Isolating membrane, battery and electric device

Abstract

The invention provides an isolating membrane and a preparation method thereof, a secondary battery and an electric device, the isolating membrane comprises a base membrane and a filler arranged in a porous structure of the base membrane, the filler comprises a polymer matrix, an electrolyte salt and a plasticizer, the polymer matrix comprises a copolymer of a first monomer unit and a second monomer unit, the first monomer unit comprises an olefinic bond type unsaturated carbonate monomer unit, an olefinic bond type unsaturated sulfate monomer unit, an olefinic bond type unsaturated sulfonate monomer unit, an olefinic bond type unsaturated sulfone monomer unit, an olefinic bond type unsaturated carboxylic ester monomer and an olefinic bond type unsaturated phosphate monomer unit; the first monomer unit is at least one of an ethylenically unsaturated nitrile monomer unit and an ethylenically unsaturated ether monomer unit, and the second monomer unit comprises an acrylate monomer unit. The isolating membrane provided by the invention can improve the cycle performance of the battery.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and in particular, to a separator, a battery, and an electrical device. Background Art

[0002] The statements herein only provide background information related to the present application and do not necessarily constitute prior art.

[0003] In recent years, with the increasingly wide application range of secondary batteries represented by lithium-ion batteries, secondary batteries are widely used in energy storage power systems such as hydroelectric, thermal, wind, and solar power stations, as well as in multiple fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. Due to the great development of secondary batteries, higher requirements are also put forward for their energy density, cycle performance, safety performance, etc. In secondary batteries, as one of the key components of the battery, the separator is mainly used to isolate the positive and negative electrodes, provide an ion penetration channel between the positive and negative electrodes, and has the ability to absorb and retain the electrolyte to achieve the normal cyclic charge and discharge operation of the battery. Although the battery separator does not directly participate in the electrochemical reaction, it also has an impact on the cycle performance of the battery. Summary of the Invention

[0004] The present application provides a separator, a battery, and an electrical device, which can improve the cycle life of the battery.

[0005] In a first aspect of the present application, a separator is provided, including a base film and a filler disposed in a porous structure of the base film. The filler includes a polymer matrix, an electrolyte salt, and a plasticizer. The polymer matrix includes a copolymer of a first monomer unit and a second monomer unit; the first monomer unit includes at least one of a vinyl unsaturated carbonate monomer unit, a vinyl unsaturated sulfate monomer unit, a vinyl unsaturated sulfonate monomer unit, a vinyl unsaturated sulfone monomer unit, a vinyl unsaturated carboxylate monomer, a vinyl unsaturated phosphate monomer unit, a vinyl unsaturated nitrile monomer unit, and a vinyl unsaturated ether monomer unit, and the second monomer unit includes an acrylate monomer unit.

[0006] In the separator provided by the present application, the fillers disposed in the porous structure of the base film include a polymer matrix, an electrolyte salt, and a plasticizer. Among them, the polymer matrix has a relatively high density, can provide a high air permeability for the separator, and the polymer matrix basically does not depolymerize during the traditional high-temperature formation process. At the same time, the electrolyte salt dispersed in the plasticizer contained in the filler can enhance the ionic conductivity of the separator to active ions. Thus, the above fillers can enable the separator to have a high air permeability and density while effectively conducting active ions, thereby effectively blocking the mutual diffusion between other components in the electrolyte between the positive and negative electrodes except for the active ions, reducing the performance deterioration caused by the mutual diffusion of the by-products of the positive and negative electrodes to the other side, and improving the cycle performance of the battery.

[0007] In some embodiments, the number of acrylate groups contained in the acrylate monomer unit is ≥2. In this way, the acrylate monomer has more cross-linking sites, which can improve the cross-linking degree of the formed polymer matrix. Therefore, it is beneficial to improve the density of the polymer matrix and enable the polymer matrix to better bind the plasticizer and the electrolyte salt therein, thereby further improving the air permeability and ionic conductivity of the separator.

[0008] In some embodiments, based on the total mass of the polymer matrix, the mass percentage of the first monomer unit in the polymer matrix is 16% - 67%.

[0009] In some embodiments, based on the total mass of the polymer matrix, the mass percentage of the first monomer unit in the polymer matrix is 16% - 35%.

[0010] When the mass percentage of the first monomer unit in the polymer matrix is within this range, it is beneficial to further improve the air permeability and ionic conductivity of the separator.

[0011] In some embodiments, the polymer matrix further includes a homopolymer or copolymer of the first monomer unit. In this way, it is beneficial to further improve the density of the polymer matrix, thereby further improving the air permeability of the separator.

[0012] In some embodiments, the acrylate monomer units include one or more of ethylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,3-butanediol diacrylate, 1,3-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, dipropylene glycol diacrylate, dipropylene glycol dimethacrylate, tripropylene glycol diacrylate, tripropylene glycol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, 2(propoxylated)neopentyl glycol diacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, polycyclohexyl acrylate, methoxypolyethylene glycol acrylate, ethoxylated trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, methoxypolyethylene glycol methacrylate, pentaerythritol triacrylate, propoxylated glycerol triacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate, bis(trimethylolpropane)tetraacrylate, pentaerythritol tetraacrylate, 4(ethoxy)pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate.

[0013] In some embodiments, the ethylenically unsaturated carbonate monomer units include one or more of vinylene carbonate, ethylene ethylenecarbonate, ethylene carbonate, propylene carbonate, butylene carbonate, fluorinated ethylene carbonate, and chlorinated ethylene carbonate;

[0014] and / or, the ethylenically unsaturated sulfate monomer units include one or more of ethylene vinyl sulfite, vinyl sulfite, 4-methyl vinyl sulfate, and 4-ethyl vinyl sulfate;

[0015] and / or, the ethylenically unsaturated sulfonate monomer units include one or more of 1,3-propane sultone, allyl p-toluenesulfonate, and 2,2-difluoro vinyl 4-methylbenzenesulfonate;

[0016] and / or, the ethylenically unsaturated sulfone monomer units include one or more of methyl vinyl sulfone, ethyl vinyl sulfone, cyclobutene sulfone, sulfolane, and cyclohexene sulfoxide;

[0017] and / or, the ethylenically unsaturated carboxylic acid ester monomer includes vinyl acetate;

[0018] And / or, the ethylenically unsaturated phosphate monomer units include one or more of dimethyl vinyl phosphate, diethyl vinyl phosphate, diethyl allyl phosphate, diethyl butenyl phosphate, diethyl 1-buten-2-yl phosphonate, diethyl ethynyl phosphate, vinyl trifluoromethyl phosphate, vinyl-1-trifluoroethyl phosphate, diethyl fluoro vinyl phosphate, 1-trifluoropropenyl ethyl phosphate;

[0019] And / or, the ethylenically unsaturated nitrile monomer units include one or more of acrylonitrile, succinonitrile, glutaronitrile, adiponitrile;

[0020] And / or, the ethylenically unsaturated ether monomer units include one or more of 1,3-dioxolane, ethylene oxide, 1,2-epoxypropane, 4-methyl-1,3-dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, ethylene glycol dimethyl ether, ethylene glycol diglycidyl ether, triethylene glycol divinyl ether.

[0021] In some embodiments, the electrolyte salt includes at least one of a lithium salt and a sodium salt. The electrolyte salt is beneficial to improving the ionic conductivity of the separator membrane, enabling active ions to effectively conduct between the positive and negative electrodes through the separator membrane.

[0022] In some embodiments, the electrolyte salt includes at least one of a lithium salt and a sodium salt.

[0023] In some embodiments, the lithium salt includes one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorooxalate borate, lithium bis(oxalate) borate, lithium difluorophosphate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate;

[0024] And / or, the sodium salt includes one or several of NaPF6, NaClO4, NaBCl4, NaSO3CF3, and Na(CH3)C6H4SO3.

[0025] The electrolyte salt is beneficial to improving the ionic conductivity of the separator membrane, enabling active ions to effectively conduct between the positive and negative electrodes through the separator membrane.

[0026] In some embodiments, the plasticizer includes at least one of chain ester organic solvents, cyclic ester organic solvents, ether organic solvents, and sulfone organic solvents.

[0027] The filler includes a plasticizer which can be used to dissolve and disperse the electrolyte salt. The higher the content of the plasticizer, the more electrolyte salt is bound in the polymer matrix, and the better the performance of the separator in conducting active ions. In addition, selecting the above types of plasticizers is beneficial to further improve the ionic conductivity of the separator, and is also beneficial to improve the toughness of the separator, thereby enhancing its mechanical properties.

[0028] In some embodiments, the mass ratio of the polymer matrix in the filler is 10% - 50%;

[0029] and / or, the mass ratio of the electrolyte salt in the filler is 10% - 20%;

[0030] and / or, the mass ratio of the plasticizer in the filler is 40% - 70%.

[0031] When the mass ratio of the polymer matrix in the filler is within the above range, the separator can obtain a relatively high air permeability, enabling the separator to play a relatively high blocking role in the diffusion of other components in the electrolyte except active ions between the positive and negative electrodes.

[0032] In some embodiments, the separator further includes the filler disposed on at least a part of the surface of the base film.

[0033] Disposing the filler on at least a part of the surface of the base film is beneficial to further improve the air permeability of the separator, thereby further enhancing the blocking effect of the separator on the mutual diffusion of other components in the electrolyte except active ions between the positive and negative electrodes, and further improving the cycle performance of the battery.

[0034] In some embodiments, the separator further includes an inorganic coating disposed on at least one surface of the base film, and the inorganic coating includes inorganic particles.

[0035] The setting of the inorganic coating is beneficial to enhance the affinity between the base film and the composition forming the filler, improve the liquid absorption capacity of the base film, so that the porous structure of the base film is completely wetted by the composition, thereby improving the filling degree of the filler in the porous structure of the base film, and further improving the air permeability of the separator and its blocking performance on the mutual diffusion of other components in the electrolyte except active ions.

[0036] In some embodiments, the filler is disposed inside the inorganic coating and / or on at least a part of the surface of the inorganic coating.

[0037] Disposing the filler inside the inorganic coating and / or on at least a part of the surface is beneficial to improve the density of the inorganic coating, thereby further improving the air permeability of the separator and its blocking performance on the mutual diffusion of other components in the positive and negative electrode electrolytes except active ions.

[0038] In some embodiments, the base film includes at least one of a polyolefin base film, a polyvinyl fluoride base film, a cellulose nanofiber-containing base film, or a polyimide base film.

[0039] In some embodiments, the air permeability AP of the separator film satisfies: AP≥20000 s / 100 mL, and the ionic conductivity λ of the separator film satisfies: λ≥0.1 mS / cm.

[0040] When the air permeability of the separator film meets the above range, it can effectively enhance the blocking effect of the separator film on the mutual diffusion of other components in the electrolyte except for the active ions. When different electrolytes are used for the positive electrode and the negative electrode respectively, it can effectively reduce the mutual diffusion and mixing of other components in the positive electrode electrolyte except for the active ions and other components in the negative electrode electrolyte except for the active ions, thereby reducing the performance deterioration caused by the mutual diffusion of the by-products of the positive and negative electrodes to the other side, and improving the cycle performance of the battery. At the same time, when the ionic conductivity λ of the separator film meets the above range, it can enhance its conduction effect on the active ions, further improving the cycle performance of the battery.

