Solid-state battery containing gel-state composite solid electrolyte and preparation method of solid-state battery

Abstract

The invention discloses a solid-state battery containing a gel-state composite solid electrolyte and a preparation method of the solid-state battery. The preparation method comprises the following steps: S1, soaking a diaphragm in a heteropolyacid solution to obtain a heteropolyacid-loaded diaphragm; s2, soaking the heteropolyacid loaded diaphragm in an ammonium salt solution to obtain a heteropolyacid salt loaded diaphragm; and S3, assembling the heteropolyacid salt loaded diaphragm, a positive pole piece and a negative pole piece into a battery cell, and injecting an epoxy compound containing lithium salt into the battery cell to initiate a polymerization reaction so as to form the gel-state composite solid electrolyte in situ. The gel-state composite solid electrolyte disclosed by the invention has relatively high ionic conductivity and mechanical strength, rapid transmission of lithium ions is ensured, and concentration polarization of a solid-state battery is reduced. Meanwhile, the preparation method of the gel-state composite solid electrolyte is simple, mild in reaction condition and suitable for large-scale production. And the assembled solid-state battery shows higher energy density and safety.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy power batteries, and in particular to a solid-state battery comprising a gel-state composite solid electrolyte and a preparation method thereof. Background Art

[0002] In recent years, the development of electric vehicles has pushed the demand for key performance indicators of lithium-ion batteries, such as energy density, safety, and service life, to new heights. Solid-state lithium batteries utilize solid ion conductors to replace traditional liquid electrolytes. These batteries offer advantages such as lower electrolyte flammability and more stable electrochemical performance, making them one of the most competitive solutions to overcome the performance bottlenecks of traditional liquid lithium-ion batteries. However, while achieving high energy density, current solid-state batteries often suffer from poor electrochemical stability, poor interfacial contact, and low ionic conductivity. Polymer solid electrolytes offer advantages such as low cost, good interfacial contact, and ease of production and processing, offering broad application prospects. Gel electrolytes prepared through in-situ polymerization have emerged as a promising method for preparing solid-state electrolytes, offering significant advantages in processing and cost. However, in-situ polymerization also presents challenges such as harsh polymerization conditions, rapid polymerization rates leading to rapid polymerization, and difficulty controlling molecular weight. Currently, most in-situ polymerized solid electrolytes use epoxy compounds as monomers. However, the ether bonds formed by these monomers are not resistant to oxidation and can form free radicals in high-voltage ternary cathode material systems, requiring the addition of free radical scavengers, which can reduce electrochemical performance. Summary of the Invention

[0003] The purpose of the present invention is to provide a solid-state battery containing a gel-state composite solid electrolyte and a preparation method thereof. The heteropolyacid introduced in the present invention can not only serve as an initiator, but also the terminal oxygen and bridging oxygen atoms on the surface provide transmission sites for lithium ions. Most importantly, it can also serve as a free radical scavenger to improve the antioxidant capacity of the solid electrolyte. It not only effectively solves the problems of poor interface contact and high-voltage resistance between the solid electrolyte and the electrode, but also has a controllable reaction rate, a simple preparation method, mild polymerization reaction conditions, and is suitable for large-scale production.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] In a first aspect, the present invention provides a method for preparing a solid-state battery comprising a gel composite solid electrolyte, comprising the following steps:

[0006] S1, soaking the diaphragm in a heteropoly acid solution to obtain a heteropoly acid-loaded diaphragm;

[0007] S2, soaking the heteropolyacid-loaded diaphragm in an ammonium salt solution, so that the ammonium salt enters the pores of the diaphragm and reacts with the heteropolyacid molecules to form a heteropolyacid salt, thereby obtaining a heteropolyacid-loaded diaphragm;

[0008] S3, assembling the heteropolyacid-loaded separator, the positive electrode sheet, and the negative electrode sheet into a battery cell, injecting an epoxy compound containing a lithium salt into the battery cell to initiate a polymerization reaction, so as to form a gel composite solid electrolyte in situ, thereby obtaining the solid-state battery containing the gel composite solid electrolyte;

[0009] The epoxy compound includes one or more of 1,3-dioxolane, tetrahydrofuran, oxetane, 1,4-dioxane, and 1,3,5-trioxane.

