LU600075B1

LU600075B1 - Solid electrolyte and its preparation method

Info

Publication number: LU600075B1
Application number: LU600075A
Authority: LU
Inventors: Haining Li
Original assignee: Univ Zhengzhou Light Ind
Priority date: 2024-05-16
Filing date: 2025-01-21
Publication date: 2025-07-21

Abstract

The present invention belongs to the technical field of solid electrolyte materials, and particularly relates to a solid electrolyte and its preparation method, which includes the following steps: placing inorganic ion conductor nanoparticles in a terephthalic acid solution, filtering, and immersing the solid into aZn2+ aqueous solution, followed by filtration to prepare an intermediate; placing the intermediate into an Al3+ aqueous solution, filtering, and preparing modified nanoparticles; inducing a polymerization reaction of 1-vinyl-3-ethylimidazolium tetrafluoroborate under a pressure of 7-10 GPa to obtain a polyionic liquid; dissolving the polyionic liquid, lithium salt, and the modified nanoparticles in a solvent to prepare a mixed solution, and then removing the solvent to prepare the solid electrolyte. The invention enhances the conductivity and dispersibility of the solid electrolyte by applying pressure to the ionic liquid to prepare a polyionic liquid, by compounding with inorganic ion conductor nanoparticles, and by modifying these nanoparticles, thus synergistically improving the conductivity of the solid electrolyte.

Description

SOLID ELECTROLYTE AND ITS PREPARATION METHOD 0600075

Technical Field

The present invention belongs to the technical field of solid electrolyte materials and specifically relates to a solid electrolyte and its preparation method.

Background Technology

Lithium-ion batteries are widely used in portable electronic products and electric vehicles; however, the electrolyte used in traditional lithium-ion batteries is an organic liquid, which poses safety issues such as flammability. Solid-state electrolytes can solve this problem. Currently, solid-state electrolytes are divided into inorganic solid-state electrolytes and organic solid-state electrolytes. Inorganic solid-state electrolytes have higher ionic conductivity but are more brittle, while organic solid-state electrolytes offer better toughness and are easier to process, but their ionic conductivity is relatively low.

In recent years, a novel conductive polymer material —poly(ionic liquid)s (PILs)— has attracted increasing attention from researchers. Polyionic liquids combine the advantages of ionic liquids and polymers and overcome the fluidity issue of ionic liquids, making them ideal conductive matrix materials for solid-state electrolytes.

Polyionic liquids are ionomers that are polymerized from ionic liquid monomers and contain both cationic and anionic groups in the repeating units. lonic liquids (ILs) are salts composed entirely of organic cations and inorganic or organic anions, existing in a liquid state at room temperature or near-room temperature. lonic liquids exhibit excellent chemical and thermal stability, high ionic conductivity, low flammability, a wide electrochemical window, and adjustable solvent properties, making them a new type of green solvent/soft functional material. Compared to traditional non-ionic polymers, polyionic liquids inherit these special properties of ionic liquids, such as negligible vapor pressure, thermal stability, non-flammability, ionic conductivity, electrochemical stability, and designability. Polyionic liquids not only have the advantages of ionic liquids but also generally exist in solid, liquid, or gel forms, with solid-state being the most common. Their processability, durability, and mechanical stability are superior to those of typical ionic liquids. However, the ionic conductivity LU600075 of polyionic liquids is usually at least two orders of magnitude lower than that of the corresponding ionic liquid monomers, and the conductivity of polyionic liquids still needs further improvement.

Content of the Invention

To address the above technical problems, the present invention provides a solid electrolyte and its preparation method. By applying pressure to the ionic liquid, the

C=C double bonds in the ionic liquid undergo polymerization to prepare polyionic liquids. Inorganic ion conductor nanoparticles are compounded with the polyionic liquid, and the inorganic ion conductor nanoparticles are modified to improve their conductivity and dispersibility. These various approaches synergistically enhance the ionic conductivity of the final solid electrolyte.

The present invention specifically implements this technical solution through the following methods.

