue titrating until the potential or pH does not change significantly. Record the burette reading and the measured potential or pH after each addition of the standard titrant for use in determining the titration endpoint graphically or using the second-order derivative method.

[0131] The positive electrode active material of the alkali metal battery is highly active, and side reactions are likely to occur during the preparation process to form residual alkali, and the residual alkali is not easy to separate, resulting in residual alkali remaining in the positive electrode active material. The presence of residual alkali is prone to side reactions, resulting in increased gas production. By regulating the residual alkali content in the positive electrode active material, the gas production caused by side reactions can be reduced. Therefore, an exhaust component with a smaller exhaust rate can be matched to meet basic exhaust requirements while reducing the intrusion of external water vapor. In this embodiment, the exhaust rate of the exhaust component can be: 2.0mL / day≤exhaust rate≤8.0mL / day, which can be 2.0mL / day, 2.2mL / day, 2.5mL / day, 2.8mL / day, 3.1mL / day, 3.5mL / day, 3.8mL / day, 4.0mL / day, 4.5mL / day, 5.0mL / day, 5.5mL / day, 6.0mL / day, 6.5mL / day, 7.0mL / day, 7.5mL / day, 8.0mL / day.

[0132] In one embodiment, the electrode assembly further comprises a positive electrode sheet, the positive electrode sheet comprises a positive electrode active material, and the specific surface area (BET) of the positive electrode active material is 2m 2 / g<Specific surface area≤7m 2 / g. For example, the specific surface area can be 2m 2 / g, 2.5m 2 / g、3m 2 / g, 3.5m 2 / g、4m 2 / g, 4.5m 2 / g、5m 2 / g, 5.5m 2 / g、6m 2 / g, 6.5m 2 / g、7m 2 / g, etc.

[0133] Specific surface area can be measured using the gas adsorption method. A smaller specific surface area can slow down surface side reactions. According to the BET gas adsorption method (GB / T 19587-2004), after heating and degassing the sample, the amount of gas adsorbed on the solid surface at different adsorption pressures is measured at a constant low temperature. Based on the BET multilayer adsorption theory and its formula, the monolayer adsorption capacity of the sample is calculated, thereby calculating the specific surface area per unit mass of the solid sample.

[0134] Among them, the specific surface area of ​​the positive electrode active material is large, which increases the contact surface between the positive electrode active material and the electrolyte, makes it easy to have side reactions, and leads to an increase in gas production. By regulating the specific surface area of ​​the positive electrode active material, the gas production caused by the side reactions can be reduced. Therefore, an exhaust component with a smaller exhaust rate can be matched to meet basic exhaust requirements while reducing the intrusion of external water vapor. In this embodiment, the exhaust rate of the exhaust component can be: 2.0mL / day≤exhaust rate≤8.0mL / day, which can be 2.0mL / day, 2.2mL / day, 2.5mL / day, 2.8mL / day, 3.1mL / day, 3.5mL / day, 3.8mL / day, 4.0mL / day, 4.5mL / day, 5.0mL / day, 5.5mL / day, 6.0mL / day, 6.5mL / day, 7.0mL / day, 7.5mL / day, 8.0mL / day.

[0135] In one embodiment, the electrode assembly further includes a positive electrode sheet, which includes a positive electrode active material. The carbon content of the positive electrode active material is 0.5% < carbon content ≤ 1.5% based on the total mass of the positive electrode active material. For example, the carbon content may be 0.5%, 0.8%, 1.0%, 1.2%, 1.5%, etc.

[0136] Among them, the carbon content of the positive electrode active material is prone to side reactions, resulting in increased gas production. The carbon source can be a coating material. By regulating the carbon content of the positive electrode active material, the gas production caused by the side reaction can be reduced. Therefore, an exhaust component with a smaller exhaust rate can be matched to meet basic exhaust requirements while reducing the intrusion of external water vapor. In this embodiment, the exhaust rate of the exhaust component can be: 2.0mL / day≤exhaust rate≤8.0mL / day, which can be 2.0mL / day, 2.2mL / day, 2.5mL / day, 2.8mL / day, 3.1mL / day, 3.5mL / day, 3.8mL / day, 4.0mL / day, 4.5mL / day, 5.0mL / day, 5.5mL / day, 6.0mL / day, 6.5mL / day, 7.0mL / day, 7.5mL / day, 8.0mL / day.

[0137] In one embodiment, the electrode assembly further comprises a positive electrode sheet, and the water content of the positive electrode sheet is 50ppm-400ppm. For example, it can be 50ppm, 80ppm, 120ppm, 160ppm, 220ppm, 280ppm, 320ppm, 350ppm, 400ppm, etc. Among them, the water content test of the electrode sheet is to dry the electrode sheet in a vacuum oven. For the convenience of testing, a 14mm diameter punching machine is used to punch out a small disc sample with a diameter of 14mm from the dried electrode sheet. The mass of the sample is recorded as M1. Then, a current collector of the same area is weighed and its mass is recorded as M2. The above operation is usually performed in a drying room. The electrode sample is placed in a penicillin bottle and sealed. The water content of the electrode sheet is measured using a Karl Fischer moisture meter and recorded as P1 (the instrument temperature is increased to 170°C). The water content P of the electrode sheet is then calculated according to P=P1 / (M1-M2). The presence of trace water easily reacts with the positive electrode active material to produce gas, increasing the gas production. By controlling the water content of the positive electrode, the gas production caused by the side reaction can be reduced. Therefore, an exhaust component with a smaller exhaust rate can be matched to meet the basic exhaust requirements while reducing the intrusion of external water vapor. In this embodiment, the exhaust rate of the exhaust component can be: 2.0mL / day≤exhaust rate≤8.0mL / day, which can be 2.0mL / day, 2.2mL / day, 2.5mL / day, 2.8mL / day, 3.1mL / day, 3.5mL / day, 3.8mL / day, 4.0mL / day, 4.5mL / day, 5.0mL / day, 5.5mL / day, 6.0mL / day, 6.5mL / day, 7.0mL / day, 7.5mL / day, 8.0mL / day.

[0138] In one embodiment, the electrode assembly further includes a positive electrode sheet, which includes a positive electrode active material. The residual alkali content of the positive electrode active material is 0.5% wt < 1.5% wt based on the total mass of the positive electrode active material. The residual alkali includes one or more of oxides, hydroxides, carbonates, and nitrates of active ions. For example, the residual alkali content may be 0.51% wt, 0.55% wt, 0.6% wt, 0.70% wt, 0.80% wt, 0.90% wt, 1.00% wt, 1.10% wt, 1.20% wt, 1.30% wt, 1.40% wt, 1.5% wt, etc.

[0139] In this embodiment, the residual alkali content in the positive electrode active material is relatively high, and the gas production caused by the side reaction is slightly large. Therefore, an exhaust component with a larger exhaust rate can be matched to discharge the generated gas in time. In this embodiment, the exhaust rate of the exhaust component can be: 3.0 mL / day ≤ exhaust rate ≤ 9.0 mL / day, which can be 3.0 mL / day, 3.2 mL / day, 3.5 mL / day, 3.8 mL / day, 4.1 mL / day, 4.5 mL / day, 4.8 mL / day, 5.0 mL / day, 5.5 mL / day, 6.0 mL / day, 6.5 mL / day, 7.0 mL / day, 7.5 mL / day, 8.0 mL / day, 8.5 mL / day, and 9.0 mL / day.

[0140] In one embodiment, the electrode assembly further comprises a positive electrode sheet, the positive electrode sheet comprises a positive electrode active material, and the specific surface area of ​​the positive electrode active material is 7m 2 / g<Specific surface area≤15m 2 / g. For example, it can be 8m 2 / g、8.5m 2 / g、9m 2 / g, 9.5m 2 / g、10m 2 / g, 10.5m 2 / g、11m 2 / g, 11.5m 2 / g、12m 2 / g, 12.5m 2 / g、13m 2 / g, 13.5m 2 / g、14m 2 / g, 14.5m 2 / g、15m 2 / g, etc.

[0141] In this embodiment, the specific surface area of ​​the positive electrode active material is relatively large, and the gas production caused by the side reaction is slightly large. Therefore, it can be matched with an exhaust component with a larger exhaust rate to discharge the generated gas in a timely manner. In this embodiment, the exhaust rate of the exhaust component can be: 3.0 mL / day ≤ exhaust rate ≤ 9.0 mL / day, which can be 3.0 mL / day, 3.2 mL / day, 3.5 mL / day, 3.8 mL / day, 4.1 mL / day, 4.5 mL / day, 4.8 mL / day, 5.0 mL / day, 5.5 mL / day, 6.0 mL / day, 6.5 mL / day, 7.0 mL / day, 7.5 mL / day, 8.0 mL / day, 8.5 mL / day, and 9.0 mL / day.

[0142] In one embodiment, the electrode assembly further includes a positive electrode sheet, which includes a positive electrode active material. The carbon content of the positive electrode active material is 1.5% < carbon content ≤ 2.5% based on the total mass of the positive electrode active material. For example, the carbon content can be 1.5%, 1.8%, 2.0%, 2.2%, 2.5%, etc. The carbon content is tested by burning the positive electrode active material in a high-frequency induction furnace and then measuring the carbon content using an infrared absorption method. The specific testing process is in accordance with the standard GB / T20123-2006 / ISO15350:2000.

[0143] In this embodiment, the carbon content in the positive electrode active material is relatively high, and the gas production caused by the side reaction is slightly large. Therefore, an exhaust component with a larger exhaust rate can be matched to discharge the generated gas in a timely manner. In this embodiment, the exhaust rate of the exhaust component can be: 3.0 mL / day ≤ exhaust rate ≤ 9.0 mL / day, which can be 3.0 mL / day, 3.2 mL / day, 3.5 mL / day, 3.8 mL / day, 4.1 mL / day, 4.5 mL / day, 4.8 mL / day, 5.0 mL / day, 5.5 mL / day, 6.0 mL / day, 6.5 mL / day, 7.0 mL / day, 7.5 mL / day, 8.0 mL / day, 8.5 mL / day, and 9.0 mL / day.

[0144] In one embodiment, the water content of the positive electrode plate is 400ppm-1000ppm. For example, it can be 400ppm, 500ppm, 600ppm, 700ppm, 800ppm, 900ppm, 1000ppm, etc. Among them, the water content in the positive electrode plate is relatively high, and the gas production caused by the side reaction is slightly large. Therefore, it can be matched with an exhaust component with a larger exhaust rate to discharge the generated gas in time. In this embodiment, the exhaust rate of the exhaust component can be: 3.0mL / day≤exhaust rate≤9.0mL / day, which can be 3.0mL / day, 3.2mL / day, 3.5mL / day, 3.8mL / day, 4.1mL / day, 4.5mL / day, 4.8mL / day, 5.0mL / day, 5.5mL / day, 6.0mL / day, 6.5mL / day, 7.0mL / day, 7.5mL / day, 8.0mL / day, 8.5mL / day, 9.0mL / day.