[0010] Based on the above technical solution, the present invention uses inorganic solid polyoxometalate as an initiator to cause the epoxy compound to undergo ring-opening polymerization in situ to obtain a gel electrolyte, which has the advantages of controllable reaction rate, high ionic conductivity, wide electrochemical window, high ion migration number and good interface compatibility with the electrode. In addition, the gel composite solid electrolyte has high ionic conductivity and mechanical strength, which can ensure the rapid transmission of lithium ions and reduce the concentration polarization of the solid-state battery. The assembled solid-state battery exhibits higher energy density and safety.

[0011] In the above preparation method, further, the diaphragm includes one or more of a PE diaphragm, a PP diaphragm, a ceramic-coated PE composite diaphragm, and a ceramic-coated PP composite diaphragm;

[0012] The thickness of the separator is 5-15 μm, such as 7 μm.

[0013] In the above preparation method, further, the heteropoly acid includes one or more of phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, and silicomolybdic acid;

[0014] The concentration of the heteropolyacid solution is 0.01 mol / L to 1 mol / L, such as 0.1 mol / L;

[0015] The solvent in the heteropolyacid solution includes any one of ethanol, ethylene glycol, glycerol, 1,3-butanediol, and water;

[0016] The soaking time in step S1 is 6 hours to 48 hours, such as 24 hours.

[0017] In the above preparation method, further, the ammonium salt solution includes one or more of ammonia water, ammonium chloride solution, ammonium bromide solution, and tetrabutylammonium bromide solution;

[0018] The concentration of the ammonium salt solution is 0.1 mol / L to 5 mol / L, such as 1 mol / L;

[0019] The solvent in the ammonium salt solution is water;

[0020] The soaking time in step S2 is 6 hours to 48 hours, such as 24 hours.

[0021] In the above preparation method, further, the positive electrode active material in the positive electrode plate includes any one of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, and lithium manganese iron phosphate, such as NCM811;

[0022] The negative electrode active material in the negative electrode plate includes any one of silicon-carbon doped graphite, graphite, hard carbon, and lithium titanate, such as commercially available graphite doped with 10% silicon-carbon.

[0023] In the above preparation method, further, the injection amount of the epoxy compound containing lithium salt is 100g to 500g, such as 200g.

[0024] In the above preparation method, further, the lithium salt includes one or more of lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium tetrafluoroborate (LiBF4);

[0025] The concentration of the lithium salt in the epoxy compound is 0.1 mol / L to 5 mol / L, such as 0.1 mol / L.

[0026] In the above preparation method, further, the polymerization reaction temperature is 20-70° C., such as 45° C., and the time is 6 h to 48 h, such as 24 h.

[0027] In the above preparation method, further, the method further comprises the step of washing the diaphragm with deionized water to remove excess heteropolyacid molecules on the surface after the soaking in step S1; and / or,

[0028] After the soaking in step S2 is completed, the method further includes the steps of washing the membrane with deionized water to remove excess ammonium salt on the surface and drying the membrane. Preferably, the drying temperature is 80-100°C, such as drying at 80°C.

[0029] In a second aspect, the present invention provides a solid-state battery comprising a gel composite solid electrolyte prepared by the method described in any one of the above.

[0030] The present invention has the following beneficial effects:

[0031] 1) The present invention forms a gel composite electrolyte in situ in a square battery by initiating epoxide ring-opening polymerization through solid polyoxometalate. The preparation method of the solid electrolyte is simple, the polymerization reaction conditions are mild, and it is suitable for large-scale production.

[0032] 2) The solid polyoxometalate used as an initiator in the present invention has a controllable reaction rate and does not cause implosion. Furthermore, the abundant surface oxygen atoms of the polyoxometalate promote rapid lithium ion transport. Furthermore, the ammonium cations of the polyoxometalate can electrostatically bind to the anions in LiTFSI, inhibiting anion movement and reducing concentration polarization in solid-state batteries.

[0033] 3) The gel composite electrolyte prepared by the present invention has the advantages of high ionic conductivity, wide electrochemical window, high ion migration number and good interfacial compatibility with electrodes.

[0034] 4) The epoxy compound selected in the present invention is rich in oxygen atoms, wherein the oxygen atoms can form a weak coordination effect with lithium ions, thereby promoting lithium ion conduction through chain segment movement.