The first objective of the present invention is to provide a method for preparing a solid electrolyte, comprising the following steps:

Place inorganic ion conductor nanoparticles into a terephthalic acid solution, filter, then immerse the solid into a Zn?" aqueous solution, filter, and prepare an intermediate; afterward, place the intermediate into an Al** aqueous solution, filter, and prepare modified nanoparticles;

Induce a polymerization reaction of 1-vinyl-3-ethylimidazolium tetrafluoroborate under a pressure of 7-10 GPa to obtain the polyionic liquid;

Dissolve the polyionic liquid, lithium salt, and the modified nanoparticles in a solvent to prepare a mixed solution, and then remove the solvent to prepare the solid electrolyte.

In a preferred embodiment of the present invention, during the preparation of the intermediate, the immersion process is controlled at room temperature, the concentration of the Zn?" aqueous solution is 1-2 mol/L, the ratio of the solid to the

Zn? aqueous solution is 1g:5-10mL, and the time is 1-2 hours.

In a preferred embodiment of the present invention, during the process of placing the intermediate into the Al** aqueous solution, the temperature is controlled at 80-

85°C, the concentration of the Al** aqueous solution is 1-3 mol/L, the ratio of the LU600075 intermediate to the AI** aqueous solution is 1g:3-6mL, and the time is 0.5-1 hour.

In a preferred embodiment of the present invention, during the preparation of the polyionic liquid, the pressure is maintained at 7-10 GPa for 6-8 hours.

In a preferred embodiment of the present invention, Zn?" is selected from zinc nitrate, zinc chloride, zinc sulfate, or zinc acetate, and Al** is selected from aluminum chloride or aluminum sulfate.

In a preferred embodiment of the present invention, the inorganic ion conductor nanoparticles are Lis aAlo.4Ti1.6(PO4)3 or LizLa3Zr2012.

In a preferred embodiment of the present invention, the solvent in the terephthalic acid solution is a mixture of acetonitrile and DMF in a volume ratio of 1:1- 2, the ratio of terephthalic acid to the mixed solvent is 1g:1-3mL, and the ratio of inorganic ion conductor nanoparticles to terephthalic acid solution is 1g:5-8mL.

In a preferred embodiment of the present invention, the molar ratio of polyionic liquid to lithium salt is 1:1, and the mass ratio of modified nanoparticles to polyionic liquid is 0.1-0.5:1.

In a preferred embodiment of the present invention, the solvent is acetonitrile, and the lithium salt is LiFSI or LiTFSI.

In a preferred embodiment of the present invention, the mixed solution is dropped onto a polytetrafluoroethylene disc, left to stand until the solvent completely evaporates, and then vacuum-dried at high temperature to obtain a solid electrolyte film.

The second objective of the present invention is to provide a solid electrolyte prepared by the above method. This solid electrolyte can be used in lithium-ion batteries and has high ionic conductivity.

Compared to the existing technology, the present invention offers the following beneficial effects:

To address the low ionic conductivity issue of polyionic liquid solid electrolytes, the invention proposes a new type of polyionic liquid solid electrolyte with enhanced conductivity. The specific improvements are:

Terephthalic acid is used as an organic ligand to in situ grow MOF materials on the surface of inorganic ion conductor nanoparticles with Zn?*, and AI** is then added to generate more lattice defects in the MOF material, increasing the positive charge of LU600075 the material, which facilitates the adsorption of anions in the electrolyte and enhances the migration rate of lithium ions. Additionally, the structure of the MOF material provides pathways for lithium ion migration, further improving conductivity. The modified inorganic ion conductor nanoparticles are compounded with polyionic liquids and lithium salts. The incorporation of inorganic ion conductor nanoparticles itself improves the electrolyte's conductivity, and the repulsive interactions between the positively charged nanoparticles prevent particle agglomeration, improving the interface performance between the nanoparticles and the polyionic liquid, thereby further enhancing conductivity. The polyionic liquid is prepared via pressure-induced polymerization, which improves the conductivity of the polyionic liquid itself when compared to traditional free radical polymerization methods.