[0041] In some embodiments, the air permeability of the separator film satisfies: 31000 s / 100 mL≤AP≤50100 s / 100 mL.

[0042] When the air permeability AP of the separator film is within this range, it is beneficial to further enhance the blocking effect of the separator film on the mutual diffusion of other components in the electrolyte except for the active ions, and further improve the cycle performance of the battery.

[0043] In some embodiments, the ionic conductivity λ of the separator film satisfies: 0.2 mS / cm≤λ<0.6 mS / cm.

[0044] When the ionic conductivity λ of the separator film is within this range, it is beneficial to further enhance the conduction effect of the separator film on the active ions.

[0045] The second aspect of the present application provides a battery, including a positive electrode plate, a negative electrode plate, and the separator film described in the first aspect of the present application, and the separator film is disposed between the positive electrode plate and the negative electrode plate.

[0046] In some embodiments, the battery further includes a first electrolyte disposed between the positive electrode plate and the separator film, and a second electrolyte disposed between the negative electrode plate and the separator film.

[0047] In some embodiments, the composition of the first electrolyte is different from that of the second electrolyte;

[0048] and / or, the content of the first electrolyte is different from that of the second electrolyte.

[0049] The third aspect of the present application provides an electrical device, including the battery of the second aspect of the present application.

[0050] In some embodiments, the battery includes a positive electrolyte and a negative electrolyte, and the composition and / or content of the positive electrolyte are different from those of the negative electrolyte.

[0051] The electrical device of the present application includes the battery provided by the present application, and thus has at least the same advantages as the battery.

[0052] Details of one or more embodiments of the present application are set forth in the following drawings and description. Other features, objects, and advantages of the present application will become apparent from the specification, drawings, and claims. Description of the Drawings

[0053] To better describe and illustrate the embodiments or examples provided by the present application, one or more drawings may be referred to. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed application, the currently described embodiments or examples, and the currently understood best mode of these applications. Moreover, in all the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0054] Figure 1 It is a schematic diagram of a battery cell of an embodiment of the present application.

[0055] Figure 2 is Figure 1 An exploded view of the battery cell of an embodiment of the present application shown.

[0056] Figure 3 It is a schematic diagram of a battery module of an embodiment of the present application.

[0057] Figure 4 It is a schematic diagram of a battery pack of an embodiment of the present application.

[0058] Figure 5 is Figure 4 An exploded view of the battery pack of an embodiment of the present application shown.

[0059] Figure 6 It is a schematic diagram of an electrical device using a secondary battery as a power source according to an embodiment of the present application.

[0060] Description of the Reference Numerals:

[0061] 1 Battery pack; 2 Upper box body; 3 Lower box body; 4 Battery module; 5 Battery cell; 51 Housing; 52 Electrode assembly; 53 Cover plate; 6 Electrical device. Detailed Embodiments

[0062] Hereinafter, some embodiments of the separator of the present application, its preparation method, secondary battery, and electrical device are described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary details are omitted. For example, there are cases where the detailed description of well-known matters and the repeated description of actually identical structures are omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter recited in the claims.

[0063] The "range" disclosed in the present application can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a specific range. The range defined in this way can include or not include the end values. Any end value can be independently included or not included, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, ranges of 60 - 110 and 80 - 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are also listed, the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5. In the present application, unless otherwise specified, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" are fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. Additionally, when it is stated that a certain parameter is an integer ≥2, it is equivalent to listing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For example, when it is stated that a certain parameter is an integer selected from "2 - 10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0064] In the present application, when it comes to "a plurality of", "a variety of", etc., unless otherwise specified, it means greater than 2 or equal to 2 in quantity. For example, "one or more" means one or greater than or equal to two.

[0065] If there is no special description, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0066] References to "embodiments" in this document mean that specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment or implementation of the present application. The appearance of this phrase at various positions in the specification does not necessarily refer to the same embodiment, nor are they independent or alternative embodiments mutually exclusive of other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments. Similar understanding applies to "implementations" mentioned in this document.

[0067] Those skilled in the art will understand that in the methods of each implementation or embodiment, the written order of each step does not imply a strict execution order that would impose any limitation on the implementation process. The detailed execution order of each step should be determined based on its function and possible internal logic. If there is no special indication, all steps of the present application can be carried out sequentially or randomly, preferably sequentially. For example, when the method includes steps (a) and (b), it means that the method may include steps (a) and (b) carried out sequentially, or may also include steps (b) and (a) carried out sequentially. For example, when it is mentioned that the method may further include step (c), it means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or may also include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0068] In the present application, in open technical features or technical solutions described using words such as "containing", "comprising", "including", etc., unless otherwise stated, additional members other than the listed members are not excluded. It can be regarded as providing both a closed feature or solution composed of the listed members and an open feature or solution that also includes additional members outside the listed members. For example, if A includes a1, a2, and a3, unless otherwise stated, it may also include other members or may not include additional members. It can be regarded as providing both a feature or solution where "A consists of a1, a2, and a3" and a feature or solution where "A not only includes a1, a2, and a3, but also includes other members". In the present application, unless otherwise stated, A (such as B) means that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0069] In the present application, "optionally", "optional", "option" mean that it can be present or absent, that is, it refers to either of the two alternative options of "present" or "absent". If the term "optional" appears multiple times in a technical solution, unless otherwise stated and there are no contradictions or mutual constraints, each "optional" is independent of the others.

[0070] Unless otherwise stated or there are contradictions, the terms or phrases used in this document have the following meanings:

[0071] The term "active ion" refers to ions that can intercalate and deintercalate between the positive and negative electrodes of a secondary battery, including but not limited to lithium ions, sodium ions, etc.

[0072] The term "monomer unit" refers to a general term for small molecules that can polymerize with the same or other molecules, which includes both organic small molecule compounds capable of polymerization and oligomers or prepolymers of organic small molecule compounds capable of polymerization, etc.

[0073] The term "carbonates" refers to the general name of compounds in which the hydrogen atoms of two hydroxyl groups (-OH) in a carbonic acid molecule are partially or completely replaced by alkyl groups.

[0074] The term "sulfates" refers to the general name of compounds in which the hydrogen atom in the hydroxyl group of sulfuric acid is replaced by a hydrocarbon group.

[0075] The term "sulfonates" refers to the general name of organic esters of sulfonic acid, which are compounds containing a sulfonic acid group and an ester group in their molecular structure.

[0076] The term "phosphates" refers to the general name of ester derivatives of phosphoric acid, which are compounds in which some or all of the hydroxyl hydrogen atoms in a phosphoric acid molecule are replaced by alkyl groups.

[0077] The term "carboxylates" refers to compounds formed by the dehydration condensation of carboxylic acids and alcohols, that is, the general name of compounds in which the -OH of the carboxyl group is replaced by an alkoxy group.

[0078] The term "sulfones" refers to the general name of a class of organic compounds characterized by having a sulfonyl group and usually being linked to two carbon atoms through sulfur (such as to two hydrocarbon groups or a simple divalent group).

[0079] The term "amides" refers to the general name of organic compounds in which the hydroxyl group in a carboxylic acid is replaced by an amino group or an amine group.

[0080] The term "nitriles" refers to the general name of organic compounds formed by the connection of carbon atoms containing a hydrocarbon group and a cyano group, which are a class of organic compounds containing the organic group -CN.

[0081] The term "ethers" refers to the general name of organic compounds in which the hydrogen in the hydroxyl group of an alcohol or a phenol is replaced by a hydrocarbon group.

[0082] The term "alkyl" refers to a saturated hydrocarbon containing primary (normal) carbon atoms, or secondary carbon atoms, or tertiary carbon atoms, or quaternary carbon atoms, or a combination thereof. A phrase containing this term, for example, "C1-C9 alkyl" refers to an alkyl group containing 1 to 9 carbon atoms, which may, each time it appears, independently of one another, be a C1 alkyl group, a C2 alkyl group, a C3 alkyl group, a C4 alkyl group, a C5 alkyl group, a C6 alkyl group, a C7 alkyl group, a C8 alkyl group or a C9 alkyl group. Suitable examples include, but are not limited to: methyl (Me, -CH3), ethyl (Et, -CH2CH3), 1-propyl (n-Pr, n-propyl, -CH2CH2CH3), 2-propyl (i-Pr, i-propyl, -CH(CH3)2), 1-butyl (n-Bu, n-butyl, -CH2CH2CH2CH3), 2-methyl-1-propyl (i-Bu, i-butyl, -CH2CH(CH3)2), 2-butyl (s-Bu, s-butyl, -CH(CH3)CH2CH3), 2-methyl-2-propyl (t-Bu, t-butyl, -C(CH3)3), 1-pentyl (n-pentyl, -CH2CH2CH2CH2CH3), 2-pentyl (-CH(CH3)CH2CH2CH3), 3-pentyl (-CH(CH2CH3)2), 2-methyl-2-butyl (-C(CH3)2CH2CH3), 3-methyl-2-butyl (-CH(CH3)CH(CH3)2), 3-methyl-1-butyl (-CH2CH2CH(CH3)2), 2-methyl-1-butyl (-CH2CH(CH3)CH2CH3), 1-hexyl (-CH2CH2CH2CH2CH2CH3), 2-hexyl (-CH(CH3)CH2CH2CH2CH3), 3-hexyl (-CH(CH2CH3)(CH2CH2CH3)), 2-methyl-2-pentyl (-C(CH3)2CH2CH2CH3), 3-methyl-2-pentyl (-CH(CH3)CH(CH3)CH2CH3), 4-methyl-2-pentyl (-CH(CH3)CH2CH(CH3)2), 3-methyl-3-pentyl (-C(CH3)(CH2CH3)2), 2-methyl-3-pentyl (-CH(CH2CH3)CH(CH3)2), 2,3-dimethyl-2-butyl (-C(CH3)2CH(CH3)2), 3,3-dimethyl-2-butyl (-CH(CH3)C(CH3)3) and octyl (-(CH2)7CH3).

[0083] The term "cycloalkyl" refers to a non-aromatic hydrocarbon containing cyclic carbon atoms, which can be a monocyclic alkyl, a spirocyclic alkyl, or a bridged cyclic alkyl. A phrase containing this term, for example, "C3-C9 cycloalkyl" refers to a cycloalkyl containing 3 to 9 carbon atoms, and each occurrence can independently be a C3 cycloalkyl, a C4 cycloalkyl, a C5 cycloalkyl, a C6 cycloalkyl, a C7 cycloalkyl, a C8 cycloalkyl, or a C9 cycloalkyl. Suitable examples include but are not limited to: cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and cycloheptyl. Additionally, "cycloalkyl" can also contain one or more double bonds, and representative examples of cycloalkyls containing double bonds include cyclopentenyl, cyclohexenyl, cyclohexadienyl, and cyclobutadienyl.

