Solid-state electrolyte, solid-state battery, and preparation method

Abstract

The application discloses a kind of solid electrolyte, solid battery and preparation method, belong to battery material technical field, by mass fraction, include following component: 5-6 parts electrically-conductive reinforced nylon powder, 5-8 parts electrically-conductive carbon black, 5-6 parts sodium dodecyl benzene sulfonate, 60-80 parts polyvinylidene fluoride and 500-600 parts N-methyl-2-pyrrolidone;Electrically-conductive carbon black, sodium dodecyl benzene sulfonate and polyvinylidene fluoride, N-methyl-2-pyrrolidone and electrically-conductive reinforced nylon powder are mixed after stirring and coated on glass plate, and solid electrolyte is obtained by drying;Fe-MOF with porous structure is synthesized on the surface of electrically-conductive carbon nanotube in the application, the adsorption capacity of electrically-conductive ionic liquid is improved, the agglomeration of MOF composite carbon nanotube loaded is reduced by the hydrogen bond effect and the network structure is formed by the composite of nylon powder, and the conductivity and mechanical properties are enhanced.

Description

Technical Field

[0001] This invention belongs to the field of battery materials technology, specifically relating to a solid electrolyte, a solid battery, and a preparation method thereof. Background Technology

[0002] Solid-state batteries are advantageous for storage, offer high safety, are environmentally friendly, and have high energy efficiency, making them a major research direction in battery technology. Unlike liquid electrolytes commonly used in batteries and energy storage devices, solid-state batteries have solid electrodes and use ion-conducting solid electrolytes. There are various types of solid electrolytes, such as oxides, sulfides, polymers, and combinations thereof. Oxides and sulfides have high mechanical strength and good ionic conductivity; however, oxide solid electrolytes have poor interfacial contact, which easily leads to a continuous increase in interfacial impedance during cycling, resulting in rapid battery life degradation. Sulfide solid electrolytes are sensitive to water and oxygen, are flammable, and have difficult manufacturing processes. Polymer solid electrolytes have better interfacial impedance than the other two types of solid electrolytes due to the viscoelasticity of polymers; however, polymers have lower ionic conductivity and poorer mechanical strength.

[0003] Chinese invention patent application CN112086678A discloses a solid electrolyte and its preparation method, as well as a solid-state battery, which utilizes a ceramic-based ion conductor, a polymer ion conductor, and a lithium salt; the polymer ion conductor comprises a base polymer and dopants to prepare the solid electrolyte. However, the ceramic-based electrolyte has poor conductivity, and the conductive active material is prone to migration and loss during cycling, affecting the lifespan of the solid-state battery. Summary of the Invention

[0004] The purpose of this invention is to solve the problem of how to improve the conductivity and mechanical strength of polymer solid electrolytes, and to provide a solid electrolyte, a solid battery and a preparation method thereof.

[0005] This invention enhances the adsorption capacity of conductive ionic liquids by synthesizing Fe-MOF with a porous structure on the surface of conductive carbon nanotubes. By combining the loaded MOF composite carbon nanotubes with nylon powder through hydrogen bonding, the aggregation of the loaded MOF composite carbon nanotubes is reduced and a network structure is formed, thereby enhancing the conductivity and mechanical properties of the solid electrolyte.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A solid electrolyte, comprising, by mass parts, the following components:

[0008] 5-6 parts conductive reinforced nylon powder, 5-8 parts conductive carbon black, 5-6 parts sodium dodecylbenzenesulfonate, 60-80 parts polyvinylidene fluoride and 500-600 parts N-methyl-2-pyrrolidone.

[0009] Furthermore, the conductive reinforced nylon powder is prepared by the following steps:

[0010] Fe-MOF was generated in situ on the surface of carboxylated multi-walled carbon nanotubes to obtain MOF composite carbon nanotubes. Ionic liquid was loaded into the MOF composite carbon nanotubes to obtain loaded MOF composite carbon nanotubes. Nylon powder was ultrasonically dispersed in sodium hydroxide solution, and after stirring, the loaded MOF composite carbon nanotubes were added. The mixture was ultrasonically treated for 1-2 hours, and the precipitate was collected by centrifugation, washed, and vacuum dried to obtain conductive reinforced nylon powder.

