Composite material and method for manufacturing same, composite gel electrolyte and method for manufacturing same and use thereof

Abstract

The present application relates to the technical field of lithium battery, and especially relates to a composite material and a preparation method thereof, a composite gel electrolyte and a preparation method and application thereof. The composite material comprises inorganic nanoparticles and a polymer coated on the surface of the inorganic nanoparticles by in-situ polymerization; the inorganic nanoparticles comprise POSS and derivatives thereof and / or halloysite; the polymer monomer comprises a first polymer monomer, a second polymer monomer and a third polymer monomer; the first polymer monomer comprises an unsaturated olefin compound containing an epoxy group; the second polymer monomer comprises acrylonitrile or a derivative of acrylonitrile; and the third polymer monomer comprises a multi-armed polyethylene glycol maleimide and / or a multi-armed polyethylene glycol acrylate. The inorganic nanoparticles of the present application can increase the non-combustible components in the system and improve the intrinsic safety of the material; the polymer can ensure the conduction of lithium ions; and the polymer is coated on the surface of the inorganic nanoparticles by in-situ polymerization, so that the interface pain point problem in the solid-state battery is solved.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, and in particular to a composite material and its preparation method, a composite gel electrolyte and its preparation method and application. Background Technology

[0002] Lithium-ion batteries are widely used in 3C (computers, communications, and consumer electronics) applications, power batteries, and energy storage due to their advantages such as high energy density, high output power, and long cycle life. However, traditional lithium-ion batteries use a liquid electrolyte system, which still poses risks of leakage, fire, combustion, and explosion during long-term use. Furthermore, high-energy-density lithium-ion batteries typically use a 622 or 822 ternary system, with Mn... 2+ The dissolution of transition metals is inevitable throughout the battery system. The continuous dissolution, diffusion, and deposition of transition metals cause ongoing damage to the SEI film on the negative electrode side of the battery, resulting in a decrease in the battery's cycle stability.

[0003] To address the safety concerns of lithium-ion batteries, researchers typically add flame-retardant components such as triethyl phosphate, fluoroethylene carbonate, and trifluoropropylene carbonate to existing electrolyte systems. However, the electrolyte itself remains liquid. Using electrolytes with these added components still presents the possibility of leakage, corrosion of components, and battery failure.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] One object of the present invention is to provide a composite material to solve technical problems such as leakage that may occur with liquid electrolytes in the prior art.

[0006] To achieve the above-mentioned objectives of this invention, the following technical solution is adopted:

[0007] Composite materials include inorganic nanoparticles and polymers coated on the surface of the inorganic nanoparticles by in-situ polymerization;

[0008] The inorganic nanoparticles include at least one of POSS and its derivatives and halloysite;

[0009] The polymer monomers include a first monomer, a second monomer, and a third monomer;

[0010] The first polymerization monomer includes an epoxy-containing unsaturated olefin compound;

[0011] The second polymerizing monomer includes acrylonitrile or a derivative of acrylonitrile;

[0012] The third polymeric monomer includes multi-arm polyethylene glycol maleimide and / or multi-arm polyethylene glycol acrylate.

[0013] The composite material of this invention involves in-situ polymerization of inorganic nanoparticles to coat them with a corresponding polymer. The inorganic nanoparticles increase the non-flammable components in the system, enhancing the intrinsic safety of the material; the polymer ensures lithium-ion conductivity. Furthermore, by coating the inorganic nanoparticles with the polymer through in-situ polymerization, the interfacial challenges in solid-state batteries are addressed.

[0014] In a specific embodiment of the present invention, the molar ratio of the first polymeric monomer to the second polymeric monomer in the polymer is (0.7-2):1; and the mass ratio of the first polymeric monomer to the third polymeric monomer is (2.5-400):1.

[0015] In a specific embodiment of the present invention, the mass of the inorganic nanoparticles is 0.01% to 20.0% of the total mass of the polymeric monomers.

[0016] Another object of the present invention is to provide a method for preparing composite materials, comprising the following steps:

[0017] The first, second, and third monomers are polymerized in situ with inorganic nanoparticles in a solvent under the action of an initiator.

