Battery cell, battery and electric device

Abstract

A battery cell (20), a battery (100), and an electric device. The battery cell (20) comprises a shell (22), a venting assembly (90) and an electrolyte solution, wherein the venting assembly (90) is arranged on a wall and used for discharging gas from the shell (22); an accommodating cavity (221) is filled with the electrolyte solution; and the electrolyte solution comprises a first component, the first component comprising one of or a mixture of two or more of dimethyl carbonate, 2-methyltetrahydrofuran, diethylene glycol dimethyl ether, succinonitrile, glutaronitrile, methyl formate, ethyl formate, methyl acetate, ethyl acetate, methyl acrylate, dimethyl sulfite, diethyl sulfite, ethyl methyl sulfite and 3-methyl-2-butanone. By means of such configurations, a balance between a high battery performance requirement and a high gas production amount can be achieved.

Description

Battery cells, batteries and electrical equipment Technical Field

[0001] 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

[0002] As global energy and environmental issues continue to intensify, new energy sources are rapidly developing as a sustainable development area. Batteries are becoming increasingly widely used as a new energy source, and high standards are being placed on their safety and service life. During the charge and discharge process, the generation of gas inside the battery cells can cause the internal pressure of the battery cells to increase, reducing their safety and shortening their service life. The above statements are intended only to provide background information related to this application and do not necessarily constitute prior art.

[0003] Summary of the Invention

[0004] 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 cell and greatly increase the life of the battery cell.

[0005] To solve the above technical problems, the present application adopts a technical solution: providing a battery cell, the battery cell comprising a housing, a vent assembly, and an electrolyte, wherein the vent assembly is arranged on the wall and is used to discharge gas inside the housing; the electrolyte is filled in the accommodating cavity; the electrolyte comprises a first component, the first component comprising 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. Through this arrangement, the contradiction between high battery performance requirements and high gas production can be balanced, and the battery cell's charging capacity and energy density can be improved while taking into account the safety performance and service life of the battery cell.

[0006] 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.

[0007] In one embodiment, the content of the first component is 15%-35%. This configuration can balance the contradiction between high performance requirements and high gas production.

[0008] In one embodiment, the content of the first component is 65%-85% based on the total mass of the electrolyte. This configuration 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.

[0009] In one embodiment, the battery cell further comprises an electrode assembly, which is housed within the housing cavity. The electrode assembly comprises a negative electrode plate, which comprises a negative electrode active material, which comprises a silicon-based material. This arrangement improves the energy density of the battery cell while also ensuring safety and longevity.

[0010] In one embodiment, the silicon content is less than or equal to 5% based on the total weight of the negative electrode active material, and the electrolyte further includes fluoroethylene carbonate, with the fluoroethylene carbonate content being less than or equal to 3% based on the total weight of the electrolyte. This configuration suppresses silicon negative electrode expansion, improves battery cell performance, and allows for timely discharge of gas from the battery cells.

[0011] In one embodiment, the silicon content is greater than 5% based on the total weight of the negative electrode active material, and the electrolyte further includes fluoroethylene carbonate, with the fluoroethylene carbonate content exceeding 3% based on the total weight of the electrolyte. This configuration suppresses silicon negative electrode expansion, improving the energy density of the battery cells while also ensuring safety and longevity.

[0012] In one embodiment, the battery cell further includes an electrode assembly, which is accommodated in the accommodating cavity. The electrode assembly includes a positive electrode sheet, 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 improving the energy density of the battery cell.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] In one embodiment, the positive electrode active material further comprises lithium manganese iron phosphate material. This configuration can increase capacity and reduce costs.

[0018] In one embodiment, the thickness of the positive electrode active material is greater than or equal to 130 μm, which can increase the load of the electrode and the energy density of the battery.

[0019] In one embodiment, the exhaust assembly includes a breathable membrane assembly, which includes a breathable membrane having a permeability rate of 0.025-8 mL / day, thereby enabling timely exhaust of gas from the battery cell while preventing external impurities (air, moisture, dust, etc.) from entering the battery cell.

[0020] In one embodiment, a 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 can improve the connection strength of the breathable membrane assembly and reduce the risk of deformation of the breathable membrane.

[0021] In one embodiment, the exhaust assembly includes a one-way valve having an opening pressure greater than or equal to 0.2 MPa; alternatively, greater than or equal to 0.4 MPa; and alternatively, greater than or equal to 0.8 MPa. By adjusting the opening pressure, the valve can be adapted to different application scenarios and different exhaust requirements.

[0022] 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 case, 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.

[0023] 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 wall portion is provided with a first vent hole, the first vent hole comprising a through hole segment and a first hole segment, the through hole segment and the first hole segment being arranged along the thickness direction of the wall portion, the through hole segment communicating the interior of the housing with the exterior of the housing, the first hole segment being located on a side of the through hole segment facing away from the interior of the housing, the aperture of the first hole segment being larger than the aperture of the through hole segment, and the one-way valve being at least partially accommodated in the first hole segment, thereby facilitating assembly of the one-way valve.

