Composite solid electrolyte membrane and preparation method thereof, secondary battery

Abstract

This invention provides a composite solid electrolyte membrane, its preparation method, and a secondary battery. The method for preparing the composite solid electrolyte membrane involves depositing a conductive polymer material and an organic solid electrolyte in a solvent to form a uniform gel-like film-forming substance onto the surface of an inorganic solid electrolyte, resulting in a composite electrolyte membrane with high flexibility and high conductivity. The main components of this deposited layer are the conductive polymer and the organic solid electrolyte. After film formation, a fibrous network structure is formed, which effectively improves the electron and ion transport rate. Simultaneously, the fibrous network structure enhances the processability of the electrolyte membrane. Furthermore, the introduction of the conductive polymer material effectively improves the stability of the electrolyte membrane. For example, PEDOT exhibits high stability in the oxidized state; even after being kept at 120°C for 1000 hours, its conductivity remains essentially unchanged, maintaining good conductivity and material stability even at high temperatures.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a composite solid electrolyte membrane and its preparation method, and a secondary battery. Background Technology

[0002] Traditional lithium-ion batteries use liquid electrolytes, which pose a series of safety hazards, including easy leakage, poor thermal stability, and the risk of fire and explosion due to internal short circuits. Solid-state electrolytes, compared to traditional liquid electrolytes, offer advantages such as high safety, high energy density, good cycle performance, wide operating temperature range, and convenient recycling. Solid-state electrolyte lithium-ion batteries are currently one of the hottest research topics in the energy storage field. As a core component of solid-state rechargeable batteries, solid-state electrolyte membranes have become a research focus in this field in recent years. For example, oxide solid-state electrolytes, polymer solid-state electrolytes, sulfide solid-state electrolytes, and halide solid-state electrolytes are all popular research directions. However, all of these electrolytes share the common problem of low conductivity. Therefore, a technical solution to improve the conductivity of the electrolyte is a key step in promoting the further development and application of solid-state batteries.

[0003] While single inorganic solid-state electrolyte materials possess high electronic conductivity, their synthesis process is complex, resulting in high costs and difficulties in mass production. Furthermore, their weak flexibility presents challenges in cell manufacturing, and the voids created during processing can increase surface resistance between electrodes, further diminishing the advanced nature of solid-state batteries. Organic solid-state electrolytes, developed alongside solid-state electrolytes, offer improved flexibility, but due to limitations in electron transport pathways, their conductivity remains relatively low. They also exhibit poor stability, particularly in high-temperature and other demanding operating environments, posing significant challenges.

[0004] Given the shortcomings of current single inorganic solid electrolytes and organic solid electrolytes, it is necessary to improve them. Summary of the Invention

[0005] In view of this, the present invention provides a composite solid electrolyte membrane and its preparation method, as well as a secondary battery, to solve or at least partially solve the defects existing in the prior art.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The present invention provides a composite solid electrolyte membrane, comprising an inorganic solid electrolyte and a membrane layer located on the surface of the inorganic solid electrolyte;

[0008] The membrane is composed of a conductive polymer material and an organic solid electrolyte.

[0009] Secondly, the present invention also provides a method for preparing the aforementioned composite solid electrolyte membrane, comprising the following steps:

[0010] An organic solid electrolyte and a conductive polymer material are added to a solvent to obtain an electrolyte solution.

[0011] An electrolyte solution is deposited on the surface of an inorganic solid electrolyte and the solvent is evaporated to form a film layer on the surface of the inorganic solid electrolyte, thus obtaining a composite solid electrolyte membrane.

[0012] Preferably, the inorganic solid electrolyte includes any one of oxide electrolytes, sulfide electrolytes, and halide electrolyte systems;

[0013] The organic solid electrolyte includes at least one of ethylene oxide, polyacrylonitrile, and polyvinylidene fluoride;

[0014] The conductive polymer material includes at least one of PEDOT:PSS, PEDOT:PDAS, and PEDOT:PANI;

[0015] The solvent includes at least one of DMF, NMP, acetonitrile, ethyl acetate, DMSO, DEF, THF, and water.

[0016] Preferably, the structure of the oxide electrolyte is any one of the following: NASICON structure, garnet structure, perovskite structure, and amorphous structure;

[0017] The sulfide electrolytes include LiGPS, LiSiPS, LiSnPS, Li3PS4, Li4P2S6, and Li 7-x PS 6-x X x At least one of the following, wherein 0 ≤ x ≤ 2, and X is one or more of Cl, Br, and I.