[0035] 5) The solid-state battery prepared by the present invention can be used with high-voltage nickel cobalt manganese oxide (NCM811) and silicon-carbon negative electrodes, and exhibits higher energy density and smaller internal resistance compared to liquid battery systems. DETAILED DESCRIPTION

[0036] The present invention will be further described in detail below in conjunction with specific embodiments. The examples provided are only for illustrating the present invention and are not intended to limit the scope of the present invention. The examples provided below can serve as a guide for further improvements by those skilled in the art and are not intended to limit the present invention in any way.

[0037] Unless otherwise specified, the methods used in the following examples are all conventional methods and are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials, reagents, etc. used in the following examples are all commercially available unless otherwise specified.

[0038] Example 1: Preparation of a solid-state battery containing a gel composite solid electrolyte

[0039] The following steps are followed to in situ polymerize the gel composite solid electrolyte in a solid-state battery:

[0040] 1) Modification of the diaphragm

[0041] A 7μm thick PE membrane was soaked in a 0.1mol / L ethanol solution of phosphotungstic acid for 24 hours. After the soaking, the excess phosphotungstic acid molecules on the membrane surface were removed with deionized water. Then, it was placed in a 1mol / L ammonia solution and soaked for 24 hours. After the soaking, it was taken out and washed with excess deionized water. The membrane was dried at 80°C to obtain an ammonium phosphotungstate-modified membrane.

[0042] 2) Assembly of gel-state solid-state batteries

[0043] The commercial ternary materials NCM811, SP, and PVDF were made into a slurry in a ratio of 96.5:1.5:2 and coated on the aluminum current collector as the positive electrode. Graphite doped with 10% silicon carbon, SP, CMC, and PAA were coated on the copper current collector in a ratio of 96:1:1:2 as the negative electrode. The PE separator modified with ammonium phosphotungstate and the positive and negative electrodes were assembled into a square battery cell with a capacity of 21Ah through a winding process. 200g of 0.1mol / L LiTFSI 1,3-dioxolane electrolyte was added to the battery cell, and ring-opening polymerization was carried out at 45°C for 24h to form a gel-state solid-state battery.

[0044] Example 2: Preparation of a solid-state battery containing a gel composite solid electrolyte

[0045] The following steps are followed to in situ polymerize the gel composite solid electrolyte in a solid-state battery:

[0046] 1) Modification of the diaphragm

[0047] A 7μm thick PE membrane was soaked in a 0.1mol / L ethanol solution of silicotungstic acid for 24 hours. After soaking, the excess silicotungstic acid molecules on the membrane surface were removed with deionized water. Then, it was placed in a 1mol / L ammonia solution and soaked for 24 hours. After soaking, it was taken out and washed with excess deionized water. The membrane was dried at 80°C to obtain an ammonium silicotungstate-modified membrane.

[0048] 2) Assembly of gel-state solid-state batteries

[0049] The commercial ternary materials NCM811, SP, and PVDF were made into a slurry in a ratio of 96.5:1.5:2 and coated on the aluminum current collector as the positive electrode. Graphite doped with 10% silicon carbon, SP, CMC, and PAA were coated on the copper current collector in a ratio of 96:1:1:2 as the negative electrode. The PE separator modified with ammonium silicotungstate and the positive and negative electrodes were assembled into a square battery cell with a capacity of 21Ah through a winding process. 200g of 0.1mol / L LiTFSI 1,3-dioxolane electrolyte was added to the battery cell, and ring-opening polymerization was carried out at 45°C for 24h to form a gel-state solid-state battery.

[0050] Example 3: Preparation of a solid-state battery containing a gel composite solid electrolyte

[0051] The following steps are followed to in situ polymerize the gel composite solid electrolyte in a solid-state battery:

[0052] 1) Modification of the diaphragm

[0053] A 7μm thick PE membrane was soaked in a 0.1mol / L ethanol solution of phosphomolybdic acid for 24 hours. After the soaking, the excess phosphomolybdic acid molecules on the membrane surface were removed with deionized water; then it was placed in a 1mol / L ammonia solution and soaked for 24 hours. After the soaking, it was taken out and washed with excess deionized water. The membrane was dried at 80°C to obtain an ammonium phosphomolybdate-modified membrane.

