Application of phenyl isocyanate, solid-state battery polymer electrolyte membrane prepared from phenyl isocyanate and all-solid-state lithium ion battery

Abstract

The invention discloses application of phenyl isocyanate, a solid-state battery polymer electrolyte membrane prepared from the phenyl isocyanate and an all-solid-state lithium ion battery. Phenyl isocyanate is used as a functional additive of a solid-state battery polymer electrolyte, and the addition amount of phenyl isocyanate is 0.5-5wt% of the mass of the solid-state battery polymer electrolyte. The structural formula of the phenyl isocyanate is # imgabs0 #, wherein R1-R5 are independently hydrogen atoms, halogen atoms, methoxyl groups, acetyl groups or alkyl groups containing 1-6 carbon atoms. The phenyl isocyanate disclosed by the invention has high reaction activity and solubility, so that the dissolution of electrolyte (lithium) salt in the electrolyte of the lithium ion battery is obviously improved, and the conductivity and transfer number of the lithium ion battery are improved. Meanwhile, the phenyl isocyanate additive and the electrolyte salt form an ionic complex, so that an effective SEI film can be formed, the high-temperature performance and the cycle performance of the polymer solid electrolyte are remarkably enhanced, and the overall safety performance of the battery is further greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solid-state batteries, and specifically relates to the use of phenyl isocyanate, a solid-state battery polymer electrolyte membrane prepared therefrom, and an all-solid-state lithium-ion battery. Background Art

[0002] With the rapid development of the new energy industry, lithium-ion batteries play an indispensable role in promoting the development of the renewable energy economy. Due to their advantages such as high energy density, long cycle life, high efficiency, and fast charge and discharge capabilities, these batteries have been widely used in mobile electronic devices, electric vehicles, and large-scale energy storage systems. However, the commonly used organic liquid electrolyte system in current commercial lithium-ion batteries has significant safety hazards. Although such electrolytes have excellent ionic conduction properties, their defects such as volatility, flammability, and explosiveness have been reported many times, becoming the key factors restricting the safety performance of the batteries.

[0003] In contrast, solid electrolyte systems exhibit significant advantages. Such materials not only possess characteristics such as non-volatility, high temperature resistance, corrosion resistance, and chemical stability, but in addition, solid electrolytes also have unique advantages such as a wide electrochemical stability window, a broad working temperature range, and flexible designability. They can also effectively reduce the side reaction activity with metallic lithium. Solid electrolytes can, to a certain extent, inhibit the growth of lithium dendrites and avoid the common leakage problems of liquid electrolytes. However, they still face the risk of structural damage caused by the piercing of lithium dendrites, which may affect the overall service life of the battery. In addition, the ionic conduction performance of solid electrolytes is relatively poor compared to liquid electrolytes.

[0004] In the solid electrolyte system, adding some functional additives to the solid polymer electrolyte is a method to improve the cycle performance of solid-state batteries, and its preparation process has significant characteristics. This material adopts a strategy of first synthesis and then assembly, that is, the preparation of the polymer electrolyte is completed outside the battery system, and then it is integrated into the battery through processes such as coating or impregnation. This preparation method can not only achieve precise regulation and optimization of material properties, but also break through the limitations of the internal battery environment on the synthesis process. However, the current solid-state batteries still need to be further improved in terms of heat resistance and cycle performance. Summary of the Invention

[0005] To address the above problems, the present invention aims to provide a use of phenyl isocyanate, a solid-state battery polymer electrolyte membrane prepared therefrom, and an all-solid-state lithium-ion battery. The selected polymer matrix and additives can polymerize to form a precursor solution at room temperature and form a solid electrolyte membrane after drying in an oven, which can improve the cycling and high-temperature stability of the solid electrolyte. The phenyl isocyanate additives of the present invention have high reactivity and solubility, which improve the dissolution of the electrolyte (lithium) salt in the lithium-ion battery polymer electrolyte, enhance the stability of the lithium-ion battery polymer electrolyte, and exhibit more stable cycling performance for the lithium-ion battery. At the same time, the phenyl isocyanate additives can form an effective SEI film by forming ion complexes with the electrolyte salt, and this additive significantly enhances the high-temperature performance and cycling performance of the polymer solid electrolyte. This property is crucial for alleviating the swelling phenomenon of the silicon-carbon electrode during the charge-discharge cycle of the solid-state battery, thereby greatly improving the overall safety performance of the battery.

