Polymer composite solid electrolyte membrane and method for preparing the same

Abstract

The application discloses a polymer composite solid-state electrolyte membrane and a preparation method thereof, and belongs to the field of batteries. The preparation method of the polymer composite solid-state electrolyte membrane comprises the following steps: step one, dispersing a polymer substrate in an organic solvent to obtain a polymer solution; the polymer solution is heated by oil bath, and a lithium salt is added; step two, dispersing an additive in an organic solvent and performing ultrasonic treatment to obtain a turbid solution; step three, dispersing an oxide electrolyte in an organic solvent to obtain an oxide electrolyte turbid solution; step four, pouring the turbid solution in step two and the oxide electrolyte turbid solution into the polymer solution to obtain an electrolyte slurry; and step five, performing film coating on the electrolyte slurry, and placing the film into a vacuum oven for drying to obtain a composite solid-state electrolyte membrane. The polymer composite solid-state electrolyte membrane comprises a polymer substrate, an oxide electrolyte, a lithium salt and an additive nano attapulgite. The application improves the conductivity of the solid-state electrolyte, and increases the mechanical strength and interface stability after film formation.

Description

Technical Field

[0001] This invention generally relates to the field of battery technology, and more specifically, to a composite electrolyte membrane based on attapulgite additives and its preparation method. Background Technology

[0002] Currently, with the development of the electric vehicle industry, lithium-ion batteries have become the core of new energy technology. Traditional liquid lithium-ion batteries currently suffer from drawbacks such as low energy density and insufficient driving range, the flammability and explosiveness of the liquid electrolyte posing safety hazards, slow charging speed with fast charging accelerating aging, temperature sensitivity requiring additional temperature control systems, high cost, and pollution risks (reliant on scarce metals and difficult to recycle). These shortcomings have driven the research and development of new technologies such as solid-state batteries.

[0003] Solid-state batteries, as the core direction of next-generation electrochemical energy storage technology, fundamentally solve the risks of flammability and explosion by replacing traditional liquid electrolytes with solid electrolytes, while also possessing advantages such as high energy density, wide temperature range adaptability, and ultra-fast charging.

[0004] Oxide electrolytes have the advantages of high stability (withstanding high voltage) and low cost, making them suitable for large-scale production and with high ionic conductivity. However, their poor solid-solid interface contact and high sintering temperature limit their applications. Polymer electrolytes can be easily formed into films, have good process compatibility and are suitable for flexible batteries, but they have low room temperature ionic conductivity, require high-temperature operating environments, and have limited room for performance improvement.

[0005] Since single electrolyte systems all have obvious technical shortcomings, improving the conductivity of solid electrolytes and enhancing the mechanical strength and interfacial stability after film formation are urgent problems that the industry needs to solve. Summary of the Invention

[0006] A primary objective of this invention is to overcome at least one of the deficiencies of the prior art and to provide a polymer composite solid electrolyte membrane and its preparation method that can improve the conductivity of solid electrolytes, enhance the mechanical strength and interfacial stability after film formation.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: According to one aspect of the present invention, a method for preparing a polymer composite solid electrolyte membrane is provided, comprising the following steps: Step 1: Disperse the polymer substrate in the organic solvent at a mass ratio of 0.05-1.0 and stir to obtain a polymer solution; heat the polymer solution in an oil bath and continue stirring; add lithium salt to the polymer solution and heat and stir in an oil bath. Step 2: Disperse the ATP particles in the organic solvent at a mass ratio of 0.05-0.3 with the additive nano-attapulgite ATP and organic solvent, and perform room temperature ultrasonic treatment to obtain an ATP turbid solution. Step 3: Disperse the oxide electrolyte in the organic solvent at a mass ratio of 0.05-0.3, and perform ultrasonic treatment at room temperature to obtain an oxide electrolyte suspension. Step 4: Pour the ATP turbid solution from Step 2 and the oxide electrolyte turbid solution from Step 3 into the polymer solution obtained in Step 1, and heat and stir in an oil bath to obtain an electrolyte slurry. Step 5: Take out the electrolyte slurry and coat it evenly on the surface of the aluminum foil using a small benchtop coating machine. Place the coated aluminum foil flat into a vacuum oven for vacuum drying to obtain a composite solid electrolyte layer.