Therefore, by employing pressure-induced polymerization to prepare polyionic liquids, compounding inorganic ion conductor nanoparticles, and modifying the nanoparticles to improve their conductivity and dispersibility, the present invention synergistically enhances the ionic conductivity of the final solid electrolyte.

Detailed Embodiments

To facilitate a better understanding of the technical solution of the present invention for those skilled in the art, the following specific examples and data provide a further explanation of the present invention. However, these examples are not intended to limit the scope of the present invention.

In the following examples, experimental methods and detection methods, unless otherwise specified, are conventional methods. The reagents and materials, unless otherwise stated, are commercially available.

Polyionic liquids are ideal materials for solid electrolytes due to their unique properties. This is because polyionic liquids refer to a type of ionic polymer that is synthesized by polymerizing ionic liquid monomers and contains both cationic and anionic groups on the repeating units. Polyionic liquids possess the mechanical strength, thermal stability, and processability of polymers, as well as the electrochemical properties of small-molecule ionic liquids, such as ionic conductivity and electrochemical stability. At the same time, they overcome the fluidity of ionic liquids and are commonly found in a solid state. Therefore, polyionic liquids are ideal LU600075 conductive matrix materials for solid electrolytes, avoiding the leakage and flammability issues of traditional organic liquid electrolytes, and facilitating the miniaturization, flexibility, and thin-film development of energy storage devices. 5 Currently, there are two main synthesis methods for polyionic liquids: direct synthesis and indirect synthesis. Direct synthesis involves the polymerization of unsaturated ionic liquid monomers to obtain polyionic liquids, typically using free radical polymerization. Indirect synthesis, on the other hand, involves first synthesizing a polymer and then introducing ionic liquid structures onto the molecular chain, a process known as macromolecular reaction. Free radical polymerization is more widely used. Recently, modern polymerization techniques such as Reversible Addition-

Fragmentation Chain Transfer (RAFT), Ring-Opening Metathesis Polymerization (ROMP), in situ polymerization, cyclization polymerization, and dehydrogenative coupling polymerization have also been applied to synthesize polyionic liquids.

Polyionic liquids typically have ionic conductivities at least two orders of magnitude lower than the corresponding ionic liquid monomers. Despite the development of various preparation methods for polyionic liquids, their conductivity remains limited, which hinders their application as solid electrolytes.

To address the above issues, the present invention provides a method for preparing a solid electrolyte. The method involves first inducing the polymerization of 1-vinyl-3-ethylimidazolium tetrafluoroborate under a pressure of 7-10 GPa to produce a polyionic liquid. The product obtained by pressure polymerization has a higher conductivity than that obtained by conventional synthesis methods. This is mainly because, after polymerization, the ion content is significantly reduced, and the glass transition temperature increases substantially. Polyionic liquids prepared using high- pressure methods exhibit higher conductivity than those produced by conventional free radical polymerization, indicating that pressure, as an effective structural regulation tool, can control the performance of polyionic liquids and optimize their conductivity.

In a preferred embodiment of the present invention, the pressure is maintained at 7-10 GPa for 6-8 hours to ensure that the C=CA bonds undergo sufficient breaking and re-bonding, ensuring the uniformity of the product's performance.

The present invention further composites the above polyionic liquid with LU600075 inorganic ion conductor nanoparticles. However, directly blending inorganic ion conductor nanoparticles with polyionic liquids often leads to aggregation of the nanoparticles, which affects the interface performance and results in poor conductivity.

To solve this problem, the present invention modifies the inorganic ion conductor nanoparticles by in situ growing metal-organic framework (MOF) materials on their surface. The MOF structure provides pathways for lithium ion migration, which helps to increase the electrolyte's conductivity. Additionally, the MOF material exhibits high positive charge, which facilitates the adsorption of anions in the electrolyte, further enhancing the migration of lithium ions and improving conductivity.

In a preferred embodiment of the present invention, the modification method of inorganic ion conductor nanoparticles is as follows: first, place the nanoparticles into a terephthalic acid solution, filter, then immerse the solid in a Zn?" aqueous solution, filter again to prepare an intermediate; afterward, place the intermediate into an AI** aqueous solution, filter, and prepare modified nanoparticles.