[0006] To solve the above technical problems, the technical solutions adopted in the present invention are as follows:

[0007] A use of phenyl isocyanate as a functional additive for a solid-state battery polymer electrolyte, wherein the addition amount of phenyl isocyanate is 0.5-5 wt% of the mass of the solid-state battery polymer electrolyte; the structural formula of phenyl isocyanate is:

[0008]

[0009] wherein, R1 to R5 are independently a hydrogen atom, a halogen atom, a methoxy group, an acetyl group, or an alkyl group containing 1 to 6 carbon atoms.

[0010] The above phenyl isocyanate has high reactivity and solubility, which significantly improves the dissolution of the electrolyte (lithium) salt in the lithium-ion battery electrolyte, increases the conductivity and transference number of the lithium-ion battery. At the same time, the phenyl isocyanate additives can form an effective SEI film by forming ion complexes with the electrolyte salt, and significantly enhance the high-temperature performance and cycling performance of the polymer solid electrolyte. This property is crucial for alleviating the swelling phenomenon of the silicon-carbon electrode during the charge-discharge cycle of the solid-state battery, thereby greatly improving the overall safety performance of the battery.

[0011] Unless otherwise specified in this application, all are mass percentages.

[0012] To improve the cycling performance of the battery, the phenyl isocyanate is preferably at least one of 4-(trifluoromethyl)phenyl isocyanate, 4-chloro-3-(trifluoromethyl)phenyl isocyanate, 3,5-bis(trifluoromethyl)phenyl isocyanate, 4-acetylphenyl isocyanate, 2-chloro-4-(trifluoromethyl)phenyl isocyanate, 2-(trifluoromethyl)phenyl isocyanate, 2-(trifluoromethoxy)phenyl isocyanate, 4-fluoro-3-methylphenyl isocyanate, 2-fluoro-5-methylphenyl isocyanate, 3,4-dimethylphenyl isocyanate or 3,4,5-trimethoxyphenyl isocyanate. Further preferably, the phenyl isocyanate is 3,4,5-trimethoxyphenyl isocyanate, 2-(trifluoromethoxy)phenyl isocyanate or 4-acetylphenyl isocyanate (4-acetylphenyl isocyanate). More preferably, it is 3,4,5-trimethoxyphenyl isocyanate and 2-(trifluoromethoxy)phenyl isocyanate, and most preferably 3,4,5-trimethoxyphenyl isocyanate.

[0013] The structural formulas of the various phenyl isocyanate additives are as follows:

[0014]

[0015]

[0016] A solid-state battery polymer electrolyte membrane, the raw materials of which include: 0.5-5% of the phenyl isocyanate described in claim 1 or 2, 0.5-5% of a film-forming additive, 3-10% of a polymer matrix, 70-90% of an organic solvent, and 3-10% of a lithium salt, and the foregoing percentages are all mass percentages;

[0017] The polymer matrix is at least one of polyethylene oxide - polypropylene oxide, polyethylene oxide - polymethyl methacrylate, poly(vinylidene fluoride - hexafluoropropylene) copolymer or poly(vinylidene fluoride - chlorotrifluoroethylene) copolymer.

[0018] In order to balance the film-forming effect and the improvement of battery performance, the film-forming additive is at least one of vinylene carbonate, 1,3-propane sultone, 1,4-butane sultone, acrylic lactone, ethylene vinyl carbonate, fluorinated ethylene carbonate, lithium difluorophosphate, lithium bis(oxalato)borate or lithium bis(trifluoromethanesulfonyl)imide.

[0019] The inventors found during the experiment that there is an obvious synergistic promotion effect between the above film-forming additive and the phenyl isocyanate of the present application. When the phenyl isocyanate of the present application and the above film-forming additive are added simultaneously, the cycling performance of the battery is significantly improved.

[0020] The above film-forming additive is preferably fluorinated ethylene carbonate.

