Electrolyte, gel electrolyte and lithium ion battery

Abstract

The invention provides an electrolyte, a gel electrolyte and a lithium ion battery. The electrolyte comprises a functional monomer, a lithium salt, an additive, an organic solvent and an initiator, wherein the additive comprises a metal salt additive; the electrolyte meets the following relational expression: A / (Z + C) is more than or equal to 0.0588 and less than or equal to 0.7143; the electrolyte provided by the invention is polymerized to obtain a gel electrolyte, so that gas production can be reduced and high-temperature storage performance can be improved in a high-temperature environment, meanwhile, metal ions in the metal salt additive and functional monomers are subjected to coordination cross-linking, in-situ gelation is initiated through the metal ions, a structure with a three-dimensional network is formed, and the performance of the electrolyte is improved. The three-dimensional network structure is tightly attached to the surface of the electrode to form a protective film, and the protective film can effectively isolate the contact between an electrolyte and an electrode active material, so that the side reaction between the electrolyte and an interface in the circulation process is reduced, the dissolution of transition metal on one side of a positive electrode is inhibited, and the purpose of improving the circulation performance is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion batteries, in particular to a gel electrolyte and a lithium ion battery. BACKGROUND

[0002] In lithium ion batteries and high-voltage positive electrode system energy storage devices, local high-salt electrolyte (LHCE) is concerned due to its unique solvation structure design. By introducing high-concentration lithium salt and low-solvent diluent, a local high-salt environment rich in anions is formed at the electrode interface, which can inhibit lithium dendrite growth and improve high-voltage compatibility (>4.5 V). In addition, it can also reduce the side reactions between the solvent and the interface. However, in the specific application of high-voltage positive electrode system energy storage, the high salt content leads to the increase of raw material cost, and the excess lithium salt is easy to cause side reactions in the cycle process, which reduces the interface stability. The compatibility of diluent and main solvent may cause phase separation, especially in the wide temperature range working conditions, which aggravates the performance decay. Moreover, the existing system has limited regulation on the electrode / electrolyte interface dynamics, and it is difficult to balance high ionic conductivity and low interface impedance. The above defects seriously restrict the storage and cycle performance of lithium ion batteries. SUMMARY

[0003] In view of the poor storage and cycle performance of lithium ion batteries with high-salt electrolyte in the prior art, a gel electrolyte and a lithium ion battery are provided.

[0004] The technical solution adopted by the present application to solve the above technical problems is as follows: On the one hand, the present application provides an electrolyte, which comprises a functional monomer, a lithium salt, an additive, an organic solvent and an initiator, wherein the additive comprises a metal salt additive; The electrolyte satisfies the following relationship: 0.0588≤A / (Z+C)≤0.7143; Wherein, A% represents the mass percentage content of the functional monomer in the electrolyte; C% represents the mass percentage content of the metal salt additive in the electrolyte; Z% represents the mass percentage content of the lithium salt in the electrolyte.

[0005] Optionally, in the electrolyte, the mass percentage content of the functional monomer is 1%≤A%≤10%; The mass percentage content of the metal salt additive in the electrolyte is 0.5%≤C%≤5%; The mass percentage content of the lithium salt in the electrolyte is 5%≤Z%≤25%.

[0006] Optionally, the electrolyte further comprises a diluent, and the electrolyte satisfies the following relationship: 0.00769≤C / [(Z / X)*Y] ≤ 0.1846; wherein X% represents the mass percentage content of the organic solvent in the electrolyte; Y% represents the mass percentage content of the diluent in the electrolyte.

[0007] Optionally, in the electrolyte, the mass percentage content of the organic solvent is 5%≤X%≤30%. The mass percentage content of the diluent is 40%≤Y%≤75%.

[0008] Optionally, the electrolyte satisfies the following condition: 0.3333≤Z / X≤3.

[0009] Optionally, the electrolyte satisfies the following relationship: 0.0004≤B / A≤0.05; wherein B% represents the mass percentage content of the initiator in the electrolyte.

[0010] Optionally, in the electrolyte, the mass percentage content of the initiator is 0.002%≤B%≤0.1%.

[0011] Optionally, the initiator comprises one or more of azobisisobutyronitrile, azobisisoheptyl nitrile, dimethyl azobisisobutyrate, benzoyl peroxide, t-butyl benzoyl peroxide, methyl ethyl ketone peroxide.

[0012] Optionally, the metal salt additive comprises one or more of bis(trifluoromethylsulfonylimide) magnesium, magnesium trifluoromethanesulfonate, bis(trifluoromethylsulfonyl) imide zinc, bis(trifluoromethylsulfonyl) imide sodium, bis(fluorosulfonyl) imide potassium, trifluoromethanesulfonylimide potassium, zinc trifluoromethanesulfonate, sodium trifluoromethanesulfinate.

[0013] Optionally, the functional monomer comprises one or more of N,N'-methylenebisacrylamide, N,N-dimethylacrylamide, ethoxylated trimethylolpropane triacrylate, pentaerythritol tetraacrylate, polyethylene glycol dimethacrylate, diethyl isopropenyl phosphonate, diethyl vinylphosphonate, diethyl 4-vinylbenzylphosphonate, 1-fluoromethylvinylsulfone, 1,3-divinyltetramethyldisiloxane, acrylonitrile, methyl methacrylate, polydipentaerythritol hexaacrylate, methylenebis(phenyl isocyanate), maleic anhydride, 1,4-butanediol diacrylate, ethyl 2-cyanoacrylate.

[0014] Optionally, the lithium salt comprises one or more of LiBF4, LiPF6, LiPF2O2, LiAsF6, LiClO4, LiSO3CF3, LiB(C2O4)2, LiBF2C2O4, LiFSI and LiTFSI.

[0015] Optionally, the organic solvent comprises one or more of vinyl carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl propyl carbonate, diphenyl carbonate, methyl acetate, methyl propionate, methyl butyrate, ethyl acetate, propyl acetate, ethyl butyrate, propyl propionate, γ-butyrolactone, 1,3-dioxolane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether and tetraethylene glycol dimethyl ether; and / or, the diluent comprises one or more of 2,2,2-trifluoroethyl-1,1,2,2-tetrafluoroethyl ether, bis(2,2,2-trifluoroethyl) ether, methyl nonafluorobutyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether.

[0016] Optionally, the additive further comprises an auxiliary additive, which comprises one or more of succinonitrile, adiponitrile, ethylene glycol bis(propionitrile) ether, 1,3,6-hexanetrione, glycerol trinitrile, 1,3-propanesultone, propenyl-1,3-sultone, ethylene sulfate, methanedisulfonate methylene, fluoroethylene carbonate and vinylene carbonate.