[0018] The material after the in-situ polymerization reaction is dried.

[0019] In a specific embodiment of the present invention, the drying process includes any one or more of freeze drying, forced air drying, and vacuum drying.

[0020] In a specific embodiment of the present invention, the temperature of the in-situ polymerization reaction is 30–70°C; and the time of the in-situ polymerization reaction is 20–40 h.

[0021] In a specific embodiment of the present invention, the in-situ polymerization reaction is carried out using a gradient heating method. Further, the gradient heating includes: holding at 30–33°C for 1–2 hours, holding at 40–43°C for 1–2 hours, holding at 50–53°C for 1–2 hours, and holding at 55–70°C for 17–24 hours.

[0022] Another object of the present invention is to provide a composite gel electrolyte, comprising an electrolyte and any of the composite materials described above.

[0023] The composite gel electrolyte of this invention exhibits a certain degree of self-support after gelation treatment, which can "anchor" the liquid components within the bulk, thereby greatly reducing the risk of leakage and improving safety performance. Furthermore, the composite gel electrolyte of this invention has a high limiting oxygen index.

[0024] In a specific embodiment of the present invention, the mass fraction of the composite material in the composite gel electrolyte is 0.8% to 5.0%.

[0025] The present invention also provides a method for preparing any one of the above-described composite gel electrolytes, comprising the following steps:

[0026] The composite material is dissolved in the electrolyte and then gelled.

[0027] In a specific embodiment of the present invention, the gelation treatment includes: heating treatment at 45 to 50°C.

[0028] The present invention also provides a lithium-ion battery comprising any of the composite gel electrolytes described above.

[0029] The lithium-ion battery of the present invention has excellent cycle performance.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] (1) In the composite material of the present invention, inorganic nanoparticles can increase the non-combustible components in the system and improve the intrinsic safety of the material; polymers can ensure the conduction of lithium ions; and the in-situ polymer coating and inorganic nanoparticles solve the interface pain point problem in solid-state batteries.

[0032] (2) The composite gel electrolyte of the present invention can "anchor" the liquid components in the main body, thereby greatly reducing the risk of leakage and improving safety performance; at the same time, the composite gel electrolyte of the present invention has a high limiting oxygen index, and has a high lithium-ion conductivity and a stable electrochemical window.

[0033] (3) The composite gel electrolyte of the present invention can be directly used in existing lithium-ion batteries, and has the advantages of high efficiency, safety and convenience; the lithium-ion battery obtained has excellent cycle performance. Attached Figure Description

[0034] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0035] Figure 1 These are schematic diagrams of the composite material structure provided in some embodiments of the present invention;

[0036] Figure 2 An optical photograph of the composite gel electrolyte provided in Embodiment 1 of the present invention. Detailed Implementation

[0037] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0038] Composite materials include inorganic nanoparticles and polymers coated on the surface of the inorganic nanoparticles by in-situ polymerization;

[0039] The inorganic nanoparticles include at least one of POSS and its derivatives and halloysite;

[0040] The polymer monomers include a first monomer, a second monomer, and a third monomer;

[0041] The first polymerization monomer includes an epoxy-containing unsaturated olefin compound;

[0042] The second polymerizing monomer includes acrylonitrile or a derivative of acrylonitrile;

[0043] The third polymeric monomer includes multi-arm polyethylene glycol maleimide and / or multi-arm polyethylene glycol acrylate.

[0044] The composite material of this invention involves in-situ polymerization of inorganic nanoparticles to coat them with a corresponding polymer. The inorganic nanoparticles increase the non-flammable components in the system, enhancing the intrinsic safety of the material; the polymer ensures lithium-ion conductivity. Furthermore, by coating the inorganic nanoparticles with the polymer through in-situ polymerization, the interfacial challenges in solid-state batteries are addressed.

[0045] A schematic diagram of the composite material of the present invention is shown below. Figure 1As shown, in the composite material, the organic segments of the polymer polymerize in situ to coat the surface of the inorganic nanoparticles, forming inorganic particles M. Simultaneously, with the inorganic particles M as the core, they polymerize and grow in situ, forming a three-dimensional polymer network structure composed of organic segments between adjacent inorganic particles M. Furthermore, the composite material of this invention mainly consists of polymers and polymer-coated inorganic particles M; for illustrative purposes, some inorganic nanoparticles, such as inorganic particles B, that are not coated with polymers may exist, and their content is not limited.