[0008] According to one embodiment of the present invention, the polymer substrate comprises at least one selected from polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polycarbonate, polyacrylonitrile, pentaerythritol triacrylate, polymethyl methacrylate, and polyimide.

[0009] According to one embodiment of the present invention, the lithium salt in step one includes at least one of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium tetrafluoroborate, lithium di(oxalate)borate, lithium bis(fluorosulfonyl)imide, lithium di(oxalate)borate, and lithium trifluoromethanesulfonate.

[0010] According to one embodiment of the present invention, the organic solvent includes at least one selected from acetonitrile, N,N-dimethylformamide, tetrahydrofuran, succinic anionyl nitrile, acetone, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone.

[0011] According to one embodiment of the present invention, the oxide electrolyte material includes at least one of lithium lanthanum zirconium oxide, lithium titanium aluminum phosphate, lithium lanthanum titanate, and lithium aluminum titanium phosphate.

[0012] According to one embodiment of the present invention, the particle size of the oxide electrolyte material is less than 300 nm.

[0013] According to one embodiment of the present invention, the mass percentage of polymer substrate, additive ATP, oxide electrolyte and lithium salt is 15-85: 5-20: 5-30: 5-30.

[0014] According to one embodiment of the present invention, the oil bath temperature is 30-60°C, the vacuum drying temperature is 50-100°C, the thickness of the composite solid electrolyte film after formation is 10-100 micrometers, and the ambient dew point is controlled below -40°C.

[0015] According to a second aspect of the present invention, a polymer composite solid electrolyte membrane is provided, the polymer composite solid electrolyte membrane comprising a polymer substrate, an oxide electrolyte, a lithium salt, and an additive nano-attapulgite.

[0016] According to one embodiment of the present invention, the polymer composite solid electrolyte membrane is prepared according to the above-described polymer composite solid electrolyte membrane preparation method.

[0017] As can be seen from the above technical solution, the advantages and positive effects of the polymer composite solid electrolyte membrane and its preparation method of the present invention are as follows: This invention can improve the conductivity of solid electrolytes, enhance the mechanical strength and interfacial stability of the film.

[0018] This invention is the first to introduce attapulgite as an additive into an oxide polymer composite electrolyte system. The fibrous structure of attapulgite forms a fast ion transport channel, improving ion conductivity. Attapulgite also enhances the mechanical strength of the polymer matrix and inhibits lithium dendrite growth.

[0019] Nano-attapulgite (ATP,Mg5(H2O)4[Si4O) 10 [OH]2) is a hydrous magnesium aluminum silicate mineral with a rod-like crystal structure. It has needle-like and fibrous crystal structures, which can form nano-sized channels. Attapulgite nanowires can form cross-linked networks, significantly improving the mechanical strength of the electrolyte, improving the film-forming properties and flexibility of the electrolyte, and preventing lithium dendrite penetration. The nanochannel structure provides a fast migration channel for lithium ions. The surface negative charge interacts with lithium ions through Coulomb force, reducing the migration energy barrier and significantly improving the ionic conductivity of solid electrolytes. It broadens the electrochemical window to 4.7V, which can be matched with high-voltage cathode materials. It enhances thermal stability and improves the safety performance of the electrolyte.

[0020] Compared to existing technologies, the solid electrolyte slurry prepared by this invention is uniform and free of particle agglomeration. In the composition of the composite solid electrolyte, the additive attapulgite is a natural clay with a unique "sandwich" layered chain crystal structure. This structure forms its regular one-dimensional nanopores and nanorod-shaped crystals, and it contains abundant water and hydroxyl groups, with a surface rich in charge, enabling ion exchange and improving ionic conductivity. This overcomes the shortcomings of polymer electrolytes, such as low room temperature conductivity and poor mechanical properties. Detailed Implementation

[0021] The exemplary embodiments will now be described more fully. However, the exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art.

