A method for preparing a solid-state electrolyte from isocyanate in situ and application in a solid-state battery in situ

Abstract

The application discloses a method for preparing a solid-state electrolyte by in-situ self-polymerization of isocyanate and application in a solid-state battery. The preparation method comprises the following steps: a) mixing isocyanate monomers, a lithium salt, an initiator and a solvent to obtain a prepolymer solution; b) injecting the prepolymer solution obtained in step a) into a battery for infiltration, and then polymerizing to obtain a solid-state electrolyte and a solid-state battery. The application provides a novel in-situ solidification electrolyte material, the isocyanate monomers are in-situ self-polymerized in the battery to obtain a solid-state electrolyte. Since the in-situ polymerization method is adopted, the contact between the electrode and the electrolyte is closer, the interface impedance between the electrode and the electrolyte is reduced, and meanwhile, the electrolyte contains a large amount of isocyanurate carbon-nitrogen cyclic structures after solidification, and has excellent thermal stability, acid and alkali resistance, flame resistance and redox resistance. The application also discloses a solid-state lithium battery prepared by using the in-situ polymerization electrolyte.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polymer lithium battery and lithium-sulfur battery, more particularly, to a solid-state electrolyte, a preparation method thereof and application thereof in a solid-state battery. BACKGROUND

[0002] Currently, a large number of organic carbonate liquid electrolytes are contained in large-scale commercialized lithium secondary batteries. Due to the low boiling point and flammability of the organic carbonate liquid electrolytes, deformation or even electrolyte leakage may occur when the lithium secondary batteries are squeezed or collided during use, which may cause the lithium secondary batteries to catch fire or explode, thus having a significant safety hazard. Polymer electrolytes have become a research hotspot in recent years due to small interface impedance and flame retardancy. However, the polymer electrolytes have not entered the large-scale production stage due to the complex battery preparation process.

[0003] In order to improve the preparation process of the polymer solid-state lithium battery and improve the production efficiency, researchers have proposed a method for preparing a solid-state battery based on in-situ solidification. For example, a Chinese patent with the publication number CN105914405A discloses a method for preparing a full-solid-state polymer electrolyte by in-situ ring-opening polymerization of an epoxy compound and application thereof in a full-solid-state lithium battery. The method uses liquid epoxy-based compounds, lithium salts and battery additives as precursors, which are injected into the inside of a battery. Then, under heating conditions, the precursors are in-situ ring-opening solidified into an integrated full-solid-state polymer battery. A Chinese patent with the publication number CN108493486A discloses a method for preparing a solid-state battery by in-situ polymerization. The method uses an acrylate, an initiator and an electrolyte, which are injected into the inside of a battery. Then, under heating conditions, the precursors are in-situ polymerized into an integrated gel polymer battery. A Chinese patent with the publication number CN111533851A discloses a method for preparing a polymer electrolyte and application thereof in a full-solid-state battery. The method uses a small molecule containing a double bond, ethylene glycol acrylate and an initiator, which are mixed and injected into the interface of a solid-state battery. Then, under heating conditions, the precursors are polymerized to form an electrode-electrolyte integrated full-solid-state battery.

[0004] The polymer backbone structure used in the traditional in-situ polymerization method is generally ester and ether polymer, which has low flame retardancy. During the storage of the battery, lithium salt reacts with trace amount of water to produce HF and other impurities, which leads to the dissolution of transition metal in the electrode material, the destruction of SEI film and the deterioration of battery performance. Isocyanate has been applied in lithium battery system due to its good water removal property, electrode material surface film forming property, copolymer structure diversity and other characteristics. Among them, the patent with publication number CN111129586A uses isocyanate as an additive, and the amount of isocyanate added is 0.5-1%. During the charging and discharging process, isocyanate is electropolymerized into a film on the surface of the positive electrode material, which inhibits the corrosion of the positive electrode material by hydrofluoric acid in the electrolyte and improves the cycle stability of the high-voltage material. The patent with publication number CN109244543A uses isocyanate homopolymer or copolymer as an additive to inhibit the conversion of water into free acid and the acidity caused by lithium salt itself, and at the same time, it does not produce precipitates that affect the performance of the battery, thereby improving the high-temperature resistance of the battery. The patent with publication number CN111540956A discloses an in-situ solidified electrode micro-interface treatment process, which dissolves isocyanate and polypropylene glycol in an electrolyte and injects it into the interior of a battery to electropolymerize into an integrated battery, thereby reducing the electrode-electrolyte interface impedance. In summary, isocyanate is often used as an additive or copolymerized with a group containing active hydrogen to form a polyurethane as a key material for lithium secondary batteries, but the application of in-situ solidified electrolyte based on isocyanate self-polymerization in batteries has not been reported. SUMMARY

[0005] The present application provides a novel polymer material for in-situ solid-state electrolyte, characterized by using isocyanate monomer and other substances as precursors, directly injecting them between the positive and negative electrodes of a battery, and self-polymerizing into a solid-state electrolyte in-situ to obtain a solid-state battery. The polymer solid-state electrolyte uses an in-situ solidification method to improve the contact between the electrode and the electrolyte and reduce the interface impedance between the electrode and the electrolyte. At the same time, the electrolyte contains a large amount of isocyanuric acid ester carbon-nitrogen ring structure after solidification, which has excellent thermal stability, acid and alkali resistance, flame retardancy and redox resistance, greatly improving the cycle performance and safety of the battery.

[0006] The present application provides a preparation method of an in-situ self-polymerized solid-state electrolyte from isocyanate, comprising the following steps:

[0007] a) mixing isocyanate monomer, lithium salt, initiator and solvent to obtain a monomer pre-polymer solution;

[0008] b) injecting the monomer pre-polymer solution obtained in step a) into the interior of a battery for infiltration, and then polymerizing to obtain an in-situ solidified electrolyte.