[0011] Furthermore, the ratio of nylon powder, sodium hydroxide solution, and supported MOF composite carbon nanotubes is 8-10g: 100-150mL: 3-4g; the sodium hydroxide solution is prepared by mixing sodium hydroxide, dicyandiamine, and deionized water in a ratio of 2-3g: 0.8-1g: 50-100mL.

[0012] Furthermore, the MOF-supported composite carbon nanotubes are prepared by the following steps:

[0013] In a reaction vessel, ionic liquid and ethanol are mixed, MOF composite carbon nanotubes are added, and the mixture is stirred for 1-2 hours. Ethanol is removed by rotary evaporation, and the mixture is dried under vacuum to obtain supported MOF composite carbon nanotubes.

[0014] Furthermore, the ratio of ionic liquid, ethanol and MOF composite carbon nanotubes is 0.8-1g: 20-30mL: 3-4g.

[0015] Furthermore, ionic liquids are prepared by the following steps:

[0016] Diethylmethylamine and 1-bromo-2-methoxyethane were dissolved in acetonitrile in a reaction vessel and reacted at 50-60℃ for 10-12 h under nitrogen protection. The precipitate was obtained by leaching with ethanol, and after vacuum drying, it was dissolved in a 1M aqueous solution of lithium bis(trifluoromethane)sulfonylimide. The reaction was stirred for 1-2 h, and the precipitate was extracted with dichloromethane. The precipitate was filtered, washed, and then vacuum dried to obtain an ionic liquid.

[0017] Furthermore, the ratio of diethylmethylamine, 1-bromo-2-methoxyethane, and acetonitrile is 0.8-1 g: 1.5-2 g: 20-30 mL.

[0018] Furthermore, the MOF composite carbon nanotubes are prepared by the following steps:

[0019] Carboxylated multi-walled carbon nanotubes and 2-aminoterephthalic acid were added to DMF in a reaction vessel and sonicated for 30-40 min. Then, ferric chloride hexahydrate was added, and the mixture was heated to 140-150℃ and reacted for 20-24 h. After cooling, the precipitate was collected by centrifugation, washed, and vacuum dried to obtain MOF composite carbon nanotubes.

[0020] Furthermore, the ratio of carboxylated multi-walled carbon nanotubes, 2-aminoterephthalic acid, DMF, and ferric chloride hexahydrate is 2-3g: 2-4g: 80-100mL: 8-10g.

[0021] Furthermore, the solid electrolyte is prepared by the following steps:

[0022] Conductive carbon black, sodium dodecylbenzenesulfonate, and polyvinylidene fluoride are ultrasonically dispersed in N-methyl-2-pyrrolidone in a reaction vessel. Conductive reinforced nylon powder is added, and the mixture is stirred for 10-12 hours. The solution is then coated onto a glass plate with a thickness of 200-250 μm and dried in an oven at 90-100 °C for 10-12 hours to obtain a solid electrolyte.

[0023] A method for preparing a solid-state battery includes the following steps:

[0024] A mixed solvent was prepared by mixing N-methylpyrrolidone and dimethylacetamide. Activated carbon and conductive carbon black were added to the mixed solvent and stirred and ground to obtain a slurry. The slurry was sprayed and dried, and then compacted and sliced ​​to obtain an electrode sheet. The electrode sheet, solid electrolyte and lithium sheet were assembled in sequence and then encapsulated in a shell to obtain a solid-state battery.

[0025] The beneficial effects of this invention are:

[0026] 1. This invention enhances the adsorption capacity of conductive ionic liquids and improves the conductivity of solid electrolytes by synthesizing Fe-MOF with a porous structure on the surface of conductive carbon nanotubes. By combining the loaded MOF composite carbon nanotubes with nylon powder through hydrogen bonding, the aggregation of the loaded MOF composite carbon nanotubes is reduced, and the nylon powder is used to form a network structure, further enhancing the conductivity of the solid electrolyte. At the same time, the conductive network formed by the nylon powder also enhances the mechanical properties of the solid electrolyte, resulting in a solid electrolyte with good conductivity and mechanical properties.

