A gel electrolyte, a secondary battery containing the same, and a method for preparing the same

Abstract

The application belongs to the field of batteries, and specifically discloses a gel electrolyte, a secondary battery containing the same and a preparation method of the secondary battery. The polymer in the gel electrolyte is obtained by polymerization of a monomer containing a terminal acrylate group polyglycidyl ether nitrate, so that a nitro group exists in the polymer skeleton, which is beneficial to the formation of stable CEI and SEI at the interfaces of the positive electrode and the negative electrode respectively, and is beneficial to the improvement of the electrochemical stability and the lithium ion transmission performance at the interfaces, thereby achieving the purpose of improving the electrochemical window, the cycle stability and the coulombic efficiency of the battery.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of batteries, and particularly relates to a gel electrolyte, a secondary battery containing the same and a preparation method thereof. BACKGROUND

[0002] Traditional liquid electrolyte has safety hazards such as easy leakage, flammability and explosiveness, which has become the main bottleneck for the development of high-energy-density lithium-ion batteries. In contrast, solid-state electrolytes have attracted widespread attention from academia and industry due to their ability to simultaneously improve safety and energy density. According to the composition difference, solid-state electrolytes can be divided into four categories: inorganic ceramics, polymers, composites and gels. Among them, gel electrolyte, which has high safety and excellent interface compatibility, has become a research hotspot. It is particularly noteworthy that gel electrolyte prepared by in-situ polymerization process can seamlessly connect the existing liquid battery production line, providing a highly competitive technical path for large-scale industrialization.

[0003] At present, in-situ polymerized electrolytes mainly include polyether, polyacrylate and polyurethane. Among them, polyether-based electrolytes such as polydioxolane are often prepared by thermal initiation or chemical initiator to initiate ring-opening polymerization of cyclic ethers, resulting in electrolytes with good interface performance; polyurethane-based electrolytes are mostly prepared by reaction between isocyanate and monomers containing active hydrogen, which can form gel electrolytes. Polyacrylate electrolytes use methyl methacrylate (MMA) and other monomers as monomers, and are prepared by free radical polymerization or cationic polymerization method, which has excellent mechanical properties and chemical stability; and the in-situ polymerization method using free radical polymerization has good wettability, controllable polymerization conditions and shorter polymerization time, which has attracted widespread attention from the industry.

[0004] At present, the electrochemical stability of the polymer skeleton formed by several in-situ polymerized electrolytes is often poor, and it is also prone to side reactions with the positive and negative electrodes of the battery. For example, polyether systems have poor oxidation resistance, polyurethane electrolytes have poor stability on both positive and negative electrodes, and polyacrylate electrolytes have poor stability on the negative electrode. In addition, in-situ polymerized electrolytes must face the hidden risk of "residual monomers" in practical application. For example, unconverted cyclic ethers (such as DOL) or acrylate monomers are prone to oxidation and decomposition at high temperature and high voltage, generating gas or oligomers, which not only leads to battery swelling and capacity diving, but also induces side reactions at the battery interface. Therefore, how to improve the stability of in-situ polymerized electrolytes and further improve the electrochemical window, initial efficiency and cycle stability of the battery is one of the focuses of in-situ polymer electrolyte batteries at present. SUMMARY

[0005] In view of the problems of the prior art that the in-situ polymer electrolyte leads to poor electrochemical window, initial efficiency and cycle stability of the battery containing the same, the present application provides a gel electrolyte, a secondary battery containing the same and a preparation method thereof.

[0006] To achieve the above object, the specific technical solutions include the following:

[0007] In a first aspect, the present application provides a gel electrolyte, comprising a polymer obtained by polymerization of monomer A itself, and / or a polymer obtained by polymerization of monomer A and monomer B.

[0008] The monomer A comprises a compound represented by general chemical structure (I):

[0009] ,

[0010] n is an integer from 1 to 100.

[0011] The compound represented by general chemical structure (I) is a terminal acrylate group polyglycidyl ether nitrate, which is used as one of the monomers A for polymerization to form a gel electrolyte. The monomer A is polymerized by itself or with a double bond in another type of vinyl monomer B through free radical addition polymerization to generate a random copolymer with a saturated C-C bond as the main chain, forming a polymer in the gel electrolyte, so that there is a nitro group in the polymer skeleton. The presence of the nitro group can decompose at the negative electrode to form a stable SEI rich in lithium nitride, which is conducive to the transmission of lithium ions at the negative electrode interface, thereby improving the coulomb efficiency and cycle life of the battery. It is also conducive to the formation of a stable CEI on the positive electrode surface, and it can effectively improve the electrochemical window and oxidation resistance of the electrolyte, thereby improving the cycle stability of the battery.

[0012] Preferably, the preparation method of the compound represented by general chemical structure (I) comprises the following steps: mixing polyglycidyl ether nitrate, triethylamine, acryloyl chloride and a solvent, and reacting at -10-5°C to obtain a terminal acrylate group polyglycidyl ether nitrate.

[0013] Preferably, the monomer B comprises other vinyl monomers in addition to the monomer A.

[0014] Preferably, the monomer B comprises at least one of an acrylate monomer, a nitrile group-containing vinyl monomer, an amide group-containing vinyl monomer, a sulfone group-containing vinyl monomer, a styrene monomer or an ester group-containing vinyl monomer.