[0018] Preferably, the organic solid electrolyte and conductive polymer material are added to the solvent and stirred at a speed of 100-800 r / min, and then stirred at a speed of 8000-25000 r / min for 5-40 h, so that the conductive polymer material is drawn into fibers to obtain an electrolyte solution.

[0019] Preferably, the deposition method includes any one of sol-gel deposition, PVD deposition, CVD deposition, and electrochemical deposition.

[0020] Preferably, the deposition method is a sol-gel deposition method;

[0021] The sol-gel deposition method specifically includes:

[0022] An electrolyte solution is coated onto the surface of an inorganic solid electrolyte, and then heated at 20–300°C in an oxygen-free environment to evaporate the solvent, forming a film layer on the surface of the inorganic solid electrolyte, thus obtaining a composite solid electrolyte membrane.

[0023] Preferably, the deposition method is PVD deposition.

[0024] The PVD deposition method specifically includes:

[0025] Using an electrolyte solution as the evaporation source, the electrolyte solution is evaporated at 100–300°C and deposited on an inorganic solid electrolyte, forming a film layer on the surface of the inorganic solid electrolyte, thus obtaining a composite solid electrolyte membrane.

[0026] Preferably, the mass ratio of the organic solid electrolyte to the conductive polymer material is (0.5-0.95):(0.05-0.5);

[0027] The mass of the solvent is 2 to 10 times the sum of the masses of the organic solid electrolyte and the conductive polymer material;

[0028] The thickness of the inorganic solid electrolyte is 0.01–0.15 mm;

[0029] The thickness of the film layer is 0.01 to 0.15 mm.

[0030] Thirdly, the present invention also provides a secondary battery, comprising the composite solid electrolyte membrane described above or the composite solid electrolyte membrane prepared by the preparation method described above.

[0031] The composite solid electrolyte membrane and its preparation method, as well as the secondary battery of the present invention, have the following advantages over the prior art:

[0032] 1. The composite solid electrolyte membrane of the present invention, from the perspective of composite, retains most of the inorganic solid electrolyte as the basic part of the electrolyte membrane, and adopts organic solid electrolyte and conductive polymer material to improve the conductivity and processing performance of the electrolyte membrane.

[0033] 2. The core principle of the preparation method of the composite solid electrolyte membrane of the present invention is that a conductive polymer material and an organic solid electrolyte form a uniform gel-like film-forming substance in a solvent, which is then deposited onto the surface of an inorganic solid electrolyte to form a composite electrolyte membrane with high flexibility and high conductivity. The main components of this deposited layer are conductive polymer and organic solid electrolyte. After film formation, a fibrous network structure can be formed, which can effectively improve the electron and ion transport rate. At the same time, the fibrous network structure can improve the processing performance of the electrolyte membrane. Furthermore, the introduction of conductive polymer materials can effectively improve the stability of the electrolyte membrane. For example, PEDOT has high stability in the oxidized state; even after being kept at 120°C for 1000 hours, its conductivity remains essentially unchanged, and it can still maintain good conductivity and material stability at high temperatures. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 A photograph of the composite solid electrolyte membrane prepared according to the method in Example 1;

[0036] Figure 2 A cross-sectional SEM image of the composite solid electrolyte membrane prepared according to the method in Example 1;

[0037] Figure 3 Here is a surface SEM image of the composite solid electrolyte membrane prepared according to the method in Example 1;

[0038] Figure 4 The TGA curve is shown for the composite solid electrolyte membrane prepared according to the method in Example 1. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0041] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that 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., and single digits within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0042] This application provides a composite solid electrolyte membrane, including an inorganic solid electrolyte and a membrane layer located on the surface of the inorganic solid electrolyte;

[0043] The membrane is composed of conductive polymer materials and organic solid electrolytes.

[0044] The composite solid electrolyte membrane of the present invention, from the perspective of composite, retains most of the inorganic solid electrolyte as the basic part of the electrolyte membrane, and adopts organic solid electrolyte and conductive polymer materials to improve the conductivity and processing performance of the electrolyte membrane.