[0022] Example 1

[0023] (1) Dissolve 10g of polyethylene oxide in 60g of acetonitrile and stir with a mechanical stirrer to obtain a polymer solution; heat the polymer solution in an oil bath at 50°C and continue stirring. (2) Add 3g of lithium difluorosulfonylimide to the polymer solution described in step (1) and stir until completely dissolved; (3) Add 2g of ATP additive to 20g of acetonitrile and sonicate at room temperature for 2 hours to make ATP evenly dispersed in the solvent to obtain ATP turbidity; (4) Add 1g LATP to 10g acetonitrile and sonicate at room temperature for 2 hours to make LATP uniformly dispersed in the solvent to obtain the additive turbidity. (5) Pour the ATP turbid solution from step (3) and the LATP turbid solution from step (4) into the solution from step (2) respectively, and heat and stir in an oil bath at 50°C to obtain an electrolyte slurry; (6) Take out the electrolyte slurry described in step (5) and coat it evenly on the surface of aluminum foil on a small tabletop coating machine. Place the coated aluminum foil flat into a vacuum oven and dry it at 60°C and -0.3MPa for 12 hours. After it is completely dried, peel the coating off the aluminum foil to obtain a composite solid electrolyte membrane.

[0024] Example 2

[0025] (1) Dissolve 10g of polyethylene oxide in 120g of N-methylpyrrolidone and stir with a mechanical stirrer to obtain a polymer solution; heat the polymer solution in an oil bath at 50°C and continue stirring. (2) Add 3g of lithium difluorosulfonylimide to the polymer solution described in step (1) and stir until completely dissolved; (3) Add 3g of ATP additive to 20g of acetonitrile and sonicate at room temperature for 2 hours to make ATP evenly dispersed in the solvent to obtain ATP turbidity; (4) Add 1g LATP to 10g acetonitrile and sonicate at room temperature for 2 hours to make LATP uniformly dispersed in the solvent to obtain the additive turbidity. (5) Pour the ATP turbid solution from step (3) and the LATP turbid solution from step (4) into the solution from step (2) respectively, and heat and stir in an oil bath at 50°C to obtain an electrolyte slurry; (6) Take out the electrolyte slurry described in step (5) and coat it evenly on the surface of aluminum foil on a small tabletop coating machine. Place the coated aluminum foil flat into a vacuum oven and dry it at 70°C and -0.3MPa for 12 hours. After it is completely dried, peel the coating off the aluminum foil to obtain a composite solid electrolyte membrane.

[0026] Example 3

[0027] (1) Dissolve 10g of polyvinylidene fluoride-hexafluoropropylene in 120g of N-methylpyrrolidone and stir with a mechanical stirrer to obtain a polymer solution; heat the polymer solution in an oil bath at 50°C and continue stirring. (2) Add 5g of lithium difluorosulfonylimide to the polymer solution described in step (1) and stir until completely dissolved; (3) Add 3g of ATP additive to 20g of acetonitrile and sonicate at room temperature for 2 hours to make ATP evenly dispersed in the solvent to obtain ATP turbidity; (4) Add 1g LATP to 10g acetonitrile and sonicate at room temperature for 2 hours to make LATP uniformly dispersed in the solvent to obtain the additive turbidity. (5) Pour the ATP turbid solution from step (3) and the LATP turbid solution from step (4) into the solution from step (2) respectively, and heat and stir in an oil bath at 50°C to obtain an electrolyte slurry; (6) Take out the electrolyte slurry described in step (5) and coat it evenly on the surface of aluminum foil on a small tabletop coating machine. Place the coated aluminum foil flat into a vacuum oven and dry it at 60°C and a vacuum of -0.4MPa for 12 hours. After it is completely dried, peel the coating off the aluminum foil to obtain a composite solid electrolyte membrane.

