In-situ polymerization solid-state battery with multilayer electrolyte and preparation method thereof

Abstract

The present invention provides an in-situ polymerized solid-state battery with a multilayer structure electrolyte, wherein the multilayer structure electrolyte comprises an oxidation-resistant polymer layer formed in-situ on the positive electrode side and a reduction-resistant polymer layer formed in-situ on the negative electrode side. The present invention is to pre-place a monomer or initiator that can form an oxidation-resistant polymer through a chemical reaction on the positive electrode plate during the mixing process, and to pre-place a monomer or initiator that can form a reduction-resistant polymer through a chemical reaction on the negative electrode plate during the mixing process, and then inject the monomer that reacts therewith into the battery by liquid injection to initiate a polymerization reaction, so as to achieve in-situ polymerization inside the battery to form a multilayer structure electrolyte that is oxidation-resistant at the positive electrode and reduction-resistant at the negative electrode, thereby improving the safety and cycle stability of the in-situ polymerized battery, reducing the interface impedance between the electrolyte and the electrode in the battery, and the method is simple and easy to expand production. The present invention also provides a method for preparing an in-situ polymerized solid-state battery with a multilayer structure electrolyte.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium ion batteries, and in particular relates to an in-situ polymerized solid-state battery with a multilayer electrolyte structure and a preparation method thereof. Background Art

[0002] Currently, large-scale commercial lithium secondary batteries contain a large amount of flammable and leaky organic carbonate small molecule solvents, which pose a major safety hazard. Using non-volatile and non-combustible solid electrolytes to replace traditional electrolytes is considered an effective way to solve the safety problem of lithium-ion batteries. Among them, polymer electrolytes have become a hot topic of research in recent years due to their small interfacial impedance and high safety. However, due to the complex process and the stability of the electrical properties of the polymer itself, they have not entered mass production quickly.

[0003] In order to improve the preparation process of polymer lithium batteries and improve production efficiency, researchers have proposed an in-situ curing technology, which injects liquefied monomers into the battery core by liquid injection, and then initiates monomer polymerization under certain conditions to form an in-situ solid-state battery after the infiltration is completed. For example, CN105914405A proposes a method of injecting liquid epoxy compounds and lithium salts into the battery, and initiating in-situ ring-opening curing under heating conditions to form an integrated all-solid-state polymer battery; CN108493486A uses acrylates and initiators dissolved in electrolytes, injected into the battery, and initiating unsaturated double bond polymerization under heating conditions to form an integrated gel polymer battery; CN111533851A uses a mixture of small molecule carbonates containing double bonds, ethylene glycol acrylates, and initiators to be injected into the interface of the solid-state battery, and thermally initiates polymerization to form an electrode-electrolyte integrated all-solid-state battery; CN111540956A dissolves isocyanates and polypropylene glycol in electrolytes and injects them into the battery to form an integrated battery, reducing the electrode-electrolyte interface impedance.

[0004] Lithium-ion batteries have a wide voltage range. Usually, a polymer material cannot take into account both high-voltage and low-voltage stability at the same time. To solve this problem, researchers have developed a multi-layer composite electrolyte membrane. The positive and negative electrodes are respectively composed of oxidation-resistant and reduction-resistant polymer components, which significantly improve the electrochemical stability window of the electrolyte. For example, CN109565078A provides a multi-layer electrolyte. Polyester and polyether electrolyte films are prepared by solvent volatilization. Ester with strong oxidation resistance and ether with strong ion conductivity and smaller interface impedance are prepared into a composite membrane. The cycle stability of the assembled solid-state battery is significantly improved; CN1 10048158A uses a casting method to in-situ polymerize on both sides of a porous membrane to form a double-layer electrolyte membrane with one side being ester and the other side being ether. This membrane simultaneously meets the stability requirements of the high-voltage positive electrode and the low-voltage negative electrode; CN110581314A coats an inorganic solid electrolyte on the side of the support membrane in contact with the positive electrode, and coats a polymer electrolyte on the side of the support membrane in contact with the negative electrode, which reduces electrolyte oxidation and improves the safety and cycle stability of the battery; however, the multi-layer composite membrane process reported so far is complex, and most of them are coated on the outside of the battery cell and then composited with the pole piece. The contact between the electrolyte and the electrode interface is poor, and the impedance is large, which is not conducive to the battery capacity. Summary of the invention

[0005] The object of the present invention is to provide an in-situ polymerization solid-state battery with a multilayer structure electrolyte and a preparation method thereof. The present invention adopts an in-situ polymerization method to form a multilayer structure electrolyte inside the battery at one time, which has both the positive electrode's resistance to high voltage and the negative electrode's resistance to reduction, greatly simplifying the preparation process of the multilayer structure electrolyte battery. The preparation method of the present invention improves the interface contact between the electrode and the electrolyte, thereby improving the safety and cycle stability of the battery cell. At the same time, it is compatible with existing lithium-ion battery production processes and equipment, and can be quickly mass-produced.

[0006] The present invention provides an in-situ polymerized solid-state battery having a multilayer structure electrolyte, wherein the multilayer structure electrolyte comprises an oxidation-resistant polymer layer formed in-situ on the positive electrode side and a reduction-resistant polymer layer formed in-situ on the negative electrode side;

[0007] The in-situ polymerization solid-state battery with a multilayer structure electrolyte is prepared according to the following steps:

[0008] A) mixing the first pre-set monomer with the positive electrode slurry, and coating to obtain a composite positive electrode; mixing the second pre-set monomer with the negative electrode slurry, and coating to obtain a composite negative electrode;

[0009] B) assembling a battery cell using the composite positive electrode and the composite negative electrode;

[0010] C) injecting electrolyte into the battery core to initiate monomer polymerization to form a multilayer structure electrolyte;

[0011] The electrolyte contains a first reactive monomer and a second reactive monomer;

[0012] The first pre-set monomer reacts chemically with the first reactive monomer in the electrolyte to generate an oxidation-resistant polymer; the second pre-set monomer reacts chemically with the second reactive monomer in the electrolyte to generate a reduction-resistant polymer.

[0013] Preferably, the mass fraction of the first pre-set monomer in the positive electrode slurry is 0.01-35%; the mass fraction of the second pre-set monomer in the negative electrode slurry is 0.01-35%.

[0014] Preferably, the mass fraction of the first reaction monomer in the electrolyte is 0.01-50%; the mass fraction of the second reaction monomer in the electrolyte is 0.01-50%.

[0015] Preferably, the first pre-set monomer is a first polymer monomer or a first initiator;

[0016] The first polymer monomer includes one or more of ester monomers, carbonate monomers, sulfone monomers, isocyanates, amide monomers, nitrile monomers and fluorinated monomers;

[0017] The first initiator includes one or more of an azo initiator, a peroxide initiator, an anionic and cationic initiator, an organic metal compound initiator, an amine catalyst initiator and an organic phosphorus initiator.

[0018] Preferably, the first polymer monomer comprises vinyl acetate, dimethyl allyl dicarboxylate, diethyl allyl malonate, methallyl carbonate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, methyl methacrylate, butyl methacrylate, vinylene carbonate, vinyl ethylene carbonate, methyl vinyl sulfone, ethyl vinyl sulfone, vinyl acetate, 1,4-butanediol ester diol, polycarbonate diol, polyethylene adipate diol, ethoxylated trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate. One or more of ester, dipentaerythritol hexaacrylate, acrylamide, N,N-methylenebisacrylamide, N-methylmaleamide, N-ethylmaleamide, caprolactam, butyrolactam, maleic anhydride, acrylonitrile, 2-cyanoethyl acrylate, 2-cyano-2-butyl acrylate, 2-cyano-3,3-diphenylacrylate isooctyl ester, 1-cyclohexeneacetonitrile, hexafluorobutyl methacrylate, trifluoroethyl methacrylate, dihydroxyethyl terephthalate, toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate and hexamethylene diisocyanate.