[0046] In specific embodiments of the present invention, the POSS and its derivatives include POSS (cage-type polysilsesquioxane), hydroxy POSS, and amino POSS, etc.

[0047] In a specific embodiment of the present invention, the first polymeric monomer includes any one or more of glycidyl acrylate, glycidyl methacrylate, 4-hydroxybutyl acrylate glycidyl ether, and 2,3-glycidyl acrylate octadecenoic acid.

[0048] In a specific embodiment of the present invention, the second polymerizing monomer includes any one or more of 3-cyclopentylacrylonitrile, 3-phenylacrylonitrile, acrylonitrile, 3-(benzenesulfonyl)acrylonitrile, and 3-ethoxyacrylonitrile.

[0049] In a specific embodiment of the present invention, the third polymeric monomer comprises four-arm polyethylene glycol maleimide and / or four-arm polyethylene glycol acrylate.

[0050] In a specific embodiment of the present invention, the weight-average molecular weight of the four-arm polyethylene glycol maleimide is 2000-20000 Da, such as 5000 Da; the weight-average molecular weight of the four-arm polyethylene glycol acrylate is 1000-20000 Da, such as 2000 Da.

[0051] In different embodiments, the weight-average molecular weight of the four-arm polyethylene glycol maleimide can be, for example, 2000 Da, 4000 Da, 5000 Da, 8000 Da, 10000 Da, 12000 Da, 15000 Da, 18000 Da, 20000 Da, etc.; the weight-average molecular weight of the four-arm polyethylene glycol acrylate can be, for example, 1000 Da, 2000 Da, 5000 Da, 8000 Da, 10000 Da, 12000 Da, 15000 Da, 18000 Da, 20000 Da, etc.

[0052] In a specific embodiment of the present invention, the molar ratio of the first polymeric monomer to the second polymeric monomer in the polymer is (0.7-2):1, such as (1.3-1.4):1; the mass ratio of the first polymeric monomer to the third polymeric monomer is (2.5-400):1, such as (35-45):1.

[0053] In different embodiments, the molar ratio of the first polymeric monomer to the second polymeric monomer in the polymer may be, for example, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, etc.; and the mass ratio of the first polymeric monomer to the third polymeric monomer may be, for example, 2.5:1, 5.0:1, 10.0:1, 15.0:1, 20:1, 40:1, 60:1, 100:1, 200:1, 400:1, etc.

[0054] In a specific embodiment of the present invention, the mass of the inorganic nanoparticles is 0.01% to 20.0% of the total mass of the polymeric monomers, such as 0.5% to 5.5%.

[0055] In different embodiments, the mass of the inorganic nanoparticles may, for example, be 0.01%, 0.1%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, etc., of the total mass of the polymer monomers.

[0056] By employing an appropriate amount of inorganic nanoparticles, the limiting oxygen index, safety performance, and cycle performance of the composite gel electrolyte obtained from the composite material can be further guaranteed.

[0057] Another object of the present invention is to provide a method for preparing composite materials, comprising the following steps:

[0058] The first, second, and third monomers are polymerized in situ with inorganic nanoparticles in a solvent under the action of an initiator.

[0059] The material after the in-situ polymerization reaction is dried.

[0060] In a specific embodiment of the present invention, the drying process includes any one or more of freeze drying, forced air drying, and vacuum drying.

[0061] In a specific embodiment of the present invention, the freeze-drying includes: pre-freezing the material and then performing vacuum freeze-drying. The pre-freezing time can be 3-5 hours, such as 4 hours; the vacuum freeze-drying time can be 16-20 hours, such as 18 hours.

[0062] In a specific embodiment of the present invention, the temperature of the blower drying is 60-90°C, and the time of the blower drying is 4-10 hours.

[0063] In a specific embodiment of the present invention, the vacuum drying temperature is 60-90°C, and the vacuum drying time is 4-48 hours.

