Composite flame-retardant separator, and preparation method therefor and use thereof

Abstract

A composite flame-retardant separator, and a preparation method therefor and the use thereof. The composite flame-retardant separator comprises: a base membrane (10), an interface layer (30), and a flame-retardant layer (20), wherein the interface layer (30) is located between the base membrane (10) and the flame-retardant layer (20); the material of the base membrane (10) comprises a fluorine-containing organic substance and a toughening agent; the material of the flame-retardant layer (20) comprises aramid fibers; the material of the interface layer (30) comprises a fluorine-containing organic substance, a toughening agent and aramid fibers; and the interface layer (30) is of a network-like structure. The composite flame-retardant separator has a relatively high strength and electrical conductivity.

Description

Composite flame-retardant separator and preparation method and application thereof

[0001] The present application claims priority to the Chinese patent application No. 202410448925.6, filed on April 15, 2024, and entitled "Composite flame-retardant separator and preparation method and application thereof", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of batteries, in particular to a composite flame-retardant separator, a preparation method of the composite flame-retardant separator and a lithium ion battery. BACKGROUND

[0003] A lithium battery includes four materials, namely, a positive electrode, a negative electrode, a separator and an electrolyte. In the structure of the lithium battery, the separator is one of the key inner components. The separator is mainly a polyolefin separator mainly made of polyethylene and polypropylene. The performance of the separator determines the interface structure and internal resistance of the battery, and directly affects the capacity, cycle and safety performance of the battery. A separator with excellent performance plays an important role in improving the overall performance of the battery.

[0004] The current flame-retardant technology mainly relies on a flame retardant to achieve a flame-retardant effect. A flame-retardant layer is coated on the surface of a base film, and the flame-retardant layer is mainly composed of a flame retardant and a binder. However, the flame-retardant effect is not good, and the addition of a large amount of the flame retardant reduces the conductivity of the separator, hinders the transmission of lithium ions and affects the overall performance of the battery. TECHNICAL SOLUTION

[0005] Therefore, the present application provides a composite flame-retardant separator to improve the poor flame-retardant effect and poor conductivity of the existing flame-retardant separator.

[0006] In the embodiments of the present application, a composite flame-retardant separator includes a base film, an interface layer and a flame-retardant layer. The interface layer is located between the base film and the flame-retardant layer. The material of the base film includes a fluorine-containing organic substance and a toughening agent. The material of the flame-retardant layer includes aramid fiber. The material of the interface layer includes the fluorine-containing organic substance, the toughening agent and the aramid fiber.

[0007] Optionally, in some embodiments, the interface layer has a reticular structure.

[0008] Optionally, in some embodiments, the fluorine-containing organic substance includes one or more of polyvinylidene fluoride, polyvinylidene fluoride-hydrofluoric acid copolymer and polyvinylidene fluoride-trifluoroethylene copolymer.

[0009] Optionally, in some embodiments, the toughening agent includes one or more of silicon carbide whisker, silicon nitride whisker, glass fiber and polymethyl methacrylate.

[0010] Optionally, in some embodiments, the aramid includes one or more of meta-aramid and para-aramid.

[0011] Optionally, in some embodiments, the mass ratio of the fluorine-containing organic matter and the toughening agent in the base film is (0.6-0.9):(0.01-0.5).

[0012] Optionally, in some embodiments, the flame-retardant layer further includes a solid-state electrolyte, the solid-state electrolyte including one or more of LATP, doped or undoped LLZO.

[0013] Optionally, in some embodiments, the doped LLZO has a general formula of Li 7-x La3Zr 2-x M x O 12 , wherein 0.25≤x<2, and the doping element M includes one or more of Ta, Ga, Al, and Nb.

[0014] Optionally, in some embodiments, the doped LLZO includes Li 6.7 La3Zr 1.7 Ta 0.3 O 12 , Li 6.5 La3Zr 1.5 Ga 0.5 O 12 , Li 6.2 La3Zr 1.2 Al 0.8 O 12 , Li6La3ZrNbO 12 , Li 5.8 La3Zr 0.8 Ta 1.2 O 12 , Li 5.5 La3Zr 0.5 Nb 1.5 O 12 , Li 5.4 La3Zr 0.4 Ga 1.6 O 12 , Li 5.2 La3Zr 0.2 Ta 1.8 O 12 , Li 5.1 La3Zr 0.1 Nb 1.9 O 12 , Li 6.75 La3Zr 1.75 Nb 0.25 O12、 Li 5.8 La3Zr 1.4 Ta 0.6 Al 0.2 O 12 One or more of .

[0015] Optionally, in some embodiments, in the flame retardant layer, the mass ratio of the solid electrolyte to the aramid is (1-10):1.

[0016] Optionally, in some embodiments, the composite flame-retardant membrane has a thickness of 8 to 24 μm.

[0017] Optionally, in some embodiments, the base film has a thickness of 7 to 19 μm.

[0018] Optionally, in some embodiments, the thickness of the interface layer is 100-200 nm.

[0019] Optionally, in some embodiments, the thickness of the flame retardant layer is 1 to 4 μm.

[0020] Accordingly, an embodiment of the present application further provides a method for preparing a composite flame-retardant diaphragm, which comprises:

[0021] Providing a prefabricated base film, wherein the material of the prefabricated base film includes a fluorine-containing organic compound and a toughening agent;

[0022] providing a second mixed liquid, wherein the second mixed liquid includes aramid; and

[0023] The second mixed liquid is set on the prefabricated base membrane, wherein part of the second mixed liquid penetrates into the upper surface of the prefabricated base membrane to form a base membrane and an interface layer bonded to the base membrane; the second mixed liquid that has not penetrated into the prefabricated base membrane forms a flame retardant layer on the interface layer to obtain a composite flame retardant diaphragm.

[0024] Optionally, in some embodiments, the method for preparing the prefabricated base film includes:

[0025] Providing a first mixed liquid, wherein the first mixed liquid includes a fluorine-containing organic compound, a toughening agent, and a first solvent;

[0026] A substrate is provided, and the first mixed liquid is disposed on the substrate to obtain a prefabricated base film.

[0027] Optionally, in some embodiments, the second mixed liquid further includes a solid electrolyte, a dispersant and a second solvent.

[0028] Optionally, in some embodiments, the first solvent and the second solvent each independently comprises one or more of N-methylpyrrolidone, dimethylacetamide, N,N-dimethylformamide, dimethylsulfoxide, acetone, dichloroethane, chloroform, ethanol, isopropanol, toluene.

[0029] Optionally, in some embodiments, the dispersant comprises one or more of polyacrylamide, polyvinylpyrrolidone, carboxymethyl cellulose, and acrylic resin.