[0017] Optionally, in the electrolyte, the mass percentage of the auxiliary additive is 1%-15%.

[0018] In another aspect, the present application provides a gel electrolyte prepared by polymerization of the electrolyte.

[0019] In another aspect, the present application provides a lithium ion battery comprising the electrolyte or the gel electrolyte.

[0020] The present application has the following advantages: The electrolyte provided by the application has a functional monomer, a lithium salt and a metal salt additive. Through a polymerization reaction, the anion and the metal ion in the metal salt additive are strongly coordinated to change the solvation sheath, reduce the passivation layer formed by solvent decomposition, and then play a role in inhibiting side reactions and improving interface stability. In addition, the metal ion in the metal salt additive is coordinated and crosslinked with the functional monomer to induce in-situ gelation through the metal ion, forming a three-dimensional network structure. The three-dimensional network structure is closely attached to the electrode surface to form a protective film. The protective film can effectively isolate the contact between the electrolyte and the electrode active material, thereby reducing the side reaction between the electrolyte and the interface during the cycle process, inhibiting the dissolution of transition metals on the positive electrode side, and thus improving the cycle performance. Since the metal salt additive and the lithium salt are prone to decomposition and gas production at high temperatures, the functional monomer can improve the storage gas production. However, when the total content of the functional monomer relative to the metal salt additive and the lithium salt is relatively low, it is not enough to compensate for the gas production of the metal salt additive and the lithium salt. When the content is too high, the viscosity of the functional monomer is too large, and there is not enough lithium salt and metal salt additive to polymerize with the functional monomer to form a three-dimensional network structure of the polymer rich in metal ions, thus not conducive to improving the cycle performance. The inventors have found through a large number of verifications that when the mass percentage content A% of the functional monomer, the mass percentage content C% of the metal salt additive and the mass percentage content Z% of the lithium salt in the electrolyte satisfy the relationship 0.0588≤A / (Z+C)≤0.7143, the multiple components have a good synergistic effect, and thus better improve the storage and cycle performance of the lithium ion battery. DETAILED DESCRIPTION

[0021] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application.

[0022] The present application provides an electrolyte, comprising a functional monomer, a lithium salt, an additive, an organic solvent and an initiator, wherein the additive comprises a metal salt additive. The electrolyte satisfies the following relationship: 0.0588≤A / (Z+C)≤0.7143; wherein A% represents the mass percentage content of the functional monomer in the electrolyte; C% represents the mass percentage content of the metal salt additive in the electrolyte; Z% represents the mass percentage content of the lithium salt in the electrolyte.

[0023] Specifically, the electrolyte provided by the present application has a functional monomer, a lithium salt and a metal salt additive. Through a polymerization reaction, the anion (such as FSI -) with metal ions (such as Mg² + ) to change the solvation sheath, expel unstable DME (dimethyl ether, a commonly used solvent in lithium batteries, unstable in high salt concentration or strong coordination environment) molecules, reduce the passivation layer formed by solvent decomposition, and thus play a role in inhibiting side reactions and improving interface stability. In addition, the metal ions in the metal salt additive coordinate and crosslink with the functional monomer to initiate in-situ gelation through the metal ions, forming a three-dimensional network structure that tightly adheres to the electrode surface to form a protective film. This protective film can effectively isolate the electrolyte from the electrode active material, thereby reducing the side reactions between the electrolyte and the interface during the cycle process and inhibiting the dissolution of transition metals on the positive electrode side, thereby improving the cycle performance. Since the metal salt additive and lithium salt are prone to decomposition and gas production at high temperatures, the functional monomer can improve the storage gas production. However, when the content of the functional monomer is relatively low compared to the total content of the metal salt additive and lithium salt, it is not enough to compensate for the gas production of the metal salt additive and lithium salt. When the content is too high, the functional monomer has too high viscosity, and there is not enough lithium salt and metal salt additive to polymerize with the functional monomer to form a three-dimensional network structure of polymers rich in metal ions, thus not conducive to improving the cycle performance. The inventors have found through extensive verification that when the mass percentage content of the functional monomer A%, the mass percentage content of the metal salt additive C%, and the mass percentage content of the lithium salt Z% in the electrolyte satisfy the relationship 0.0588≤A / (Z+C)≤0.7143, the multiple components have a good synergistic effect, and thus better improve the storage and cycle performance of lithium-ion batteries.

[0024] In some embodiments, the mass percentage content of the functional monomer in the electrolyte is 1%≤A%≤10%; The mass percentage content of the metal salt additive in the electrolyte is 0.5%≤C%≤5%; The mass percentage content of the lithium salt in the electrolyte is 5%≤Z%≤25%.

[0025] Specifically, when the functional monomer mass percentage content satisfies 1%≤A%≤10%, a three-dimensional network with excellent cross-linking density can be formed after polymerization, which can effectively wrap the solvent, lithium salt and metal salt additives to form a gel state, reduce high-temperature gas production, and avoid excessive viscosity increase to hinder ion conduction. Similarly, when the mass percentage content of the metal salt additive satisfies the above limit condition, the metal ions can be fully coordinated with the polar groups of the functional monomers to enhance the network stability and ion conductivity, and will not decompose too much gas due to excessive content. When the mass percentage content of the lithium salt is in the limited range of 5%≤Z%≤25%, it is beneficial to ensure sufficient supply of lithium ions to maintain ion conductivity, while maintaining a suitable ratio with the functional monomer and the metal salt additive to ensure the synergistic effect of each component in the relationship 0.0588≤A / (Z+C)≤0.7143, stabilize the electrode interface, and improve the battery cycle and storage performance.

[0026] In some embodiments, the electrolyte further comprises a diluent, and the electrolyte satisfies the following relationship: 0.00769≤C / [(Z / X) *Y] ≤ 0.1846; wherein X% represents the mass percentage content of the organic solvent in the electrolyte; Y% represents the mass percentage content of the diluent in the electrolyte.