[0084] The term "alkenyl" refers to a hydrocarbon containing a positive carbon atom, a secondary carbon atom, a tertiary carbon atom, or a cyclic carbon atom having at least one unsaturated site, i.e., a carbon-carbon sp 2 double bond. A phrase containing this term, for example, "C2-C9 alkenyl" refers to an alkenyl containing 2 to 9 carbon atoms, and each occurrence can independently be a C2 alkenyl, a C3 alkenyl, a C4 alkenyl, a C5 alkenyl, a C6 alkenyl, a C7 alkenyl, a C8 alkenyl, or a C9 alkenyl. Suitable examples include but are not limited to: vinyl (-CH=CH2), allyl (-CH2CH=CH2), cyclopentenyl (-C5H7), and 5-hexenyl (-CH2CH2CH2CH2CH=CH2).

[0085] The term "alkynyl" refers to a hydrocarbon containing a positive carbon atom, a secondary carbon atom, a tertiary carbon atom, or a cyclic carbon atom having at least one unsaturated site, i.e., a carbon-carbon sp triple bond. A phrase containing this term, for example, "C2-C9 alkynyl" refers to an alkynyl containing 2 to 9 carbon atoms, and each occurrence can independently be a C2 alkynyl, a C3 alkynyl, a C4 alkynyl, a C5 alkynyl, a C6 alkynyl, a C7 alkynyl, a C8 alkynyl, or a C9 alkynyl. Suitable examples include but are not limited to: ethynyl (-C≡CH) and propargyl (-CH2C≡CH).

[0086] The term "aryl" refers to an aromatic hydrocarbon group derived by removing one hydrogen atom from an aromatic ring compound, which can be a monocyclic aryl, a fused-ring aryl, or a polycyclic aryl. For a polycyclic ring species, at least one is an aromatic ring system. For example, "C5-C 20 aryl" refers to an aryl containing 5 to 20 carbon atoms, and each occurrence can independently be a C5 aryl, a C6 aryl, a C 10 aryl, a C 14 aryl, a C 18 aryl, or a C 20Aryl. Suitable examples include, but are not limited to: benzene, biphenyl, naphthalene, anthracene, phenanthrene, dibenzo[a,l]pyrene, triphenylene, and their derivatives. It is understood that multiple aryl groups can also be interrupted by short non-aromatic units (e.g., <10% non-H atoms such as C, N, or O atoms), such as acenaphthene, fluorene, or 9,9-diarylfluorene, triarylamine, and diaryl ether systems should also be included in the definition of aryl.

[0087] The term "heteroaryl" means that at least one carbon atom in the aryl group is replaced by a non-carbon atom, and the non-carbon atom can be an N atom, an O atom, an S atom, etc. For example, "C3~C 10 heteroaryl" means a heteroaryl group containing 3 to 10 carbon atoms, and each occurrence can be independently a C3 heteroaryl group, a C4 heteroaryl group, a C5 heteroaryl group, a C6 heteroaryl group, a C7 heteroaryl group, or a C8 heteroaryl group. Suitable examples include, but are not limited to: furan, benzofuran, thiophene, benzothiophene, pyrrole, pyrazole, triazole, imidazole, oxazole, oxadiazole, thiazole, tetrazole, indole, carbazole, pyrroloimidazole, pyrrolopyrrole, thiophenopyrrole, thiophenothiophene, furanopyrrole, furanofuran, thiophenofuran, benzisoxazole, benzisothiazole, benzimidazole, pyridine, pyrazine, pyridazine, pyrimidine, triazine, quinoline, isoquinoline, phthalazine, quinoxaline, phenanthridine, perimidine, quinazoline, and quinazolinone.

[0088] The term "heterocyclic group" means that at least one carbon atom in the cycloalkyl group is replaced by a non-carbon atom, and the non-carbon atom can be an N atom, an O atom, an S atom, etc., and it can be a saturated ring or a partially unsaturated ring. A phrase containing this term, for example, "C4~C9 heterocyclic group" means a heterocyclic group containing 4 to 9 carbon atoms, and each occurrence can be independently a C4 heteroalkyl group, a C6 heteroalkyl group, a C7 heteroalkyl group, a C8 heteroalkyl group, or a C9 heteroalkyl group. Suitable examples include, but are not limited to: dihydropyridyl, tetrahydropyridyl (piperidyl), tetrahydrothienyl, sulfoxidized tetrahydrothienyl, tetrahydrofuryl, tetrahydroquinolyl, tetrahydroisoquinolyl, dihydroindolyl.

[0089] The term "amino" means a derivative of ammonia and has the structural feature of the formula -N(X)2, where each "X" is independently H, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted heterocyclic group, etc. Non-limiting types of amino groups include -NH2, -N(alkyl)2, -NH(alkyl), -N(cycloalkyl)2, -NH(cycloalkyl), -N(heterocyclic group)2, -NH(heterocyclic group), -N(aryl)2, -NH(aryl), -N(alkyl)(aryl), -N(alkyl)(heterocyclic group), -N(cycloalkyl)(heterocyclic group), -N(aryl)(heteroaryl), -N(alkyl)(heteroaryl), etc.

[0090] The term "halo group" refers to F, Cl, Br or I.

[0091] The term "alkylene" refers to a hydrocarbon group formed by removing one hydrogen atom from an alkyl group, having two monovalent group centers, which can be a saturated branched alkyl group or a saturated straight-chain alkyl group. For example, "C1-C9 alkylene" means that the alkyl part contains 1-9 carbon atoms, and each occurrence can independently be C1 alkylene, C4 alkylene, C5 alkylene, C6 alkylene, C7 alkylene, C8 alkylene or C9 alkylene. Suitable examples include but are not limited to: methylene (-CH2-), 1,1-ethyl (-CH(CH3)-), 1,2-ethyl (-CH2CH2-), 1,1-propyl (-CH(CH2CH3)-), 1,2-propyl (-CH2CH(CH3)-), 1,3-propyl (-CH2CH2CH2-) and 1,4-butyl (-CH2CH2CH2CH2-).

[0092] The term "alkenylene" refers to a hydrocarbon group formed by removing one hydrogen atom from an alkenyl group, having two monovalent group centers, which can be an unsaturated branched hydrocarbon group or an unsaturated straight-chain hydrocarbon group. For example, "C2-C9 alkenylene" means that the alkenyl part contains 2-9 carbon atoms, and each occurrence can independently be C2 alkenylene, C4 alkenylene, C5 alkenylene, C6 alkenylene, C7 alkenylene, C8 alkenylene or C9 alkenylene. Suitable examples include but are not limited to: 1,2-vinyl (-CH=CH-).

[0093] The term "alkynylene" refers to a hydrocarbon group formed by removing one hydrogen atom from an alkynyl group, having two monovalent group centers, which can be an unsaturated branched hydrocarbon group or an unsaturated straight-chain hydrocarbon group. For example, "C2-C9 alkynylene" means that the alkynyl part contains 2-9 carbon atoms, and each occurrence can independently be C2 alkynylene, C4 alkynylene, C5 alkynylene, C6 alkynylene, C7 alkynylene, C8 alkynylene or C9 alkynylene. Suitable examples include but are not limited to: ethynylene (-C≡C-), propargyl (-CH2C≡C-) and 4-pentynyl (-CH2CH2CH2C≡C-).

[0094] The term "alkylamino" refers to an amino group substituted by at least one alkyl group. Suitable examples include but are not limited to: -NH2, -NH(CH3), -N(CH3)2, -NH(CH2CH3), -N(CH2CH3)2.

[0095] The term "arylalkyl" refers to a hydrocarbon group formed by replacing at least one hydrogen atom bonded to a carbon atom in an alkyl group with an aryl group. The aryl moiety may include 5 to 20 carbon atoms, and the alkyl moiety may include 1 to 9 carbon atoms. Suitable examples include, but are not limited to: benzyl, 2-phenyleth-1-yl, naphthylmethyl, 2-naphthyleth-1-yl, naphthobenzyl, and 2-naphthophenyleth-1-yl.

[0096] In the electrodes of a secondary battery, due to differences in potential and chemical properties between the positive and negative electrodes, there are differences in the requirements for the electrolyte. Therefore, it is necessary to provide different electrolytes for the positive and negative electrodes according to their different requirements for the electrolyte to improve the cycle performance of the battery. However, in a conventional electrode, the separator is a porous structure and does not block other components in the electrolyte except for the active ions. The other components in the electrolyte diffuse into each other, and it is impossible to achieve differentiation of the electrolyte between the positive and negative electrodes.

[0097] To solve the above technical problems, the present application provides a separator. By providing a filler including a polymer matrix, an electrolyte salt, and a plasticizer in the porous structure of the base film, the separator can effectively conduct active ions and improve the gas permeability and density of the separator. Thus, it can effectively block the mutual diffusion of other components in the electrolyte between the positive and negative electrodes, and reduce the performance deterioration caused by the mutual diffusion of by-products of the positive and negative electrodes to the other side.

[0098] In a first aspect, the present application provides a separator, including a base film and a filler disposed in the porous structure of the base film. The filler includes a polymer matrix, an electrolyte salt, and a plasticizer. The polymer matrix includes a copolymer of a first monomer unit and a second monomer unit; the first monomer unit includes at least one of an ethylenically unsaturated carbonate monomer unit, an ethylenically unsaturated sulfate monomer unit, an ethylenically unsaturated sulfonate monomer unit, an ethylenically unsaturated sulfone monomer unit, an ethylenically unsaturated carboxylate monomer, an ethylenically unsaturated phosphate monomer unit, an ethylenically unsaturated nitrile monomer unit, and an ethylenically unsaturated ether monomer unit, and the second monomer unit includes an acrylate monomer unit.

[0099] It should be noted that the "polymer matrix" in the present application is an interpenetrating crosslinked gel network structure. In the filler, the electrolyte salt is dispersed in the plasticizer, and the polymer matrix binds the plasticizer and the electrolyte salt dispersed in the plasticizer in the interpenetrating crosslinked gel network structure.

[0100] In the separator provided by the present application, the filler disposed in the porous structure of the base film includes a polymer matrix, an electrolyte salt, and a plasticizer. Among them, the polymer matrix has a relatively high density, can provide a high gas permeability for the separator, and the polymer matrix basically does not depolymerize during the traditional high-temperature formation process. At the same time, the electrolyte salt dispersed in the plasticizer contained in the filler can enhance the conductivity of the separator to active ions. Thus, the above-mentioned filler can enable the separator to have a high gas permeability and density while effectively conducting active ions, thereby effectively blocking the mutual diffusion between other components in the electrolyte between the positive and negative electrodes except for the active ions, reducing the performance deterioration caused by the mutual diffusion of the by-products of the positive and negative electrodes to the other side, and improving the cycle performance of the battery.

[0101] Among them, the selected first monomer unit contains an acrylate group cross-linking site, and the selected second monomer unit contains an olefinic bond cross-linking site. In this way, the first monomer unit and the second monomer unit can cross-link and polymerize through the acrylate group and the olefinic bond, so as to form a polymer matrix with an interpenetrating cross-linked network structure. The polymer matrix can solidify and bind the plasticizer and the electrolyte salt dispersed in the plasticizer in the interpenetrating cross-linked network structure to form a dense filler capable of conducting active ions. In addition, the selected first monomer unit contains a functional group, which is beneficial for the separator to be adapted to more application scenarios.

[0102] It should be noted that the "olefinically unsaturated carbonate monomer unit" referred to in the present application means a monomer unit that contains both a carbon-carbon double bond and a carbonate group.