[0030] Optionally, in some embodiments, the fluorine-containing organic compound comprises one or more of polyvinylidene fluoride, polyvinylidene fluoride-hydrofluoric acid copolymer, polyvinylidene fluoride-trifluoroethylene copolymer.

[0031] Optionally, in some embodiments, the toughening agent comprises one or more of silicon carbide whisker, silicon nitride whisker, glass fiber, polymethyl methacrylate.

[0032] Optionally, in some embodiments, the solid-state electrolyte comprises one or more of LATP, doped or undoped LLZO, wherein the doping element in the doped LLZO comprises one or more of tantalum, gallium, aluminum, niobium.

[0033] Optionally, in some embodiments, the aramid fiber comprises one or more of meta-aramid fiber and para-aramid fiber.

[0034] Optionally, in some embodiments, the mass ratio of the fluorine-containing organic compound and the toughening agent is (0.6-0.9):(0.01-0.5).

[0035] Optionally, in some embodiments, in the first mixed solution, the mass concentration of the fluorine-containing organic compound is 89.9-134.8 mg / mL.

[0036] Optionally, in some embodiments, the mass ratio of the solid-state electrolyte and the aramid fiber is (1-10):1.

[0037] Optionally, in some embodiments, the mass ratio of the dispersant and the second solvent is 1:(200-1000).

[0038] Optionally, in some embodiments, in the second mixed solution, the mass concentration of the solid-state electrolyte is 17.236-237 mg / mL.

[0039] Optionally, in some embodiments, the method of disposing the first mixed solution on a substrate comprises first coating.

[0040] Optionally, in some embodiments, after disposing the first mixed solution on the substrate, further comprising first phase inversion, drying, to obtain a pre-prepared base film.

[0041] Optionally, in some embodiments, the method of providing the second mixture comprises dispersing the solid electrolyte and the dispersant in the second solvent, and then adding the aramid fiber and continuing stirring.

[0042] Optionally, in some embodiments, the method of disposing the second mixture on the pre-made base film comprises a second coating.

[0043] Optionally, in some embodiments, the method of disposing the second mixture on the pre-made base film further comprises a second phase inversion and drying after the disposing.

[0044] Optionally, in some embodiments, the temperature of the baking and the drying is independently 40-80°C.

[0045] Optionally, in some embodiments, the time of the baking and the drying is independently 1-300 min.

[0046] Optionally, in some embodiments, the dispersing comprises dispersing at a speed of n1 for t1.

[0047] Optionally, in some embodiments, the stirring comprises stirring at a speed of n2 for t2.

[0048] Optionally, in some embodiments, the first coating and the second coating independently comprise one or more of spin coating, spray coating, wire bar coating, and dip coating.

[0049] Optionally, in some embodiments, the n1 and the n2 are independently 500-3000 r / min.

[0050] Optionally, in some embodiments, the t1 and the t2 are independently 1-6 h.

[0051] Correspondingly, the present application also provides a battery comprising the composite flame-retardant separator, wherein the composite flame-retardant separator comprises a base film, an interface layer, and a flame-retardant layer, the interface layer is between the base film and the flame-retardant layer, the material of the base film comprises fluorine-containing organic matter and a toughening agent, the material of the flame-retardant layer comprises aramid fiber, and the material of the interface layer comprises the fluorine-containing organic matter, the toughening agent, and the aramid fiber.

[0052] Optionally, in some embodiments, the interface layer has a reticular structure.

[0053] Optionally, in some embodiments, the fluorine-containing organic matter comprises one or more of polyvinylidene fluoride, polyvinylidene fluoride-hydrofluoric acid copolymer, and polyvinylidene fluoride-trifluoroethylene copolymer.

[0054] Optionally, in some embodiments, the toughening agent includes one or more of silicon carbide whiskers, silicon nitride whiskers, glass fibers, polymethyl methacrylate.

[0055] Optionally, in some embodiments, the aramid includes one or more of meta-aramid and para-aramid.

[0056] Optionally, in some embodiments, the mass ratio of the fluorine-containing organic matter and the toughening agent in the base film is (0.6-0.9):(0.01-0.5).

[0057] Optionally, in some embodiments, the thickness of the composite flame-retardant separator is 8-24 μm.

[0058] Optionally, in some embodiments, the thickness of the base film is 7-19 μm.

[0059] Optionally, in some embodiments, the thickness of the interface layer is 100-200 nm.

[0060] Optionally, in some embodiments, the thickness of the flame-retardant layer is 1-4 μm.

[0061] Optionally, in some embodiments, the flame-retardant layer further includes a solid electrolyte, and the solid electrolyte includes one or more of LATP, doped or undoped LLZO.

[0062] Optionally, in some embodiments, the doped LLZO has a general formula of Li 7-x La3Zr 2-x M x O 12 , wherein 0.25≤x<2, and the doping element M includes one or more of Ta, Ga, Al, Nb.

[0063] Optionally, in some embodiments, the doped LLZO includes Li 6.7 La3Zr 1.7 Ta 0.3 O 12 , Li 6.5 La3Zr 1.5 Ga 0.5 O 12 , Li 6.2 La3Zr 1.2 Al 0.8 O 12 , Li6La3ZrNbO 12 , Li 5.8 La3Zr 0.8 Ta 1.2 O 12 , Li 5.5 La3Zr0.5 Nb 1.5 O 12 , Li 5.4 La3Zr 0.4 Ga 1.6 O 12 , Li 5.2 La3Zr 0.2 Ta 1.8 O 12 , Li 5.1 La3Zr 0.1 Nb 1.9 O 12 , Li 6.75 La3Zr 1.75 Nb 0.25 O 12、 Li 5.8 La3Zr 1.4 Ta 0.6 Al 0.2 O 12 one or more of.

[0064] Optionally, in some embodiments, in the flame-retardant layer, the mass ratio of the solid-state electrolyte to the aramid fiber is (1-10):1.