[0024] In one embodiment, at least a portion of the valve body of the one-way valve protrudes from the outer surface; the wall portion has a first recessed portion that is recessed relative to the inner surface. The first recessed portion is disposed around the first exhaust hole, and the breathable membrane assembly is at least partially accommodated within the first recessed portion. This can reduce the installation height of the exhaust assembly.

[0025] In one embodiment, at least a portion of the valve body of the one-way valve protrudes from the outer surface of the wall portion. The first vent further includes a second hole segment, which is located between the through-hole segment and the first hole segment along the thickness direction of the wall portion. The second hole segment has 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 in the second hole segment and is located on the side of the one-way valve facing the wall portion. This facilitates assembly of the vent assembly.

[0026] In one embodiment, the 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 can reduce the installation height of the exhaust assembly.

[0027] 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 such 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 case, 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.

[0028] 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 a 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 facilitates the discharge of gas.

[0029] To solve the above technical problems, another technical solution adopted by the present application is to provide a battery comprising the above battery cells, which has at least the same advantages as the battery cells.

[0030] 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.

[0031] 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

[0032] 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.

[0033] FIG1 is a schematic diagram of an exploded structure of a battery cell according to one or more embodiments;

[0034] FIG2 is a schematic diagram of an exploded structure of a battery cell according to one or more embodiments;

[0035] FIG3 is a schematic cross-sectional view of a one-way valve according to one or more embodiments;

[0036] FIG4 is a schematic diagram of a partially exploded structure of a battery cell according to one or more embodiments;

[0037] FIG5 is a front schematic view of a one-way valve according to one or more embodiments;

[0038] FIG6 is a schematic diagram of an exploded structure of a one-way valve according to one or more embodiments;

[0039] FIG7 is a schematic diagram of a partial cross-sectional structure of a battery cell according to one or more embodiments;

[0040] FIG8 is a schematic front view of a one-way valve according to one or more embodiments;

[0041] FIG9 is a schematic diagram of an exploded structure of a one-way valve according to one or more embodiments;

[0042] FIG10 is a schematic diagram of a partial cross-sectional structure of a battery cell according to one or more embodiments;

[0043] FIG11 is a schematic cross-sectional view of a breathable membrane assembly according to one or more embodiments;

[0044] FIG12 is a schematic diagram of a partial cross-sectional structure of an end cap according to one or more embodiments;

[0045] FIG13 is a schematic diagram of a partial cross-sectional structure of a battery cell according to one or more embodiments;

[0046] FIG14 is a partial front view of a battery cell according to one or more embodiments;

[0047] FIG15 is a schematic diagram of a partial cross-sectional structure of an end cap according to one or more embodiments;

[0048] FIG16 is a schematic diagram of a partial cross-sectional structure of a battery cell according to one or more embodiments;

[0049] FIG17 is a partial front view of a battery cell according to one or more embodiments;

[0050] FIG18 is an exploded view of an exhaust assembly according to one or more embodiments;

[0051] FIG19 is a schematic cross-sectional view of an exhaust assembly according to one or more embodiments.

[0052] FIG20 is an exploded structural diagram of an exhaust assembly according to one or more embodiments;

[0053] FIG21 is a schematic cross-sectional view of an exhaust assembly according to one or more embodiments;

[0054] FIG22 is an exploded view of an exhaust assembly according to one or more embodiments;

[0055] FIG23 is a schematic cross-sectional view of an exhaust assembly according to one or more embodiments.

[0056] FIG24 is a schematic diagram of an exploded structure of a battery according to one or more embodiments;

[0057] FIG25 is a schematic structural diagram of a vehicle according to one or more embodiments.

[0058] In the accompanying drawings: 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, insulating member; 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

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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. Optionally, 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 opposite polarity of the electrode assembly 23 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 releasing the internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold value. The material of the end cap 21 may also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not impose any special restrictions on this. In some embodiments, an insulating member 24 may also be provided on the inner side of the end cap 21. The insulating member 24 may be used to isolate the electrical connection components in the housing 22 from the end cap 21 to reduce the risk of short circuit. Exemplarily, the insulating member may be plastic, rubber, etc.

[0071] The housing 22 is a component that cooperates with the end cap 21 to form the internal environment of the battery cell 20. This internal environment can be used to accommodate the electrode assembly 23, electrolyte, and other components. The housing 22 and end cap 21 can be separate components. An opening can be provided in the housing 22, and the end cap 21 is placed over the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 21 and housing 22 can be integrated. Specifically, the end cap 21 and 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 enclosed, the end cap 21 is placed over the housing 22. The housing 22 can have a variety of shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, or a hexagonal prism. Specifically, the shape of the housing 22 can be determined based on the specific shape and size of the electrode assembly 23. The housing 22 can be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this embodiment of the present application does not impose any particular limitations on this.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.).