[0019] Preferably, the first initiator includes one or more of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, benzoyl peroxide, tert-butyl benzoyl peroxide, methyl ethyl ketone peroxide, stannous octoate, lithium acetate, triethyl phosphine, triphenyl phosphine, tri-n-butyl phosphine, tributyltin oxide, tetrabutyl titanate, tetrabutyl zirconate, trialkyltin alkoxide, dialkyltin oxide, N-methylethylenediamine, dimethylformamide, triethyleneethylenediamine, methyldiethylene glycolamine, triethylenediamine, aluminum trifluoromethylsulfonate, magnesium trifluoromethylsulfonate, lithium bis(fluorosulfonyl)imide and tin trifluoromethylsulfonate.

[0020] Preferably, the second pre-set monomer is a second polymer monomer or a second initiator;

[0021] The second polymer monomer includes one or more of an ether compound, an ether segment-containing oligomer and a siloxane;

[0022] The second initiator includes one or more of an azo initiator, a peroxide initiator, an anionic and cationic initiator, an organic metal compound initiator, an amine catalyst initiator and an organic phosphorus initiator.

[0023] Preferably, the second polymer monomer includes one or more of polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, ethoxyethoxyethyl acrylate, polyethylene glycol, 1,3-dioxolane, dioxane, hydroxy polyether silicone oil, polytetramethylene ether glycol, vinyl methoxysilane, 2-(trimethylsiloxy)ethyl methacrylate, trivinylcyclotrisiloxane, tri(2-methoxyethoxy)vinyl silane, octahydroxypropyldimethylsilyl-POSS, polyetheramine, and trihydroxymethylpropane triglycidyl ether.

[0024] Preferably, the second initiator includes one or more of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, benzoyl peroxide, tert-butyl benzoyl peroxide, methyl ethyl ketone peroxide, stannous octoate, lithium acetate, triethyl phosphine, triphenyl phosphine, tri-n-butyl phosphine, tributyltin oxide, tetrabutyl titanate, tetrabutyl zirconate, trialkyltin alkoxide, dialkyltin oxide, N-methylethylenediamine, dimethylformamide, triethyleneethylenediamine, methyldiethylene glycolamine, triethylenediamine, aluminum trifluoromethylsulfonate, magnesium trifluoromethylsulfonate, lithium bis(fluorosulfonyl)imide and tin trifluoromethylsulfonate.

[0025] The present invention provides a method for preparing an in-situ polymerized solid-state battery having a multilayer structure electrolyte as described above, comprising the following steps:

[0026] A) mixing the first pre-set monomer with the positive electrode slurry, and coating to obtain a composite positive electrode; mixing the second pre-set monomer with the negative electrode slurry, and coating to obtain a composite negative electrode;

[0027] B) assembling a battery cell using the composite positive electrode and the composite negative electrode;

[0028] C) injecting electrolyte into the battery core to initiate monomer polymerization to form a multilayer structure electrolyte;

[0029] The electrolyte contains a first reactive monomer and a second reactive monomer;

[0030] The first pre-set monomer reacts chemically with the first reactive monomer in the electrolyte to generate an oxidation-resistant polymer; the second pre-set monomer reacts chemically with the second reactive monomer in the electrolyte to generate a reduction-resistant polymer.

[0031] Preferably, the polymerization is initiated by heating in step C); the heating temperature is 25 to 90° C.; and the heating time is 1 to 120 hours.

[0032] The present invention provides an in-situ polymerized solid-state battery with a multilayer structure electrolyte, wherein the multilayer structure electrolyte comprises an oxidation-resistant polymer layer formed in-situ on the positive electrode side and a reduction-resistant polymer layer formed in-situ on the negative electrode side. The specific preparation method comprises the following steps: A) mixing a first pre-set monomer with the positive electrode slurry, and obtaining a composite positive electrode after coating; mixing a second pre-set monomer with the negative electrode slurry, and obtaining a composite negative electrode after coating; B) assembling a battery cell using the composite positive electrode and the composite negative electrode; C) injecting an electrolyte into the battery cell to initiate monomer polymerization to form a multilayer structure electrolyte; the electrolyte contains a first reaction monomer and a second reaction monomer; the first pre-set monomer reacts chemically with the first reaction monomer in the electrolyte to generate an oxidation-resistant polymer; the second pre-set monomer reacts chemically with the second reaction monomer in the electrolyte to generate a reduction-resistant polymer. The method of forming a multi-layer structure electrolyte in situ inside the battery of the present invention is to pre-place a monomer or initiator that can form an oxidation-resistant polymer through a chemical reaction on the positive electrode plate during the mixing process, and to pre-place a monomer or initiator that can form a reduction-resistant polymer through a chemical reaction on the negative electrode plate during the mixing process, and then inject the monomer that reacts with it into the battery by liquid injection to initiate a polymerization reaction, so as to achieve in-situ polymerization inside the battery to form a multi-layer structure electrolyte with oxidation resistance at the positive electrode and reduction resistance at the negative electrode, thereby improving the safety and cycle stability of the in-situ polymerization battery. The in-situ polymerization method is adopted to reduce the interface impedance of the electrolyte and the electrode in the battery, and the method is simple and easy to expand production. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0034] Figure 1 It is a comparison chart of the cycle performance of the batteries in Example 1, Comparative Example 6 and Comparative Example 7 of the present invention;

[0035] Figure 2 This is a comparison chart of the cycle performance of the batteries in Example 3, Comparative Example 8 and Comparative Example 9 of the present invention;

[0036] Figure 3 It is a comparison chart of the cycle performance of the batteries in Example 4, Comparative Example 10 and Comparative Example 11 of the present invention. DETAILED DESCRIPTION

[0037] The present invention provides an in-situ polymerized solid-state battery having a multilayer structure electrolyte, wherein the multilayer structure electrolyte comprises an oxidation-resistant polymer layer formed in-situ on the positive electrode side and a reduction-resistant polymer layer formed in-situ on the negative electrode side;

[0038] The in-situ polymerization solid-state battery with a multilayer structure electrolyte is prepared according to the following steps:

[0039] A) mixing the first pre-set monomer with the positive electrode slurry, and coating to obtain a composite positive electrode; mixing the second pre-set monomer with the negative electrode slurry, and coating to obtain a composite negative electrode;

[0040] B) assembling a battery cell using the composite positive electrode and the composite negative electrode;

[0041] C) injecting electrolyte into the battery core to initiate monomer polymerization to form a multilayer structure electrolyte;

[0042] The electrolyte contains a first reactive monomer and a second reactive monomer;

[0043] The first pre-set monomer reacts chemically with the first reactive monomer in the electrolyte to generate an oxidation-resistant polymer; the second pre-set monomer reacts chemically with the second reactive monomer in the electrolyte to generate a reduction-resistant polymer.

[0044] The present invention mixes the first pre-set monomer with the positive electrode slurry to obtain a composite positive electrode slurry, applies the composite positive electrode slurry to a current collector, and obtains a composite positive electrode after drying.

[0045] In the present invention, the first pre-set monomer reacts chemically with the first reactive monomer in the electrolyte to generate an oxidation-resistant polymer; the first pre-set monomer may be a first polymer monomer or a first initiator.