[0065] In the technical solutions of the present application:

[0066] The Chinese name of PVDF is polyvinylidene fluoride; the Chinese name of PVDF-HFP is polyvinylidene fluoride-hydrofluoric acid copolymer; the Chinese name of PVDF-TrFE is polyvinylidene fluoride-trifluoroethylene copolymer; the Chinese name of PMMA is polymethyl methacrylate; the Chinese name of NMP is N-methyl pyrrolidone; the Chinese name of DMAc is dimethylacetamide; the Chinese name of DMF is N,N-dimethylformamide; the Chinese name of DMSO is dimethyl sulfoxide; LATP represents lithium aluminum titanium phosphate; LLZO represents lithium lanthanum zirconium oxide. Beneficial effects

[0067] In the composite flame-retardant separator provided by the present application, the base film uses fluorine-containing organic matter as the main film-forming material, which has good flame-retardant effect. The toughening agent is added to the fluorine-containing organic matter, which is equivalent to forming a skeleton in the base film, thereby improving the strength of the base film and increasing the running speed, thus further improving the production efficiency. The aramid fiber further improves the mechanical properties of the composite flame-retardant separator. The aramid fiber carbonizes and thickens rapidly when it encounters high temperature, forming a thermal barrier to isolate high temperature and further improve the flame-retardant properties. The fluorine-containing organic matter has stronger polarity and higher dielectric constant, which improves the wettability of the composite flame-retardant separator and helps the ionization of lithium salt, thereby improving the conductivity efficiency. The network structure formed between the base film and the flame-retardant layer makes the base film and the flame-retardant layer firmly connected. BRIEF DESCRIPTION OF DRAWINGS

[0068] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0069] Fig. 1 is an SEM image of the composite flame-retardant separator prepared in Embodiment 1 of the present application;

[0070] Fig. 2 is a flow chart of a preparation method of a composite flame-retardant separator provided in the present application;

[0071] Fig. 3 is another SEM image of the composite flame-retardant separator prepared in Embodiment 1 of the present application.

[0072] Embodiments of the present application

[0073] The technical solutions in the embodiments of the present application will be described clearly and completely in the following description of the embodiments of the present application in conjunction with the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort fall within the scope of the present application. In addition, it should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not intended to limit the present application.

[0074] In the present application, the orientation words such as "upper" and "lower" generally refer to the upper and lower in the actual use or working state of the device, and specifically refer to the direction of the drawing surface in the drawings. In addition, in the description of the present application, the term "comprising" means "including but not limited to". The terms first, second, third, etc. are only used as labels, and do not impose numerical requirements or establish an order.

[0075] In the present application, the association relationship of the associated objects is described by "and / or", which means that there can be three kinds of relationships, for example, A and / or B, which means that A exists alone, A and B exist together, and B exists alone. Wherein A and B can be singular or plural.

[0076] In the present application, "at least one" means one or more, and "multiple" means two or more. "One or more", "at least one of the following (one)", or similar expressions, refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can mean a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

[0077] Various embodiments of the present application can exist in the form of a range; it should be understood that the description in the form of a range is only for the convenience and brevity, and should not be understood as a hard limit on the scope of the present application; therefore, it should be considered that the described range has been specifically disclosed all possible sub-ranges and single values within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. In addition, whenever a numerical range is indicated in this document, it refers to any cited number (fraction or integer) within the indicated range.

[0078] The technical solutions of the present application are as follows:

[0079] In a first aspect, the embodiments of the present application provide a composite flame-retardant separator, comprising a base film 10, an interface layer 30, and a flame-retardant layer 20, wherein the interface layer 30 is located between the base film 10 and the flame-retardant layer 20. The material of the base film 10 includes fluorine-containing organic matter and a toughening agent, the material of the flame-retardant layer 20 includes aramid fiber, and the material of the interface layer 30 includes the fluorine-containing organic matter, the toughening agent, and the aramid fiber. The interface layer 30 is a network structure.

[0080] In the embodiments of the present application, the base film 10 uses fluorine-containing organic matter as the main film-forming material, which has good flame-retardant effect. The toughening agent is added to the fluorine-containing organic matter, which is equivalent to forming a skeleton in the base film 10, thereby improving the strength of the base film 10 and increasing the running speed, thus further improving the production efficiency. The addition of aramid fiber further improves the mechanical properties of the composite flame-retardant separator. When the aramid fiber is subjected to high temperature, it will rapidly carbonize and thicken to form an insulating barrier, thereby isolating the high temperature and further improving the flame-retardant properties. The fluorine-containing organic matter has stronger polarity and higher dielectric constant, which improves the wettability of the composite flame-retardant separator and helps the ionization of lithium salt, thereby improving the conductivity efficiency. The network structure formed by the fluorine-containing organic matter, the toughening agent, and the aramid fiber makes the base film 10 and the flame-retardant layer 20 firmly connected.

[0081] In some embodiments, the mass ratio of the fluorine-containing organic matter and the toughening agent in the base film 10 is (0.6-0.9):(0.01-0.5), for example, it can be 0.6:0.01, 0.6:0.02, 0.6:0.05, 0.6:0.08, 0.6:0.1, 0.6:0.12, 0.6:0.14, 0.6:0.16, 0.6:0.18, 0.6:0.2, 0.6:0.22, 0.6:0.24, 0.6:0.26, 0.6:0.28, 0.6:0.3, 0.6:0.32, 0.6:0.35, 0.6:0.38, 0.6:0.4, 0.6:0.42, 0.6:0.46, 0.6:0.48, 0.6:0.5, 0.7:0.01, 0.7:0.05, 0.7:0.1, 0.7:0.15, 0.7:0.2, 0.7:0.25, 0.7:0.3, 0.7:0.35, 0.7:0.4, 0.7:0.45, 0.7:0.5, 0.8:0.01, 0.8:0.05, 0.8:0.1, 0.8:0.15, 0.8:0.2, 0.8:0.25, 0.8:0.3, 0.8:0.35, 0.8:0.4, 0.8:0.45, 0.8:0.5, 0.9:0.01, 0.9:0.05, 0.9:0.1, 0.9:0.15, 0.9:0.2, 0.9:0.25, 0.9:0.3, 0.9:0.35, 0.9:0.4, 0.9:0.45, 0.9:0.5, etc. Within the mass ratio range, it is beneficial to form the base film 10 with excellent flame retardation performance and strength.

[0082] In some embodiments, the fluorine-containing organic matter includes one or more of polyvinylidene fluoride, polyvinylidene fluoride-hydrofluoric acid copolymer, and polyvinylidene fluoride-trifluoroethylene copolymer.

[0083] In some embodiments, the toughening agent includes one or more of silicon carbide whisker, silicon nitride whisker, glass fiber, and PMMA (polymethyl methacrylate).

[0084] In some embodiments, the aramid fiber includes one or more of meta-aramid fiber and para-aramid fiber.

[0085] In some embodiments, the flame-retardant layer 20 further includes a solid-state electrolyte.

[0086] Further, the solid-state electrolyte includes one or more of LATP, doped or undoped LLZO.

[0087] Still further, the doped LLZO has a general formula of Li 7-x La3Zr 2-x M xO 12 wherein 0.25≤x<2, the doping element M includes one or more of tantalum (Ta), gallium (Ga), aluminum (Al), and niobium (Nb).