[0027] Specifically, when 0.00769≤C / [(Z / X) *Y]≤ 0.1846, the mass percentage content C% of the metal salt additive can be sufficient to match (Z / X) *Y, so that the metal ions effectively participate in the cross-linking of the functional monomers through coordination / ionic bonds, avoiding the problems of insufficient three-dimensional network stability or reduced ion conduction efficiency due to the mass percentage content of the metal salt additive being too low. In addition, if the mass percentage content of the metal salt additive is too high, the network may become too rigid due to excessive coordination of metal ions, inhibiting ion migration, or the amount of gas produced by self-decomposition of the metal salt additive may increase. If (Z / X)Y is too high (too much diluent or too high lithium salt concentration), the cross-linking efficiency of the functional monomers may be diluted or the lithium salt may be precipitated. Through experiments, it has been verified that when the mass percentage content of the metal salt additive and the mass percentage content Z% of the lithium salt, the mass percentage content X% of the organic solvent, and the mass percentage content Y% of the diluent satisfy 0.00769≤C / [(Z / X) *Y]≤ 0.1846, the relationship optimizes the ion conduction and network structure stability of the electrolyte by adjusting the ratio of C% to Z%, X%, and Y%, further optimizing the comprehensive performance of the battery.

[0028] In some embodiments, the mass percentage content of the organic solvent in the electrolyte is 5%≤X%≤30%; the mass percentage content of the diluent is 40%≤Y%≤75%.

[0029] Specifically, the organic solvent as a solvent of the functional monomer, lithium salt and metal salt needs to maintain a certain content to ensure that each component is fully dissolved and dispersed. When the content of the organic solvent is too low, the viscosity of the electrolyte is too high, the transmission of lithium ions is hindered, and the cycle performance is deteriorated. However, when the content of the organic solvent is too high (greater than 30%), the proportion of liquid components increases, the risk of gas production at high temperature rises, and the insufficient content of the diluent weakens the supporting effect on the functional monomer network.

[0030] The diluent is a solvent that can be mixed with a salt solution. It can reduce the concentration of the solution, thereby affecting the solubility of the salt. The addition of the diluent can make the electrolyte more close to the saturated state, reduce the free organic solvent, and when the free organic solvent is less, the side reaction between the organic solvent and the interface can be reduced. In the local high-salt system, the lithium salt is fully dissociated, and the anion can participate in the negative electrode film formation under the wrapping of the organic solvent. The ion conductivity and electrochemical stability of the interface film are more optimal, which is beneficial to improve the cycle performance of the battery.

[0031] The diluent in the range of 40%≤Y%≤75% can better adjust the viscosity of the electrolyte, promote the uniform diffusion of the functional monomer, and reduce the rigidity of the network after polymerization. At the same time, it forms an ion conduction channel with the lithium salt and metal salt additives. If the diluent is too much (greater than 75%), the content of the functional monomer also needs to be ensured to ensure that the two can be crosslinked and avoid a loose three-dimensional network. If the diluent is too little (less than 40%), the viscosity of the system may be too high, which hinders the ion migration.

[0032] In addition, in combination with C / [(Z / X) *Y], when the organic solvent X is low (less solvent) and the diluent Y is high (more diluent), (Z / X) *Y may increase, and the content of the metal salt additive needs to be increased accordingly to maintain the crosslinking effect of the metal ion on the network, so as to avoid the collapse of the network structure or the decrease of the ion conduction efficiency due to the change of the solvent environment, i.e. 5%≤X%≤30%, and the mass percentage content of the diluent is 40%≤Y%≤75%. This proportion range balances the solvent solubility and the physical supporting effect of the diluent, ensures that the gel electrolyte reduces gas production at high temperature and stabilizes the interface in the cycle.

[0033] In some embodiments, the mass percentage content of the organic solvent can be 5%, 8%, 10%, 15%, 20%, 25% or 30%; and the mass percentage content of the diluent can be 40%, 45%, 50%, 55%, 60%, 65%, 70% or 75%.

[0034] In some embodiments, the electrolyte satisfies the following conditions: 0.3333≤Z / X≤3.

[0035] Specifically, the physical meaning of Z / X is the content of lithium salt relative to the organic solvent. If the content of lithium salt relative to the organic solvent is too high, the electrolyte viscosity is large, affecting ion transmission, and the battery cycle performance is deteriorated. If the content of lithium salt relative to the organic solvent is too low, there are more free solvents, more side reactions, less anion film formation on the negative side, and cycle deterioration. If Z / X is less than 0.3333, it represents that the content of lithium salt is less and the content of organic solvent is more, which results in more free solvents. The free solvents will have side reactions with the electrode interface, deteriorating the battery cycle performance. If Z / X is greater than 3, it represents that the content of lithium salt is more and the content of organic solvent is less, which results in large electrolyte viscosity, causing ion transmission to be blocked and battery rate performance to be deteriorated.

[0036] In some embodiments, the electrolyte satisfies the following relationship: 0.0004≤B / A≤0.05; wherein B % represents the mass percentage content of the initiator in the electrolyte.

[0037] Specifically, the physical meaning of B / A is the content of initiator relative to functional monomer. If the content of initiator is too high, initiator residues are caused. If the content of initiator is too low, functional monomer residues are caused. Both monomer or initiator residues will deteriorate the battery cycle performance. If B / A is less than 0.0004, the amount of initiator is insufficient, the functional monomer is not fully polymerized, and the residual functional monomer that has not been polymerized is deposited on the positive and negative electrode surfaces, increasing the battery interface impedance and deteriorating the battery cycle performance. If B / A is greater than 0.05, the initiator is excessive, and the initiator residues in the electrolyte will release free radicals, causing the battery side reaction to intensify. Through a large number of preliminary experiments, it is found that when 0.0004≤B / A≤0.05, the initiator and functional monomer ratio is appropriate, which can not only ensure that the polymerization reaction proceeds smoothly to form a uniform and moderate cross-linked three-dimensional network, but also maintain the good ion conductivity and mechanical flexibility of the gel electrolyte, achieve low gas production at high temperature, stable electrode interface in the cycle, and optimize the comprehensive performance of the battery.

[0038] In some embodiments, the mass percentage content of the initiator in the electrolyte is 0.002%≤B%≤0.1%.

[0039] Specifically, the mass percentage content of the initiator can be 0.002%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, or 0.1%.

[0040] In some embodiments, the initiator includes one or more of azobisisobutyronitrile (AIBN), azobisisoheptyl nitrile, dimethyl azobisisobutyrate, benzoyl peroxide, t-butyl benzoyl peroxide, and methyl ethyl ketone peroxide.

[0041] In some embodiments, the metal salt additive includes one or more of bis(trifluoromethanesulfonimide) magnesium (Mg(TFSI)2), magnesium trifluoromethanesulfonate, bis(trifluoromethylsulfonyl) imide zinc, bis(trifluoromethylsulfonyl) imide sodium, bis(fluorosulfonyl) imide potassium, trifluoromethanesulfonimide potassium, trifluoromethanesulfonate zinc, sodium trifluoromethanesulfinate.