[0027] 2. The solid electrolyte obtained by the present invention involves reacting the amino groups in 2-aminoterephthalic acid with the carboxyl groups on the surface of carboxylated multi-walled carbon nanotubes, grafting 2-aminoterephthalic acid onto the surface of the carboxylated multi-walled carbon nanotubes, thereby generating Fe-MOF with a porous structure on the surface of the carboxylated multi-walled carbon nanotubes. The surface of the MOF composite carbon nanotubes contains the amino groups of Fe-MOF, which form hydrogen bonds with the amino groups formed by the hydrolysis of nylon powder and diamine, promoting the uniform composite of the loaded MOF composite carbon nanotubes and nylon powder, resulting in conductive nylon powder. The nylon powder has a certain mechanical strength, and the interlaced network of the nylon powder is conducive to the formation of a conductive network, improving the mechanical strength and conductivity of the solid electrolyte. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments in the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1: A solid electrolyte, prepared by the following steps:

[0030] S1. In a reaction vessel, 2g of carboxylated multi-walled carbon nanotubes and 2g of 2-aminoterephthalic acid were added to 80mL of DMF and sonicated for 30min. Then, 8g of ferric chloride hexahydrate was added, and the mixture was heated to 140℃ and reacted for 20h. After cooling, the precipitate was collected by centrifugation, washed with ethanol and deionized water, and dried under vacuum at 60℃ for 10h to obtain MOF composite carbon nanotubes.

[0031] S2. In a reaction vessel, 0.8 g of diethylmethylamine and 1.5 g of 1-bromo-2-methoxyethane were dissolved in 20 mL of acetonitrile. The mixture was heated to 50 °C and reacted for 10 h under nitrogen protection. The precipitate was obtained by extraction with ethanol and dried under vacuum at 50 °C for 10 h. Then, 0.8 g of the precipitate was dissolved in 40 mL of 1 M bis(trifluoromethane)sulfonylimide lithium salt aqueous solution and stirred for 1 h. The precipitate was extracted with dichloromethane, filtered, washed with deionized water, and dried under vacuum at 50 °C for 10 h to obtain an ionic liquid.

[0032] S3. In a reaction vessel, 0.8 g of ionic liquid and 20 mL of ethanol are mixed, 3 g of MOF composite carbon nanotubes are added, and the mixture is stirred for 1 h. The ethanol is removed by rotary evaporation, and the mixture is dried under vacuum at 50 °C for 10 h to obtain the loaded MOF composite carbon nanotubes.

[0033] S4. Disperse 8g of 300-mesh nylon powder ultrasonically in 100mL of sodium hydroxide solution. The sodium hydroxide solution is prepared by mixing sodium hydroxide, dicyandiamine and deionized water in a ratio of 2g:0.8g:50mL. After stirring for 5min, add 3g of loaded MOF composite carbon nanotubes, sonicate for 1h, collect the precipitate by centrifugation, wash the precipitate with ethanol and deionized water, and vacuum dry at 60℃ for 10h to obtain conductive reinforced nylon powder.

[0034] S5. In a reaction vessel, 5g of conductive carbon black, 5g of sodium dodecylbenzenesulfonate and 60g of polyvinylidene fluoride are ultrasonically dispersed in 500g of N-methyl-2-pyrrolidone. 5g of conductive reinforced nylon powder is added and the mixture is stirred for 10h. The solution is then coated onto a glass plate with a coating thickness of 200μm and dried in an oven at 90℃ for 10h to obtain a solid electrolyte.

[0035] A method for preparing a solid-state battery includes the following steps:

[0036] A mixed solvent was prepared by mixing N-methylpyrrolidone and dimethylacetamide at a volume ratio of 3:7. Activated carbon and conductive carbon black were mixed at a mass ratio of 1:0.2 and added to the mixed solvent. After stirring and grinding, a slurry was obtained. The slurry was sprayed and dried at 90°C. Then, the slurry was compacted under a pressure of 8 MPa and sliced ​​to obtain an electrode sheet. The electrode sheet, solid electrolyte, and lithium sheet were assembled in sequence and then encapsulated in a casing to obtain a solid-state battery.