Terephthalic acid and Zn? form MOF materials, and the addition of AI** generates more lattice defects, which increases the material's positive charge.

Subsequently, the polyionic liquid, lithium salt, and modified nanoparticles are dissolved in a solvent to prepare a mixed solution, followed by solvent removal to prepare the solid electrolyte. The solid electrolyte can be prepared into a thin film by dropping the mixed solution onto a polytetrafluoroethylene (PTFE) disc, allowing the solvent to fully evaporate, and then vacuum-drying the film at high temperature.

In a preferred embodiment, the preparation of the intermediate involves controlling the immersion process at room temperature, using a Zn?* aqueous solution with a concentration of 1-2 mol/L, a solid-to-Zn?* aqueous solution ratio of 1g:5-10mL, and an immersion time of 1-2 hours. This process enables the in situ growth of MOF materials at room temperature, offering mild preparation conditions and a simple method. Zn? can be selected from zinc nitrate, zinc chloride, zinc sulfate, or zinc acetate.

In a preferred embodiment of the present invention, when placing the intermediate into the Al** aqueous solution, the temperature is controlled at 80-85°C, the concentration of the Al** solution is 1-3 mol/L, the ratio of the intermediate to the

Al? solution is 1g:3-6mL, and the time is 0.5-1 hour. The addition of AI** generates LU600075 more lattice defects, which improves the material's positive charge, enhancing the repulsive force between the inorganic ion conductor nanoparticles and preventing aggregation. Al? can be selected from aluminum chloride or aluminum sulfate.

In a preferred embodiment, during the preparation of polyionic liquids, the pressure is maintained at 7-10 GPa for 6-8 hours. The polymerization of 1-vinyl-3- ethylimidazolium tetrafluoroborate under 7-10 GPa pressure results in a polyionic liquid. The conductivity of the product prepared by pressure polymerization is higher than that obtained by conventional synthesis methods.

In a preferred embodiment, the inorganic ion conductor nanoparticles are

Lis.aAlo.4Ti1.6(PO4)3 or LizLa3Zr2012.

In a preferred embodiment, the solvent in the terephthalic acid solution is a mixture of acetonitrile and DMF in a volume ratio of 1:1-2, with the ratio of terephthalic acid to the mixed solvent being 1g:1-3mL, and the ratio of inorganic ion conductor nanoparticles to terephthalic acid solution being 1g:5-8mL. Under this solvent condition, terephthalic acid easily binds with Zn?* to form MOF materials.

In a preferred embodiment, the molar ratio of polyionic liquid to lithium salt is 1:1, and the mass ratio of modified nanoparticles to polyionic liquid is 0.1-0.5:1. The addition of inorganic ion conductor nanoparticles itself improves the conductivity of the electrolyte, and the repulsive forces between the positively charged particles prevent aggregation, improving the interface performance between the nanoparticles and the polyionic liquid, which further enhances conductivity. This ratio ensures improved conductivity in the system while keeping raw material costs reasonable.

In a preferred embodiment, the solvent is acetonitrile, and the lithium salt is LiFSI or LiTFSI. Conventional lithium salts can be used, and the raw materials are simple and readily available.

The following is a specific description of the invention by means of the following embodiments and proportions.

Example 1

A method for preparing a solid-state electrolyte, comprising the following steps:

Dissolve terephthalic acid in a solvent prepared by mixing acetonitrile and DMF in a volume ratio of 1:2. The ratio of terephthalic acid to the mixed solvent is 1g:3mL. LU600075

Place LisaAlo.aTi16(PO4)3 into the terephthalic acid solution, with a ratio of

Lis aAlo.4Ti1.6(PO4)3 to the terephthalic acid solution being 1g:7mL. Filter the mixture, then at room temperature, immerse the solid into a zinc chloride aqueous solution.