[0145] In one embodiment, the battery cell further includes an electrolyte, the electrolyte is filled in the receiving cavity, and the conductivity of the electrolyte is 5 ms / cm≤conductivity≤15 ms / cm.

[0146] Conductivity is the ability of a solution to conduct electric current, expressed in numbers. The electrolyte conducts ions between the positive and negative electrodes. The conductivity of the electrolyte depends on the concentration of mobile ions and the migration rate of ions under a given electric field. In this embodiment, the conductivity of the electrolyte is 5-15ms / cm, for example, 5ms / cm, 8ms / cm, 10ms / cm, 12ms / cm, 14ms / cm, 15ms / cm, etc. High conductivity enables rapid migration of ions, improving the charging capacity and energy density of the entire battery cell. However, high conductivity will increase gas production.

[0147] The conductivity of the electrolyte generally refers to the reciprocal of the resistance of one cubic centimeter of liquid at 25°C, expressed in Ω. -1 cm -1 Or expressed in S / cm.

[0148] Conductivity test principle: The conductivity of a solution is related to its resistance. A large resistance indicates poor conductivity, while a small resistance indicates good conductivity. According to Ohm's law, at a constant temperature, the resistance of a solution is inversely proportional to the vertical cross-sectional area of ​​the electrodes and directly proportional to the distance between the electrodes. The unit of resistance is ohm (Ω); the unit of resistivity is ohm (Ω.M).

[0149] National standards for parameter testing:

[0150] The conductivity of the electrolyte can be measured using instruments and methods known in the art, for example, according to the HG / T4067-2015 standard.

[0151] Test method:

[0152] (1) Density meter method, also known as arbitration method.

[0153] The instrument measurement temperature was set to 20°C, the sample was injected into the measurement cell of the instrument, the measurement was performed and the data was read.

[0154] (2) Density meter method

[0155] Use a dry, clean, corrosion-resistant sample bottle to take about 100 mL of sample, seal it and place it in a constant temperature water bath at 25℃±0.5℃, shake it from time to time. When the sample temperature is constant, replace the sample bottle cap with a rubber stopper with an electrode. When the temperature is within the range of 25℃±0.5℃, read the data in the conductivity meter, which is the conductivity of the tested sample.

[0156] This setting can make the exhaust rate and electrolyte conductivity more accurately matched, and can improve the charging capacity and energy density of the battery cell while taking into account the safety performance and service life of the battery cell.

[0157] According to some embodiments of the present application, the electrolyte includes a first component, which includes one or a mixture of two or more of dimethyl carbonate, 2-methyltetrahydrofuran, diethylene glycol dimethyl ether, diethylene glycol dimethyl ether, succinonitrile, glutaronitrile, methyl formate, ethyl formate, methyl acetate, ethyl acetate, methyl acrylate, dimethyl sulfite, diethyl sulfite, methyl ethyl sulfite, and 3-methyl-2-butanone. The above electrolyte components have at least one of high conductivity and low viscosity. When applied to the electrolyte system of a battery cell, they can achieve rapid ion migration and improve the charging capacity and energy density of the entire battery cell.

[0158] In the present application, at least one of a high-conductivity substance and a low-viscosity substance is introduced into the electrolyte system. This can improve the energy density and charging capacity of the battery cell. However, the electrolyte components with high conductivity and low viscosity are often some chain-like low-molecular-weight organic substances with high activity. They are more likely to undergo oxidation / reduction reactions during the charge and discharge process, which increases the gas production of the battery cell and causes an increase in the internal pressure of the battery cell, resulting in a series of adverse consequences. In the present application, the gas production behavior of high-conductivity and low-viscosity electrolytes is fully studied, and exhaust components with different exhaust rates are matched for battery cells with different electrolyte components; it can balance the contradiction between high energy density and charging capacity and high gas production. At the same time, for some battery cells that do not require high conductivity, there is no need to match them with exhaust components with large exhaust capacity, so as to reduce the impact of external water vapor intrusion on the battery cell during the exhaust process.

[0159] In one embodiment, the content of the first component is 5%-85% based on the total mass of the electrolyte. The content of the first component is calculated based on the total mass of the electrolyte to calculate the proportion of the first component in the total electrolyte.

[0160] In one embodiment, the content of the first component is 15%-35%, and the content of the first component can be selected from 5%, 10%, 20%, 30%, 40%, 50%, etc. In this case, the content of the first component is relatively low, and the gas production of the battery cell is relatively small. This can be matched with a vent assembly with a low exhaust rate to promptly exhaust gas and reduce the probability of external moisture entering the interior of the housing through the vent assembly, thereby maintaining the sealing of the battery cell.

[0161] In another embodiment, the content of the first component is greater than or equal to 50% based on the total mass of the electrolyte. In one embodiment, the content of the first component is 65%-85%. The content of the first component can be selected from 50%, 55%, 60%, 70%, 80%, 90%, 100%, etc. In this case, the content of the first component is relatively high, and the gas production of the battery cell is relatively high. Therefore, matching it with a vent assembly with a high exhaust rate can timely exhaust the gas and quickly balance the air pressure inside the battery cell housing and the external environment.

[0162] In one embodiment, the positive electrode plate includes a positive electrode active material, the positive electrode active material includes a first type of material, the first type of material includes a first ternary material, and the mass content of nickel in the first ternary material is greater than or equal to 50% and less than 100% (50%≤nickel content<100%).

[0163] In a battery cell, the positive electrode active material acts as an ion source, providing conductive ions that travel back and forth between the positive and negative electrodes during the reversible charge and discharge process. Therefore, it has a significant impact on the energy density of the battery cell. The specific capacity of the positive electrode active material refers to the amount of charge that can be stored per unit mass of the material; the higher the specific capacity, the higher the energy density of the battery cell.

[0164] The "ternary" in the ternary positive electrode material refers to a polymer containing nickel (Ni), cobalt (Co), and manganese (Mn) or three metal elements of nickel (Ni), cobalt (Co), and aluminum (Al). Materials containing three transition metal oxides of nickel, cobalt, and manganese or three metal oxides of nickel, cobalt, and aluminum can be used as active positive electrode materials in lithium batteries. Each element in the ternary material plays an important role, and the characteristics of each element also restrict the performance of the battery. Take the nickel-cobalt-manganese ternary material as an example: Ni exhibits high capacity and low safety; Co exhibits high cost and high stability; Mn exhibits high safety and low cost. In order to increase the energy density of the battery, the current mainstream view is to increase the nickel content, but the increase in nickel content will lead to stronger oxidation of the positive electrode material, which will cause the electrolyte to oxidize and produce gas during the use of the battery cell.

[0165] In this embodiment, the nickel content of the first ternary material can be 50%, 60%, 70%, 80%, 90%, 99%, etc. As previously mentioned, increasing the nickel content in the ternary material can improve the energy density of the battery cell. However, as the nickel content in the ternary material increases, the material surface becomes more active, thereby increasing the electrochemical and chemical reactivity of the ternary material in contact with the electrolyte. This causes the ternary material to become oxidizing, slowly oxidizing the electrolyte and releasing gas, which increases the gas production of the battery cell.

[0166] This application scheme thoroughly studies the gas production behavior of positive electrode active materials and provides exhaust assemblies with different exhaust rates for battery cells containing different positive electrode active materials. This allows for timely exhaust of gas within the battery cells, balancing the conflict between high energy density requirements and high gas production. Furthermore, for battery cells that do not require high conductivity, there is no need for exhaust assemblies with large exhaust capacities, thus reducing the impact of external water vapor intrusion on the battery during the exhaust process.

[0167] In the present application, battery cells with different positive electrode active materials are equipped with exhaust components with different exhaust rates; this can balance the contradiction between high energy density requirements and high gas production.

[0168] In one embodiment, the positive electrode active material includes a first ternary material, and the mass content of nickel in the first ternary material is greater than or equal to 50% and less than 80% (50%≤nickel content<80%), which can be 50%, 60%, 70%, 75%, 79%, etc.

[0169] In this case, the nickel content in the first ternary material is relatively low, the positive electrode material has relatively low oxidizability, and the battery cell produces less gas. This can be matched with a venting component with a lower exhaust rate, which can meet basic ventilation requirements while reducing the intrusion of external moisture.

[0170] In one embodiment, the mass content of nickel in the first ternary material is greater than or equal to 50% and less than or equal to 60%. Through this configuration, the battery cell capacity can be increased while taking into account the safety performance and service life of the battery cell.

[0171] In one embodiment, the first ternary material has a median particle size Dv50 of 2-4 μm.

[0172] Dv50 refers to the particle diameter at 50% cumulative volume. Larger particle sizes increase the contact area with the electrolyte and other components, making side reactions more likely to produce gas. This configuration allows for the timely removal of gas from the battery cell, maintaining the internal pressure within the cell within a normal range.

[0173] In one embodiment, the mass content of cobalt in the first ternary material is 12%-18%. For example, it can be 12%, 13%, 14%, 15%, 16%, 17%, or 18%. By adjusting the mass content of cobalt, the stability of the positive electrode active material can be improved.

[0174] In one embodiment, the first ternary material has a nickel content of greater than or equal to 50% and less than or equal to 60% by mass, a cobalt content of 12%-18% by mass, and a median particle size Dv50 of 2-4 μm. This material is generally used as a high-power positive electrode active material. This positive electrode active material has a high power and can effectively improve the power performance of the battery, but it also has the problem of gas generation. Therefore, a relatively large gas exhaust rate within the gas exhaust rate range corresponding to a nickel content of greater than 50% and less than 80% in the first ternary material is matched to meet the gas exhaust requirements and maintain the battery internal pressure within a normal range.

[0175] In one embodiment, the positive electrode active material includes a first ternary material, and the mass content of nickel in the first ternary material is greater than or equal to 80%, and can be 80%, 85%, 90%, 95%, 99%, etc.

[0176] In this embodiment, the nickel content of the first ternary material is relatively high, the positive electrode material is relatively oxidizable, and the battery cell produces a large amount of gas. Therefore, matching it with an exhaust component with a high exhaust rate can timely exhaust the gas.

[0177] In one embodiment, based on the total mass of the positive electrode active material, the content of the first ternary material is greater than or equal to 50%, and can be 50%, 60%, 70%, 80%, 90%, 100%, etc.