[0015] The ester group-containing vinyl monomer herein does not include an acrylate monomer.

[0016] Preferably, the monomer B includes at least one of polyethylene glycol diacrylate, polyethylene glycol acrylate, polyethylene glycol dimethacrylate, poly(ethylene glycol) methyl methacrylate, methyl acrylate, acryloyl isocyanate, methacrylate, trifluoroethyl methacrylate, hexafluorobutyl methacrylate, dimethyl allyl dicarboxylate, diethyl allyl malonate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, ethoxylated trimethylolpropane triacrylate, acrylonitrile, acrylamide, N,N-methylenebis(acrylamide), methyl vinyl sulfone, ethyl vinyl sulfone, vinyl acetate, styrene, 4-fluorostyrene, 3-fluorostyrene, 3,4-difluorostyrene, pentafluorostyrene, vinylene carbonate, or vinyl ethylene carbonate.

[0017] Preferably, the mass percentage of the monomer A is 0.1%-30%, further preferably 2%-20%, and the mass percentage of the monomer B is 0%-50%, further preferably 1-40%, based on the mass of the gel electrolyte.

[0018] Preferably, the mass ratio of the monomer A to the monomer B is (0.5-5):1, further preferably (1-4):1.

[0019] Preferably, the polymerization is independently selected to be performed in the presence of an initiator including at least one of azobisisobutyronitrile, cyclohexanone peroxide, azobisisoheptane nitrile, t-butyl hydroperoxide, or dimethyl azobis isobutyrate, and the mass percentage of the initiator is 0.01%-5%, based on the mass of the gel electrolyte.

[0020] Preferably, the gel electrolyte further includes a solvent and a lithium salt.

[0021] Further preferably, the mass percentage of the lithium salt is 5%-60%, and the mass percentage of the solvent is 0.1%-95%, based on the mass of the gel electrolyte.

[0022] Preferably, the lithium salt includes at least one of lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethylsulfonyl)imide, lithium bisfluorosulfonylimide, lithium tetrafluoroborate, lithium difluoro oxalato borate (LiDFOB), lithium difluoro di oxalato phosphate, lithium bis oxalate borate, lithium trifluoromethylsulfonate, lithium tetrafluoroaluminate, lithium 4,5-dicyano-2-trifluoromethylimidazole, lithium hexafluoroarsenate, lithium perchlorate, lithium difluorophosphate, or lithium nitrate.

[0023] Preferably, the solvent comprises at least one of ethylene carbonate, fluoroethylene carbonate, vinyl ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl trifluoroethyl carbonate, butylene carbonate, methyl propyl carbonate, methyl formate, ethyl formate, propyl formate, butyl formate, ethyl acetate, ethyl difluoroacetate, ethyl trifluoroacetate, propyl acetate, butyl acetate, methyl propionate, methyl trifluoro propionate, ethyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, δ-valerolactone, 2-methyl tetrahydrofuran, 4-methyl-1,3-dioxolane, 2-methyl-1,3-dioxolane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, butyrolactone, hexalactone, fluoroacetonitrile, ethylene sulfate, hexaphenoxycyclotriphosphazene, hexafluorotriphosphazene, ethoxy pentafluorocyclotriphosphazene, tricresyl phosphate, trimethyl phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate, or cresyl diphenyl phosphate.

[0024] Preferably, the gel electrolyte further comprises inorganic particles.

[0025] Further preferably, the particle size of the inorganic particles is 10-100 nm.

[0026] Further preferably, the inorganic particles comprise at least one of titanium dioxide, di-aluminum trioxide, zirconium oxide, nickel oxide, silicon nitride, lithium lanthanum titanate, lithium lanthanum zirconium oxide, lithium titanium phosphate, silicon dioxide and / or aerogel powder thereof, sulfide solid electrolyte material, garnet solid electrolyte material, perovskite solid electrolyte material, NASICON solid electrolyte material, halide solid electrolyte material. The presence of inorganic particles in the electrolyte can further improve the initial efficiency and cycle stability of the battery.

[0027] Preferably, the mass percentage of the inorganic particles is 0.01%-9%, further preferably 0.05-5%, based on the mass of the gel electrolyte.

[0028] In a second aspect, the present application provides a secondary battery comprising a positive electrode sheet, a negative electrode sheet, a separator, and the gel electrolyte.

[0029] In a third aspect, the present application provides a preparation method of the secondary battery, comprising the following steps:

[0030] S1, mixing monomer A, optional monomer B, and other optional raw materials to obtain a gel electrolyte precursor;

[0031] S2, stacking the positive electrode sheet, the separator, and the negative electrode sheet to obtain a dry cell;

[0032] S3, injecting the gel electrolyte precursor into the dry battery cell, sequentially standing, polymerization reaction, to obtain the secondary battery.

[0033] The monomer and the remaining raw materials are mixed to obtain a gel electrolyte precursor, which is directly placed in a dry battery cell, and the gel electrolyte is formed by in-situ polymerization.

[0034] Preferably, the standing time is 5-48h.

[0035] Preferably, the polymerization reaction temperature is 30-80℃, and the polymerization time is 10-48h.

