A method for in-situ preparation of bismuth oxyhalide-pvdf-based composite solid electrolyte membrane

Abstract

The application discloses a method for preparing in-situ bismuth oxyhalide-PVDF-based composite solid electrolyte membrane, which comprises the following steps: firstly, according to the metering ratio, bismuth salt and organic halide containing alkyl and quaternary ammonium cation are respectively dissolved in an organic solvent under a heating condition to obtain solution 1 and solution 2; then, according to the metering ratio, a polymer containing a PVDF chain segment and a lithium salt are dissolved in the solution 2 containing the bismuth salt under the heating condition to obtain solution 3; finally, the solution 2 and the solution 3 are mixed and reacted under the heating condition to obtain a precursor solution of a composite electrolyte, and the precursor solution of the composite electrolyte is coated and solidified to obtain a composite solid electrolyte. The preparation method solves the problem of insufficient cycle performance of the solid electrolyte caused by the difficulty of uniform dispersion of the bismuth oxyhalide inorganic filler in the polymer matrix, and a preparation method for rapidly preparing the bismuth oxyhalide-PVDF-based composite solid electrolyte membrane is obtained.

Description

Technical Field

[0001] This invention belongs to the field of solid-state battery technology, specifically relating to a method for in-situ preparation of bismuth oxyhalide-PVDF-based composite solid electrolyte membranes. Technical Background

[0002] With rapid technological advancements and the widespread use of various electronic devices, traditional lithium-ion batteries (LIBs) can no longer meet the demand for higher energy densities. Lithium metal batteries (LMBs), due to their relatively high energy density and low reduction potential, have become a promising option for next-generation high-performance batteries. However, safety concerns arising from the irregular growth of lithium dendrites and uncontrollable side reactions in traditional organic flammable liquid electrolytes (LEs) hinder the development of LMBs.

[0003] Solid-state electrolytes (SSEs) have been identified as promising alternatives to lithium dendrites (LEs) due to their superior electrochemical stability and mechanical properties, which can address safety concerns related to Li dendrite growth and interfacial reactions. Among these, PVDF has attracted significant attention due to its ideal mechanical strength, excellent thermal stability, wide voltage window, and superior electrochemical stability. However, PVDF also suffers from some inherent drawbacks, such as low ionic conductivity and susceptibility to crystallization. This can lead to lithium dendrite formation or even "dead lithium" phenomena during battery cycling, thus affecting the battery's cycle performance.

[0004] In our research, we found that when bismuth oxyhalide is introduced into the PVDF matrix as an inorganic filler, it can compete with the phase transition process of polymers containing polyvinylidene fluoride segments during the curing process, thus limiting the formation of pores in the composite solid electrolyte. Secondly, during the competitive phase transition, bismuth oxyhalide can promote the transformation of polymers containing polyvinylidene fluoride segments to the β phase and induce the formation of LiF in polymers containing polyvinylidene fluoride groups during cycling, improving the cycling performance and ionic conductivity of the PVDF matrix. Therefore, it holds promise as an inorganic filler to improve the electrochemical performance of the PVDF matrix. However, because bismuth oxyhalide is composed of alternating bismuth-oxygen and halogen layers, its unique layered structure results in strong interlayer forces between bismuth oxyhalide particles. When mixed with the solid electrolyte precursor solution, problems such as uneven mixing and bismuth oxyhalide agglomeration often occur. This uneven mixing leads to uneven lithium-ion transport and severe side reactions in some areas of the membrane in the prepared composite solid electrolyte, thus affecting the long-cycle performance of the battery.

[0005] How to further improve the preparation process, simplify the preparation procedure, and improve the preparation efficiency based on obtaining a uniform bismuth oxyhalide-PVDF matrix composite solid electrolyte has become the focus of current research. Summary of the Invention

[0006] This invention addresses the problems in the prior art by proposing an in-situ method for preparing bismuth oxyhalide-PVDF-based composite solid electrolyte membranes. This method solves the problems of uneven lithium-ion transport in solid electrolytes due to the difficulty in dispersing bismuth oxyhalide, severe side reactions in some areas of the membrane, and insufficient cycle performance, thus obtaining a method for preparing bismuth oxyhalide-PVDF-based composite solid electrolyte membranes with high cycle performance.

[0007] Firstly, this solution provides a bismuth oxyhalide-PVDF-based composite solid electrolyte membrane, the raw materials of which include bismuth salt, an organic halide containing alkyl groups and positively charged quaternary ammonium cations, a polymer containing PVDF segments, and a lithium salt. The general formula of bismuth oxyhalide is BiOX, where Bi is bismuth, O is oxygen, and X is a halogen element. The halogen element is selected from any one of Cl, Br, I, and F. The mass ratio of bismuth oxyhalide to the polymer containing PVDF segments is selected from (0.01-0.5):1.

[0008] In the in-situ preparation of bismuth oxyhalide-PVDF-based composite solid electrolyte membranes, the β-phase percentage of PVDF was selected from 60%-70%, and the crystallinity was 20%-25%.

[0009] As a further option, the bismuth oxyhalide is selected from any one of BiOCl, BiOBr, BiOI, and BiOF.

[0010] As some preferred options, the bismuth oxyhalide is selected from BiOCl.

[0011] As a further embodiment, the oxidation potential of the polyvinylidene fluoride composite solid electrolyte membrane is greater than or equal to 4.5V.

[0012] As a further embodiment, the oxidation potential of the polyvinylidene fluoride composite solid electrolyte membrane is greater than or equal to 4.6V.

[0013] As some preferred embodiments, the oxidation potential of the polyvinylidene fluoride composite solid electrolyte membrane is greater than or equal to 4.7V.

[0014] In a second aspect, the present invention provides a method for in-situ preparation of bismuth oxyhalide-PVDF-based composite solid electrolyte membranes, comprising the following steps:

[0015] S1: According to the stoichiometric ratio, bismuth salt and organic halide containing alkyl and quaternary ammonium cations are dissolved in an organic solvent under heating conditions to obtain solution 1 and solution 2.

[0016] S2: According to the stoichiometric ratio, the polymer containing PVDF segments and lithium salt are dissolved in solution 2 under heating to obtain solution 3;

[0017] S3: After mixing and reacting solutions 1 and 3 under heating conditions, a precursor solution of the composite electrolyte is obtained. The precursor solution of the composite electrolyte is then coated and cured to obtain a composite solid electrolyte membrane.

[0018] As a further option, in step S1, the molar ratio of bismuth salt to organohalide containing alkyl and quaternary ammonium cations is selected from 1:(2-2.5).

