Solid electrolyte film and preparation method thereof

Abstract

The invention relates to a solid electrolyte film and a preparation method thereof. The method comprises the following steps: uniformly dispersing a carbon-based nano material and a conductive and proton material in a polyvinylidene fluoride (PVDF) solution, and preparing the double-ion conductor solid electrolyte film with a nano pore channel structure through an electrostatic spinning and template method. In the preparation process, the voltage, the flow speed and the receiving distance are controlled, and the uniformity and the conductivity of the pore channel structure are ensured. The obtained film achieves good balance between high ion mobility and mechanical strength, and is suitable for high-performance energy storage equipment, such as a solid-state battery. The electrolyte film shows excellent electrochemical performance and long cycle life.

Description

Technical Field

[0001] The present invention relates to the technical field of electrolyte films, and in particular to a solid electrolyte film and a preparation method thereof. Background Art

[0002] With the continuous growth of modern energy demand, energy storage technology, especially battery technology, has developed rapidly. Among the many energy storage technologies, solid-state batteries have gradually become an important development direction in the field of new energy due to their high energy density, long service life and good rate performance. Solid-state batteries are not only used in high-energy consumption equipment such as new energy vehicles, high-speed motors and submarines, but also widely used in daily equipment such as mobile communications. Compared with traditional liquid electrolyte batteries, solid-state batteries have obvious advantages in safety, operating temperature range and energy density. Especially in terms of safety, solid-state batteries have no risk of leakage of liquid electrolytes, which greatly reduces the safety hazards during use. Therefore, solid-state batteries are considered to be one of the important development directions of future energy storage technologies.

[0003] Although solid-state battery technology is constantly improving, the existing technology still has many shortcomings, which limits its further promotion and application. First of all, traditional inorganic electrolytes and polymer electrolyte materials each have their inherent defects. Although inorganic electrolytes have high ionic conductivity and excellent thermal stability, their preparation process is complicated and they are relatively brittle, making it difficult to achieve large-scale production in practical applications. Polymer electrolytes have low ionic conductivity at room temperature and are not suitable for high-voltage and high-current density environments, which limits their scope of application. In addition, the existing composite solid electrolytes still have a lot of room for optimization in improving conductivity and mechanical properties. The interfacial bonding and stability issues of composite materials, as well as the control of material uniformity during the preparation process, all have an important impact on the performance of the final product.

[0004] For example, a Chinese patent (CN114188603B) discloses a nanophase-separated solid polymer electrolyte film and its preparation method and application. The film uses a polystyrene-maleic anhydride random copolymer as a rigid main chain, and a small molecular weight polyethylene glycol segment is grafted on the main chain to obtain a polymer solid electrolyte film with a nanophase-separated structure by solution casting. This technical solution achieves the decoupling of the mechanical properties and lithium ion conductivity of the polymer solid electrolyte through the design of the polymer molecular structure, and the obtained nanophase-separated solid polymer electrolyte has excellent mechanical properties, high ion conductivity and a wide electrochemical window.

[0005] For another example, a Chinese patent (CN118117148A) discloses a method for preparing a composite solid electrolyte film. The steps include: S1, preparing graphite-like carbon nitride powder; S2, mixing graphite-like carbon nitride powder and polyvinylidene fluoride to prepare a first configuration precursor solution; S3, preparing polyvinylidene fluoride fiber membrane by electrospinning; S4, using graphite-like carbon nitride powder as a filler and preparing a second configuration precursor solution with polyethylene oxide; S5, pouring the second configuration precursor solution into the polyvinylidene fluoride fiber membrane to obtain a composite solid electrolyte film. This technical solution makes the composite solid electrolyte film have strong stability and high conductivity, which is conducive to improving the electrochemical and mechanical properties of solid-state batteries.