[0037] Example 2: A solid electrolyte, prepared by the following steps:

[0038] S1. In a reaction vessel, 2.5 g of carboxylated multi-walled carbon nanotubes and 3 g of 2-aminoterephthalic acid were added to 90 mL of DMF and sonicated for 35 min. Then, 9 g of ferric chloride hexahydrate was added, and the mixture was heated to 145 °C and reacted for 22 h. After cooling, the precipitate was collected by centrifugation, washed with ethanol and deionized water, and dried under vacuum at 65 °C for 11 h to obtain MOF composite carbon nanotubes.

[0039] S2. In a reaction vessel, 0.9 g of diethylmethylamine and 1.75 g of 1-bromo-2-methoxyethane were dissolved in 25 mL of acetonitrile. The mixture was heated to 55 °C and reacted for 11 h under nitrogen protection. The precipitate was obtained by extraction with ethanol and dried under vacuum at 55 °C for 11 h. Then, 1 g of the precipitate was dissolved in 45 mL of 1 M bis(trifluoromethane)sulfonylimide lithium salt aqueous solution and stirred for 1.5 h. The precipitate was extracted with dichloromethane, filtered, washed with deionized water, and dried under vacuum at 55 °C for 11 h to obtain an ionic liquid.

[0040] S3. In a reaction vessel, 0.9 g of ionic liquid and 25 mL of ethanol are mixed, 3.5 g of MOF composite carbon nanotubes are added, and the mixture is stirred for 1.5 h. The ethanol is removed by rotary evaporation, and the mixture is dried under vacuum at 55 °C for 11 h to obtain the loaded MOF composite carbon nanotubes.

[0041] S4. Disperse 9g of 350-mesh nylon powder ultrasonically in 125mL of sodium hydroxide solution. The sodium hydroxide solution is prepared by mixing sodium hydroxide, dicyandiamine and deionized water in a ratio of 2.5g:0.9g:75mL. After stirring for 7min, add 3.5g of loaded MOF composite carbon nanotubes, sonicate for 1.5h, collect the precipitate by centrifugation, wash the precipitate with ethanol and deionized water, and vacuum dry at 65℃ for 11h to obtain conductive reinforced nylon powder.

[0042] S5. In a reaction vessel, 6.5g of conductive carbon black, 5.5g of sodium dodecylbenzenesulfonate and 70g of polyvinylidene fluoride are ultrasonically dispersed in 550g of N-methyl-2-pyrrolidone. 5.5g of conductive reinforced nylon powder is added and the mixture is stirred for 11h. The solution is then coated onto a glass plate with a coating thickness of 225μm and dried in an oven at 95℃ for 11h to obtain a solid electrolyte.

[0043] A method for preparing a solid-state battery includes the following steps:

[0044] A mixed solvent was prepared by mixing N-methylpyrrolidone and dimethylacetamide at a volume ratio of 3.5:7.5. Activated carbon and conductive carbon black were mixed at a mass ratio of 1.05:0.25 and added to the mixed solvent. After stirring and grinding, a slurry was obtained. The slurry was sprayed and dried at 95°C. Then, the slurry was compacted under a pressure of 9 MPa and sliced ​​to obtain an electrode sheet. The electrode sheet, solid electrolyte, and lithium sheet were assembled in sequence and then encapsulated in a casing to obtain a solid-state battery.

[0045] Example 3: A solid electrolyte, prepared by the following steps:

[0046] S1. In a reaction vessel, 3g of carboxylated multi-walled carbon nanotubes and 4g of 2-aminoterephthalic acid were added to 100mL of DMF and sonicated for 40min. Then, 10g of ferric chloride hexahydrate was added, and the mixture was heated to 150℃ and reacted for 24h. After cooling, the precipitate was collected by centrifugation, washed with ethanol and deionized water, and dried under vacuum at 70℃ for 12h to obtain MOF composite carbon nanotubes.