[0019] As a further embodiment, in step S1, the mass ratio of the total mass of the bismuth salt and the organic halide containing alkyl and quaternary ammonium cations to the mass of the organic solvent is selected from (0.01-0.5):(5-20).

[0020] As a further option, in step S1, the bismuth salt is selected from either oxyacid bismuth salts or organic acid bismuth salts.

[0021] As a further option, in step S1, the organohalides containing alkyl and quaternary ammonium cations are selected from any one of organohalides containing C2-C20 alkyl and quaternary ammonium cations.

[0022] As a further embodiment, in step S1, the organohalides containing C2-C20 alkyl groups and quaternary ammonium cations are selected from organohalides that have structural symmetry and contain C4-C20 alkyl groups and quaternary ammonium cations.

[0023] As a further embodiment, in step S1, the organohalides having structural symmetry and containing C4-C20 alkyl groups and quaternary ammonium cations are selected from ammonium halide salts having structural symmetry and containing C4-C20 alkyl groups and quaternary ammonium cations.

[0024] As a further option, in step S1, the ammonium halide salt having a symmetrical structure and containing C4-C20 alkyl groups and quaternary ammonium cations is not limited in principle, and can be selected, for example, from dioctadecyldimethylammonium chloride. Didodecyl dimethyl ammonium chloride Dimethyl ditetradecylammonium chloride Dioctadecyl dimethyl ammonium bromide Dimethyl di(octadecyl)ammonium iodide Tetrabutylammonium chloride Tetrapentylammonium chloride Tetrabutylammonium iodide Tetrahexylammonium iodide Tetrahedralammonium iodide Any one of them.

[0025] As some preferred parameters, in step S1, when the bismuth salt and the organic halide containing alkyl and quaternary ammonium cations are dissolved in an organic solvent, the heating temperature is selected from 40℃-50℃.

[0026] As a further option, in step S2, the mass ratio of the polymer containing PVDF segments to the lithium salt is selected from 1:(0.25-2).

[0027] As a further option, the mass ratio of the polymer containing PVDF segments to the organic solvent is selected from 1:(5-20).

[0028] As a further embodiment, the polymer containing PVDF segments is selected from polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), and mixtures of polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP).

[0029] As a further option, in the mixture of PVDF and PVDF-HFP, the mass ratio of PVDF to PVDF-HFP is selected from 3:1.

[0030] As a further option, the lithium salt is selected from any one or more of LiPF6, LiF, LiBF4, LiTFSI, LiCl, Li2SO4, LiOAc, LiNO3, LiPO2F2, LiCF3SO3, Li2CO3, LiFSI, LiBOB, and LiDFOB.

[0031] As a further option, the lithium salt is selected from LiTFSI.

[0032] As a further option, the organic solvent is selected from any one or more of amide solvents, pyrrolidone solvents, and ether solvents.

[0033] As some preferred parameters, in step S2, when the polymer containing PVDF segments and lithium salt are dissolved in solution 1 containing bismuth salt, the heating temperature is selected from 40℃-50℃ and the heating time is greater than or equal to 6h.

[0034] As some preferred parameters, in step S2, when the polymer containing PVDF segments and lithium salt are dissolved in solution 1 containing bismuth salt, the heating temperature is selected from 40℃-50℃ and the heating time is selected from 6h-10h.

[0035] As some preferred parameters, in step S3, the temperature of the mixing reaction of solution 1 and solution 3 is selected from 40℃-50℃, and the mixing reaction time is selected from 22h-26h.

[0036] As a further option, in step S3, the coating method is not limited in principle. Technicians can choose the appropriate coating method according to their needs, such as mechanical coating.

[0037] As a further embodiment, the mechanical coating step is as follows: pour solution 3 onto a glass plate, and then adjust the thickness of the doctor blade to 300 μm for uniform coating.

[0038] As a further option, the curing time is selected from 1.5h-3h.

[0039] As a further option, the vacuum drying temperature in step S3 is selected from 60℃-80℃.

[0040] As a further option, the vacuum drying time in step S3 is selected from 20 hours or more.

[0041] Thirdly, this solution provides a battery, including a bismuth oxyhalide-PVDF-based composite solid electrolyte membrane prepared by a method for in-situ preparation of a bismuth oxyhalide-PVDF-based composite solid electrolyte membrane.

[0042] As a further option, the battery is selected from either solid-state batteries or semi-solid-state batteries.

[0043] As a further embodiment, the battery includes a positive electrode and a negative electrode.

[0044] As a further embodiment, the positive electrode sheet includes a positive active material, a positive current collector, a positive conductive agent, and a positive binder.

[0045] As a further option, the positive electrode active material is selected from LiMO2 and lithium nickel cobalt manganese oxide (LiNi). x Mn y Co z O2, Lithium nickel cobalt aluminum oxide (LiNi) p Co q Al f O2, lithium-rich manganese-based cathode materials: Li 1+a Ni b Co c Mn d TM 1-b-c-d O2, lithium nickel manganese oxide (Li) k XO2, Lithium manganese iron phosphate (Li) e Mn 1-g-j Fe g Z jPO4, wherein M is selected from any one of Co, Li, and Mn; TM is selected from any one or more of nickel, cobalt, manganese, iron, titanium, chromium, vanadium, molybdenum, magnesium, and copper; X is selected from at least one of Ni, Co, and Mn; Z is selected from at least one of B, Mg, Al, Si, Ca, Ti, V, Cr, Co, Ni, Cu, Zn, Y, Zr, Nb, and Mo, 0.1≤x≤0.8, 0.1≤y≤0.3, 0.1≤z≤0.3, x+y+z=1, 0.6≤p≤0.9, 0.05≤q≤0.2, 0.03≤f≤0.1, 0 <a≤0.5,0<b≤0.3,0<c≤0.3,0.2<d≤0.7,0<k<1,1-b-c-d≥0,0.8<e<1.2,0.5<1-g-j<1,0.05<g<0.5,0<j<0.2。

[0046] As a further embodiment, the positive current collector is selected from copper, aluminum, titanium, nickel, tantalum, niobium, hafnium, zirconium, zinc, tungsten, bismuth, antimony, gold, silver, iron, platinum, chromium, tin, indium, alloys containing one or more of these, and may also be mentioned as one or more metals selected from alloys;

[0047] As a further option, the positive electrode conductive agent is selected from any one or more of carbon materials, metallic materials, and conductive polymers.

[0048] As a further option, the positive electrode adhesive is selected from at least one of thermoplastic resins, acrylic resins, sodium carboxymethyl cellulose, and styrene-butadiene rubber.