[0042] Specifically, the above metal salt additive contains magnesium, zinc, sodium, potassium metal cations, and trifluoromethanesulfonimide, trifluoromethanesulfonic acid and other anions. The metal cations can be combined with the polar groups (such as carboxyl, hydroxyl, phosphate) in the functional monomer through coordination or ionic bond, as a cross-linking node to promote the polymerization of the functional monomer to form a three-dimensional network structure, enhance the stability of the gel electrolyte, and the anion part can cooperate with the lithium salt anion to improve the ionic conductivity of the electrolyte. At the same time, part of the metal ions can also participate in the construction of the electrode interface film to generate a more stable composite film, inhibit the dissolution of transition metals and the growth of lithium dendrites in the negative electrode, and thus improve the cycle and high-temperature storage performance of the battery.

[0043] In some embodiments, the functional monomer includes one or more of N,N'-methylenebisacrylamide, N,N-dimethylacrylamide, ethoxylated trimethylolpropane triacrylate, pentaerythritol tetraacrylate, polyethylene glycol dimethacrylate, diethyl isopropenyl phosphonate, diethyl vinylphosphonate, diethyl 4-vinylbenzylphosphonate, 1-fluoromethyl vinyl sulfone, 1,3-divinyl tetramethyldisiloxane, acrylonitrile, methyl methacrylate, polydipentaerythritol hexaacrylate, methylenebis(phenyl isocyanate), maleic anhydride, 1,4-butanediol diacrylate, and ethyl 2-cyanoacrylate.

[0044] Specifically, the monomer containing carbon-carbon double bond (such as acrylamide, acrylate) undergoes free radical polymerization under the action of initiator to form long-chain polymer, and the multi-functional monomer (such as ethoxylated trimethylolpropane triacrylate, pentaerythritol tetraacrylate) constructs a three-dimensional network through cross-linking reaction to fix the electrolyte components; the polar groups (such as diethyl vinylphosphonate, 1-fluoromethyl vinyl sulfone, acrylonitrile) can be coordinated with the cations (Mg 2+ , Zn 2+ ) of the metal salt additive to strengthen the network structure, and be adsorbed on the electrode surface through electrostatic action to form a stable protective film to inhibit the dissolution of transition metals and side reactions; the polyethylene glycol segment (such as polyethylene glycol dimethacrylate) provides network flexibility to reduce internal resistance; the isocyanate group (such as methylenebisphenyl isocyanate) can react with the groups containing active hydrogen to further cross-link and improve the interfacial compatibility.

[0045] In some embodiments, the lithium salt comprises one or more of LiBF4, LiPF6, LiPF2O2, LiAsF6, LiClO4, LiSO3CF3, LiB(C2O4)2, LiBF2C2O4, LiFSI, and LiTFSI.

[0046] Specifically, the above-mentioned lithium salt mainly serves as a source of lithium ions in the electrolyte, and improves the battery performance through its own characteristics and synergistic effect with other components; LiPF6 has good solubility and high ionic conductivity in commonly used carbonate solvents, but is prone to decomposition and gas generation at high temperatures; the anions of LiFSI and LiTFSI have strong electron-withdrawing groups, which can increase the ion transference number and form a more stable SEI film, thereby inhibiting the interface side reaction; LiB(C2O4)2 can form a passivation film rich in Li2CO3 and LiF on the electrode surface, thereby enhancing the interface stability; in a mixed lithium salt system, different anions can synergistically optimize the performance of the electrolyte, such as providing lithium ions quickly through LiPF6, improving high-temperature stability through LiTFSI, and jointly ensuring efficient ion conduction in the three-dimensional network formed by the polymerization of functional monomers, thereby helping to improve the battery cycle and storage performance.

[0047] In some embodiments, the organic solvent comprises one or more of vinyl carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl propyl carbonate, diphenyl carbonate, methyl acetate, methyl propionate, methyl butyrate, methyl acetate, ethyl acetate, propyl acetate, ethyl butyrate, propyl propionate, γ-butyrolactone, 1,3-dioxolane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether; and / or, the diluent comprises one or more of 2,2,2-trifluoroethyl-1,1,2,2-tetrafluoroethyl ether, bis(2,2,2-trifluoroethyl) ether, methyl nonafluorobutyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether.

[0048] Specifically, the high dielectric constant solvents in the organic solvent (such as vinyl carbonate, propylene carbonate) can effectively dissolve the lithium salt, promote the dissociation of the lithium salt into free ions, and improve the ionic conductivity of the electrolyte, while forming hydrogen bonds with the polar groups (such as hydroxyl, carboxyl) of the functional monomers, thereby enhancing the compatibility of the solvent with the polymer network and further improving the stability of the gel structure.

[0049] The low viscosity solvents in the organic solvent (such as dimethyl carbonate, methyl ethyl carbonate) can reduce the overall viscosity of the electrolyte, promote the uniform dispersion of the functional monomers, lithium salt, and metal salt additives, and ensure that the polymerization reaction proceeds fully; at the same time, the low viscosity solvents can improve the wettability of the gel electrolyte and enhance the penetration ability of the electrode pores.

[0050] High-boiling solvents in organic solvents (such as diphenyl carbonate) improve the high-temperature stability of the electrolyte, reduce the production of solvent gas at high temperatures, and synergistically inhibit the loss of liquid components with the functional monomer network.

[0051] Fluoroether diluents in diluents (such as 2,2,2-trifluoroethyl-1,1,2,2-tetrafluoroethyl ether) do not participate in the polymerization reaction, but can adjust the electrolyte polarity, reduce the solvent shell thickness of solvated lithium ions, promote Li + desolvation, and improve the migration rate; at the same time, its chemical inertness can reduce side reactions with the electrode, especially at high temperatures, and further reduce the risk of gas production in cooperation with the functional monomer network.

[0052] Organic solvents provide sufficient polarity to dissolve lithium salts and metal salts, and diluents reduce system viscosity and increase free volume, which is beneficial to ion migration; The fluorinated structure of the diluent interacts with the polar groups (such as phosphate groups and cyano groups) in the functional monomer through van der Waals forces, enhancing the physical binding of the gel network to the solvent and reducing the movement of liquid components.

[0053] Organic solvents serve as reaction media for the polymerization of functional monomers, ensuring uniform growth of polymer chains; diluents, through physical filling, avoid excessive network densification that hinders ion conduction, and through "steric hindrance", inhibit excessive functional monomer segment curling, maintaining the openness of network pores.