[0021] The above-mentioned lithium salt is at least one of lithium hexafluorophosphate, lithium perchlorate, lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluoro(oxalato)borate, or lithium tetrafluoroborate.

[0022] To improve the cycling performance of the battery, the above-mentioned lithium salt is preferably lithium bis(trifluoromethanesulfonyl)imide. The inventor found during the experiment that lithium bis(trifluoromethanesulfonyl)imide has a good synergistic promotion effect with phenyl isocyanate of the present application.

[0023] The above-mentioned organic solvent is at least one of adiponitrile, tetrahydrofuran, diethyl sulfite, dimethylacetamide, γ-butyrolactone, acetone, ethylene carbonate, methyl acetate, ethyl acetate, propylene carbonate, butylene carbonate, 1-methyl-2-pyrrolidone, dimethyl carbonate, or ethylene carbonate.

[0024] The preparation method of the above-mentioned solid-state battery polymer electrolyte membrane includes the following steps: uniformly mixing a polymer matrix, an organic solvent, and a lithium salt to obtain a mixed solution; then adding phenyl isocyanate and a film-forming additive to the mixed solution and stirring for 6 to 12 hours to obtain a precursor solution; and then coating the precursor solution on a polytetrafluoroethylene mold of a flat plate and drying at 40 to 80 °C for 8 to 14 hours to obtain a polymer solid electrolyte membrane.

[0025] A all-solid-state lithium-ion battery contains the above-mentioned solid-state battery polymer electrolyte membrane, and its structure includes a positive electrode case - spring piece - stainless steel gasket - positive electrode - polymer solid electrolyte membrane - negative electrode - stainless steel gasket - negative electrode case connected in sequence.

[0026] The preparation method of the above-mentioned positive electrode is as follows: mixing a positive electrode active material, a conductive additive, and a binder according to a mass percentage of 80% to 90%: 5% to 10%: 5% to 10%, dissolving them into a uniform slurry with N-methylpyrrolidone (NMP), and the final slurry should just flow. Scraping and coating it on an aluminum foil, placing it in a vacuum oven at 80 °C to 120 °C and drying for 12h to 24h, cutting it into small round pieces with a diameter of 12 mm, and storing it in a glove box.

[0027] The above-mentioned positive electrode active material is selected from any one or more of lithium cobaltate (LiCoO2), lithium nickelate (LiNiO2), lithium iron phosphate (LiFeO4), and lithium nickel cobalt manganese oxide (NCM). The conductive additive is selected from any one or more of conductive carbon black, acetylene black, and carbon nanotubes. The binder is selected from any one or more of polyvinylidene fluoride and polytetrafluoroethylene.

[0028] The above-mentioned negative electrode is a lithium metal sheet with a diameter of 15.6 mm and a height of 0.45 mm.

[0029] Technologies not mentioned in the present invention shall refer to the prior art.

[0030] The present invention utilizes the unique chemical properties of phenyl isocyanate additives to form a crosslinked network through their self-polymerization reaction or with the polymer matrix. The introduction of phenyl isocyanate compounds not only optimizes the mechanical properties of the composite solid electrolyte but also significantly enhances the high-temperature stability and cycling stability of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Optical photograph of the polymer electrolyte membrane of Example 1.

[0032] Figure 2 Capacity retention graph of Example 1. The abscissa is the number of cycles, and the ordinate is the capacity retention rate. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with examples, but the content of the present invention is not limited to the following examples.

[0034] In each example, unless otherwise specified, the temperature is carried out at room temperature (20 - 25 °C); unless otherwise specified, the stirring speed is carried out at 150 r / min.

[0035] Example 1

[0036] In a glove box under an inert gas atmosphere: Weigh 0.5 g of poly(vinylidene fluoride - hexafluoropropylene) copolymer (produced by Beijing Innochem Technology Co., Ltd., with a specification of Mw ≈ 400000 and Mn ≈ 130000) and 0.5 g of lithium bis(trifluoromethanesulfonyl)imide, add them to 8.8 g of the organic solvent N,N-dimethylacetamide, stir at room temperature until completely dissolved, then add 0.2 g of the additive 3,5-bis(trifluoromethyl)phenyl isocyanate, and continue to stir for 6 h to obtain a uniform, viscous, transparent, and clear precursor solution; coat the precursor solution onto a polytetrafluoroethylene mold, heat it to 60 °C in a vacuum oven, and cure it for 12 hours to form a film. Cut it into a circular piece with a diameter of 16 mm using a tablet press to obtain a polymer solid electrolyte membrane with a thickness of 105 μm, and store it in the glove box for later use.