[0049] As a further embodiment, the negative electrode sheet includes a negative electrode active material, a negative electrode current collector, a negative electrode conductive agent, and a negative electrode binder.

[0050] As a further option, the negative electrode active material is selected from natural graphite, artificial graphite, mesophase microcarbon spheres (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composites, Li-Sn alloys, Li-Sn-O alloys, Sn, SnO, SnO2, and spinel-structured lithiated TiO2-Li4Ti5O. 12 One or more of Li-Al alloys

[0051] As a further option, the negative electrode current collector is not limited in principle, and can be any one of aluminum, nickel, tin, copper and stainless steel.

[0052] As a further option, the negative electrode conductive agent is selected from carbon materials.

[0053] As a further option, the carbon material used as the negative electrode conductive agent is selected from any one or more of carbon black, Super P, activated carbon, graphite, graphene, multi-walled carbon nanotubes, single-walled carbon nanotubes, carbon fibers, conductive carbon black, carbon nanospheres, ellipsoidal carbon, hard carbon, amorphous carbon, and silicon carbide.

[0054] As a further option, the negative electrode adhesive is selected from any one or more of polymers, rubbers, cellulose derivatives, and resins.

[0055] Fourthly, this solution provides an energy storage device composed of multiple batteries for storing and releasing electrical energy.

[0056] Compared with the prior art, the present invention has at least the following beneficial effects:

[0057] This invention significantly improves the cycle efficiency and ionic conductivity of PVDF-based solid electrolytes by introducing bismuth oxyhalide as an inorganic filler, extending service life and enhancing overall performance. By incorporating the bismuth oxyhalide precursor into the polymer matrix and achieving in-situ generation of bismuth oxyhalide during stirring, uniform distribution of bismuth oxyhalide within the PVDF matrix is ​​ensured, effectively improving filler dispersibility and resolving issues such as bismuth oxyhalide agglomeration. Furthermore, the method provided by this invention simplifies the preparation steps, improves efficiency, and shortens preparation time, demonstrating broad prospects for industrial application. Attached Figure Description

[0058] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0059] Figure 1 The XRD pattern of BiOCl synthesized in Comparative Example 1;

[0060] Figure 2 The image shows the XRD pattern of the bismuth oxyhalide-PVDF-based composite solid electrolyte membrane synthesized in Example 1.

[0061] Figure 3 middle, Figure 3 a represents solution 1. Figure 3 b is solution 2. Figure 3 c is a mixture of solution 1 and solution 2. Figure 3 d represents the mixture of solution 1 and solution 2 after standing for 5 hours;

[0062] Figure 4 This is a cycle diagram of Example 1 at 0.5C.

[0063] Figure 5 This is an electrochemical window diagram of Example 1 and Comparative Example 1. Detailed Implementation

[0064] For ease of understanding, the present invention will be described more fully below, and embodiments of the present invention will be given, but this does not limit the scope of the present invention.

[0065] The following are descriptions of terms or words, and unless otherwise defined, all technical and scientific terms used herein have the meanings commonly understood by one of ordinary skill in the art to which this invention pertains.

[0066] In this article, the term "bismuth oxyhalide" refers to the product obtained by the chemical reaction of bismuth salts, organohalides containing alkyl and quaternary ammonium cations.

[0067] In the first aspect, this solution provides a bismuth oxyhalide-PVDF-based composite solid electrolyte membrane, the raw materials of which include bismuth salt, an organic halide containing alkyl and quaternary ammonium cations, a polymer containing PVDF segments, and lithium salt. The general formula of bismuth oxyhalide is BiOX, where Bi is bismuth, O is oxygen, and X is a halogen element. The halogen element is selected from any one of Cl, Br, I, and F. The mass ratio of bismuth oxyhalide to the polymer containing PVDF segments is selected from (0.01-0.5):1.

[0068] In the in-situ preparation of bismuth oxyhalide-PVDF-based composite solid electrolyte membranes, the β-phase percentage of PVDF was selected from 60%-70%, and the crystallinity was 20%-25%.

[0069] As some optional parameters, the bismuth oxyhalide is selected from any one of BiOCl, BiOBr, BiOI, and BiOF.

[0070] As some preferred parameters, the bismuth oxyhalide is selected from BiOCl.

[0071] As some optional parameters, the oxidation potential of the polyvinylidene fluoride composite solid electrolyte membrane is greater than or equal to 4.5V.

[0072] As some optional parameters, the oxidation potential of the polyvinylidene fluoride composite solid electrolyte membrane is greater than or equal to 4.6V.

[0073] As some preferred parameters, the oxidation potential of the polyvinylidene fluoride composite solid electrolyte membrane is greater than or equal to 4.7V.

[0074] In a second aspect, the present invention provides a method for in-situ preparation of bismuth oxyhalide-PVDF-based composite solid electrolyte membranes, comprising the following steps:

[0075] S1: According to the stoichiometric ratio, bismuth salt and organic halide containing alkyl and quaternary ammonium cations are dissolved in an organic solvent under heating conditions to obtain solution 1 and solution 2.

[0076] S2: According to the stoichiometric ratio, the polymer containing PVDF segments and lithium salt are dissolved in solution 2 under heating to obtain solution 3;

[0077] S3: After mixing and reacting solutions 1 and 3 under heating conditions, a precursor solution of the composite electrolyte is obtained. The precursor solution of the composite electrolyte is then coated and cured to obtain a composite solid electrolyte membrane.

[0078] To optimize the performance of PVDF-based solid electrolytes, inorganic fillers were introduced into the PVDF matrix. During experiments, we found that compared to inorganic fillers such as SiO2 and TiO2, using bismuth oxyhalide as an inorganic filler effectively optimized the electrochemical performance of the PVDF-based composite solid electrolyte membrane, improving cycle efficiency and ionic conductivity. This is likely because during the curing process of the composite solid electrolyte membrane, bismuth oxyhalide competes with the polymer containing polyvinylidene fluoride segments for phase transition, effectively suppressing porosity formation. Furthermore, during this phase transition competition, bismuth oxyhalide promotes the polymer's transformation from other phases to the β phase and induces the formation of LiF from polyvinylidene fluoride groups during cycling. This not only improves the cycle performance of the PVDF matrix but also increases its ionic conductivity. Therefore, bismuth oxyhalide shows promise as an inorganic filler to significantly improve the electrochemical performance of the PVDF matrix.