[0178] Wherein, the positive electrode active material includes a first ternary material, and when the content of the first ternary material is greater than or equal to 50% based on the total mass of the positive electrode active material, in addition to the first ternary material, the positive electrode active material may include at least one of a second ternary material and a lithium iron manganese phosphate material. The nickel content of the second ternary material differs from the nickel content of the first ternary material. By controlling the content of the first ternary material, the cost of the positive electrode material can be reduced while increasing the energy density. In this case, the above-mentioned exhaust assembly can be used.

[0179] In one embodiment, the first ternary material includes one or more of single crystal particles and polycrystalline particles.

[0180] Ternary materials can be divided into single crystal and polycrystalline materials based on their crystal morphology. Single crystals are crystals that grow from a single nucleus. Basically, their internal structure is a complete lattice, while polycrystalline materials are composed of many single crystal particles with different orientations. Polycrystalline and single crystals are mixed in the ternary positive electrode materials of lithium-ion batteries. Polycrystalline materials have higher specific capacity, good power performance and low cost. However, the skeleton structure of polycrystalline ternary materials is poorly robust. During the battery cycle, especially under high-voltage charge and discharge, the continuous expansion and contraction of the particles can easily cause microcracks between the grains of the material, resulting in poor crystal structure stability. At the same time, the entry of electrolyte into the microcracks exacerbates the side reactions of the electrolyte on the surface of the positive electrode material and produces gas. By matching the exhaust components, the exhaust requirements can be met and the internal air pressure of the battery can be maintained within the normal range.

[0181] According to some embodiments of the present application, the exhaust assembly includes a breathable membrane assembly, which includes a breathable membrane. The breathable membrane is configured to allow gas inside the battery cell to be discharged through the breathable membrane, and the breathable membrane has a breathability rate of 2.0-10.0 mL / day.

[0182] According to some embodiments of the present application, the breathable membrane assembly includes a breathable membrane made of a breathable material with excellent air permeability, allowing gas molecules to pass through. By selecting the breathable membrane assembly as the exhaust assembly, the battery cells can be sealed to allow internal gas to be discharged through the breathable membrane, promptly discharging the gas inside the battery casing to the outside of the casing, thereby preventing excessive pressure inside the battery casing.

[0183] Furthermore, the breathable membrane also has liquid-isolating properties, preventing liquid from passing through, so it can prevent the electrolyte from overflowing while discharging gas. In addition, the breathable membrane can also block external water vapor, dust and impurities from entering the battery cell, protecting the internal environment of the battery cell and effectively improving the reliability of the battery cell. The breathable membrane also has good weather resistance, chemical corrosion resistance, and structural stability. If it is an automotive power battery, it also needs to have oleophobicity. Therefore, the material of the breathable membrane can be selected from polymer materials, such as polytetrafluoroethylene, polypropylene, etc. In addition, since the generation of gas inside the battery will cause the internal pressure to rise rapidly, the breathable membrane needs to have certain mechanical strength and elasticity.

[0184] The air permeability rate of the breathable membrane assembly depends on the properties of the breathable membrane. A polymer membrane with a certain porosity can be selected as the breathable membrane. Breathable membranes with different air permeability rates can be prepared by selecting materials with different porosities. For example, the air permeability rate of the breathable membrane can be 2.0 mL / day, 2.2 mL / day, 2.5 mL / day, 2.8 mL / day, 3.1 mL / day, 3.5 mL / day, 3.8 mL / day, 4.0 mL / day, 4.5 mL / day, 5.0 mL / day, 5.5 mL / day, 6.0 mL / day, 6.5 mL / day, 7.0 mL / day, 7.5 mL / day, 8.0 mL / day, 8.5 mL / day, 9.0 mL / day, 9.5 mL / day, 10.0 mL / day, etc. The air permeability test conditions of the breathable membrane are 23° C., 0% RH (humidity is 0%), and 0.1 MPa air pressure. The test method refers to the standard GB / T1038-2000.

[0185] According to some embodiments of the present application, the film thickness of the breathable membrane is 20 μm ≤ film thickness ≤ 100 μm. For example, it can be 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, or 100 μm. Through this setting, the balance between the strength, air permeability, and water permeability of the breathable membrane can be balanced, so that the breathable membrane has higher strength, reduces the probability of deformation and damage, and improves the ability to block water vapor while meeting the need for ventilation. In other words, the breathable membrane can meet the need for ventilation, increase water resistance, and reduce the intrusion of external water vapor.

[0186] According to some embodiments of the present application, the ratio of the breathable area of ​​the breathable membrane to the area of ​​the wall where the breathable membrane assembly is located is 5%-10%, for example, 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0187] Among them, venting assemblies with different exhaust rates can be manufactured based on the air permeability rate of the breathable membrane itself, and the exhaust rate can also be adjusted by adjusting the air permeability area of ​​the breathable membrane. Adjusting the air permeability area can reduce the intrusion of external water vapor into the battery cells while meeting the ventilation requirements.

[0188] According to some embodiments of the present application, the vent assembly 90 includes a one-way valve 30, which is configured to actuate and release gas from the battery cell 20 when the internal gas pressure of the battery cell 20 reaches a threshold value. In other words, the one-way valve 30 is used to exhaust gas from the interior of the battery cell housing. That is, the one-way valve 30 can be opened in one direction to exhaust gas, so that the gas inside the battery cell housing can be discharged to the outside of the housing through the one-way valve 30.

[0189] Please refer to Figure 3, which is a schematic cross-sectional view of a one-way valve according to one or more embodiments. According to some embodiments of the present application, the one-way valve 30 includes a valve body 31 and a valve core 32. The valve body 31 has a valve cavity 313 therein. The valve body 31 is provided with an air inlet 313a and an air outlet 313b. The air inlet 313a is used to connect the valve cavity 313 with the interior of the housing, and the air outlet 313b is used to connect the valve cavity 313 with the exterior of the housing. The valve core 32 is disposed in the valve cavity 313 and is used to block the air inlet passage of the valve cavity 313. The valve core 32 is configured to open the air inlet passage under the action of the gas inside the housing and release the gas inside the battery cell.

[0190] As shown in Figure 3, Figure 3 (a) is a schematic diagram of the one-way valve in the closed state; Figure 3 (b) is a schematic diagram of the one-way valve in the open state. The valve core 32 includes an elastic member 322 and a blocking member 321. The blocking member 321 includes a pressing portion 3212 and a sealing portion 3211. The elastic member 322 provides an elastic force F1 to the blocking member 321, and the blocking member 321 is compressed to block the air inlet 313a. When the force F2 of the gas inside the shell acting on the blocking member 321 is greater than the elastic force F1 of the elastic member, the gas inside the shell can overcome the elastic force of the elastic member and push the blocking member 321 to open the air inlet 313a, allowing the gas inside the shell to enter the valve cavity 313 and then be discharged to the outside of the shell through the air outlet 313b. On the contrary, after the gas inside the shell is discharged and the force F2 of the gas inside the shell acting on the blocking member 321 is smaller than the elastic force F1 of the elastic member, the elastic member 322 can drive the blocking member 321 to reset to block the air inlet 313a.

[0191] Specifically, when the air pressure inside the shell increases to a certain value P1, the air pressure applies a force F2 to the lower surface of the sealing member 321. When F2 is greater than the spring compression force F1, the sealing interface fails, and the gas inside the shell is discharged to the outside of the shell through the channel inside the valve body 31. As the gas inside the shell is discharged, the internal air pressure drops. When the air pressure reaches a certain value P2, the valve body 31 closes to achieve sealing. The valve body 31 can be opened and closed repeatedly to exhaust and vent air, so that the air pressure inside the shell is maintained between P1-P2, thereby preventing the pressure relief mechanism from opening the valve prematurely due to excessive air pressure inside the shell. In other words, a one-way valve requires a certain pressure threshold to open.

[0192] According to some embodiments of the present application, the opening pressure of the valve core is greater than or equal to 0.2 MPa; further, greater than or equal to 0.4 MPa; and further, greater than or equal to 0.8 MPa. For example, the opening pressure can be 0.20 MPa, 0.25 MPa, 0.30 MPa, 0.35 MPa, 0.40 MPa, 0.45 MPa, 0.50 MPa, 0.55 MPa, 0.60 MPa, 0.65 MPa, 0.70 MPa, 0.75 MPa, 0.80 MPa, etc.

[0193] The one-way valve opening pressure test method and principle can be tested based on the helium leakage standard. The helium leakage standard is defined as follows: if the leakage rate is less than 10^-6Pa.m^3 / s, the system is considered to be sealed; if the leakage rate is greater than 10^-6Pa.m^3 / s, it indicates that there is a gas leak in the system.

[0194] During testing, the test chamber is sealed with a one-way valve and filled with helium. The amount of helium in the test chamber environment is monitored using a helium detector. If helium is detected and the leakage rate is greater than 10^-6Pa.m^3 / s, it means that the test chamber is no longer sealed and helium is leaking out. The helium leakage rate is continuously monitored. When the leakage rate is greater than 10^-5Pa.m^3 / s, the one-way valve is determined to be open for release. The pressure in the test chamber at this time is recorded as the opening pressure of the one-way valve.

[0195] According to some embodiments of the present application, 0.2MPa is suitable for when the pressure resistance of the battery cell is low and the gas production rate and gas production volume of the electrode assembly are large. At this time, the gas inside the shell can push the valve core to open the air inlet channel when the gas production volume is low, so that the gas inside the shell can enter the valve cavity and then be discharged to the outside of the shell through the gas outlet, which is conducive to timely discharge of gas produced by the battery cell and maintaining normal internal pressure of the battery cell; 0.4MPa is suitable for when the pressure resistance of the battery cell is medium and the gas production rate and gas production volume of the electrode assembly are medium. At this time, the gas inside the shell needs to reach 0.4MPa to push the valve core to open the air inlet channel, so that the gas inside the shell can enter the valve cavity and then be discharged to the outside of the shell through the gas outlet, which is conducive to timely discharge of gas produced by the battery cell and maintaining normal internal pressure of the battery cell; The gas produced by the single cell is discharged, and while the internal pressure of the battery cell is maintained at normal, the repeated opening of the valve core caused by repeated changes in the internal air pressure of the battery cell is reduced, which is beneficial to improving the sealing and usage stability of the battery cell; 0.8MPa is suitable for battery cells with strong pressure resistance and when the gas production rate and gas production volume of the electrode assembly are small, the gas inside the shell needs to reach 0.8MPa to push the valve core to open the air inlet channel, so that the gas inside the shell can enter the valve cavity and then be discharged to the outside of the shell through the outlet. While being able to discharge the gas produced by the battery cell in time and maintain the internal pressure of the battery cell at normal, the repeated opening of the valve core caused by repeated changes in the internal air pressure of the battery cell is further reduced, which is beneficial to improving the sealing and usage stability of the battery cell.