[0045] Based on the same inventive concept, the present invention also provides a method for preparing the above-mentioned composite solid electrolyte membrane, comprising the following steps:

[0046] S1. Add the organic solid electrolyte and conductive polymer material to the solvent to obtain an electrolyte solution;

[0047] S2. Deposit the electrolyte solution onto the surface of the inorganic solid electrolyte and allow the solvent to evaporate to form a film layer on the surface of the inorganic solid electrolyte, thus obtaining the composite solid electrolyte membrane.

[0048] The core principle of the preparation method of the composite solid electrolyte membrane of the present invention is that a conductive polymer material and an organic solid electrolyte form a uniform gel-like film-forming substance in a solvent, which is then deposited onto the surface of an inorganic solid electrolyte to form a composite electrolyte membrane with high flexibility and high conductivity. The main components of this deposited layer are conductive polymer and organic solid electrolyte, which can form a fibrous network structure after film formation, effectively improving the electron and ion transport rate. At the same time, the fibrous network structure can improve the processing performance of the electrolyte membrane. Furthermore, the introduction of conductive polymer materials can effectively improve the stability of the electrolyte membrane. For example, PEDOT has high stability in the oxidized state; even after being kept at 120°C for 1000 hours, its conductivity remains essentially unchanged, maintaining good conductivity and material stability even at high temperatures.

[0049] In some embodiments, an inorganic solid electrolyte is used as the first electrolyte, including but not limited to any one of oxide electrolytes, sulfide electrolytes, and halide electrolyte systems.

[0050] In some embodiments, the oxide electrolyte structure includes any one of the following: NASICON structure, garnet structure, perovskite structure, and amorphous structure.

[0051] In some embodiments, the sulfide electrolyte includes LiGPS (i.e., Li 10 GeP2S 12 At least one of the following: LiSiPS (sulfide electrolyte), LiSnPS (a ternary compound formed from lithium (Li), tin (Sn), and phosphorus (P), Li3PS4, Li4P2S6, Li 7-x PS 6-x X x At least one of the following, wherein 0 ≤ x ≤ 2, and X is one or more of Cl, Br, and I.

[0052] In some embodiments, an organic solid electrolyte is used as a second electrolyte, including but not limited to at least one of ethylene oxide (PEO), polyacrylonitrile (PAN), and polyvinylidene fluoride (PVDF);

[0053] In some embodiments, the conductive polymer material includes, but is not limited to, at least one of PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)), PEDOT:PDAS (polydiphenylamine-4-sulfonic acid dispersed poly(3,4-ethylenedioxythiophene) conductive composite), and PEDOT:PANI; the purpose is to dissolve the conductive polymer material and the organic solid electrolyte together in a solvent to obtain a mixed conductive electrolyte solution, thereby increasing the conductivity of the electrolyte membrane by 10 to 100 times compared with the conductivity of traditional electrolyte membranes, and enabling rapid electron and charge movement during battery operation.

[0054] In some embodiments, the solvent includes at least one of DMF (N,N-dimethylformamide), NMP (N-methyl-2-pyrrolidone), acetonitrile, ethyl acetate, DMSO (dimethyl sulfoxide), DEF (N,N-diethylformamide), THF (tetrahydrofuran), and water.

[0055] In some embodiments, an organic solid electrolyte and a conductive polymer material are added to a solvent and stirred at 100–800 r / min, then stirred at 8000–25000 r / min for 5–40 h, causing the conductive polymer material to be drawn into fibers, thus obtaining an electrolyte solution. Under high-speed stirring at 8000–25000 r / min, the conductive polymer material is drawn into fibers under shear force.

[0056] In some embodiments, the deposition method includes any one of sol-gel deposition, PVD deposition, CVD deposition, and electrochemical deposition.

[0057] After the solvent is evaporated, the electrolyte solution deposited on the inorganic solid electrolyte by means of solution-gel method or PVD deposition method becomes smooth and without obvious pores. This makes it possible to have no obvious boundary between the electrode and the electrolyte and no delamination phenomenon. This can effectively improve the interfacial force between the electrolyte membrane and the electrode, significantly reduce the interfacial resistance, and enhance the lithium ion transport capability at the interface.

[0058] In some embodiments, the deposition method is sol-gel deposition.