[0079] However, during the experiments, we also found that achieving uniform dispersion of bismuth oxyhalides in a PVDF matrix is ​​not easy. Existing preparation methods are often very complex, inefficient, and time-consuming. Therefore, this paper proposes a method for preparing a composite solid electrolyte membrane. Utilizing the characteristic that bismuth salts and organic halides containing alkyl and quaternary ammonium cations are soluble in organic solvents under heating conditions (40℃-60℃), bismuth salts and organic halides containing alkyl and quaternary ammonium cations are dissolved separately in organic solvents under heating conditions. Furthermore, a polymer containing PVDF segments and a lithium salt are added to solution 2. Subsequently, solutions 1 and 2 are mixed, achieving in-situ growth of bismuth oxyhalides in the matrix material, thus obtaining a composite solid electrolyte membrane with uniformly distributed bismuth oxyhalides. In this method, the organic halides containing alkyl and quaternary ammonium cations can both initiate the formation of bismuth oxyhalides from bismuth salts and, due to their structure, act as surfactants, further promoting oxyhalogenation while generating bismuth oxyhalides. The dispersion of bismuth; secondly, in this scheme, bismuth salt and organic halides containing alkyl and quaternary ammonium cations are dissolved in organic solvents to avoid premature formation of bismuth oxyhalides, while better achieving the dissolution of bismuth salt and organic halides containing alkyl and quaternary ammonium cations. Next, after dissolving the organic halides containing alkyl and quaternary ammonium cations in organic solvents to obtain solution 2, this scheme further adds a polymer containing PVDF segments and a lithium salt to solution 2. This is because, compared to solution 1, adding the polymer containing PVDF segments and the lithium salt to solution 2 allows the polymer containing PVDF segments to form an interwoven, uniform internet structure with the organic halides containing alkyl and quaternary ammonium cations, enabling the subsequent bismuth oxyhalides to be directly anchored and generated on the internet structure, thereby achieving uniform distribution of bismuth oxyhalides in the composite solid electrolyte membrane. Finally, this scheme thoroughly mixes solutions 1 and 3 and reacts and solidifies, thus obtaining a composite solid electrolyte membrane with uniformly distributed bismuth oxyhalides, and providing a simple and efficient preparation method.

[0080] As some optional parameters, in step S1, the molar ratio of the bismuth salt to the organohalide containing alkyl and quaternary ammonium cations is selected from 1:(2-2.5). When the molar ratio of the bismuth salt to the organohalide containing alkyl and quaternary ammonium cations is selected from 1:(2-2.5), the bismuth salt can be ensured to react completely.

[0081] As some optional parameters, in step S1, the mass ratio of the total mass of the bismuth salt and the organic halide containing alkyl and quaternary ammonium cations to the mass of the organic solvent is selected from (0.01-0.5):(5-20).

[0082] As some optional parameters, in step S1, the bismuth salt is selected from any one of oxyacid bismuth salts and organic acid bismuth salts.

[0083] As some optional parameters, the oxyacid bismuth salt is selected from any one of bismuth nitrate pentahydrate, bismuth sulfate, bismuth phosphate, and bismuth carbonate.

[0084] As some optional parameters, the organic acid bismuth salt is selected from any one of bismuth acetate, bismuth citrate, and bismuth oxalate.

[0085] As some optional parameters, in step S1, the organohalides containing alkyl and quaternary ammonium cations are selected from any one of organohalides containing C2-C20 alkyl and quaternary ammonium cations.

[0086] As optional parameters, in step S1, the organohalides containing C2-C20 alkyl groups and quaternary ammonium cations are selected from organohalides with symmetrical structures and containing C4-C20 alkyl groups and quaternary ammonium cations. Asymmetric molecules tend to form irregular aggregates more easily, leading to low local solubility or uneven distribution. Symmetrical structures can effectively avoid this situation. Therefore, in this scheme, organohalides with symmetrical structures and containing C4-C20 alkyl groups and quaternary ammonium cations are selected, which helps to fully avoid excessive local aggregation of bismuth salts, thereby further improving the dispersion of bismuth oxyhalides in the matrix.

[0087] As some optional parameters, in step S1, the organohalides having structural symmetry and containing C4-C20 alkyl groups and quaternary ammonium cations are selected from ammonium halide salts having structural symmetry and containing C4-C20 alkyl groups and quaternary ammonium cations.

[0088] As some optional parameters, in step S1, the ammonium halide salt having a symmetrical structure and containing C4-C20 alkyl groups and quaternary ammonium cations is not limited in principle, and can be selected, for example, from dioctadecyldimethylammonium chloride. Didodecyl dimethyl ammonium chloride Dimethyl ditetradecylammonium chloride Dioctadecyl dimethyl ammonium bromide Dimethyl di(octadecyl)ammonium iodide Tetrabutylammonium chloride Tetrapentylammonium chloride Tetrabutylammonium iodide Tetrahexylammonium iodide Tetrahedralammonium iodide Any one of them.

[0089] As some preferred parameters, in step S1, when the bismuth salt and the organic halide containing alkyl and quaternary ammonium cations are dissolved in an organic solvent, the heating temperature is selected from 40℃-50℃.

[0090] As some optional parameters, in step S2, the mass ratio of the polymer containing PVDF segments to the lithium salt is selected from 1:(0.25-2).

[0091] As some optional parameters, the mass ratio of the polymer containing PVDF segments to the organic solvent is selected from 1:(5-20).

[0092] As some optional parameters, the polymer containing PVDF segments is selected from polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), and mixtures of polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP).

[0093] As some optional parameters, the mass ratio of PVDF to PVDF-HFP in the mixture of PVDF and PVDF-HFP is selected from 3:1.

[0094] As some optional parameters, the lithium salt is selected from any one or more of LiPF6, LiF, LiBF4, LiTFSI, LiCl, Li2SO4, LiOAc, LiNO3, LiPO2F2, LiCF3SO3, Li2CO3, LiFSI, LiBOB, and LiDFOB.

[0095] As some optional parameters, the lithium salt is selected from LiTFSI.

[0096] As some optional parameters, the organic solvent is selected from any one or more of amide solvents, pyrrolidone solvents, and ether solvents.

[0097] As some optional parameters, the amide solvent is selected from any one or more of N,N-dimethylformamide (DMF), N,N-diethylformamide (DEMF), N,N-dimethylpropionamide (DMPA), N-methyl-N-ethylformamide (MEMA), N-ethyl-N-methylformamide (EMEA), N-phenylpropionamide (NPA), N-ethyl-N,N-dimethylformamide (EDMF), and N,N-dimethylphthalamide (DMPhF).