[0054] 2) Assembly of gel-state solid-state batteries

[0055] The commercial ternary materials NCM811, SP, and PVDF were made into a slurry in a ratio of 96.5:1.5:2 and coated on the aluminum current collector as the positive electrode. Graphite doped with 10% silicon carbon, SP, CMC, and PAA were coated on the copper current collector in a ratio of 96:1:1:2 as the negative electrode. The PE separator modified with ammonium phosphomolybdate and the positive and negative electrodes were assembled into a square battery cell with a capacity of 21Ah through a winding process. 200g of 0.1mol / L LiTFSI 1,3-dioxolane electrolyte was added to the battery cell, and ring-opening polymerization was carried out at 45°C for 24h to form a gel-state solid-state battery.

[0056] Example 4: Preparation of a solid-state battery containing a gel composite solid electrolyte

[0057] The following steps are followed to in situ polymerize the gel composite solid electrolyte in a solid-state battery:

[0058] 1) Modification of the diaphragm

[0059] A 7μm thick PE membrane was soaked in a 0.1mol / L ethanol solution of phosphotungstic acid for 24 hours. After the soaking, the excess phosphotungstic acid molecules on the membrane surface were removed with deionized water. Then, it was placed in a 1mol / L ammonia solution and soaked for 24 hours. After the soaking, it was taken out and washed with excess deionized water. The membrane was dried at 80°C to obtain an ammonium phosphotungstate-modified membrane.

[0060] 2) Assembly of gel-state solid-state batteries

[0061] The commercial ternary materials NCM811, SP, and PVDF were made into a slurry in a ratio of 96.5:1.5:2 and coated on the aluminum current collector as the positive electrode. Graphite doped with 10% silicon carbon, SP, CMC, and PAA were coated on the copper current collector in a ratio of 96:1:1:2 as the negative electrode. The PE separator modified with ammonium phosphotungstate and the positive and negative electrodes were assembled into a square battery cell with a capacity of 21Ah through a winding process. 200g of 0.1mol / L LiTFSI tetrahydrofuran electrolyte was added to the battery cell, and ring-opening polymerization was carried out at 45°C for 24h to form a gel-state solid-state battery.

[0062] Example 5: Preparation of a solid-state battery containing a gel composite solid electrolyte

[0063] The following steps are followed to in situ polymerize the gel composite solid electrolyte in a solid-state battery:

[0064] 1) Modification of the diaphragm

[0065] A 7μm thick PE membrane was soaked in a 0.1mol / L ethanol solution of phosphotungstic acid for 24 hours. After the soaking, the excess phosphotungstic acid molecules on the membrane surface were removed with deionized water. Then, it was placed in a 1mol / L ammonia solution and soaked for 24 hours. After the soaking, it was taken out and washed with excess deionized water. The membrane was dried at 80°C to obtain an ammonium phosphotungstate-modified membrane.

[0066] 2) Assembly of gel-state solid-state batteries

[0067] The commercial ternary materials NCM811, SP, and PVDF were made into a slurry in a ratio of 96.5:1.5:2 and coated on the aluminum current collector as the positive electrode. Graphite doped with 10% silicon carbon, SP, CMC, and PAA were coated on the copper current collector in a ratio of 96:1:1:2 as the negative electrode. The PE separator modified with ammonium phosphotungstate and the positive and negative electrodes were assembled into a square battery cell with a capacity of 21Ah through a winding process. 200g of 0.1mol / L LiTFSI oxetane electrolyte was added to the battery cell, and ring-opening polymerization was carried out at 45°C for 24h to form a gel-state solid-state battery.

[0068] Example 6: Preparation of a solid-state battery containing a gel composite solid electrolyte

[0069] The following steps are followed to in situ polymerize the gel composite solid electrolyte in a solid-state battery:

[0070] 1) Modification of the diaphragm

[0071] A 7μm thick PE membrane was soaked in a 0.1mol / L ethanol solution of phosphotungstic acid for 24 hours. After the soaking, the excess phosphotungstic acid molecules on the membrane surface were removed with deionized water. Then, it was placed in a 1mol / L ammonia solution and soaked for 24 hours. After the soaking, it was taken out and washed with excess deionized water. The membrane was dried at 80°C to obtain an ammonium phosphotungstate-modified membrane.