[0088] For example, the doped LLZO includes Li 6.7 La3Zr 1.7 Ta 0.3 O 12 , Li 6.5 La3Zr 1.5 Ga 0.5 O 12 , Li 6.2 La3Zr 1.2 Al 0.8 O 12 , Li6La3ZrNbO 12 , Li 5.8 La3Zr 0.8 Ta 1.2 O 12 , Li 5.5 La3Zr 0.5 Nb 1.5 O 12 , Li 5.4 La3Zr 0.4 Ga 1.6 O 12 , Li 5.2 La3Zr 0.2 Ta 1.8 O 12 , Li 5.1 La3Zr 0.1 Nb 1.9 O 12 , Li 6.75 La3Zr 1.75 Nb 0.25 O 12、 Li 5.8 La3Zr 1.4 Ta 0.6 Al 0.2 O 12 one or more of the above.

[0089] In some embodiments, the mass ratio of the solid-state electrolyte to the aramid fiber in the flame-retardant layer 20 is (1-10): 1, for example, it can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc. Within the mass ratio range, it is beneficial to improve the high temperature resistance, mechanical strength and electrical conductivity of the composite flame-retardant separator.

[0090] In some embodiments, the thickness of the composite flame-retardant separator is 8-24 μm, for example, it can be 8 μm, 8.1 μm, 8.5 μm, 9 μm, 10 μm, 11 μm, 12 μm, 14 μm, 15 μm, 16 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 23.2 μm, 23.5 μm, 24 μm, etc. Within the thickness range, the mechanical strength of the composite flame-retardant separator is improved, and the conductive performance is excellent.

[0091] In some embodiments, the thickness of the base film 10 is 7-19 μm, for example, it can be 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, etc.

[0092] In some embodiments, the thickness of the interface layer 30 is 100-200 nm, for example, it can be 100 nm, 105 nm, 110 nm, 115 nm, 120 nm, 125 nm, 130 nm, 135 nm, 140 nm, 145 nm, 150 nm, 155 nm, 160 nm, 165 nm, 170 nm, 175 nm, 180 nm, 185 nm, 190 nm, 195 nm, 200 nm, etc.

[0093] In some embodiments, the thickness of the flame-retardant layer 20 is 1-4 μm, for example, it can be 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, 2 μm, 2.2 μm, 2.5 μm, 2.8 μm, 3 μm, 3.2 μm, 3.4 μm, 3.5 μm, 3.6 μm, 3.8 μm, 4 μm, etc.

[0094] In a second aspect, referring to FIG. 2, the application also provides a preparation method of the composite flame-retardant separator, comprising:

[0095] S01, providing a pre-prepared base film 10, the material of the pre-prepared base film 10 comprising fluorine-containing organic matter and a toughening agent;

[0096] S02, providing a second mixed solution, the second mixed solution comprising aramid fiber; and

[0097] S03, disposing the second mixed solution on the pre-prepared base film 10, wherein part of the second mixed solution penetrates into the upper surface of the pre-prepared base film 10, forming a base film 10 and an interface layer 30 combined with the base film 10; the second mixed solution that does not penetrate into the pre-prepared base film 10 forms a flame-retardant layer 20 on the interface layer 30, obtaining a composite flame-retardant separator.

[0098] In the S01,

[0099] The method for preparing the preformed base film 10 includes:

[0100] S011, providing a first mixed solution including a fluorine-containing organic matter, a toughening agent, and a first solvent;

[0101] S012, providing a substrate, and disposing the first mixed solution on the substrate to obtain the preformed base film 10.

[0102] In some embodiments, the first solvent includes one or more of N-methyl pyrrolidone, dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, acetone, dichloroethane, chloroform, ethanol, isopropanol, toluene.

[0103] In some embodiments, the fluorine-containing organic matter includes one or more of polyvinylidene fluoride, polyvinylidene fluoride-hydrofluoric acid copolymer, polyvinylidene fluoride-trifluoroethylene copolymer.

[0104] In some embodiments, the toughening agent includes one or more of silicon carbide whisker, silicon nitride whisker, glass fiber, PMMA.

[0105] In some embodiments, the mass ratio of the fluorine-containing organic matter and the toughening agent is (0.6-0.9):(0.01-0.5), for example, it can be 0.6:0.01, 0.6:0.02, 0.6:0.05, 0.6:0.08, 0.6:0.1, 0.6:0.12, 0.6:0.14, 0.6:0.16, 0.6:0.18, 0.6:0.2, 0.6:0.22, 0.6:0.24, 0.6:0.26, 0.6:0.28, 0.6:0.3, 0.6:0.32, 0.6:0.35, 0.6:0.38, 0.6:0.4, 0.6:0.42, 0.6:0.46, 0.6:0.48, 0.6:0.5, 0.7:0.01, 0.7:0.05, 0.7:0.1, 0.7:0.15, 0.7:0.2, 0.7:0.25, 0.7:0.3, 0.7:0.35, 0.7:0.4, 0.7:0.45, 0.7:0.5, 0.8:0.01, 0.8:0.05, 0.8:0.1, 0.8:0.15, 0.8:0.2, 0.8:0.25, 0.8:0.3, 0.8:0.35, 0.8:0.4, 0.8:0.45, 0.8:0.5, 0.9:0.01, 0.9:0.05, 0.9:0.1, 0.9:0.15, 0.9:0.2, 0.9:0.25, 0.9:0.3, 0.9:0.35, 0.9:0.4, 0.9:0.45, 0.9:0.5, etc. Within the mass ratio range, it is beneficial to form a base film 10 with excellent flame retardation performance and strength.

[0106] Further, the mass concentration of the fluorine-containing organic matter in the first mixed solution is 89.9-134.8 mg / mL, for example, can be 89.8 mg / mL, 90 mg / mL, 92 mg / mL, 95 mg / mL, 98 mg / mL, 100 mg / mL, 102 mg / mL, 105 mg / mL, 108 mg / mL, 110 mg / mL, 112 mg / mL, 115 mg / mL, 118 mg / mL, 120 mg / mL, 122 mg / mL, 124 mg / mL, 126 mg / mL, 128 mg / mL, 130 mg / mL, 132 mg / mL, 134 mg / mL, 134.8 mg / mL, etc. Within the range of the mass concentration, it is beneficial to fully dissolve the fluorine-containing organic matter.

[0107] In the S012, the first mixed solution is disposed on the substrate.

[0108] In some embodiments, the method of disposing the first mixed solution on the substrate includes a first coating.

[0109] Further, the first coating method includes one or more of spin coating, spray coating, wire bar coating, dip coating.

[0110] In some embodiments, after the first mixed solution is disposed on the substrate, it further includes a first phase inversion, and drying to obtain a base film 10.

[0111] In some embodiments, the substrate includes a release film or a glass substrate.

[0112] In some embodiments, after the first mixed solution is disposed on the substrate, it further includes a first phase inversion, and drying to obtain a base film 10.