[0098] As some optional parameters, the pyrrolidone solvent is selected from N-methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP), N-butylpyrrolidone (NBP), N-isopropylpyrrolidone (NIP), N-octylpyrrolidone (NSP), and N-hexadecylpyrrolidone (C). 16 Any one or more of the following: -Pyrrolidone, N-methyl-2-pyrrolidone (NMP-2), and N,N-dimethyl-2-pyrrolidone (DM-2P).

[0099] As some optional parameters, the ether solvent is selected from any one or more of dimethyl carbonate (DMC), diethyl carbonate (DEC), tetrahydrofuran (THF), dimethoxyethane (DME), ethoxyethane (EOE), ethylene oxide (EO), and phenyl ether.

[0100] As some preferred parameters, in step S2, when the polymer containing PVDF segments and lithium salt are dissolved in solution 1 containing bismuth salt, the heating temperature is selected from 40℃-50℃ and the heating time is greater than or equal to 6h.

[0101] As some preferred parameters, in step S2, when the polymer containing PVDF segments and lithium salt are dissolved in solution 1 containing bismuth salt, the heating temperature is selected from 40℃-50℃ and the heating time is selected from 6h-10h.

[0102] As some preferred parameters, in step S3, the temperature of the mixing reaction of solution 1 and solution 3 is selected from 40℃-50℃, and the mixing reaction time is selected from 22h-26h.

[0103] As some optional parameters, the coating method in step S3 is not limited in principle. Technicians can choose the appropriate coating method according to their needs, such as mechanical coating.

[0104] As some optional parameters, the mechanical coating step is as follows: pour solution 3 onto a glass plate, and then adjust the doctor blade thickness to 300 μm for uniform coating.

[0105] As some optional parameters, the curing time is selected from 1.5h to 3h.

[0106] As some optional parameters, the vacuum drying temperature in step S3 is selected from 60℃-80℃.

[0107] As some optional parameters, the vacuum drying time in step S3 is selected from 20 hours or more.

[0108] Thirdly, this solution provides a battery, including a bismuth oxyhalide-PVDF-based composite solid electrolyte membrane prepared by a method for in-situ preparation of a bismuth oxyhalide-PVDF-based composite solid electrolyte membrane.

[0109] As some optional parameters, the battery is selected from either solid-state batteries or semi-solid-state batteries.

[0110] As some optional parameters, the battery includes a positive electrode and a negative electrode.

[0111] As some optional parameters, the positive electrode includes a positive active material, a positive current collector, a positive conductive agent, and a positive binder.

[0112] As some optional parameters, the positive electrode active material is selected from LiMO2, lithium nickel cobalt manganese oxide (LiNi), etc. x Mn y Co z O2, Lithium nickel cobalt aluminum oxide (LiNi) p Co q Al f O2, lithium-rich manganese-based cathode materials: Li 1+a Ni b Co c Mn d TM 1-b-c-d O2, lithium nickel manganese oxide (Li) k XO2, Lithium manganese iron phosphate (Li) e Mn 1-g-j Fe g Z j PO4, wherein M is selected from any one of Co, Li, and Mn; TM is selected from any one or more of nickel, cobalt, manganese, iron, titanium, chromium, vanadium, molybdenum, magnesium, and copper; X is selected from at least one of Ni, Co, and Mn; Z is selected from at least one of B, Mg, Al, Si, Ca, Ti, V, Cr, Co, Ni, Cu, Zn, Y, Zr, Nb, and Mo, 0.1≤x≤0.8, 0.1≤y≤0.3, 0.1≤z≤0.3, x+y+z=1, 0.6≤p≤0.9, 0.05≤q≤0.2, 0.03≤f≤0.1, 0 <a≤0.5,0<b≤0.3,0<c≤0.3,0.2<d≤0.7,0<k<1,1-b-c-d≥0,0.8<e<1.2,0.5<1-g-j<1,0.05<g<0.5,0<j<0.2。

[0113] As some optional parameters, the positive current collector is selected from copper, aluminum, titanium, nickel, tantalum, niobium, hafnium, zirconium, zinc, tungsten, bismuth, antimony, gold, silver, iron, platinum, chromium, tin, indium, alloys containing one or more of these, and may be mentioned as one or more metals selected from alloys.

[0114] As some optional parameters, the positive electrode conductive agent is selected from any one or more of carbon materials, metallic materials, and conductive polymers.

[0115] As some optional parameters, the carbon material is selected from any one or more of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, and carbon fiber.

[0116] As some optional parameters, the metal material is selected from any one or more of copper, nickel, aluminum, and silver.

[0117] As some optional parameters, the conductive polymer is selected from one or more of polyfluorene (PF), polyaniline (PANI), polypyrrole (PPy), polythiophene (PTh), polyethylene dioxythiophene (PEDOT), polyethylene dioxythiophene:polystyrene sulfonate (PEDOT:PSS), and polyacetylene (PA).

[0118] As some optional parameters, the positive electrode adhesive is selected from at least one of thermoplastic resins, acrylic resins, sodium carboxymethyl cellulose, and styrene-butadiene rubber.

[0119] As a further embodiment, the thermoplastic resin includes at least one selected from polyvinylidene fluoride, copolymers of vinylidene fluoride, polytetrafluoroethylene, copolymers of vinylidene fluoride-hexafluoropropylene, copolymers of tetrafluoroethylene-hexafluoropropylene, copolymers of tetrafluoroethylene-perfluoroalkyl vinyl ethers, copolymers of ethylene-tetrafluoroethylene, copolymers of vinylidene fluoride-tetrafluoroethylene, copolymers of vinylidene fluoride-trifluoroethylene, copolymers of vinylidene fluoride-trichloroethylene, copolymers of vinylidene fluoride-fluorinated vinylidene, copolymers of vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene, thermoplastic polyimide, polyethylene, and polypropylene.

[0120] As some optional parameters, the negative electrode sheet includes a negative electrode active material, a negative electrode current collector, a negative electrode conductive agent, and a negative electrode binder.

[0121] As some optional parameters, the negative electrode active material is selected from natural graphite, artificial graphite, mesophase microcarbon spheres (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composites, Li-Sn alloys, Li-Sn-O alloys, Sn, SnO, SnO2, and spinel-structured lithiated TiO2-Li4Ti5O. 12 One or more of Li-Al alloys

[0122] As some optional parameters, the negative electrode current collector is not limited in principle, and can be any one of aluminum, nickel, tin, copper and stainless steel.

[0123] As some optional parameters, the negative electrode conductive agent is selected from carbon materials.

[0124] As some optional parameters, the carbon material used as the negative electrode conductive agent is selected from any one or more of carbon black, Super P, activated carbon, graphite, graphene, multi-walled carbon nanotubes, single-walled carbon nanotubes, carbon fibers, conductive carbon black, carbon nanospheres, ellipsoidal carbon, hard carbon, amorphous carbon, and silicon carbide.