[0196] According to some embodiments of the present application, the exhaust assembly includes a one-way valve, and the opening pressure of the one-way valve is 0.3 MPa-0.5 MPa, for example, 0.3 MPa, 0.35 MPa, 0.4 MPa, 0.45 MPa, 0.5 MPa, etc.

[0197] Through the above-mentioned arrangement, the gas generated inside the battery cell can be discharged in time to maintain the normal internal pressure of the battery cell, and the situation of premature braking and pressure relief of the one-way valve caused by repeated changes in the internal pressure of the battery cell during use can be reduced, which is beneficial to improving the use stability of the battery cell and ultimately improving the service life and reliability of the battery cell.

[0198] According to some embodiments of the present application, the structure of the exhaust assembly can be selected based on the required exhaust rate of the exhaust assembly. The exhaust assembly can include a breathable membrane assembly, i.e., the breathable membrane assembly is selected as the exhaust assembly. The exhaust assembly can include a one-way valve, i.e., the one-way valve is selected as the exhaust assembly. In other embodiments, the exhaust assembly can include both a one-way valve and a breathable membrane assembly.

[0199] According to some embodiments of the present application, the exhaust assembly may be a breathable membrane assembly or a one-way valve. For example, a breathable membrane assembly including a breathable membrane having a permeability rate of 2.0-10.0 mL / day may be used alone, or a one-way valve having an opening pressure of 0.3 MPa-0.5 MPa may be used alone.

[0200] According to some embodiments of the present application, the positive electrode sheet is designed to meet the following requirements: 0% wt < residual alkali content ≤ 0.5% wt, 50ppm < water content ≤ 400ppm, 2m 2 / g<BET≤7m 2 / g, 0.5%<carbon content ≤1.5%; the negative electrode design meets the following requirements: the carbon coating thickness L meets 1μm≤L≤8μm, the proportion of substrate carbon material to substrate weight meets 5%~50%, 100ppm≤negative electrode sheet water content ≤600ppm; the electrolyte conductivity design meets the following requirements: electrolyte conductivity 0.5ms / cm≤S≤5ms / cm; when one or more of the positive electrode sheet, negative electrode sheet, and electrolyte meet the above conditions, the battery cell can be optionally equipped with a breathable membrane assembly, and the breathable membrane permeability rate must meet 2ml / day (D)-10mL / D, corresponding to the specified breathable membrane specific parameters: 20μm≤membrane thickness≤100μm, 5%≤the proportion of breathable area to wall area≤10%.

[0201] According to some embodiments of the present application, the positive electrode design meets the following requirements: 0.5% wt < residual alkali content ≤ 1.5% wt, 400 ppm < water content ≤ 1000 ppm, 7m 2 / g<BET≤15m 2 / g, with a carbon content of 1.5% to 2.5%; the negative electrode design meets the following requirements: the negative electrode surface is coated with a carbon-containing element, the effective material on the negative electrode surface is a carbon-containing element coating, the electrode single-side coating thickness L meets 8μm < L ≤ 15μm, the negative electrode substrate carbon material ratio to substrate weight meets 50% to 90%, and the negative electrode electrode water content is 600ppm < ≤ 1200ppm; the electrolyte conductivity design meets the following requirements: the electrolyte conductivity is 5ms / cm ≤ S ≤ 15ms / cm. When one or more of the positive electrode, negative electrode, and electrolyte meet the above requirements, the battery cell can be equipped with a one-way valve as a venting component. When the one-way valve is open, the internal pressure of the battery cell is 0.3MPa-0.5MPa, that is, the one-way valve opening pressure is 0.3MPa-0.5MPa.

[0202] According to some embodiments of the present application, the exhaust assembly 90 includes a breathable membrane assembly 40 and a one-way valve 30, and the wall has a first exhaust hole 291, which connects the inside of the shell with the outside of the shell, and the battery cell 20 is configured so that the gas discharged through the first exhaust hole 291 flows through the one-way valve 30 and the breathable membrane assembly 40.

[0203] As shown in Figure 2, the first vent 291 connects the interior of the housing with the exterior of the housing. That is, the first vent 291 is a through hole, allowing gas inside the battery cell 20 housing to be discharged through the first vent 291, thereby regulating the pressure inside the battery cell 20 housing. The battery cell 20 is configured so that the gas discharged through the first vent 291 flows through the one-way valve 30 and the breathable membrane assembly 40. This means that when the gas flows through the first vent 291, it also flows through the one-way valve 30 and the breathable membrane assembly 40, which belong to the same vent assembly 90; in other words, the gas exhaust path needs to flow through both the one-way valve 30 and the breathable membrane assembly 40 simultaneously. Alternatively, the one-way valve 30 and the breathable membrane assembly 40, which belong to the same vent assembly 90, are connected in series. When the gas flows through the vent assembly 90, it flows sequentially through the one-way valve 30 and the breathable membrane assembly 40 in the vent assembly 90. The gas may first flow through the breathable membrane assembly 40 and then through the one-way valve 30, or it may first flow through the one-way valve 30 and then through the breathable membrane assembly 40. The order of flow can be set as needed, but both structures need to flow through, rather than having some gas flow only through the one-way valve 30 and be discharged, while another portion of gas flows only through the breathable membrane assembly 40. The end cap 21 may be provided with a single first exhaust hole 291, or it may be provided with multiple first exhaust holes 291. When there are multiple first exhaust holes 291, each first exhaust hole 291 is equipped with a set of exhaust assemblies 90, and when the gas is discharged through the first exhaust hole 291, it will flow through the one-way valve 30 and breathable membrane assembly 40 in the exhaust assembly 90 provided at the first exhaust hole 291.

[0204] In this embodiment, by arranging the breathable membrane assembly 40 and the one-way valve 30 in series, the presence of the one-way valve 30 can control the battery cell to not be in a breathable state all the time, but only activate the one-way valve 30 to exhaust when the gas accumulates to a certain threshold, which can protect the sealing of the battery cell 20 and reduce the risk of external water vapor entering the interior of the battery cell 20; at the same time, the presence of the breathable membrane 41 can, on the one hand, prevent the overflow of the electrolyte, and on the other hand, when the one-way valve 30 is open, the breathable membrane 41 can achieve the sealing of the battery cell, so that the battery cell 20 can discharge the internal gas through the breathable membrane 41 and the one-way valve 30 in a closed state, thereby improving the disadvantage that when the one-way valve 30 is exhausting, the battery cell 20 system is in an open state and is easily invaded by external water vapor.

[0205] According to some embodiments of the present application, when the exhaust assembly 90 includes a breathable membrane assembly 40 and a one-way valve 30, and the breathable membrane assembly 40 and the one-way valve 30 are connected in series, breathable membranes 41 with different permeability rates and one-way valves 30 with different opening pressures can be used.

[0206] According to some embodiments of the present application, when connected in series, the opening pressure of the one-way valve 30 can be greater than or equal to 0.4 MPa, and the air permeability rate of the air permeable membrane of the air permeable membrane assembly 40 is 2-10 mL / day.

[0207] Please refer to Figure 4, which is a schematic diagram of a partially exploded structure of a battery cell according to one or more embodiments. According to some embodiments of the present application, the exhaust assembly 90 includes a breathable membrane assembly 40 and a one-way valve 30. The wall portion has first and second exhaust holes 291 and 293 spaced apart. The first and second exhaust holes 291 and 293 respectively connect the interior and exterior of the housing. The battery cell 20 is configured such that gas exhausted through the first exhaust hole 291 flows through the one-way valve 30, and gas exhausted through the second exhaust hole 293 flows through the breathable membrane assembly 40.

[0208] The first vent hole 291 connects the inside and outside of the housing, and the second vent hole 293 also connects the inside and outside of the housing. In other words, the two are independent holes that can simultaneously exhaust gas to regulate the pressure inside the housing of the battery cell 20. The end cap 21 may be provided with one first vent hole 291 and one second vent hole 293, or may be provided with multiple first vent holes 291 and multiple second vent holes 293. The battery cell 20 is configured so that gas discharged through the first vent 291 flows through the one-way valve 30, and gas discharged through the second vent 293 flows through the breathable membrane assembly 40. This means that gas can be discharged from the battery cell 20 through both the first vent 291 and the second vent 293 simultaneously. When discharged through the first vent 291, it flows through the one-way valve 30, and when discharged through the second vent 293, it flows through the breathable membrane assembly 40. In other words, the one-way valve 30 and the breathable membrane assembly 40 are connected in parallel. When gas flows through the vent assembly 90, it can simultaneously flow through the one-way valve 30 and the breathable membrane assembly 40 in the vent assembly 90. That is, some gas flows only through the one-way valve 30 for discharge, and some gas flows only through the breathable membrane assembly 40 for discharge. When there are multiple first vents 291, each first vent 291 is equipped with a one-way valve 30; when there are multiple second vents 293, each second vent 293 is equipped with a breathable membrane assembly 40.

[0209] In this embodiment, by arranging the breathable membrane assembly 40 in parallel with the one-way valve 30, when the internal pressure of the battery cell 20 is low, exhaust is primarily discharged through the breathable membrane assembly 40. When the internal pressure of the battery cell 20 is high, the one-way valve 30 opens to discharge air, and the breathable membrane assembly 40 also discharges air. This reduces the problem of frequent opening of the one-way valve 30 caused by unstable internal pressure of the battery cell 20, reduces the risk of external water vapor intrusion, and improves the sealing of the battery cell 20 system. At the same time, when the air pressure is low, gas can be promptly discharged through the breathable membrane assembly 40, which helps the exhaust assembly 90 adapt to different air pressure environments and improves the flexibility of the exhaust assembly 90.

[0210] According to some embodiments of the present application, when the exhaust assembly 90 includes a breathable membrane assembly 40 and a one-way valve 30, and the breathable membrane assembly 40 and the one-way valve 30 are connected in parallel, breathable membranes 41 with different permeability rates and one-way valves 30 with different opening pressures can be used.

[0211] According to some embodiments of the present application, the opening pressure of the one-way valve 30 in the parallel exhaust assembly 90 is greater than or equal to 0.4 MPa, the air permeability rate of the air permeable membrane of the air permeable membrane assembly 40 satisfies the requirement of being greater than 0 and less than or equal to 15 mL / D, and the water permeability satisfies the requirement of being 10 -4 MPa. Water vapor barrier performance (water permeability): tested in accordance with standard GB / T21529-2008.