[0064] The specific times for freeze drying, forced air drying, and vacuum drying can be adjusted according to the actual drying conditions. The above drying methods are used to remove solvents and incompletely reacted monomers from the material, thereby improving the purity of the composite material.

[0065] In a specific embodiment of the present invention, the solvent includes a non-aqueous organic solvent. Further, the solvent includes any one or more of dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, propylene carbonate, ethylene carbonate, fluoroethylene carbonate, tetraethylene glycol dimethyl ether, ethylene glycol dimethyl ether, 1,3-dioxane, ethyl acetate, γ-butyrolactone, 6-caprolactone, acetonitrile, and sulfolane.

[0066] The solvents mentioned above are commonly used in lithium-ion battery electrolytes. On the one hand, these solvents can ensure that each component undergoes in-situ polymerization reaction in the corresponding solution system; on the other hand, even if there are trace amounts of solvent residue after drying, the stable operation of the battery can be guaranteed without introducing other impurities.

[0067] In a specific embodiment of the present invention, the solvent comprises dimethyl carbonate and ethyl methyl carbonate. Further, the volume ratio of dimethyl carbonate to ethyl methyl carbonate in the solvent is 1:1.

[0068] In a specific embodiment of the present invention, the ratio of the amount of solvent used to the total mass of the first polymeric monomer, the second polymeric monomer, and the third polymeric monomer is (2.9904–5.607) mL: 1 g. This means that the amount of solvent used is (2.990–5.607) mL relative to 1 g of the mixture of the three polymeric monomers, and is not a limitation on the specific amounts of polymeric monomers and solvent used.

[0069] In different embodiments, the ratio of the amount of solvent to the mass of each monomer can be exemplarily 3 mL: 1 g, 3.5 mL: 1 g, 4 mL: 1 g, 4.5 mL: 1 g, 5 mL: 1 g, 5.5 mL: 1 g, etc.

[0070] In a specific embodiment of the present invention, the initiator includes a free radical polymer initiator. Further, the initiator includes at least one of an azo initiator and a peroxide initiator. For example, the azo initiator includes any one or more of azobisisobutyronitrile and azobisisoheptanenitrile; the peroxide initiator includes any one or more of benzoyl peroxide, tert-butyl peroxide, and methyl ethyl ketone peroxide.

[0071] In practice, the amount of the initiator used is 0.5% to 1.5% of the total mass of the polymerizing monomers, such as 1%.

[0072] In a specific embodiment of the present invention, the temperature of the in-situ polymerization reaction is 30–70°C; the time of the in-situ polymerization reaction is 20–40 h. Furthermore, during the in-situ polymerization reaction, stirring is performed to ensure that the inorganic nanoparticles are effectively coated and dispersed throughout the overall composite material system.

[0073] In different embodiments, the temperature of the in-situ polymerization reaction can be, for example, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 58°C, 60°C, 62°C, 65°C, 68°C, 70°C, etc.; and the time of the in-situ polymerization reaction can be, for example, 20h, 22h, 24h, 28h, 32h, 36h, 40h, etc.

[0074] In a specific embodiment of the present invention, the in-situ polymerization reaction is carried out using a gradient heating method. Further, the gradient heating includes: holding at 30–33°C for 1–2 hours, holding at 40–43°C for 1–2 hours, holding at 50–53°C for 1–2 hours, and holding at 55–70°C for 17–24 hours.

[0075] In practice, the precursor liquid can be pre-transferred into a sealed reactor and heated using the gradient heating method described above; alternatively, the precursor liquid can be pre-transferred into a sealed reactor for inert gas exchange, and heated at a constant temperature (55–70°C) in an inert gas atmosphere. The inert gas can be high-purity argon.

[0076] In some specific embodiments of the present invention, the method for preparing the composite material may include the following steps:

[0077] (a) The first polymerizing monomer, the second polymerizing monomer and the third polymerizing monomer are pre-dissolved in a solvent, then an initiator is added, and after the dispersion is uniform, inorganic nanoparticles are added and dispersed uniformly to obtain a precursor solution.