[0103] In some embodiments, the olefinically unsaturated carbonate monomer unit includes the structure shown in formula (1): (1), in formula (1), M 11 includes, but is not limited to, one or more of alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic group, amino group, halogen group, alkylene group, alkenylene group, alkynylene group, alkylamino group, and arylalkyl group. * represents a bonding site, and the weight-average molecular weight of the monomer unit shown in formula (1) ≤ 500.

[0104] It should be noted that the "olefinically unsaturated sulfate monomer unit" referred to in the present application means a monomer unit that contains both a carbon-carbon double bond and a sulfate group.

[0105] In some embodiments, the olefinically unsaturated sulfate monomer unit includes the structure shown in formula (2): (2), in formula (2), M 21 includes, but is not limited to, one or more of alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic group, amino group, halogen group, alkylene group, alkenylene group, alkynylene group, alkylamino group, and arylalkyl group. * represents a bonding site, and the weight-average molecular weight of the monomer unit shown in formula (2) ≤ 500.

[0106] It should be noted that the "ethylenically unsaturated sulfonate monomer unit" described in this application refers to a monomer unit that simultaneously contains a carbon-carbon double bond and a sulfonate group.

[0107] In some embodiments, the ethylenically unsaturated sulfonate monomer unit includes the structure shown in formula (3): (3), in formula (3), M 31 includes but is not limited to one or more of alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic group, amino group, halogen group, alkylene group, alkenylene group, alkynylene group, alkylamino group, and arylalkyl group, * represents a bonding site, and the weight-average molecular weight of the monomer unit represented by formula (3) ≤ 500.

[0108] It should be noted that the "ethylenically unsaturated sulfone monomer unit" described in this application refers to a monomer unit that simultaneously contains a carbon-carbon double bond and a sulfate group.

[0109] In some embodiments, the ethylenically unsaturated sulfone monomer unit includes the structure shown in formula (4): (4), in formula (4), M 41 includes but is not limited to one or more of alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic group, amino group, halogen group, alkylene group, alkenylene group, alkynylene group, alkylamino group, and arylalkyl group, * represents a bonding site, and the weight-average molecular weight of the monomer unit represented by formula (4) ≤ 500.

[0110] It should be noted that the "ethylenically unsaturated carboxylate monomer unit" described in this application refers to a monomer unit that simultaneously contains a carbon-carbon double bond and a carboxylate group.

[0111] In some embodiments, the ethylenically unsaturated carboxylate monomer unit includes the structure shown in formula (5): (5), in formula (5), M 51 includes but is not limited to one or more of alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic group, amino group, halogen group, alkylene group, alkenylene group, alkynylene group, alkylamino group, and arylalkyl group, * represents a bonding site, and the weight-average molecular weight of the monomer unit represented by formula (5) ≤ 500.

[0112] It should be noted that the "ethylenically unsaturated phosphate monomer unit" described in this application refers to a monomer unit that simultaneously contains a carbon-carbon double bond and a phosphate group.

[0113] In some embodiments, the ethylenically unsaturated phosphate monomer unit includes the structure shown in formula (6): (6), in formula (6), M 61including but not limited to one or more of alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic group, amino group, halogen group, alkylene, alkenylene, alkynylene, alkylamino group, and arylalkyl group, * represents a bonding site, and the weight-average molecular weight of the monomer unit represented by formula (6) is ≤500.

[0114] It should be noted that the "ethylenically unsaturated nitrile monomer unit" described in this application refers to a monomer unit that simultaneously contains a carbon-carbon double bond and a cyano group.

[0115] In some embodiments, the ethylenically unsaturated nitrile monomer unit includes the structure shown in formula (7): (7), in formula (7), M 71 including but not limited to one or more of alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic group, amino group, halogen group, alkylene, alkenylene, alkynylene, alkylamino group, and arylalkyl group, * represents a bonding site, and the weight-average molecular weight of the monomer unit represented by formula (7) is ≤500.

[0116] It should be noted that the "ethylenically unsaturated ether monomer unit" described in this application refers to a monomer unit that simultaneously contains a carbon-carbon double bond and an ether bond.

[0117] In some embodiments, the ethylenically unsaturated ether monomer unit includes the structure shown in formula (8): (8), in formula (8), M 81 including but not limited to one or more of alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic group, amino group, halogen group, alkylene, alkenylene, alkynylene, alkylamino group, and arylalkyl group, * represents a bonding site, and the weight-average molecular weight of the monomer unit represented by formula (8) is ≤500.

[0118] It should be noted that the "acrylates" described in this application refers to the general term for acrylates and their derivatives.

[0119] In some embodiments, the acrylate monomer unit includes the structure shown in formula (9):

[0120] (9), in formula (9), R1 includes one or more of a hydrogen atom, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic group, amino group, halogen group, alkylene, alkenylene, alkynylene, alkylamino group, and arylalkyl group, * represents a bonding site, and the weight-average molecular weight of the monomer unit represented by formula (9) is ≤1000.

[0121] The acrylate monomer unit selected as the second monomer unit can provide the main reaction matrix for forming an interpenetrating cross-linked network structure, and the long-chain structure corresponding to its relatively high weight-average molecular weight can be matched with the short-chain structure corresponding to the relatively low weight-average molecular weight of the first monomer unit, so that the polymer matrix formed by the cross-linking reaction has a relatively high cross-linking degree and compactness; and it has good affinity and compatibility with the plasticizer, and can better bind the plasticizer and electrolyte salt in the formed polymer matrix.

[0122] In some embodiments, the number of acrylate groups contained in the acrylate monomer unit ≥ 2. In this way, the acrylate monomer has more cross-linking sites, which can improve the cross-linking degree of the formed polymer matrix, thereby facilitating the improvement of the compactness of the polymer matrix, and enabling the polymer matrix to better bind the plasticizer and electrolyte salt therein, so as to further improve the gas permeability and ionic conductivity of the separator membrane.

[0123] In some embodiments, based on the total mass of the polymer matrix, the mass percentage of the first monomer unit in the polymer matrix is 16% - 67%. For example, this mass percentage can be 16%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 67% or within the range composed of any of the above values.

[0124] In some embodiments, based on the total mass of the polymer matrix, the mass percentage of the first monomer unit in the polymer matrix is 16% - 35%. For example, this mass percentage can be 16%, 19%, 22%, 25%, 28%, 31%, 33%, 35% or within the range composed of any of the above values.

[0125] When the mass percentage of the first monomer unit in the polymer matrix is within this range, it is beneficial to further improve the gas permeability and ionic conductivity of the separator membrane.

[0126] In some embodiments, the polymer matrix further includes a homopolymer or copolymer of the first monomer unit.

[0127] When the polymer matrix further includes a homopolymer or copolymer of the first monomer unit, it is beneficial to further improve the compactness of the polymer matrix, thereby further improving the gas permeability of the separator membrane.

[0128] In some embodiments, the acrylate monomer units include one or more of ethylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, 1,4 - butanediol diacrylate, 1,4 - butanediol dimethacrylate, 1,3 - butanediol diacrylate, 1,3 - butanediol dimethacrylate, 1,6 - hexanediol diacrylate, 1,6 - hexanediol dimethacrylate, dipropylene glycol diacrylate, dipropylene glycol dimethacrylate, tripropylene glycol diacrylate, tripropylene glycol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, 2(propoxylated)neopentyl glycol diacrylate, polyethylene glycol diacrylate (PEGDA), polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, polycyclohexyl acrylate, methoxypolyethylene glycol acrylate, ethoxylated trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, methoxypolyethylene glycol methacrylate, pentaerythritol triacrylate, propoxylated glycerol triacrylate (GPTA), tris(2 - hydroxyethyl)isocyanurate triacrylate, bis(trimethylolpropane)tetraacrylate, pentaerythritol tetraacrylate, 4(ethoxy)pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate.

[0129] In some embodiments, the ethylenically unsaturated carbonate monomer units include one or more of vinylene carbonate (VC), ethylene ethylene carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, fluorinated ethylene carbonate, and chlorinated ethylene carbonate.

[0130] In some embodiments, the ethylenically unsaturated sulfate monomer units include one or more of ethylene vinyl sulfite, vinyl sulfite, 4 - methyl vinyl sulfate, and 4 - ethyl vinyl sulfate.

[0131] In some embodiments, the ethylenically unsaturated sulfonate monomer units include one or more of 1,3 - propanesultone, allyl p - toluenesulfonate, and 2,2 - difluoroethyl 4 - methylbenzenesulfonate.

[0132] In some embodiments, the ethylenically unsaturated phosphate monomer units include one or more of dimethyl vinyl phosphate, diethyl vinyl phosphate, diethyl propenyl phosphate, diethyl butenyl phosphate, diethyl 1 - buten - 2 - yl phosphonate, diethyl ethynyl phosphate, vinyl trifluoromethyl phosphate, vinyl - 1 - trifluoroethyl phosphate, diethyl fluorovinyl phosphate, and 1 - trifluoropropenyl ethyl phosphate.

[0133] In some embodiments, the ethylenically unsaturated carboxylic acid ester monomer unit includes vinyl acetate.

[0134] In some embodiments, the ethylenically unsaturated sulfone monomer unit includes one or more of methyl vinyl sulfone, ethyl vinyl sulfone, cyclobutene sulfone, sulfolane, and cycloethyl sulfoxide.

[0135] In some embodiments, the ethylenically unsaturated nitrile monomer unit includes one or more of acrylonitrile, succinonitrile, glutaronitrile, and adiponitrile.

[0136] In some embodiments, the ethylenically unsaturated ether monomer unit includes one or more of 1,3-dioxolane, ethylene oxide, 1,2-epoxypropane, 4-methyl-1,3-dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, ethylene glycol dimethyl ether, ethylene glycol diglycidyl ether, and triethylene glycol divinyl ether.

[0137] In some embodiments, the filler includes an electrolyte salt.

[0138] The electrolyte salt is beneficial to improving the ionic conductivity of the separator membrane, enabling active ions to effectively conduct between the positive and negative electrodes through the separator membrane.

[0139] In some embodiments, the electrolyte salt includes at least one of, but is not limited to, lithium salts and sodium salts.

[0140] In some embodiments, the lithium salt includes one or more of, but is not limited to, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorophosphate, lithium difluoro(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0141] In some embodiments, the sodium salt includes one or several of, but is not limited to, NaPF6, NaClO4, NaBCl4, NaSO3CF3, and Na(CH3)C6H4SO3.

[0142] In some embodiments, the filler includes a plasticizer.

[0143] The plasticizer can be used to dissolve and disperse the electrolyte salt, and the higher the content of the plasticizer, the more electrolyte salt is bound in the polymer matrix, and the better the performance of the separator membrane in conducting active ions.

[0144] In some embodiments, the plasticizer includes at least one of chain ester organic solvents, cyclic ester organic solvents, ether organic solvents, and sulfone organic solvents.

[0145] Selecting a plasticizer of the above type is beneficial to further improve the ionic conductivity of the separator, and is also beneficial to improving the toughness of the separator and its compatibility with the electrolyte, and improving its mechanical properties.