[0072] 2) Assembly of gel-state solid-state batteries

[0073] The commercial ternary materials NCM811, SP, and PVDF were made into a slurry in a ratio of 96.5:1.5:2 and coated on the aluminum current collector as the positive electrode. Graphite doped with 10% silicon carbon, SP, CMC, and PAA were coated on the copper current collector in a ratio of 96:1:1:2 as the negative electrode. The PE separator modified with ammonium phosphotungstate and the positive and negative electrodes were assembled into a square battery cell with a capacity of 21Ah through a winding process. 200g of 0.1mol / L LiTFSI 1,4-dioxane electrolyte was added to the battery cell, and ring-opening polymerization was carried out at 45°C for 24h to form a gel-state solid-state battery.

[0074] Example 7: Preparation of a solid-state battery containing a gel composite solid electrolyte

[0075] The following steps are followed to in situ polymerize the gel composite solid electrolyte in a solid-state battery:

[0076] 1) Modification of the diaphragm

[0077] A 7μm thick PE membrane was soaked in a 0.1mol / L ethanol solution of phosphotungstic acid for 24 hours. After the soaking, the excess phosphotungstic acid molecules on the membrane surface were removed with deionized water. Then, it was placed in a 1mol / L ammonia solution and soaked for 24 hours. After the soaking, it was taken out and washed with excess deionized water. The membrane was dried at 80°C to obtain an ammonium phosphotungstate-modified membrane.

[0078] 2) Assembly of gel-state solid-state batteries

[0079] The commercial ternary materials NCM811, SP, and PVDF were made into a slurry in a ratio of 96.5:1.5:2 and coated on the aluminum current collector as the positive electrode. Graphite doped with 10% silicon carbon, SP, CMC, and PAA were coated on the copper current collector in a ratio of 96:1:1:2 as the negative electrode. The PE separator modified with ammonium phosphotungstate and the positive and negative electrodes were assembled into a battery cell through a winding process. 200g of 0.1mol / L LiTFSI 1,3,5-trioxane electrolyte was added to the battery cell, and ring-opening polymerization was carried out at 45°C for 24h to form a gel-state solid-state battery.

[0080] Comparative Example 1

[0081] The commercial ternary materials NCM811, SP, and PVDF were made into a slurry in a ratio of 96.5:1.5:2 and coated on the aluminum current collector as the positive electrode. Graphite doped with 10% silicon carbon, SP, CMC, and PAA were coated on the copper current collector in a ratio of 96:1:1:2 as the negative electrode. A 7μm-thick PE separator and the positive and negative electrodes were assembled into a battery cell through a winding process. 90g of a 0.1mol / L mixed electrolyte of lithium hexafluorophosphate, ethylene carbonate and dimethyl carbonate (volume ratio 1:1) was added to the battery cell to form a liquid battery.

[0082] Comparative Example 2

[0083] The commercial ternary materials NCM811, SP, and PVDF were made into a slurry in a ratio of 96.5:1.5:2 and coated on the aluminum current collector as the positive electrode. Graphite doped with 10% silicon carbon, SP, CMC, and PAA were coated on the copper current collector in a ratio of 96:1:1:2 as the negative electrode. The 7μm thick PE separator and the positive and negative electrodes were assembled into a battery cell through a winding process. 90g of a mixed electrolyte of 0.1mol / L lithium hexafluorophosphate and 1,3-dioxolane was added to the battery cell, and ring-opening polymerization was carried out at 45°C for 24h to form a gel-state solid-state battery.

[0084] Performance test case

[0085] Battery performance test: The batteries of the embodiment and comparative example were subjected to charge and discharge curve test, which was performed by charging to 4.2V at 0.5C constant current, charging to 0.05C constant voltage cut-off, and discharging to 2.8V at 0.5C constant current.

[0086] The measured battery capacity, first discharge capacity, first efficiency, and impedance test results are shown in Table 1:

[0087] Table 1. Battery performance test results

[0088]

[0089] As can be seen from Table 1, by comprehensively comparing Examples 1-3, it can be seen that the gram capacity of the solid-state battery assembled using phosphotungstic acid as an initiator is higher, and the capacity retention rate after 500 cycles is better. Comparing Examples 1 and 4-7, it can be seen that the solid-state battery assembled in Example 7 exhibits better electrochemical performance. This is because the oxygen atom content of 1,3,5-trioxane is relatively high, and the ether bond formed after ring opening promotes lithium ion transmission. Comparing Example 1 and Comparative Example 2, it can be seen that the solid-state battery assembled using phosphotungstic acid as an initiator has a higher capacity retention rate after 500 cycles.