[0009] Preferably, the isocyanate monomer in step a) is selected from toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, biuret triisocyanate, lysine diisocyanate, xylylene diisocyanate, tetramethylxylene diisocyanate, 1,5-naphthalene diisocyanate, 3,3'-dimethyl-4,4'-diphenyl diisocyanate, 1,4-cyclohexyl diisocyanate, trimethyl-1,6-hexamethylene diisocyanate, tetramethylxylylene diisocyanate, methylcyclohexyl diisocyanate, decamethylene diisocyanate, 1,12-dodecane diisocyanate, 2,2,4-trimethylcyclohexyl diisocyanate, triphenylmethane triisocyanate, 4,4',4"-triisocyanatotriphenylphosphonium, cyclohexane dimethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, 4,4'-diphenyl diisocyanate, norbornane diisocyanate, p-phenylene diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 3,3'-dimethoxybiphenyl-4,4'-diisocyanate, 2-methylpentane diisocyanate, 4,4'-diphenyl ether diisocyanate, 4-methyldiphenylmethane-3,4-diisocyanate, 2,4'-diphenyl sulfide diisocyanate, diethylbenzene diisocyanate, 4,4'-diphenylethane diisocyanate, dimethylbenzyl diisocyanate, isopropylidene bis(4-isocyanatocyclohexane), and diisocyanate derivatives (such as liquefied MDI, TDI dimer, TDI trimer, TDI-TMP adduct, TDI-HDI mixed multimer, HDI adduct, HDI dimer, HDI trimer, HDI biuret, HDI allophanate, IPDI trimer, H6XDI trimer, XDI adduct, H6XDI adduct, IPDI adduct, HDI prepolymer), triphenylmethane-4,4'-4"-triisocyanate, tri(4-phenyl isocyanate)thiophosphonium, dimethyltriphenylmethane tetraisocyanate, p-toluenesulfonylisocyanate (PTSI), pentafluorophenyl isocyanate (PFPI), C-MDI polyisocyanate, and dimers, trimers, and multimers of the above isocyanates.

[0010] Preferably, the lithium salt in step a) is selected from one or more of lithium bistrifluoromethylsulfonylimide, lithium trifluoromethylsulfonate, lithium bisoxalateborate, lithium difluorooxalateborate, lithium bisfluorosulfonylimide, lithium hexafluoroarsenate, lithium tetrafluoroborate, lithium perchlorate, lithium difluorophosphate, lithium hexafluorophosphate.

[0011] Preferably, the initiator in step a) is selected from one or more of trialkyl phosphine, tertiary amine, quaternary ammonium salt, nitrogen family element compound, organosilicon phosphorus heteroatomic compound, organometallic compound, and basic carboxylic acid salt, such as triethyl phosphine, pyridine, dimethyl phenyl phosphine, tris(dimethylaminopropyl)hexahydrotriazine, 2,4,6-tris(dimethylaminomethyl)phenol, trimethyl-N-2-hydroxypropyl hexanoic acid, octanoic acid tetramethyl ammonium salt, N-hydroxyalkyl quaternary ammonium base, potassium acetate, triphenyl phosphine, tri-n-butyl phosphine, lithium acetate, butyl lithium, cesium fluoride, tributyl tin oxide, tetrabutyl titanate, tetrabutyl zirconate, trialkyl tin alkoxide, dialkyl tin oxide, N,N-dimethyl cyclohexyl amine, bis(2-dimethylaminoethyl) ether, triethylenediamine, triethylamine, N,N,N',N'-tetramethyl alkylene diamine, N,N-dimethyl benzyl amine, N,N-dimethyl butyl amine, N,N-dimethyl hexadecyl amine, N-ethyl morpholine, N-methyl morpholine, N,N-diethyl piperazine, N,N-diethyl-2-methyl piperazine, N,N'-bis(α-hydroxypropyl)-2-methyl piperazine, triethanolamine, N,N-dimethyl ethanolamine, N,N-dimethyl pyridine, (dimethylaminoethyl) ether, N-methyl ethylenediamine, dimethyl formamide, triethylene ethylenediamine, methyl diglycol amine, and triethylenediamine, hexamethyl disilazane, lithium bis(trifluoromethyl sulfonyl imide), lithium bis(fluorosulfonyl imide), potassium carboxylate.

[0012] Preferably, the solvent in step a) is selected from one or more of vinyl carbonate, fluorinated vinyl carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, butylene carbonate, methyl propyl carbonate, methyl formate, ethyl formate, propyl formate, butyl formate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, δ-valerolactone, tetrahydrofuran, 2-methyl tetrahydrofuran, 4-methyl-1,3-dioxolane, 2-methyl-1,3-dioxolane, ethylene glycol dimethyl ether, and 1,3 dioxolane, sulfolane, dimethyl sulfoxide.

[0013] Preferably, the mass ratio of the isocyanate monomer, lithium salt, initiator, and solvent in step a) is (5-95):(5-30):(0-5):(0-60).

[0014] Preferably, the time of the infiltration in step b) is 2h-24h.

[0015] Preferably, the polymerization in step b) is performed under heating; the temperature of the polymerization is 20℃-130℃, and the time is 5h-120h.

[0016] The application also provides a solid-state battery, comprising a positive electrode, a negative electrode, a separator and an in-situ solid-state electrolyte, wherein the in-situ solid-state electrolyte is the solid-state electrolyte prepared by in-situ self-polymerization of isocyanate monomers.

[0017] The positive electrode active material is one or more of lithium cobaltate, lithium manganate, lithium nickel manganate, ternary lithium nickel cobalt manganate, lithium nickel cobalt aluminate, lithium nickel cobalt manganese aluminate, lithium manganese iron phosphate, lithium iron phosphate, sulfur, lithium sulfide; the negative electrode material is one of metal lithium, metal lithium alloy, graphite, hard carbon, molybdenum disulfide, lithium titanate, graphene, silicon, silicon carbon, silicon oxygen, silicon oxygen carbon negative electrode; the separator is one or more of commercial PP, PE, PI, cellulose membrane, PET porous membrane and ceramic coating membrane.

[0018] The application provides a preparation method of an in-situ self-polymerized solid-state electrolyte from isocyanate and application thereof in a solid-state battery; the preparation method comprises the following steps: a) mixing isocyanate monomers, lithium salt, initiator and solvent to obtain a monomer prepolymer solution; b) injecting the monomer prepolymer solution obtained in step a) into the inside of a battery for infiltration, and then polymerizing to obtain a solid-state electrolyte. The application provides a novel polymer material for solid-state electrolyte, which initiates self-polymerization of isocyanate monomers in a battery to form a solid-state electrolyte. The polymer solid-state electrolyte adopts an in-situ solidification mode, improves the contact between the electrode and the electrolyte, and reduces the interfacial impedance between the electrode and the electrolyte. Meanwhile, the electrolyte contains a large amount of isocyanurate carbon-nitrogen ring structure after solidification, has excellent thermal stability, acid and alkali resistance, flame resistance and redox resistance, and greatly improves the cycle performance and safety of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The AC impedance diagram of the button cell of Example 1 and Comparative Example 1 is shown in Figure 1;

[0020] Figure 2 The first cycle charge-discharge voltage-specific capacity curve of the button cell of Example 1 and Comparative Example 1 is shown in Figure 2;

[0021] Figure 3 The specific capacity-cycle number and coulombic efficiency-cycle number change diagram of the button cell of Example 1 and Comparative Example 1 is shown in Figure 3;

[0022] Figure 4 The linear voltammetry scan curve of the battery device of Example 1 and Comparative Example 1 is shown in Figure 4;

[0023] Figure 5 The voltage-time curve of the 10 Ah soft package battery in Example 1 during the needle pricking process is shown in Figure 5;

[0024] Figure 6 The battery temperature-time curve of the 10 Ah soft package battery in Example 1 during the needle pricking process is shown in Figure 6;

[0025] Figure 7 Voltage-time curve of the 10 Ah pouch cell during the needling process in Comparative Example 1;

[0026] Figure 8 Cell temperature-time curve of the 10 Ah pouch cell during the needling process in Comparative Example 1. DETAILED DESCRIPTION

[0027] The technical solutions of the present application will be described clearly and completely below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0028] The present application provides a preparation method of a solid-state electrolyte self-polymerized in situ from isocyanate, comprising the following steps:

[0029] a) mixing isocyanate monomer, lithium salt, initiator and solvent to obtain a monomer prepolymer solution;

[0030] b) injecting the monomer prepolymer solution obtained in step a) into the inside of a battery for infiltration, and then polymerizing to obtain a solid-state electrolyte.