[0146] In some embodiments, the plasticizer includes, but is not limited to, one or more of ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, dimethyl sulfone, methyl ethyl sulfone or diethyl sulfone.

[0147] In some embodiments, the mass percentage of the polymer matrix in the filler is 10% - 50%, and can be optionally 15% - 35%. For example, the mass percentage of the polymer matrix in the filler can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50% or within the range composed of any of the above values.

[0148] When the mass percentage of the polymer matrix in the filler is within the above range, the separator can obtain a relatively high air permeability, enabling the separator to play a relatively high blocking role in the diffusion of other components in the electrolyte except for active ions between the positive and negative electrodes.

[0149] In some embodiments, the mass percentage of the electrolyte salt in the filler is 10% - 20%.

[0150] For example, the mass percentage of the electrolyte salt in the filler can be 10%, 12%, 14%, 16%, 18%, 20% or within the range composed of any of the above values. When the mass percentage of the electrolyte salt in the filler is within the above range, the separator can have a certain ionic conductivity, enabling active ions to better conduct between the positive and negative electrodes through the separator.

[0151] In some embodiments, the mass percentage of the plasticizer in the filler is 40% - 70%.

[0152] For example, the mass percentage of the plasticizer in the filler can be 40%, 45%, 50%, 55%, 60%, 65%, 70% or within the range composed of any of the above values. When the mass percentage of the plasticizer in the filler is within the above range, it is beneficial to further improve the ionic conductivity of the separator and is beneficial to reducing its impact on the air permeability of the separator.

[0153] In some embodiments, the separator further includes the filler disposed on at least a part of the surface of the base film.

[0154] Fillers are provided on at least part of the surface of the base film, which is beneficial to further improving the air permeability of the separator membrane, thereby further enhancing the blocking effect of the separator membrane on the diffusion of other components in the electrolyte except for active ions between the positive and negative electrodes, and further improving the cycling performance of the battery.

[0155] In some embodiments, the separator membrane further includes an inorganic coating provided on at least one surface of the base film, and the inorganic coating includes inorganic particles.

[0156] The setting of the inorganic coating is beneficial to enhancing the affinity between the base film and the composition forming the filler, improving the liquid absorption capacity of the base film, so that the porous structure of the base film is completely infiltrated by the composition, thereby improving the filling degree of the filler in the porous structure of the base film, and further improving the air permeability of the separator membrane and its blocking performance against the mutual diffusion of other components in the electrolyte except for active ions.

[0157] In some embodiments, the filler is provided inside the inorganic coating and / or on at least part of the surface of the inorganic coating.

[0158] The setting of the filler inside the inorganic coating is beneficial to improving the density of the inorganic coating, thereby further improving the air permeability of the separator membrane and its blocking performance against the mutual diffusion of other components in the electrolyte except for active ions. The setting of the filler on at least part of the surface of the inorganic coating is beneficial to further improving the air permeability of the separator membrane and further improving the cycling performance of the battery.

[0159] In some embodiments, the inorganic coating contains a binder, and the inorganic particles are connected by the binder. The binder can reduce the shedding of the inorganic particles and improve the structural stability of the inorganic coating, thereby improving the structural stability of the separator membrane.

[0160] In some embodiments, the mass ratio of the inorganic particles in the inorganic coating is 90% - 97%. For example, the mass ratio of the inorganic particles in the inorganic coating can be 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97% or within any range composed of the above values. The mass ratio of the inorganic particles in the inorganic coating within this range is beneficial to further improving the air permeability of the separator membrane and its blocking performance against the mutual diffusion of other components in the electrolyte except for active ions.

[0161] In some embodiments, the mass ratio of the binder in the inorganic coating is 3% - 10%. For example, the mass ratio of the binder in the inorganic coating can be 3%, 5%, 7%, 9%, 10% or within any range composed of the above values. The mass ratio of the binder in the inorganic coating within this range is beneficial to further improving the structural stability of the separator membrane.

[0162] In some embodiments, the thickness of the inorganic coating is 3 μm to 5 μm. When the thickness of the inorganic coating is within this range, while improving the air permeability of the separator membrane, it can also enable active ions to conduct between the positive and negative electrodes through the separator membrane.

[0163] In some embodiments, the inorganic particles include but are not limited to at least one of alumina, boehmite, titanium oxide, or zirconium oxide.

[0164] In some embodiments, the volume average particle size D V 50 of the inorganic particles is 50 nm to 200 nm. For example, the volume average particle size D V 50 of the inorganic particles can be 50 nm, 80 nm, 120 nm, 150 nm, 180 nm, 200 nm or within the range composed of any of the above values.

[0165] The volume average particle size D of the inorganic particles V 50 has the meaning well-known in the art and can be tested by methods known in the art. For example, referring to GB / T 19077-2016 Laser Diffraction Method for Particle Size Distribution, it can be measured using a laser particle size analyzer (such as the Mastersizer 2000E type laser particle size analyzer of Malvern Instruments Limited, UK).

[0166] In some embodiments, the binder includes but is not limited to one or more of polyvinylidene fluoride, polytetrafluoroethylene, or sodium carboxymethyl cellulose.

[0167] In some embodiments, the base film includes at least one of a polyolefin-based film, a polyvinyl fluoride-based film, a cellulose-containing nanofiber-based film, or a polyimide-based film.

[0168] For example, the base film includes but is not limited to at least one of polyethylene, polypropylene, or polyimide.

[0169] In some embodiments, the air permeability AP of the separator membrane satisfies: AP ≥ 20000 s / 100 mL, and the ionic conductivity λ of the separator membrane satisfies: λ ≥ 0.1 mS / cm.

[0170] When the air permeability of the separator membrane meets the above range, it can effectively enhance the blocking effect of the separator membrane on the mutual diffusion of other components in the electrolyte except for the active ions. When different electrolytes are used for the positive electrode and the negative electrode respectively, it can effectively reduce the mutual diffusion and mixing of other components in the positive electrode electrolyte except for the active ions and other components in the negative electrode electrolyte except for the active ions, thereby reducing the performance deterioration caused by the mutual diffusion of the by-products of the positive and negative electrodes to the other side, and improving the cycle performance of the battery. At the same time, when the ionic conductivity λ of the separator membrane meets the above range, it can enhance its conduction effect on the active ions, and further improve the cycle performance of the battery.

[0171] In some embodiments, the air permeability of the separator membrane satisfies: 31000 s / 100 mL ≤ AP ≤ 50100 s / 100 mL. For example, AP can be 31000 s / 100 mL, 33000 s / 100 mL, 35000 s / 100 mL, 37000 s / 100 mL, 40000 s / 100 mL, 45000 s / 100 mL, 50000 s / 100 mL, 50100 s / 100 mL or within the range composed of any of the above values. When the air permeability AP of the separator membrane is within this range, it is beneficial to further enhance the blocking effect of the separator membrane on the mutual diffusion of other components in the electrolyte except for the active ions, and further improve the cycle performance of the battery.

[0172] In some embodiments, the ionic conductivity λ of the separator membrane satisfies: 0.2 mS / cm ≤ λ < 0.6 mS / cm. For example, λ can be 0.2 mS / cm, 0.4 mS / cm, 0.45 mS / cm, 0.5 mS / cm, 0.55 mS / cm, 0.6 mS / cm or within the range composed of any of the above values. When the ionic conductivity λ of the separator membrane is within this range, it is beneficial to further enhance the conduction effect of the separator membrane on the active ions.

[0173] The air permeability of the separator membrane has the meaning well-known in the art. The air permeability of the separator membrane is comprehensively affected by the internal pore structure such as the porosity, pore size, pore shape and pore tortuosity of the separator membrane, and reflects the degree of barrier of the separator membrane to other components in the electrolytes on both sides except for the active ions. It can be tested by methods known in the art. For example, the separator membrane is punched into small round pieces with a diameter of 50 mm, and the air permeability of the small round pieces is tested by using a Wangyan type air permeability meter (Asahi Seiko model EG01-55-1MR). The test pressure is controlled at 1.21 kPa, and the time (seconds, s) required for passing 100 mL of gas (air) is measured, that is, the air permeability of the separator membrane is obtained, and the unit is s / 100 mL.

[0174] The ionic conductivity of the separator refers to the ability of the separator to conduct active ions, and can be tested by the following method. The separator is punched into small round pieces with a diameter of 16 mm, the thickness d is measured and recorded. The punched small round pieces are assembled in the order of stainless steel sheet, separator, and stainless steel sheet, and at the same time, a small amount (10 μL) of electrolyte (the solvent is EC:EMC with a volume ratio of 3:7, and the lithium salt is 1 mol / L LiPF6) is dropped and encapsulated in a coin cell. The encapsulation pressure is 500 psi. The electrochemical impedance spectroscopy of a Solartron 1470E CellTest multi-channel electrochemical workstation is used for testing. The test temperature is 25 °C, without additional pressure. The test voltage can be 10 mV, and the test frequency can be 0.1 Hz to 100 K Hz. A Nyquist plot is drawn. The Zview software is used to analyze the obtained Nyquist plot by the equivalent circuit curve fitting method. The intersection point of the straight line and the horizontal axis is denoted as R. The ionic conductivity is calculated using the formula λ = d / RS; where λ represents the ionic conductivity, d represents the thickness of the separator, R represents the ionic resistance, and S represents the cross-sectional area of the small round piece.

[0175] In some embodiments, the thickness of the separator is 5 μm to 50 μm. For example, the thickness of the separator can be 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm or within the range composed of any of the above values. When the thickness of the separator is within this range, while conducting active ions, it can also reduce the occurrence of micro-short circuits between the positive and negative electrodes.

[0176] The thickness of the separator has the meaning well-known in the art and can be tested by methods known in the art. For example, a micrometer (Mitutoyo, MDH-25MC) can be used to test the thickness of the separator.

[0177] In a second aspect, a method for preparing a separator according to the present application can be used to prepare the separator of the first aspect of the present application, and it can include the following steps:

[0178] S1. Perform in-situ polymerization treatment on a base film containing a composition to obtain a separator, where the composition includes a first monomer unit, a second monomer unit, an electrolyte salt, and a plasticizer. The first monomer unit includes at least one of an ethylenically unsaturated carbonate monomer unit, an ethylenically unsaturated sulfate monomer unit, an ethylenically unsaturated sulfonate monomer unit, an ethylenically unsaturated sulfone monomer unit, an ethylenically unsaturated carboxylate monomer, an ethylenically unsaturated phosphate monomer unit, an ethylenically unsaturated nitrile monomer unit, and an ethylenically unsaturated ether monomer unit. The second monomer unit includes an acrylate monomer unit.

[0179] This application forms a separator membrane by means of in-situ polymerization. In-situ polymerization means that under the stimulation of external conditions, polymerization between a first monomer unit and a second monomer unit is initiated by an initiator to form a polymer. This method has almost no solvent volatilization during the preparation process, has relatively low condition requirements, and is easy to prepare.

[0180] In some embodiments, the in-situ polymerization treatment of the base film containing the composition in step S1 above may include the following steps:

[0181] S10. Make the composition enter the porous structure of the base film;

[0182] S20. Initiate in-situ polymerization of the first monomer unit and the second monomer unit to form a polymer matrix, and the plasticizer and the electrolyte salt dispersed in the plasticizer are bound in the polymer matrix to form a filler.