[0090] The present invention has been described in detail above. For those skilled in the art, without departing from the purpose and scope of the present invention, can implement the present invention in a wider range under equivalent parameters, concentration and conditions. Although the present invention provides specific embodiments, it should be understood that the present invention can be further improved. In a word, according to the principle of the present invention, the application is intended to include any variation, purposes or improvements of the present invention, including departing from the disclosed scope in the application and the changes made with conventional techniques known in the art.

Claims

1. A method for preparing a solid-state battery comprising a gel composite solid electrolyte, characterized in that: The steps include: S1, soaking the diaphragm in a heteropoly acid solution to obtain a heteropoly acid-loaded diaphragm; S2, soaking the heteropolyacid-loaded diaphragm in an ammonium salt solution, so that the ammonium salt enters the pores of the diaphragm and reacts with the heteropolyacid molecules to form a heteropolyacid salt, thereby obtaining a heteropolyacid-loaded diaphragm; S3, assembling the heteropolyacid-loaded separator, the positive electrode sheet, and the negative electrode sheet into a battery cell, injecting an epoxy compound containing a lithium salt into the battery cell to initiate a polymerization reaction, so as to form a gel composite solid electrolyte in situ, thereby obtaining the solid-state battery containing the gel composite solid electrolyte; The epoxy compound includes one or more of 1,3-dioxolane, tetrahydrofuran, oxetane, 1,4-dioxane, and 1,3,5-trioxane.

2. The method for preparing a solid-state battery comprising a gel composite solid electrolyte according to claim 1, wherein: The diaphragm includes one or more of a PE diaphragm, a PP diaphragm, a ceramic-coated PE composite diaphragm, and a ceramic-coated PP composite diaphragm; The thickness of the separator is 5 to 15 μm.

3. The method for preparing a solid-state battery comprising a gel composite solid electrolyte according to claim 1, wherein: The heteropoly acid includes one or more of phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, and silicomolybdic acid; The concentration of the heteropolyacid solution is 0.01 mol / L to 1 mol / L; The solvent in the heteropolyacid solution includes any one of ethanol, ethylene glycol, glycerol, 1,3-butanediol, and water; The soaking time in step S1 is 6 hours to 48 hours.

4. The method for preparing a solid-state battery comprising a gel composite solid electrolyte according to claim 1, wherein: The ammonium salt solution includes one or more of ammonia water, ammonium chloride solution, ammonium bromide solution, and tetrabutylammonium bromide solution; The concentration of the ammonium salt solution is 0.1 mol / L to 5 mol / L; The solvent in the ammonium salt solution is water; The soaking time in step S2 is 6 hours to 48 hours.

5. The method for preparing a solid-state battery comprising a gel composite solid electrolyte according to claim 1, wherein: The positive electrode active material in the positive electrode plate includes any one of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, and lithium manganese iron phosphate; The negative electrode active material in the negative electrode plate includes any one of silicon-carbon doped graphite, graphite, hard carbon, and lithium titanate.

6. The method for preparing a solid-state battery comprising a gel composite solid electrolyte according to claim 1, wherein: The injection amount of the epoxy compound containing lithium salt is 100g to 500g.

7. The method for preparing a solid-state battery comprising a gel composite solid electrolyte according to claim 1, wherein: The lithium salt includes one or more of lithium bis(trifluoromethanesulfonyl imide), lithium bis(fluorosulfonyl imide), and lithium tetrafluoroborate; The concentration of the lithium salt in the epoxy compound is 0.1 mol / L to 5 mol / L.

8. The method for preparing a solid-state battery comprising a gel composite solid electrolyte according to claim 1, wherein: The polymerization reaction temperature is 20-70° C., and the reaction time is 6-48 hours.

9. The method for preparing a solid-state battery comprising a gel composite solid electrolyte according to claim 1, wherein: The method further comprises, after the soaking in step S1, the step of washing the diaphragm with deionized water to remove excess heteropolyacid molecules on the surface; and / or, After the soaking in step S2 is completed, the method further includes the steps of washing the diaphragm with deionized water to remove excess ammonium salt on the surface and drying the diaphragm.

10. A solid-state battery comprising a gel composite solid electrolyte prepared by the method according to any one of claims 1 to 9.

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