[0037] Preparation method of the positive electrode: Weigh 1 g of conductive additive carbon black (purchased from Dongguan Kelude Experimental Equipment Technology Co., Ltd., Super C45, MA-EN-CO-0003, powder conductivity 10-15 S / CM), 1 g of binder polyvinylidene fluoride (purchased from Dongguan Kelude Experimental Equipment Technology Co., Ltd., PVDF 900, MA-EN-BI-0009, purity > 99.5%), dissolve them in 30 g of organic solvent N-methylpyrrolidone, stir evenly, then weigh 8 g of active material lithium iron phosphate and add it to stir into a uniform slurry. The final slurry should just flow. Coat it on the aluminum foil, place it in a blast drying oven at 80 °C for 2 h, and then dry it in a vacuum oven at 110 °C for 12 h. Cut it into small round pieces with a diameter of 12 mm to obtain a positive electrode with a thickness of 60 μm.

[0038] The negative electrode is a lithium metal sheet with a diameter of 15.6 mm and a height of 0.45 mm.

[0039] Assembly of the battery: Prepare 2032 button batteries in an Ar-filled glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), and assemble a solid-state lithium battery using the above-prepared positive electrode, negative electrode, and polymer solid electrolyte membrane. The following are the assembly steps: positive electrode case - spring sheet - stainless steel gasket - positive electrode plate - polymer solid electrolyte membrane - negative lithium sheet - stainless steel gasket - negative electrode case.

[0040] Example 2

[0041] In a glove box with an inert gas atmosphere: Weigh 0.5 g of polyvinylidene fluoride-hexafluoropropylene copolymer (produced by Beijing Innochem Technology Co., Ltd., specification Mw≈400000, Mn≈130000), 0.5 g of lithium bis(trifluoromethanesulfonyl)imide, add them to 8.8 g of organic solvent dimethylacetamide, stir at room temperature until completely dissolved, then add 0.1 g of additive 4-(trifluoromethyl)phenyl isocyanate and 0.1 g of film-forming additive fluoroethylene carbonate, and continue to stir for 6 h to obtain a uniform, viscous, transparent, and clear precursor solution; coat the precursor solution on a polytetrafluoroethylene mold, heat it to 60 °C in a vacuum oven, and cure it for 12 hours to form a film. Cut it into round pieces with a diameter of 16 mm using a tablet press to obtain a polymer solid electrolyte membrane with a thickness of 105 μm, and store it in the glove box for later use.

[0042] Preparation method of the positive electrode: Weigh 1 g of conductive additive conductive carbon black (purchased from Dongguan Kelude Experimental Equipment Technology Co., Ltd., Super C45, MA-EN-CO-0003, powder conductivity 10 - 15 S / CM), 1 g of binder polyvinylidene fluoride (purchased from Dongguan Kelude Experimental Equipment Technology Co., Ltd., PVDF 900, MA-EN-BI-0009, purity > 99.5%), dissolve them in 30 g of organic solvent N-methylpyrrolidone, stir evenly, then weigh 8 g of active material lithium iron phosphate and add it to stir into a uniform slurry. The final slurry should just be able to flow. Scraping-coat it on the aluminum foil, place it in a blast drying oven at 80°C for 2 h, and then dry it in a vacuum oven at 110°C for 12 h. Cut it into small round pieces with a diameter of 12 mm to obtain a positive electrode with a thickness of 60 μm.

[0043] The negative electrode is a lithium metal sheet with a diameter of 15.6 mm and a height of 0.45 mm.

[0044] Assembling the battery: Prepare 2032 button batteries in an Ar-filled glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), and assemble the above positive electrode, negative electrode and solid electrolyte into a solid-state lithium battery. The following are the assembly steps: positive electrode case - spring piece - stainless steel gasket - positive electrode plate - polymer solid electrolyte membrane - negative lithium sheet - stainless steel gasket - negative electrode case.