[0183] Through the above steps S10 - S20, a polymer matrix and a filler can be formed in-situ in the porous structure of the base film. This filler has relatively high density and can improve the gas permeability of the separator membrane.

[0184] It can be understood that before step S10, the composition can be first coated on at least one side of the base film, and then under the action of its own gravity or capillary action, the composition gradually penetrates into the porous structure of the base film; then in-situ polymerization of the first monomer unit and the second monomer unit is initiated, and a polymer matrix and a filler can be formed in the porous structure of the base film, and optionally a polymer matrix and a filler can also be formed on at least part of the surface of the base film to obtain the separator membrane described in the first aspect of this application.

[0185] In some embodiments, there is no particular limitation on the method of coating the composition. For example, it can be blade coating, gravure coating, slot die coating, dip coating or spraying, etc.

[0186] In some embodiments, the first monomer unit and the second monomer unit correspond to the first monomer unit and the second monomer unit described in the first aspect of this application, which will not be elaborated here.

[0187] In some embodiments, the mass ratio of the first monomer unit and the second monomer unit in the composition is 10% - 50%.

[0188] In some embodiments, the composition further contains the electrolyte salt and the plasticizer. The electrolyte salt and the plasticizer are the same as those described in the first aspect of this application, which will not be elaborated here.

[0189] It should be noted that the above "polymer matrix" is a crosslinked gel material, and during the in-situ polymerization process, the polymer matrix will bind the electrolyte salt and the plasticizer in the gel network structure to form a filler.

[0190] The electrolyte salt can improve the ionic conductivity of the filler; during the in-situ polymerization process, the plasticizer is beneficial to improving the dissolution and dispersion of the electrolyte salt in the composition, so that the formed polymer matrix can bind more electrolyte salts, thereby further improving the ionic conductivity of the filler.

[0191] In some embodiments, the mass percentage of the electrolyte salt in the composition is 10% - 20%.

[0192] In some embodiments, the mass percentage of the plasticizer in the composition is 40% - 70%.

[0193] In some embodiments, the composition further comprises a thickener and / or an initiator.

[0194] The thickener can adjust the viscosity of the composition, so that after the composition is coated on the base film, it can penetrate into the interior of the base film and fill the porous structure of the base film within a suitable time, making the polymer matrix and filler after in-situ polymerization disperse relatively uniformly in the porous structure of the base film, and at the same time, it will not be unable to adsorb in the base film due to too low viscosity. The initiator can be used to initiate the in-situ polymerization reaction.

[0195] In some embodiments, the mass percentage of the thickener in the composition is 0.1% - 0.5%. For example, the mass percentage of the thickener in the composition can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5% or within the range composed of any of the above values. When the mass percentage of the thickener in the composition is within the above range, while improving the dispersibility of the polymer matrix and filler in the base film, it can also effectively adsorb them in the base film.

[0196] It should be noted that during the in-situ polymerization reaction process, the thickener contained in the composition does not participate in the reaction. After the polymer matrix and filler are formed by the reaction, the thickener will be bound in the gel network structure of the polymer matrix together with the electrolyte salt and the plasticizer.

[0197] In some embodiments, the thickener includes, but is not limited to, one or more of polyvinyl formal, polyvinylidene fluoride and its copolymers, polyvinylidene fluoride, polyvinylidene fluoride, trichloroethylene, polytetrafluoroethylene, acrylic acid glue, epoxy resin, polyethylene oxide, polyacrylonitrile, sodium carboxymethyl cellulose, styrene-butadiene rubber, polymethyl acrylate, polymethyl methacrylate, polyacrylamide, polyvinylpyrrolidone.

[0198] In some embodiments, based on the total mass of the first monomer unit and the second monomer unit in the composition, the mass percentage of the initiator is 1% - 10%.

[0199] In some embodiments, the initiator includes at least one of a peroxide initiator, a persulfate initiator, or an azo initiator.

[0200] In some embodiments, the initiator includes one or more of, but is not limited to, benzoyl peroxide, lauroyl peroxide, ammonium persulfate, azobisisobutyronitrile (AIBN), or azodiisovaleronitrile.

[0201] In some embodiments, the method for initiating the in-situ polymerization of the first monomer unit and the second monomer unit includes one of electron beam initiation, ultraviolet light initiation, and thermal initiation.

[0202] It can be understood that the above electron beam initiation, ultraviolet light initiation, and thermal initiation are all conventional in-situ polymerization initiation methods, and the initiation conditions corresponding to various initiation methods can be adjusted according to actual preparation requirements, which will not be elaborated here.

[0203] In some embodiments, the following steps may further be included: S10': forming an inorganic coating on at least one side of the base film.

[0204] The setting of the inorganic coating is beneficial to enhancing the affinity between the base film and the composition, improving the liquid absorption capacity of the base film, so that the porous structure inside the base film is completely infiltrated by the composition, thereby improving the filling degree of the polymer matrix and the filler in the porous structure of the base film.

[0205] In some embodiments, before step S10', an inorganic slurry for forming the inorganic coating may be coated on at least one side of the base film, and then dried to form the inorganic coating.

[0206] It can be understood that the inorganic coating may be formed before step S10. After forming the inorganic coating, the composition may be coated on at least one surface of the inorganic coating. Since there are gaps between the inorganic particles of the inorganic coating, the composition can enter the gaps of the inorganic coating under the action of its own gravity or capillary action, and penetrate through the inorganic coating into the porous structure of the base film. Then, in-situ polymerization of the monomers is initiated, and a polymer matrix and a filler can be formed in the voids of the inorganic coating and the porous structure of the base film, obtaining the separator membrane described in the first aspect of the present application.

[0207] In some embodiments, the inorganic slurry contains inorganic particles and a binder.

[0208] In some embodiments, the mass percentage of the inorganic particles in the inorganic slurry is 90% - 97%.

[0209] In some embodiments, the mass percentage of the binder in the inorganic slurry is 3% - 10%.

[0210] In some embodiments, the inorganic particles include, but are not limited to, at least one of alumina, boehmite, titanium oxide, and zirconia.

[0211] In some embodiments, the volume-average particle size D V 50 of the inorganic particles is 50 nm to 200 nm.

[0212] In some embodiments, the binder includes, but is not limited to, one or more of polyvinylidene fluoride, polytetrafluoroethylene, and sodium carboxymethyl cellulose.

[0213] Secondary battery

[0214] In addition, the secondary battery and the electrical device of the present application will be described below with appropriate reference to the accompanying drawings.

[0215] Generally, a secondary battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. During the charge and discharge process of the battery, active ions are inserted and extracted back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte functions to conduct ions between the positive electrode sheet and the negative electrode sheet. The separator is disposed between the positive electrode sheet and the negative electrode sheet, mainly functioning to prevent short circuit between the positive and negative electrodes, and at the same time allowing ions to pass through.

[0216] Positive electrode sheet

[0217] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer provided on at least one surface of the positive electrode current collector, and the positive electrode active material layer includes a positive electrode active material.

[0218] As a non-limiting example, the positive electrode current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode active material layer is provided on either or both of the two opposite surfaces of the positive electrode current collector.

[0219] In some of these embodiments, the positive electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, aluminum foil can be used. The composite current collector can 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 can be obtained by forming a metal material on a polymer material substrate. In the positive electrode current collector, non-limiting examples of the metal material can include one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc. In the positive electrode current collector, non-limiting examples of the polymer material substrate can include one or more of substrates such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0220] In some of these embodiments, the positive electrode active material may be a positive electrode active material for batteries known in the art. As a non-limiting example, the positive electrode active material may include one or more of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their modified compounds, etc. Non-limiting examples of lithium-containing phosphates with an olivine structure may include, but are not limited to, lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite material of lithium manganese iron phosphate and carbon, etc. Non-limiting examples of lithium cobalt oxide may include LiCoO2; non-limiting examples of lithium nickel oxide may include LiNiO2; non-limiting examples of lithium manganese oxide may include LiMnO2, LiMn2O4, etc.; non-limiting examples of lithium nickel cobalt manganese oxide may include LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which may also be abbreviated as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which may also be abbreviated as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (which may also be abbreviated as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (which may also be abbreviated as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (which may also be abbreviated as NCM 811 ), etc. Non-limiting examples of lithium nickel cobalt aluminum oxide may include LiNi 0.85 Co 0.15 Al 0.05 O2.

[0221] Understandably, during the charge and discharge process of the battery, the insertion and extraction as well as consumption of lithium (Li) will occur, and the content of Li in the positive electrode sheet is different when the battery is discharged to different states. In the listing of the positive electrode materials in this application, unless otherwise specified, the content of Li is the initial state of the material. When the positive electrode material is applied to the positive electrode sheet in the battery system, after charge and discharge cycles, the content of Li in the positive electrode material contained in the sheet usually changes. Among them, the content of Li can be measured by molar content, but is not limited thereto. Regarding "the content of Li is the initial state of the material", the initial state of the material refers to the state before being fed into the positive electrode slurry. It can be understood that new materials obtained by appropriately modifying the listed positive electrode materials are also within the scope of positive electrode materials. The aforementioned appropriate modification refers to acceptable modification methods for positive electrode materials, and non-limiting examples include coating modification.

[0222] In the listing of the positive electrode materials in this application, the content of oxygen (O) is only the theoretical state value, and the release of oxygen from the crystal lattice will cause the molar content of oxygen to change, and the actual content of O will show fluctuations. Among them, the content of O can be measured by molar content, but is not limited thereto.

[0223] In some embodiments, the positive electrode active material may also include at least one of the following materials: sodium transition metal oxides, polyanionic compounds, and Prussian blue compounds. However, this application is not limited to these materials, and other conventionally well-known materials that can be used as positive electrode active materials for sodium ion batteries can also be used.

[0224] As an optional technical solution of this application, in the sodium transition metal oxide, the transition metal may include one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. A non-limiting example of the sodium transition metal oxide may be Na x MO2, where M may include one or several of Ti, V, Mn, Co, Ni, Fe, Cr, and Cu, and 0 < x ≤ 1.

[0225] As an optional technical solution of this application, the polyanionic compound may be a type of compound having sodium ions, transition metal ions, and tetrahedral (YO4) n- anion units. The transition metal may include one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y may be one or more of P, S, and Si; n represents the valence state of (YO4) n-

[0226] The polyanionic compound may also be a compound having sodium ions, transition metal ions, tetrahedral (YO4) n- ​A class of compounds containing anionic units and halogen anions. The transition metal can include one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be one or more of P, S, and Si, and n represents the valence state of (YO4) n- ; the halogen can be one or more of F, Cl, and Br.

[0227] The polyanionic compound can also be a class of compounds having sodium ions, tetrahedral (YO4) n- anionic units, polyhedral units (ZO y ) m+ and optionally halogen anions. Y can be one or more of P, S, and Si, and n represents the valence state of (YO4) n- ; Z represents a transition metal, which can include one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, and m represents the valence state of (ZO y ) m+ ; the halogen can be one or more of F, Cl, and Br.