[0054] In summary, the combination of organic solvents and diluents, through multiple actions such as dissolution, dispersion, viscosity adjustment, and interface optimization, synergistically forms a performance-balanced gel electrolyte with functional monomers, lithium salts, and metal salt additives, achieving the dual goals of high-temperature low-gas production and cycle stability.

[0055] In some embodiments, the additive further includes an auxiliary additive, which includes one or more of butanedinitrile, hexanedinitrile, ethylene glycol bis(propionitrile) ether, 1,3,6-hexanetristitrate, glycerol trinitrate, 1,3-propane sulfite, propylene-1,3-sulfite, ethylene sulfate, methane disulfite, fluoroethylene carbonate, and vinylene carbonate.

[0056] The addition of the above auxiliary additive, in cooperation with the three-dimensional network formed by the functional monomer and the cross-linking effect of the metal salt additive, collectively builds a stable interface protection film, reduces high-temperature gas production and side reactions during the cycle process, and achieves comprehensive improvement of battery performance.

[0057] In some embodiments, the mass percentage content of the auxiliary additive in the electrolyte is 1%-15%.

[0058] Specifically, the mass percentage of the auxiliary additive can be 1%, 3%, 5%, 8%, 10%, 12% or 15%.

[0059] Another embodiment of the present application provides a gel electrolyte prepared by polymerization of the electrolyte.

[0060] Specifically, in the present application, the process of polymerizing the electrolyte to obtain the gel electrolyte, the functional monomer containing double bonds (such as acrylate, acrylamide) undergoes free radical polymerization under the action of an initiator, and a three-dimensional polymer network is formed through a crosslinking agent (such as N,N'-methylene bisacrylamide), the lithium salt, metal salt additive, organic solvent and diluent are wrapped in the network pores, the liquid components are physically fixed, and are converted into a gel state.

[0061] The protective film formed by the three-dimensional network isolates the electrode and the electrolyte, and inhibits the dissolution of the transition metal of the positive electrode and the growth of lithium dendrites of the negative electrode; the composite interface film (Li-M-O-F) constructed by the metal ions has both ion conductivity and mechanical strength, and reduces the increase of the interface impedance in the cycle.

[0062] The lithium salt (such as LiTFSI or LiFSI) provides sufficient Li + The diluent adjusts the network porosity to avoid excessive densification, ensures the smoothness of the ion migration path, and the metal salt optimizes the solvation structure through coordination to improve the Li + migration number.

[0063] Another embodiment of the present application provides a lithium ion battery comprising the electrolyte or the gel electrolyte described above.

[0064] Specifically, the lithium ion battery uses the gel electrolyte described in the present application, and the gel electrolyte comprises the electrolyte described in the present application, in which the functional monomer is polymerized to form a three-dimensional network structure, which cooperates with the lithium salt, the metal salt additive and the auxiliary additive to form a protective film on the electrode surface, reduce side reactions, inhibit the dissolution of transition metal, and reduce gas production at high temperature by limiting the liquid components; at the same time, the reasonable component ratio ensures the ion conduction efficiency, and finally realizes the significant improvement of the cycle performance and high-temperature storage performance of the battery.

[0065] In some embodiments, the lithium ion battery comprises a positive electrode, a negative electrode and a separator, the positive electrode comprises a positive electrode active material layer, the positive electrode active material layer comprises a positive electrode active material, and the positive electrode active material comprises one or more of transition metal lithium oxide, lithium iron phosphate, lithium manganate, lithium manganese iron phosphate and lithium vanadium phosphate.

[0066] The chemical formula of the transition metal lithium oxide is Li 1+x Ni y Co zM (1-y-z) O2; wherein 0.1≤x≤1, 0≤y≤1, 0≤z≤1, and 0≤y+z≤1. wherein M is selected from one or more of Mg, Zn, Ga, Ba, Al, Fe, Cr, Sn, V, Mn, Sc, Ti, Nb, Mo, Zr.

[0067] The negative active material is pure silicon particles.

[0068] In the present application, the negative current collector is not particularly limited as long as the purpose of the present application can be achieved, and can be, for example, a copper foil, a copper alloy foil, a nickel foil, a stainless steel foil, a titanium foil, a nickel foam, a copper foam, or a composite current collector.

[0069] In some preferred embodiments, the negative current collector comprises a copper foil.

[0070] In some embodiments, the negative electrode further comprises a negative active material layer disposed on at least one side surface of the current collector, the negative active material layer further comprising a negative conductive agent, a negative binder, a thickening agent, and a solvent.

[0071] wherein the negative conductive agent comprises at least one of natural graphite, artificial graphite, acetylene black, needle coke, carbon nanotubes, graphene, and other carbon materials. The negative binder comprises, for example, a butadiene styrene latex, and the thickening agent comprises CMC, and the solvent comprises deionized water.

[0072] In some embodiments, the positive electrode comprises a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector, the positive active material layer comprising a positive active material.

[0073] In the present application, the type of positive current collector is not particularly limited and can be any known material suitable for use as a positive current collector. In one embodiment, the positive current collector comprises aluminum, stainless steel, a nickel plating layer, titanium, tantalum metal materials, and carbon cloth, carbon paper carbon materials.

[0074] In one embodiment, the positive current collector is a metal material.

[0075] In some embodiments, the positive active material layer further comprises a positive conductive agent, a positive binder, and a solvent.

[0076] In some embodiments, the type of positive conductive agent mentioned in the present application is not limited and any known conductive agent can be used.

[0077] In some embodiments, the positive electrode conductive agent mentioned in the present application includes at least one of natural graphite, artificial graphite, acetylene black, needle coke, carbon nanotubes, graphene, and other carbon materials, and in one of the embodiments, the kind of the positive electrode binder mentioned in the present application is not limited, and any known positive electrode binder can be used.

[0078] In some embodiments, the positive electrode binder includes at least one of polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, nitrocellulose.

[0079] In the lithium ion battery mentioned in the present application, in order to prevent short circuit, a separator is usually arranged between the positive electrode and the negative electrode. The material and shape of the separator are not particularly limited, as long as they do not significantly impair the effects of the present application.

[0080] In some embodiments, the separator includes a substance in a porous sheet or non-woven cloth form with excellent liquid retention, and the like, and the material of the separator includes resin or glass fiber separator materials, including but not limited to polyolefin, aromatic polyamide, polytetrafluoroethylene, polyether sulfone, and the like.