[0031] The present application first mixes isocyanate monomer, lithium salt, initiator and solvent to obtain a monomer prepolymer solution. In the present application, the isocyanate monomer is preferably selected from toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), polymeric diphenylmethane diisocyanate (PAPI), 4,4'-dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), biuret triisocyanate generated by the reaction of HDI with water, lysine diisocyanate (LDI), xylylene diisocyanate (XDI), tetramethyl xylene diisocyanate (TMXDI), 1,5-naphthalene diisocyanate (NDI), 3,3'-dimethyl-4,4'-diphenyl diisocyanate (TODI), 2,2,4-trimethylcyclohexyl diisocyanate (TMDI), triphenylmethane triisocyanate (TTI), 4,4',4"-trisphenyl thiophosphoric acid triisocyanate (TPTI), cyclohexane dimethylene diisocyanate (H6XDI), 4,4'-dicyclohexylmethane diisocyanate (H 12one or more of 4,4'-diphenylmethane diisocyanate (MDI), polymethylene polyphenyl polyisocyanate (PAPI), 4,4'-diphenyl diisocyanate (DBDI), norbornane diisocyanate (NDI), p-phenylene diisocyanate (PPDI), 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate (DMMDI), p-toluenesulfonyl isocyanate (PTSI), pentafluorophenyl isocyanate (PFPI), C-MDI polyisocyanate and tri-mer of diisocyanates (such as MDI trimer, trimer of HDI), more preferably one or more of IPDI, MDI, TDI, HDI, MDI trimer, PPDI, DMMDI, PTSI, PFPI, LDI, TODI and TTI. The source of the isocyanate monomer is not particularly limited in the present application, and commercially available or self-made products of the above diisocyanates, triisocyanates and self-polymerization products (including dimers, trimers and polymers) known to those skilled in the art can be used.

[0032] In the present application, the lithium salt is preferably one or more of lithium bistrifluoromethanesulfonimide (LiTFSI), lithium trifluoromethanesulfonate (LiCF3SO3), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(fluorosulfonyl)imide (LiFSI), lithium hexafluoroarsenate (LiAsF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluorophosphate (LiPF6), more preferably LiDFOB, LiTFSI or LiPF6. The source of the lithium salt is not particularly limited in the present application, and commercially available or self-made products known to those skilled in the art can be used.

[0033] In the present application, the initiator is selected from one or more of trialkyl phosphine, tertiary amine, quaternary ammonium salt, nitrogen group element compound, organosilicon phosphorus heteroatomic compound, organometallic compound, and basic carboxylic acid salt, etc., such as triethyl phosphine, pyridine, dimethyl phenyl phosphine, tris(dimethylaminopropyl)hexahydrotriazine, 2,4,6-tris(dimethylaminomethyl)phenol, trimethyl-N-2-hydroxypropyl hexanoic acid, tetramethyl ammonium salt of octanoic acid, N-hydroxyalkyl quaternary ammonium base, potassium acetate, triphenyl phosphine, tri-n-butyl phosphine, lithium acetate, butyl lithium, cesium fluoride, tributyl tin oxide, tetrabutyl titanate, tetrabutyl zirconate, trialkyl tin alkoxide, dialkyl tin oxide, N,N-dimethyl cyclohexyl amine, bis(2-dimethylamino ethyl) ether, triethylene diamine, triethyl amine, N,N,N',N'-tetramethyl alkylene diamine, N,N-dimethyl benzyl amine, N,N-dimethyl butyl amine, N,N-dimethyl hexadecyl amine, N-ethyl morpholine, N-methyl morpholine, N,N-diethyl piperazine, N,N-diethyl-2-methyl piperazine, N,N'-bis(alpha-hydroxypropyl)-2-methyl piperazine, triethanol amine, N,N-dimethyl ethanol amine, N,N-dimethyl pyridine, (dimethylamino ethyl) ether, N-methyl ethylene diamine, dimethyl formamide, triethylene ethylene diamine, methyl diethylene glycol amine and triethylene diamine, hexamethyl disilazane, lithium bis(trifluoromethyl sulfonyl imide), lithium bis(fluorosulfonyl imide), potassium carboxylate, more preferably tributyl tin oxide, lithium acetate or tri-n-butyl phosphine. The present application does not have special limitation on the source of the initiator, and the commercially available products of the above-mentioned triethyl phosphine, pyridine, dimethyl phenyl phosphine, tris(dimethylaminopropyl)hexahydrotriazine, 2,4,6-tris(dimethylaminomethyl)phenol, trimethyl-N-2-hydroxypropyl hexanoic acid, tetramethyl ammonium salt of octanoic acid, N-hydroxyalkyl quaternary ammonium base, potassium acetate, triphenyl phosphine, tri-n-butyl phosphine, lithium acetate, butyl lithium, cesium fluoride, tributyl tin oxide, tetrabutyl titanate, tetrabutyl zirconate, trialkyl tin alkoxide, dialkyl tin oxide, N,N-dimethyl cyclohexyl amine, bis(2-dimethylamino ethyl) ether, triethylene diamine, triethyl amine, N,N,N',N'-tetramethyl alkylene diamine, N,N-dimethyl benzyl amine, N,N-dimethyl butyl amine, N,N-dimethyl hexadecyl amine, N-ethyl morpholine, N-methyl morpholine, N,N-diethyl piperazine, N,N-diethyl-2-methyl piperazine, N,N'-bis(alpha-hydroxypropyl)-2-methyl piperazine, triethanol amine, N,N-dimethyl ethanol amine, N,N-dimethyl pyridine, (dimethylamino ethyl) ether, N-methyl ethylene diamine, dimethyl formamide, triethylene ethylene diamine, methyl diethylene glycol amine and triethylene diamine, hexamethyl disilazane, lithium bis(trifluoromethyl sulfonyl imide), lithium bis(fluorosulfonyl imide), potassium carboxylate, which are well known to those skilled in the art, can be used.