[0045] Example 3

[0046] Prepare the solid-state battery polymer electrolyte and 2032 button batteries according to the preparation method described in Example 1, with the only difference being that the phenyl isocyanate is 4-(trifluoromethyl)phenyl isocyanate.

[0047] Example 4

[0048] Prepare the solid-state battery polymer electrolyte and 2032 button batteries according to the preparation method described in Example 1, with the only difference being that the phenyl isocyanate is 4-chloro-3-(trifluoromethyl)phenyl isocyanate.

[0049] Example 5

[0050] Prepare the solid-state battery polymer electrolyte and 2032 button batteries according to the preparation method described in Example 1, with the only difference being that the phenyl isocyanate is 4-acetylphenyl isocyanate.

[0051] Example 6

[0052] Prepare the solid-state battery polymer electrolyte and 2032 button batteries according to the preparation method described in Example 1, with the only difference being that the phenyl isocyanate is 2-(trifluoromethyl)phenyl isocyanate.

[0053] Example 7

[0054] The solid-state battery polymer electrolyte and 2032 button battery were prepared according to the preparation method described in Example 1, except that the phenyl isocyanate was 2-(trifluoromethoxy)phenyl isocyanate.

[0055] Example 8

[0056] The solid-state battery polymer electrolyte and 2032 button battery were prepared according to the preparation method described in Example 1, except that the phenyl isocyanate was 4-fluoro-3-methylphenyl isocyanate.

[0057] Example 9

[0058] The solid-state battery polymer electrolyte and 2032 button battery were prepared according to the preparation method described in Example 1, except that the phenyl isocyanate was 3,4,5-trimethoxyphenyl isocyanate.

[0059] Example 10

[0060] The solid-state battery polymer electrolyte and 2032 button battery were prepared according to the preparation method described in Example 2, except that the phenyl isocyanate was 0.01 g of 4-(trifluoromethyl)phenyl isocyanate.

[0061] Example 11

[0062] The solid-state battery polymer electrolyte and 2032 button battery were prepared according to the preparation method described in Example 2, except that the phenyl isocyanate was 0.02 g of 4-(trifluoromethyl)phenyl isocyanate.

[0063] Example 12

[0064] The solid-state battery polymer electrolyte and 2032 button battery were prepared according to the preparation method described in Example 2, except that the phenyl isocyanate was 0.05 g of 4-(trifluoromethyl)phenyl isocyanate.

[0065] Comparative Example 1

[0066] The solid-state battery polymer electrolyte and 2032 button battery were prepared according to the preparation method described in Example 2, except that the lithium salt was 0.5 g of lithium hexafluorophosphate.

[0067] Comparative Example 2

[0068] The solid-state battery polymer electrolyte and 2032 button battery were prepared according to the preparation method described in Example 2, except that there was no additive and the lithium salt was 0.5 g of lithium tetrafluoroborate.

[0069] Comparative Example 3

[0070] The solid-state battery polymer electrolyte and 2032 button battery were prepared according to the preparation method described in Example 2, except that there was no phenyl isocyanate and the lithium salt was 0.5 g of lithium hexafluorophosphate.

[0071] Comparative Example 4

[0072] Prepare a solid-state battery polymer electrolyte and a 2032 button battery according to the preparation method described in Example 1, except that phenyl isocyanate is toluene-2,4-diisocyanate.

[0073] Test Example

[0074] Cycling performance test: The 2032 button batteries prepared in Examples 1 to 12 and Comparative Examples 1 to 4 were formed at 0.1C for three cycles at room temperature and then charged and discharged at a constant current of 1C. The charge-discharge interval was 2.8 to 3.8V, and the cut-off current was 0.02A. After 100 cycles, the cycling performance of the lithium battery was evaluated. The room temperature cycling performance was calculated by the capacity retention rate of the following formula:

[0075] Capacity retention rate (%) = (discharge capacity of the 100th cycle / initial discharge capacity) × 100%;

[0076] High-temperature cycling performance test:

[0077] The 2032 button batteries prepared in Examples 1 to 12 and Comparative Examples 1 to 4 were stored at a high temperature of 50°C. After being formed at 0.1C for three cycles, they were charged to 3.8V at a constant current and constant voltage of 1C, the cut-off current was 0.02A, and then discharged to 2.8V at a constant current of 1C. After repeating the 1C charge / 1C discharge cycle 100 times, the cycling performance of the lithium battery was evaluated. The cycling performance was calculated by the capacity retention rate of the following formula.