[0047] By reacting the amino group in 2-aminoterephthalic acid with the carboxyl group on the surface of carboxylated multi-walled carbon nanotubes, 2-aminoterephthalic acid is grafted onto the surface of carboxylated multi-walled carbon nanotubes, thereby generating Fe-MOF with a porous structure on the surface of carboxylated multi-walled carbon nanotubes, and making the surface of MOF composite carbon nanotubes contain the amino group of Fe-MOF.

[0048] S2. In a reaction vessel, 1 g of diethylmethylamine and 2 g of 1-bromo-2-methoxyethane were dissolved in 30 mL of acetonitrile. The mixture was heated to 60 °C and reacted for 12 h under nitrogen protection. The precipitate was obtained by extraction with ethanol and dried under vacuum at 60 °C for 12 h. Then, 1.2 g of the precipitate was dissolved in 50 mL of 1 M bis(trifluoromethane)sulfonylimide lithium salt aqueous solution and stirred for 2 h. The precipitate was extracted with dichloromethane, filtered, washed with deionized water, and dried under vacuum at 60 °C for 12 h to obtain an ionic liquid.

[0049] S3. In a reaction vessel, 1g of ionic liquid and 30mL of ethanol are mixed, 4g of MOF composite carbon nanotubes are added, and the mixture is stirred for 2h. The ethanol is removed by rotary evaporation, and the mixture is dried under vacuum at 60℃ for 12h to obtain the loaded MOF composite carbon nanotubes.

[0050] Conductive ionic liquids are impregnated in MOF composite carbon nanotubes. The adsorption capacity of MOFs is used to adsorb the ionic liquids into the porous structure of MOFs. The strong adsorption capacity of the MOF porous structure can effectively reduce the loss of ionic liquids and enhance conductivity.

[0051] S4. 10g of 400-mesh nylon powder was ultrasonically dispersed in 150mL of sodium hydroxide solution. The sodium hydroxide solution was prepared by mixing sodium hydroxide, dicyandiamine and deionized water in a ratio of 3g:1g:100mL. After stirring for 10min, 4g of loaded MOF composite carbon nanotubes was added. The mixture was ultrasonically treated for 2h, and the precipitate was collected by centrifugation. The precipitate was washed with ethanol and deionized water and vacuum dried at 70℃ for 12h to obtain conductive reinforced nylon powder.

[0052] In sodium hydroxide solution, amide bonds in nylon powder hydrolyze to form carboxyl and amino groups. The carboxyl groups react rapidly with the amino groups of dicyandiamine, resulting in more amino groups on the surface of the nylon powder. Then, loaded MOF composite carbon nanotubes with amino groups on their surface are mixed with the nylon powder. Under the action of hydrogen bonding between amino groups, the loaded MOF composite carbon nanotubes and nylon powder are uniformly composited, resulting in conductive nylon powder. The nylon powder has a certain mechanical strength, and the interlaced network of the nylon powder is conducive to the formation of a conductive network, which improves the mechanical strength of the solid electrolyte and also improves its conductivity.

[0053] S5. In a reaction vessel, 8g of conductive carbon black, 6g of sodium dodecylbenzenesulfonate and 80g of polyvinylidene fluoride are ultrasonically dispersed in 600mL of N-methyl-2-pyrrolidone. 6g of conductive reinforced nylon powder is added and the mixture is stirred for 12h. The solution is then coated onto a glass plate with a coating thickness of 250μm and dried in an oven at 100℃ for 12h to obtain a solid electrolyte.

[0054] A method for preparing a solid-state battery includes the following steps:

[0055] A mixed solvent was prepared by mixing N-methylpyrrolidone and dimethylacetamide at a volume ratio of 4:8. Activated carbon and conductive carbon black were mixed at a mass ratio of 1.1:0.3 and added to the mixed solvent. After stirring and grinding, a slurry was obtained. The slurry was sprayed and dried at 100°C. Then, the slurry was compacted under a pressure of 10 MPa and sliced ​​to obtain an electrode sheet. The electrode sheet, solid electrolyte, and lithium sheet were assembled in sequence and then encapsulated in a casing to obtain a solid-state battery.