[0036] Preferably, the positive electrode sheet comprises 10-95% of the positive active material by mass percentage, and the positive active material comprises at least one of lithium cobaltate, lithium nickel cobaltate, lithium manganate, lithium nickel manganate, ternary lithium nickel cobalt manganate, lithium nickel cobalt aluminum, lithium nickel cobalt manganese aluminum, lithium manganese iron phosphate, lithium iron phosphate, sulfur or lithium sulfide.

[0037] Preferably, the negative electrode sheet comprises 10-95% of the negative active material by mass percentage, and the negative active material comprises at least one of lithium metal, lithium metal alloy, hard carbon, molybdenum disulfide, lithium niobate, lithium titanate, lithium titanium niobate, graphite, silicon, silicon oxide, silicon carbon or silicon oxygen carbon.

[0038] Preferably, the positive electrode sheet and / or the negative electrode sheet further comprises components with the following mass percentage: 0.1-10% of the binder, 0.1-10% of the conductive agent.

[0039] Preferably, the separator comprises at least one of polypropylene (PP), polyethylene (PE), polyamide (PI), cellulose membrane, polyethylene terephthalate (PET) porous membrane and ceramic coated membrane.

[0040] Preferably, the binder comprises at least one of carboxymethyl cellulose, sodium carboxymethyl cellulose, butyl benzene emulsion, and polyvinylidene fluoride (PVDF).

[0041] Preferably, the conductive agent comprises at least one of conductive carbon black and carbon nanotubes (CNT).

[0042] Compared with the prior art, the present application has the following beneficial effects: the polymer in the gel electrolyte of the present application is obtained by polymerization of a monomer containing a terminal acrylate group polyglycidyl ether nitrate, so that there is a nitro group in the polymer skeleton, which is conducive to the formation of stable CEI and SEI at the interfaces of the positive and negative electrodes, respectively, and is conducive to improving the electrochemical stability and lithium ion transmission performance at the interface, thereby achieving the purpose of improving the electrochemical window, cycle stability and coulombic efficiency of the battery. DETAILED DESCRIPTION

[0043] In order to better illustrate the purpose, technical scheme and advantages of the present application, the present application will be further described below through specific examples. The test methods used in the examples and / or comparative examples are all conventional methods unless otherwise specified; the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0044] The terminal acrylate group polyglycidyl ether nitrate can be commercially purchased or self-made.

[0045] The terminal acrylate group polyglycidyl ether nitrate used in the following examples is obtained by the following method, specifically comprising the following steps:

[0046] (1) Glycidyl ether nitrate (GN) preparation: In a 150 mL three-necked round-bottom flask, 30 mL of anhydrous CH2Cl2 and 20.4 g of acetic anhydride (0.2 mol) were added, and the flask was placed in an ice-salt bath, stirred, and cooled to -10°C. 12.6 g of concentrated nitric acid (0.2 mol) was slowly added dropwise, and the dropping speed was controlled (about 1 drop / s), and the reaction temperature was kept ≤-5°C. After the addition was completed, the stirring was continued for 10 min. 14.8 g of glycidol (0.2 mol) was dissolved in 20 mL of anhydrous CH2Cl2, and was slowly added dropwise into the above nitration system, and the dropping speed was controlled (about 1 drop / s), and the reaction temperature was kept at -10±2°C. The dropping time was about 30 min, and after the addition was completed, the low-temperature reaction was continued for 30 min. After the reaction was completed, the reaction mixture was slowly poured into 50 mL of ice water to quench, stirred for 5 min, and the organic phase was separated by a separatory funnel. The organic phase was washed with saturated NaHCO3 solution until neutral (pH 7), and then washed with water twice, and dried with anhydrous MgSO4 for 30 min. The solvent was removed by concentration under reduced pressure (40°C), and the GN was collected by reduced pressure distillation (70-75°C, 1 mmHg).

[0047] (2) Preparation of polyglycidyl ether nitrate: In a dry four-necked flask, 1,4-butanediol (0.189 g, 2.1 mmol) and a small amount of CaH2 (dehydrated) were added, and stirred under nitrogen protection. BF3·THF (0.294 g, 2.1 mmol) was slowly added dropwise, and the reaction was carried out at room temperature for 30-60 min. GN (10 g, 84 mmol) was dissolved in an equal volume of anhydrous CH2Cl2, and was slowly added dropwise into the above catalyst system through a constant-pressure dropping funnel, and the dropping speed was controlled, and the dropping time was controlled for 5 hours. After the addition was completed, the stirring was continued for 1 hour, and methanol (MeOH) was added to quench the reaction, and the organic phase was washed with saturated NaHCO3 solution, and the solvent was removed by rotary evaporation, and the polyglycidyl ether nitrate was obtained as a light yellow viscous liquid.

[0048] (3) Preparation of terminal acrylate group polyglycidyl ether nitrate:

[0049] In a reactor equipped with a mechanical stirring device, 5 g of polyglycidyl ether nitrate was added, 500 ml of dichloromethane and (7.47 g, 73.8 mmol) of triethylamine were added. Then, the ice salt bath was cooled to 0°C, 80 ml of dichloromethane solution containing (4.94 g, 54.4 mmol) of acryloyl chloride was added dropwise, and the dropwise time was 6 h. After the dropwise addition was completed, the reaction was continued for 24 h, the reaction liquid was washed with water until it was neutral, and the oil phase was concentrated under reduced pressure to remove the solvent to obtain a terminal acrylate group polyglycidyl ether nitrate (Mn is about 700).