[0212] According to some embodiments of the present application, the exhaust assembly uses a breathable membrane assembly and a one-way valve arranged in series, or the breathable membrane assembly and the one-way valve arranged in parallel. In other embodiments, the one-way valve 30 and the breathable membrane assembly 40 in the exhaust assembly can be mixed, that is, the exhaust assembly can include both the one-way valve 30 and the breathable membrane assembly 40 in series, or in parallel.

[0213] In one embodiment, the exhaust assembly 90 is arranged on the wall portion of the outer shell of the battery cell 20. The outer shell includes an end cover 21 and a shell 22. The wall portion can be the wall of the end cover 21 or the wall of the shell 22. That is, the exhaust assembly 90 can be arranged on the end cover 21 or on the shell 22. In other words, the wall portion for mounting the exhaust assembly 90 can be the end cover 21 of the outer shell or a wall of the shell 22 of the outer shell. Exemplarily, the wall portion is the end cover 21. Of course, the structure of the battery cell is not limited to this. In other embodiments, the wall portion can also be the bottom wall of the shell and the end cover, which are arranged opposite to each other. The wall portion can also be the side wall of the shell and the end cover that are adjacent to and connected to each other. In one embodiment, the exhaust assembly is preferably located on the wall with the top facing up when the battery cell is in a placed state. The following will illustrate the present application scheme by taking the wall portion as the wall of the end cover 21 as an example, but this should not limit the present application.

[0214] Please refer to Figures 5, 6, and 7. Figure 5 is a schematic front view of a one-way valve according to one or more embodiments, Figure 6 is a schematic exploded structural view of a one-way valve according to one or more embodiments, and Figure 7 is a schematic partial cross-sectional view of a battery cell according to one or more embodiments. According to some embodiments of the present application, the end cap 21 includes an outer surface 21a and an inner surface 21b disposed opposite each other, with the outer surface 21a facing the exterior of the housing and the inner surface 21b facing the interior of the housing. The one-way valve 30 is disposed on the end cap 21, with the valve body 31 of the one-way valve 30 facing the exterior of the housing and at least a portion of the valve body 31 protruding from the outer surface 21a of the end cap 21.

[0215] In this embodiment, the one-way valve 30 includes a valve body 31 and a valve core 32. The valve body 31 defines a valve cavity 313, and the valve core 32 is disposed within the valve cavity 313. The valve body 31 includes a valve seat 311 and a valve cover 312. The valve cover 312 includes a cover top wall 3121 and a cover side wall 3122 connected to the cover top wall 3121. The cover top wall 3121, the cover side wall 3122, and the valve seat 311 enclose a valve cavity 313. The valve seat 311 is provided with an air inlet for the valve cavity 313, connecting the valve cavity 313 with the interior of the housing. The valve cover 312 is provided with an air outlet for the valve cavity 313, connecting the valve cavity 313 with the exterior of the housing. The valve core 32 is used to block the air inlet channel of the valve cavity 313. The valve core 32 is configured to open the air inlet channel in response to gas inside the housing, thereby releasing gas from the battery cells.

[0216] Continuing with Figures 5 and 6 , according to some embodiments of the present application, the valve seat 311 has a first through-hole 3111 extending through the valve seat 311. The first through-hole 3111 serves as the air inlet for the valve cavity 313. The cover sidewall 3122 has a second through-hole 31221 extending through the cover sidewall 3122. The second through-hole 31221 serves as the air outlet for the valve cavity 313. This arrangement facilitates the outward transmission of gas from within the battery.

[0217] According to some embodiments of the present application, the second through hole 31221 extends to the end of the cover side wall 3122 in a direction away from the cover top wall 3121. As shown in Figure 6, the direction away from the cover top wall 3121 is the direction from the cover top wall 3121 to the valve seat 311 (the X direction in the figure). The second through hole 31221 is formed by removing part of the structure of the cover side wall 3122. Along the X direction, the cover side wall 3122 is directly hollowed out to the bottom end of the cover side wall 3122. In a further embodiment, along the X direction, the lower opening surface of the second through hole 31221 can be flush with the sealing surface of the blocking member 321. Through this arrangement, when the one-way valve 30 is opened to exhaust, that is, when the blocking member 321 opens the sealing interface, the electrolyte liquid carried out with the gas can be discharged outward in a timely manner, so that the electrolyte is not easily accumulated on the outer edge of the blocking member 321, thereby effectively ensuring the sealing and repeated opening function of the one-way valve 30.

[0218] According to some embodiments of the present application, there are multiple second through holes 31221, and the multiple second through holes 31221 are spaced apart in the circumferential direction of the cover side wall 3122. This arrangement allows for faster exhaust of gas when the one-way valve 30 is opened for exhaust, shortening the exhaust time, that is, shortening the time the battery cell is in the open state, thereby reducing the intrusion of external moisture into the battery system during the valve opening period.

[0219] Please refer to Figures 8, 9 and 10. Figure 8 is a front view of a one-way valve according to one or more embodiments, and Figure 9 is a schematic diagram of the exploded structure of a one-way valve according to one or more embodiments. Figure 10 is a schematic diagram of the partial cross-sectional structure of a battery cell according to one or more embodiments. According to some embodiments of the present application, the end cover 21 includes an outer surface 21a and an inner surface 21b arranged in opposite directions, the outer surface 21a is arranged toward the outside of the shell, and the inner surface 21b is arranged toward the inside of the shell; the one-way valve 30 is arranged on the end cover 21, and the valve body 31 of the one-way valve 30 faces the inside of the shell and at least a portion of the valve body 31 protrudes from the inner surface 21b of the end cover 21. That is, the valve body 31 extends into the shell along the thickness direction of the end cover 21.

[0220] In this embodiment, the one-way valve 30 includes a valve body 31 and a valve core 32. The valve body 31 defines a valve cavity 313, and the valve core 32 is disposed within the valve cavity 313. The valve body 31 includes a valve seat 311 and a valve cover 312. The valve seat 311 includes a seat bottom wall 3115 and a seat sidewall 3116 connected to the seat bottom wall 3115. The valve cover 312 is disposed at one end of the valve seat 311 away from the seat bottom wall 3115. The valve cover 312, the seat sidewall 3116, and the seat bottom wall 3115 enclose the valve cavity 313. The valve seat 311 is provided with an air inlet for the valve cavity 313, connecting the valve cavity 313 with the interior of the housing. The valve core 32 is used to block the air inlet passage of the valve cavity 313. The valve core 32 is configured to open the air inlet passage in response to gas within the housing, thereby releasing gas from the battery cells.

[0221] Continuing with reference to Figures 8, 9, and 10, according to some embodiments of the present application, the valve seat 311 has a fourth through hole 3114 extending through the bottom wall 3115 of the seat, and the air inlet is the fourth through hole 3114, that is, the fourth through hole 3114 serves as the air inlet of the valve cavity 313. Of course, in other embodiments, the air inlet can also be provided on the outer circumferential surface of the portion of the valve seat 311 extending into the housing. When the air inlet is provided on the outer circumferential surface of the portion of the valve seat 311 extending into the housing, the setting direction of the valve core 32 will be changed accordingly, and the blocking member 321 is movably provided in the valve cavity 313 along the radial direction of the valve seat 311, so that the valve core blocks the air inlet.

[0222] Continuing with Figures 8, 9, and 10, according to some embodiments of the present application, the gas outlet can be directly provided on the valve cover, i.e., the gas outlet is a channel provided on the valve cover. Specifically, the valve cover 312 has a fifth through hole 3123 extending therethrough, and the gas outlet is the fifth through hole 3123, i.e., the fifth through hole 3123 serves as the gas outlet of the valve cavity 313. This arrangement facilitates the outward transmission of gas from within the battery cell.

[0223] The fifth through hole 3123 provided on the valve cover 312 can be one or more. For example, in Figures 8 and 9, the valve cover 312 is provided with three fifth through holes 3123. Of course, in other embodiments, the valve cover 312 can also be provided with two, four, five, or six fifth through holes 3123. By way of example, the valve cover 312 is provided with multiple fifth through holes 3123, and the multiple fifth through holes 3123 are arranged at equal intervals. By way of example, the multiple fifth through holes 3123 are arranged at equal intervals around the center of the valve cover 312, which allows for smoother gas flow.

[0224] Please refer to Figure 11, which is a schematic cross-sectional view of a breathable membrane assembly according to one or more embodiments. According to some embodiments of the present application, the breathable membrane assembly 40 includes a breathable membrane 41 and a connector 42, which is used to support the breathable membrane 41. The connector 42 is provided with a first vent 491, and the breathable membrane 41 is disposed on the connector 42, covering the first vent 491. The breathable membrane is configured to allow gas within the battery cell to pass through the breathable membrane and be discharged.

[0225] The connector 42 can support the breathable membrane 41 and reduce the risk of excessive deformation of the breathable membrane 41. At the same time, the connector 42 can also serve as a medium for connecting other components of the breathable membrane assembly 40. The breathable membrane 41 is connected to other components through the connector 42 to improve the stability of the connection. The connector 42 is provided with at least one first air hole 491, which serves as a release channel for the gas inside the battery cell so that the gas can pass through the connector 42. The shape of the first air hole 491 includes geometric shapes such as circle, square, and ellipse. The connector 42 can also be provided with multiple first air holes 491. The aperture, shape, and arrangement of the first air holes 491 are not specifically limited here. In one embodiment, the aperture of the first air hole 491 may be less than or equal to the aperture of the exhaust hole on the battery cell.

[0226] In one embodiment, connector 42 may be a metal member, a resin member, or the like. The metal member may be made of copper, iron, aluminum, steel, or an aluminum alloy. Selecting a metal connector 42 facilitates welding of the connector 42 to the wall. The following description of this application utilizes a metal connector 42 as an example, but this is not intended to limit this embodiment and should not restrict this application. The present invention is also applicable to connectors made of non-metallic materials.

[0227] As shown in FIG11( a ), the breathable membrane 41 can be directly disposed on the surface of the metal member 42 . In other embodiments, a sink can also be disposed on the metal member 42 .

[0228] Referring to FIG. 11( b ), according to some embodiments of the present application, the metal member 42 has a first annular platform T1 that is recessed relative to the surface of the metal member 42 . The first annular platform T1 is disposed around the first vent 491 , and the breathable membrane 41 is disposed on the first annular platform T1 . This arrangement can reduce the installation height of the breathable membrane assembly 40 .

[0229] According to some embodiments of the present application, the breathable membrane assembly 40 further includes a backing member 43 , which is disposed between the breathable membrane 41 and the metal member 42 . The air permeability of the backing member 43 is greater than that of the breathable membrane 41 .