[0078] (b) The precursor liquid is heated to induce an in-situ polymerization reaction by the initiator; then the material after the in-situ polymerization reaction is dried.

[0079] In a specific embodiment of the present invention, during the preparation, the amount of the inorganic nanoparticles is 0.01% to 20.0% of the total mass of the first polymeric monomer, the second polymeric monomer, and the third polymeric monomer, preferably 0.5% to 5.5%, such as 2%.

[0080] In a specific embodiment of the present invention, before drying the material after the in-situ polymerization reaction, the method further includes: purifying the material after the in-situ polymerization reaction; the purification includes: mixing the material after the in-situ polymerization reaction with an aqueous ethanol solution, precipitating a solid, and collecting the solid.

[0081] In a specific embodiment of the present invention, the volume ratio of ethanol to water in the ethanol-water solution is (2.5 to 3.5):1, such as 3:1.

[0082] Another object of the present invention is to provide a composite gel electrolyte, comprising an electrolyte and any of the composite materials described above.

[0083] The composite gel electrolyte of this invention exhibits a certain degree of self-support after gelation treatment, which can "anchor" the liquid components within the bulk, thereby greatly reducing the risk of leakage and improving safety performance. Furthermore, the composite gel electrolyte of this invention has a high limiting oxygen index.

[0084] In a specific embodiment of the present invention, the mass fraction of the composite material in the composite gel electrolyte is 0.8% to 5.0%.

[0085] In different embodiments, the mass fraction of the composite material in the composite gel electrolyte can be, for example, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc.

[0086] The electrolyte used in the composite gel electrolyte of the present invention can be a conventional electrolyte. The composite material can be directly compounded with the existing electrolyte in a certain proportion and then gelled, without changing the existing battery manufacturing process.

[0087] Specifically, the electrolyte may include a non-aqueous organic solvent, a lithium salt, and additives. The non-aqueous organic solvent may include one or more of dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, propylene carbonate, ethylene carbonate, fluoroethylene carbonate, tetraethylene glycol dimethyl ether, ethylene glycol dimethyl ether, 1,3-dioxane, ethyl acetate, γ-butyrolactone, 6-caprolactone, acetonitrile, and sulfolane. The lithium salt may include at least one of LiPF6, LiBF4, LiBOB, LiDFOB, LiDFOP, LiFSI, and LiTFSI. The additives may be one or more of fluoroethylene carbonate, ethylene ethylene carbonate, and lithium difluorophosphate. The amounts of each component can be adjusted according to conventional dosages.

[0088] When the composite material of the present invention is used in composite gel electrolytes, it can be directly used in existing lithium-ion electrolytes, and has the characteristics of high efficiency and convenience.

[0089] The present invention also provides a method for preparing any one of the above-described composite gel electrolytes, comprising the following steps:

[0090] The composite material is dissolved in the electrolyte and then gelled.

[0091] In a specific embodiment of the present invention, the gelation treatment includes: heating treatment at 45 to 50°C.

[0092] In different embodiments, the temperature of the heat treatment can be, for example, 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, etc.

[0093] In a specific embodiment of the present invention, the heating treatment time is 10 to 30 hours.

[0094] In practice, the processes of dissolving the composite material in the electrolyte and gelling can be carried out continuously or separately. For example, the composite material can be dissolved in the electrolyte in advance according to a certain ratio, and then injected with electrolyte after assembling the battery, sealed, and then gelled.

[0095] The present invention also provides a lithium-ion battery comprising any of the composite gel electrolytes described above.

[0096] In the preparation of the above-mentioned lithium-ion battery, the existing battery preparation process can be used. The difference is that when preparing the electrolyte, a composite material is added to the existing electrolyte in a certain proportion to obtain a mixture. Then, the mixture is injected into the electrolyte, the battery is sealed, and then the mixture is allowed to stand at 45-50°C to complete the gelation and obtain the corresponding lithium-ion battery.