[0050] Example 1

[0051] A preparation method of a lithium battery, comprising the following steps:

[0052] S1, under the condition that the concentration of water and oxygen is less than 0.1 ppm, 0.5 g of terminal acrylate group polyglycidyl ether nitrate, 0.5 g of polyethylene glycol diacrylate (Mn=600), 0.114 g of LiDFOB, 10 g of 1M LiPF6 (EC / EMC, 3 / 7, v / v) and 0.02 g of azobisisobutyronitrile (AIBN) are uniformly mixed, and stirred at room temperature to obtain a gel electrolyte precursor.

[0053] S2, the positive electrode sheet includes a positive electrode material coating layer composed of commercial high-nickel ternary positive electrode active material (NCM811, same below), PVDF and single-walled CNT mixed in a mass ratio of 9:0.5:0.5; the negative electrode sheet includes a negative electrode material coating layer composed of commercial silicon-carbon 550 negative electrode active material, sodium carboxymethyl cellulose (CMC), butadiene rubber latex (SBR) and single-walled CNT mixed in a mass ratio of 9:0.25:0.25:0.5. The positive electrode sheet and the negative electrode sheet are made into a dry cell in the form of a laminated sheet, and after the dry cell is baked, 15 g of the above-mentioned precursor is injected into a 10 Ah dry cell, and the dry cell is placed at room temperature for 10 h.

[0054] S3, the cell is cured at 45°C for 6 h, and then cured at 60°C for 2 h to obtain an in-situ polymerized electrolyte lithium metal battery.

[0055] Example 2

[0056] A preparation method of a lithium battery, comprising the following steps:

[0057] S1, under the condition that the concentration of water and oxygen is less than 0.1 ppm, 0.5 g of terminal acrylate group polyglycidyl ether nitrate, 0.5 g of polyethylene glycol diacrylate (Mn=600), 0.114 g of LiDFOB, 10 g of 1M LiPF6 (EC / EMC, 3 / 7, v / v) and 0.02 g of azobisisobutyronitrile (AIBN) are uniformly mixed, and stirred at room temperature to obtain a gel electrolyte precursor.

[0058] S2, the positive electrode tab includes a positive electrode material coating layer composed of a commercial high-nickel ternary positive electrode active material, PVDF and single-walled CNTs at a mass ratio of 9:0.5:0.5; the negative electrode tab includes a negative electrode material coating layer, and the negative electrode material is composed of a commercial silicon-carbon 550 negative electrode active material, sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber latex (SBR) and single-walled CNTs at a mass ratio of 9:0.25:0.25:0.5. The positive electrode tab and the negative electrode tab are made into a dry cell in a laminated form, and after the dry cell is baked, 15g of the above precursor is injected into a 10Ah dry cell, and the dry cell is left to stand at room temperature for 10h.

[0059] S3, the cell is cured at 45°C for 6h, and then cured at 60°C for 2h to obtain an in-situ polymerized electrolyte lithium metal battery.

[0060] Example 3

[0061] A preparation method of a lithium battery, comprising the following steps:

[0062] S1, under the condition that the water and oxygen concentration is less than 0.1ppm, 0.5g of acrylate-terminated polyglycidyl ether nitrate, 1.5g of methyl methacrylate, 0.114g of LiDFOB, 10g of 1M LiPF6 (EC / EMC, 3 / 7, v / v) and 0.02g of azobisisobutyronitrile (AIBN) are uniformly mixed, and stirred at room temperature to obtain a gel electrolyte precursor.

[0063] S2, the positive electrode tab includes a positive electrode material coating layer composed of a commercial high-nickel ternary positive electrode active material, PVDF and single-walled CNTs at a mass ratio of 9:0.5:0.5; the negative electrode tab includes a negative electrode material coating layer, and the negative electrode material is composed of a commercial silicon-carbon 550 negative electrode active material, sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber latex (SBR) and single-walled CNTs at a mass ratio of 9:0.25:0.25:0.5. The positive electrode tab and the negative electrode tab are made into a dry cell in a laminated form, and after the dry cell is baked, 15g of the above precursor is injected into a 10Ah dry cell, and the dry cell is left to stand at room temperature for 10h.

[0064] S3, the cell is cured at 45°C for 6h, and then cured at 60°C for 2h to obtain an in-situ polymerized electrolyte lithium metal battery.

[0065] Example 4

[0066] A preparation method of a lithium battery, comprising the following steps:

[0067] S1, 0.5 g of end-acrylate polyglycidyl ether nitrate, 1.5 g of styrene, 0.114 g of LiDFOB, 10 g of 1M LiPF6 (EC / EMC, 3 / 7, v / v), and 0.02 g of azobisisobutyronitrile (AIBN) were uniformly mixed under the condition that the concentration of water and oxygen was less than 0.1 ppm, and stirred at room temperature to obtain a gel electrolyte precursor.