[0006] Existing technologies have made some progress in improving the performance of solid electrolyte films, but none of them involve the design of dual-ion conductors. The introduction of dual-ion conductor solid electrolyte films that conduct electrons and protons will effectively improve the overall performance of the battery, especially in applications that require simultaneous electron and proton conduction. This innovative dual-ion conductor system has significant technical advantages and broad application prospects, and is an important direction for the future development of solid-state battery technology. Summary of the invention

[0007] Existing technologies have made some progress in improving the performance of solid electrolyte films, but none of them involve the design of dual-ion conductors. The introduction of dual-ion conductor solid electrolyte films that conduct electricity and protons will effectively improve the overall performance of the battery, especially in applications that require simultaneous electron and proton conduction. This innovative dual-ion conductor system has significant technical advantages and broad application prospects, and is an important direction for the future development of solid-state battery technology.

[0008] The present application provides a method for preparing a solid electrolyte film, comprising the following technical steps:

[0009] Dissolve polyvinylidene fluoride (PVDF) in an appropriate amount of N,N-dimethylacetamide (DMF), stir until completely dissolved, and obtain a uniform PVDF solution; disperse the carbon-based nanomaterial in ethanol, use ultrasonic treatment to uniformly disperse, and obtain a conductive material dispersion; disperse the proton-conducting material in ethanol, and use ultrasonic treatment to uniformly disperse, and obtain a proton-conducting material dispersion; add the conductive material dispersion to the PVDF solution, stir thoroughly, and obtain a mixed precursor solution; fix the template material on the fiber receiver of the electrospinning device, and load the mixed precursor solution into the electrospinning device. In the injector of the electrospinning device, electrostatic spinning is performed by adjusting the voltage and flow rate to prepare a PVDF fiber membrane containing carbon-based nanomaterials; a certain proportion of polyethylene oxide (PEO) and a proton-conducting material are dissolved in ethanol to form a second configuration precursor solution, and the second configuration precursor solution is evenly poured on the PVDF fiber membrane and allowed to stand for a period of time to allow it to be fully infiltrated; the poured composite membrane is cured, and the cured composite film is immersed in a solvent to remove the template material, and then vacuum dried to obtain a dual ion conductor solid electrolyte film with a nanopore structure.

[0010] By adopting the above technical scheme, first, polyvinylidene fluoride (PVDF) is dissolved in N, N-dimethylacetamide (DMF) to obtain a uniform PVDF solution, which provides a good substrate for the uniform dispersion of subsequent carbon-based nanomaterials. Carbon-based nanomaterials (such as graphene or carbon nanotubes) and proton-conducting materials are uniformly dispersed in ethanol by ultrasonic treatment to form a dispersion of conductive materials and proton-conducting materials. This step ensures the full dispersion and uniformity of each functional material. Subsequently, the conductive material dispersion is mixed and stirred evenly with the PVDF solution to form a mixed precursor solution, which ensures the uniform distribution of the conductive nanomaterials in the substrate, thereby enhancing the conductivity of the final film. Then, during the electrospinning process, the mixed precursor solution is precisely controlled by a syringe and coated on a fiber receiver to form a PVDF fiber membrane. The use of template materials further ensures the formation of nanopore structures, and by adjusting the voltage and flow rate, the fiber membrane obtains a uniform and controllable pore structure during the formation process. These pores provide a path for the efficient conduction of ions, thereby optimizing the electrochemical properties of the electrolyte. Afterwards, a second configuration precursor solution of polyethylene oxide (PEO) and proton-conducting material is poured onto the fiber membrane to fully infiltrate it, ensuring the uniform distribution and full contact of the proton conductor material and improving the proton conduction efficiency. Finally, the template material is removed by curing and dissolving to form a stable nanopore structure, and the mechanical strength and stability of the film are further improved by vacuum drying. The key to the entire process is to precisely control the formation of the pores through electrospinning and template methods, so that the final film not only has excellent conductivity and proton conductivity, but also maintains high performance and stability during long-term cyclic use. This structural design and material selection enable the film to perform well in high-performance energy storage devices and can significantly improve the overall efficiency and life of the battery.

[0011] In addition, in the present application, the conductive material dispersion is first added to the polyvinylidene fluoride (PVDF) solution, which can make the conductive material fully dispersed in a higher viscosity environment and form a good bond with the matrix. This order can ensure that the conductive material is evenly distributed in the entire PVDF matrix to form a stable conductive network. After the conductive material is evenly distributed, the proton conductive material dispersion is added, which helps to avoid mutual interference between the conductive material and the proton conductive material, thereby ensuring that the proton conductive material can better fill the gaps in the conductive network. This method helps to form a dual network structure that does not interfere with each other but acts synergistically, thereby improving the overall performance of the material.