[0113] Further, the drying temperature is 40-80°C, for example, can be 40°C, 50°C, 60°C, 70°C, 80°C, etc., and the time is 1-300 min, for example, can be 1 min, 10 min, 50 min, 60 min, 80 min, 100 min, 120 min, 150 min, 180 min, 200 min, 220 min, 250 min, 280 min, 300 min, etc. Within the range of the temperature and time, it is beneficial to dry the first mixed solution after the first phase inversion and obtain the base film 10.

[0114] It can be understood that the first phase inversion is a conventional technique in the art, and the purpose is to remove the solvent to quickly form a film and create pores.

[0115] It can be understood that after the first phase inversion, the film is detached from the substrate, and then dried to obtain the base film 10.

[0116] The S02 includes:

[0117] In some embodiments, the second mixture further includes a solid-state electrolyte, a dispersant, and a second solvent.

[0118] In some embodiments, the solid-state electrolyte includes one or more of LATP, doped or undoped LLZO.

[0119] Further, the doped LLZO has a general formula of Li 7-x La3Zr 2-x M x O 12 wherein 0.25≤x<2, and the doping element M includes one or more of tantalum (Ta), gallium (Ga), aluminum (Al), and niobium (Nb).

[0120] Further, the doped LLZO includes Li 6.7 La3Zr 1.7 Ta 0.3 O 12 , Li 6.5 La3Zr 1.5 Ga 0.5 O 12 , Li 6.2 La3Zr 1.2 Al 0.8 O 12 , Li6La3ZrNbO 12 , Li 5.8 La3Zr 0.8 Ta 1.2 O 12 , Li 5.5 La3Zr 0.5 Nb 1.5 O 12 , Li 5.4 La3Zr 0.4 Ga 1.6 O 12 , Li 5.2 La3Zr 0.2 Ta 1.8 O 12 , Li 5.1 La3Zr 0.1 Nb 1.9 O 12 , Li 6.75 La3Zr 1.75 Nb 0.25 O 12、 Li 5.8 La3Zr 1.4 Ta 0.6 Al 0.2 O 12 , and the like.

[0121] The dispersant includes one or more of polyacrylamide, polyvinylpyrrolidone, carboxymethyl cellulose, and acrylic resin.

[0122] In some embodiments, the second solvent includes one or more of N-methylpyrrolidone, dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, acetone, dichloroethane, chloroform, ethanol, isopropanol, toluene.

[0123] In some embodiments, the aramid fiber includes one or more of meta-aramid fiber and para-aramid fiber.

[0124] In some embodiments, the mass ratio of the solid-state electrolyte to the aramid fiber is (1-10):1, which can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc. Within the mass ratio range, the high-temperature resistance, mechanical strength, and electrical conductivity of the composite flame-retardant separator are improved.

[0125] In some embodiments, the mass ratio of the dispersant to the second solvent is 1:(200-1000), which can be 1:200, 1:250, 1:300, 1:350, 1:400, 1:450, 1:500, 1:550, 1:600, 1:650, 1:700, 1:750, 1:800, 1:850, 1:900, 1:950, 1:1000, etc.

[0126] Further, in the second mixed solution, the mass concentration of the solid-state electrolyte is 17.236-237 mg / mL, which can be 17.236 mg / mL, 18 mg / mL, 20 mg / mL, 50 mg / mL, 80 mg / mL, 100 mg / mL, 110 mg / mL, 130 mg / mL, 150 mg / mL, 180 mg / mL, 200 mg / mL, 210 mg / mL, 220 mg / mL, 230 mg / mL, 235 mg / mL, 237 mg / mL, etc. Within the mass concentration range, the solid-state electrolyte is fully dissolved.

[0127] Further, the method for providing the second mixed solution includes dispersing the solid-state electrolyte and the dispersant in the second solvent, and then adding the aramid fiber and continuing to stir.

[0128] In some embodiments, the dispersing includes dispersing at n1 revolutions per minute for t1 hours.

[0129] In some embodiments, the stirring includes stirring at n2 revolutions per minute for t2 hours.

[0130] Further, n1 is 500-3000 r / min, for example, it can be 500 r / min, 550 r / min, 580 r / min, 1000 r / min, 1100 r / min, 1200 r / min, 1500 r / min, 1800 r / min, 2000 r / min, 2200 r / min, 2500 r / min, 2600 r / min, 2800 r / min, 3000 r / min, etc.

[0131] Further, t1 is 1-6 h, for example, it can be 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, etc. Within the speed and time range of the dispersion, it is beneficial to dissolve and fully disperse the solid electrolyte.

[0132] Further, n2 is 500-3000 r / min, for example, it can be 500 r / min, 550 r / min, 580 r / min, 1000 r / min, 1100 r / min, 1200 r / min, 1500 r / min, 1800 r / min, 2000 r / min, 2200 r / min, 2500 r / min, 2600 r / min, 2800 r / min, 3000 r / min, etc.

[0133] Further, t2 is 1-6 h, for example, it can be 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, etc. Within the speed and time range of the stirring, it is beneficial to uniformly stir and mix the aramid fiber.

[0134] In S03, the second mixture liquid is disposed on the base film 10.

[0135] In some embodiments, the method of disposing the second mixture liquid on the base film 10 includes a second coating.

[0136] Further, the second coating method includes one or more of spin coating, spray coating, wire bar coating, dip coating, etc.

[0137] In some embodiments, after the second mixture liquid is disposed on the base film 10, it further includes a second phase inversion and drying.

[0138] It can be understood that the second phase inversion is a conventional technique in the art, and the purpose is to remove the dispersant and solvent, and to quickly form a film and create pores.

[0139] Further, the drying temperature is 40-80℃, for example, can be 40℃, 50℃, 60℃, 70℃, 80℃, etc., and the time is 1-300min, for example, can be 1min, 10min, 50min, 60min, 80min, 100min, 120min, 150min, 180min, 200min, 220min, 250min, 280min, 300min, etc. Within the temperature and time range, the second mixed solution after the second phase conversion is dried and a composite flame-retardant separator is obtained.

[0140] In the embodiment of the application, part of the second solvent in the second mixed solution has a dissolving effect on the fluorine-containing organic matter in the pre-prepared base film 10. After coating, this part of the solvent will dissolve a small amount of fluorine-containing organic matter. The dissolved fluorine-containing organic matter is a flexible polymer, and aramid is a zigzag-shaped macromolecule. By using the flexibility of the fluorine-containing organic matter and aramid, the two are mixed and staggered. At the same time, the toughening agent is a rod-shaped structure, which is inserted into the fluorine-containing organic matter and aramid and arranged in a random flexible manner. After drying and solvent evaporation, a network structure is formed, so that the interface layer 30 is formed between the base film 10 and the flame-retardant layer 20, and the combination is tight.