[0028] Example 4

[0029] (1) Dissolve 10g of polyvinylidene fluoride in 100g of acetonitrile and stir with a mechanical stirrer to obtain a polymer solution; heat the polymer solution in an oil bath at 50°C and continue stirring. (2) Add 3g of lithium trifluoromethanesulfonate to the polymer solution described in step (1) and stir until completely dissolved; (3) Add 3g of ATP additive to 20g of acetonitrile and sonicate at room temperature for 2 hours to make ATP evenly dispersed in the solvent to obtain ATP turbidity; (4) Add 2g LATP to 10g acetonitrile and sonicate at room temperature for 2 hours to make LATP uniformly dispersed in the solvent to obtain the additive turbidity; (5) Pour the ATP turbid solution from step (3) and the LATP turbid solution from step (4) into the solution from step (2) respectively, and heat and stir in an oil bath at 50°C to obtain an electrolyte slurry; (6) Take out the electrolyte slurry described in step (5) and coat it evenly on the surface of aluminum foil on a small tabletop coating machine. Place the coated aluminum foil flat into a vacuum oven and dry it at 80°C and a vacuum of -0.3MPa for 12 hours. After it is completely dried, peel the coating off the aluminum foil to obtain a composite solid electrolyte membrane.

[0030] Example 5

[0031] (1) Dissolve 10g of polyethylene oxide in 80g of N,N-dimethylformamide and stir with a mechanical stirrer to obtain a polymer solution; heat the polymer solution in an oil bath at 50°C and continue stirring. (2) Add 5g of lithium trifluoromethanesulfonate to the polymer solution described in step (1) and stir until completely dissolved; (3) Add 2g of ATP additive to 20g of acetonitrile and sonicate at room temperature for 2 hours to make ATP evenly dispersed in the solvent to obtain ATP turbidity; (4) Add 2g LLZO to 10g acetonitrile and sonicate at room temperature for 2 hours to make LLZO uniformly dispersed in the solvent to obtain the additive turbid liquid; (5) Pour the ATP turbid solution from step (3) and the LLZO turbid solution from step (4) into the solution from step (2) respectively, and heat and stir in an oil bath at 50°C to obtain an electrolyte slurry; (6) Take out the electrolyte slurry described in step (5) and coat it evenly on the surface of aluminum foil on a small tabletop coating machine. Place the coated aluminum foil flat into a vacuum oven and dry it at 80°C and -0.3MPa for 8 hours. After it is completely dried, peel the coating off the aluminum foil to obtain a composite solid electrolyte membrane.

[0032] Example 6

[0033] (1) Dissolve 10g of polyethylene oxide in 100g of N,N-dimethylformamide and stir with a mechanical stirrer to obtain a polymer solution; heat the polymer solution in an oil bath at 50°C and continue stirring. (2) Add 3g of lithium trifluoromethanesulfonate to the polymer solution described in step (1) and stir until completely dissolved; (3) Add 2g of ATP additive to 20g of acetonitrile and sonicate at room temperature for 2 hours to make ATP evenly dispersed in the solvent to obtain ATP turbidity; (4) Add 2g LLZO to 20g N-methylpyrrolidone and sonicate at room temperature for 2 hours to make LLZO uniformly dispersed in the solvent to obtain an additive turbid liquid; (5) Pour the ATP turbid solution from step (3) and the LLZO turbid solution from step (4) into the solution from step (2) respectively, and heat and stir in an oil bath at 50°C to obtain an electrolyte slurry; (6) Take out the electrolyte slurry described in step (5) and coat it evenly on the surface of aluminum foil on a small tabletop coating machine. Place the coated aluminum foil flat into a vacuum oven and dry it at 60°C and -0.5MPa for 12 hours. After it is completely dried, peel the coating off the aluminum foil to obtain a composite solid electrolyte membrane.