[0230] The breathable membrane assembly 40 includes a breathable membrane 41, a metal part 42 and a backing part 43. The breathable membrane 41 is arranged on the metal part 42, and the backing part 43 is arranged between the breathable membrane 41 and the metal part 42. The backing part 43 is used to support the breathable membrane 41 and allow gas to pass through the breathable membrane 41.

[0231] Backing member 43 supports the breathable membrane 41, reducing the risk of deformation. Backing member 43 is made of a material with better air permeability than the breathable membrane 41 to ensure it does not interfere with the ventilation process of the breathable membrane 41. Backing member 43 is also corrosion-resistant and heat-resistant. The material options for backing member 43 are diverse, including porous polymers such as polypropylene, polyamide, polytetrafluoroethylene, and polyperfluoroethylene propylene. Porous metal organic frameworks, carbon membranes, and ceramics are also possible, but are not limited here.

[0232] As shown in Figure 11(c), the metal component 42 also has a second annular surface T2 recessed relative to the surface of the metal component 42. This second annular surface T2 surrounds the first air vent 491, and the backing member 43 is mounted on this second annular surface T2. The second annular surface T2 supports the backing member 43, while the breathable membrane 41 can be directly attached to the surface of the metal component 42. In this configuration, due to the relatively small thickness of the breathable membrane 41, the overall height of the breathable membrane assembly 40 is relatively minimal. By reducing the number of recessed surfaces on the metal component 42, the manufacturing process is simplified while also improving the strength of the metal component 42.

[0233] As shown in (d) of Figure 11, the metal part 42 has a first annular table T1 and a second annular table T2 that are recessed relative to the surface of the metal part 42, and a transition surface T3. The first annular table T1 is arranged around the second annular table T2, and the transition surface T3 connects the first annular table T1 and the second annular table T2. The first annular table T1 is closer to the surface of the metal part 42 than the second annular table T2. The second annular table T2 is arranged around the first air hole 491. The backing member 43 is arranged on the second annular table T2, and the breathable membrane 41 is arranged on the first annular table T1.

[0234] The first annular table T1 and the second annular table T2 are formed by inward depressions on the surface of the metal member 42. This can be achieved by stamping the metal member 42 to form the inward depressions, or by etching the metal member 42 to remove portions of the structure. The depth of the depressions of the first annular table T1 and the second annular table T2 relative to the surface of the metal member 42 can be set based on the thickness of the breathable membrane 41 and the backing member 43. In one embodiment, the depth of the depression of the second annular table T2 relative to the first annular table T1 (i.e., the height of the transition surface T3) is equal to the thickness of the backing member 43, so that the second annular table can accommodate the backing member 43, and the surface of the backing member 43 facing the breathable membrane 41 is flush with the first annular table T1. Furthermore, the depression depth of the first annular platform T1 relative to the surface of the metal component 42 is equal to the thickness of the breathable membrane 41 , so that the first annular platform can accommodate the breathable membrane 41 , and the side surface of the breathable membrane 41 away from the metal component 42 is flush with the surface of the metal component 42 .

[0235] By providing a recessed platform on the metal member 42 , the surface of the breathable membrane 41 can be flush with the surface of the metal member 42 , thereby reducing the overall height of the breathable membrane assembly 40 and further reducing the installation height of the breathable membrane assembly 40 .

[0236] Please refer to Figures 12, 13, and 14. Figure 12 is a partial cross-sectional view of an end cap according to one or more embodiments; Figure 13 is a partial cross-sectional view of a battery cell according to one or more embodiments; and Figure 14 is a partial front view of a battery cell according to one or more embodiments.

[0237] According to some embodiments of the present application, the one-way valve 30 is arranged on the end cover 21, the valve body 31 of the one-way valve 30 faces the outside of the shell and at least part of the valve body 31 protrudes from the outer surface 21a of the end cover 21, and the breathable membrane assembly 40 is arranged on the side of the end cover 21 facing the inside of the shell; the one-way valve 30 and the breathable membrane assembly 40 are respectively and independently connected to the end cover 21.

[0238] According to some embodiments of the present application, the end cap 21 is provided with a first vent 291. The first vent 291 includes a through-hole section 280 and a first hole section 281. The through-hole section 280 and the first hole section 281 are arranged along the thickness direction of the end cap 21. The through-hole section 280 connects the interior of the housing with the exterior of the housing. The first hole section 281 is located on the side of the through-hole section 280 facing away from the interior of the housing. The aperture of the first hole section 281 is larger than the aperture of the through-hole section 280. The one-way valve 30 is at least partially accommodated in the first hole section 281. The valve body 31 of the one-way valve 30 faces the exterior of the housing, and at least a portion of the valve body 31 protrudes from the outer surface 21a of the end cap 21. As shown in FIG. 12 , the first vent 291 is a countersunk hole that is recessed relative to the outer surface 21a of the end cap 21. When the one-way valve 30 is connected to the end cap 21, a portion of the one-way valve 30 can be embedded in the first vent 291 to reduce the installation height.

[0239] According to some embodiments of the present application, the one-way valve 30 is welded to the end cap 21. As shown in FIG13 , the valve seat 311 of the one-way valve 30 can be welded to the end cap 21; specifically, the valve cap 312 of the one-way valve 30 is connected to the valve seat 311, and the valve seat 311 is welded to the end cap 21.

[0240] According to some embodiments of the present application, the breathable membrane assembly 40 includes a breathable membrane 41 and a metal member 42. The breathable membrane 41 is disposed on the metal member 42. The breathable membrane assembly 40 is disposed on the end cap 21, and the metal member 42 is connected to the end cap 21. Specifically, the breathable membrane 41 is connected to the end cap 21 via the metal member 42. The metal member 42 can be connected to the end cap 21 by welding, interference fit, or other methods. This method can enhance the connection strength between the breathable membrane assembly 40 and the end cap 21.

[0241] Please continue to refer to Figures 13 and 14. According to some embodiments of the present application, the end cover 21 has an outer surface 21a and an inner surface 21b arranged in opposite directions, the outer surface 21a is arranged toward the outside of the shell, and the inner surface 21b is arranged toward the inside of the shell. The end cover 21 has a first sink S1 that is recessed relative to the inner surface 21b. The first sink S1 is arranged around the first exhaust hole 291, and the breathable membrane assembly 40 is at least partially accommodated in the first sink S1.

[0242] Among them, the first depression S1 is formed by the inner surface 21b of the end cover 21 being recessed in the direction of the outer surface 21a of the end cover 21. The end cover 21 can be stamped to form the recessed first depression S1, or the end cover 21 can be etched to remove part of the structure to form the recessed first depression S1. The recessed depth of the first depression S1 relative to the inner surface 21b of the end cover 21 can be set according to the thickness of the breathable membrane assembly 40. The thickness of the breathable membrane assembly 40 is the overall thickness including the breathable membrane 41, the metal part 42 and the backing part 43. As mentioned above, the breathable membrane 41 and the backing part 43 can be accommodated in the annular platform on the metal part 42 that is recessed relative to the surface of the metal part 42, that is, the overall thickness of the breathable membrane assembly 40 can be equal to the thickness of the metal part 42. In one embodiment, the depth of the first recessed portion S1 relative to the inner surface 21b of the end cap 21 is equal to the thickness of the breathable membrane assembly 40, so that the breathable membrane assembly 40 is accommodated within the first recessed portion S1, and the surface of the breathable membrane assembly 40 facing the interior of the housing is flush with the inner surface 21b of the end cap 21. In this manner, the installation height of the breathable membrane assembly 40 can be reduced, thereby reducing the space occupied by the battery cell 20 interior housing and improving the space utilization inside the housing.

[0243] As shown in Figure 13 , the breathable membrane 41 can be disposed on the side of the metal member 42 facing the interior of the housing; that is, the breathable membrane 41 is below the metal member 42. In other embodiments, the breathable membrane 41 can also be disposed on the side of the metal member 42 facing the exterior of the housing, that is, between the metal member 42 and the end cap 21. This arrangement can reduce erosion of the breathable membrane 41 by the electrolyte system.

[0244] Please refer to Figures 15, 16 and 17. Figure 15 is a schematic diagram of the partial cross-sectional structure of the end cover according to one or more embodiments; Figure 16 is a schematic diagram of the partial cross-sectional structure of the battery cell according to one or more embodiments; Figure 17 is a partial front view of the battery cell according to one or more embodiments.

[0245] According to some embodiments of the present application, the one-way valve 30 is arranged on the end cover 21, the valve body 31 of the one-way valve 30 faces the outside of the shell and at least part of the valve body 31 protrudes from the outer surface 21a of the end cover 21, and the breathable membrane assembly 40 is arranged on the side of the end cover 21 facing the outside of the shell; the one-way valve 30 and the breathable membrane assembly 40 are respectively and independently connected to the end cover 21.

[0246] As previously described, the end cap 21 is provided with a first vent 291, which includes a first hole section 281. The one-way valve 30 is at least partially accommodated in the first hole section 281. The valve body 31 of the one-way valve 30 faces the exterior of the housing, and at least a portion of the valve body 31 protrudes from the outer surface 21a of the end cap 21. In this embodiment, the breathable membrane assembly 40 is disposed on the side of the end cap 21 facing the exterior of the housing. The breathable membrane assembly 40 is at least partially accommodated within the first vent 291, and the breathable membrane assembly 40 is located on the side of the one-way valve 30 facing the end cap 21.

[0247] Specifically, the first exhaust hole 291 also includes a second hole section 282. Along the thickness direction of the end cover 21, the second hole section 282 is located between the through hole section 280 and the first hole section 281. The aperture of the second hole section 282 is smaller than the aperture of the first hole section 281, and the aperture of the second hole section 282 is larger than the aperture of the through hole section 280. The breathable membrane assembly 40 is at least partially accommodated in the second hole section 282.

[0248] According to some embodiments of the present application, a breathable membrane assembly includes a breathable membrane and a connector, wherein the connector is provided with a first breathable hole, and the breathable membrane is disposed on the connector and covers the first breathable hole; the breathable membrane is configured to allow gas inside the battery cell to pass through the breathable membrane and be discharged. The connector can be a sheet-like member or a metal member.

[0249] In one embodiment, the breathable membrane assembly 40 includes a breathable membrane 41 and a metal part 42 . The metal part 42 is provided with a first breathable hole 491 . The breathable membrane 41 is provided on the metal part 42 and covers the first breathable hole 491 . The metal part 42 is welded to the end cover 21 .

[0250] According to some embodiments of the present application, the one-way valve 30 may be disposed on the end cap 21, with the valve body 31 of the one-way valve 30 facing the interior of the housing and at least a portion of the valve body 31 protruding from the inner surface 21b of the end cap 21. The breathable membrane assembly 40 is connected to the one-way valve 30, and the one-way valve 30 is connected to the end cap 21. In other words, the one-way valve 30 and the breathable membrane assembly 40 are first assembled and then connected to the end cap 21.