[0141] In a third aspect, the embodiment of the application also provides a battery, which comprises the composite flame-retardant separator of the first aspect or is prepared by the preparation method of the second aspect.

[0142] The application will be specifically described below through specific examples. The following examples are only part of the examples of the application and are not a limitation of the application.

[0143] Example 1

[0144] The embodiment provides a composite flame-retardant separator preparation method as follows:

[0145] 800g of PVDF and 250g of silicon carbide whiskers were added to 4500g of solvent DMF, mixed at 1500r / min for 3h to obtain a first mixed solution. Then, a coating machine was used to coat the first mixed solution on a release film. After phase conversion, drying, demolding and winding, a base film with a thickness of 12μm was obtained.

[0146] 250g of solid-state electrolyte LLZO and 12.5g of dispersant polyacrylamide were added to a mixed solvent of 2250g of DMF and 250g of ethanol, and dispersed at 1500r / min for 3h. Then, 25g of meta-aramid was added and stirred at 1500r / min for another 3h to obtain a second mixed solution. A coating machine was used to coat the second mixed solution on the base film. After drying and winding, a composite flame-retardant separator with a thickness of 14.15μm was obtained.

[0147] Example 2

[0148] The preparation method of the composite flame-retardant separator is as follows:

[0149] PVDF with a mass of 600 g and 10 g of silicon carbide whiskers were added to 2700 g of solvent DMF, mixed at 500 r / min for 6 h, to obtain a first mixed solution; then a coating machine was used to coat the first mixed solution on a release film, and the coated film was subjected to phase inversion, drying, demolding and winding.

[0150] 500 g of solid-state electrolyte LLZO and 25 g of dispersant polyacrylamide were added to 4500 g of mixed solvent of DMF and 500 g of ethanol, and dispersed at 500 r / min for 6 h, then 500 g of meta-aramid was added and stirred at 500 r / min for 6 h to obtain a second mixed solution, and a coating machine was used to coat the second mixed solution on a base film, and the coated film was dried and wound to obtain a composite flame-retardant separator.

[0151] Example 3

[0152] The preparation method of the composite flame-retardant separator is as follows:

[0153] PVDF with a mass of 900 g and 500 g of silicon carbide whiskers were added to 6000 g of solvent DMF, mixed at 3000 r / min for 3 h, to obtain a first mixed solution; then a coating machine was used to coat the first mixed solution on a release film, and the coated film was subjected to phase inversion, drying, demolding and winding.

[0154] 500 g of solid-state electrolyte LLZO and 25 g of dispersant polyacrylamide were added to 4500 g of mixed solvent of DMF and 500 g of ethanol, and dispersed at 3000 r / min for 1 h, then 50 g of meta-aramid was added and stirred at 3000 r / min for 1 h to obtain a second mixed solution, and a coating machine was used to coat the second mixed solution on a base film, and the coated film was dried and wound to obtain a composite flame-retardant separator.

[0155] Example 4

[0156] The example is basically the same as example 1, and the difference is that PVDF is replaced by PVDF-HFP.

[0157] Example 5

[0158] The example is basically the same as example 1, and the difference is that PVDF is replaced by PVDF-TrFE.

[0159] Example 6

[0160] The example is basically the same as example 1, and the difference is that meta-aramid is replaced by para-aramid.

[0161] Example 7

[0162] This example is basically the same as example 1, the difference is only that the LLZO is replaced by LATP.

[0163] Example 8

[0164] This example is basically the same as example 1, the difference is only that the LLZO is replaced by LLZO doped with niobium element, the molecular formula is Li 6.75 La3Zr 1.75 Nb 0.25 O 12 .

[0165] Example 9

[0166] This example is basically the same as example 1, the difference is only that the LLZO is replaced by LLZO doped with aluminum and tantalum elements, the molecular formula is Li 5.8 La3Zr 1.4 Ta 0.6 Al 0.2 O 12 .

[0167] Example 10

[0168] This example is basically the same as example 1, the difference is only that the silicon carbide whisker is replaced by silicon nitride whisker.

[0169] Example 11

[0170] This example is basically the same as example 1, the difference is only that the silicon carbide whisker is replaced by glass fiber.

[0171] Comparative Example 1

[0172] The difference between this comparative example and example 1 is that the amount of PVDF in example 1 is replaced by 10g, which cannot form a film.

[0173] Comparative Example 2

[0174] The difference between this comparative example and example 1 is that the meta-aramid in example 1 is removed.

[0175] Comparative Example 3

[0176] This comparative example is a commercially available conventional lithium battery separator.

[0177] Fig. 1 and Fig. 3 are SEM images of the composite flame-retardant separator prepared in example 1, from which it can be seen that an interface layer is formed between the base film and the flame-retardant layer, and particles are interspersed in the flame-retardant layer, improving the strength of the composite flame-retardant separator. The existence of the interface layer makes the base film and the flame-retardant layer combine quite tightly. In addition, the pore structure of the flame-retardant layer formed by aramid and solid electrolyte is rich, which enhances the affinity between the composite flame-retardant separator and the electrolyte, improves the liquid uptake, and effectively reduces the internal resistance of the battery.

[0178] The flame retardant performance, ion conductivity and tensile strength of the composite flame-retardant separator of Examples 1-11 and the battery separator of Comparative Example 2-3 were detected respectively, and the test results are shown in Table 1, wherein the flame retardant performance was determined by vertical combustion method; the ion conductivity was determined by alternating current impedance method; the tensile strength was tested in accordance with GB / T10403-2006 "Test Method for Tensile Properties of Plastic" and ASTM D882-10 "Standard Test Method for Tensile Properties of Thin Plastic Sheeting".

[0179] Table 1

[0180] From Table 1, it can be seen that:

[0181] Compared with Comparative Example 3, the combustion performance of the composite flame-retardant separator of the examples of the present application is very good, and in addition, the ion conductivity of the composite flame-retardant separator of the examples of the present application is higher than that of Comparative Example 3, which is because the base film uses fluorine-containing organic matter as the main film-forming material, which has good flame-retardant effect, and aramid will carbonize and thicken rapidly when it encounters high temperature, forming an insulating barrier to isolate high temperature, further improving the flame-retardant performance; the commercially available conventional lithium battery separator of Comparative Example 3 is a non-polar polymer, which has poor electrolyte wettability, resulting in large internal resistance and low ion conductivity of the battery, while the fluorine-containing organic matter of the present application has stronger polarity and higher dielectric constant, which improves the liquid affinity of the composite flame-retardant separator and helps the ionization of lithium salt, thereby improving the conductivity efficiency.

[0182] Compared with Comparative Example 2, the tensile strength of the examples of the present application is higher than that of Comparative Example 2, which indicates that the addition of aramid is beneficial to improve the mechanical properties of the composite flame-retardant separator.