The concentration of the zinc chloride solution is 1mol/L, with the solid to Zn?" solution ratio being 1g:8mL. Leave it for 1 hour, then filter to obtain an intermediate. Afterward, place the intermediate into an aluminum chloride aqueous solution. The concentration of the aluminum chloride solution is 1mol/L, with a ratio of intermediate to Al** solution being 1g:6mL. Maintain the temperature at 80°C for 1 hour, then filter to obtain modified nanoparticles.

Induce the polymerization of 1-vinyl-3-ethylimidazolium tetrafluoroborate under 7 GPa pressure. Maintain the pressure for 6 hours to obtain the polymerized ionic liquid.

Dissolve the polymerized ionic liquid, LiFSI, and the modified nanoparticles in acetonitrile to prepare a mixed solution. Drop the mixed solution onto a polytetrafluoroethylene disk, allow the solvent to completely evaporate, then dry the film under vacuum at high temperature to obtain a solid-state electrolyte film. The molar ratio of polymerized ionic liquid to LiFSI is 1:1, and the mass ratio of modified nanoparticles to polymerized ionic liquid is 0.1:1.

Example 2

Dissolve terephthalic acid in a solvent prepared by mixing acetonitrile and DMF in a volume ratio of 1:2. The ratio of terephthalic acid to the mixed solvent is 1g:3mL.

Place LisaAlo.aTi1.6(PO4)s into the terephthalic acid solution, with a ratio of

The concentration of the zinc chloride solution is 1mol/L, with the solid to Zn?* solution ratio being 1g:8mL. Leave it for 1 hour, then filter to obtain an intermediate. Afterward, place the intermediate into an aluminum chloride aqueous solution. The concentration of the aluminum chloride solution is 1mol/L, with a ratio of intermediate to AI** solution being 1g:6mL. Maintain the temperature at 80°C for 1 hour, then filter to obtain modified nanoparticles. LU600075

Induce the polymerization of 1-vinyl-3-ethylimidazolium tetrafluoroborate under 7 GPa pressure. Maintain the pressure between 7-10 Gpa for 6 hours to obtain the polymerized ionic liquid.

Dissolve the polymerized ionic liquid, LiFSI, and the modified nanoparticles in acetonitrile to prepare a mixed solution. Drop the mixed solution onto a polytetrafluoroethylene disk, allow the solvent to completely evaporate, then dry the film under vacuum at high temperature to obtain a solid-state electrolyte film. The molar ratio of polymerized ionic liquid to LiFSI is 1:1, and the mass ratio of modified nanoparticles to polymerized ionic liquid is 0.3:1.

Example 3

Dissolve terephthalic acid in a solvent prepared by mixing acetonitrile and DMF in a volume ratio of 1:1. The ratio of terephthalic acid to the mixed solvent is 1g:3mL.

Place LisaAlo.aTi16(PO4)3 into the terephthalic acid solution, with a ratio of

The concentration of the zinc chloride solution is 1mol/L, with the solid to Zn?* solution ratio being 1g:8mL. Leave it for 1 hour, then filter to obtain an intermediate. Afterward, place the intermediate into an aluminum chloride aqueous solution. The concentration of the aluminum chloride solution is 1mol/L, with a ratio of intermediate to AI** solution being 1g:6mL. Maintain the temperature at 80°C for 1 hour, then filter to obtain modified nanoparticles.

Dissolve the polymerized ionic liquid, LiFSI, and the modified nanoparticles in acetonitrile to prepare a mixed solution. Drop the mixed solution onto a polytetrafluoroethylene disk, allow the solvent to completely evaporate, then dry the film under vacuum at high temperature to obtain a solid-state electrolyte film. The molar ratio of polymerized ionic liquid to LiFSI is 1:1, and the mass ratio of modified nanoparticles to polymerized ionic liquid is 0.5:1. LU600075

Example 4

Place LisaAlo.aTi16(PO4)3 into the terephthalic acid solution, with a ratio of

The concentration of the zinc chloride solution is 1mol/L, with the solid to Zn?" solution ratio being 1g:8mL. Leave it for 1 hour, then filter to obtain an intermediate. Afterward, place the intermediate into an aluminum chloride aqueous solution. The concentration of the aluminum chloride solution is 1mol/L, with a ratio of intermediate to AI** solution being 1g:6mL. Maintain the temperature at 80°C for 1 hour, then filter to obtain modified nanoparticles.