[0068] S2, the positive electrode tab includes a positive electrode material coating layer composed of a commercial high-nickel ternary positive electrode active material, PVDF and single-walled CNT at a mass ratio of 9:0.5:0.5; the negative electrode tab includes a negative electrode material coating layer, and the negative electrode material is composed of a commercial silicon-carbon 550 negative electrode active material, sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber latex (SBR) and single-walled CNT at a mass ratio of 9:0.25:0.25:0.5. The positive electrode tab and the negative electrode tab are made into a dry cell in a laminated form, and after the dry cell is baked, 15 g of the above-mentioned precursor is injected into a 10 Ah dry cell, and the dry cell is left to stand at room temperature for 10 h.

[0069] S3, the cell is cured at 45°C for 6 h, and then cured at 60°C for 2 h to obtain an in-situ polymerized electrolyte lithium metal battery.

[0070] Example 5

[0071] A preparation method of a lithium battery, comprising the following steps:

[0072] S1, 0.5 g of end-acrylate polyglycidyl ether nitrate, 1.5 g of styrene, 0.114 g of LiDFOB, 10 g of 1M LiPF6 (EC / EMC, 3 / 7, v / v), and 0.02 g of azobisisobutyronitrile (AIBN) were uniformly mixed under the condition that the concentration of water and oxygen was less than 0.1 ppm, and stirred at room temperature to obtain a gel electrolyte precursor.

[0073] S2, the positive electrode tab includes a positive electrode material coating layer composed of a commercial high-nickel ternary positive electrode active material, PVDF and single-walled CNT at a mass ratio of 9:0.5:0.5; the negative electrode tab includes a negative electrode material coating layer, and the negative electrode material is composed of a commercial silicon-carbon 550 negative electrode active material, sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber latex (SBR) and single-walled CNT at a mass ratio of 9:0.25:0.25:0.5. The positive electrode tab and the negative electrode tab are made into a dry cell in a laminated form, and after the dry cell is baked, 15 g of the above-mentioned precursor is injected into a 10 Ah dry cell, and the dry cell is left to stand at room temperature for 10 h.

[0074] S3, the cell is cured at 45°C for 6 h, and then cured at 60°C for 2 h to obtain an in-situ polymerized electrolyte lithium metal battery.

[0075] Example 6

[0076] A preparation method of a lithium battery, comprising the following steps:

[0077] S1, under the condition that the oxygen concentration is less than 0.1 ppm, 0.5 g of end-acrylate polyglycidyl ether nitrate, 0.5 g of polyethylene glycol diacrylate (Mn=600), 0.01 g of nano-silicon dioxide (D50=30 nm), 0.114 g of LiDFOB, 10 g of 1M LiPF6 (EC / EMC, 3 / 7, v / v) and 0.02 g of azobisisobutyronitrile (AIBN) are uniformly mixed, and stirring is carried out at room temperature to obtain a gel electrolyte precursor.

[0078] S2, the positive electrode sheet comprises a positive electrode material coating layer composed of commercial high-nickel ternary positive electrode active material, PVDF and single-walled CNT at a mass ratio of 9:0.5:0.5; the negative electrode sheet comprises a negative electrode material coating layer composed of commercial silicon-carbon 550 negative electrode active material, sodium carboxymethyl cellulose (CMC), butadiene rubber latex (SBR) and single-walled CNT at a mass ratio of 9:0.25:0.25:0.5. The positive electrode sheet and the negative electrode sheet are made into a dry cell in the form of a laminated sheet, and after the dry cell is baked, 15 g of the above-mentioned precursor is injected into a 10 Ah dry cell, and the dry cell is placed at room temperature for 10 h.

[0079] S3, the cell is cured at 45℃ for 6h, and then cured at 60℃ for 2h to obtain an in-situ polymerized electrolyte lithium metal battery.

[0080] Example 7

[0081] The difference between this example and Example 3 is that 1.5 g of methyl methacrylate is replaced by an equal amount of acrylonitrile in this example, and the rest is the same.

[0082] Example 8

[0083] The difference between this example and Example 3 is that 1.5 g of methyl methacrylate is replaced by an equal amount of N,N-methylenebis(acrylamide) in this example, and the rest is the same.

[0084] Example 9

[0085] The difference between this example and Example 3 is that 1.5 g of methyl methacrylate is replaced by an equal amount of methyl vinyl sulfone in this example, and the rest is the same.

[0086] Example 10

[0087] The difference between this example and Example 3 is that 1.5 g of methyl methacrylate is replaced by an equal amount of vinyl acetate in this example, and the rest is the same.

[0088] Example 11

[0089] A preparation method of a lithium battery, comprising the following steps:

[0090] S1, under the condition that the water and oxygen concentration is less than 0.1 ppm, 1 g of end-acrylate polyglycidyl ether nitrate, 0.114 g of LiDFOB, 10 g of 1M LiPF6 (EC / EMC, 3 / 7, v / v) and 0.02 g of azobisisobutyronitrile (AIBN) are uniformly mixed and stirred at room temperature to obtain a gel electrolyte precursor.