[0012] As a preferred technical solution for a method for preparing a solid electrolyte film, the carbon-based nanomaterial is graphene or carbon nanotubes, and the mass ratio of the carbon-based nanomaterial to polyvinylidene fluoride is 1 to 10:100.

[0013] By adopting the above technical solutions, the main role of graphene or carbon nanotubes is to significantly improve the comprehensive performance of solid electrolyte films by forming an efficient conductive network, improving mechanical strength, providing a high specific surface area and promoting ion migration. These characteristics make the film have a wide range of application potential in high-performance energy storage devices, especially in situations where dual conductivity (electrons and protons) functions are required, showing superior performance.

[0014] As a preferred technical solution for a method for preparing a solid electrolyte film, the proton-conducting material is zirconium phosphate or molybdenum sulfide, and the mass ratio of the proton-conducting material to polyethylene oxide is 1 to 5:100.

[0015] By adopting the above technical solution, zirconium phosphate and molybdenum sulfide are used as proton-conducting materials, which mainly improve the proton conductivity of the film, enhance the overall electrochemical performance, accelerate the proton migration rate, and provide good chemical and structural stability. These characteristics enable the film to perform well in applications that require simultaneous electron and proton conduction.

[0016] As a preferred technical solution for a method for preparing a solid electrolyte film, the voltage is controlled at 10-20 kV, the flow rate is controlled at 0.1-1 mL / h, and the receiving distance is 10-20 cm.

[0017] In this application, the control of voltage, flow rate and receiving distance not only determines the formation of fibers and the basic structure of the film, but is also closely related to the generation and optimization of the pore structure. By precisely controlling these parameters, the uniformity, size and morphology of the pore structure can be optimized, thereby providing efficient ion and electron conduction channels in the film. This optimized pore structure plays an important role in improving the performance of the electrolyte film, making the film have significant advantages in the application of high-performance energy storage devices.

[0018] As a preferred technical solution for a method for preparing a solid electrolyte film, the vacuum drying temperature is controlled at 30° C. and the drying time is 12-24 hours.

[0019] Controlling the vacuum drying temperature at 30°C and setting the drying time to 12-24 hours can effectively avoid thermal degradation of the material, ensure the complete removal of the solvent, maintain the integrity of the nanopore structure, and promote uniform drying of the film. Through this gentle and continuous drying process, the final prepared solid electrolyte film has excellent electrochemical properties and structural stability, and is suitable for application scenarios such as high-performance energy storage devices.

[0020] As a preferred technical solution for a method for preparing a solid electrolyte film, the curing time is 40° C. and the drying time is 4 to 8 hours.

[0021] The curing temperature is set at 40°C and the curing time is controlled at 4 to 8 hours. In this application, it has multiple functions such as promoting the shaping of the film structure, retaining the nanopore structure, enhancing mechanical properties, reducing internal stress, and optimizing electrochemical performance. This mild and moderate curing treatment method ensures the high quality and high performance of the solid electrolyte film, making it perform better in energy storage devices and other applications.

[0022] As a preferred technical solution for a method for preparing a solid electrolyte film, the template material is a polystyrene microsphere template, and the solvent is dichloromethane.

[0023] In this application, the use of polystyrene microspheres as template materials and dichloromethane as a solvent played a key role. The polystyrene microsphere template provides a controllable nanopore structure, while dichloromethane, as an efficient solvent, can quickly and thoroughly remove the template material, retain and optimize the pore structure, and will not damage the film matrix. This combination makes the prepared solid electrolyte film have excellent electrochemical properties and mechanical strength, meeting the application requirements of high-performance energy storage devices.