[0034] Example 7

[0035] (1) Dissolve 10g of polyvinylidene fluoride-hexafluoropropylene in 100g of acetonitrile and stir with a mechanical stirrer to obtain a polymer solution; heat the polymer solution in an oil bath at 50°C and continue stirring. (2) Add 3g of lithium tetrafluoroborate to the polymer solution described in step (1) and stir until completely dissolved; (3) Add 3g of ATP additive to 20g of N-methylpyrrolidone and sonicate at room temperature for 2 hours to make ATP evenly dispersed in the solvent to obtain ATP turbidity; (4) Add 2g of LAGP to 20g of N-methylpyrrolidone and sonicate at room temperature for 2 hours to make LAGP uniformly dispersed in the solvent to obtain an additive turbid liquid; (5) Pour the ATP turbid solution from step (3) and the LAGP turbid solution from step (4) into the solution from step (2) respectively, and heat and stir in an oil bath at 50°C to obtain an electrolyte slurry; (6) Take out the electrolyte slurry described in step (5) and coat it evenly on the surface of aluminum foil on a small tabletop coating machine. Place the coated aluminum foil flat into a vacuum oven and dry it at 60°C and a vacuum of -0.3MPa for 15 hours. After it is completely dried, peel the coating off the aluminum foil to obtain a composite solid electrolyte membrane.

[0036] Example 8

[0037] (1) Dissolve 8g of polyethylene oxide and 2g of polyvinylidene fluoride in 100g of N,N-dimethylformamide and stir with a mechanical stirrer to obtain a polymer solution; heat the polymer solution in an oil bath at 50°C and continue stirring. (2) Add 5g of lithium tetrafluoroborate to the polymer solution described in step (1) and stir until completely dissolved; (3) Add 3g of ATP additive to 20g of N-methylpyrrolidone and sonicate at room temperature for 2 hours to make ATP evenly dispersed in the solvent to obtain ATP turbidity; (4) Add 2g LAGP to 10g N-methylpyrrolidone and sonicate at room temperature for 2 hours to uniformly disperse LAGP in the solvent to obtain an additive turbidity; (5) Pour the ATP turbid solution from step (3) and the LAGP turbid solution from step (4) into the solution from step (2) respectively, and heat and stir in an oil bath at 50°C to obtain an electrolyte slurry; (6) Take out the electrolyte slurry described in step (5) and coat it evenly on the surface of aluminum foil on a small tabletop coating machine. Place the coated aluminum foil flat into a vacuum oven and dry it at 80°C and -0.3MPa for 10 hours. After it is completely dried, peel the coating off the aluminum foil to obtain a composite solid electrolyte membrane.

[0038] Example 9

[0039] (1) Dissolve 8g of polyethylene oxide and 2g of polyvinylidene fluoride in 100g of acetonitrile and stir with a mechanical stirrer to obtain a polymer solution; heat the polymer solution in an oil bath at 50°C and continue stirring. (2) Add 3g of lithium difluorosulfonylimide to the polymer solution described in step (1) and stir until completely dissolved; (3) Add 2g of ATP additive to 20g of N,N-dimethylformamide and sonicate at room temperature for 2 hours to make ATP evenly dispersed in the solvent to obtain ATP turbidity; (4) Add 2g LLTO to 10g N,N-dimethylformamide and sonicate at room temperature for 2 hours to uniformly disperse LLTO in the solvent to obtain an additive turbid liquid; (5) Pour the ATP turbid solution from step (3) and the LLTO turbid solution from step (4) into the solution from step (2) respectively, and heat and stir in an oil bath at 50°C to obtain an electrolyte slurry; (6) Take out the electrolyte slurry described in step (5) and coat it evenly on the surface of aluminum foil on a small tabletop coating machine. Place the coated aluminum foil flat into a vacuum oven and dry it at 70°C and -0.4MPa for 12 hours. After it is completely dried, peel the coating off the aluminum foil to obtain a composite solid electrolyte membrane.