Induce the polymerization of 1-vinyl-3-ethylimidazolium tetrafluoroborate under 10 GPa pressure. Maintain the pressure for 6 hours to obtain the polymerized ionic liquid.

Dissolve the polymerized ionic liquid, LiFSI, and the modified nanoparticles in acetonitrile to prepare a mixed solution. Drop the mixed solution onto a polytetrafluoroethylene disk, allow the solvent to completely evaporate, then dry the film under vacuum at high temperature to obtain a solid-state electrolyte film. The molar ratio of polymerized ionic liquid to LiFSI is 1:1, and the mass ratio of modified nanoparticles to polymerized ionic liquid is 0.5:1.

Example 5

Place LisaAlo.aTi1.6(PO4)3s into the terephthalic acid solution, with a ratio of

The concentration of the zinc chloride solution is 1mol/L, with the solid to Zn?* solution LU600075 ratio being 1g:8mL. Leave it for 1 hour, then filter to obtain an intermediate. Afterward, place the intermediate into an aluminum chloride aqueous solution. The concentration of the aluminum chloride solution is 1mol/L, with a ratio of intermediate to Al* solution being 1g:6mL. Maintain the temperature at 85°C for 1 hour, then filter to obtain modified nanoparticles.

The conductivity of the solid-state electrolyte films prepared in Examples 1-5 was tested using electrochemical impedance spectroscopy, and the results are shown in

Table 1 below.

Table 1: Conductivity Data of Solid-State Electrolyte Films Prepared in Examples 1-5

Examplel 8.8x1073

Example2 9.1x1073

Example3 9.9x1073

Example4 9.2x1073

Example5 9.8x1073

From Table 1, it can be seen that the conductivity of the solid-state electrolyte films prepared in this invention ranges from (8.8-9.9)x107 S-cm*. To demonstrate the improvement in conductivity, further comparative experiments were conducted,

specifically: LU600075

Comparative Example 1

A method for preparing a solid-state electrolyte, compared to Example 3, does not immerse the intermediate in the Al** aqueous solution, comprising the following steps:

Place LisaAlo.aTi16(PO4)3 into the terephthalic acid solution, with a ratio of — LisaAloaTi1.6(PO4)3 to the terephthalic acid solution being 1g:7mL. Filter the mixture, then at room temperature, immerse the solid into a zinc chloride aqueous solution.

The concentration of the zinc chloride solution is 1mol/L, with the solid to Zn?* solution ratio being 1g:8mL. Leave it for 1 hour, then filter to obtain modified nanoparticles.

Dissolve the polymerized ionic liquid, LiFSI, and the modified nanoparticles in acetonitrile to prepare a mixed solution. Drop the mixed solution onto a PTFE disc, allow it to sit until the solvent has completely evaporated, and then dry under vacuum at high temperature to obtain the solid-state electrolyte membrane. The molar ratio of polymerized ionic liquid to LiFSl is 1:1, and the mass ratio of modified nanoparticles to polymerized ionic liquid is 0.5:1.

Comparative Example 2

A method for preparing a solid-state electrolyte, compared to Example 3, does not modify the Lis.aAlo.4Ti1.6(PO4)3, comprising the following steps:

Dissolve the polymerized ionic liquid, LiFSI, and Lis aAlo.4Ti1.6(PO4)3 nanoparticles in acetonitrile to prepare a mixed solution. Drop the mixed solution onto a PTFE disc, allow it to sit until the solvent has completely evaporated, and then dry under vacuum at high temperature to obtain the solid-state electrolyte membrane. The molar ratio LU600075 of polymerized ionic liquid to LiFSI is 1:1, and the mass ratio of Lis aAlo.aTi1.6(PO4)3 to polymerized ionic liquid is 0.5:1.