[0076] In one embodiment, the positive electrode active layer includes a positive electrode active material, and the positive electrode active material may include at least one of the following materials: a lithium-containing phosphate with an olivine structure, a spinel lithium-containing nickel-manganese composite oxide, a lithium transition metal oxide, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and its modified compounds. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. The positive electrode material may also include positive electrode active materials commonly used in sodium metal batteries and potassium metal batteries.

[0077] In one embodiment, the negative electrode sheet includes a negative electrode current collector and a negative electrode active layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode active layer includes a negative electrode active material. In this embodiment, the battery cell is an ion battery. During the charge and discharge process of the battery, active ions (such as Li + ) is embedded / deintercalated in the negative electrode active material.

[0078] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer can be disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0079] 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.).

[0080] The negative electrode active material includes but is not limited to carbon-based negative electrode materials, silicon-based negative electrode materials, tin-based negative electrode materials, lithium titanate negative electrode materials, metallic lithium negative electrode materials, etc.; specifically includes but is not limited to graphite materials, silicon-carbon materials, graphite-silicon oxide materials, nano-silicon materials, silicon oxide materials and tin-based materials; more specifically includes natural graphite, artificial graphite, mesophase microcarbon beads (abbreviated as MCMB), hard carbon, soft carbon, silicon, silicon-carbon composites, Li-Sn alloys, Li-Sn-O alloys, Sn, SnO, SnO2, spinel structured lithiated TiO2-Li4Ti5O 12 , one or more of Li-Al alloys.

[0081] In some embodiments, the positive electrode active layer and the negative electrode active layer may further include a binder, a conductive agent, and other optional additives. As an example, the conductive agent may be one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, Super P (SP), graphene, and carbon nanofibers. As an example, the binder may be one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB). As an example, other optional additives may be thickening and dispersing agents (e.g., sodium carboxymethyl cellulose CMC-Na) and PTC thermistor materials.

[0082] In some embodiments, 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.

[0083] In one embodiment, the electrolyte includes one or more of carbonate solvents and ether solvents.

[0084] Carbonates are generally small molecule cyclic or chain carbonates; including but not limited to one or more of ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, methylpropyl carbonate, dipropyl carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and fluorocarbonates; and may also be at least one ester solvent selected from γ-butyrolactone, dimethyl sulfite, ethyl acetate, methyl acetate, methyl butyrate, ethyl butyrate, methyl propionate, ethyl propionate, propyl acetate, and fluorocarboxylic acid esters.

[0085] Ether solvents include, but are not limited to, one or more of dimethyl ether, diethyl ether, tetrahydrofuran, methyltetrahydrofuran, ethylene oxide, 1,3-dioxolane, fluoroether, DME (ethylene glycol dimethyl ether), DEE (ethylene glycol diethyl ether), DEGDME (diethylene glycol dimethyl ether), TRGDME (triethylene glycol dimethyl ether), TEGDME (tetraethylene glycol dimethyl ether), dipropyl ether and dibutyl ether.

[0086] In other embodiments, the electrolyte may also include any one or a mixture of several of an amine solvent, a sulfone solvent, and a nitrile solvent. The amine solvent includes at least one of N-methylacetamide, N-methylformamide, dimethylformamide, and diethylformamide. The sulfone solvent includes at least one of dimethyl sulfoxide, cyclopentane sulfone, diphenyl sulfoxide, thionyl chloride, and dipropyl sulfone. The nitrile solvent includes at least one of acetonitrile, succinonitrile, adiponitrile, and glutaronitrile. The electrolyte is preferably a high-voltage resistant electrolyte, which has reduced acidity under high voltage, can facilitate the transmission of active ions, significantly reduce side reactions on the electrode surface, and improve battery stability.

[0087] In some embodiments, the electrolyte further includes an electrolyte salt, which can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0088] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain properties of the battery cell, such as additives that improve the overcharge performance of the battery cell, and additives that improve the high or low temperature performance of the battery cell.

[0089] During the charge and discharge process of battery cells, some side reactions generate gases. If the gases generated within the battery cells are not promptly discharged, the internal pressure of the battery cells will increase. Excessive internal pressure can negatively impact the performance and appearance of the battery cells. For example, in severe cases, this can have devastating effects 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, battery cells may be subject to abnormal operation during use, including overcharging, over-discharging, and internal failures. In such cases, the chemical reactions within the battery cells may become uncontrolled, accompanied by a violent release of gases, and even trigger thermal runaway of the battery cells. Thermal runaway of a battery cell 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 to ignite and explode.

[0090] Research has found that the electrolyte is one of the key factors affecting gas production. This is mainly because the electrolyte contains some highly active organic matter, which is prone to oxidation reactions on the positive electrode side or reduction reactions on the negative electrode side, resulting in gas production.

[0091] Currently, lithium-ion batteries are the most widely used and well-developed type of battery. Improving energy density and charging speed are key goals in lithium-ion battery optimization. One solution to this problem is to design the electrolyte in lithium-ion batteries. Using high-conductivity, low-viscosity electrolytes can significantly improve battery energy density and charging speed. High-conductivity, low-viscosity electrolytes are highly reactive and easily undergo oxidation reactions on the positive electrode side or reduction reactions on the negative electrode side, generating large amounts of gas.