[0034] In the present application, the solvent is preferably selected from one or more of ethylene carbonate (EC), fluoroethylene carbonate (FEC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), ethylene glycol dimethyl ether (DME) and 1,3 dioxolane (DOL), butylene carbonate, methylpropyl carbonate, methyl formate, ethyl formate, propyl formate, butyl formate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, δ-valerolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 2-methyl-1,3-dioxolane, sulfolane, dimethyl sulfoxide, more preferably two or three of DMC, DEC, EC, DOL and DME. The present application has no special limitation on the source of the solvent, and any commercially available ethylene carbonate (EC), fluoroethylene carbonate (FEC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), ethylene glycol dimethyl ether (DME) and 1,3 dioxolane (DOL), butylene carbonate, methylpropyl carbonate, methyl formate, ethyl formate, propyl formate, butyl formate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, δ-valerolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 2-methyl-1,3-dioxolane, sulfolane, dimethyl sulfoxide known to those skilled in the art can be used.

[0035] In the present application, the mass ratio of the isocyanate monomer, lithium salt, initiator and solvent is preferably (5-95):(5-30):(0-5):(0-60). In the preferred embodiment of the present application, the ratio of the isocyanate monomer, lithium salt, initiator and solvent is preferably (0.5g-1g):(0.00015-0.00028g):0.02g:(1-1.4g).

[0036] In the present application, the in-situ polymerization of the isocyanate monomer to prepare the solid-state electrolyte is adapted to the electrolyte formulation and commercial electrolyte known to those skilled in the art.

[0037] In the present application, the mixing process is preferably carried out in a glove box filled with inert gas; either manual stirring or mechanical stirring known to those skilled in the art can be used, with the aim of mixing the components uniformly. In the present application, the inert gas is preferably argon.

[0038] After obtaining the monomer prepolymer solution, the obtained prepolymer solution is injected into the battery for infiltration, and then polymerized to obtain a solid-state electrolyte. In the present application, the battery is preferably obtained by assembling a battery pack including positive and negative electrode sheets in a manner known to those skilled in the art; in the preferred embodiment of the present application, the battery is a button cell and a soft pack cell. In the present application, the assembly process is preferably carried out in a glove box filled with inert gas; the inert gas is preferably argon. In the preferred embodiment of the present application, the battery is assembled with lithium cobaltate, lithium manganate, ternary lithium nickel cobalt manganate, lithium iron phosphate as the positive electrode, and metal lithium, graphite as the negative electrode.

[0039] The present application does not have special restrictions on the temperature of the infiltration, and room temperature known to those skilled in the art can be used; the time of the infiltration is preferably 2h-24h, more preferably 4h.

[0040] In the present application, the polymerization process is preferably carried out under heating conditions to initiate in-situ self-polymerization of isocyanate monomers; the polymerization temperature is preferably 20℃-130℃, more preferably 50℃-80℃; the polymerization time is preferably 5h-120h, more preferably 8h-24h.

[0041] The preparation method provided by the present application uses in-situ self-polymerization of isocyanate monomers to obtain a solid-state electrolyte. A large amount of isocyanate will react with trace amounts of water remaining in the solvent and lithium salt at the initial stage of polymerization, inhibiting the conversion of water into free acid, and also inhibiting the acidity caused by the lithium salt itself.

[0042] The present application also provides a solid-state battery, comprising a positive electrode, a negative electrode, a separator and an in-situ solid-state electrolyte, wherein the in-situ solid-state electrolyte is the solid-state electrolyte prepared by in-situ self-polymerization of isocyanate monomers as described above; the preparation method of the solid-state battery comprises the following steps:

[0043] After the polymer electrolyte monomer prepolymer solution is injected between the positive and negative electrode sheets of the assembled battery and solidified, a solid-state battery is obtained; the polymer electrolyte monomer prepolymer solution is the prepolymer solution obtained in the above technical solution.

[0044] In the present application, the preparation method of the solid-state battery is consistent with the preparation method of the solid-state electrolyte described in the above technical solution as a whole, and can be used as a specific application of the preparation method of the solid-state electrolyte described in the above technical solution. In the present application, the solid-state electrolyte described in the above technical solution contains a large amount of isocyanuric acid ester carbon-nitrogen ring structure (formed after self-polymerization), has excellent thermal stability, acid and alkali resistance, flame resistance, and redox resistance, and the in-situ solid-state battery using the solid-state electrolyte has good cycle performance and safety.

[0045] The application provides a preparation method of a solid-state electrolyte prepared by in-situ self-polymerization of isocyanate and application in a solid-state battery; the preparation method comprises the following steps: a) mixing isocyanate monomers, a lithium salt, an initiator and a solvent to obtain a prepolymer solution; b) injecting the prepolymer solution obtained in step a) into a battery for infiltration, and then polymerizing to obtain a solid-state electrolyte. The application provides a novel polymer material for a solid-state electrolyte, the isocyanate monomers are used to initiate self-polymerization in the battery to form a solid-state electrolyte, the polymer solid-state electrolyte adopts an in-situ solidification mode, improves the contact between the electrode and the electrolyte, and reduces the interface impedance between the electrode and the electrolyte; after solidification, the electrolyte contains a large amount of isocyanurate carbon-nitrogen ring structures, and has excellent thermal stability, acid and alkali resistance, flame resistance and redox resistance, and the in-situ solidified battery using the solid-state electrolyte has good cycle performance and safety.

[0046] In order to further illustrate the application, the following examples are used for detailed description. The raw materials used in the following examples of the application are all commercially available.

[0047] Example 1

[0048] (1) 1g of IPDI, 0.02g of tributyltin oxide, 1mL of 1mol / L LiDFOB (DMC:DEC:EC=1:1:1, volume ratio) are mixed uniformly in an argon-filled glove box to obtain a prepolymer solution in a flowing state.

[0049] (2) In an argon-filled glove box, LiCo 0.1 Ni 0.8 Mn 0.1 O2 is used as a positive electrode, metal lithium is used as a negative electrode, and a commercial Al2O3 / PE porous separator is used to assemble a button cell, and then the polymer electrolyte prepolymer prepared in step (1) is used as an electrolyte, after assembly, the button cell is infiltrated at room temperature for 4h, and then solidified at 80℃ for 24h to obtain a solid-state lithium battery prepared by in-situ polymerization.

[0050] (3) In an argon-filled glove box, a stainless steel sheet is used as a positive electrode, metal lithium is used as a negative electrode, and a commercial Al2O3 / PE porous separator is used to assemble a button cell, and then the polymer electrolyte prepolymer prepared in step (1) is used as an electrolyte, after assembly, the button cell is infiltrated at room temperature for 4h, and then solidified at 80℃ for 24h to obtain a solid-state device prepared by in-situ polymerization.