[0040] Example 10

[0041] (1) Dissolve 10g of polymethyl methacrylate in 80g of N-methylpyrrolidone and stir with a mechanical stirrer to obtain a polymer solution; heat the polymer solution in an oil bath at 50°C and continue stirring. (2) Add 3g of lithium difluorooxalate borate to the polymer solution in step (1) and stir until completely dissolved; (3) Add 3g of ATP additive to 20g of acetonitrile and sonicate at room temperature for 2 hours to make ATP evenly dispersed in the solvent to obtain ATP turbidity; (4) Add 1g LLTO to 10g acetonitrile and sonicate at room temperature for 2 hours to make LLTO uniformly dispersed in the solvent to obtain the additive turbidity; (5) Pour the ATP turbid solution from step (3) and the LLTO turbid solution from step (4) into the solution from step (2) respectively, and heat and stir in an oil bath at 50°C to obtain an electrolyte slurry; (6) Take out the electrolyte slurry described in step (5) and coat it evenly on the surface of aluminum foil on a small tabletop coating machine. Place the coated aluminum foil flat into a vacuum oven and dry it at 60°C and -0.3MPa for 12 hours. After it is completely dried, peel the coating off the aluminum foil to obtain a composite solid electrolyte membrane.

[0042] Comparative Example 1 (1) Dissolve 10g of polyethylene oxide in 80g of N-methylpyrrolidone and stir with a mechanical stirrer to obtain a polymer solution; heat the polymer solution in an oil bath at 50°C and continue stirring. (2) Add 2g of lithium difluorooxalate borate to the polymer solution in step (1) and stir until completely dissolved. Heat and stir in an oil bath at 50°C to obtain a polymer electrolyte slurry. (3) Take out the polymer electrolyte slurry described in step (2) and coat it evenly on the surface of aluminum foil on a small tabletop coating machine. Place the coated aluminum foil flat into a vacuum oven and dry it at 60°C and -0.3MPa for 12 hours. After it is completely dried, peel the coating off the aluminum foil to obtain a solid electrolyte membrane.

[0043] Comparative Example 2 (1) Dissolve 10g of polyvinyl carbonate in 100g of acetonitrile and stir with a mechanical stirrer to obtain a polymer solution; heat the polymer solution in an oil bath at 50°C and continue stirring. (2) Add 2g of lithium trifluoromethanesulfonate to the polymer solution described in step (1) and stir until completely dissolved; (3) Add 1g LLZO to 10g acetonitrile and sonicate at room temperature for 2 hours to make LLZO uniformly dispersed in the solvent to obtain the additive turbid liquid; (4) Pour the LLZO turbid liquid from step (3) into the solution from step (2) and heat and stir it in an oil bath at 45°C to obtain a composite electrolyte slurry; (5) Take out the electrolyte slurry described in step (4) and coat it evenly on the surface of aluminum foil on a small tabletop coating machine. Place the coated aluminum foil flat into a vacuum oven and dry it at 60°C and -0.3MPa for 12 hours. After it is completely dried, peel the coating off the aluminum foil to obtain a composite solid electrolyte membrane.

[0044] The electrolyte membranes obtained from the above embodiments and comparative examples were assembled and tested.

[0045] The composite polymer solid electrolyte membrane prepared above was assembled with two stainless steel electrodes (SS) to form an SS / CSEs / SS simulated cell for testing. The cell assembly process was carried out in a glove box with water and oxygen content both below 0.1 ppm. Electrochemical impedance spectroscopy (EIS) was performed at room temperature in the frequency range of 1 Hz to 1 MHz. The ionic conductivity of the prepared composite polymer solid electrolyte was calculated from the impedance data obtained from the EIS test.

[0046] Tensile strength and elongation tests: The sample (shape: 10mm wide × 100mm long) was measured using an automatic recorder on a tensile testing machine. The clamping distance between the sample was 50mm, and the test conditions were: temperature 23±2℃, suction pressure 0.30MPa, and tensile rate 20mm / min.

[0047] The test results are shown in the table below:

[0048] Table 1 As can be seen from the data in Table 1, compared with Comparative Examples 1 and 2, the electrolyte membranes obtained in Examples 1-10 have higher ionic conductivity at room temperature. The data in Table 1 also show that, compared with Comparative Examples 1 and 2, the electrolyte membranes obtained in Examples 1-10 have better tensile strength and elongation. Therefore, the composite polymer solid electrolyte membrane of the present invention not only has higher ionic conductivity at room temperature, but also exhibits higher mechanical strength and flexibility than ordinary polymer electrolyte membranes and ordinary polymer oxide composite electrolyte membranes.