[0046] In the present invention, the first polymer monomer preferably includes one or more of ester monomers, carbonate monomers, sulfone monomers, isocyanates, amide monomers, nitrile monomers and fluorinated monomers; more preferably, vinyl acetate, dimethyl allyl dicarboxylate, diethyl allyl malonate, methallyl carbonate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, methyl methacrylate, butyl methacrylate, vinyl carbonate, vinyl ethylene carbonate, methyl vinyl sulfone, ethyl vinyl sulfone, vinyl acetate, 1,4-butanediol ester diol, polycarbonate diol, polyethylene adipate diol, ethoxylated trimethylolpropane triacrylate, quaternary One or more of pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, acrylamide, N,N-methylenebisacrylamide, N-methylmaleamide, N-ethylmaleamide, caprolactam, butyrolactam, maleic anhydride, acrylonitrile, 2-cyanoethyl acrylate, 2-cyano-2-butyl acrylate, 2-cyano-3,3-diphenylacrylate isooctyl ester, 1-cyclohexeneacetonitrile, hexafluorobutyl methacrylate, trifluoroethyl methacrylate, dihydroxyethyl terephthalate, toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate and hexamethylene diisocyanate.

[0047] In the present invention, some oligomers, such as polycarbonate diol and polyethylene adipate diol, may also be used in the first polymer monomer. The oligomer may undergo polymerization to form an oxidation-resistant polymer. For example, in some specific embodiments of the present invention, the oligomer as the first polymer monomer may include polycarbonate diol (PCDL) having a molecular weight of 2000.

[0048] In the present invention, the first initiator is preferably one or more of an azo initiator, a peroxide initiator, an anionic and cationic initiator, an organometallic compound initiator, an amine catalyst initiator and an organophosphorus initiator; more preferably one or more of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, benzoyl peroxide, tert-butyl benzoyl peroxide, methyl ethyl ketone peroxide, stannous octoate, lithium acetate, triethyl phosphine, triphenyl phosphine, tri-n-butyl phosphine, tributyltin oxide, tetrabutyl titanate, tetrabutyl zirconate, trialkyltin alkoxide, dialkyltin oxide, N-methylethylenediamine, dimethylformamide, triethyleneethylenediamine, methyldiethylene glycolamine, triethylenediamine, aluminum trifluoromethylsulfonate, magnesium trifluoromethylsulfonate, lithium bis(fluorosulfonyl)imide and tin trifluoromethylsulfonate.

[0049] In the present invention, the mass fraction of the first pre-set monomer in the positive electrode slurry is 0.01-35%, preferably 0.1-35%, and more preferably 1-30%, such as 0.01%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 4%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, preferably a range value with any of the above values ​​as the upper or lower limit.

[0050] In the present invention, the positive electrode slurry includes a positive electrode material, a conductive agent, a binder, and a solvent; the mass ratio of the positive electrode material, the conductive agent, and the binder is (5-10):(0.5-2):(0.5-2), and more preferably 9:0.5:0.5; the solid content of the slurry is 45-60%, and more preferably 50-55%; the positive electrode material is preferably 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 conductive agent is preferably conductive carbon black, Ketjen black, carbon nanotubes, etc.; the binder is preferably polyvinylidene fluoride; the solvent is preferably N-methylpyrrolidone.

[0051] In the present invention, the positive electrode current collector may be a current collector commonly used in the art, such as an aluminum foil current collector.

[0052] In the present invention, the drying temperature is preferably 80-110°C, more preferably 85-105°C, such as 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, preferably a range value with any of the above values ​​as the upper or lower limit; the drying time is preferably 0.1-5 hours, more preferably 0.5-4.5 hours, such as 0.1 hour, 0.5 hour, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, preferably a range value with any of the above values ​​as the upper or lower limit.

[0053] The present invention mixes the second pre-set monomer with the negative electrode slurry to obtain a composite negative electrode slurry, and applies the composite negative electrode slurry to a current collector, and then dries the composite negative electrode to obtain a composite negative electrode.

[0054] In the present invention, the second pre-set monomer reacts chemically with the second reactive monomer in the electrolyte to generate a reduction-resistant polymer; the second pre-set monomer may be a second polymer monomer or a second initiator.

[0055] In the present invention, the second polymer monomer preferably includes one or more of ether compounds, ether-containing segment oligomers and siloxanes, and more preferably one or more of polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, ethoxyethoxyethyl acrylate, polyethylene glycol, 1,3-dioxolane (DOL), dioxane, hydroxy polyether silicone oil, polytetramethylene ether glycol, vinyl methoxysilane, 2-(trimethylsiloxy)ethyl methacrylate, trivinylcyclotrisiloxane, tri(2-methoxyethoxy)vinylsilane, octahydroxypropyldimethylsilyl-POSS, polyetheramine and trihydroxymethylpropane triglycidyl ether.

[0056] In the present invention, some oligomers may also be used in the first polymer monomer, such as polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol, polytetramethylene glycol, polyetheramine. The oligomer may be polymerized to form a reduction-resistant polymer. For example, in some specific embodiments of the present invention, the oligomer as the second polymer monomer may include polyethylene glycol (PEG) having a molecular weight of 10,000.

[0057] The second initiator is preferably one or more of an azo initiator, a peroxide initiator, an anionic and cationic initiator, an organic metal compound initiator, an amine catalyst initiator and an organic phosphorus initiator, and more preferably one or more of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, benzoyl peroxide, tert-butyl benzoyl peroxide, methyl ethyl ketone peroxide, stannous octoate, lithium acetate, triethyl phosphine, triphenyl phosphine, tri-n-butyl phosphine, tributyltin oxide, tetrabutyl titanate, tetrabutyl zirconate, trialkyltin alkoxide, dialkyltin oxide, N-methylethylenediamine, dimethylformamide, triethyleneethylenediamine, methyldiethylene glycolamine, triethylenediamine, aluminum trifluoromethylsulfonate, magnesium trifluoromethylsulfonate, lithium bis(fluorosulfonyl)imide and tin trifluoromethylsulfonate.

[0058] In the present invention, the mass fraction of the second pre-set monomer in the negative electrode slurry is 0.01-35%, preferably 0.1-35%, more preferably 1-30%, such as 0.01%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 4%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, preferably with any of the above values ​​as the upper or lower limit of the range value.

[0059] In the present invention, the negative electrode slurry includes a negative electrode material, a conductive agent, a binder, and a solvent; the mass ratio of the negative electrode material, the conductive agent, and the binder is (5-10):(0.5-2):1, and more preferably 8:1:1; the solid content of the slurry is 45-60%, and more preferably 50-60%; the negative electrode material is preferably one or more of metallic lithium, metallic lithium alloy, graphite, hard carbon, molybdenum disulfide, lithium titanate, graphene, silicon, silicon carbon, silicon oxygen, and silicon oxygen carbon negative electrode; the conductive agent is preferably conductive carbon black, Ketjen black, and carbon nanotubes; the binder is preferably styrene-butadiene rubber, sodium carboxymethyl cellulose, and lithium polymethacrylate; the solvent is preferably water or N-methylpyrrolidone.

[0060] In the present invention, the negative electrode current collector may be a current collector commonly used in the art, such as a copper foil current collector.

[0061] In the present invention, the drying temperature is preferably 85 to 100° C., more preferably 90 to 95° C.; the drying time is preferably 0.5 to 2 hours, more preferably 1 to 1.5 hours.

[0062] After obtaining the composite positive electrode and the composite negative electrode, the present invention assembles the composite positive electrode and the composite negative electrode into a battery cell, and then injects an electrolyte containing the first reaction monomer and the second reaction monomer into the battery cell, initiates polymerization under certain conditions, and forms a multilayer structure electrolyte.

[0063] In the present invention, the first pre-set monomer can react chemically with the first reactive monomer in the electrolyte to generate an oxidation-resistant polymer. For example, the first pre-set monomer is a first polymer monomer, the first reactive monomer is a monomer that can copolymerize with the first pre-set monomer, or a first initiator that initiates polymerization of the first pre-set monomer, or a mixture of the two; the first pre-set monomer is a first initiator, and the first reactive monomer is a monomer that can be initiated to polymerize to generate an oxidation-resistant polymer.