[0056] The nylon powder is designated as Nylon 6 powder.

[0057] Carboxylated multi-walled carbon nanotubes have a diameter of 10-20 nm and a length of 8-15 μm.

[0058] Comparative Example 1: The difference from Example 1 is that in S1, carboxylated multi-walled carbon nanotubes of equal mass are replaced with multi-walled carbon nanotubes, while the other steps remain unchanged, and a solid electrolyte is obtained.

[0059] Comparative Example 2: The difference from Example 1 is that in S2, MOF composite carbon nanotubes were replaced with an equal mass of carboxylated multi-walled carbon nanotubes, while the other steps remained unchanged, and a solid electrolyte was prepared.

[0060] Comparative Example 3: The difference from Example 1 is that in S5, the conductive reinforced nylon powder was replaced with an equal mass-loaded MOF composite carbon nanotube, while the other steps remained unchanged, and a solid electrolyte was obtained.

[0061] The solid electrolytes obtained in Examples 1-3 and Comparative Examples 1-3 were used to prepare CR2025 coin cells according to the solid cell preparation method in Example 1. The electrode thickness was 200 μm. The performance of the coin cells was tested. The discharge specific capacity and ionic conductivity of the cells were tested at a current density of 0.2C. After 500 charge-discharge cycles at room temperature (25°C), the discharge specific capacity of the cells was tested again, and the capacity retention rate of the cells was calculated.

[0062] The tensile strength and elongation at break of the solid electrolytes prepared in Examples 1-3 and Comparative Examples 1-3 were tested according to standard ASTM D882-10.

[0063] The results are shown in Table 1:

[0064] Table 1: Solid-State Battery Performance Test Results

[0065] project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 <![CDATA[Ionic conductivity (S·cm -1 )]]> <![CDATA[6.58×10 -4 ]]> <![CDATA[6.67×10 -4 ]]> <![CDATA[6.74×10 -4 ]]> <![CDATA[6.02×10 -4 ]]> <![CDATA[5.52×10 -4 ]]> <![CDATA[3.92×10 -4 ]]> <![CDATA[Discharge specific capacity (mAh·g -1 )]]> 172.3 173.1 173.4 164.5 156.7 127.3 Capacity retention rate (%) 91.4 91.7 91.8 89.3 81.6 72.8 Tensile strength (MPa) 17.3 17.7 18.1 16.5 16.7 11.0 Elongation at break (%) 586 591 595 562 568 387

[0066] As can be seen from Table 1, the solid electrolyte prepared by this invention has good mechanical properties, and the solid battery prepared by this invention has high ionic conductivity, high discharge specific capacity, and high capacity retention rate after 500 cycles. This indicates that the ionic liquid in the solid electrolyte prepared by this invention is well fixed, has strong cyclic conductivity, and the conductive network formed by nylon powder has good conductivity.

[0067] In Comparative Example 1, due to the lack of carboxylation on the surface of carbon nanotubes, Fe-MOF could not be uniformly generated on the carbon nanotubes, resulting in poor conductive synergy and reduced conductivity.

[0068] In Comparative Example 2, since Fe-MOF was not synthesized on the surface of carboxylated carbon nanotubes, the adsorption capacity of carboxylated carbon nanotubes for ionic liquids was poor, and the loss of ionic liquids was high after multiple cycles, resulting in a low capacity retention rate.

[0069] Comparative Example 3, due to the absence of nylon powder to form a conductive network, resulted in a solid electrolyte with lower mechanical properties, and its conductivity was also significantly reduced due to the tendency of carbon nanotubes to agglomerate.