[0059] The sol-gel deposition method specifically includes:

[0060] An electrolyte solution is coated onto the surface of an inorganic solid electrolyte, and then heated at 20–300°C in an oxygen-free environment to evaporate the solvent, forming a film layer on the surface of the inorganic solid electrolyte, thus obtaining a composite solid electrolyte membrane.

[0061] In some embodiments, the deposition method is PVD deposition.

[0062] PVD deposition methods specifically include:

[0063] Using an electrolyte solution as the evaporation source, the electrolyte solution is evaporated at 100–300°C and deposited on an inorganic solid electrolyte, forming a film layer on the surface of the inorganic solid electrolyte, thus obtaining a composite solid electrolyte membrane.

[0064] In some embodiments, the mass ratio of the organic solid electrolyte to the conductive polymer material is (0.5–0.95):(0.05–0.5);

[0065] The mass of the solvent is 2 to 10 times the sum of the masses of the organic solid electrolyte and the conductive polymer material.

[0066] In some embodiments, the thickness of the inorganic solid electrolyte is 0.01–0.15 mm;

[0067] In some embodiments, the thickness of the film layer is 0.01 to 0.15 mm.

[0068] In some embodiments, the sol-gel deposition method specifically includes:

[0069] An inorganic solid electrolyte is fixed on a spin coater, and an electrolyte solution is coated onto the inorganic solid electrolyte using an electrode coating machine, so that the electrolyte solution covers the inorganic solid electrolyte. The membrane is then dried in the absence of oxygen at a temperature of 20–100°C to obtain a single-sided composite solid electrolyte membrane. The above operation is repeated to obtain a double-sided composite solid electrolyte membrane.

[0070] In some embodiments, the PVD deposition method specifically includes:

[0071] Use a vacuum pump to evacuate the inside of the evaporation equipment to a high vacuum state (10). -4 To prepare the solution, place it in an evaporation source (below Pa). Turn on the heating device and gradually increase the temperature until the solution evaporates (temperature controlled between 100 and 300°C). The evaporated gas condenses on the inorganic solid electrolyte, forming a uniform thin film. The evaporation rate is controlled by a gas flow meter to adjust the film thickness; the thickness of the dried film is 0.01–0.15 mm.

[0072] Both of the above deposition methods can form a dense and smooth film layer, which endows the composite solid electrolyte membrane with excellent conductivity and bending properties. The conductivity of the electrolyte membrane can be increased to 0.52 S / m, while improving the stability of the electrolyte membrane.

[0073] Based on the same inventive concept, the present invention also provides a secondary battery, including the composite solid electrolyte membrane described above or the composite solid electrolyte membrane prepared by the above preparation method.

[0074] The preparation method of the composite solid electrolyte membrane of this application is further illustrated below with specific embodiments. This section further illustrates the content of the present invention in conjunction with specific embodiments, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0075] Example 1

[0076] This embodiment provides a method for preparing a composite solid electrolyte membrane, including the following steps:

[0077] S1. Add the organic solid electrolyte and conductive polymer material to the solvent and stir at 400 r / min for 10 h, then stir at 15000 r / min for 25 h to draw the conductive polymer material into fibers to obtain the electrolyte solution.

[0078] The organic solid electrolyte is ethylene oxide (PEO), the conductive polymer material is PEDOT:PSS, and the solvent is DMSO (dimethyl sulfoxide).

[0079] The mass ratio of the organic solid electrolyte to the conductive polymer material is 0.95:0.05;

[0080] The mass of the solvent is five times the sum of the masses of the organic solid electrolyte and the conductive polymer material;

[0081] S2. The electrolyte solution is coated onto the inorganic solid electrolyte using an electrode coating machine, and then dried at 60°C in the absence of oxygen to obtain a membrane layer. The above operation is repeated to obtain a double-sided composite solid electrolyte membrane.

[0082] The film thickness is 0.1 mm;

[0083] The inorganic solid electrolyte is Li3PS4 with a thickness of 0.1 mm;

[0084] The preparation method of inorganic solid electrolytes includes the following steps:

[0085] Weigh 2N pure reagent Li3N, P powder, and S powder according to a stoichiometric ratio of 1:1:4, and place them in a zirconia ball mill jar equipped with an automatic pressure reducing valve. Add 10mm diameter zirconia balls, resulting in a material-to-ball ratio of 1:20. Seal the ball mill jar and fill it with inert argon gas to ensure a relative pressure >0.01MPa. Place the sealed ball mill jar in a planetary ball mill and ball mill for 10 hours at a speed of 400 r / min. After the ball mill jar cools, grind the sulfide solid electrolyte Li3PS4 produced by ball milling and pass it through a 400-mesh sieve to obtain a Li3PS4 solid electrolyte product with a particle size <40μm.