[0064] Similarly, the second pre-set monomer can react chemically with the second reactive monomer in the electrolyte to generate a reduction-resistant polymer. For example, the second pre-set monomer is a second polymer monomer, the second reactive monomer is a monomer that can copolymerize with the second pre-set monomer, or a second initiator that initiates polymerization of the second pre-set monomer, or a mixture of the two; the second pre-set monomer is a second initiator, and the second reactive monomer is a monomer that can be initiated to polymerize to generate a reduction-resistant polymer.

[0065] In the present invention, the amount of the first reaction monomer and the second reaction monomer is related to the amount of the first pre-set monomer and the second pre-set monomer. Those skilled in the art can select and adjust the amount of the first reaction monomer and the second reaction monomer according to the amount of the first pre-set monomer and the second pre-set monomer to make the reaction complete. Preferably, in the present invention, the mass fraction of the first reaction monomer in the electrolyte is 0.01-50%, preferably 0.1-50%, more preferably 1-40%, such as 0.01%, 0.1%, 0.5%, 1%, 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, preferably a range value with any of the above values ​​as the upper or lower limit; the mass fraction of the second reaction monomer in the electrolyte is 0.01-50%, preferably 0.1-50%, more preferably 1-40%, such as 0.01%, 0.1%, 0.5%, 1%, 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, preferably a range value with any of the above values ​​as the upper or lower limit.

[0066] In the present invention, the electrolyte also includes a solvent, and the solvent preferably includes one or more of ethylene carbonate (EC), fluoroethylene carbonate (FEC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), 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, ethylene glycol dimethyl ether (DME), tetraethylene glycol dimethyl ether, δ-valerolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 4-methyl-1,3-dioxolane, 2-methyl-1,3-dioxolane, 1,3 dioxolane (DOL), sulfolane and dimethyl sulfoxide.

[0067] The electrolyte also includes a lithium salt, and the lithium salt preferably includes one or more of lithium bis(trifluoromethylsulfonyl)imide, lithium bis(oxalatoborate), lithium bis(fluorosulfonyl)imide, lithium hexafluoroarsenate, lithium tetrafluoroborate, lithium perchlorate and lithium hexafluorophosphate.

[0068] The present invention also provides a method for preparing an in-situ polymerized solid-state battery having a multilayer structure electrolyte, comprising the following steps:

[0069] A) mixing the first pre-set monomer with the positive electrode slurry, and coating to obtain a composite positive electrode; mixing the second pre-set monomer with the negative electrode slurry, and coating to obtain a composite negative electrode;

[0070] B) assembling a battery cell using the composite positive electrode and the composite negative electrode;

[0071] C) injecting electrolyte into the battery core to initiate monomer polymerization to form a multilayer structure electrolyte;

[0072] The electrolyte contains a first reactive monomer and a second reactive monomer;

[0073] The first pre-set monomer reacts chemically with the first reactive monomer in the electrolyte to generate an oxidation-resistant polymer; the second pre-set monomer reacts chemically with the second reactive monomer in the electrolyte to generate a reduction-resistant polymer.

[0074] In the present invention, the types and amounts of the raw materials are consistent with the types and amounts of the raw materials described above, and the present invention will not be repeated here.

[0075] The present invention preferably heats the electrolyte to initiate polymerization. In the present invention, the heating temperature is 25 to 90°C, preferably 25 to 80°C, more preferably 30 to 75°C, such as 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, preferably with any of the above values ​​as the upper or lower limit of the range value; the heating time is 1 to 120 hours, preferably 4 to 120 hours, more preferably The range is selected to be 10 to 100 hours, such as 1 hour, 2 hours, 3 hours, 4 hours, 10 hours, 15 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours, 45 hours, 50 hours, 55 hours, 60 hours, 65 hours, 70 hours, 75 hours, 80 hours, 85 hours, 90 hours, 95 hours, 100 hours, 105 hours, 110 hours, 115 hours, or 120 hours, preferably with any of the above values ​​as the upper or lower limit.

[0076] The solid-state battery with a multilayer electrolyte prepared by the preparation method of the present invention has an oxidation-resistant polymer layer on the positive electrode side and a reduction-resistant polymer layer on the negative electrode side. It not only takes into account the good oxidation resistance of the positive electrode side and the good reduction resistance of the negative electrode side, but also improves the interface contact between the electrode and the electrolyte, thereby improving the safety and cycle stability of the battery cell.

[0077] The present invention provides an in-situ polymerized solid-state battery with a multilayer structure electrolyte, wherein the multilayer structure electrolyte comprises an oxidation-resistant polymer layer formed in-situ on the positive electrode side and a reduction-resistant polymer layer formed in-situ on the negative electrode side. The specific preparation method comprises the following steps: A) mixing a first pre-set monomer with the positive electrode slurry, and obtaining a composite positive electrode after coating; mixing a second pre-set monomer with the negative electrode slurry, and obtaining a composite negative electrode after coating; B) assembling a battery cell using the composite positive electrode and the composite negative electrode; C) injecting an electrolyte into the battery cell to initiate monomer polymerization to form a multilayer structure electrolyte; the electrolyte contains a first reaction monomer and a second reaction monomer; the first pre-set monomer reacts chemically with the first reaction monomer in the electrolyte to generate an oxidation-resistant polymer; the second pre-set monomer reacts chemically with the second reaction monomer in the electrolyte to generate a reduction-resistant polymer. The method of forming a multi-layer structure electrolyte in situ inside the battery of the present invention is to pre-place a monomer or initiator that can form an oxidation-resistant polymer after a chemical reaction on the positive electrode plate during the mixing process, and pre-place a monomer or initiator that can form a reduction-resistant polymer after a chemical reaction on the negative electrode plate during the mixing process, and then inject the monomer or initiator that can react with the positive electrode into the battery by liquid injection, and initiate polymerization under certain conditions, so as to achieve a solid-state battery with a multi-layer structure electrolyte that is oxidation-resistant at the positive electrode and reduction-resistant at the negative electrode by in-situ polymerization inside the battery, thereby improving the safety and cycle stability of the in-situ polymerization battery. The in-situ polymerization method is adopted to reduce the interface impedance of the electrolyte and the electrode in the battery, and the method is simple and easy to expand production.

[0078] In order to further illustrate the present invention, an in-situ polymerization solid-state battery with a multilayer structure and a preparation method thereof provided by the present invention are described in detail below in combination with embodiments, but it should not be construed as limiting the scope of protection of the present invention.

[0079] Example 1

[0080] (1) 0.5 g of polycarbonate diol (PCDL) with a molecular weight of 2000 was mixed into 10 g of positive electrode slurry and stirred evenly. The positive electrode slurry contained 50% wt of solvent N-methylpyrrolidone and the solid component ratio was LiCo 0.1 Ni 0.8 Mn 0.1 O2: PVDF: conductive carbon black = 9:0.5:0.5; after coating and drying, the blended positive electrode is obtained.

[0081] (2) 0.3 g of polyethylene glycol (PEG10000) with a molecular weight of 10,000 was mixed into 10 g of negative electrode slurry and stirred evenly. The negative electrode slurry contained 50% wt of solvent N-methylpyrrolidone, and the solid component ratio was graphite: PVDF: conductive carbon black = 8:1:1; after coating and drying, a blended negative electrode was obtained.

[0082] (3) 0.2 g of toluene diisocyanate (TDI) was dissolved in 5 g of DME-1M LiTFSI electrolyte to obtain a blended electrolyte.

[0083] Assemble a battery with the blended electrodes of step (1) and (2) and the blended electrolyte of step (3), and place the assembled battery in an oven at 80°C for curing for 24 hours to form a multilayer polymer electrolyte with PCDL+TDI on the positive electrode side and PEG10000+TDI on the negative electrode side.