[0078] Capacity retention rate (%) = (discharge capacity of the 100th cycle / initial discharge capacity) × 100%.

[0079] Rate performance test:

[0080] The 2032 button batteries prepared in Examples 1 to 12 and Comparative Examples 1 to 4 were placed at room temperature, and then charged and discharged cyclically 5 times at a constant current and constant voltage of 0.1C, 0.2C, 0.5C, 1C, 2C, and 5C in sequence. The charge-discharge interval was 2.8 to 3.8V, and the cut-off current was 0.02C. Then, finally, they were charged and discharged cyclically 50 times at a constant current and constant voltage of 1C in this interval to measure the high-rate cycling performance of the lithium battery. The high-rate cycling performance was calculated by the capacity retention rate of the following formula.

[0081] Capacity retention rate (%) = (discharge capacity of the 80th cycle / discharge capacity of the 15th cycle) × 100%.

[0082] The test results of the cycling performance, high-temperature cycling performance, and rate cycling performance are shown in Table 1.

[0083] Table 1 Test results of the cycle performance, high-temperature cycle performance, and rate cycle performance of 2032 button batteries prepared in Examples 1 to 13 and Comparative Examples 1 to 3

[0084] Normal temperature cycle performance (%) High temperature cycle performance (%) Rate performance (%) Example 1 94 92.3 95.5 Example 2 98.2 96.3 98.5 Example 3 91.5 90.6 92.6 Example 4 93.4 92.7 94.8 Example 5 94.9 93.1 94.2 Example 6 90.3 89.2 90.9 Example 7 95.0 93.7 96.1 Example 8 93.2 94.3 97.4 Example 9 95.2 97.8 99.4 Example 10 96.7 94.1 97.6 Example 11 97.6 95.3 97.8 Example 12 97.9 96 98.2 Comparative Example 1 93.5 91.7 94.4 Comparative Example 2 30.5 9.8 35.0 Comparative Example 3 46.2 33.5 40.6 Comparative Example 4 80.8 65.5 82.4

[0085] As can be seen from the results in Table 1, phenyl isocyanate compounds are effective polymer solid electrolyte additives for lithium batteries. Phenyl isocyanate compounds can stabilize the electrolyte and have high reactivity and solubility, which improves the dissolution of electrolyte (lithium) salts in the lithium-ion battery electrolyte. At the same time, phenyl isocyanate compounds with alkyl and methoxy groups have higher polarity and are more likely to form coordination bonds with electrolyte salts (such as PF6 - , TFSI - ), so they have a better stabilizing effect on lithium salts and also show more stable cycle performance for lithium batteries. This additive significantly enhances the high-temperature performance and cycle performance of the polymer solid electrolyte, increases the cycle life of the lithium-ion battery, and obtains a higher discharge capacity at high carbon rates. In addition, as phenyl isocyanate compounds can also stabilize electrolytes other than lithium bis(trifluoromethanesulfonyl)imide, such as lithium hexafluorophosphate and lithium tetrafluoroborate, improving battery performance.

[0086] Finally, it should be pointed out that the above examples are only used to illustrate the technical solutions of the present invention and do not limit the protection scope of the present invention. Although the present invention has been explained in detail by referring to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence of the technical solutions of the present invention.

Claims

1. Use of phenyl isocyanate, characterized in that, A functional additive used as a polymer electrolyte for a solid-state battery, and the addition amount of phenyl isocyanate is 0.5 to 5 wt% of the mass of the polymer electrolyte for the solid-state battery; the structural formula of phenyl isocyanate is: Wherein, R1 to R5 are independently a hydrogen atom, a halogen atom, a methoxy group, an acetyl group or an alkyl group containing 1 to 6 carbon atoms.