[0051] (4) In an argon-filled glove box, LiCo 0.1 Ni 0.8 Mn 0.1O2 as the positive electrode, metal lithium and copper foil composite belt as the negative electrode, and commercial Al2O3 / PE porous separator to assemble a 10 Ah soft package battery, using the polymer electrolyte prepolymer prepared in step (1) as the electrolyte, the energy density of the assembled soft package battery is 350 Wh / kg, after assembly, immerse at room temperature for 4 h, and solidify at 80℃ for 24 h, to obtain a solid-state lithium battery in situ polymerized.

[0052] Further, the lithium battery prepared in step (2) is subjected to alternating current impedance test, the results are shown in Figure 1 ; 0.1C charge-discharge test, the voltage range is 2.75-4.2V, the results are shown in Table 1, the first circle charge-discharge curve is shown in Figure 1 , and the cycle-coulombic efficiency is shown in Figure 2 ; the in-situ solid-state device prepared in step (3) is subjected to electrochemical window test, the results are shown in Figure 3 ; the soft package battery prepared in step (4) is subjected to full state needle test, the needle test results are shown in Table 1, the voltage-time curve during the needle test is shown in Figure 5 , and the battery temperature change during the battery needle test is shown in Figure 6 .

[0053] Comparative Example 1

[0054] (1) In an argon-filled glove box, LiCo 0.1 Ni 0.8 Mn 0.1 O2 as the positive electrode, metal lithium as the negative electrode, commercial Al2O3 / PE porous separator, 1 mol / L LiDFOB (DMC:DEC:EC=1:1:1, volume ratio) as the electrolyte to assemble a button cell, after assembly, immerse at room temperature for 4 h to obtain a button lithium battery.

[0055] (2) In an argon-filled glove box, stainless steel sheet as the positive electrode, metal lithium as the negative electrode, commercial Al2O3 / PE porous separator, 1 mol / L LiDFOB (DMC:DEC:EC=1:1:1, volume ratio) as the electrolyte to assemble a button cell, after assembly, immerse at room temperature for 4 h to obtain a button cell test device.

[0056] (3) In an argon-filled glove box, LiCo 0.1 Ni 0.8 Mn 0.1 O2 as the positive electrode, metal lithium and copper foil composite belt as the negative electrode, commercial Al2O3 / PE porous separator, 1 mol / L LiDFOB (DMC:DEC:EC=1:1:1, volume ratio) as the electrolyte to assemble a 10 Ah soft package battery, the energy density of the assembled soft package battery is 350 Wh / kg, after assembly, immerse at room temperature for 4 h to obtain a soft package lithium battery.

[0057] Further, the lithium battery prepared in step (1) was subjected to AC impedance test, and the results are shown in Figure 1 ; 0.1C charge-discharge test was conducted at a voltage range of 2.75-4.2V, and the results are shown in Table 1, and the first cycle charge-discharge curve is shown in Figure 1 , and the cycle-coulombic efficiency is shown in Figure 2 ; the electrochemical window test was conducted on the button battery device prepared in step (2), and the results are shown in Figure 3 ; the full-state needle test was conducted on the soft package battery prepared in step (3), and the needle test results are shown in Table 1, the voltage-time curve during the needle test is shown in Figure 7 , and the battery temperature change during the needle test is shown in Figure 8 .

[0058] Table 1: Charge-discharge cycle and needle test results

[0059]

[0060]

[0061] Example 2

[0062] (1) 0.5 g MDI, 0.02 g lithium acetate, 1 mL 1 mol / L LiTFSI (DOL:DME = 1:1, volume ratio) were uniformly mixed in an argon-filled glove box to obtain a flowing pre-polymer solution.

[0063] (2) In an argon-filled glove box, LiCoO2 was used as the positive electrode, graphite was used as the negative electrode, and a commercial Al2O3 / PE porous separator was used to assemble a button battery. The polymer electrolyte pre-polymer prepared in step (1) was used as the electrolyte. After assembly, the button battery was immersed at room temperature for 4 h and cured at 80°C for 8 h to obtain a solid-state lithium battery polymerized in situ.

[0064] Further, the solid-state lithium battery prepared in Example 2 was subjected to 0.1C charge-discharge test at a voltage range of 2.75-4.2V, and the test results are shown in Table 2.

[0065] Comparative Example 2

[0066] (1) In an argon-filled glove box, LiCoO2 was used as the positive electrode, graphite was used as the negative electrode, a commercial Al2O3 / PE porous separator, and 1 mol / L LiTFSI (DOL:DME = 1:1, volume ratio) was used as the electrolyte to assemble a button battery. After assembly, the button battery was immersed at room temperature for 4 h to obtain a button lithium battery.

[0067] Further, the button lithium battery prepared in Comparative Example 2 was subjected to 0.1C charge-discharge test at a voltage range of 2.75-4.2V, and the test results are shown in Table 2.

[0068] Table 2 charge-discharge cycle results

[0069]

[0070] Example 3

[0071] (1) 0.8 g TDI, 0.2 g HDI, 0.02 g tri-n-butyl phosphine, 1 mL 1 mol / L LiPF6 (EMC: EC = 1:1, volume ratio) were mixed uniformly in an argon-filled glove box to obtain a prepolymer solution in a flowable state.

[0072] (2) In an argon-filled glove box, a button cell was assembled using LiMn2O4 as the positive electrode, graphite as the negative electrode, and a commercial Al2O3 / PE porous separator, and the polymer electrolyte prepolymer prepared in step (1) was used as the electrolyte. After assembly, the button lithium cell was immersed at room temperature for 4 h and cured at 50°C for 24 h to obtain a solid-state lithium battery polymerized in situ.

[0073] Further, the solid-state lithium battery prepared in Example 3 was subjected to 0.1C charge-discharge testing, and the voltage range was 2.75-4V. The test results are shown in Table 3.

[0074] Comparative Example 3

[0075] (1) In an argon-filled glove box, a button cell was assembled using LiMn2O4 as the positive electrode, graphite as the negative electrode, a commercial Al2O3 / PE porous separator, and 1 mol / L LiPF6 (EMC: EC = 1:1, volume ratio) as the electrolyte. After assembly, the button lithium cell was immersed at room temperature for 4 h to obtain a button lithium cell.

[0076] Further, the button lithium cell prepared in Comparative Example 3 was subjected to 0.1C charge-discharge testing, and the voltage range was 2.75-4.2V. The test results are shown in Table 3.

[0077] Table 3 charge-discharge cycle results

[0078]

[0079] Example 4

[0080] (1) 0.6 g MDI trimer, 0.02 g lithium acetate, 1 mL 1 mol / L LiPF6 (DMC: DEC: EC = 1:1:1, volume ratio) were mixed uniformly in an argon-filled glove box to obtain a prepolymer solution in a flowable state.