[0097] Example 1

[0098] This embodiment provides a method for preparing a composite gel electrolyte, including the following steps:

[0099] (1) Weigh dimethyl carbonate and ethyl methyl carbonate in a glove box at a volume ratio of 1:1. Based on the molar ratio of glycidyl acrylate to 3-cyclopentylacrylonitrile of 1.37:1 and the mass ratio of glycidyl acrylate to 4arm-PEG Maleimide (Mw = 5000 Da) of 40:1, weigh and mix the reaction monomers thoroughly. The total mass of monomers and the volume ratio of solvent are 1 g: 3.73 mL. Then add the initiator azobisisobutyronitrile (1 wt% of the total mass of each monomer). After the initiator is evenly dispersed, add POSS (cage-type polysilsesquioxane) to obtain the precursor solution. The amount of POSS is 2 wt% of the total mass of monomers.

[0100] (2) Heat the precursor liquid obtained in step (1) to 55°C and stir for 24 hours. Then pre-freeze the reacted material for 4 hours and freeze-dry it in a freeze dryer for 18 hours to obtain the composite material PreCGPN.

[0101] (3) Dissolve the PreCGPN composite material obtained in step (2) in the electrolyte, stir and disperse to obtain a mixture; wherein, the mass fraction of the PreCGPN composite material in the mixture is 2wt%. Then heat the mixture at 45℃ for 20h to obtain the composite gel electrolyte CGPN.

[0102] The electrolyte can be a commercially available electrolyte, such as an electrolyte containing a solvent, a lithium salt, and an additive; the solvent is ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate in a volume ratio of 1:1:1; the lithium salt is LiPF6 with a concentration of approximately 1.1 mol / L; and the additive is fluoroethylene carbonate with a mass fraction of 2 wt% in the electrolyte.

[0103] like Figure 2 As shown, it is an optical photograph of the composite gel electrolyte prepared in Example 1 of the present invention. As can be seen from the figure, the composite gel electrolyte obtained by gelation treatment in the present invention has certain self-supporting properties.

[0104] Example 2

[0105] This embodiment provides a method for preparing a composite gel electrolyte, referring to Embodiment 1, except that the types of inorganic nano-ions are different. In this embodiment, POSS in step (1) is replaced with an equal mass of halloysite.

[0106] Example 3

[0107] This embodiment provides a method for preparing a composite gel electrolyte, referring to Example 1, except that the monomer ratio is different in step (1). In this embodiment, the relevant ratios of glycidyl acrylate, 3-cyclopentylacrylonitrile, and 4arm-PEG Maleimide (four-arm PEG maleimide, Mw = 5000 Da) are as follows: the molar ratio of glycidyl acrylate to 3-cyclopentylacrylonitrile is 1:1, and the mass ratio of glycidyl acrylate to 4arm-PEG Maleimide is 30:1.

[0108] Example 4

[0109] This embodiment provides a method for preparing a composite gel electrolyte, referring to Example 1, with the only difference being the monomer ratio in step (1). In this embodiment, the relevant ratios of glycidyl acrylate, 3-cyclopentylacrylonitrile, and 4arm-PEG Maleimide (four-arm PEG maleimide, Mw = 5000 Da) are as follows: the molar ratio of glycidyl acrylate to 3-cyclopentylacrylonitrile is 1:1.37, and the mass ratio of glycidyl acrylate to 4arm-PEG Maleimide is 20:1.

[0110] Example 5

[0111] This embodiment provides a method for preparing a composite gel electrolyte. Referring to Example 1, the only difference is that the monomer type is different in step (1). In this embodiment, 4arm-PEG Maleimide (four-arm PEG maleimide, Mw = 5000 Da) in step (1) is replaced with an equal mass of 4arm-PEG Acrylate (four-arm PEG acrylate, Mw approximately 2000 Da).

[0112] Example 6

[0113] This embodiment provides a method for preparing a composite gel electrolyte, referring to Embodiment 1, except that the monomers are different in step (1). In this embodiment, glycidyl acrylate in step (1) is replaced with an equimolar amount of glycidyl methacrylate, and 3-cyclopentylacrylonitrile is replaced with an equimolar amount of 3-(benzenesulfonyl)acrylonitrile.