[0125] As some optional parameters, the negative electrode adhesive is selected from any one or more of polymers, rubbers, cellulose derivatives, and resins.

[0126] As some optional parameters, the polymer is selected from any one or more of polyvinyl alcohol, polyvinyl chloride, polyvinyl fluoride, polyvinylidene 1,1-difluoroethylene, polyvinylpyrrolidone, polyethylene, polypropylene, polyimide, polyacrylic acid, polyvinyl chloride, polytetrafluoroethylene, and polyvinylidene fluoride.

[0127] As some optional parameters, the rubber type is selected from any one or more of styrene-butadiene rubber, ethylene propylene diene monomer (EPDM) rubber, and fluororubber.

[0128] As some optional parameters, the cellulose derivatives are selected from any one or more of carboxymethyl cellulose, hydroxypropyl cellulose, and diacetyl cellulose.

[0129] As some optional parameters, the resin is selected from epoxy resin, styrene or more.

[0130] Fourthly, this solution provides an energy storage device composed of multiple batteries for storing and releasing electrical energy.

[0131] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application and do not represent all possible embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0132] The chemical raw materials used in the following examples and comparative examples are all prior art and were obtained commercially. The experimental apparatus and testing equipment used in the following examples and comparative examples are all conventional equipment in the art, and there are no special requirements or limitations.

[0133] Example 1

[0134] S1: BiOCl was prepared using bis(octadecyl dimethyl ammonium chloride) (DODAC) and bismuth nitrate pentahydrate (Bi(NO3)3·5H2O). PVDF was used as the polymer containing PVDF segments. 0.1 g of bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) was dissolved in 2.5 g of DMF at 45 °C to obtain solution 1. 0.27 g of bis(octadecyl dimethyl ammonium chloride) (DODAC) was dissolved in 5 g of DMF at a constant temperature of 45 °C to obtain solution 2.

[0135] S2: Add 0.5g of PVDF and 0.5g of LiTFSI to solution 2, and then stir at 45℃ for 6h to obtain solution 3;

[0136] S3: Mix solutions 1 and 3 and stir at 45°C for 24 hours to obtain a precursor solution of the composite electrolyte. Then, mechanically coat the precursor solution of the composite electrolyte to a thickness of 400 μm. After coating, vacuum cure at 70°C for 24 hours to obtain a composite solid electrolyte membrane with a thickness of 70 μm.

[0137] The composite solid electrolyte membranes prepared above were assembled into batteries. Stainless steel sheets were used as both positive and negative electrodes to assemble SS||SS batteries; lithium metal was used as the negative electrode and stainless steel as the positive electrode to assemble Li||SS batteries; lithium metal was used as both positive and negative electrodes to prepare Li||Li symmetric batteries; and lithium metal was used as the negative electrode and NCM811 or LFP as the positive electrode to prepare Li||NCM811 / LFP full cells. All operations were performed in an argon-filled glove box.

[0138] Example 2

[0139] The synthesis method and preparation conditions are the same as in Example 1, except that the preparation temperature of solutions 1, 2, and 3, as well as the precursor solution of the composite electrolyte, is 40°C.

[0140] Example 3

[0141] The synthesis method and preparation conditions are the same as in Example 1, except that DODAC is replaced with tributylmethylammonium chloride.

[0142] Example 4

[0143] The synthesis method and preparation conditions are the same as in Example 1, except that bismuth phosphate is used instead of Bi(NO3)3·5H2O.

[0144] Example 5

[0145] The synthesis method and preparation conditions are the same as in Example 1, except that bismuth acetate is used instead of Bi(NO3)3·5H2O.

[0146] Example 6

[0147] The synthesis method and preparation conditions are the same as in Example 1, except that dimethyl di(octadecyl)ammonium iodide is used instead of DODAC.

[0148] Example 7

[0149] The synthesis method and preparation conditions are the same as in Example 1, except that DODAC is replaced with bis(dodecyldimethylammonium bromide).

[0150] Comparative Example 1

[0151] Preparation of BiOCl

[0152] Simple BiOCl three-dimensional nanospheres were synthesized under conditions where the mass ratio of NH4Cl to Bi(NO3)3·5H2O was 1:3. At 25 °C, 3 g of Bi(NO3)3·5H2O and 3 mL of concentrated nitric acid were added to 40 mL of deionized water and stirred vigorously to obtain solution 1. Subsequently, 1 g of NH4Cl was dissolved in 10 mL of deionized water to obtain solution 2. Solution 2 was added to solution 1, and after stirring for 8 h, the suspension was collected, centrifuged at 5000 rpm, and washed three times with deionized water and ethanol. The mixture was then dried under vacuum at 333 K and ground to obtain BiOCl three-dimensional nanospheres. After sieving through a 200-mesh sieve, the nanospheres were stored in a glove box.

[0153] PVDF and DMF were mixed at a mass ratio of 1:10 and stirred at 500 rpm for 12 hours to obtain a PVDF solution, labeled as solution 1; LiTFSI was added to solution 1 and stirred at 500 rpm for 6 hours to obtain a solution 2, wherein the mass ratio of LiTFSI to PVDF was 1:1.

[0154] BiOCl was added to solution 2 and stirred at 400 rpm for 12 hours at 45°C to obtain solution 3, wherein the mass ratio of BiOCl to PVDF was selected as 0.1:1;

[0155] The homogenized solution 3 was subjected to ultrasonic treatment for 10 minutes each time, followed by 2 minutes of standing, for a total of 30 minutes. After ultrasonication, the ultrasonicated solution 3 was poured onto a glass plate, and the thickness of the scraper was adjusted to 300 μm for coating. After coating, the solution was allowed to stand for 2 hours, and then vacuum dried at 70°C for 24 hours to obtain a composite solid electrolyte membrane with a thickness of 50 μm.

[0156] The composite solid electrolyte membrane prepared in Comparative Example 1 was used to assemble batteries. Stainless steel sheets were used as both positive and negative electrodes to assemble SS||SS batteries; lithium metal was used as the negative electrode and stainless steel as the positive electrode to assemble Li||SS batteries; lithium metal was used as both positive and negative electrodes to prepare Li||Li symmetric batteries; and lithium metal was used as the negative electrode and NCM811 as the positive electrode to prepare Li||NCM811 full cells. All operations were performed in an argon-filled glove box.