[0228] The polyanionic compounds can include one or more of NaFePO4, Na3V2(PO4)3 (sodium vanadium phosphate, abbreviated as NVP), Na4Fe3(PO4)2(P2O7), NaM’PO4F, and Na3(VO y )2(PO4)2F 3-2y (0 ≤ y ≤ 1). Among them, M’ in NaM’PO4F can include one or more of V, Fe, Mn, and Ni.

[0229] Prussian blue compounds can be a class of compounds having sodium ions, transition metal ions, and cyanide ions (CN - ). The transition metal can include one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. Non-limiting examples of Prussian blue compounds can be Na a Me b Me’ c (CN)6, where Me and Me’ can each independently be one or more of Ni, Cu, Fe, Mn, Co, and Zn, 0 < a ≤ 2, 0 < b < 1, 0 < c < 1.

[0230] In some of these embodiments, the positive electrode active material layer may also optionally include a binder. As a non-limiting example, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0231] In some of these embodiments, the positive electrode active material layer may also optionally include a conductive agent. As a non-limiting example, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0232] In some of these embodiments, the positive electrode sheet can be prepared by the following method: dispersing the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent to form a positive electrode slurry; coating the positive electrode slurry on at least one surface of the positive electrode current collector, and after processes such as drying and cold pressing, the positive electrode sheet can be obtained. The type of the solvent can be selected from, but not limited to, any one of the foregoing embodiments, such as N-methylpyrrolidone (NMP). The surface of the positive electrode current collector on which the positive electrode slurry is coated can be a single surface of the positive electrode current collector or two surfaces of the positive electrode current collector. The solid content of the positive electrode slurry can be 40wt% - 80wt%. The viscosity of the positive electrode slurry at room temperature can be adjusted to 5000 - 25000 mPa·s. When coating the positive electrode slurry, the coating unit surface density in terms of dry weight (deducting the solvent) can be 15 - 35 mg / cm 2 . The tap density of the positive electrode sheet can be 3.0 - 3.6 g / cm 3 , and can be optionally 3.3 - 3.5 g / cm 3 .

[0233] Negative electrode sheet

[0234] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer provided on at least one surface of the negative electrode current collector, and the negative electrode active material layer includes a negative electrode active material.

[0235] As a non-limiting example, the negative electrode current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode active material layer is provided on any one or both of the two opposite surfaces of the negative electrode current collector.

[0236] In some of these embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, a copper foil may be used. 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 substrate. The composite current collector may be obtained by forming a metal material on the polymer material substrate. In the negative electrode current collector, non-limiting examples of the metal material may include one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc. In the negative electrode current collector, non-limiting examples of the polymer material substrate may include one or more of substrates such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0237] In some of these embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As non-limiting examples, the negative electrode active material may include one or more of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based materials may include one or more of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based materials may include one or more of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as the negative electrode active material of the battery may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0238] In some of these embodiments, the negative electrode active material layer may also optionally include a binder. The binder may include one or more of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0239] In some of these embodiments, the negative electrode active material layer may also optionally include a conductive agent. The conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0240] In some of these embodiments, the negative electrode active material layer may also optionally include other additives, such as thickeners (such as sodium carboxymethyl cellulose (CMC-Na)), etc.

[0241] In some embodiments, the negative electrode sheet can be prepared in the following manner: dispersing the above-mentioned components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder, and any other components, in a solvent (a non-limiting example of the solvent is deionized water) to form a negative electrode slurry; coating the negative electrode slurry on at least one surface of the negative electrode current collector, and after processes such as drying and cold pressing, the negative electrode sheet can be obtained. The surface of the negative electrode current collector coated with the negative electrode slurry can be a single surface of the negative electrode current collector or two surfaces of the negative electrode current collector. The solid content of the negative electrode slurry can be 40wt% - 60wt%. The viscosity of the negative electrode slurry at room temperature can be adjusted to 2000 - 10000 mPa·s. When coating the negative electrode slurry, the coating unit surface density in terms of dry weight (deducting the solvent) can be 75 - 220 g / m 2 . The tap density of the negative electrode sheet can be 1.0 g / cm 3 ~1.8 g / cm 3 .

[0242] Electrolyte

[0243] The electrolyte functions to conduct ions between the positive electrode sheet and the negative electrode sheet, and the electrolyte includes a first electrolyte and a second electrolyte.

[0244] The present application does not particularly limit the type of the electrolyte, and it can be selected according to requirements. For example, the electrolyte can be liquid, gel-like, or all-solid-state.

[0245] In some embodiments, the battery includes a first electrolyte disposed between the positive electrode sheet and the separator, and a second electrolyte disposed between the negative electrode sheet and the separator.

[0246] In some embodiments, the composition of the first electrolyte is different from that of the second electrolyte.

[0247] In some embodiments, the content of the first electrolyte is different from that of the second electrolyte.

[0248] It can be understood that the composition of the first electrolyte being different from that of the second electrolyte means that the composition of the first electrolyte is different from that of the second electrolyte, but their contents can be the same or different.

[0249] It can be understood that the content of the first electrolyte being different from that of the second electrolyte means that the content of the first electrolyte is different from that of the second electrolyte, but their components can be the same or different.

[0250] In some of these embodiments, the electrolyte uses an electrolytic solution. The electrolytic solution includes an electrolyte salt and a solvent.

[0251] In some of these embodiments, the electrolyte salt may include one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorophosphate (LiPO2F2), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluoro bis(oxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP).

[0252] In some of these embodiments, the solvent may include ethylene carbonate (EC, ), propylene carbonate (PC, ), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butenyl carbonate ( ), fluoroethylene carbonate (FEC), methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone, or one or more of them.

[0253] In some of these embodiments, the electrolyte may also optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performances, such as additives for improving the overcharge performance of the battery, additives for improving the high-temperature or low-temperature performance of the battery, etc.

[0254] In some embodiments, the additives in the electrolyte may include, but are not limited to, one or more of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethyl carbonate (TFPC), etc.

[0255] Separator

[0256] In some of these embodiments, the secondary battery further includes a separator. The separator is the separator of the first aspect of the present application or the separator prepared by the method of the second aspect of the present application.

[0257] In some of these embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be made into an electrode assembly by a winding process or a stacking process.

[0258] In some of these embodiments, the secondary battery may include an outer package. The outer package can be used to encapsulate the above electrode assembly and electrolyte.

[0259] In some of these embodiments, the outer packaging of the secondary battery can be a hard case, such as a hard plastic case, an aluminum case, a steel case, etc. The outer packaging of the secondary battery can also be a soft package, such as a pouch soft package. The material of the soft package can be plastic. Further, non-limiting examples of the plastic can include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate, etc.

[0260] The secondary battery includes at least one battery cell. The secondary battery can include one or more battery cells.

[0261] In this application, unless otherwise specified, a "battery cell" refers to a basic unit capable of converting chemical energy and electrical energy into each other. Further, generally, it includes at least a positive electrode plate, a negative electrode plate, and an electrolyte. During the charge and discharge process of the battery, active ions are embedded and removed back and forth between the positive electrode plate and the negative electrode plate. The electrolyte plays a role in conducting active ions between the positive electrode plate and the negative electrode plate.

[0262] This application has no particular limitation on the shape of the battery cell, and it can be cylindrical, square, or any other arbitrary shape. For example, Figure 1 is a battery cell 5 with a square structure as an example.

[0263] In some of these embodiments, referring to Figure 2 , the outer packaging can include a housing 51 and a cover plate 53. Among them, the housing 51 can include a bottom plate and side plates connected to the bottom plate. The bottom plate and the side plates enclose to form a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode plate, the negative electrode plate, and the separator can be formed into an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. The number of electrode assemblies 52 included in the battery cell 5 can be one or more, and those skilled in the art can select according to actual needs.

[0264] The secondary battery can be a battery module 4 or a battery pack 1.

[0265] The battery module includes at least one battery cell. The number of battery cells included in the battery module can be one or more, and those skilled in the art can select a suitable number according to the application and capacity of the battery module.

[0266] Figure 3 is a battery module 4 as an example. Referring to Figure 3 , in the battery module 4, multiple battery cells 5 can be arranged in sequence along the length direction of the battery module 4. Of course, they can also be arranged in any other arbitrary manner. Further, the multiple battery cells 5 can be fixed by fasteners.

[0267] Optionally, the battery module 4 may further include a housing having an accommodation space, and a plurality of battery cells 5 are accommodated in the accommodation space.

[0268] In some embodiments, the above battery modules may also be assembled into a battery pack. The number of battery modules included in the battery pack may be one or more, and those skilled in the art can select a suitable number according to the application and capacity of the battery pack.

[0269] Figure 4 and Figure 5 is the battery pack 1 as an example. Refer to Figure 4 and Figure 5 , in the battery pack 1, a battery box and a plurality of battery modules 4 provided in the battery box may be included. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0270] In addition, the present application also provides an electrical device, and the electrical device includes the secondary battery provided by the present application. The secondary battery can be used as the power source of the electrical device or as the energy storage unit of the electrical device. The electrical device may include mobile devices, electric vehicles, electric trains, ships, satellites, energy storage systems, etc., but is not limited thereto. Among them, the mobile device may be, for example, a mobile phone, a laptop computer, etc.; the electric vehicle may be, for example, a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc., but is not limited thereto.

[0271] As the electrical device, the secondary battery can be selected according to its usage requirements.

[0272] Figure 6 is the electrical device 6 as an example. The electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the high power and high energy density requirements of the electrical device for the secondary battery, a battery pack or a battery module can be adopted.

[0273] Another example of the device may be a mobile phone, a tablet computer, a laptop computer, etc. This device usually requires thinning, and a secondary battery can be used as the power source.

[0274] Embodiment

[0275] Hereinafter, embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application and should not be construed as a limitation to the present application. For those not specified in the embodiments in terms of technology or conditions, the technology or conditions described in the literature in the art or according to the product specification are followed. For the reagents or instruments not specified in the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0276] Example 1

[0277] (1) Preparation of the positive electrode sheet

[0278] The positive electrode active material LiMn2O4, the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) were thoroughly stirred and mixed evenly in an N-methylpyrrolidone solvent at a weight ratio of 95:3:2, and then coated on both sides of the aluminum foil. After drying and cold pressing, a positive electrode sheet was obtained, where the coating amount per unit area on both sides was 0.27 g / 1540.25 mm 2 .

[0279] (2) Preparation of the negative electrode sheet

[0280] Graphite, conductive carbon, and styrene-butadiene rubber (SBR) were dissolved in deionized water and mixed at a weight ratio of 95:3:2 to obtain a negative electrode slurry under the action of a vacuum mixer; the negative electrode slurry was evenly coated on both sides of the copper foil; the copper foil was air-dried at room temperature and then transferred to an oven at 120 °C for drying for 1 h, and then obtained a negative electrode sheet through cold pressing and slitting, where the coating amount per unit area on both sides was 0.17 g / 1540.25 mm 2 .

[0281] (3) Separator

[0282] The composition was prepared according to the formula in Table 1, and then a PE-based film (thickness 12 μm, width 60 mm) was immersed in the composition (immersion time 1 min); then it was taken out and placed in an oven and heated at 80 °C (thermal initiation, time 1 h) to obtain a separator. In the plasticizer, EMC:EC = 1:1 (volume ratio).