2. The use of phenyl isocyanate according to claim 1, wherein The phenyl isocyanate is at least one of 4-(trifluoromethyl)phenyl isocyanate, 4-chloro-3-trifluoromethylphenyl isocyanate, 3,5-bis(trifluoromethyl)phenyl isocyanate, 4-acetylphenyl isocyanate, 2-chloro-4-(trifluoromethyl)phenyl isocyanate, 2-(trifluoromethyl)phenyl isocyanate, 2-(trifluoromethoxy)phenyl isocyanate, 4-fluoro-3-methylphenyl isocyanate, 2-fluoro-5-methylphenyl isocyanate, 3,4-dimethylphenyl isocyanate or 3,4,5-trimethoxyphenyl isocyanate.

3. The use of phenyl isocyanate according to claim 2, characterized in that, The phenyl isocyanate is 3,4,5-trimethoxyphenyl isocyanate, 2-(trifluoromethoxy)phenyl isocyanate or 4-acetylphenyl isocyanate.

4. A solid-state battery polymer electrolyte membrane, characterized in that, Its raw materials include: 0.5 to 5% of the phenyl isocyanate according to any one of claims 1 to 3, 0.5 to 5% of a film-forming additive, 3 to 10% of a polymer matrix, 70 to 90% of an organic solvent, and 3 to 10% of a lithium salt, and the foregoing percentages are all mass percentages; The polymer matrix is at least one of polyethylene oxide - polypropylene oxide, polyethylene oxide - polymethyl methacrylate, polyvinylidene fluoride - hexafluoropropylene copolymer or polyvinylidene fluoride - chlorotrifluoroethylene copolymer.

5. The solid-state battery polymer electrolyte membrane according to claim 4, characterized in that, The film-forming additive is at least one of vinylene carbonate, 1,3-propane sultone, 1,4-butane sultone, acrylic lactone, ethylene carbonate ethyl ester, fluorinated ethylene carbonate, lithium difluorophosphate, lithium bis(oxalato)borate or lithium bis(trifluoromethanesulfonyl)imide.

6. The solid-state battery polymer electrolyte membrane according to claim 4 or 5, characterized in that, The lithium salt is at least one of lithium hexafluorophosphate, lithium perchlorate, lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium trifluoromethanesulfonate or lithium difluoro(oxalato)borate.

7. The solid-state battery polymer electrolyte membrane according to claim 4 or 5, characterized in that, The organic solvent is at least one of adiponitrile, tetrahydrofuran, diethyl sulfite, dimethylacetamide, γ-butyrolactone, acetone, ethylene carbonate, methyl acetate, ethyl acetate, propylene carbonate acetone, butylene carbonate, 1-methyl-2-pyrrolidone, dimethyl carbonate or ethylene carbonate.

8. A method for preparing a solid-state battery polymer electrolyte membrane according to any one of claims 4-7, characterized in that, It includes the following steps: uniformly mixing the polymer matrix, the organic solvent and the lithium salt to obtain a mixed solution; then adding the phenyl isocyanate and the film-forming additive into the mixed solution, and stirring for 6 to 12 h to obtain a precursor solution; then coating the precursor solution on a polytetrafluoroethylene mold of a flat plate, and drying at 40 to 80 °C for 8 to 14 hours to obtain a polymer solid electrolyte membrane.

9. A all-solid-state lithium-ion battery, comprising the solid-state battery polymer electrolyte membrane according to any one of claims 4-7, characterized in that, Its structure includes a positive electrode case - a spring piece - a stainless steel gasket - a positive electrode - a polymer solid electrolyte membrane - a negative electrode - a stainless steel gasket - a negative electrode case connected in sequence.

10. The all-solid-state lithium-ion battery according to claim 9, characterized in that, The active material of the positive electrode is at least one of lithium cobaltate, lithium nickelate, lithium iron phosphate or lithium nickel cobalt manganate; the active material of the negative electrode is at least one of metallic lithium, metallic lithium alloy, graphite, hard carbon, carbon-silicon composite material, lithium titanate or lithium titanium oxide.

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