[0024] In addition, the present application discloses an electrolyte film prepared by a method for preparing a solid electrolyte film, wherein a nanopore structure is formed in the electrolyte film, and the pore size of the nanopore structure is 10nm to 100nm. In the present application, the performance of the electrolyte film is significantly improved by forming a nanopore structure with a pore size of 10nm to 100nm. The pore structure within this pore size range not only optimizes the ion and electron conduction performance of the film, but also enhances its mechanical strength, energy storage capacity and thermal management performance.

[0025] The solid electrolyte film of the present application shows significant beneficial effects through innovative material design and process optimization. First, by introducing carbon-based nanomaterials (such as graphene or carbon nanotubes) and proton-conducting materials, the film realizes the dual ion conductivity characteristics of simultaneous electrical conduction and proton conduction, greatly improving the overall performance of the battery. In addition, the nanopore structure prepared by electrospinning and template method not only effectively improves the ion mobility and electrical conductivity, but also significantly enhances the mechanical strength of the film and extends the cycle life of the battery. At the same time, the application of carbon-based nanomaterials constructs an efficient conductive network in the film, optimizes the interfacial stability of the electrolyte and the electrode, reduces the occurrence of side reactions, and thus improves the coulombic efficiency. Finally, the optimized pore size distribution and material ratio enable the electrolyte film to still maintain excellent electrochemical properties under high current density conditions, and is suitable for various high-performance energy storage devices, with broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0027] Figure 1 The pore size distribution diagram of the pores in the electrolyte membranes prepared in Examples 1 to 3;

[0028] Figure 2 It is a data diagram of Example 1 and Comparative Example 1;

[0029] Figure 3 It is a data graph of Example 2 and Comparative Example 2. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0031] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0032] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0033] Example 1

[0034] A method for preparing a solid electrolyte film comprises the following technical steps:

[0035] S1. Dissolve polyvinylidene fluoride (PVDF) in an appropriate amount of N,N-dimethylacetamide (DMF) and stir until completely dissolved to obtain a uniform PVDF solution;

[0036] S2. Dispersing graphene in ethanol and using ultrasonic treatment to uniformly disperse the graphene to obtain a conductive material dispersion; wherein the mass ratio of graphene to N,N-dimethylacetamide in step S1 is 1:100;

[0037] S3. Dispersing zirconium phosphate in ethanol and uniformly dispersing it by ultrasonic treatment to obtain a dispersion of a proton-conducting material;

[0038] S4. Add the conductive material dispersion to the PVDF solution and stir well to obtain a mixed precursor solution;

[0039] S5. Fix the polystyrene microsphere template on the fiber receiver of the electrospinning device, and load the mixed precursor solution into the syringe of the electrospinning device, and perform electrospinning by adjusting the voltage and flow rate to prepare a PVDF fiber membrane containing carbon-based nanomaterials; wherein the voltage is controlled at 20 kV, the flow rate is controlled at 0.5 mL / h, and the receiving distance is 20 cm;

[0040] S6. A certain proportion of polyethylene oxide (PEO) and a proton-conducting material are dissolved in ethanol to form a second configuration precursor solution, and the second configuration precursor solution is evenly poured on the PVDF fiber membrane and allowed to stand for a period of time to allow it to be fully infiltrated; wherein the mass ratio of the proton-conducting material to the polyethylene oxide is 5:100;

[0041] S7. The cast composite film is cured, and the cured composite film is immersed in a solvent to remove the template material, and then vacuum dried to obtain a dual ion conductor solid electrolyte film with a nanopore structure, wherein the curing time is 40°C, the drying time is 8 hours, the vacuum drying temperature is controlled at 30°C, and the drying time is 12 hours.