[0081] In some embodiments, the lithium ion battery can include an outer package that can be used to package the electrode assembly and the electrolyte.

[0082] In some embodiments, the outer package of the lithium ion battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell. The outer package of the lithium ion battery can also be a soft package, such as a bag-type soft package.

[0083] The material of the soft package can be plastic, and as plastic, polypropylene, polybutylene terephthalate, and polybutylene succinate can be listed.

[0084] The shape of the lithium ion battery mentioned in the present application is not particularly limited, and it can be cylindrical, square, or any other shape.

[0085] On the other hand, one embodiment of the present application provides an electric device including the lithium ion battery mentioned above.

[0086] The electric device mentioned above can include mobile devices (such as mobile phones, notebook computers), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks), electric trains, ships and satellites, energy storage systems, but is not limited thereto.

[0087] Table 1 The application is further illustrated by the following examples.

[0088] Example 1 This example is used to illustrate the electrolyte, gel electrolyte and lithium ion battery disclosed by the application, which comprises the following operation steps: Preparation of positive electrode sheet The positive electrode active material lithium cobaltate, the positive electrode conductive agent acetylene black (Super P) and the polyvinylidene fluoride (PVDF) binder are mixed uniformly in a mass ratio of 97:1.5:1.5, and are uniformly dispersed with 1-methyl-2-pyrrolidone (NMP) to prepare a uniform positive electrode slurry. After the mixed slurry is coated on both sides of the aluminum foil current collector, baking, rolling, and sheet cutting, a positive electrode sheet is obtained. Preparation of negative electrode sheet The negative electrode active material pure silicon particles, the negative electrode conductive agent acetylene black (Super P), the thickening agent CMC and the negative electrode binder SBR are mixed uniformly in a mass ratio of 94:2:1.2:2.8, and are uniformly dispersed with deionized water to prepare a uniform negative electrode slurry. After the mixed slurry is coated on both sides of the copper foil current collector, baking, rolling, and sheet cutting, a negative electrode sheet is obtained. Preparation of electrolyte (a) The organic solvent dimethyl carbonate (DMC), the diluent 1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), and the lithium salt LiFSI are dehydrated with a molecular sieve and prepared for use.

[0089] (b) The solvent, lithium salt, metal salt additive, additive, monomer, and initiator are sequentially added in the proportions (addition amount in Table 1) to obtain a liquid electrolyte. Preparation of gel electrolyte and lithium ion battery The prepared positive electrode sheet, separator and negative electrode sheet are stacked in order with the separator between the positive and negative electrode sheets, and then wound and tab welded to obtain a bare core. The bare core is placed in an aluminum plastic film, and liquid electrolyte is injected and packaged. After the battery is packaged, it is subjected to hot pressing at 60°C and 0.3Mpa for 12H to polymerize the liquid electrolyte into a gel electrolyte. After hot pressing and polymerization, formation, capacity grading and aging are performed to obtain a lithium ion battery.

[0090] Examples 2-65 Example 2-65 was used to illustrate an electrolyte, gel electrolyte and lithium ion battery according to the present disclosure, including most of the operations in Example 1, except that: The functional monomer type, functional monomer mass percentage, initiator type, initiator mass percentage, metal salt additive mass percentage, metal salt additive type, auxiliary additive type, auxiliary additive mass percentage, organic solvent mass percentage, diluent mass percentage, and lithium salt mass percentage in Example 2-65 were all according to the corresponding components in Table 1.

[0091] Comparative Example 1 Comparative Example 1-36 was used to compare an electrolyte, gel electrolyte and lithium ion battery according to the present disclosure, including most of the operations in Example 1, except that: The functional monomer type, initiator type, metal salt additive type, organic solvent type, diluent type, lithium salt type, and corresponding additive amount in Comparative Example 1-36 were all according to the corresponding components in Table 1.

[0092] Performance Test The above-prepared Example 1-65 and Comparative Example 1-36 were subjected to the following performance tests: The lithium ion batteries prepared in the above examples and comparative examples were subjected to the following tests.

[0093] 70℃ Storage Performance Test The lithium ion batteries prepared in the above examples and comparative examples were charged to the cut-off voltage at a rate of 1C at 25℃, with a cut-off current of 0.025C, and were allowed to stand for 5 min. The thickness H1 of the lithium ion battery was then measured. The lithium ion battery was then stored at 70℃ for 30 days, and the thickness H2 of the lithium ion battery was measured after the storage.

[0094] Thickness Expansion Rate = [(H2-H1) / H1] x 100%.

[0095] 0℃ Cycle Performance Test The lithium ion batteries prepared in the above examples and comparative examples were subjected to charge-discharge cycling at 0℃ at a rate of 1C / 1C within the charge-discharge cut-off voltage range. The discharge capacity in the first week was measured as C1, and the discharge capacity in the 600th cycle was measured as C2. The cycle capacity retention rate R2 in the 600th week was calculated as C2 / C1.

[0096] 45℃ Cycle Performance Test The lithium ion batteries prepared in each of the above examples and comparative examples were subjected to charge-discharge cycling at 45℃ within the charge-discharge cut-off voltage range at a rate of 1C / 1C, the discharge capacity in the first week was counted as X1, and the discharge capacity in the 600th cycle was counted as X2; the capacity in the 600th week divided by the capacity in the first week gave the cycle capacity retention rate Y2=X2 / X1 in the 600th week.

[0097] The test results obtained were filled in Table 2.