[0086] Example 2

[0087] The method for preparing the composite solid electrolyte membrane provided in this embodiment is the same as that in Embodiment 1, except that no conductive polymer material is added during preparation.

[0088] Specifically, the preparation method of the composite solid electrolyte membrane includes the following steps:

[0089] S1. Add the organic solid electrolyte to the solvent and stir at 400 r / min for 10 h, then stir at 15000 r / min for 25 h to obtain the electrolyte solution.

[0090] The organic solid electrolyte is ethylene oxide (PEO), and the solvent is DMSO (dimethyl sulfoxide).

[0091] The mass of the solvent is 5 times the mass of the organic solid electrolyte;

[0092] S2. The electrolyte solution is coated onto the inorganic solid electrolyte using an electrode coating machine, and then dried at 60°C in the absence of oxygen to obtain a membrane layer. The above operation is repeated to obtain a double-sided composite solid electrolyte membrane.

[0093] The film thickness is 0.1 mm;

[0094] The inorganic solid electrolyte is Li3PS4 with a thickness of 0.1 mm, and the preparation method is the same as in Example 1.

[0095] Example 3

[0096] The preparation method of the composite solid electrolyte membrane provided in this embodiment is the same as that in Embodiment 1, except that the mass ratio of organic solid electrolyte to conductive polymer material is 0.9:0.1, and the rest of the process is the same as in Embodiment 1.

[0097] Example 4

[0098] The preparation method of the composite solid electrolyte membrane provided in this embodiment is the same as that in Embodiment 1, except that the mass ratio of organic solid electrolyte to conductive polymer material is 0.8:0.2, and the rest of the process is the same as in Embodiment 1.

[0099] Example 5

[0100] The preparation method of the composite solid electrolyte membrane provided in this embodiment is the same as that in Embodiment 1, except that the mass ratio of organic solid electrolyte to conductive polymer material is 0.7:0.3, and the rest of the process is the same as in Embodiment 1.

[0101] Example 6

[0102] The preparation method of the composite solid electrolyte membrane provided in this embodiment is the same as that in Embodiment 1, except that the mass ratio of organic solid electrolyte to conductive polymer material is 0.6:0.4, and the rest of the process is the same as in Embodiment 1.

[0103] Example 7

[0104] The preparation method of the composite solid electrolyte membrane provided in this embodiment is the same as that in Embodiment 1, except that the mass ratio of organic solid electrolyte to conductive polymer material is 0.5:0.5, and the rest of the process is the same as in Embodiment 1.

[0105] Performance Characterization

[0106] Figure 1 This is a photograph of the composite solid electrolyte membrane prepared according to the method in Example 1.

[0107] from Figure 1 As can be seen, the addition of conductive polymer materials results in better flexibility and processing performance of the composite solid electrolyte membrane prepared by this invention.

[0108] Figure 2 This is a cross-sectional SEM image of the composite solid electrolyte membrane prepared according to the method in Example 1.

[0109] Figure 3 The image shows a surface SEM image of the composite solid electrolyte membrane prepared according to the method in Example 1.

[0110] from Figures 2-3 As can be seen, a distinct interface is formed on the surface of the inorganic solid electrolyte substrate, and the upper layer is a mixed coating of uniformly distributed and fibrous organic solid electrolyte and conductive polymer material.

[0111] Figure 4 The TGA curve is shown for the composite solid electrolyte membrane prepared according to the method in Example 1.

[0112] from Figure 4 As can be seen, the composite solid electrolyte membrane exhibits thermal weight loss at 334℃ and thermal decomposition at 350℃.

[0113] Table 1 shows the ionic conductivity and tensile strength of the composite solid electrolytes prepared in Examples 2-7.