[0114] Example 7

[0115] This embodiment provides a method for preparing a composite gel electrolyte, referring to Embodiment 1, except that the amount of POSS used in step (1) is different. In this embodiment, the amount of POSS used is 0.2 wt% of the total mass of the monomers.

[0116] Example 8

[0117] This embodiment provides a method for preparing a composite gel electrolyte, referring to Embodiment 1, except that the amount of POSS used in step (1) is different. In this embodiment, the amount of POSS used is 20.0 wt% of the total mass of the monomers.

[0118] Example 9

[0119] This embodiment provides a method for preparing a composite gel electrolyte. Referring to Embodiment 1, the only difference is that step (2) includes a purification process before drying. Specifically, in this embodiment, the precursor solution obtained in step (1) is heated to 55°C and stirred for 24 hours. Then, the reacted material is mixed with an ethanol-water solution (ethanol / water volume ratio of 75 / 25), stirred to precipitate a solid, filtered, and the solid is collected. The solid is then pre-frozen for 4 hours and then freeze-dried in a freeze dryer for 18 hours to obtain the composite material PreCGPN.

[0120] Example 10

[0121] This embodiment provides a method for preparing a composite gel electrolyte, referring to Embodiment 1, except that the amount of composite material used in step (3) is different. In this embodiment, the mass fraction of the composite material PreCGPN in the mixture is 3 wt%.

[0122] Example 11

[0123] This embodiment provides a method for preparing a composite gel electrolyte, referring to Embodiment 1, except that the amount of composite material used in step (3) is different. In this embodiment, the mass fraction of the composite material PreCGPN in the mixture is 4 wt%.

[0124] Example 12

[0125] This embodiment provides a method for preparing a composite gel electrolyte, referring to Embodiment 1, with the only difference being the heating treatment method in step (2). In this embodiment, step (2) includes: stirring and heating the precursor liquid obtained in step (1) to 30°C for 1 hour, 40°C for 1 hour, 50°C for 1 hour, and 55°C for 21 hours, then pre-freezing the reacted material for 4 hours, and then freeze-drying it in a freeze dryer for 18 hours to obtain the composite material PreCGPN.

[0126] Example 13

[0127] This embodiment provides a method for preparing a composite gel electrolyte, referring to Embodiment 1, except that the amount of PreCGPN composite material added in step (3) is different. In this embodiment, the amount of PreCGPN composite material is 0.2 wt% of the total mass of the monomers.

[0128] Example 14

[0129] This embodiment provides a method for preparing a composite gel electrolyte, referring to Embodiment 1, except that the amount of PreCGPN composite material added in step (3) is different. In this embodiment, the amount of PreCGPN composite material is 10 wt% of the total mass of the monomers.

[0130] Example 15

[0131] This embodiment provides a method for preparing a composite gel electrolyte, referring to Embodiment 1, except that the amount of PreCGPN composite material added in step (3) is different. In this embodiment, the amount of PreCGPN composite material is 20 wt% of the total mass of the monomers.

[0132] Experimental Example 1

[0133] Table 1 shows the test results of room temperature lithium-ion conductivity and limiting oxygen index (LOI) of the composite gel electrolyte materials obtained in different embodiments. In the LOI test, the gas flow rate was controlled at 40 mm / s, oxygen was selected as the combustion-supporting gas, and nitrogen was selected as the inert gas.

[0134] Table 1. Room temperature lithium-ion conductivity and LOI of different composite gel electrolyte materials

[0135]

[0136] The test results above show that the composite gel electrolyte of the present invention has high lithium-ion conductivity and limiting oxygen index. In particular, under certain inorganic nanoparticle dosage conditions, it can ensure both high lithium-ion conductivity and high limiting oxygen index, thereby improving the safety performance of the material.

[0137] Experimental Example 2

[0138] According to the preparation method of the composite gel electrolyte in each embodiment, a mixture of composite materials dissolved in electrolyte is first obtained, the battery is assembled, the mixture is then injected with electrolyte, the battery is sealed, and after standing at room temperature for 12 hours, it is placed at 45°C for 12 hours to obtain the composite gel lithium-ion battery. Charge-discharge tests were conducted on each composite gel lithium-ion battery at operating voltages of 2.8-4.2V. The current density during the formation stage was 0.2C / 0.2C, and the charge-discharge current density during the cycle stage was 1.0C / 1.0C. The test results are shown in Table 2.