[0070] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A solid electrolyte, characterized in that, By mass, it contains the following components: 5-6 parts conductive reinforced nylon powder, 5-8 parts conductive carbon black, 5-6 parts sodium dodecylbenzene sulfonate, 60-80 parts polyvinylidene fluoride and 500-600 parts N-methyl-2-pyrrolidone; The conductive reinforced nylon powder is prepared by the following steps: Fe-MOF was generated in situ on the surface of carboxylated multi-walled carbon nanotubes to obtain MOF composite carbon nanotubes. Ionic liquid was loaded into the MOF composite carbon nanotubes to obtain loaded MOF composite carbon nanotubes. Nylon powder was ultrasonically dispersed in sodium hydroxide solution, and after stirring, the loaded MOF composite carbon nanotubes were added. The mixture was ultrasonically treated for 1-2 hours, the precipitate was collected by centrifugation, washed, and vacuum dried to obtain conductive reinforced nylon powder. The supported MOF composite carbon nanotubes are specifically prepared by the following steps: In a reaction vessel, ionic liquid and ethanol are mixed, MOF composite carbon nanotubes are added, and the mixture is stirred for 1-2 hours. Ethanol is removed by rotary evaporation, and the MOF composite carbon nanotubes are obtained by vacuum drying. The MOF composite carbon nanotubes are specifically prepared by the following steps: Carboxylated multi-walled carbon nanotubes and 2-aminoterephthalic acid were added to DMF in a reaction vessel and sonicated for 30-40 min. Then, ferric chloride hexahydrate was added, and the temperature was raised to 140-150℃ for 20-24 h. After cooling, the precipitate was collected by centrifugation, washed, and vacuum dried to obtain MOF composite carbon nanotubes. The solid electrolyte is prepared by the following steps: Conductive carbon black, sodium dodecylbenzenesulfonate, and polyvinylidene fluoride are ultrasonically dispersed in N-methyl-2-pyrrolidone in a reaction vessel. Conductive reinforced nylon powder is added, and the mixture is stirred for 10-12 hours. The solution is then coated onto a glass plate with a thickness of 200-250 μm and dried in an oven at 90-100 °C for 10-12 hours to obtain a solid electrolyte.

2. The solid electrolyte according to claim 1, characterized in that, The ratio of nylon powder, sodium hydroxide solution, and supported MOF composite carbon nanotubes is 8-10g: 100-150mL: 3-4g; the sodium hydroxide solution is prepared by mixing sodium hydroxide, dicyandiamine, and deionized water in a ratio of 2-3g: 0.8-1g: 50-100mL.

3. A solid electrolyte according to claim 1, characterized in that, The ratio of the ionic liquid, ethanol, and MOF composite carbon nanotubes is 0.8-1g: 20-30mL: 3-4g.

4. A solid electrolyte according to claim 3, characterized in that, The ionic liquid is prepared by the following steps: Diethylmethylamine and 1-bromo-2-methoxyethane were dissolved in acetonitrile in a reaction vessel and reacted at 50-60℃ for 10-12 h under nitrogen protection. The precipitate was obtained by leaching with ethanol, and after vacuum drying, it was dissolved in a 1M aqueous solution of lithium bis(trifluoromethane)sulfonylimide. The reaction was stirred for 1-2 h, and the precipitate was extracted with dichloromethane. The precipitate was filtered, washed, and then vacuum dried to obtain an ionic liquid.

5. A solid electrolyte according to claim 4, characterized in that, The ratio of diethylmethylamine, 1-bromo-2-methoxyethane, and acetonitrile is 0.8-1g:1.5-2g:20-30mL.

6. A solid electrolyte according to claim 1, characterized in that, The ratio of carboxylated multi-walled carbon nanotubes, 2-aminoterephthalic acid, DMF and ferric chloride hexahydrate is 2-3g: 2-4g: 80-100mL: 8-10g.

7. A method for preparing a solid-state battery, characterized in that, Includes the following steps: N-methylpyrrolidone and dimethylacetamide were mixed to prepare a mixed solvent. Activated carbon and conductive carbon black were added to the mixed solvent. After stirring and grinding, a slurry was obtained. The slurry was sprayed and dried. Then, after compaction and slicing, an electrode sheet was obtained. The electrode sheet, solid electrolyte and lithium sheet were assembled in sequence. After being assembled and covered by a shell, a solid battery was obtained. The solid electrolyte is the solid electrolyte described in any one of claims 1-6.

8. A solid-state battery, characterized in that, It is prepared by the method for preparing a solid-state battery according to claim 7.