[0049] Those skilled in the art should understand that the specific structures and processes shown in the above detailed embodiments are merely exemplary and not restrictive. Furthermore, those skilled in the art can combine the various technical features described above in various possible ways to form new technical solutions or make other modifications, all of which fall within the scope of this invention.

Claims

1. A method for preparing a polymer composite solid electrolyte membrane, characterized in that, Includes the following steps: Step 1: Disperse the polymer substrate in the organic solvent at a mass ratio of 0.05-1.0 and stir to obtain a polymer solution; heat the polymer solution in an oil bath and continue stirring; add lithium salt to the polymer solution and heat and stir in an oil bath. Step 2: Disperse the ATP particles in the organic solvent at a mass ratio of 0.05-0.3 with the additive nano-attapulgite ATP and organic solvent, and perform room temperature ultrasonic treatment to obtain an ATP turbid solution. Step 3: Disperse the oxide electrolyte in the organic solvent at a mass ratio of 0.05-0.3, and perform ultrasonic treatment at room temperature to obtain an oxide electrolyte suspension. Step 4: Pour the ATP turbid solution from Step 2 and the oxide electrolyte turbid solution from Step 3 into the polymer solution obtained in Step 1, and heat and stir in an oil bath to obtain an electrolyte slurry. Step 5: Take out the electrolyte slurry and coat it evenly on the surface of the aluminum foil using a small benchtop coating machine. Place the coated aluminum foil flat into a vacuum oven for vacuum drying to obtain a composite solid electrolyte layer.

2. The method for preparing a polymer composite solid electrolyte membrane according to claim 1, characterized in that: The polymer substrate includes at least one of polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polycarbonate, polyacrylonitrile, pentaerythritol triacrylate, polymethyl methacrylate, and polyimide.

3. The method for preparing a polymer composite solid electrolyte membrane according to claim 1, characterized in that: The lithium salt in step one includes at least one of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium tetrafluoroborate, lithium di(oxalate)borate, lithium bis(fluorosulfonyl)imide, lithium di(oxalate)borate, and lithium trifluoromethanesulfonate.

4. The method for preparing a polymer composite solid electrolyte membrane according to claim 1, characterized in that: The organic solvent includes at least one of acetonitrile, N,N-dimethylformamide, tetrahydrofuran, succinic anionyl nitrile, acetone, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone.

5. The method for preparing a polymer composite solid electrolyte membrane according to claim 1, characterized in that: The oxide electrolyte material includes at least one of lithium lanthanum zirconium oxide, lithium titanium aluminum phosphate, lithium lanthanum titanate, and lithium aluminum titanium phosphate.

6. The method for preparing a polymer composite solid electrolyte membrane according to claim 5, characterized in that: The particle size of the oxide electrolyte material is below 300 nm.

7. The method for preparing a polymer composite solid electrolyte membrane according to claim 1, characterized in that: The mass percentages of polymer matrix, additive ATP, oxide electrolyte and lithium salt are 15-85: 5-20: 5-30: 5-30.

8. The method for preparing a polymer composite solid electrolyte membrane according to any one of claims 1-7, characterized in that: The oil bath temperature is 30-60℃, the vacuum drying temperature is 50-100℃, the thickness of the composite solid electrolyte film is 10-100 micrometers, and the ambient dew point is controlled below -40℃.

9. A polymer composite solid electrolyte membrane, characterized in that, The polymer composite solid electrolyte membrane comprises a polymer substrate, an oxide electrolyte, a lithium salt, and an additive, nano-attapulgite.

10. The polymer composite solid electrolyte membrane according to claim 9, characterized in that, The polymer composite solid electrolyte membrane is prepared according to any one of the polymer composite solid electrolyte membrane preparation methods according to claims 1-8.

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