[0098] Table 2 As can be seen from the test results in Table 2, the overall performance of Example 1-65 (70℃ thickness expansion rate, 0℃ cycle 600th week capacity retention rate, and 45℃ cycle 600th week capacity retention rate) is better than that of Comparative Example 1-32; As can be seen from the test results of Comparative Example 2-3 and Comparative Example 6-7, when the functional monomer and the initiator do not exist at the same time, the liquid electrolyte cannot form a gel state, and the residual functional monomer or initiator deteriorates the battery performance. According to the test results of Example 1-5 and Comparative Example 10-11, as the content of the functional monomer increases, the high-temperature storage performance improves, which is because after the liquid electrolyte is thermally polymerized after the content of the functional monomer increases, a gel state is formed, the liquid component is reduced, the decomposition gas is reduced at high temperature, and as the content of the functional monomer increases, the cycle performance first improves and then deteriorates. The first improvement is because the functional monomer can mix with the lithium salt at the positive and negative electrode interface to polymerize into a three-dimensional network structure to form a protective film, reduce the side reaction between the electrolyte and the interface during the cycle process, and inhibit the dissolution of transition metals on the positive electrode side, thus improving the cycle performance. However, as the content of the monomer increases, the viscosity of the electrolyte increases, and the lithium ion transmission is blocked, and the cycle performance deteriorates. When the content of the functional monomer is less than 1%, it is not enough to form a gel polymer from the liquid electrolyte, and the cycle performance and storage performance of the battery are poor. When the content of the functional monomer is more than 10%, the viscosity of the electrolyte increases sharply, and the rate performance of the battery deteriorates; According to the test results of Examples 6-10 and Comparative Examples 12-13, as the content of the initiator increases, the battery performance first improves and then deteriorates; the initiator can release free radicals at high temperatures, accelerating the polymerization of monomers; when the content of the initiator is insufficient, the monomers cannot be fully polymerized, and the residual monomers will deposit on the positive and negative electrodes, which will deteriorate the battery performance; when the content of the initiator is too high, the initiator will be left over, the initiator does not have electrochemical activity, and instead, the release of free radicals by the initiator will intensify the side reactions inside the battery, deteriorating the battery performance; when the content of the initiator is less than 0.002%, there is more residual functional monomer, and when the content of the initiator is greater than 0.1%, the initiator is not fully consumed, which will cause the initiator to be left over, thus significantly deteriorating the battery performance; According to the test results of Comparative Example 4, Comparative Examples 14-15, and Examples 11-15, the addition of metal salt additives alone improves the cycle performance, but the metal salt additives are prone to decomposition and gas production at high temperatures, and as the content of the metal salt additives increases, the high-temperature storage performance deteriorates, and the cycle performance first improves and then deteriorates; As a carrier, the metal salt additive greatly improves the solubility of lithium salt in the electrolyte, and the anion of the lithium salt participates in the construction of the Li + solvated structure of the electrolyte, and the multivalent Mg, K, Na, and Zn metal ions on the SEI surface can produce electrostatic attraction to the anion of the lithium salt, promoting the formation of an inorganic SEI (rich in nitride and fluoride), which realizes uniform deposition of lithium and avoids serious side reactions with the electrolyte, thus significantly improving the cycle performance; the metal salt is unstable at high temperatures, especially when the temperature exceeds 60°C, and is prone to decomposition and gas production, thus the storage performance deteriorates as the content of the metal salt additive increases; compared with Comparative Example 5 and Example 3, when the content of the metal salt is less than 0.1%, there are more side reactions at the interface, and the cycle performance deteriorates; when the content of the metal salt is greater than 5%, the viscosity of the electrolyte increases, and the ion transport is hindered, thus the cycle performance deteriorates; according to Comparative Examples 4, 5, 8, 9, and Example 3, only when the monomer and the metal lithium salt additive are used together can the best synergistic effect be achieved.

[0099] According to the test results of Comparative Examples 16-17 and Examples 16-21, as the content of the organic solvent increases, the storage performance deteriorates, the 0°C cycle improves, and the high-temperature cycle first improves and then deteriorates; this is because the organic solvent is prone to decomposition and gas production at high-temperature storage, thus the high-temperature storage deteriorates as the content of the organic solvent increases; the increase in the content of the organic solvent reduces the viscosity of the electrolyte and more completely dissociates the lithium salt, thus improving the low-temperature cycle performance; the improvement in the high-temperature cycle performance is also based on the reduction in the viscosity of the electrolyte and the increase in the ionic conductivity, but as the content of the organic solvent increases, the reduction side reaction at the negative electrode intensifies, thus the high-temperature cycle deteriorates; Comparative Examples 16-17 further compared with Example 3, when the organic solvent content is less than 5% (Comparative Example 16), the electrolyte viscosity is too high, the lithium ion transmission is blocked, and the cycle performance is deteriorated, when the organic solvent content is greater than 30% (Comparative Example 17), the solvent decomposes to produce gas at high temperature, and the reduction side reaction at the negative electrode side is intensified and deteriorated at high temperature cycle, but as the organic solvent content increases, the electrolyte viscosity decreases, and the low-temperature cycle performance improves.

[0100] According to Comparative Examples 18-19 and Examples 22-25, as the diluent content increases, the storage performance deteriorates, the diluent itself is prone to decomposition at high temperature, leading to increased gas production, and as the diluent content increases, the 0°C cycle deteriorates; compared with Example 3, with the addition of diluent, the electrolyte viscosity increases, the low-temperature cycle performance deteriorates, the high-temperature cycle is better based on anion film stability, and the trend is first improved and then deteriorated. When the diluent is too little, less than 40% (Example 18), the electrolyte anion film is less, the interface film is unstable, and the cycle performance is poor; when the diluent is too much, greater than 75% (Example 19), the electrolyte viscosity increases, the ion transmission is blocked, and the cycle performance deteriorates, and the storage is also deteriorated; According to Comparative Examples 20-21 and Examples 26-30, lithium salt is prone to decomposition to produce gas at high temperature, and as the lithium salt content increases, the high-temperature storage produces more gas; as the lithium salt content increases, the ion transference number increases, which is beneficial to ion transmission and can improve the cycle rate; but as the lithium salt content increases, the electrolyte viscosity increases, leading to blocked ion transmission, thus deteriorating the cycle performance. When the lithium salt content is too high, greater than 25% (Comparative Example 21), the electrolyte viscosity will increase, the ion transmission will be blocked, and the cycle performance will deteriorate, and the high-temperature storage will also deteriorate; when the lithium salt content is too low, less than 5% (Comparative Example 20), the electrolyte ion conductivity will decrease, and the cycle performance will also be poor; According to the comparison of Examples 1-30 and Comparative Examples 22-25, too high initiator content will result in initiator residue, and too low initiator content will result in functional monomer residue, and both functional monomer and initiator residues will deteriorate the battery cycle performance, and through testing, it is found that when B / A satisfies 0.0004≤B / A≤0.05, the functional monomer and the initiator can play the best synergistic effect; According to the comparison of Examples 1-30 and Comparative Examples 30-31, too high Z / X represents that the lithium salt content is too large relative to the organic solvent content, the electrolyte viscosity is higher, and the increase of the diluent will also result in less free solvent and greater ion transmission resistance, that is, (Z / X) * Y can represent the ion transmission ability and local high salt characteristics of the electrolyte, the larger the value, the higher the lithium salt concentration of the electrolyte, and the worse the battery rate performance, and the metal salt additive can change the solvation structure, the metal salt additive acts as a carrier, greatly improves the solubility of lithium salt in the electrolyte, and the anion of lithium salt participates in the construction of Li +The multivalent Mg, K, Na, Zn ions on the SEI surface can produce electrostatic attraction to the anion of the lithium salt, promote the formation of inorganic SEI, and thus realize uniform deposition of lithium and avoid serious side reactions with the electrolyte, so the cycle performance is obviously improved. When the relative (Z / X) *Y content of the metal lithium salt is too low, the solvation structure cannot be changed to improve the cycle performance, and more than 0.00769 is required to achieve better synergistic effect. According to examples 1-30 and comparative examples 32-35, the metal salt additive and the lithium salt are both prone to decomposition and gas production at high temperatures, and the functional monomer can improve the storage gas production, so when the total content of the functional monomer relative to the metal salt additive and the lithium salt is relatively low, it is not enough to compensate for the gas production of the metal salt additive and the lithium salt. When the equivalent content is too high, the viscosity of the functional monomer is too large, and there is not enough lithium salt and metal salt additive to polymerize with the monomer to form a three-dimensional network structure of the polymer rich in metal ions, which is not conducive to improving the cycle performance. When 0.0588≤A / (Z+C)≤0.7143 is satisfied, the best synergistic effect can be achieved. According to examples 58-65 and comparative example 36, the auxiliary additive is important for the stability of the initial SEI film. Without other auxiliary film-forming additives, the initial interface stability is poor. According to the test results of examples 31-57, when the functional monomer, initiator, and metal salt additive are other types of functional monomers, initiators, and metal salt additives defined in the application, the same synergistic effect can be achieved.