[0092] 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 battery cell housing. The provision of the vent assembly 90 can promptly exhaust gas from the interior of the battery cell to the exterior of the housing, maintaining the air pressure within the battery cell within a normal level, thereby improving the safety performance of the battery cell and significantly extending the life of the battery cell.

[0093] In this embodiment, the battery cell 20 also includes an electrolyte, which is filled in the accommodating cavity 221. 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, and 3-methyl-2-butanone. The above-mentioned electrolyte components have at least one of the two properties of high conductivity and low viscosity. When applied to the electrolyte system of the battery cell, they can achieve rapid ion migration and improve the charging capacity and energy density of the entire battery cell.

[0094] In this 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 cells. However, electrolyte components with high conductivity and low viscosity are often chain-like, low-molecular-weight organic compounds, which are highly reactive and more prone to oxidation / reduction reactions during charge and discharge. This increases gas production in the battery cells, leading to increased internal pressure in the battery cells and a series of adverse consequences.

[0095] Based on this, this application scheme thoroughly studies the gas production behavior of high-conductivity and low-viscosity electrolytes, and pairs battery cells with different electrolyte compositions with exhaust components with different exhaust rates. This balances the conflict between high energy density and charging capacity and high gas production. Furthermore, for some battery cells that do not require high conductivity, there is no need for exhaust components with large exhaust capacities, thus reducing the impact of external water vapor intrusion on the battery cells during the exhaust process.

[0096] In this application, battery cells with varying first component contents are equipped with exhaust assemblies with varying exhaust rates, balancing the conflict between high energy density and charging capacity with high gas production. Furthermore, for battery cells that don't require high conductivity, exhaust assemblies with high exhaust capacity are unnecessary, minimizing the impact of moisture intrusion on the battery cells during the exhaust process.

[0097] 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.

[0098] Optionally, the content of the first component is 15%-35%, and the content of the first component can be selected as 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. It 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, which is beneficial to maintaining the sealing of the battery cell.

[0099] In another embodiment, the content of the first component is greater than or equal to 50% based on the total mass of the electrolyte. Optionally, 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 the exhaust 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.

[0100] In one embodiment, the battery cell further includes an electrode assembly, which is accommodated in the accommodation cavity. The electrode assembly includes a negative electrode plate, which includes a negative electrode active material, and the negative electrode active material includes a silicon-based material.

[0101] The negative electrode active material is the carrier of conductive ions and electrons during the charging process of the battery cell, playing a role in energy storage and release. Therefore, it has a significant impact on the energy density and charging capacity of the battery cell. First, the specific capacity of the negative electrode 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. Second, the ion embedding performance of the negative electrode material can affect the charging rate of the battery cell. The faster the active ion embedding of the negative electrode material, the more conducive it is to improving the charging rate of the battery cell.

[0102] Silicon-based materials have a higher theoretical specific capacity (the theoretical specific capacity of silicon is as high as 4200mAh / g) and a lower lithium insertion potential, and have great application prospects in improving the energy density and charging capacity of battery cells.

[0103] However, when silicon-based materials are used as negative electrodes, the volume of silicon will expand by more than 300% when fully lithiated. This huge volume change will bring a series of problems, which may cause cracks or even pulverization of the silicon negative electrode material, detachment of the active material from the electrode, and rupture of the solid electrolyte interface film (SEI), resulting in rapid attenuation of the battery cell capacity and a significant decrease in cycle performance. At the same time, there will be a certain amount of gas production. The gas produced by the battery cell stays on the surface of the electrode, which will hinder the deintercalation and extraction of lithium, leading to deterioration of the battery cell performance. At the same time, if the gas produced by the battery cell is not discharged in time, it will cause the internal pressure of the battery cell to increase. Excessive internal pressure will have a negative impact on the performance and appearance of the battery cell, such as leakage, bulging, increased internal resistance of the battery cell, shortened discharge time and cycle life, and ultimately reduced long-term reliability of the battery cell and shortened the service life of the battery cell. Therefore, it is necessary to balance the relationship between the gas production of the battery cell and the electrolyte system.

[0104] In the present application, a battery cell using a silicon-based negative electrode active material is matched with an exhaust assembly to timely exhaust the gas inside the battery cell.

[0105] According to some embodiments of the present application, the electrolyte further includes a second component, and the second component includes fluoroethylene carbonate.

[0106] Fluoroethylene carbonate (FEC) has excellent electrolyte interface stability and can form a thin film covering the surface of the electrolyte, effectively preventing unnecessary reactions between the oxidizing components in the electrolyte and the negative electrode of the battery cell, thereby improving the cycle life and charge and discharge efficiency of the battery cell. The cycle performance of the silicon-based negative electrode can be improved by adding fluoroethylene carbonate (FEC) to the electrolyte. After the addition of FEC, the composition of the SEI film will change, and a layer of SEI film rich in lithium fluoride (LiF) will be generated on the surface of the negative electrode, which can significantly improve the cycle stability of the silicon-based negative electrode. However, the addition of FEC will worsen the gas production behavior and lead to an increase in gas production. In the present application scheme, when matching the exhaust component, an exhaust component with a relatively large exhaust rate is selected.