[0251] Please refer to Figures 18 and 19. Figure 18 is a schematic diagram of the decomposed structure of the exhaust assembly according to one or more embodiments; Figure 19 is a schematic diagram of the cross-sectional structure of the exhaust assembly according to one or more embodiments. According to some embodiments of the present application, the breathable membrane 41 membrane assembly is arranged on the side of the seat bottom wall 3115 of the one-way valve 30 away from the valve cavity 313. The breathable membrane assembly 40 includes a breathable membrane 41, which is connected to the seat bottom wall 3115 and covers the fourth through hole 3114. In this embodiment, the breathable membrane assembly 40 is compounded with the one-way valve 30, and the breathable membrane 41 is attached to the seat bottom wall 3115 of the one-way valve 30, which can reduce the installation height; at the same time, only the one-way valve 30 needs to be connected to the end cover 21, which can simplify the assembly process.

[0252] Please refer to Figures 20 and 21 . Figure 20 is a schematic diagram of the exploded structure of an exhaust assembly according to one or more embodiments; Figure 21 is a schematic diagram of the cross-sectional structure of an exhaust assembly according to one or more embodiments. According to some embodiments of the present application, a breathable membrane assembly 40 is disposed on a side of the seat bottom wall 3115 of the one-way valve 30 away from the valve cavity 313. The breathable membrane assembly 40 includes a breathable membrane 41 and a metal member 42. The metal member 42 is provided with a first breathable hole 491. The breathable membrane 41 is disposed on the metal member 42 and covers the first breathable hole 491. The metal member 42 is connected to the seat bottom wall 3115. In this embodiment, by utilizing the metal member 42 to connect to the seat bottom wall 3115, the connection strength can be improved.

[0253] Referring to Figures 22 and 23 , Figure 22 is an exploded view of an exhaust assembly according to one or more embodiments; Figure 23 is a cross-sectional view of an exhaust assembly according to one or more embodiments. According to some embodiments of the present application, the breathable membrane assembly 40 is disposed on the side of the seat bottom wall 3115 facing the valve cavity 313.

[0254] The valve chamber 313 includes a first chamber 3131 and a second chamber 3132 that are interconnected. The second chamber 3132 is closer to the seat bottom wall 3115. Along a direction parallel to the seat bottom wall 3115, the cross-sectional area of ​​the first chamber 3131 is larger than that of the second chamber 3132. The valve core 32 is located in the first chamber 3131, and the breathable membrane assembly 40 is located in the second chamber 3132. This arrangement allows gas to enter the valve chamber and first pass through the breathable membrane assembly before reaching the valve core, thereby preventing electrolyte from overflowing.

[0255] Furthermore, the seat sidewall 3116 includes a first sidewall portion 3116a, a second sidewall portion 3116b, and a third sidewall portion 3116c. The first sidewall portion 3116a and the second sidewall portion 3116b enclose a first cavity 3131. The third sidewall portion 3116c and the seat bottom wall 3115 enclose the first cavity 3131. The blocking member 321 of the valve core 32 abuts the second sidewall portion 3116b. In this embodiment, the second cavity 3132 is open to communicate with the first cavity 3131. The blocking member 321 of the valve core 32 located in the first cavity 3131 abuts the second sidewall portion 3116b, allowing the blocking member 321 to block the second cavity 3132. When the internal air pressure of the battery cell is low, the gas cannot enter the first cavity 3131 from the second cavity 3132 . When the internal air pressure of the battery cell is high, the gas enters the second cavity 3132 , pushes open the sealing member 321 , enters the first cavity 3131 , and is then discharged from the gas outlet of the valve cavity 313 .

[0256] 23 , according to some embodiments of the present application, the breathable membrane assembly 40 is located in the second cavity 3132 , so that gas passes through the breathable membrane assembly 40 before being discharged from the first cavity 3131 through the second cavity 3132 .

[0257] In which, the breathable membrane assembly 40 can only include a breathable membrane 41, which is attached to the side of the seat bottom wall 3115 facing the valve cavity 313 and covers the fourth through hole 3114. In this case, the gas entering from the fourth through hole 3114 passes through the breathable membrane 41, blocking the electrolyte from entering the second cavity 3132.

[0258] In another embodiment, the breathable membrane assembly 40 may include a breathable membrane 41 and a metal part 42, and the breathable membrane 41 is arranged on the metal part 42. The metal part 42 is connected to the wall of the second cavity 3132 (the third side wall portion 3116c), which can improve the stability of the connection and prevent the breathable membrane 41 from being displaced by the gas top.

[0259] The breathable membrane 41 can be disposed on the side of the metal member 42 facing the seat bottom wall 3115, so that the metal member 42 provides support for the breathable membrane 41 and prevents the breathable membrane 41 from being displaced by the gas. In other embodiments, the breathable membrane 41 can also be disposed on the side of the metal member 42 away from the seat bottom wall 3115.

[0260] Please continue to refer to Figure 23. According to some embodiments of the present application, when the breathable membrane 41 is arranged on the side of the metal part 42 facing the seat bottom wall 3115, the surface of the side of the metal part 42 away from the breathable membrane 41 is lower than the surface of the second side wall portion 3116b. Through this arrangement, a certain cavity can be created between the metal part 42 and the sealing part 321, which is conducive to the discharge of gas.

[0261] 23 , according to some embodiments of the present application, the battery cell 20 further includes a sealing ring 80 disposed between the breathable membrane assembly 40 and the seat bottom wall 3115. This arrangement can improve the sealing between the breathable membrane assembly 40 and the seat bottom wall 3115.

[0262] Furthermore, a sealing ring 80 is disposed between the breathable membrane 41 and the seat bottom wall 3115. The sealing ring 80 is disposed around the fourth through hole 3114 and is provided with a second breathable hole 801. The aperture of the second breathable hole 801 is larger than the aperture of the fourth through hole 3114. The breathable membrane 41 covers the second breathable hole 801. This arrangement improves the sealing between the breathable membrane 41 and the seat bottom wall 3115, and the sealing ring 80 does not block the flow of gas.

[0263] According to some embodiments of the present application, the metal member 42 is welded to the third side wall portion 3116 c ; or the metal member 42 is interference fit to the third side wall portion 3116 c .

[0264] According to some embodiments of the present application, a battery 100 is provided, comprising a battery cell 20 according to any of the above-described embodiments. Please refer to FIG. 24 , which is a schematic diagram of an exploded structure of a battery according to one or more embodiments. The battery 100 comprises a housing 10 and a battery cell 20, with the battery cell 20 contained within the housing 10. The housing 10 is configured to provide a storage space for the battery cell 20 and can have various structures. In some embodiments, the housing 10 can include a first portion 11 and a second portion 12, which overlap with each other and together define a storage space for the battery cell 20. The second portion 12 can be a hollow structure with one end open, and the first portion 11 can be a plate-like structure, overlapping the open side of the second portion 12, so that the first portion 11 and the second portion 12 together define a storage space. Alternatively, the first portion 11 and the second portion 12 can each be a hollow structure with one end open, with the open side of the first portion 11 overlapping the open side of the second portion 12. Of course, the box body 10 formed by the first part 11 and the second part 12 can be in various shapes, such as a cylinder, a cuboid, etc.

[0265] In the battery 100, there may be multiple battery cells 20, and the multiple battery cells 20 may be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 may be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 20 may be housed within the housing 10. Alternatively, the battery 100 may be constructed by first connecting multiple battery cells 20 in series, in parallel, or in a hybrid connection to form a battery module, which is then connected in series, in parallel, or in a hybrid connection to form a complete battery module, and then housed within the housing 10. The battery 100 may also include other structures, such as a busbar assembly for electrically connecting the multiple battery cells 20.

[0266] Each battery cell 20 may be a secondary battery or a primary battery; specific examples include all types of primary or secondary batteries. For example, it may be a lithium battery, a sodium battery, a potassium battery, or other different types of secondary batteries. Lithium secondary batteries may include lithium metal secondary batteries, lithium ion secondary batteries, lithium polymer secondary batteries, or lithium ion polymer secondary batteries. Other types may include, but are not limited to, lithium sulfur batteries, sodium ion batteries, or magnesium ion batteries. Battery cells 20 may be cylindrical, flat, rectangular, or other shapes.

[0267] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0268] According to some embodiments of the present application, the present application further provides an electric device, which includes a battery cell according to any of the above solutions, and the battery cell is used to provide power to the electric device. The electric device can be any of the above devices or systems using the battery cell.

[0269] In some embodiments, the purposes of the electric equipment of the present application are not particularly limited, and it can be used for any electronic device known in the prior art. The battery disclosed in the embodiment of the present application can be used for electric equipment using a battery as a power source or various energy storage systems using a battery as an energy storage element. That is, a kind of electric equipment is provided. In some embodiments, the electric equipment of the present application can be used for, but not limited to, a laptop computer, a pen-input type computer, a mobile computer, an e-book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, an LCD TV, a portable cleaner, a portable CD player, a mini disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, a power-assisted bicycle, a bicycle, a ship, a spacecraft, a lighting fixture, a toy, a game console, a clock, an electric tool, a flashlight, a camera, a large-scale battery for household use and a lithium-ion capacitor etc.

[0270] Electrical equipment can choose battery cells, battery modules or battery packs according to its usage requirements.

[0271] Please refer to Figure 25, which is a schematic structural diagram of a vehicle according to one or more embodiments. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can serve as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0272] In some embodiments of the present application, the battery 100 can serve not only as an operating power source for the vehicle 1000, but also as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0273] The above description is only an implementation method of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the description and drawings of this application, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A battery cell, wherein: include: a housing having a wall portion and a receiving cavity; an exhaust assembly, disposed on the wall portion, and configured to exhaust gas from inside the housing; An electrode assembly is accommodated in the accommodating cavity, wherein the electrode assembly includes a negative electrode plate, the negative electrode plate includes a negative electrode current collector and a carbon-containing coating arranged on one side surface of the negative electrode current collector, and the thickness of the carbon-containing coating is 1 μm≤L≤15 μm.

2. The battery cell according to claim 1, wherein: The thickness of the carbon-containing coating is 1 μm≤L≤8 μm.

3. The battery cell according to claim 1 or 2, wherein: Based on the total mass of the carbon-containing coating, the carbon content in the carbon-containing coating is 5%-50%.

4. The battery cell according to any one of claims 1 to 3, wherein: The water content of the negative electrode plate is 100ppm-600ppm.