[0091] S2, the positive electrode tab includes a positive electrode material coating layer composed of commercial high-nickel ternary positive electrode active material, PVDF and single-walled CNT at a mass ratio of 9:0.5:0.5; the negative electrode tab includes a negative electrode material coating layer, and the negative electrode material is composed of commercial silicon-carbon 550 negative electrode active material, sodium carboxymethyl cellulose (CMC), butadiene rubber latex (SBR) and single-walled CNT at a mass ratio of 9:0.25:0.25:0.5. The positive electrode tab and the negative electrode tab are made into a dry cell in the form of a laminated sheet, and after the dry cell is baked, 15 g of the above-mentioned precursor is injected into a 10 Ah dry cell, and the dry cell is placed at room temperature for 10 h.

[0092] S3, the cell is cured at 45°C for 6h, and then cured at 60°C for 2h to obtain an in-situ polymerized electrolyte lithium metal battery.

[0093] Comparative Example 1

[0094] This comparative example is compared with Example 1, and the comparative example lacks end-acrylate polyglycidyl ether nitrate monomer, and specifically comprises the following steps:

[0095] S1, under the condition that the water and oxygen concentration is less than 0.1 ppm, 1 g of end-acrylate polyglycidyl ether nitrate, 0.114 g of LiDFOB, 10 g of 1M LiPF6 (EC / EMC, 3 / 7, v / v) and 0.02 g of azobisisobutyronitrile (AIBN) are uniformly mixed and stirred at room temperature to obtain a gel electrolyte precursor.

[0096] S2, the positive electrode tab includes a positive electrode material coating layer composed of a commercial high-nickel ternary positive electrode active material, PVDF and single-walled CNTs in a mass ratio of 9:0.5:0.5; the negative electrode tab includes a negative electrode material coating layer, and the negative electrode material is composed of a commercial silicon-carbon 550 negative electrode active material, sodium carboxymethyl cellulose (CMC), butadiene rubber latex (SBR) and single-walled CNTs in a mass ratio of 9:0.25:0.25:0.5. The positive electrode tab and the negative electrode tab are made into a dry cell in a laminated form, and after the dry cell is baked, 15g of the above precursor is injected into a 10Ah dry cell, and the dry cell is left to stand at room temperature for 10h.

[0097] S3, the cell is cured at 45°C for 6h, and then cured at 60°C for 2h to obtain an in-situ polymerized electrolyte lithium metal battery.

[0098] Comparative Example 2

[0099] Compared with Example 3, the comparative example lacks the terminal acrylate group polyglycidyl ether nitrate monomer, and the polymerized monomers are composed of 0.5g of polyethylene glycol diacrylate (Mn=600) and 1.5g of methyl methacrylate, and specifically include the following steps:

[0100] S1, under the condition that the water and oxygen concentration is less than 0.1ppm, 0.5g of polyethylene glycol diacrylate (Mn=600), 1.5g of methyl methacrylate, 0.114g of LiDFOB, 10g of 1M LiPF6 (EC / EMC, 3 / 7, v / v) and 0.02g of azobisisobutyronitrile (AIBN) are uniformly mixed, and stirred at room temperature to obtain a gel electrolyte precursor.

[0101] S2, the positive electrode tab includes a positive electrode material coating layer composed of a commercial high-nickel ternary positive electrode active material, PVDF and single-walled CNTs in a mass ratio of 9:0.5:0.5; the negative electrode tab includes a negative electrode material coating layer, and the negative electrode material is composed of a commercial silicon-carbon 550 negative electrode active material, sodium carboxymethyl cellulose (CMC), butadiene rubber latex (SBR) and single-walled CNTs in a mass ratio of 9:0.25:0.25:0.5. The positive electrode tab and the negative electrode tab are made into a dry cell in a laminated form, and after the dry cell is baked, 15g of the above precursor is injected into a 10Ah dry cell, and the dry cell is left to stand at room temperature for 10h.

[0102] S3, the cell is cured at 45°C for 6h, and then cured at 60°C for 2h to obtain an in-situ polymerized electrolyte lithium metal battery.

[0103] Comparative Example 3

[0104] The comparative example is compared with Example 4. The comparative example lacks the end-acrylate-based polyglycidyl ether nitrate monomer, and the polymerized monomers consist of 0.5 g of polyethylene glycol diacrylate (Mn = 600) and 1.5 g of styrene, and specifically includes the following steps:

[0105] S1, under the condition that the concentration of water and oxygen is less than 0.1 ppm, 0.5 g of polyethylene glycol diacrylate (Mn = 600), 1.5 g of styrene, 0.114 g of LiDFOB, 10 g of 1M LiPF6 (EC / EMC, 3 / 7, v / v) and 0.02 g of azobisisobutyronitrile (AIBN) are uniformly mixed, and stirred at room temperature to obtain a gel electrolyte precursor.

[0106] S2, the positive electrode tab includes a positive electrode material coating layer composed of a commercial high-nickel ternary positive electrode active material, PVDF and single-walled CNT at a mass ratio of 9:0.5:0.5; the negative electrode tab includes a negative electrode material coating layer composed of a commercial silicon-carbon 550 negative electrode active material, sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber latex (SBR) and single-walled CNT at a mass ratio of 9:0.25:0.25:0.5. The positive electrode tab and the negative electrode tab are made into a dry cell in the form of a laminated sheet. After baking the dry cell, 15 g of the above-mentioned precursor is injected into a 10 Ah dry cell, and the dry cell is left to stand at room temperature for 10 h.