[0107] In one embodiment, the silicon content is less than or equal to 5% based on the total weight of the negative electrode active material. The silicon content of less than or equal to 5% can be 1%, 2%, 3%, 4%, or 5%. The electrolyte includes fluoroethylene carbonate, and the content of fluoroethylene carbonate is less than or equal to 3% based on the total weight of the electrolyte.

[0108] In this case, the fluoroethylene carbonate content is less than or equal to 3%, and can be 1%, 2%, or 3%. Adding fluoroethylene carbonate to the electrolyte can alleviate the expansion of silicon-based materials and improve the cycle stability of silicon-based negative electrodes. At the same time, considering the low silicon content, the negative impact of silicon-based material expansion is minimized, allowing for a lower fluoroethylene carbonate content to reduce costs.

[0109] In the above-mentioned negative electrode active material and corresponding electrolyte design, the content of fluoroethylene carbonate is low, so the gas generated is relatively small, which matches the exhaust component with a lower exhaust rate.

[0110] In one embodiment, the silicon content is greater than 5% based on the total mass of the negative electrode active material. The silicon content can be 6%, 10%, 20%, 30%, etc. The electrolyte includes fluoroethylene carbonate, and the fluoroethylene carbonate content is greater than 3% based on the total mass of the electrolyte. The fluoroethylene carbonate content can be 3%, 5%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, etc. The higher silicon content in this embodiment can further improve the battery's energy density and charging capacity; however, it also increases the negative impact of silicon expansion. The increased fluoroethylene carbonate content can further suppress the expansion of silicon-based negative electrode materials and increase gas production. A venting assembly with a higher exhaust rate can be used to promptly discharge generated gases, improving the battery's charging capacity and energy density while also ensuring the safety and service life of the battery cells.

[0111] In one embodiment, the electrolyte salt is an important component of the battery electrolyte and can improve the ionic conductivity of the electrolyte; forming a stable low-impedance SEI film is beneficial to improving the cycle performance of the battery. Selecting a suitable electrolyte salt can mitigate the impact of the cycle performance degradation caused by the silicon-based negative electrode. The fluoride ion in lithium bis(fluorosulfonyl)imide (LiFSI) has a strong electron-withdrawing property, which weakens the coordination effect between the anion and cation of the lithium salt, enhances the mobility of the lithium ion, and has high conductivity, thermal stability and electrochemical stability, and basically no side reactions occur, while also suppressing the expansion effect.

[0112] In one embodiment, the silicon content is less than or equal to 5% based on the total mass of the negative electrode active material, the electrolyte includes fluoroethylene carbonate, the content of fluoroethylene carbonate is less than or equal to 3% based on the total mass of the electrolyte, and the electrolyte salt includes LiFSI lithium salt.

[0113] The silicon content is less than or equal to 5%, and can be 1%, 2%, 3%, 4%, or 5%. In this case, the fluoroethylene carbonate content is less than or equal to 3%, and can be 1%, 2%, or 3%. Adding fluoroethylene carbonate to the electrolyte can alleviate silicon expansion and improve the cycle stability of the silicon-based negative electrode. At the same time, considering the low silicon content, the negative impact of silicon expansion is smaller, and a lower fluoroethylene carbonate content can be used to reduce costs.

[0114] In the above-mentioned negative electrode active material and corresponding electrolyte design, the content of fluoroethylene carbonate is low, so less gas is generated, which matches the exhaust component with a lower exhaust rate.

[0115] Through the above-mentioned arrangement, the gas generated in the battery cell can be discharged in time to maintain the normal air pressure in the battery cell; at the same time, the probability of external impurities (air, moisture, dust, etc.) entering the battery cell is reduced, and the air tightness of the battery cell is maintained; while improving the charging capacity and energy density of the battery cell, the safety performance and service life of the battery cell can be taken into account.

[0116] According to some embodiments of the present application, the silicon content is greater than 5% based on the total weight of the negative electrode active material, and the second component includes fluoroethylene carbonate, with the fluoroethylene carbonate content exceeding 3% based on the total weight of the electrolyte. The high fluoroethylene carbonate content, coupled with a vent assembly having a low exhaust rate, allows for timely exhaust of gases, quickly balancing the air pressure inside the battery cell housing with the external air pressure.

[0117] The silicon content can be 6%, 10%, 20%, 50%, 80%, etc., and as the fluoroethylene carbonate content increases, the exhaust rate of the exhaust assembly also increases. In this embodiment, the higher silicon content can further improve the energy density and charging capacity of the battery cell; the higher fluoroethylene carbonate content can further inhibit the expansion of the silicon-based negative electrode material; and the exhaust assembly with a higher exhaust rate can promptly exhaust generated gases, thereby improving the charging capacity and energy density of the battery cell while also taking into account the safety performance and service life of the battery cell.