Comparative Example 3

A method for preparing a solid-state electrolyte, without adding nanoparticles, comprising the following steps:

Dissolve the polymerized ionic liquid and LiFSI in acetonitrile to prepare a mixed solution. Drop the mixed solution onto a PTFE disc, allow it to sit until the solvent has completely evaporated, and then dry under vacuum at high temperature to obtain the solid-state electrolyte membrane. The molar ratio of polymerized ionic liquid to LiFSI is 1:1.

Comparative Example 4

A method for preparing a solid-state electrolyte, compared to Example 3, uses free-radical polymerization to prepare the polymerized ionic liquid, comprising the following steps:

Place LisaAlo.aTi16(PO4)3 into the terephthalic acid solution, with a ratio of

The concentration of the zinc chloride solution is 1mol/L, with the solid to Zn2* solution ratio being 1g:8mL. Leave it for 1 hour, then filter to obtain an intermediate. Afterward, place the intermediate into an aluminum chloride aqueous solution. The concentration of the aluminum chloride solution is 1mol/L, with a ratio of intermediate to Al** solution being 1g:6mL. Maintain the temperature at 80°C for 1 hour, then filter to obtain modified nanoparticles.

Add 10.38g of 1-vinyl-3-ethylimidazolium bromide, 30mg of AIBN, and 70mL of anhydrous ethanol into a 250mL round-bottom flask. Stir the mixture under a nitrogen LU600075 atmosphere for 2 hours, then heat to 70°C and maintain for 24 hours. Wash the obtained polymerized ionic liquid (P[EVIm][Br]) with tetrahydrofuran (THF), then dry at 70°C.

In the subsequent synthesis process, dissolve 2.04g of P[EVIm][Br] in a mixed solution of 9ML deionized water and 9mL anhydrous ethanol (Solution A), and stir the solution in an ice-water bath for 30 minutes. Then, dissolve 1.10g of NaBF4 in another mixed solution of 9mL deionized water and 9mL anhydrous ethanol (Solution B) and stir in the ice-water bath for 30 minutes. Slowly add Solution B into Solution À, stir for 30 minutes, and let it sit for 1 hour. Wash the resulting light yellow solid several times with deionized water and anhydrous ethanol, and dry at 70°C for 24 hours.

Dissolve the polymerized ionic liquid, LiFSI, and modified nanoparticles in acetonitrile to prepare a mixed solution. Drop the mixed solution onto a PTFE disc, allow it to sit until the solvent has completely evaporated, and then dry under vacuum at high temperature to obtain the solid-state electrolyte membrane. The molar ratio of polymerized ionic liquid to LiFSl is 1:1, and the mass ratio of modified nanoparticles to polymerized ionic liquid is 0.5:1.

Comparative Example 5

Induce the polymerization of 1-vinyl-3-ethylimidazolium tetrafluoroborate under 7 GPa pressure. Maintain the pressure for 6 hours to obtain the polymerized ionic liquid. Dissolve the polymerized ionic liquid in acetonitrile to prepare a mixed solution.

Drop the mixed solution onto a PTFE disc, allow it to sit until the solvent has completely evaporated, and then dry under vacuum at high temperature to obtain the solid-state electrolyte membrane.

The conductivity of the solid-state electrolyte films prepared in Example 3 and

Comparative Examples 1-5 was tested, and the results are shown in Table 2 below.

Table 2: Conductivity Data of Solid-State Electrolyte Films Prepared in Example 3 and LU600075

Comparative Examples 1-5

Example 3 9.9x1073

Comparative Example 1 5.2x1073

Comparative Example 2 3.8x1073

Comparative Example 3 2.8x1073

Comparative Example 4 6.5x1073

Comparative Example 5 1.2x10-°

From Table 2, it can be observed that Comparative Example 5, where the polymerized ionic liquid is directly dissolved in the solvent to prepare the film, has a conductivity of 1.2x10° S-cm”, while the film prepared in Example 3 has a conductivity of 9.9x107 Sem”, showing a significant improvement. The analysis of the following comparative examples helps explain this improvement: Comparative Example 1: No immersion in Al** aqueous solution, resulting in a lower conductivity than Example 3.