[0107] S3, the cell is cured at 45°C for 6 h, and then cured at 60°C for 2 h to obtain an in-situ polymerized electrolyte lithium metal battery.

[0108] Comparative Example 4

[0109] The comparative example is compared with Example 5. The comparative example lacks the end-acrylate-based polyglycidyl ether nitrate monomer, and the polymerized monomers consist of 0.5 g of polyethylene glycol diacrylate (Mn = 600) and 1.5 g of trifluoroethyl methacrylate, and specifically includes the following steps:

[0110] S1, under the condition that the concentration of water and oxygen is less than 0.1 ppm, 0.5 g of polyethylene glycol diacrylate (Mn = 600), 1.5 g of trifluoroethyl methacrylate, 0.114 g of LiDFOB, 10 g of 1M LiPF6 (EC / EMC, 3 / 7, v / v) and 0.02 g of azobisisobutyronitrile (AIBN) are uniformly mixed, and stirred at room temperature to obtain a gel electrolyte precursor.

[0111] S2, the positive electrode tab includes a positive electrode material coating layer composed of a commercial high-nickel ternary positive electrode active material, PVDF and single-walled CNTs at a mass ratio of 9:0.5:0.5; the negative electrode tab includes a negative electrode material coating layer, and the negative electrode material is composed of a commercial silicon-carbon 550 negative electrode active material, sodium carboxymethyl cellulose (CMC), butadiene rubber latex (SBR) and single-walled CNTs at a mass ratio of 9:0.25:0.25:0.5. The positive electrode tab and the negative electrode tab are made into a dry cell in a laminated form, and after the dry cell is baked, 15g of the above precursor is injected into a 10Ah dry cell, and the dry cell is left to stand at room temperature for 10h.

[0112] S3, the cell is cured at 45°C for 6h, and then cured at 60°C for 2h to obtain an in-situ polymerized electrolyte lithium metal battery.

[0113] Comparative Example 5

[0114] This comparative example is compared with Example 6, and the comparative example lacks an end-acrylate group polyglycidyl ether nitrate monomer, and the polymerized monomer is 1g of polyethylene glycol diacrylate (Mn=600), and specifically includes the following steps:

[0115] S1, under the condition that the water and oxygen concentration is less than 0.1ppm, 1g of end-polyethylene glycol diacrylate, 0.114g of LiDFOB, 10g of 1M LiPF6 (EC / EMC, 3 / 7, v / v) and 0.02g of azobisisobutyronitrile (AIBN) are uniformly mixed, and stirred at room temperature to obtain a gel electrolyte precursor.

[0116] S2, the positive electrode tab includes a positive electrode material coating layer composed of a commercial high-nickel ternary positive electrode active material, PVDF and single-walled CNTs at a mass ratio of 9:0.5:0.5; the negative electrode tab includes a negative electrode material coating layer, and the negative electrode material is composed of a commercial silicon-carbon 550 negative electrode active material, sodium carboxymethyl cellulose (CMC), butadiene rubber latex (SBR) and single-walled CNTs at a mass ratio of 9:0.25:0.25:0.5. The positive electrode tab and the negative electrode tab are made into a dry cell in a laminated form, and after the dry cell is baked, 15g of the above precursor is injected into a 10Ah dry cell, and the dry cell is left to stand at room temperature for 10h.

[0117] S3, the cell is cured at 45°C for 6h, and then cured at 60°C for 2h to obtain an in-situ polymerized electrolyte lithium metal battery.

[0118] Performance test:

[0119] (1) Electrochemical window (V): the linear sweep voltammetry (LSV) curves of the in-situ polymerized electrolyte lithium metal batteries of each example and comparative example are tested by using an electrochemical workstation, and the electrochemical window is determined therefrom, the test voltage range is 3~6V, and the scanning rate is 1mV / s.

[0120] (2) The first cycle coulombic efficiency (%) and the capacity retention rate (%) after 50 cycles: the above in-situ polymerized electrolyte lithium battery was subjected to cycle performance test, at 25℃, in the range of 2.5~4.2V, with a current of 0.33C for charge and discharge cycle for 50 cycles, the first cycle coulombic efficiency of the battery and the capacity retention rate of the battery after 50 cycles were recorded.

[0121] The test results are shown in Table 1.

[0122] Table 1

[0123]

[0124] From the above examples, the electrochemical window of the lithium battery of the present application reaches 4.3-4.6V, the first cycle coulombic efficiency reaches 83-89%, and the capacity retention rate after 50 cycles is 76-86%.

[0125] From Examples 1-10 and Comparative Examples 1-5, in the preparation method of the present application, the end-acrylate group polyglycidyl ether nitrate is used as a polymerization monomer, and is in-situ polymerized with another type of vinyl monomer to form a polymer in the gel electrolyte, so that there is a nitro group in the polymer skeleton in the gel electrolyte, which is conducive to the formation of stable CEI and SEI at the interface of the positive electrode and the negative electrode, respectively, and is conducive to improving the electrochemical stability and lithium ion transmission performance at the interface, thereby achieving the purpose of improving the electrochemical window, cycle stability and coulombic efficiency of the battery. At the same time, from Example 11, when the end-acrylate group polyglycidyl ether nitrate is subjected to self-polymerization as the polymer skeleton of the gel electrolyte, the battery still has good cycle stability and coulombic efficiency.