[0283] (4) Preparation of the electrolyte

[0284] In a glove box with an argon atmosphere where the water content was <10 ppm, the fully dried lithium salt LiFSi was dissolved in an organic solvent and mixed evenly to obtain an electrolyte. Among them, the concentration of the lithium salt was 1 mol / L. The organic solvent was a mixed solution containing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC), where the volume ratio of EC, EMC, and DEC was 1:1:1.

[0285] (5) Preparation of the battery

[0286] The positive electrode sheet, the separator, and the negative electrode sheet were stacked in sequence and placed in an aluminum-plastic film layer by layer. The separator was placed between the positive and negative electrode sheets to play a role in isolation. The electrolyte was injected between the positive electrode sheet and the separator and between the negative electrode sheet and the separator to obtain a battery cell. Each battery cell was injected with 0.5 g of liquid, sealed, and after processes such as standing, hot and cold pressing, formation, clamping, and grading, a battery was obtained.

[0287] Examples 2 to 17

[0288] The preparation of the separator membranes and batteries in Examples 2 to 17 was similar to that in Example 1, except that: the preparation conditions and parameters of the separator membranes were adjusted, as detailed in Table 1 below; where EA is ethyl acetate, MSM is dimethyl sulfone, DEGME is diethylene glycol dimethyl ether, and AIBN is azobisisobutyronitrile.

[0289] Comparative Example 1

[0290] The preparation of the separator membranes and batteries was similar to that in Example 1, except that: when preparing the separator membranes, poly(ethylene glycol) diacrylate with the same mass ratio as in Example 1 was used to replace propoxylated glycerol triacrylate in Example 1, and at the same time, poly(ethylene glycol) diacrylate with the same mass ratio as in Example 1 was used to replace vinylene carbonate in Example 1.

[0291] Comparative Example 2

[0292] A polyethylene separator membrane (PE) with the same thickness was used to replace the separator membrane in Example 1.

[0293] In the above examples and comparative examples, the weight-average molecular weight of the poly(ethylene glycol) dimethacrylate used was 550, and the weight-average molecular weight of the poly(ethylene glycol) diacrylate used was 400.

[0294] Table 1

[0295]

[0296] In addition, the separator membranes and batteries obtained in Examples 1 to 17 and Comparative Examples 1 to 2 above were subjected to performance tests, and the test results are shown in Table 2 below.

[0297] Test section

[0298] (1) Cycle life test

[0299] The batteries prepared above were subjected to a cycle life test in a constant-temperature environment at 45°C. The process was as follows: stand still for 5 min, discharge at 0.5 C (72 mA) to 3 V, stand still for 5 min, then charge at 1 / 3 C to 4.3 V, and then perform constant-voltage charging at 4.3 V until the current ≤ 0.05 mA, stand still for 5 min, and then discharge at 1 / 3 C to 3.0 V. The discharge capacity at this time was the initial discharge capacity, denoted as D0. Subsequently, according to the above process, cyclic tests were carried out in the 3.0 - 4.3 V range, and the capacity values Dn (n = 1, 2, 3...) were recorded weekly. When the capacity Dn ≤ 80% * D0, the number of cycle weeks n was recorded as the cycle life.

[0300] Table 2

[0301]

[0302] In Table 2 above, when comparing the examples with Comparative Example 2, it can be seen that, compared with the ordinary PE film, the separator film of the present application has a higher air permeability. Thus, the cycle life of the examples is significantly higher than that of Comparative Example 2, indicating that the separator film meeting the conditions of the present application can improve the cycle performance of the battery. In addition, when comparing the examples with Comparative Examples 1 and 2, it can be seen that when the air permeability and ionic conductivity of the separator film are within the protection scope of the present application, the battery cycle life is higher.

[0303] The descriptions of the above embodiments tend to emphasize the differences between the embodiments. For their similarities, reference can be made to each other. For the sake of brevity, they will not be elaborated herein.

[0304] It should be noted that the present application is not limited to the above embodiments. The above embodiments are only examples. Embodiments with the same constitution and the same function and effect as the technical idea within the technical solution scope of the present application are included in the technical scope of the present application. In addition, within the scope not departing from the gist of the present application, various modifications that can be conceived by those skilled in the art to the embodiments and other modes constructed by combining some constituent elements of the embodiments are also included in the scope of the present application.

Claims

1. An isolation film, characterized in that, It includes a base film and a filler disposed in the porous structure of the base film. The filler includes a polymer matrix, an electrolyte salt, and a plasticizer. The polymer matrix includes a copolymer of a first monomer unit and a second monomer unit; The first monomer unit includes at least one of an ethylenically unsaturated carbonate monomer unit, an ethylenically unsaturated sulfate monomer unit, an ethylenically unsaturated sulfonate monomer unit, an ethylenically unsaturated sulfone monomer unit, an ethylenically unsaturated carboxylate monomer, an ethylenically unsaturated phosphate monomer unit, an ethylenically unsaturated nitrile monomer unit, and an ethylenically unsaturated ether monomer unit. The second monomer unit includes an acrylate monomer unit.

2. The separator film according to claim 1, characterized in that, The number of acrylate groups contained in the acrylate monomer unit ≥ 2.

3. The separator film according to claim 1 or 2, wherein Based on the total mass of the polymer matrix, the mass percentage of the first monomer unit in the polymer matrix is 16% - 67%.

4. The separator film according to any one of claims 1 to 3, characterized in that, Based on the total mass of the polymer matrix, the mass percentage of the first monomer unit in the polymer matrix is 16% - 35%.

5. The separator film according to any one of claims 1-4, characterized in that, The polymer matrix further includes a homopolymer or copolymer of the first monomer unit.

6. The separator film according to any one of claims 1-5, characterized in that, The acrylate monomer unit includes one or more of ethylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, 1,4 - butanediol diacrylate, 1,4 - butanediol dimethacrylate, 1,3 - butanediol diacrylate, 1,3 - butanediol dimethacrylate, 1,6 - hexanediol diacrylate, 1,6 - hexanediol dimethacrylate, dipropylene glycol diacrylate, dipropylene glycol dimethacrylate, tripropylene glycol diacrylate, tripropylene glycol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, 2(propoxylated)neopentyl glycol diacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, polycyclohexyl acrylate, methoxypolyethylene glycol acrylate, ethoxylated trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, methoxypolyethylene glycol methacrylate, pentaerythritol triacrylate, propoxylated glycerol triacrylate, tris(2 - hydroxyethyl)isocyanurate triacrylate, bis(trimethylolpropane)tetraacrylate, pentaerythritol tetraacrylate, 4(ethoxy)pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate.

7. The separator film according to any one of claims 1-6, characterized in that, The ethylenically unsaturated carbonate monomer unit includes one or more of vinylene carbonate, ethylene vinyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, fluoroethylene carbonate, and chloroethylene carbonate; and / or, the ethylenically unsaturated sulfate monomer unit includes one or more of ethylene vinyl sulfite, vinyl sulfite, 4 - methyl vinyl sulfate, and 4 - ethyl vinyl sulfate; And / or, the ethylenically unsaturated sulfonate monomer units include one or more of 1,3-propylene sulfonic acid lactone, allyl p-toluenesulfonate, and 2,2-difluorovinyl 4-methylbenzenesulfonate; And / or, the ethylenically unsaturated sulfone monomer units include one or more of methyl vinyl sulfone, ethyl vinyl sulfone, cyclobutene sulfone, sulfolane, and cyclohexene sulfoxide; And / or, the ethylenically unsaturated carboxylate monomers include vinyl acetate; And / or, the ethylenically unsaturated phosphate monomer units include one or more of dimethyl vinyl phosphate, diethyl vinyl phosphate, diethyl allyl phosphate, diethyl butenyl phosphate, diethyl 1-buten-2-yl phosphonate, diethyl ethynyl phosphate, vinyl trifluoromethyl phosphate, vinyl-1-trifluoroethyl phosphate, diethyl fluorovinyl phosphate, and 1-trifluoropropenyl ethyl phosphate; And / or, the ethylenically unsaturated nitrile monomer units include one or more of acrylonitrile, succinonitrile, glutaronitrile, and adiponitrile; And / or, the ethylenically unsaturated ether monomer units include one or more of 1,3-dioxolane, ethylene oxide, 1,2-epoxypropane, 4-methyl-1,3-dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, ethylene glycol dimethyl ether, ethylene glycol diglycidyl ether, and triethylene glycol divinyl ether.

8. The separator film according to any one of claims 1-7, characterized in that, The electrolyte salt includes at least one of a lithium salt and a sodium salt.

9. The separator film according to claim 8, characterized in that, The lithium salt includes one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorooxalate borate, lithium bis(oxalate)borate, lithium difluorophosphate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate; And / or, the sodium salt includes one or several of NaPF6, NaClO4, NaBCl4, NaSO3CF3, and Na(CH3)C6H4SO3.

10. The separator film according to any one of claims 1-9, characterized in that, The plasticizer includes at least one of a chain ester organic solvent, a cyclic ester organic solvent, an ether organic solvent, or a sulfone organic solvent.

11. The separator film according to claim 10, characterized in that, The mass ratio of the polymer matrix in the filler is 10% - 50%; And / or, the mass ratio of the electrolyte salt in the filler is 10% - 20%; And / or, the mass ratio of the plasticizer in the filler is 40% - 70%.

12. The separator film according to any one of claims 1-11, characterized in that, The separator further includes the filler disposed on at least a part of the surface of the base film.

13. The separator film according to any one of claims 1-12, characterized in that, The separator further includes an inorganic coating disposed on at least one side surface of the base film, and the inorganic coating includes inorganic particles.

14. The separator film according to claim 13, wherein, The filler is disposed inside the inorganic layer coating and / or on at least a part of the surface of the inorganic coating.

15. The separator film according to any one of claims 1-14, characterized in that, The base film includes at least one of a polyolefin base film, a polyvinyl fluoride base film, a cellulose-containing nanofiber base film, or a polyimide base film.

16. The separator film according to any one of claims 1 to 15, characterized in that, The air permeability AP of the separator satisfies: AP≥20000 s / 100 mL, and the ionic conductivity λ of the separator satisfies: λ≥0.1 mS / cm.

17. The separator film according to any one of claims 1-16, characterized in that, The air permeability of the separator membrane satisfies: 31000 s / 100 mL ≤ AP ≤ 50100 s / 100 mL.

18. The separator film according to any one of claims 1-17, characterized in that, The ionic conductivity λ of the separator membrane satisfies: 0.2 mS / cm ≤ λ < 0.6 mS / cm.

19. A battery, characterized in that, It includes a positive electrode sheet, a negative electrode sheet, and the separator membrane according to any one of claims 1-18, and the separator membrane is disposed between the positive electrode sheet and the negative electrode sheet.

20. The battery according to claim 19, wherein, The battery further includes a first electrolyte disposed between the positive electrode sheet and the separator membrane, and a second electrolyte disposed between the negative electrode sheet and the separator membrane.

21. The battery according to claim 20, characterized in that, The composition of the first electrolyte is different from that of the second electrolyte; and / or, the content of the first electrolyte is different from that of the second electrolyte.

22. An electrical device, characterized in that, It includes the battery according to any one of claims 19-21.

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