[0101] The above only describes the preferred embodiments of the application and is not intended to limit the application. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. An electrolyte, characterized in that: The method comprises a functional monomer, a lithium salt, an additive, an organic solvent and an initiator, wherein the additive comprises a metal salt additive; The electrolyte satisfies the following relationship: 0.0588≤A / (Z+C)≤0.7143; Wherein, A% represents the mass percentage of the functional monomer in the electrolyte; C% represents the mass percentage of metal salt additive in the electrolyte; Z% represents the mass percentage of lithium salt in the electrolyte.

2. The electrolyte according to claim 1, characterized in that In the electrolyte, the mass percentage of the functional monomer is 1%≤A%≤10%; The mass percentage of the metal salt additive in the electrolyte is 0.5%≤C%≤5%; The mass percentage of the lithium salt in the electrolyte is 5%≤Z%≤25%.

3. The electrolyte according to claim 1, characterized in that The electrolyte further includes a diluent, and the electrolyte satisfies the following relationship: 0.00769≤C / [(Z / X)*Y] ≤0.1846; Wherein, X% represents the mass percentage of the organic solvent in the electrolyte; Y% represents the mass percentage of the diluent in the electrolyte.

4. The electrolyte according to claim 3, characterized in that In the electrolyte, the mass percentage of the organic solvent is 5%≤X%≤30%; The mass percentage of the diluent is 40%≤Y%≤75%.

5. The electrolyte according to claim 3, characterized in that The electrolyte meets the following conditions: 0.3333≤Z / X≤3.

6. The electrolyte according to claim 1, characterized in that The electrolyte satisfies the following relationship: 0.0004≤B / A≤0.05; Wherein, B% represents the mass percentage of the initiator in the electrolyte.

7. The electrolyte according to claim 6, characterized in that In the electrolyte, the mass percentage of the initiator is 0.002%≤B%≤0.1%.

8. The electrolyte according to claim 6, characterized in that The initiator includes one or more of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, benzoyl peroxide, tert-butyl benzoyl peroxide, and methyl ethyl ketone peroxide.

9. The electrolyte according to claim 1, characterized in that The metal salt additive includes one or more of bis(trifluoromethanesulfonyl imide) magnesium, magnesium trifluoromethanesulfonate, bis(trifluoromethylsulfonyl)imide zinc, bis(trifluoromethylsulfonyl)imide sodium, bis(fluorosulfonyl)imide potassium, trifluoromethanesulfonyl imide potassium, zinc trifluoromethanesulfonate, and sodium trifluoromethanesulfinate.

10. The electrolyte according to claim 1, characterized in that The functional monomers include one or more of N,N'-methylenebisacrylamide, N,N-dimethylacrylamide, ethoxylated trimethylolpropane triacrylate, pentaerythritol tetraacrylate, polyethylene glycol dimethacrylate, diethyl isopropenyl phosphate, diethyl vinyl phosphate, diethyl 4-vinylbenzylphosphonate, 1-fluoromethyl vinyl sulfone, 1,3-divinyltetramethyldisiloxane, acrylonitrile, methyl methacrylate, polydipentaerythritol hexaacrylate, methylene bis(phenyl isocyanate), maleic anhydride, 1,4-butanediol diacrylate, and ethyl 2-cyanoacrylate.

11. The electrolyte according to claim 1, characterized in that The lithium salt includes one or more of LiBF4, LiPF6, LiPF2O2, LiAsF6, LiClO4, LiSO3CF3, LiB(C2O4)2, LiBF2C2O4, LiFSI and LiTFSI.

12. The electrolyte according to claim 3, characterized in that The organic solvent includes one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methylpropyl carbonate, diphenyl carbonate, methyl acetate, methyl propionate, methyl butyrate, methyl acetate, ethyl acetate, propyl acetate, ethyl butyrate, propyl propionate, γ-butyrolactone, 1,3-dioxolane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether and tetraethylene glycol dimethyl ether; and / or the diluent includes one or more of 2,2,2-trifluoroethyl-1,1,2,2-tetrafluoroethyl ether, bis(2,2,2-trifluoroethyl) ether, methyl nonafluorobutyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether.

13. The electrolyte according to claim 1, characterized in that The additives further include auxiliary additives, which include one or more of succinonitrile, adiponitrile, ethylene glycol bis(propionitrile) ether, 1,3,6-hexanetrinitrile, glycerol trinitrile, 1,3-propane sultone, propenyl-1,3-sultone, vinyl sulfate, methylene methanedisulfonate, fluoroethylene carbonate and vinylene carbonate.

14. The electrolyte according to claim 13, characterized in that In the electrolyte, the mass percentage of the auxiliary additive is 1%-15%.

15. A gel electrolyte, characterized in that: The gel electrolyte is prepared by polymerization reaction of the electrolyte according to any one of claims 1 to 14.

16. A lithium ion battery, characterized in that: The electrolyte according to any one of claims 1 to 14, or the gel electrolyte according to claim 15.

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