[0084] Example 2

[0085] (1) 0.5 g of polycarbonate diol (PCDL) with a molecular weight of 2000 was mixed into 10 g of positive electrode slurry and stirred evenly. The positive electrode slurry contained 50% wt of solvent N-methylpyrrolidone and the solid component ratio was LiCo 0.1 Ni 0.8 Mn 0.1 O2: PVDF: conductive carbon black = 9:0.5:0.5; after coating and drying, the blended positive electrode is obtained.

[0086] (2) 1 g of lithium bis(fluorosulfonyl)imide (LiFSI) was mixed into 10 g of negative electrode slurry and stirred evenly. The negative electrode slurry contained 50% wt of solvent N-methylpyrrolidone, and the solid component ratio was graphite: PVDF: conductive carbon black = 8:1:1. After coating and drying, a blended negative electrode was obtained.

[0087] (3) 0.2 g of toluene diisocyanate (TDI) was dissolved in 5 g of DME / DOL = 1 / 1 1M LiTFSI electrolyte to obtain a blended electrolyte.

[0088] Assemble a battery with the blended electrodes of step (1) and (2) and the blended electrolyte of step (3), and place the assembled battery in an oven at 80° C. for curing for 24 hours to form a multilayer polymer electrolyte with PCDL+TDI on the positive electrode side and DOL polymer on the negative electrode side.

[0089] Example 3

[0090] (1) 0.5 g of polycarbonate diol (PCDL) with a molecular weight of 2000 was mixed into 10 g of positive electrode slurry and stirred evenly. The positive electrode slurry contained 50% wt of solvent N-methylpyrrolidone and the solid component ratio was LiCo 0.1 Ni 0.8 Mn 0.1 O2: PVDF: conductive carbon black = 9:0.5:0.5; after coating and drying, the blended positive electrode is obtained.

[0091] (2) 1 g of lithium bis(fluorosulfonyl)imide (LiFSI) was mixed into 10 g of negative electrode slurry and stirred evenly. The negative electrode slurry contained 50% wt of solvent N-methylpyrrolidone, and the solid component ratio was graphite: PVDF: conductive carbon black = 8:1:1. After coating and drying, a blended negative electrode was obtained.

[0092] (3) 0.2 g of toluene diisocyanate (TDI) and 0.4 g of trimethylolpropane triglycidyl ether (TEGDE) were dissolved in 5 g of DME-1M LiTFSI electrolyte to obtain a blended electrolyte.

[0093] Assemble a battery with the blended electrodes of step (1) and (2) and the blended electrolyte of step (3), and place the assembled battery in an oven at 80° C. for curing for 24 hours to form a multilayer polymer electrolyte with PCDL+TDI on the positive electrode side and TEGDE polymer on the negative electrode side.

[0094] Example 4

[0095] (1) 0.2 g of maleic anhydride (MA) was mixed into 10 g of positive electrode slurry and stirred evenly. The positive electrode slurry contained 50% wt of solvent N-methylpyrrolidone and the solid component ratio was LiCo 0.1 Ni 0.8 Mn 0.1 O2: PVDF: conductive carbon black = 9:0.5:0.5; after coating and drying, the blended positive electrode is obtained.

[0096] (2) 0.3 g of polyethylene glycol (PEG10000) with a molecular weight of 10,000 was mixed into 10 g of negative electrode slurry and stirred evenly. The negative electrode slurry contained 50% wt of solvent N-methylpyrrolidone, and the solid component ratio was graphite: PVDF: conductive carbon black = 8:1:1; after coating and drying, a blended negative electrode was obtained.

[0097] (3) 0.3 g of toluene diisocyanate (TDI), 0.2 g of methyl methacrylate (MMA), and 0.004 g of azobisisobutyronitrile (AIBN) were dissolved in 5 g of DME-1M LiTFSI electrolyte to obtain a blended electrolyte.

[0098] The battery was assembled with the blended electrodes of step (1) and step (2) and the blended electrolyte of step (3), and the assembled battery was placed in an oven at 80°C for curing for 24 hours to form a multilayer polymer electrolyte with MA+MMA on the positive electrode side and TDI+PEG10000 polymer on the negative electrode side. The obtained battery was charged and discharged with a current of 0.1C for 2 cycles, and then charged and discharged with a current of 0.3C for 100 cycles.

[0099] Example 5

[0100] (1) 0.5 g of ethoxylated trimethylolpropane triacrylate (ETPTA) was mixed into 10 g of positive electrode slurry and stirred evenly. The positive electrode slurry contained 50% wt of solvent N-methylpyrrolidone and the solid component ratio was LiCo 0.1 Ni 0.8 Mn 0.1 O2: PVDF: conductive carbon black = 9:0.5:0.5; after coating and drying, the blended positive electrode is obtained.

[0101] (2) 0.2 g of lithium bis(fluorosulfonyl)imide (LiFSI) was mixed into 10 g of negative electrode slurry and stirred evenly. The negative electrode slurry contained 50% wt of solvent N-methylpyrrolidone, and the solid component ratio was graphite: PVDF: conductive carbon black = 8:1:1. After coating and drying, a blended negative electrode was obtained.

[0102] (3) 0.5 g of trimethylolpropane triglycidyl ether (TEGDE), 0.4 g of polyethylene glycol dimethacrylate (PEGDMA), and 0.005 g of azobisisobutyronitrile (AIBN) were dissolved in 5 g of DME-1MLiTFSI electrolyte to obtain a blended electrolyte.

[0103] The battery was assembled with the blended electrodes of step (1) and step (2) and the blended electrolyte of step (3), and the assembled battery was placed in an oven at 80°C for curing for 24 hours to form a multilayer polymer electrolyte with ETPTA+PEGDMA on the positive electrode side and TEGDE polymer on the negative electrode side. The obtained battery was charged and discharged with a current of 0.1C for 2 cycles, and then charged and discharged with a current of 0.3C for 100 cycles.

[0104] Comparative Example 1

[0105] (1) The positive electrode slurry contains 50%wt of the solvent N-methylpyrrolidone and the solid component ratio is LiCo 0.1 Ni 0.8 Mn 0.1 O2: PVDF: conductive carbon black = 9:0.5:0.5; after coating and drying, the blended positive electrode is obtained.

[0106] (2) The negative electrode slurry contains 50%wt of the solvent N-methylpyrrolidone, and the solid component ratio is graphite: PVDF: conductive carbon black = 8:1:1; after coating and drying, a blended negative electrode is obtained.

[0107] (3) 0.3 g of polycarbonate diol (PCDL) with a molecular weight of 2000, 0.2 g of polyethylene glycol (PEG10000) with a molecular weight of 10000, and 0.1 g of toluene diisocyanate (TDI) were dissolved in 5 g of DME 1M LiTFSI electrolyte to obtain a blended electrolyte.

[0108] The battery was assembled with the blended electrodes of step (1) and (2) and the blended electrolyte of step (3), and the assembled battery was placed in an oven at 80°C for curing for 24 hours to obtain a solid-state battery. The obtained battery was charged and discharged for 2 cycles using a 0.1C current, and then charged and discharged for 100 cycles using a 0.3C current.

[0109] Comparative Example 2

[0110] (1) The positive electrode slurry contains 50%wt of the solvent N-methylpyrrolidone and the solid component ratio is LiCo 0.1 Ni 0.8 Mn 0.1 O2: PVDF: conductive carbon black = 9:0.5:0.5; after coating and drying, the blended positive electrode is obtained.

[0111] (2) The negative electrode slurry contains 50%wt of the solvent N-methylpyrrolidone, and the solid component ratio is graphite: PVDF: conductive carbon black = 8:1:1; after coating and drying, a blended negative electrode is obtained.