[0081] (2) In an argon-filled glove box, a button cell was assembled using LiCo 0.3 Ni 0.5 Mn 0.2O2as the positive electrode, metal lithium as the negative electrode, and a commercial Al2O3 / PE porous separator were assembled into a button cell, and the polymer electrolyte prepolymer prepared in step (1) was used as the electrolyte. After assembly, the button cell was immersed at room temperature for 4 h and cured at 50°C for 24 h to obtain a solid-state lithium battery polymerized in situ.

[0082] Further, the solid-state lithium battery prepared in Example 4 was subjected to 0.1C charge-discharge testing, and the voltage range was 2.75-4.2V. The test results are shown in Table 4.

[0083] Comparative Example 4

[0084] (1) In an argon-filled glove box, LiCo 0.3 Ni 0.5 Mn 0.2 O2as the positive electrode, metal lithium as the negative electrode, and a commercial Al2O3 / PE porous separator were assembled into a button cell, and the polymer electrolyte prepolymer prepared in step (1) was used as the electrolyte. After assembly, the button cell was immersed at room temperature for 4 h and cured at 50°C for 24 h to obtain a solid-state lithium battery polymerized in situ.

[0085] Further, the solid-state lithium battery prepared in Example 4 was subjected to 0.1C charge-discharge testing, and the voltage range was 2.75-4.2V. The test results are shown in Table 4.

[0086] Table 4 Charge-discharge cycle results

[0087]

[0088] Example 5

[0089] (1) 0.6 g of PPDI, 0.3 g of IPDI, 0.1 g of MDI, 0.02 g of lithium acetate, and 1 mL of 1 mol / L LiDFOB (EMC: FEC = 3:1, by volume) were uniformly mixed in an argon-filled glove box to obtain a prepolymer liquid in a flowing state.

[0090] (2) In an argon-filled glove box, LiCo 0.15 Ni 0.8 Al 0.05 O2as the positive electrode, metal lithium as the negative electrode, and a commercial Al2O3 / PE porous separator were assembled into a button cell, and the polymer electrolyte prepolymer prepared in step (1) was used as the electrolyte. After assembly, the button cell was immersed at room temperature for 4 h and cured at 50°C for 24 h to obtain a solid-state lithium battery polymerized in situ.

[0091] (3) In an argon-filled glove box, LiCo 0.15 Ni 0.8 Al 0.05O2as the positive electrode, metal lithium and copper foil composite tape as the negative electrode, and commercial Al2O3 / PE porous separator, 1 mol / L LiDFOB (EMC: FEC = 3: 1, volume ratio) as the electrolyte to assemble a 10 Ah soft package battery. The energy density of the assembled soft package battery was 330 Wh / kg. After assembly, the soft package battery was immersed at room temperature for 4 h, and then solidified at 60°C for 48 h to obtain a solid-state lithium battery prepared in situ by polymerization.

[0092] Further, the solid-state lithium battery prepared in Example 5 was subjected to 0.1C charge-discharge test, and the voltage range was 2.75-4.2V. The test results are shown in Table 5. The soft package battery prepared in step (3) was subjected to full charge state needle puncture test, and the needle puncture results are shown in Table 5.

[0093] Comparative Example 5

[0094] (1) In an argon-filled glove box, LiCo 0.15 Ni 0.8 Al 0.05 O2as the positive electrode, metal lithium as the negative electrode, and commercial Al2O3 / PE porous separator, 1 mol / L LiDFOB (EMC: FEC = 3: 1, volume ratio) as the electrolyte to assemble a 10 Ah soft package battery. The energy density of the assembled soft package battery was 330 Wh / kg. After assembly, the soft package battery was immersed at room temperature for 4 h, and then solidified at 60°C for 48 h to obtain a solid-state lithium battery prepared in situ by polymerization.

[0095] (1) In an argon-filled glove box, LiCo 0.15 Ni 0.8 Al 0.05 O2as the positive electrode, metal lithium as the negative electrode, and commercial Al2O3 / PE porous separator, 1 mol / L LiDFOB (EMC: FEC = 3: 1, volume ratio) as the electrolyte to assemble a 10 Ah soft package battery. The energy density of the assembled soft package battery was 330 Wh / kg. After assembly, the soft package battery was immersed at room temperature for 4 h, and then solidified at 60°C for 48 h to obtain a solid-state lithium battery prepared in situ by polymerization.

[0096] Further, the solid-state lithium battery prepared in Example 5 was subjected to 0.1C charge-discharge test, and the voltage range was 2.75-4.2V. The test results are shown in Table 5. The soft package battery prepared in step (3) was subjected to full charge state needle puncture test, and the needle puncture results are shown in Table 5.

[0097] Table 5 Charge-discharge cycle and needle puncture results

[0098]

[0099] Example 6

[0100] (1) In an argon-filled glove box, 0.5 g DMMDI, 0.3 g PTSI, 0.1 g MDI, 0.02 g lithium acetate, 1 mL 1 mol / L LiPF6(DMC:DEC:EC = 1:1:1, volume ratio) were mixed uniformly to obtain a prepolymer solution in a flow state.

[0101] (2) In an argon-filled glove box, LiCo 0.2 Ni 0.6 Mn 0.2 O2as the positive electrode, graphite as the negative electrode, and a commercial Al2O3 / PE porous separator were assembled into a button cell, and the polymer electrolyte prepolymer prepared in step (1) was used as the electrolyte. After assembly, the button lithium battery was immersed at room temperature for 4 h and cured at 60°C for 24 h to obtain a solid-state lithium battery polymerized in situ.

[0102] Further, the solid-state lithium battery prepared in Example 6 was subjected to 0.1C charge-discharge test, and the voltage range was 2.75-4.2V. The test results are shown in Table 6.

[0103] Comparative Example 6

[0104] (1) In an argon-filled glove box, LiCo 0.2 Ni 0.6 Mn 0.2 O2as the positive electrode, graphite as the negative electrode, and a commercial Al2O3 / PE porous separator, 1 mol / L LiPF6(DMC:DEC:EC = 1:1:1, volume ratio) as the electrolyte were assembled into a button cell, and the button lithium battery was immersed at room temperature for 4 h to obtain a button lithium battery.

[0105] Further, the button lithium battery prepared in Comparative Example 6 was subjected to 0.1C charge-discharge test, and the voltage range was 2.75-4.2V. The test results are shown in Table 6.

[0106] Table 6 Charge-discharge cycle results

[0107]

[0108] Example 7

[0109] (1) In an argon-filled glove box, 0.5 g PFPI, 0.3 g IPDI, 0.1 g MDI, 0.02 g lithium acetate, 1 mL 1 mol / L LiPF6(DMC:DEC:EC = 1:1:1) were mixed uniformly to obtain a prepolymer solution in a flow state.