5. The battery cell according to any one of claims 1 to 4, wherein: The electrode assembly also includes a positive electrode plate, which includes a positive electrode active material. Based on the total mass of the positive electrode active material, the residual alkali content in the positive electrode active material is 0% wt<residual alkali content≤0.5% wt, and the residual alkali includes one or more of oxides, hydroxides, carbonates, and nitrates of active ions.

6. The battery cell according to any one of claims 1 to 5, wherein: The electrode assembly further comprises a positive electrode sheet, wherein the positive electrode sheet comprises a positive electrode active material, and the specific surface area of ​​the positive electrode active material is 2m 2 / g<Specific surface area≤7m 2 / g.

7. The battery cell according to any one of claims 1 to 6, wherein: The electrode assembly further includes a positive electrode sheet, which includes a positive electrode active material. Based on the total mass of the positive electrode active material, the carbon content of the positive electrode active material is 0.5%<carbon content≤1.5%.

8. The battery cell according to any one of claims 1 to 7, wherein: The electrode assembly further includes a positive electrode plate, and the water content of the positive electrode plate is 50ppm-400ppm.

9. The battery cell according to any one of claims 1 to 8, wherein: The battery cell further includes an electrolyte, which is filled in the accommodation cavity. The conductivity of the electrolyte is 0.5 ms / cm≤conductivity≤5 ms / cm.

10. The battery cell according to any one of claims 1 to 9, wherein: The exhaust assembly includes a breathable membrane assembly, the breathable membrane assembly includes a breathable membrane, and the breathable membrane has a breathability rate of 2.0-10.0 mL / day.

11. The battery cell according to claim 10, wherein: The film thickness of the breathable film is 20 μm ≤ film thickness ≤ 100 μm.

12. The battery cell according to claim 10 or 11, wherein: The ratio of the air permeable area of ​​the air permeable membrane to the area of ​​the wall where the air permeable membrane assembly is located is 5%-10%.

13. The battery cell according to any one of claims 10 to 12, wherein: The exhaust assembly includes the breathable membrane assembly and a one-way valve, the wall portion has a first exhaust hole, the first exhaust hole connects the inside of the shell with the outside of the shell, and the battery cell is configured so that the gas exhausted through the first exhaust hole flows through the one-way valve and the breathable membrane assembly.

14. The battery cell according to claim 13, wherein: The opening pressure of the one-way valve is greater than or equal to 0.4 MPa.

15. The battery cell according to any one of claims 10 to 12, wherein: The exhaust assembly includes the breathable membrane assembly and a one-way valve, the wall portion has a first exhaust hole and a second exhaust hole arranged at intervals, the first exhaust hole and the second exhaust hole respectively connect the inside of the shell and the outside of the shell, and the battery cell is configured so that the gas exhausted through the first exhaust hole flows through the one-way valve, and the gas exhausted through the second exhaust hole passes through the breathable membrane assembly.

16. The battery cell according to claim 15, wherein: The opening pressure of the one-way valve is greater than or equal to 0.5 MPa.

17. The battery cell according to claim 1, wherein The thickness of the carbon-containing coating is 8 μm <L≤15μm。 18. The battery cell according to claim 1 or 17, wherein: Based on the total mass of the carbon-containing coating, the carbon content in the carbon-containing coating is 50%-90%.

19. The battery cell according to any one of claims 1, 17-18, wherein: The water content of the negative electrode plate is 600ppm-1200ppm.

20. The battery cell according to any one of claims 1, 17-19, wherein: The electrode assembly also includes a positive electrode plate, which includes a positive electrode active material. Based on the total mass of the positive electrode active material, the residual alkali content in the positive electrode active material is 0.5%wt<residual alkali content≤1.5%wt, and the residual alkali includes one or more of oxides, hydroxides, carbonates, and nitrates of active ions.

21. The battery cell according to any one of claims 1, 17-20, wherein: The electrode assembly further comprises a positive electrode sheet, wherein the positive electrode sheet comprises a positive electrode active material, and the specific surface area of ​​the positive electrode active material is 7m 2 / g<Specific surface area≤15m 2 / g.

22. The battery cell according to any one of claims 1, 17-21, wherein: The electrode assembly further includes a positive electrode sheet, which includes a positive electrode active material. Based on the total mass of the positive electrode active material, the carbon content of the positive electrode active material is 1.5%<carbon content≤2.5%.

23. The battery cell according to any one of claims 1, 17-22, wherein: The electrode assembly further includes a positive electrode plate, and the water content of the positive electrode plate is 400ppm-1000ppm.

24. The battery cell according to any one of claims 1, 17-23, wherein: The battery cell further includes an electrolyte, which is filled in the accommodation cavity. The conductivity of the electrolyte is 5 ms / cm≤conductivity≤15 ms / cm.

25. The battery cell according to claim 24, wherein The electrolyte includes a first component, which includes one or a mixture of two or more of dimethyl carbonate, 2-methyltetrahydrofuran, diethylene glycol dimethyl ether, diethylene glycol dimethyl ether, succinonitrile, glutaronitrile, methyl formate, ethyl formate, methyl acetate, ethyl acetate, methyl acrylate, dimethyl sulfite, diethyl sulfite, methyl ethyl sulfite, 3-methyl-2-butanone, and 3-methyl-2-butanone.

26. The battery cell according to claim 25, wherein: Based on the total mass of the electrolyte, the content of the first component is 5%-85%.

27. The battery cell according to any one of claims 17 to 26, wherein: The exhaust assembly includes a one-way valve, and the opening pressure of the one-way valve is 0.3MPa-0.5MPa.

28. The battery cell according to claim 27, wherein: The exhaust assembly includes the one-way valve and the breathable membrane assembly, the wall portion has a first exhaust hole, the first exhaust hole connects the inside of the shell and the outside of the shell, and the battery cell is configured so that the gas exhausted through the first exhaust hole flows through the one-way valve and the breathable membrane assembly.

29. The battery cell according to claim 27, wherein: The exhaust assembly includes the one-way valve and the breathable membrane assembly, the wall portion has a first exhaust hole and a second exhaust hole arranged at intervals, the first exhaust hole and the second exhaust hole respectively connect the inside of the shell and the outside of the shell, and the battery cell is configured so that the gas exhausted through the first exhaust hole flows through the one-way valve, and the gas exhausted through the second exhaust hole flows through the breathable membrane assembly.

30. The battery cell according to claim 27 or 29, wherein: The air permeability of the breathable membrane meets the requirements of greater than 0 and less than or equal to 15mL / D, and the water permeability meets the requirements of 10 -4 MPa.

31. The battery cell according to any one of claims 1 to 30, wherein: The electrode assembly includes a positive electrode plate, the positive electrode plate includes a positive electrode active material, the positive electrode active material includes a first type of material, the first type of material includes a first ternary material, and the mass content of nickel in the first ternary material is 50%≤nickel content<100%.

32. The battery cell according to claim 31, wherein The median particle size Dv50 of the first ternary material is 2-4 μm.

33. The battery cell according to claim 31 or 32, wherein: The mass content of cobalt in the first ternary material is 12%-18%.

34. The battery cell according to any one of claims 31 to 33, wherein: Based on the total mass of the positive electrode active material, the content of the first ternary material is greater than or equal to 50%.

35. The battery cell according to any one of claims 31 to 34, wherein: The first ternary material includes one or more of single crystal particles and polycrystalline particles.

36. The battery cell according to any one of claims 1 to 35, wherein: The battery cells include alkali metal battery cells.

37. The battery cell according to any one of claims 1 to 36, wherein: The carbon-containing coating comprises a carbon-containing material, and the carbon-containing material comprises one or more of conductive carbon, graphite, hard carbon, and carbon nanotubes.

38. The battery cell according to claim 13 or 28, wherein: The wall portion has an outer surface and an inner surface arranged in opposite directions, the outer surface is arranged toward the outside of the shell, and the inner surface is arranged toward the inside of the shell. The first exhaust hole includes a through hole segment and a first hole segment. The through hole segment and the first hole segment are arranged along the thickness direction of the wall portion. The first hole segment is located on the side of the through hole segment away from the inside of the shell. The aperture of the first hole segment is larger than the aperture of the through hole segment. The one-way valve covers the first exhaust hole.

39. The battery cell according to claim 38, wherein: At least part of the valve body of the one-way valve protrudes from the outer surface; the wall portion has a first sinking platform that is recessed relative to the inner surface, the first sinking platform surrounds the through hole section of the first exhaust hole, and the breathable membrane assembly is at least partially accommodated in the first sinking platform.

40. The battery cell according to claim 38, wherein At least part of the valve body of the one-way valve protrudes from the outer surface; the first exhaust hole also includes a second hole section, along the thickness direction of the wall portion, the second hole section is located between the through hole section and the first hole section, the aperture of the second hole section is smaller than the aperture of the first hole section, the aperture of the second hole section is larger than the aperture of the through hole section, the breathable membrane assembly is at least partially accommodated in the second hole section, and the breathable membrane assembly is located on the side of the one-way valve facing the wall portion.

41. The battery cell according to claim 38, wherein The one-way valve includes a valve body, at least part of which protrudes from the inner surface of the wall portion, and the valve body includes a valve seat and a valve cover, wherein the valve seat includes a seat bottom wall and a seat side wall connected to the seat bottom wall; the valve cover is arranged at one end of the valve seat away from the seat bottom wall, and the valve cover, the seat side wall, and the seat bottom wall enclose a valve cavity, and the valve seat is provided with an air inlet of the valve cavity; wherein, The breathable membrane assembly is arranged on a side of the seat bottom wall away from the valve cavity; or The breathable membrane assembly is arranged on a side of the seat bottom wall facing the valve cavity.

42. The battery cell according to any one of claims 13 to 16 and 27 to 29, wherein: The one-way valve includes a valve body and a valve core, the valve body has a valve cavity inside, the valve body is provided with an air inlet and an air outlet, the air inlet is used to connect the valve cavity with the interior of the shell, and the air outlet is used to connect the valve cavity with the outside of the shell; the valve core is arranged in the valve cavity, the valve core is used to block the air inlet channel of the valve cavity, and the valve core is configured to open the air inlet channel under the action of the gas inside the shell.

43. The battery cell according to any one of claims 10-16, 27-29, wherein: The breathable membrane assembly includes a breathable membrane and a connector, wherein the connector is provided with a first breathable hole, and the breathable membrane is provided on the connector and covers the first breathable hole; the breathable membrane is configured to allow gas inside the battery cell to pass through the breathable membrane and be discharged.

44. A battery, wherein Comprising the battery cell according to any one of claims 1-43.

45. An electrical device, wherein: The battery cell comprises the battery cell according to any one of claims 1 to 43, wherein the battery cell is used to provide electrical energy.

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