[0118] In the above embodiments, the internal pressure of the battery cell is controlled by matching the corresponding exhaust components for different electrolyte components. Based on this, the energy density and charging speed of the battery cell can be improved by designing the negative active materials of the lithium-ion battery cell. For example, the selection of graphite mixed silicon negative electrode active materials can significantly improve the energy density of the battery cell. At the same time, additives that inhibit expansion are added to the electrolyte system to improve the cyclability of the battery cell. A matching exhaust component is also provided to promptly discharge the gas produced by the addition of the additive that inhibits expansion. The electrolyte components (solvents, additives) can also be screened and designed; a high-proportion high-conductivity component or a new high-conductivity component design can be introduced. The introduction of high-conductivity components can improve the energy density and charging rate. A matching exhaust component is also provided to promptly discharge the gas produced by the high-conductivity component.

[0119] In some embodiments, the positive electrode active material is the key to restricting the overall performance of the battery. By regulating the positive electrode active material, a battery with larger capacity and higher energy density can be designed. For example, the nickel (Ni) content in the ternary positive electrode material can be increased to obtain a higher gram capacity, thereby improving the energy density of the battery cell. However, a high nickel content will cause the positive electrode active material to become more oxidizable, resulting in gas production during the use of the battery cell. If the gas generated by the battery cell is not discharged in time, it will cause the internal pressure of the battery cell to increase. Excessive internal pressure will have a negative impact on the performance and appearance of the battery cell. For example, in severe cases, it will have a destructive effect on the performance and appearance of the battery cell, such as leakage, bulging, increased internal resistance of the battery cell, and shortened discharge time and cycle life.

[0120] 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 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 mass content of nickel in the first ternary material is greater than or equal to 50% and less than 100% (50% ≤ nickel content < 100%).

[0121] 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.

[0122] The "ternary" in ternary positive electrode materials refers to a polymer containing nickel (Ni), cobalt (Co), and manganese (Mn) or containing 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-ion 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 nickel, cobalt, and manganese ternary materials as an example: Ni exhibits high capacity and low safety; Co exhibits high cost and high stability; and 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] In one embodiment, the first ternary material has a median particle size Dv50 of 2-4 μm.

[0130] 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.

[0131] 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.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] In one embodiment, the first ternary material includes one or more of single crystal particles and polycrystalline particles.

[0138] 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.

[0139] In one embodiment, the positive electrode active material includes lithium manganese iron phosphate material.

[0140] In addition to ternary cathode materials, lithium iron phosphate cathode materials are also mainstream application materials for lithium-ion batteries, and lithium iron phosphate (LFP) cathode materials are superior in safety and low cost. However, for LFP batteries, the development of their energy density has almost reached its limit, and there is little room for performance improvement. The crystal structure of lithium manganese iron phosphate (LMFP) is similar to that of LFP, and it also has the characteristics of stable chemical properties and excellent safety performance. At the same time, the manganese element doped in LMFP can increase the charging voltage of the material, raising the charging voltage from 3.4V of LFP to 4.1V, which increases the theoretical energy density of LMFP batteries by 15-20%. In addition, LMFP has better safety performance than ternary cathode materials, and at the same time has a low dependence on rare metals and can be produced on the same line as LFP, with obvious cost advantages.

[0141] In one embodiment, improving the battery energy density can also be achieved by increasing the thickness of the positive electrode active layer. In the preparation of the electrode, increasing the coating thickness of the active coating can increase the load of the electrode and increase the energy density of the battery. However, thicker electrodes will increase the length of the ion transmission path and the internal impedance of the battery, so a high-kinetic electrolyte is needed. High-kinetic electrolytes generally have higher lithium ion transmission speeds, which can compensate for the problems of increased ion diffusion paths and increased internal battery impedance caused by increasing the thickness of the positive electrode sheet. High-kinetic electrolytes may cause an increase in gas production from electrolyte decomposition.

[0142] In one embodiment, the thickness of the positive electrode active material is greater than or equal to 130 μm. The thickness of the positive electrode active material can be 130 μm, 150 μm, 170 μm, 200 μm, 220 μm, etc. In this case, the greater thickness of the positive electrode active material can increase the electrode load and thus the energy density of the battery. A vent assembly with an appropriate exhaust rate can promptly exhaust gas generated by the battery, balancing energy density and safety performance.

[0143] In addition, when the thickness of the positive electrode active layer is greater than or equal to 130 μm, the positive electrode active layer material includes at least one of the first type of material and the second type of material, the first type of material includes the first ternary material, and the second type of positive electrode material includes lithium manganese iron phosphate material; it may also include the second ternary material.

[0144] 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 0.025 mL / day to 8 mL / day.

[0145] 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 cell can be sealed to discharge internal gas through the breathable membrane, promptly discharging the gas inside the battery cell housing to the outside of the housing. This prevents the air pressure inside the battery cell housing from becoming excessively high, preventing the pressure relief mechanism from prematurely opening the valve, and significantly extending the battery cell lifespan.