[0112] (3) 0.3 g of polycarbonate diol (PCDL) with a molecular weight of 2000, 0.2 g of lithium bis(fluorosulfonyl)imide (LiFSI), and 0.1 g of toluene diisocyanate (TDI) were dissolved in 5 g of an electrolyte of DME / DOL=1 / 1 1M LiTFSI to obtain a blended electrolyte.

[0113] The battery was assembled with the blended electrodes of step (1) and (2) and the blended electrolyte of step (3), and the assembled battery was placed in an oven at 80°C for curing for 24 hours to obtain a solid-state battery. The obtained battery was charged and discharged for 2 cycles using a 0.1C current, and then charged and discharged for 100 cycles using a 0.3C current.

[0114] Comparative Example 3

[0115] (1) The positive electrode slurry contains 50%wt of the solvent N-methylpyrrolidone and the solid component ratio is LiCo 0.1 Ni 0.8 Mn 0.1 O2: PVDF: conductive carbon black = 9:0.5:0.5; after coating and drying, the blended positive electrode is obtained.

[0116] (2) The negative electrode slurry contains 50%wt of the solvent N-methylpyrrolidone, and the solid component ratio is graphite: PVDF: conductive carbon black = 8:1:1; after coating and drying, a blended negative electrode is obtained.

[0117] (3) 0.3 g of polycarbonate diol (PCDL) with a molecular weight of 2000, 0.2 g of lithium bis(fluorosulfonyl)imide (LiFSI), 0.1 g of toluene diisocyanate (TDI), and 0.2 g of trimethylolpropane triglycidyl ether (TEGDE) were dissolved in 5 g of DME 1M LiTFSI electrolyte to obtain a blended electrolyte.

[0118] The battery was assembled with the blended electrodes of step (1) and (2) and the blended electrolyte of step (3), and the assembled battery was placed in an oven at 80°C for curing for 24 hours to obtain a solid-state battery. The obtained battery was charged and discharged for 2 cycles using a 0.1C current, and then charged and discharged for 100 cycles using a 0.3C current.

[0119] Comparative Example 4

[0120] (1) The positive electrode slurry contains 50%wt of the solvent N-methylpyrrolidone and the solid component ratio is LiCo 0.1 Ni 0.8 Mn 0.1 O2: PVDF: conductive carbon black = 9:0.5:0.5; after coating and drying, the blended positive electrode is obtained.

[0121] (2) The negative electrode slurry contains 50%wt of the solvent N-methylpyrrolidone, and the solid component ratio is graphite: PVDF: conductive carbon black = 8:1:1; after coating and drying, a blended negative electrode is obtained.

[0122] (3) 0.3 g of maleic anhydride (MA), 0.2 g of polyethylene glycol (PEG10000) with a molecular weight of 10,000, 0.1 g of toluene diisocyanate (TDI), 0.2 g of methyl methacrylate (MMA), and 0.002 g of azobisisobutyronitrile (AIBN) were dissolved in 5 g of DME 1M LiTFSI electrolyte to obtain a blended electrolyte.

[0123] The battery was assembled with the blended electrodes of step (1) and (2) and the blended electrolyte of step (3), and the assembled battery was placed in an oven at 80°C for curing for 24 hours to obtain a solid-state battery. The obtained battery was charged and discharged for 2 cycles using a 0.1C current, and then charged and discharged for 100 cycles using a 0.3C current.

[0124] Comparative Example 5

[0125] (1) The positive electrode slurry contains 50%wt of the solvent N-methylpyrrolidone and the solid component ratio is LiCo 0.1 Ni 0.8 Mn 0.1 O2: PVDF: conductive carbon black = 9:0.5:0.5; after coating and drying, the blended positive electrode is obtained.

[0126] (2) The negative electrode slurry contains 50%wt of the solvent N-methylpyrrolidone, and the solid component ratio is graphite: PVDF: conductive carbon black = 8:1:1; after coating and drying, a blended negative electrode is obtained.

[0127] (3) 0.5 g of ethoxylated trimethylolpropane triacrylate (ETPTA), 0.5 g of trimethylolpropane triglycidyl ether (TEGDE), 0.4 g of polyethylene glycol dimethacrylate (PEGDMA), and 0.005 g of azobisisobutyronitrile (AIBN) were dissolved in 5 g of DME 1M LiTFSI electrolyte to obtain a blended electrolyte.

[0128] The battery was assembled with the blended electrodes of step (1) and (2) and the blended electrolyte of step (3), and the assembled battery was placed in an oven at 80°C for curing for 24 hours to obtain a solid-state battery. The obtained battery was charged and discharged for 2 cycles using a 0.1C current, and then charged and discharged for 100 cycles using a 0.3C current.

[0129] Comparative Example 6

[0130] (1) The positive electrode slurry contains 50%wt of the solvent N-methylpyrrolidone and the solid component ratio is LiCo 0.1 Ni 0.8 Mn 0.1 O2: PVDF: conductive carbon black = 9:0.5:0.5; after coating and drying, the blended positive electrode is obtained.

[0131] (2) The negative electrode slurry contains 50%wt of the solvent N-methylpyrrolidone, and the solid component ratio is graphite: PVDF: conductive carbon black = 8:1:1; after coating and drying, a blended negative electrode is obtained.

[0132] (3) 0.5 g of polycarbonate diol (PCDL) with a molecular weight of 2000 and 0.1 g of toluene diisocyanate (TDI) were dissolved in 5 g of DME 1MLiTFSI to prepare a positive electrode coating liquid; 0.3 g of polyethylene glycol (PEG10000) with a molecular weight of 10000 and 0.1 g of toluene diisocyanate (TDI) were dissolved in 5 g of DME 1MLiTFSI to prepare a negative electrode coating liquid.

[0133] (4) The coating liquid obtained in step (3) is applied to the surfaces of the positive and negative electrodes respectively using a 50 μm scraper, and dried at 80° C. for 24 h to obtain a composite positive electrode and a composite negative electrode;

[0134] The composite electrode of step (3) (4) was cut into positive and negative electrodes of the battery, and the battery was assembled. Then, the battery was allowed to stand at 80°C for 5 hours to obtain a solid-state battery. The obtained battery was charged and discharged with a current of 0.1C for 2 cycles, and then charged and discharged with a current of 0.3C for 100 cycles.

[0135] Comparative Example 7

[0136] 1) 0.5 g of polycarbonate diol (PCDL) with a molecular weight of 2000 and 0.1 g of toluene diisocyanate (TDI) were mixed into the positive electrode slurry, wherein the positive electrode slurry contained 50% wt of solvent N-methylpyrrolidone and the solid component ratio was LiCo 0.1 Ni 0.8 Mn 0.1 O2: PVDF: conductive carbon black = 9:0.5:0.5; after coating and drying, continue to cure at 80°C for 24 hours to obtain a blended positive electrode.

[0137] (2) 0.3 g of polyethylene glycol (PEG10000) with a molecular weight of 10,000 and 0.1 g of toluene diisocyanate (TDI) were mixed into the negative electrode slurry, wherein the negative electrode slurry contained 50% wt of the solvent N-methylpyrrolidone and the solid component ratio was graphite: PVDF: conductive carbon black = 8:1:1; after coating and drying, the mixture was cured at 80°C for 24 hours to obtain a blended negative electrode.

[0138] (3) cutting the composite electrode of step (1) (2) into positive and negative electrodes of the battery, assembling the battery, injecting an electrolyte having a composition of DME 1MLiTFSI, and soaking for 24 hours to obtain a battery;

[0139] The obtained battery was charged and discharged with a current of 0.1C for 2 cycles, and then charged and discharged with a current of 0.3C for 100 cycles.