[0042] Example 2

[0043] A method for preparing a solid electrolyte film comprises the following technical steps:

[0044] S1. Dissolve polyvinylidene fluoride (PVDF) in an appropriate amount of N,N-dimethylacetamide (DMF) and stir until completely dissolved to obtain a uniform PVDF solution;

[0045] S2. dispersing the carbon nanotubes in ethanol and treating them with ultrasound until they are uniformly dispersed to obtain a conductive material dispersion; wherein the mass ratio of graphene to N,N-dimethylacetamide in step S1 is 10:100;

[0046] S3. dispersing molybdenum sulfide in ethanol and uniformly dispersing the molybdenum sulfide in ethanol by ultrasonic treatment to obtain a dispersion of a proton-conducting material;

[0047] S4. Add the conductive material dispersion to the PVDF solution and stir well to obtain a mixed precursor solution;

[0048] S5. Fix the polystyrene microsphere template on the fiber receiver of the electrospinning device, and load the mixed precursor solution into the syringe of the electrospinning device. Perform electrospinning by adjusting the voltage and flow rate to prepare a PVDF fiber membrane containing carbon-based nanomaterials; wherein the voltage is controlled at 10 kV, the flow rate is controlled at 1 mL / h, and the receiving distance is 10 cm

[0049] S6. A certain proportion of polyethylene oxide (PEO) and a proton-conducting material are dissolved in ethanol to form a second configuration precursor solution, and the second configuration precursor solution is evenly poured on the PVDF fiber membrane and allowed to stand for a period of time to allow it to be fully infiltrated; wherein the mass ratio of the proton-conducting material to the polyethylene oxide is 1:100;

[0050] S7. The cast composite film is cured, and the cured composite film is immersed in a solvent to remove the template material, and then vacuum dried to obtain a dual ion conductor solid electrolyte film with a nanopore structure, wherein the curing time is 40°C, the drying time is 8 hours, the vacuum drying temperature is controlled at 30°C, and the drying time is 24 hours.

[0051] Example 3

[0052] A method for preparing a solid electrolyte film comprises the following technical steps:

[0053] S1. Dissolve polyvinylidene fluoride (PVDF) in an appropriate amount of N,N-dimethylacetamide (DMF) and stir until completely dissolved to obtain a uniform PVDF solution;

[0054] S2. Dispersing graphene in ethanol and using ultrasonic treatment to uniformly disperse the graphene to obtain a conductive material dispersion; wherein the mass ratio of graphene to N,N-dimethylacetamide in step S1 is 5:100;

[0055] S3. dispersing molybdenum sulfide in ethanol and uniformly dispersing the molybdenum sulfide in ethanol by ultrasonic treatment to obtain a dispersion of a proton-conducting material;

[0056] S4. Add the conductive material dispersion to the PVDF solution and stir well to obtain a mixed precursor solution;

[0057] S5. Fix the polystyrene microsphere template on the fiber receiver of the electrospinning device, and load the mixed precursor solution into the syringe of the electrospinning device, and perform electrospinning by adjusting the voltage and flow rate to prepare a PVDF fiber membrane containing carbon-based nanomaterials; wherein the voltage is controlled at 15 kV, the flow rate is controlled at 0.1 mL / h, and the receiving distance is 15 cm;

[0058] S6. A certain proportion of polyethylene oxide (PEO) and a proton-conducting material are dissolved in ethanol to form a second configuration precursor solution, and the second configuration precursor solution is evenly poured on the PVDF fiber membrane and allowed to stand for a period of time to allow it to be fully infiltrated; wherein the mass ratio of the proton-conducting material to the polyethylene oxide is 3:100;

[0059] S7. The cast composite film is cured, and the cured composite film is immersed in a solvent to remove the template material, and then vacuum dried to obtain a dual ion conductor solid electrolyte film with a nanopore structure, wherein the curing time is 40°C, the drying time is 8 hours, the vacuum drying temperature is controlled at 30°C, and the drying time is 24 hours.

[0060] Comparative Example 1

[0061] The difference between this comparative example and Example 1 is that in step S5, the polystyrene microsphere template is not fixed on the fiber receiver of the electrospinning device, and the dissolving agent in the subsequent step S7 is not required to remove the template.

[0062] Comparative Example 2

[0063] The difference between this comparative example and Example 2 is that step 3 is removed, and in step S6, polyethylene oxide (PEO) is dissolved in ethanol to form a second configuration precursor solution, and the second configuration precursor solution is evenly poured on the PVDF fiber membrane and left to stand for a period of time to allow it to be fully infiltrated.