[0110] (2) In an argon-filled glove box, LiCo 0.1 Ni 0.8 Mn 0.1O2as the positive electrode, metal lithium as the negative electrode and commercial Al2O3 / PE porous separator were assembled into a button cell, and the polymer electrolyte prepolymer prepared in step (1) was used as the electrolyte. After assembly, the button cell was immersed at room temperature for 4 h and cured at 60 °C for 24 h to obtain a solid-state lithium battery polymerized in situ.

[0111] (3) In an argon-filled glove box, LiCo 0.1 Ni 0.8 Mn 0.1 O2as the positive electrode, metal lithium as the negative electrode and commercial Al2O3 / PE porous separator were assembled into a button cell, and the polymer electrolyte prepolymer prepared in step (1) was used as the electrolyte. After assembly, the button cell was immersed at room temperature for 4 h and cured at 60 °C for 24 h to obtain a solid-state lithium battery polymerized in situ.

[0112] Further, the solid-state lithium battery prepared in Example 7 was subjected to 0.1C charge-discharge test, and the voltage range was 2.75-4.2V. The test results are shown in Table 7. The soft package battery prepared in step (3) was subjected to full charge state needle puncture test, and the needle puncture results are shown in Table 7.

[0113] Comparative Example 7

[0114] (1) In an argon-filled glove box, LiCo 0.1 Ni 0.8 Mn 0.1 O2as the positive electrode, metal lithium as the negative electrode and commercial Al2O3 / PE porous separator were assembled into a button cell, and the polymer electrolyte prepolymer prepared in step (1) was used as the electrolyte. After assembly, the button cell was immersed at room temperature for 4 h and cured at 60 °C for 24 h to obtain a solid-state lithium battery polymerized in situ.

[0115] (2) In an argon-filled glove box, LiCo 0.1 Ni 0.8 Mn 0.1 O2as the positive electrode, metal lithium as the negative electrode and commercial Al2O3 / PE porous separator were assembled into a button cell, and the polymer electrolyte prepolymer prepared in step (1) was used as the electrolyte. After assembly, the button cell was immersed at room temperature for 4 h and cured at 60 °C for 24 h to obtain a solid-state lithium battery polymerized in situ.

[0116] Further, the solid-state lithium battery prepared in Example 7 was subjected to 0.1C charge-discharge test, and the voltage range was 2.75-4.2V. The test results are shown in Table 7. The soft package battery prepared in step (3) was subjected to full charge state needle puncture test, and the needle puncture results are shown in Table 7.

[0117] Table 7 Charge-discharge cycle and needle puncture results

[0118]

[0119]

[0120] Example 8

[0121] (1) 0.5 g LDI, 0.3 g MDI, 0.02 g lithium acetate, 1 mL 1 mol / L LiPF6(DMC:DEC:EC = 1:1:1) were mixed uniformly in an argon-filled glove box to obtain a prepolymer solution in a flow state.

[0122] (2) In an argon-filled glove box, LiCo 0.1 Ni 0.8 Mn 0.1 O2 as the positive electrode, graphite as the negative electrode, and a commercial Al2O3 / PE porous separator were assembled into a button cell, and the polymer electrolyte prepolymer prepared in step (1) was used as the electrolyte. After assembly, it was immersed at room temperature for 4 h and cured at 60°C for 24 h to obtain a solid-state lithium battery polymerized in situ.

[0123] (3) In an argon-filled glove box, LiCo 0.1 Ni 0.8 Mn 0.1 O2 as the positive electrode, graphite as the negative electrode, and a commercial Al2O3 / PE porous separator were assembled into a 10 Ah soft-pack battery, and the polymer electrolyte prepolymer prepared in step (1) was used as the electrolyte. The energy density of the assembled soft-pack battery was 350 Wh / kg, and after assembly, it was immersed at room temperature for 4 h and cured at 60°C for 24 h to obtain a solid-state lithium battery polymerized in situ.

[0124] Further, the solid-state lithium battery prepared in Example 8 was subjected to 0.1C charge-discharge test, and the voltage range was 2.75-4.2V. The test results are shown in Table 8. The soft-pack battery prepared in step (3) was subjected to full-charge-state needle-puncture test, and the needle-puncture results are shown in Table 8.

[0125] Table 8 Charge-discharge cycle and needle-puncture results of Example 8

[0126]

[0127] Example 9

[0128] (1) 0.5 g TODI, 0.3 g IPDI, 0.02 g lithium acetate, 1 mL 1 mol / L LiPF6(DMC:DEC:EC = 1:1:1) were mixed uniformly in an argon-filled glove box to obtain a prepolymer solution in a flow state.

[0129] (2) In an argon-filled glove box, LiCo 0.1 Ni0.8 Mn 0.1 O2 as the positive electrode, metal lithium as the negative electrode and a commercial Al2O3 / PE porous separator were assembled into a button cell, and the polymer electrolyte prepolymer prepared in step (1) was used as the electrolyte. After assembly, the button cell was immersed at room temperature for 4 h and cured at 60°C for 24 h to obtain a solid-state lithium battery polymerized in situ.

[0130] (3) In an argon-filled glove box, LiCo 0.1 Ni 0.8 Mn 0.1 O2 as the positive electrode, metal lithium and copper foil composite tape as the negative electrode and a commercial Al2O3 / PE porous separator were assembled into a 10 Ah soft package battery, and the polymer electrolyte prepolymer prepared in step (1) was used as the electrolyte. The energy density of the assembled soft package battery was 350 Wh / kg. After assembly, the soft package battery was immersed at room temperature for 4 h and cured at 60°C for 24 h to obtain a solid-state lithium battery polymerized in situ.

[0131] Further, the solid-state lithium battery prepared in Example 9 was subjected to 0.1C charge-discharge test, and the voltage range was 2.75-4.2V. The test results are shown in Table 9. The soft package battery prepared in step (3) was subjected to full charge state needle puncture test, and the needle puncture results are shown in Table 9.

[0132] Table 9 Charge-discharge cycle and needle puncture results of Example 9

[0133]

[0134] Example 10

[0135] (1) 1 g of PAPI and 0.02 g of LiTFSI were uniformly mixed in an argon-filled glove box to obtain a prepolymer liquid in a flowable state.

[0136] (2) In an argon-filled glove box, LiFePO4 as the positive electrode, graphite as the negative electrode and a commercial Al2O3 / PE porous separator were assembled into a button cell, and the polymer electrolyte prepolymer prepared in step (1) was used as the electrolyte. After assembly, the button cell was immersed at room temperature for 4 h and cured at 60°C for 24 h to obtain a solid-state lithium battery polymerized in situ.