[0157] Comparative Example 2

[0158] The synthesis method and preparation conditions are the same as in Example 1, except that the temperature for preparing solutions 1, 2, and 3, as well as the precursor solution of the composite electrolyte, is 30°C.

[0159] Comparative Example 3

[0160] The synthesis method and preparation conditions are the same as in Example 1, except that ammonium chloride is used instead of DODAC.

[0161] Comparative Example 4

[0162] The synthesis method and preparation conditions are the same as in Example 1, except that in step S2, 0.5 g of PVDF and 0.5 g of LiTFSI are added to solution 1.

[0163] Comparative Example 5

[0164] Comparative Example 5 was prepared under the same conditions as Example 1, except that in step S1, bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) and DODAC were dissolved in the same DMF to obtain solution 1, and in step S2, LiTFSI and PVDF were dissolved in solution 1 to obtain a precursor solution of the composite electrolyte. Subsequently, the precursor solution of the composite electrolyte was mechanically coated to a thickness of 400 μm. After coating, it was vacuum cured at 70 °C for 24 h to obtain a composite solid electrolyte membrane with a thickness of 70 μm.

[0165] The composite solid electrolyte membranes prepared above were assembled into batteries. Stainless steel sheets were used as both positive and negative electrodes to assemble SS||SS batteries; lithium metal was used as the negative electrode and stainless steel as the positive electrode to assemble Li||SS batteries; lithium metal was used as both positive and negative electrodes to prepare Li||Li symmetric batteries; and lithium metal was used as the negative electrode and NCM811 or LFP as the positive electrode to prepare Li||NCM811 / LFP full cells. All operations were performed in an argon-filled glove box.

[0166] Test methods

[0167] The electrochemical window of the electrolyte was determined using linear voltammetry (LSV): a Li||SS cell was used as the test cell, and the wavelength was 1 mV / s. -1 The scan rate is slowly scanned from the battery open-circuit voltage to the positive voltage to obtain the electrochemical window.

[0168] Electrochemical impedance spectroscopy (EIS) was used to determine the ionic conductivity of the electrolyte: SS||SS cells were used as the test cells for electrochemical impedance spectroscopy testing, with a frequency range of 0.1-10. -6 The frequency was Hz, and the amplitude was 10mV. After the test, the battery was disassembled to measure the thickness of the solid electrolyte, and the electrolyte ionic conductivity was calculated based on the AC impedance results.

[0169] Using a Li||Li symmetric cell as the test cell: constant current density charge-discharge test was performed on the cell. The test conditions were to apply a certain current density, charge for one hour, then discharge for one hour, and cycle the cell.

[0170] Using a Li||NCM811 full cell as the test cell: the battery was charged and discharged under a certain current density to investigate its stability, with the voltage range being 3.0V-4.3V.

[0171] The test results are shown in Table 1.

[0172] Table 1

[0173]

[0174] As shown in Table 1, Examples 1-7 exhibit better β-phase content, crystallinity, and cycle capacity retention than Comparative Examples 1-5. This indicates that the method for in-situ preparation of bismuth oxyhalide-PVDF-based composite solid electrolyte membranes can effectively utilize the characteristic that bismuth salts and organic halides containing alkyl and quaternary ammonium cations are soluble in organic solvents at 40℃-60℃ to achieve in-situ growth of bismuth oxyhalide on PVDF substrates. This results in uniform dispersion of bismuth oxyhalide in the composite solid electrolyte membrane, promotes β-phase conversion, improves battery cycle performance, and optimizes battery capacity retention.

[0175] Figure 1 The image shows the XRD pattern of BiOCl synthesized in Comparative Example 1. Figure 2 The image shows the XRD pattern of the bismuth oxyhalide-PVDF-based composite solid electrolyte membrane synthesized in Example 1. It can be observed that BiOCl was successfully synthesized in both Example 1 and Comparative Example 1. With the simultaneous addition of BiOCl, Comparative Example 1 exhibits a lower β-phase content, lower cycling performance, and a lower electrochemical window than Example 1. Figure 5 This indicates that the preparation method proposed in this scheme can effectively avoid the agglomeration problem of bismuth oxyhalides and achieve uniform distribution of bismuth oxyhalides in PVDF matrix.

[0176] Furthermore, this scheme also discusses the effect of reaction temperature on the scheme. It can be observed that when the reaction temperature of S1, S2, and S3 is 30℃ (Comparative Example 2), DODAC cannot dissolve in DMF as a solvent, so the composite solid electrolyte membrane cannot be prepared in situ. When NH4Cl is used to replace DODAC (Comparative Example 3), since NH4Cl is difficult to dissolve in DMF, the same result as in Comparative Example 2 is observed, and the preparation of the composite solid electrolyte membrane fails. Therefore, in this scheme, it is very important to ensure that the reaction temperature of S1, S2, and S3 is under heating conditions and to select an organic halide containing alkyl and quaternary ammonium cations.

[0177] In Comparative Example 4, we discussed the case where a polymer containing PVDF segments and LiTFSI were dissolved in Solution 1. It was observed that the cycling capacity retention rate of Comparative Example 4 was significantly lower than that of Example 1. This may be because the lack of a pre-formed cross-linked network structure between the organic halide containing alkyl and quaternary ammonium cations and the polymer containing PVDF segments makes it difficult for the bismuth salt to be directly anchored on the cross-linked network, which prevents the subsequent in-situ grown bismuth oxyhalide from being uniformly distributed within the composite solid electrolyte membrane.

[0178] In Comparative Example 5, we dissolved bismuth salt and organic halides containing alkyl and quaternary ammonium cations simultaneously in an organic solvent in the initial stage. This situation may lead to the immediate formation of bismuth oxyhalides, rather than the in-situ formation of bismuth oxyhalides while forming a composite solid electrolyte membrane. As a result, bismuth oxyhalides still cannot be uniformly distributed in the PVDF matrix, thus affecting the cycle performance of the battery.

[0179] To further explore the effect of temperature on this scheme, we selected different temperatures for experiments in Examples 1-2. It can be observed that when the reaction temperature in S1, S2, and S3 is 45°C, Example 1 shows a better cycle capacity retention rate. This may be because the reaction temperature of 45°C helps to further promote the dissolution of DODAC and Bi(NO3)3·5H2O in DMF, so that bismuth oxyhalide with a more uniform distribution can be generated subsequently.

[0180] In Examples 1, 3, 6, and 7, we discussed the effect of the structure of organohalides containing alkyl and quaternary ammonium cations on their performance. It can be observed that Examples 1, 6, and 7, which have symmetrical structures, exhibit better cycle capacity retention. This may be because organohalides with symmetrical structures can promote better dispersion of bismuth salts and generated bismuth oxyhalides. Therefore, Examples 1, 6, and 7 exhibit better cycle capacity retention.