[0064] Application Example 1

[0065] Battery assembly steps: LiCoO2 is selected as the positive electrode material and graphite is used as the negative electrode material. The solid electrolyte material prepared in Examples 1 to 3 and Comparative Examples 1 and 2 of the present application is placed between the positive and negative electrodes as the electrolyte membrane of the battery. The specific assembly process is carried out in a glove box to prevent the influence of air and moisture on the battery materials. The positive electrode, electrolyte material and negative electrode are assembled into a battery using a pressing or winding process.

[0066] Performance Testing

[0067] Pore ​​size analysis of electrolyte materials: The nitrogen adsorption-desorption method (BET / BJH) calculates the parameters of the pore structure by measuring the amount of nitrogen adsorbed by the material at different pressures.

[0068] Constant current charge and discharge test: Connect the assembled battery to the battery tester, perform multiple charge and discharge cycles on the battery at a set current density (0.1C to 2C), and record the battery's voltage, current, and time data.

[0069] Combining Examples 1 to 3 and Figure 1It can be seen that the pore size distribution of Example 1 is mainly concentrated in the range of 30 to 70 nanometers, the pore size distribution of Example 2 is mainly concentrated in the range of 10 to 50 nanometers, and the pore size distribution of Example 3 ranges from 40 to 100 nanometers. Nanopores have a key impact on the performance of electrolytes. First, nanoscale pores can significantly increase the specific surface area of ​​the electrolyte, which helps to improve the mobility and conductivity of ions. Nanopores provide a shorter ion conduction path, allowing ions to pass through the electrolyte more quickly, thereby increasing the power density of the battery. In addition, the presence of nanopores can form a larger interface contact area between the electrolyte and the electrode, enhance the interface compatibility, effectively reduce the interface impedance, and improve the electrochemical performance of the battery.

[0070] Combined with Example 1, Comparative Example 1 and Figure 2 It can be seen that during 8000 cycles, the capacity retention rate of Example 1 remained at a high level, always above 99%, and the downward trend was relatively slow, which shows that the electrolyte material in Example 1 has good stability and durability during long-term cycles; in contrast, the capacity retention rate of Comparative Example 1 decreased rapidly, gradually decreasing from the initial nearly 100% to about 97%, and the downward trend was obvious, which shows that the electrolyte material in Comparative Example 1 has a more significant performance degradation during long-term cycles; the coulombic efficiency of Example 1 was maintained at about 98% during the entire cycle, showing extremely high energy efficiency, which shows that the electrolyte material in Example 1 can effectively inhibit the occurrence of side reactions, reduce energy loss, and ensure efficient operation of the battery; the coulombic efficiency of Comparative Example 1 The efficiency is relatively low, maintained at about 97%. The lower coulombic efficiency indicates that in Comparative Example 1, the electrochemical stability of the electrolyte material is relatively poor, and more side reactions may have occurred, resulting in increased energy loss; the pore structure provides an efficient ion migration channel, so that the ions in the electrolyte can move quickly and smoothly. This efficient ion migration helps to reduce the internal resistance of the electrolyte and reduce energy loss during charging and discharging, thereby improving the coulombic efficiency; the pore structure not only optimizes ion migration, but also may form a more stable interface contact between the electrolyte and the electrode. The stable interface reduces the side reactions between the electrolyte and the electrode, such as decomposition of the electrolyte or corrosion of the electrode material. Reducing these side reactions can greatly improve the coulombic efficiency and maintain a high capacity retention rate over a long period of cycling.