[0126] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A gel electrolyte characterized by, a polymer obtained by polymerization of the monomer A itself, or a polymer obtained by polymerization of the monomer A and the monomer B; the monomer A comprises a compound represented by a general chemical structure (I): ， n is an integer from 1 to 100; the monomer B comprises at least one of an acrylate monomer, a nitrile group-containing vinyl monomer, an amide group-containing vinyl monomer, a sulfone group-containing vinyl monomer, a styrene monomer, or an ester group-containing vinyl monomer; further comprising a solvent and a lithium salt.

2. The gel electrolyte of claim 1, wherein the monomer B comprises at least one of polyethylene glycol diacrylate, polyethylene glycol acrylate, polyethylene glycol dimethacrylate, poly(ethylene glycol) methyl methacrylate, methyl acrylate, acryloyl isocyanate, methacrylate, trifluoroethyl methacrylate, hexafluorobutyl methacrylate, dimethyl allyl dicarboxylate, diethyl allyl malonate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, ethoxylated trimethylolpropane triacrylate, acrylonitrile, acrylamide, N,N-methylenebis(acrylamide), methyl vinyl sulfone, ethyl vinyl sulfone, vinyl acetate, styrene, 4-fluorostyrene, 3-fluorostyrene, 3,4-difluorostyrene, pentafluorostyrene, vinylene carbonate, or vinyl ethylene carbonate.

3. The gel electrolyte of claim 1, wherein The mass percentage of the monomer A is 0.1% to 30%, and the mass percentage of the monomer B is 0% to 50%, based on the mass of the gel electrolyte.

4. The gel electrolyte of claim 1, wherein The polymerization is independently selected to be performed in the presence of an initiator, the initiator comprising at least one of azobisisobutyronitrile, cyclohexanone peroxide, azobisisoheptane nitrile, tert-butyl hydroperoxide, or dimethyl azobisisobutyrate; the mass percentage of the initiator is 0.01% to 5%, based on the mass of the gel electrolyte.

5. The gel electrolyte of claim 1, wherein The mass percentage of the lithium salt is 5% to 60%, and the mass percentage of the solvent is 0.1% to 95%, based on the mass of the gel electrolyte.

6. The gel electrolyte of claim 5, wherein comprises at least one of the following I or II: I. the lithium salt comprises at least one of lithium hexafluorophosphate, lithium bis(trifluoromethylsulfonyl)imide, lithium bisfluorosulfonylimide, lithium tetrafluoroborate, lithium difluoro(oxalato)borate, lithium difluoro(dioxalato)phosphate, lithium dioxalato borate, lithium trifluoromethylsulfonate, lithium tetrafluoroaluminate, lithium 4,5-dicyano-2-trifluoromethylimidazole, lithium hexafluoroarsenate, lithium perchlorate, lithium difluorophosphate, or lithium nitrate; II. The solvent includes at least one of ethylene carbonate, fluoroethylene carbonate, vinyl ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl trifluoroethyl carbonate, butylene carbonate, methyl propyl carbonate, methyl formate, ethyl formate, propyl formate, butyl formate, ethyl acetate, ethyl difluoroacetate, ethyl trifluoroacetate, propyl acetate, butyl acetate, methyl propionate, methyl trifluoro propionate, ethyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, δ-valerolactone, 2-methyl tetrahydrofuran, 4-methyl-1,3-dioxolane, 2-methyl-1,3-dioxolane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, butyrolactone, hexanenitrile, fluorinated acetonitrile, ethylene sulfate, hexaphenoxy cyclotriphosphazene, hexafluorotriphosphazene, ethoxy pentafluorocyclotriphosphazene, tricresyl phosphate, trimethyl phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate, or cresyl diphenyl phosphate.

7. The gel electrolyte of claim 1, wherein Further comprising inorganic particles; the inorganic particles include at least one of titanium dioxide, di-aluminum oxide, zirconium oxide, nickel oxide, silicon nitride, silicon dioxide and / or aerogel powder thereof, sulfide solid electrolyte material, garnet-type solid electrolyte material, perovskite-type solid electrolyte material, NASICON-type solid electrolyte material, halide solid electrolyte material; The mass percentage content of the inorganic particles is 0.01%-9% based on the mass of the gel electrolyte.

8. A secondary battery characterized by comprising: The secondary battery comprises a positive electrode sheet, a negative electrode sheet, a separator, and the gel electrolyte according to any one of claims 1-7.

9. A method of producing the secondary battery according to claim 8, characterized by, The method comprises the following steps: S1, mixing monomer A or monomer A and monomer B, and other raw materials to obtain a gel electrolyte precursor; S2, laminating the positive electrode sheet, the separator, and the negative electrode sheet to obtain a dry cell; S3, injecting the gel electrolyte precursor into the dry cell, and sequentially standing and polymerizing to obtain the secondary battery.

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