[0137] Further, the solid-state lithium battery prepared in Example 10 was subjected to 0.1C charge-discharge test, and the voltage range was 2.75-3.8V. The test results are shown in Table 10.

[0138] Table 10 Charge-discharge cycle results of Example 10

[0139]

[0140] The foregoing description of the disclosed embodiments enables one of ordinary skill in the art to make or use the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a solid electrolyte from in-situ self-polymerization of isocyanate, comprising the following steps: a) Mix isocyanate monomer, lithium salt, initiator and solvent to obtain monomer prepolymer solution; wherein the initiator is selected from at least one of trialkylphosphine, tertiary amine, quaternary ammonium salt, nitrogen group element compound, organometallic compound and basic carboxylate, and wherein the trialkylphosphine is selected from at least one of triethylphosphine, dimethylphenylphosphine, triphenylphosphine and tri-n-butylphosphine; The tertiary amine is selected from at least one of triethylamine, triethyleneethylenediamine, 2,4,6-tris(dimethylaminomethyl)phenol, N,N,N',N'-tetramethylalkylenediamine, N,N-dimethylcyclohexylamine, N,N-dimethylhexadecanamine, N,N-dimethylbenzylamine, N,N-dimethylbutylamine, bis(2-dimethylaminoethyl) ether, (dimethylaminoethyl) ether, triethanolamine, N,N-dimethylethanolamine, methyldiethylene glycolamine, and triethylenediamine. The quaternary ammonium salt is selected from at least one of tetramethylammonium octanoate, N-hydroxyalkyl quaternary ammonium base, and trimethyl-N-2-hydroxypropylhexanoic acid; The organometallic compound is selected from at least one of cesium fluoride, tributyltin oxide, tetrabutyl titanate, tetrabutyl zirconate, dialkyltin oxide, butyllithium, trialkyltin alkoxide, lithium bis(trifluoromethanesulfonyl)imide, and lithium bis(fluorosulfonyl)imide. The alkaline carboxylate is selected from at least one of lithium acetate, potassium acetate, and potassium carboxylate; The nitrogen group compound is selected from at least one of pyridine, tris(dimethylaminopropyl)hexahydrotriazine, N-ethylmorpholine, N-methylmorpholine, N-methylethylenediamine, dimethylformamide, and hexamethyldisilazane; b) The monomer prepolymer liquid obtained in step a) is injected into the battery for wetting, and then polymerized to obtain a solid electrolyte; The solid electrolyte contains an isocyanurate carbon-nitrogen ring structure.

2. The preparation method according to claim 1, characterized in that, The isocyanate monomers mentioned in step a) are selected from toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, biuret triisocyanate, lysine diisocyanate, phenylmethylene diisocyanate, tetramethylxylene diisocyanate, 1,5-naphthalene diisocyanate, 3,3'-dimethyl-4,4'-biphenyl diisocyanate, 1,4-cyclohexyl diisocyanate, trimethyl-1,6-hexamethylene diisocyanate, and tetramethyltoluene diisocyanate. Diisocyanate, methylcyclohexyl diisocyanate, decamethyl diisocyanate, 1,12-dodecane diisocyanate, 2,2,4-trimethylcyclohexyl diisocyanate, triphenylmethane triisocyanate, 4,4',4''-triphenylthiophosphate triisocyanate, cyclohexane dimethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, 4,4'-diphenyl diisocyanate, norbornene diisocyanate, p-phenylene diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 3,3'-dimethoxy Biphenyl-4,4'-diisocyanate, 2-methylpentane diisocyanate, 4,4'-diphenyl ether diisocyanate, 4-methyldiphenylmethane-3,4-diisocyanate, 2,4'-diphenyl sulfide diisocyanate, diethylphenyl diisocyanate, 4,4'-diphenylethane diisocyanate, dimethyldiphenylmethylene diisocyanate, isopropylidene bis(4-isocyanatocyclohexane) and diisocyanate derivatives, triphenylmethane-4,4'-4”-triisocyanate, tri(4-phenylisocyanate) thiophosphate, dimethyltriphenylmethane tetraisocyanate, p-toluenesulfonyl Isocyanates (PTSI), pentafluorophenyl isocyanates (PFPI), C-MDI polyisocyanates, and dimers, trimers, and polymers of the above isocyanates; the diisocyanate derivatives include liquefied MDI, TDI dimers, TDI trimers, TDI-TMP adducts, TDI-HDI mixed polymers, HDI adducts, HDI dimers, HDI trimers, HDI biuret, HDI urethane, IPDI trimers, H6XDI trimers, XDI adducts, H6XDI adducts, IPDI adducts, and HDI prepolymers.

3. The preparation method according to claim 1, characterized in that, The lithium salt mentioned in step a) is selected from one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium dioxalateborate, lithium difluorooxalateborate, lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluoroarsenate, lithium tetrafluoroborate, lithium perchlorate, lithium difluorophosphate, and lithium hexafluorophosphate.

4. The preparation method according to claim 1, characterized in that, The solvent mentioned in step a) is selected from one or more of the following: ethylene carbonate, fluoroethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, butyl carbonate, methyl propyl carbonate, methyl formate, ethyl formate, propyl formate, butyl formate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, δ-valerolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 4-methyl-1,3-dioxolane, 2-methyl-1,3-dioxolane, ethylene glycol dimethyl ether, 1,3-dioxolane, sulfolane, and dimethyl sulfoxide.

5. The preparation method according to claim 1, characterized in that, The steps described in step a) The mass ratio of isocyanate monomer, lithium salt, initiator and solvent is (5~95):(5~30):(0~5):(0~60).

6. The preparation method according to claim 1, characterized in that, The soaking time described in step b) is 2h to 24h.

7. The preparation method according to claim 1, characterized in that, The polymerization process described in step b) is carried out under heating conditions; the polymerization temperature is 20℃~130℃ and the time is 5h~120h.

8. A solid-state battery, comprising a positive electrode, a negative electrode, a separator, and an in-situ solidified electrolyte, characterized in that... The in-situ solid electrolyte is a solid electrolyte prepared by in-situ self-polymerization of isocyanate monomers according to any one of claims 1-7.

9. The solid-state battery according to claim 8, characterized in that... The positive electrode active material is one or more of lithium cobalt oxide, lithium nickel cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide, ternary lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese aluminum oxide, lithium manganese iron phosphate, lithium iron phosphate, sulfur, and lithium sulfide; the negative electrode material is one or more of lithium metal, lithium metal alloy, graphite, hard carbon, molybdenum disulfide, lithium titanate, graphene, silicon, silicon carbon, silicon oxide, and silicon oxide carbon negative electrode; the separator is one or more of commercially available PP, PE, PI, cellulose membrane, PET porous membrane, and ceramic coated membrane.

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