[0183] In Comparative Example 1, the amount of PVDF is too small, so it cannot form a film.

[0184] Battery Example 1

[0185] The present example provides a battery, and the preparation method is as follows:

[0186] Nickel-cobalt-manganese lithium, conductive agent Super P and binder PVDF were mixed in a mass ratio of 8:1:1, dispersed in organic solvent NMP (N-methyl pyrrolidone), stirred until stable and uniform, and formed into a positive electrode slurry. The positive electrode slurry was scraped onto an aluminum foil with a thickness of 10 μm, dried at 80℃, then heated to 120℃ for further vacuum drying, and then rolled, sliced to form a positive electrode sheet.

[0187] Under the inert atmosphere of glove box, the negative shell, the negative plate, the gasket, the lithium sheet, the electrolyte, the composite flame-retardant separator of Example 1, the positive plate and the positive shell were sequentially assembled, and the assembly was completed under the pressure of 800 kPa for 5 s to obtain a full button type battery.

[0188] Battery Examples 2-11

[0189] Battery Examples 2-11 are basically the same as Battery Example 1, and the only difference is that the composite flame-retardant separator of Example 1 is replaced by the composite flame-retardant separator of Examples 2-11 in Battery Examples 2-11. Based on the detection results of the composite flame-retardant separator comparative examples, Battery Comparative Example 2 and Battery Comparative Example 3 are set.

[0190] Battery Comparative Examples 2 and 3

[0191] Battery Comparative Examples 2 and 3 are basically the same as Battery Example 1, and the only difference is that the composite flame-retardant separator of Example 1 is replaced by the composite flame-retardant separator of Battery Comparative Example 2 and the lithium battery separator of Battery Comparative Example 3 in Battery Comparative Examples 2 and 3.

[0192] The capacity retention rates of Battery Examples 1-11, Battery Comparative Example 2 and Battery Comparative Example 3 are tested respectively, and the data results are shown in Table 2.

[0193] The test method of the capacity retention rate (cycle curve) is that the battery is charged at 25℃ with a constant current and constant voltage to 4.2V at 0.33C, and then discharged with a constant current to 3.0V at 0.5C, which is 1 cycle, and the remaining capacity is the capacity retention rate, and the cycle number and capacity retention rate of each battery are compared.

[0194] Table 2

[0195] From Table 2, it can be seen that:

[0196] Compared with Battery Comparative Example 2, the composite flame-retardant separator prepared by Battery Examples 1-11 of the application is applied to the battery, and the cycle number of Battery Examples 1-11 is much higher than that of Battery Comparative Example 2, which indicates that the service life of the battery of the application is longer; the capacity retention rate of Battery Examples 1-11 in 100 cycles is higher than that of Battery Comparative Example 2, which indicates that the capacity retention rate of the battery of the application in 100 cycles is better, and the cycle life is also longer.

[0197] Compared with Battery Comparative Example 3, i.e. commercial separator, the flame-retardant separator can still maintain a high capacity retention rate after a long time of cycling; at the same time, it can be obviously seen from Table 2 that the capacity retention rate of the battery of the application in 100 cycles is better, and the cycle life is also longer.

[0198] The composite flame-retardant diaphragm, the preparation method and the application thereof provided by the embodiments of the present application are described in detail above, and the principles and implementation manners of the present application are described by using specific examples. The above description of the embodiments is only used to help understand the method of the present application and its core idea; meanwhile, for those skilled in the art, the specific implementation manners and application ranges will be changed according to the idea of the present application. In summary, the content of the present description should not be understood as a limitation of the present application.

Claims

1. A composite flame retardant separator, wherein, The composite flame-retardant separator comprises a base film, an interface layer and a flame-retardant layer, the interface layer is located between the base film and the flame-retardant layer, the material of the base film comprises fluorine-containing organic matter and toughening agent, the material of the flame-retardant layer comprises aramid fiber, and the material of the interface layer comprises the fluorine-containing organic matter, the toughening agent and the aramid fiber.

2. The composite flame retardant separator of claim 1, wherein, The interface layer has a reticular structure.

3. The composite flame retardant separator of claim 1, wherein, One or more of the following features (1) to (3) are included: (1) the fluorine-containing organic matter comprises one or more of polyvinylidene fluoride, polyvinylidene fluoride-hydrofluoric acid copolymer and polyvinylidene fluoride-trifluoroethylene copolymer; (2) the toughening agent comprises one or more of silicon carbide whisker, silicon nitride whisker, glass fiber and polymethyl methacrylate; (3) the aramid fiber comprises one or more of meta-aramid fiber and para-aramid fiber.

4. The composite flame retardant separator of claim 1, wherein, In the base film, the mass ratio of the fluorine-containing organic matter to the toughening agent is (0.6-0.9):(0.01-0.5).

5. The composite flame retardant separator of claim 1, wherein, The flame-retardant layer further comprises a solid electrolyte, and the solid electrolyte comprises one or more of LATP and doped or undoped LLZO.

6. The composite flame retardant separator of claim 5, wherein, One or more of the following features (1) to (3) are included: (1) the general formula of the doped LLZO is Li 7-x La3Zr 2-x M x O 12 wherein 0.25≤x<2, the doping element M includes one or more of Ta, Ga, Al, Nb; (2) the doped LLZO comprises Li 6.7 La3Zr 1.7 Ta 0.3 O 12 , Li 6.5 La3Zr 1.5 Ga 0.5 O 12 , Li 6.2 La3Zr 1.2 Al 0.8 O 12 , Li6La3ZrNbO 12 , Li 5.8 La3Zr 0.8 Ta 1.2 O 12 , Li 5.5 La3Zr 0.5 Nb 1.5 O 12 , Li 5.4 La3Zr 0.4 Ga 1.6 O 12 , Li 5.2 La3Zr 0.2 Ta 1.8 O 12 , Li 5.1 La3Zr 0.1 Nb 1.9 O 12 , Li 6.75 La3Zr 1.75 Nb 0.25 O 12、 Li 5.8 La3Zr 1.4 Ta 0.6 Al 0.2 O 12 one or more of (3) in the flame-retardant layer, the mass ratio of the solid electrolyte to the aramid fiber is (1-10):

1.

7. The composite flame retardant separator of claim 1, wherein, One or more of the following features (1) to (4) are included: (1) the thickness of the composite flame-retardant separator is 8-24 μm; (2) the thickness of the base film is 7-19 μm; (3) the thickness of the interface layer is 100-200 nm; (4) the thickness of the flame-retardant layer is 1-4 μm.