[0146] 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 cell will cause the internal pressure to rise rapidly, the breathable membrane needs to have certain mechanical strength and elasticity.

[0147] The air permeability of the breathable membrane depends on its properties. A polymer membrane with a certain porosity can be selected as the breathable membrane, and breathable membranes with different air permeability can be prepared by selecting materials with different porosities. For example, the air permeability of the breathable membrane can be 0.025 mL / day, 0.05 mL / day, 0.1 mL / day, 0.3 mL / day, 0.5 mL / day, 1.0 mL / day, 1.5 mL / day, 2.5 mL / day, 3.0 mL / day, 3.5 mL / day, 4.0 mL / day, 5.0 mL / day, 6.5 mL / day, 7.0 mL / day, 7.5 mL / day, or 8.0 mL / day. The air permeability test conditions for the breathable membrane are 23°C, 0% RH (0% humidity), and 0.1 MPa air pressure. The test method refers to the standard GB / T1038-2000.

[0148] According to some embodiments of the present application, the breathable membrane includes a first breathable membrane having a permeability rate of 0.025-4 mL / day. This can be applied in scenarios with low gas production. In other words, when the exhaust assembly requires a low exhaust rate, a breathable membrane assembly including the first breathable membrane can be selected.

[0149] According to some embodiments of the present application, the breathable membrane includes a second breathable membrane with a permeability rate of 5-8 mL / day. This can be applied in scenarios with high gas production. In other words, when the exhaust assembly requires a higher exhaust rate, a breathable membrane assembly including a second breathable membrane can be selected.

[0150] 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.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] 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.

[0157] 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.

[0158] 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.

[0159] 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.

[0160] According to some embodiments of the present application, the exhaust assembly may be a breathable membrane assembly or a one-way valve. For example, the exhaust assembly may be a breathable membrane assembly comprising a first breathable membrane, a breathable membrane assembly comprising a second breathable membrane, or a one-way valve with a cracking pressure greater than 0.4 MPa; or a breathable membrane assembly comprising a second breathable membrane, or a one-way valve with a cracking pressure greater than 0.2 MPa.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] 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.

[0165] According to some embodiments of the present application, the opening pressure of the one-way valve 30 is greater than or equal to 0.4 MPa, the breathable membrane assembly 40 includes a second breathable membrane, and the breathability rate of the second breathable membrane is 5-8 mL / day.

[0166] Please refer to Figure 4, 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 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.

[0167] 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.

[0168] 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.

[0169] 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.

[0170] 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, and the breathable membrane assembly 40 includes a first breathable membrane, and the breathability rate of the first breathable membrane is 0.025-4 mL / day.

[0171] 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.

[0172] 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.

[0173] Please refer to Figures 5, 6, and 7. Figure 5 is a front view of a one-way valve according to one or more embodiments, Figure 6 is an exploded structural diagram of a one-way valve according to one or more embodiments, and Figure 7 is a partial cross-sectional structural diagram 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.

[0174] 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.

[0175] 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 cell.

[0176] 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.

[0177] 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 cell system during the valve opening period.

[0178] 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.

[0179] 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 the 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 channel of the valve cavity 313. The valve core 32 is configured to open the air inlet channel in response to gas within the housing, thereby releasing gas from the battery cells.

[0180] 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 body 311 extending into the housing. When the air inlet is provided on the outer circumferential surface of the portion of the valve body 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.

[0181] 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.

[0182] 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.

[0183] 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,

[0184] The breathable membrane assembly 40 includes a breathable membrane 41 and a connector 42. The connector 42 is used to support the breathable membrane 41. The connector 42 is provided with a first vent 491. The breathable membrane 41 is disposed on the connector 42 and covers the first vent 491. The breathable membrane is configured to allow gas inside the battery cell to pass through the breathable membrane and be discharged.

[0185] 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 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. Optionally, the aperture of the first air hole 491 can be less than or equal to the aperture of the exhaust hole on the battery cell.

[0186] 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.

[0187] 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 .

[0188] 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 .

[0189] 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 .

[0190] 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.

[0191] 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.

[0192] 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.

[0193] 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.

[0194] The first annular table surface T1 and the second annular table surface 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 a portion of the structure. The depth of the depressions of the first annular table surface T1 and the second annular table surface 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. Preferably, the depth of the depression of the second annular table surface T2 relative to the first annular table surface 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 surface 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 .

[0195] 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 .

[0196] 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 cross-sectional view of a battery cell according to one or more embodiments; and Figure 14 is a front view of an end cap of a battery cell according to one or more embodiments.

[0197] 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.

[0198] 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.

[0199] 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.

[0200] 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.

[0201] 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.

[0202] 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. Preferably, 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 way, 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.

[0203] As shown in Figure 13 , the breathable membrane 41 can be positioned on the side of the metal member 42 facing the interior of the housing; that is, the breathable membrane 41 is positioned below the metal member 42. This arrangement reduces the impact of the operating environment of the battery cell 20 on the breathable membrane 41. In other embodiments, the breathable membrane 41 can also be positioned 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 reduces erosion of the breathable membrane 41 by the electrolyte system.