[0181] To confirm the scope of application, this scheme further explored the effect of bismuth salt on its performance. It can be observed that in Examples 1, 4, and 5, the cycle capacity retention rate showed good performance, indicating that the preparation method provided by this scheme can be applied to different bismuth sources, especially oxyacid bismuth salts and organic acid bismuth salts. When oxyacid bismuth salts and organic acid bismuth salts are selected, Examples 1, 4, and 5 all showed good cycle performance.

[0182] The technical features of the embodiments described above can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions, and variations to the above embodiments within the scope of the present invention. Furthermore, without contradiction, those skilled in the art can combine and integrate different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

Claims

1. A bismuth oxyhalide-PVDF-based composite solid electrolyte membrane, characterized in that, The percentage of β phase of PVDF in the composite solid electrolyte membrane is selected from 60%-70%, and the crystallinity is 20%-25%. The general formula of bismuth oxyhalide is BiOX, where Bi is bismuth, O is oxygen, and X is a halogen element. The halogen element is selected from any one of Cl, Br, I, and F. The mass ratio of bismuth oxyhalide to the polymer containing PVDF segments is selected from (0.01-0.5):

1. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane was prepared by the following method: S1: According to the stoichiometric ratio, bismuth salt and organic halides containing alkyl and quaternary ammonium cations are dissolved in organic solvents at 40℃-60℃ to obtain solution 1 and solution 2. S2: According to the stoichiometric ratio, the polymer containing PVDF segments and lithium salt are dissolved in solution 2 at 40℃-60℃ to obtain solution 3; S3: After mixing and reacting solutions 1 and 3 at 40℃-60℃, a precursor solution of the composite electrolyte is obtained. The precursor solution of the composite electrolyte is then coated and cured to obtain a composite solid electrolyte membrane.

2. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to claim 1, characterized in that, The bismuth oxyhalide is selected from any one of BiOCl, BiOBr, BiOI, and BiOF.

3. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to claim 1, characterized in that, The bismuth oxyhalide is selected from BiOCl.

4. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to claim 1, characterized in that, In step S1, the molar ratio of bismuth salt to organohalide containing alkyl and quaternary ammonium cations is selected from 1:(2-2.5).

5. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to claim 1, characterized in that, In step S1, the mass ratio of the total mass of the bismuth salt and the organic halide containing alkyl and quaternary ammonium cations to the mass of the organic solvent is selected from (0.01-0.5):(5-20).

6. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to claim 1, characterized in that, In step S1, the bismuth salt is selected from either oxyacid bismuth salts or organic acid bismuth salts.

7. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to claim 1, characterized in that, In step S1, the organohalides containing alkyl and quaternary ammonium cations are selected from any one of organohalides containing C2-C20 alkyl and quaternary ammonium cations.

8. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to claim 7, characterized in that, In step S1, the organohalides containing C2-C20 alkyl groups and quaternary ammonium cations are selected from organohalides with structural symmetry and containing C4-C20 alkyl groups and quaternary ammonium cations.

9. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to claim 8, characterized in that, In step S1, the organohalides with structural symmetry and containing C4-C20 alkyl groups and quaternary ammonium cations are selected from ammonium halide salts with structural symmetry and containing C4-C20 alkyl groups and quaternary ammonium cations.

10. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to claim 9, characterized in that, The ammonium halide salt having a symmetrical structure and containing C4-C20 alkyl groups and quaternary ammonium cations is selected from any one of bis(octadecyl)dimethylammonium chloride, bis(dodecyl)dimethylammonium chloride, dimethylbis(tetradecyl)ammonium chloride, bis(octadecyl)dimethylammonium bromide, dimethylbis(octadecyl)iodide, tetrabutylammonium chloride, tetrapentylammonium chloride, tetrabutylammonium iodide, tetrahexylammonium iodide, and tetraheptylammonium iodide.

11. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to claim 1, characterized in that, In step S2, the mass ratio of the polymer containing PVDF segments to the lithium salt is selected from 1:(0.25-2).

12. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to claim 1, characterized in that, The mass ratio of the polymer containing PVDF segments to the organic solvent is selected from 1:(5-20).

13. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to claim 1, characterized in that, In step S2, the polymer containing PVDF segments is selected from polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, and mixtures of polyvinylidene fluoride and polyvinylidene fluoride-hexafluoropropylene.

14. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to claim 13, characterized in that, In the mixture of polyvinylidene fluoride and polyvinylidene fluoride-hexafluoropropylene, the mass ratio of polyvinylidene fluoride to polyvinylidene fluoride-hexafluoropropylene is selected from 3:

1.

15. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to claim 1, characterized in that, The lithium salt is selected from , , , , , , , , , , , , , Any one or more of them.

16. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to claim 1, characterized in that, The lithium salt is selected from LiTFSI.

17. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to claim 1, characterized in that, The organic solvent is selected from any one or more of amide solvents, pyrrolidone solvents, and ether solvents.

18. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to claim 1, characterized in that, In step S2, when the polymer containing PVDF segments and lithium salt are dissolved in solution 1 containing bismuth salt, the heating time is greater than or equal to 6 hours.

19. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to claim 1, characterized in that, In step S2, when the polymer containing PVDF segments and lithium salt are dissolved in solution 1 containing bismuth salt, the heating time is selected from 6h-10h.

20. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to claim 1, characterized in that, In step S3, the reaction time for mixing solutions 1 and 3 is selected from 22h-26h.

21. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to claim 1, characterized in that, In step S3, mechanical coating is used for coating.

22. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to claim 21, characterized in that, The mechanical coating step is as follows: pour solution 3 onto a glass plate, and then adjust the thickness of the doctor blade to 300 μm for uniform coating.

23. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to claim 1, characterized in that, The curing time is selected from 1.5h-3h.

24. The bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to claim 1, characterized in that, Step S3 also includes vacuum drying after curing, with the vacuum drying temperature selected from 60℃-80℃ and the vacuum drying time selected from 20h or more.

25. A battery, characterized in that, Includes the bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to any one of claims 1-24.

26. The battery according to claim 25, characterized in that, The battery is selected from either solid-state batteries or semi-solid-state batteries.

27. An electrochemical device, characterized in that, Includes the bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to any one of claims 1-24.

28. An electrical appliance, characterized in that, Includes the bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to any one of claims 1-24.

29. An energy storage device, characterized in that, Includes the bismuth oxyhalide-PVDF-based composite solid electrolyte membrane according to any one of claims 1-24.

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