This indicates that modification of the material with Al** can improve conductivity, as

APB* enhances the material's positive charge, which helps in the adsorption of electrolyte anions and increases lithium ion mobility, thus enhancing conductivity.

Comparative Example 2: No modification of Lis. aAlo.aTi1.6(PO4)s, but only the addition of nanoparticles, yielding a conductivity lower than that of Comparative Example 1, but higher than Comparative Example 5. This is because although nanoparticles can improve conductivity, they tend to agglomerate, which reduces their conductivity compared to Example 1. This shows that modifying the nanoparticles is necessary to achieve better conductivity. Comparative Example 3: No nanoparticles added, resulting in a lower conductivity than Comparative Example 2. Comparative Example 4: Free-radical polymerization was used to prepare the polymerized ionic liquid, which results in a lower conductivity compared to Example 3. This indicates that pressure- induced polymerization of the ionic liquid is a more effective method for improving conductivity. LU600075

Clearly, those skilled in the art can make various modifications and variations to this invention without departing from the spirit and scope of the invention. Therefore, if these modifications and variations fall within the scope of the claims and their equivalents, they are intended to be included within the scope of this invention.

Claims

CLAIMS LU600075

1. A method for preparing a solid electrolyte, characterized by comprising the following steps: Placing inorganic ion conductor nanoparticles in a terephthalic acid solution, loading terephthalic acid on the surface of the inorganic ion conductor nanoparticles, filtering, then immersing the solid into a Zn?* aqueous solution, allowing the terephthalic acid to in situ grow MOF material with Zn?* on the surface of the inorganic ion conductor nanoparticles, filtering, and preparing an intermediate; then placing the intermediate into an Al** aqueous solution, filtering, and preparing modified nanoparticles. Inducing a polymerization reaction of 1-vinyl-3-ethylimidazolium tetrafluoroborate under a pressure of 7-10 GPa to obtain a polyionic liquid. Dissolving the polyionic liquid, lithium salt, and the modified nanoparticles in a solvent to prepare a mixed solution, and then removing the solvent to prepare the solid electrolyte.

2. The preparation method according to claim 1, characterized in that, during the preparation of the intermediate, the immersion process is controlled at room temperature, the concentration of the Zn?* aqueous solution is 1-2 mol/L, the ratio of the solid to the Zn?" aqueous solution is 1g:5-10mL, and the time is 1-2 hours.

3. The preparation method according to claim 1, characterized in that, during the process of placing the intermediate into the Al** aqueous solution, the temperature is controlled at 80-85°C, the concentration of the AI** aqueous solution is 1-3 mol/L, the ratio of the intermediate to the Al** aqueous solution is 1g:3-6mL, and the time is 0.5- 1 hour.

4. The preparation method according to claim 1, characterized in that the solvent in the terephthalic acid solution is a mixture of acetonitrile and DMF in a volume ratio of 1:1-2, the amount ratio of terephthalic acid to the mixed solvent is 1g:1-3mL, and the ratio of the inorganic ion conductor nanoparticles to the terephthalic acid solution is 1g:5-8mL. LU600075

5. The preparation method according to claim 1, characterized in that during the preparation of the polyionic liquid, the pressure of 7-10 GPa is maintained for 6-8 hours.

6. The preparation method according to claim 1, characterized in that Zn?" is selected from zinc nitrate, zinc chloride, zinc sulfate, or zinc acetate, and Al** is selected from aluminum chloride or aluminum sulfate.

7. The preparation method according to claim 1, characterized in that the inorganic ion conductor nanoparticles are Lis aAlo.aTi1.6(PO4)3 or Li7LazZr2012.

8. The preparation method according to claim 1, characterized in that the molar ratio of polyionic liquid to lithium salt is 1:1, and the mass ratio of the modified nanoparticles to polyionic liquid is 0.1-0.5:1.

9. The preparation method according to claim 1, characterized in that the solvent is acetonitrile, and the lithium salt is LIFSI or LiTFSI.

10. The solid electrolyte prepared by the preparation method according to any one of claims 1-9.