[0204] 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 cross-sectional structure of the battery cell according to one or more embodiments; Figure 17 is a front view of the end cover of the battery cell according to one or more embodiments.

[0205] 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.

[0206] 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.

[0207] 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.

[0208] 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.

[0209] 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 .

[0210] 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.

[0211] 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.

[0212] 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.

[0213] 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.

[0214] 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.

[0215] 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 .

[0216] 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 .

[0217] 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.

[0218] 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.

[0219] 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.

[0220] 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.

[0221] 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.

[0222] 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.

[0223] 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 .

[0224] 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.

[0225] 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.

[0226] 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.

[0227] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0228] 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.

[0229] 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.

[0230] Electrical equipment can choose battery cells, battery modules or battery packs according to its usage requirements.

[0231] 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.

[0232] 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.

[0233] 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, characterized in that: 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 electrolyte filling the accommodating cavity; 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.

2. The battery cell according to claim 1, wherein: Based on the total mass of the electrolyte, the content of the first component is 5%-85%.

3. The battery cell according to claim 1 or 2, characterized in that: The content of the first component is 15%-35%.

4. The battery cell according to claim 1 or 2, characterized in that: Based on the total mass of the electrolyte, the content of the first component is 65%-85%.

5. The battery cell according to any one of claims 1 to 4, characterized in that: The battery cell further includes an electrode assembly, which is accommodated in the accommodation cavity. The electrode assembly includes a negative electrode plate, which includes a negative electrode active material, and the negative electrode active material includes a silicon-based material.

6. The battery cell according to claim 5, characterized in that Based on the total mass of the negative electrode active material, the silicon content is less than or equal to 5%; the electrolyte further includes fluoroethylene carbonate, and based on the total mass of the electrolyte, the content of the fluoroethylene carbonate is less than or equal to 3%.

7. The battery cell according to claim 5, characterized in that Based on the total mass of the negative electrode active material, the silicon content is greater than 5%; the electrolyte further includes fluoroethylene carbonate, and based on the total mass of the electrolyte, the content of the fluoroethylene carbonate is greater than 3%.

8. The battery cell according to any one of claims 1 to 7, characterized in that: The battery cell also includes an electrode assembly, which is accommodated in the accommodating cavity. The electrode assembly includes a positive electrode plate, and the positive electrode plate includes a positive electrode active material. The positive electrode active material includes a first type of material, and the first type of material includes a first ternary material. The mass content of nickel in the first ternary material is 50%≤nickel content<100%.

9. The battery cell according to claim 8, characterized in that The median particle size Dv50 of the first ternary material is 2-4 μm.

10. The battery cell according to claim 8 or 9, characterized in that: The mass content of cobalt in the first ternary material is 12%-18%.

11. The battery cell according to any one of claims 8 to 10, characterized in that: 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%.

12. The battery cell according to any one of claims 8 to 11, characterized in that: The first ternary material includes one or more of single crystal particles and polycrystalline particles.

13. The battery cell according to any one of claims 8 to 12, characterized in that: The positive electrode active material further includes lithium manganese iron phosphate material.

14. The battery cell according to any one of claims 8 to 13, characterized in that: The thickness of the positive electrode active material is greater than or equal to 130 μm.

15. The battery cell according to any one of claims 1 to 14, characterized in that: 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 0.025 mL / day to 8 mL / day.

16. The battery cell according to claim 15, characterized in that 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 the gas inside the battery cell to pass through the breathable hole. Membrane discharge.

17. The battery cell according to claim 15 or 16, characterized in that: The exhaust assembly includes a one-way valve, and the opening pressure of the one-way valve is greater than or equal to 0.2 MPa; optionally, greater than or equal to 0.4 MPa; and further optionally, greater than or equal to 0.8 MPa.

18. The battery cell according to claim 17, characterized in that The exhaust assembly includes a 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.

19. The battery cell according to claim 18, characterized in that 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 through hole segment connects the inside of the shell with the outside of the shell. 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 is at least partially accommodated in the first hole segment.

20. The battery cell according to claim 19, characterized in that 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.

21. The battery cell according to claim 19, characterized in that 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.

22. The battery cell according to claim 19, characterized in that 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.

23. The battery cell according to claim 15 or 16, characterized in that: The exhaust assembly includes a 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 flows through the breathable membrane assembly.

24. The battery cell according to any one of claims 1 to 14, characterized in that: The exhaust assembly includes a one-way valve, and the opening pressure of the one-way valve is greater than or equal to 0.2 MPa; optionally, greater than or equal to 0.4 MPa; and further optionally, greater than or equal to 0.8 MPa.

25. The battery cell according to claim 24, characterized in that 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.

26. A battery, characterized in that: The battery cell comprises the battery cell according to any one of claims 1 to 25.

27. An electrical device, characterized in that: The battery cell comprises the battery cell according to any one of claims 1 to 25, wherein the battery cell is used to provide electrical energy.

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