[0140] Comparative Example 8

[0141] (1) The positive electrode slurry contains 50%wt of the solvent N-methylpyrrolidone and the solid component ratio is LiCo 0.1 Ni 0.8 Mn 0.1 O2: PVDF: conductive carbon black = 9:0.5:0.5; after coating and drying, the blended positive electrode is obtained.

[0142] (2) The negative electrode slurry contains 50%wt of the solvent N-methylpyrrolidone, and the solid component ratio is graphite: PVDF: conductive carbon black = 8:1:1; after coating and drying, a blended negative electrode is obtained.

[0143] (3) 0.5 g of polycarbonate diol (PCDL) with a molecular weight of 2000 and 0.2 g of toluene diisocyanate (TDI) were dissolved in 5 g of DME 1MLiTFSI to prepare a positive electrode coating solution; 0.4 g of trimethylolpropane triglycidyl ether (TEGDE) and 1 g of lithium bis(fluorosulfonyl)imide (LiFSI) were dissolved in 5 g of DME 1MLiTFSI to prepare a negative electrode coating solution.

[0144] (4) The coating liquid obtained in step (3) is applied to the surfaces of the positive and negative electrodes respectively using a 50 μm scraper, and dried at 80° C. for 24 h to obtain a composite positive electrode and a composite negative electrode;

[0145] The composite electrode of step (3) (4) was cut into positive and negative electrodes of the battery, and the battery was assembled. Then, the battery was allowed to stand at 80°C for 5 hours to obtain a solid-state battery. The obtained battery was charged and discharged with a current of 0.1C for 2 cycles, and then charged and discharged with a current of 0.3C for 100 cycles.

[0146] Comparative Example 9

[0147] 1) 0.5 g of polycarbonate diol (PCDL) with a molecular weight of 2000 and 0.2 g of toluene diisocyanate (TDI) were mixed into the positive electrode slurry, wherein the positive electrode slurry contained 50% wt of solvent N-methylpyrrolidone and the solid component ratio was LiCo 0.1 Ni 0.8 Mn 0.1 O2: PVDF: conductive carbon black = 9:0.5:0.5; after coating and drying, continue to cure at 80°C for 24 hours to obtain a blended positive electrode.

[0148] (2) 0.4 g of trimethylolpropane triglycidyl ether and 1 g of lithium bis(fluorosulfonyl)imide (LiFSI) were mixed into the negative electrode slurry, wherein the negative electrode slurry contained 50% wt of the solvent N-methylpyrrolidone and the solid component ratio was graphite: PVDF: conductive carbon black = 8:1:1; after coating and drying, the mixture was cured at 80°C for 24 h to obtain a blended negative electrode.

[0149] (3) cutting the composite electrode of step (1) (2) into positive and negative electrodes of the battery, assembling the battery, injecting an electrolyte having a composition of DME 1MLiTFSI, and soaking for 24 hours to obtain a battery;

[0150] The obtained battery was charged and discharged with a current of 0.1C for 2 cycles, and then charged and discharged with a current of 0.3C for 100 cycles.

[0151] Comparative Example 10

[0152] (1) The positive electrode slurry contains 50%wt of the solvent N-methylpyrrolidone and the solid component ratio is LiCo 0.1 Ni 0.8 Mn 0.1 O2: PVDF: conductive carbon black = 9:0.5:0.5; after coating and drying, the blended positive electrode is obtained.

[0153] (2) The negative electrode slurry contains 50%wt of the solvent N-methylpyrrolidone, and the solid component ratio is graphite: PVDF: conductive carbon black = 8:1:1; after coating and drying, a blended negative electrode is obtained.

[0154] (3) 0.2 g of maleic anhydride (MA), 0.2 g of methyl methacrylate (MMA), and 0.004 g of azobisisobutyronitrile (AIBN) were dissolved in 5 g of DME 1MLiTFSI to prepare a positive electrode coating solution; 0.3 g of polyethylene glycol (PEG10000) with a molecular weight of 10,000 and 0.3 g of toluene diisocyanate (TDI) were dissolved in 5 g of DME 1MLiTFSI to prepare a negative electrode coating solution.

[0155] (4) The coating liquid obtained in step (3) is applied to the surfaces of the positive and negative electrodes respectively using a 50 μm scraper, and dried at 80° C. for 24 h to obtain a composite positive electrode and a composite negative electrode;

[0156] The composite electrode of step (3) (4) was cut into positive and negative electrodes of the battery, and the battery was assembled. Then, the battery was allowed to stand at 80°C for 5 hours to obtain a solid-state battery. The obtained battery was charged and discharged with a current of 0.1C for 2 cycles, and then charged and discharged with a current of 0.3C for 100 cycles.

[0157] Comparative Example 11

[0158] 1) 0.2 g maleic anhydride (MA), 0.2 g methyl methacrylate (MMA), and 0.004 g azobisisobutyronitrile (AIBN) were mixed into the positive electrode slurry, wherein the positive electrode slurry contained 50% wt of the solvent N-methylpyrrolidone and the solid component ratio was LiCo 0.1 Ni 0.8 Mn 0.1 O2: PVDF: conductive carbon black = 9:0.5:0.5; after coating and drying, continue to cure at 80°C for 24 hours to obtain a blended positive electrode.

[0159] (2) 0.3 g of polyethylene glycol (PEG10000) with a molecular weight of 10,000 and 0.3 g of toluene diisocyanate (TDI) were mixed into the negative electrode slurry, wherein the negative electrode slurry contained 50% wt of the solvent N-methylpyrrolidone and the solid component ratio was graphite: PVDF: conductive carbon black = 8:1:1; after coating and drying, the mixture was cured at 80°C for 24 hours to obtain a blended negative electrode.

[0160] (3) cutting the composite electrode of step (1) (2) into positive and negative electrodes of the battery, assembling the battery, injecting an electrolyte having a composition of DME 1MLiTFSI, and soaking for 24 hours to obtain a battery;

[0161] The obtained battery was charged and discharged with a current of 0.1C for 2 cycles, and then charged and discharged with a current of 0.3C for 100 cycles.

[0162] The test results of the above embodiments and comparative examples are shown in Tables 1 and 2.

[0163] Table 1 Battery performance test results of the embodiment

[0164]

[0165]

[0166] Table 2 Performance test results of the batteries in the comparative examples

[0167]

[0168] By comparing Examples 1-5, it can be seen that the in-situ multilayer structure electrolyte prepared using cross-linked structure monomers has better cycle stability than the non-cross-linked structure.

[0169] It can be seen from the battery cycle data of Examples 1-5 and Comparative Examples 1-5 that the battery prepared by the in-situ curing multilayer structure has significantly better cycle performance than the battery prepared by the traditional in-situ polymerization method;

[0170] By comparing the three groups of data, Example 1, Comparative Example 6, Comparative Example 7 ( Figure 1 ), Example 3, Comparative Example 8, Comparative Example 9 ( Figure 2 ), Example 4, Comparative Example 10, Comparative Example 11 ( Figure 3 ), it can be seen that the in-situ multilayer structure has better capacity and cycle stability than the traditional multilayer structure prepared by coating on the surface of the electrode and simple mixing. This is because the electrolyte prepared by in-situ polymerization inside the battery cell is an integrated interconnected structure of positive and negative electrodes, while there is an interface between the composite positive electrode and the electrolyte after simple positive and negative electrode coating and mixing, so the ion conductivity is poor.

[0171] According to Tables 1-2, the methods in Comparative Examples 1-5 do not pre-place different monomers at the positive and negative electrodes respectively, and thus cannot form different polymer structures at the positive and negative electrodes respectively, resulting in poor cycle performance of the battery.

[0172] Comparative Examples 6, 8 and 10 all adopt the method of direct coating on the electrode surface. Although this method can also form different polymer structures on the surface of the positive and negative electrodes, there is an obvious interface between the positive and negative electrode materials and the solid electrolyte, and there is also an obvious interface between the positive electrode solid electrolyte and the negative electrode solid electrolyte and the electrolyte, resulting in poor cycle performance and capacity.