[0139] The battery uses ternary materials for the positive electrode (nickel-cobalt-manganese ratio of 6:2:2), graphite for the negative electrode, and a single-sided coated PE separator (ceramic side facing the positive electrode). The cell liquid injection coefficient is 2.1 g / Ah.

[0140] Table 2 Cycle performance test results of different composite gel lithium-ion batteries

[0141]

[0142]

[0143] The test results above show that the composite gel lithium-ion battery prepared by adding a certain amount of composite material to the electrolyte can improve the cycle performance of the battery cell.

[0144] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite gel electrolyte, characterized in that, Including composite materials and electrolytes; The composite material includes inorganic nanoparticles and an in-situ polymer coated on the surface of the inorganic nanoparticles; The inorganic nanoparticles include at least one of POSS and its derivatives and halloysite; The polymer monomers include a first monomer, a second monomer, and a third monomer; The first polymerization monomer includes an epoxy-containing unsaturated olefin compound; The second polymerizing monomer includes acrylonitrile or a derivative of acrylonitrile; The third polymeric monomer includes multi-arm polyethylene glycol maleimide and / or multi-arm polyethylene glycol acrylate; The molar ratio of the first polymeric monomer to the second polymeric monomer is (1.3~1.4):1; The mass ratio of the first polymeric monomer to the third polymeric monomer is (35~45):1; The mass of the inorganic nanoparticles is 0.5% to 4% of the sum of the masses of the first polymeric monomer, the second polymeric monomer, and the third polymeric monomer.

2. The composite gel electrolyte according to claim 1, characterized in that, The first polymeric monomer includes any one or more of glycidyl acrylate, glycidyl methacrylate, 4-hydroxybutyl acrylate glycidyl ether, and 2,3-glycidyl acrylate octadecenoic acid. The second polymerization monomer includes any one or more of 3-cyclopentylacrylonitrile, 3-phenylacrylonitrile, acrylonitrile, 3-(benzenesulfonyl)acrylonitrile, and 3-ethoxyacrylonitrile; The third polymeric monomer comprises four-armed polyethylene glycol maleimide and / or four-armed polyethylene glycol acrylate.

3. The composite gel electrolyte according to claim 1, characterized in that, The preparation method of the composite material includes the following steps: The first, second, and third monomers are polymerized in situ with inorganic nanoparticles in a solvent under the action of an initiator. The material after the in-situ polymerization reaction is dried.

4. The composite gel electrolyte according to claim 3, characterized in that, The in-situ polymerization reaction is carried out at a temperature of 30~70℃ and for a duration of 20~40h.

5. The composite gel electrolyte according to claim 3, characterized in that, In the in-situ polymerization reaction, a gradient heating method is used; The gradient temperature increase includes: holding at 30~33℃ for 1~2 hours, holding at 40~43℃ for 1~2 hours, holding at 50~53℃ for 1~2 hours, and holding at 55~70℃ for 17~24 hours.

6. The composite gel electrolyte according to claim 3, characterized in that, It has at least one of the following features (1) to (3): (1) The drying process includes any one or more of the following: freeze drying, forced air drying, and vacuum drying; (2) The solvent includes any one or more of dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl propyl carbonate, diphenyl carbonate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, γ-butyrolactone, acetonitrile and sulfolane. (3) The initiator includes at least one of azo initiators and peroxide initiators.

7. The composite gel electrolyte according to claim 1, characterized in that, In the composite gel electrolyte, the mass fraction of the composite material is 0.8% to 5.0%.

8. The method for preparing the composite gel electrolyte according to any one of claims 1 to 7, characterized in that, Includes the following steps: The composite material is dissolved in the electrolyte and then gelled.

9. The method for preparing the composite gel electrolyte according to claim 8, characterized in that, The gelation treatment includes heating at 45~50℃.

10. A lithium-ion battery, characterized in that, Includes the composite gel electrolyte according to any one of claims 1 to 7.

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