[0071] Combined with Example 2, Comparative Example 2 and Figure 3It can be seen that during 8000 cycles, the capacity retention rate of Example 2 remains at a high level, always above 99%, and the downward trend is relatively slow, which indicates that the electrolyte material in Example 2 has good stability and durability during long-term cycles; in contrast, the capacity retention rate of Comparative Example 2 decreases rapidly, gradually decreasing from the initial nearly 100% to about 97%, and the downward trend is obvious, which indicates that the electrolyte material in Comparative Example 2 has a more significant performance degradation during long-term cycles; the coulombic efficiency of Example 2 remains at about 98.5% during the entire cycle, showing extremely high energy efficiency, which indicates that the electrolyte material in Example 2 can effectively inhibit the occurrence of side reactions, reduce energy loss, and ensure efficient operation of the battery; the coulombic efficiency of Comparative Example 2 is relatively low, remaining at about 96%, and the lower coulombic efficiency indicates that in the comparative example 2, the electrolyte material in Example 2 has good stability and durability during long-term cycles. In ratio 2, the electrochemical stability of the electrolyte material is relatively poor, and more side reactions may occur, resulting in increased energy loss; proton-conducting materials (such as zirconium phosphate or molybdenum sulfide) have good proton conductivity, and they can provide efficient proton conduction channels in the electrolyte film. This efficient proton conductivity forms a synergistic effect with the electronic conductivity in the electrolyte, so that the battery can efficiently conduct protons and electrons during the charge and discharge process, reducing the internal resistance, thereby improving the coulomb efficiency. In addition, the efficient proton conductivity can also ensure that the electrolyte maintains a high ion mobility and reduces the capacity decay during long-term cyclic use; proton materials can not only effectively conduct protons, but also form a stable interface layer between the electrolyte and the electrode, inhibiting the occurrence of side reactions. The stable interface layer reduces the corrosion of the electrode material and the decomposition of the electrolyte, thereby improving the coulomb efficiency. This stability of the proton-conducting material is particularly important in long-term use. It can prevent the rapid degradation of the electrolyte film, so that the capacity retention rate can still be maintained at a high level after 8,000 cycles.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a solid electrolyte film, characterized in that: The technical steps include: Dissolve polyvinylidene fluoride (PVDF) in an appropriate amount of N,N-dimethylacetamide (DMF) and stir until completely dissolved to obtain a uniform PVDF solution; The carbon-based nanomaterial is dispersed in ethanol and treated with ultrasound until it is uniformly dispersed to obtain a conductive material dispersion; Dispersing the proton-conducting material in ethanol and uniformly dispersing the material by ultrasonic treatment to obtain a proton-conducting material dispersion; Add the conductive material dispersion into the PVDF solution and stir thoroughly to obtain a mixed precursor solution; The template material is fixed on a fiber receiver of an electrospinning device, and the mixed precursor solution is loaded into a syringe of the electrospinning device, and the voltage and flow rate are adjusted to perform electrospinning to prepare a PVDF fiber membrane containing carbon-based nanomaterials; A certain proportion of polyethylene oxide (PEO) and a proton-conducting material are dissolved in ethanol to form a second configuration precursor solution, and the second configuration precursor solution is evenly poured on the PVDF fiber membrane and allowed to stand for a period of time to allow it to be fully infiltrated; The cast composite film is cured, immersed in a solvent to remove the template material, and then vacuum dried to obtain a dual ion conductor solid electrolyte film with a nanopore structure.

2. The method for preparing a solid electrolyte film according to claim 1, characterized in that: The carbon-based nanomaterial is graphene or carbon nanotube, and the mass ratio of the carbon-based nanomaterial to polyvinylidene fluoride is 1 to 10:

100.

3. The method for preparing a solid electrolyte film according to claim 1, characterized in that: The proton-conducting material is zirconium phosphate or molybdenum sulfide, and the mass ratio of the proton-conducting material to polyethylene oxide is 1 to 5:

100.

4. The method for preparing a solid electrolyte film according to claim 1, characterized in that: The voltage was controlled at 10-20 kV, the flow rate was controlled at 0.1-1 mL / h, and the receiving distance was 10-20 cm.

5. The method for preparing a solid electrolyte film according to claim 1, characterized in that: The vacuum drying temperature is controlled at 30° C. and the drying time is 12-24 hours.

6. The method for preparing a solid electrolyte film according to claim 1, characterized in that: The curing time is 40°C and the drying time is 8 hours.

7. The method for preparing a solid electrolyte film according to claim 1, characterized in that: The template material is a polystyrene microsphere template, and the solvent is dichloromethane.

8. An electrolyte membrane prepared by the method for preparing a solid electrolyte membrane according to any one of claims 1 to 7, characterized in that: A nanopore structure is formed in the electrolyte film, and the pore diameter of the nanopore structure is 10nm to 100nm.

Images