[0173] The solutions of Comparative Examples 7, 9 and 11 are all to mix different polymerization systems into the positive and negative electrode slurries respectively. Although this solution also forms different polymer structures at the positive and negative electrodes, and there is no obvious interface between the positive electrode material and the solid electrolyte, and between the negative electrode material and the solid electrolyte, there is an obvious interface between the positive electrode solid electrolyte, the negative electrode solid electrolyte and the electrolyte, resulting in poor cycle performance.

[0174] It can be seen from the test data in the above embodiments and comparative examples and Tables 1 to 2 that the battery prepared by the method of the present invention has no obvious interface between the positive electrode material, the positive electrode solid electrolyte, the electrolyte, the negative electrode solid electrolyte, and the negative electrode material, and has better capacity performance and cycle performance.

[0175] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An in-situ polymerized solid-state battery having a multilayer structure electrolyte, wherein the multilayer structure electrolyte comprises an oxidation-resistant polymer layer formed in-situ on the positive electrode side and a reduction-resistant polymer layer formed in-situ on the negative electrode side; The in-situ polymerization solid-state battery with a multilayer structure electrolyte is prepared according to the following steps: A) mixing the first pre-set monomer with the positive electrode slurry, and coating to obtain a composite positive electrode; mixing the second pre-set monomer with the negative electrode slurry, and coating to obtain a composite negative electrode; B) assembling a battery cell using the composite positive electrode and the composite negative electrode; C) injecting electrolyte into the battery core to initiate monomer polymerization to form a multilayer structure electrolyte; The electrolyte contains a first reactive monomer and a second reactive monomer; The first pre-set monomer reacts chemically with the first reactive monomer in the electrolyte to generate an oxidation-resistant polymer; the second pre-set monomer reacts chemically with the second reactive monomer in the electrolyte to generate a reduction-resistant polymer; The first pre-set monomer is a first polymer monomer or a first initiator; The second pre-set monomer is a second polymer monomer or a second initiator.

2. The in-situ polymerized solid-state battery with a multilayer electrolyte according to claim 1, characterized in that: The mass fraction of the first pre-set monomer in the positive electrode slurry is 0.01-35%; the mass fraction of the second pre-set monomer in the negative electrode slurry is 0.01-35%.

3. The in-situ polymerized solid-state battery with a multilayer electrolyte according to claim 1, characterized in that: The mass fraction of the first reaction monomer in the electrolyte is 0.01-50%; the mass fraction of the second reaction monomer in the electrolyte is 0.01-50%.

4. The in-situ polymerized solid-state battery with a multilayer electrolyte according to claim 1 or 2, characterized in that: The first polymer monomer includes one or more of ester monomers, carbonate monomers, sulfone monomers, isocyanates, amide monomers, nitrile monomers and fluorinated monomers; The first initiator includes one or more of an azo initiator, a peroxide initiator, an anionic and cationic initiator, an organic metal compound initiator, an amine catalyst initiator and an organic phosphorus initiator.

5. The in-situ polymerized solid-state battery with a multilayer electrolyte according to claim 4, characterized in that: The first polymer monomer includes vinyl acetate, dimethyl allyl dicarboxylate, diethyl allyl malonate, methallyl carbonate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, methyl methacrylate, butyl methacrylate, vinylene carbonate, vinyl ethylene carbonate, methyl vinyl sulfone, ethyl vinyl sulfone, vinyl acetate, 1,4-butanediol ester diol, polycarbonate diol, polyethylene adipate diol, ethoxylated trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, One or more of dipentaerythritol hexaacrylate, acrylamide, N,N-methylenebisacrylamide, N-methylmaleamide, N-ethylmaleamide, caprolactam, butyrolactam, maleic anhydride, acrylonitrile, 2-cyanoethyl acrylate, 2-cyano-2-butyl acrylate, 2-cyano-3,3-diphenylacrylate isooctyl ester, 1-cyclohexeneacetonitrile, hexafluorobutyl methacrylate, trifluoroethyl methacrylate, dihydroxyethyl terephthalate, toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate and hexamethylene diisocyanate.

6. The in-situ polymerized solid-state battery with a multilayer electrolyte according to claim 4, characterized in that: The first initiator includes one or more of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, benzoyl peroxide, tert-butyl benzoyl peroxide, methyl ethyl ketone peroxide, stannous octoate, lithium acetate, triethyl phosphine, triphenyl phosphine, tri-n-butyl phosphine, tributyltin oxide, tetrabutyl titanate, tetrabutyl zirconate, trialkyltin alkoxide, dialkyltin oxide, N-methylethylenediamine, dimethylformamide, triethyleneethylenediamine, methyldiethylene glycolamine, triethylenediamine, aluminum trifluoromethylsulfonate, magnesium trifluoromethylsulfonate, lithium bis(fluorosulfonyl)imide and tin trifluoromethylsulfonate.

7. The in-situ polymerized solid-state battery with a multilayer electrolyte according to claim 1 or 2, characterized in that: The second polymer monomer includes one or more of an ether compound, an ether segment-containing oligomer and a siloxane; The second initiator includes one or more of an azo initiator, a peroxide initiator, an anionic and cationic initiator, an organic metal compound initiator, an amine catalyst initiator and an organic phosphorus initiator.

8. The in-situ polymerized solid-state battery with a multilayer electrolyte according to claim 7, characterized in that: The second polymer monomer includes one or more of polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, ethoxyethoxyethyl acrylate, polyethylene glycol, 1,3-dioxolane, dioxane, hydroxy polyether silicone oil, polytetramethylene ether glycol, vinyl methoxysilane, 2-(trimethylsiloxy)ethyl methacrylate, trivinylcyclotrisiloxane, tri(2-methoxyethoxy)vinyl silane, octahydroxypropyldimethylsilyl-POSS, polyether amine, and trihydroxymethylpropane triglycidyl ether.

9. The in-situ polymerized solid-state battery with a multilayer electrolyte according to claim 7, characterized in that: The second initiator includes one or more of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, benzoyl peroxide, tert-butyl benzoyl peroxide, methyl ethyl ketone peroxide, stannous octoate, lithium acetate, triethyl phosphine, triphenyl phosphine, tri-n-butyl phosphine, tributyltin oxide, tetrabutyl titanate, tetrabutyl zirconate, trialkyltin alkoxide, dialkyltin oxide, N-methylethylenediamine, dimethylformamide, triethyleneethylenediamine, methyldiethylene glycolamine, triethylenediamine, aluminum trifluoromethylsulfonate, magnesium trifluoromethylsulfonate, lithium bis(fluorosulfonyl)imide and tin trifluoromethylsulfonate.

10. A method for preparing an in-situ polymerized solid-state battery having a multilayer electrolyte as claimed in any one of claims 1 to 9, comprising the following steps: A) mixing the first pre-set monomer with the positive electrode slurry, and coating to obtain a composite positive electrode; mixing the second pre-set monomer with the negative electrode slurry, and coating to obtain a composite negative electrode; B) assembling a battery cell using the composite positive electrode and the composite negative electrode; C) injecting electrolyte into the battery core to initiate monomer polymerization to form a multilayer structure electrolyte; The electrolyte contains a first reactive monomer and a second reactive monomer; The first pre-set monomer reacts chemically with the first reactive monomer in the electrolyte to generate an oxidation-resistant polymer; the second pre-set monomer reacts chemically with the second reactive monomer in the electrolyte to generate a reduction-resistant polymer.

11. The preparation method according to claim 10, characterized in that: The step C) initiates polymerization by heating; the heating temperature is 25 to 90° C.; and the heating time is 1 to 120 hours.

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