[0114] Table 1 - Ionic conductivity and tensile strength of composite solid electrolytes in different embodiments

[0115] Example Ionic conductivity (S / m) Tensile strength (MPa) Example 1 0.33 41.9 Example 2 0.044 30.9 Example 3 0.37 45.8 Example 4 0.52 51.7 Example 5 0.52 46.0 Example 6 0.45 44.7 Example 7 0.31 43.1

[0116] As can be seen from Table 1, the ionic conductivity and tensile strength increase with the addition of conductive polymer materials, and the best performance is observed in Example 4 when the mass ratio of organic solid electrolyte to conductive polymer material is approximately 0.8:0.2.

[0117] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A composite solid-state electrolyte membrane, characterized by, This includes inorganic solid electrolytes and the film layer located on the surface of the inorganic solid electrolyte; The membrane is composed of a conductive polymer material and an organic solid electrolyte. The method for preparing the composite solid electrolyte membrane includes the following steps: An organic solid electrolyte and a conductive polymer material are added to a solvent to obtain an electrolyte solution. An electrolyte solution is deposited on the surface of an inorganic solid electrolyte and the solvent is evaporated to form a film layer on the surface of the inorganic solid electrolyte, thus obtaining a composite solid electrolyte membrane. The organic solid electrolyte is PEO; The conductive polymer material is PEDOT:PSS; The inorganic solid electrolyte is Li3PS4; Organic solid electrolyte and conductive polymer material are added to a solvent and stirred at 100~800 r / min. Then, the mixture is stirred at 8000~25000 r / min for 5~40 h to draw the conductive polymer material into fibers, thus obtaining an electrolyte solution. The mass ratio of the organic solid electrolyte to the conductive polymer material is (0.5~0.95):(0.05~0.5); The mass of the solvent is 2 to 10 times the sum of the masses of the organic solid electrolyte and the conductive polymer material; The thickness of the inorganic solid electrolyte is 0.01~0.15mm; The thickness of the film layer is 0.01~0.15mm.

2. A method for preparing a composite solid electrolyte membrane as described in claim 1, characterized in that, Includes the following steps: An organic solid electrolyte and a conductive polymer material are added to a solvent to obtain an electrolyte solution. An electrolyte solution is deposited on the surface of an inorganic solid electrolyte and the solvent is evaporated to form a film layer on the surface of the inorganic solid electrolyte, thus obtaining a composite solid electrolyte membrane. The organic solid electrolyte is ethylene oxide; The conductive polymer material is PEDOT:PSS; The inorganic solid electrolyte is Li3PS4; Organic solid electrolyte and conductive polymer material are added to a solvent and stirred at 100~800 r / min. Then, the mixture is stirred at 8000~25000 r / min for 5~40 h to draw the conductive polymer material into fibers, thus obtaining an electrolyte solution. The mass ratio of the organic solid electrolyte to the conductive polymer material is (0.5~0.95):(0.05~0.5); The mass of the solvent is 2 to 10 times the sum of the masses of the organic solid electrolyte and the conductive polymer material; The thickness of the inorganic solid electrolyte is 0.01~0.15mm; The thickness of the film layer is 0.01~0.15mm.

3. The method for preparing the composite solid electrolyte membrane as described in claim 2, characterized in that, The solvent includes at least one of DMF, NMP, acetonitrile, ethyl acetate, DMSO, DEF, THF, and water.

4. The method for preparing the composite solid electrolyte membrane as described in claim 2, characterized in that, The deposition method includes any one of sol-gel deposition, PVD deposition, CVD deposition, and electrochemical deposition.

5. The method for preparing the composite solid electrolyte membrane as described in claim 4, characterized in that, The deposition method is sol-gel deposition. The sol-gel deposition method specifically includes: An electrolyte solution is coated onto the surface of an inorganic solid electrolyte, and then heated at 20-300°C in an oxygen-free environment to evaporate the solvent, forming a film layer on the surface of the inorganic solid electrolyte, thus obtaining a composite solid electrolyte membrane.

6. The method for preparing the composite solid electrolyte membrane as described in claim 4, characterized in that, The deposition method is PVD deposition. The PVD deposition method specifically includes: Using an electrolyte solution as the evaporation source, the electrolyte solution is evaporated at 100~300℃ and deposited on an inorganic solid electrolyte, forming a film layer on the surface of the inorganic solid electrolyte, thus obtaining a composite solid electrolyte membrane.

7. A secondary battery, characterized in that, This includes the composite solid electrolyte membrane as described in claim 1 or the composite solid electrolyte membrane prepared by any of the preparation methods described in claims 2 to 6.

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