8. A method of making a composite flame retardant separator, wherein, The method comprises: providing a pre-prepared base film, the material of the pre-prepared base film comprising fluorine-containing organic matter and toughening agent; providing a second mixed solution, the second mixed solution comprising aramid fiber; and arranging the second mixed solution on the pre-prepared base film, wherein part of the second mixed solution penetrates into the upper surface of the pre-prepared base film, forming a base film and an interface layer combined with the base film; the second mixed solution that does not penetrate into the pre-prepared base film forms a flame-retardant layer on the interface layer, obtaining a composite flame-retardant separator.

9. The production method according to claim 8, wherein The method for preparing the pre-prepared base film comprises: providing a first mixed solution, the first mixed solution comprising fluorine-containing organic matter, toughening agent and a first solvent; providing a substrate, and arranging the first mixed solution on the substrate, obtaining a pre-prepared base film.

10. The production method according to claim 9, wherein The second mixed solution further comprises a solid electrolyte, a dispersing agent and a second solvent.

11. The production method according to claim 10, wherein One or more of the following features (1) to (6) are included: (1) the first solvent and the second solvent each independently comprise one or more of N-methyl pyrrolidone, dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, acetone, dichloroethane, chloroform, ethanol, isopropanol and toluene; (2) the dispersing agent comprises one or more of polyacrylamide, polyvinylpyrrolidone, carboxymethyl cellulose and acrylic resin; (3) the fluorine-containing organic matter comprises one or more of polyvinylidene fluoride, polyvinylidene fluoride-hydrofluoric acid copolymer and polyvinylidene fluoride-trifluoroethylene copolymer; (4) the toughening agent comprises one or more of silicon carbide whisker, silicon nitride whisker, glass fiber and polymethyl methacrylate; (5) the aramid fiber comprises one or more of meta-aramid fiber and para-aramid fiber; and (6) in the base film, the mass ratio of the fluorine-containing organic matter to the toughening agent is (0.6-0.9):(0.01-0.5). (5) the solid-state electrolyte comprises one or more of LATP, doped or undoped LLZO, wherein the doping element in the doped LLZO comprises one or more of tantalum, gallium, aluminum, and niobium; (6) the aramid fiber comprises one or more of meta-aramid fiber and para-aramid fiber. One or more of the following features (1) to (5) are included:

12. The production method according to claim 10, wherein, (1) the mass ratio of the fluorine-containing organic matter and the toughening agent is (0.6-0.9):(0.01-0.5); (2) in the first mixed solution, the mass concentration of the fluorine-containing organic matter is 89.9-134.8 mg / mL; (3) the mass ratio of the solid-state electrolyte and the aramid fiber is (1-10):1; (4) the mass ratio of the dispersant and the second solvent is 1:(200-1000); (5) in the second mixed solution, the mass concentration of the solid-state electrolyte is 17.236-237 mg / mL. One or more of the following features (1) to (5) are included:

13. The method of making according to claim 10, wherein, (1) the method of disposing the first mixed solution on the substrate comprises first coating; (2) after the first mixed solution is disposed on the substrate, first phase conversion and drying are further included to obtain a pre-prepared base film; (3) the method of providing the second mixed solution comprises dispersing the solid-state electrolyte and the dispersant in the second solvent, and then adding the aramid fiber and continuing to stir; (4) the method of disposing the second mixed solution on the pre-prepared base film comprises second coating; (5) after the second mixed solution is disposed on the pre-prepared base film, second phase conversion and drying are further included. One or more of the following features (1) to (5) are included:

14. The production method according to claim 13, wherein (1) the temperature of the drying and the drying is independently 40-80°C; (2) the time of the drying and the drying is independently 1-300 min; (3) the dispersing comprises dispersing at a speed of n1 for t1 hours; (4) the stirring comprises stirring at a speed of n2 for t2 hours; (5) the first coating and the second coating each independently comprises one or more of spin coating, spray coating, wire bar coating, and dip coating. One or more of the following features (1) to (2) are included:

15. The method of manufacturing according to claim 14, wherein, (1) the n1 and the n2 are each independently 500-3000 r / min; (2) the t1 and the t2 are each independently 1-6 h. The composite flame-retardant separator comprises a base film, an interface layer, and a flame-retardant layer, the interface layer is located between the base film and the flame-retardant layer, the material of the base film comprises fluorine-containing organic matter and a toughening agent, the material of the flame-retardant layer comprises aramid fiber, and the material of the interface layer comprises the fluorine-containing organic matter, the toughening agent, and the aramid fiber.

16. A battery, the battery comprising a composite flame retardant separator, wherein, The interface layer has a reticular structure.

17. The battery of claim 16, wherein, One or more of the following features (1) to (8) are included:

18. The battery of claim 16, wherein, (1) the fluorine-containing organic matter comprises one or more of polyvinylidene fluoride, polyvinylidene fluoride-hydrofluoric acid copolymer, and polyvinylidene fluoride-trifluoroethylene copolymer; (2) the toughening agent comprises one or more of silicon carbide whisker, silicon nitride whisker, glass fiber, and polymethyl methacrylate; (3) the aramid fiber comprises one or more of meta-aramid fiber and para-aramid fiber; ​ (4) the mass ratio of the fluorine-containing organic matter and the toughening agent in the base film is (0.6-0.9):(0.01-0.5); (5) the thickness of the composite flame-retardant separator is 8-24 μm; (6) the thickness of the base film is 7-19 μm; (7) the thickness of the interface layer is 100-200 nm; (8) the thickness of the flame-retardant layer is 1-4 μm.

19. The battery of claim 16, wherein, The flame-retardant layer further comprises a solid-state electrolyte, and the solid-state electrolyte comprises one or more of LATP, doped or undoped LLZO.

20. The battery of claim 19, wherein, One or more of the following features (1) to (3) are included: (1) the general formula of the doped LLZO is Li 7-x La3Zr 2-x M x O 12 wherein 0.25≤x<2, and the doping element M includes one or more of Ta, Ga, Al, and Nb. (2) the doped LLZO comprises Li 6.7 La3Zr 1.7 Ta 0.3 O 12 , Li 6.5 La3Zr 1.5 Ga 0.5 O 12 , Li 6.2 La3Zr 1.2 Al 0.8 O 12 , Li6La3ZrNbO 12 , Li 5.8 La3Zr 0.8 Ta 1.2 O 12 , Li 5.5 La3Zr 0.5 Nb 1.5 O 12 , Li 5.4 La3Zr 0.4 Ga 1.6 O 12 , Li 5.2 La3Zr 0.2 Ta 1.8 O 12 , Li 5.1 La3Zr 0.1 Nb 1.9 O 12 , Li 6.75 La3Zr 1.75 Nb 0.25 O 12、 Li 5.8 La3Zr 1.4 Ta 0.6 Al 0.2 O 12 one or more of (3) in the flame-retardant layer, the mass ratio of the solid-state electrolyte and the aramid fiber is (1-10):1.

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