Electrolyte, battery, and electric device

Abstract

An electrolyte, a battery, and an electric device. The electrolyte comprises an organic solvent, a lithium salt, and an additive, the organic solvent comprises an ionic liquid, the ionic liquid comprises a cation and an anion, and the cation comprises one or more of the following structural formulas: (I)-(V). In structural formulas I-V, R1-R10 each independently comprise one or more of C1-C8 alkyl or a C1-C8 alkyl isomer; and the anion comprises one or more of the following structural formulas: (VI)-(X). By introducing the ionic liquid, a large number of anions are driven to enter a Li+ solvation sheath, a solvation structure is regulated and controlled by means of a series of weak interactions, and multiple regulation and control of an interface are completed under the condition that fluorinated anions dominate the solvation structure, such that the solvation structure of Li+ and a derived interface can be effectively adjusted, the service temperature range of a battery is widened, the cycle life of the battery is prolonged, the energy density and the power density of the battery are increased, and the safety of the battery is improved.

Description

Electrolyte, battery and electric device

[0001] The present application is based on the Chinese patent application No. 202410897386.4, filed on July 4, 2024, entitled "Electrolyte, battery and electric device", and claims priority thereto. TECHNICAL FIELD

[0002] The present application relates to the technical field of battery, in particular to an electrolyte, a battery and an electric device. BACKGROUND

[0003] Currently, the commercial electrolyte of the battery has the problem of unstable oxidative decomposition at high cut-off voltage, which hinders the further development of the battery to high voltage and high energy density. SUMMARY

[0004] In view of the problem of unstable oxidative decomposition of the electrolyte at high cut-off voltage, the present application provides an electrolyte, a battery and an electric device.

[0005] The technical solution adopted by the present application to solve the above technical problems is as follows:

[0006] The first aspect of the present application provides an electrolyte, comprising an organic solvent, a lithium salt and an additive, wherein the organic solvent comprises an ionic liquid, the ionic liquid comprises one or more combinations of cations and anions, the cations comprise one or more of the following structural formulas:

[0007] wherein R1-R10 in structural formula I-V are each independently one or more of C1-C8 alkyl, C1-C8 alkyl isomers;

[0008] The anions comprise one or more of the following structural formulas:

[0009] Optionally, the percentage content of the ionic liquid in the total mass of the electrolyte is 2%-95%.

[0010] Optionally, the organic solvent comprises an ether solvent, and the ether solvent comprises one or more of 2-dimethoxyethane, ethylene glycol dimethyl ether, dimethoxydimethyl ether, diethylene glycol dimethyl ether, 1,3-dioxolane, triethylene glycol monoethyl ether, tetrahydrofuran, 2-methyl-tetrahydrofuran.

[0011] Optionally, the percentage content of the ether solvent in the total mass of the electrolyte is 2%-95%.

[0012] Optionally, the lithium salt comprises one or more of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium trifluoromethylsulfonate, lithium bis(trifluoromethylsulfonyl)imide, lithium bisfluorosulfonylimide, lithium trifluoromethylsulfonyl-N-perfluorobutylsulfonylimide, lithium fluorosulfonyl-N-perfluorobutylsulfonylimide, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium difluorophosphate, lithium nitrate.

[0013] Optionally, the lithium salt accounts for 1-60% of the total mass of the electrolyte.

[0014] Optionally, the additive comprises one or more of fluoroethylene carbonate, 1,3-propane sultone, vinylene carbonate, ethylene sulfate, lithium nitrate, lithium borate, lithium difluoro(oxalato)borate.

[0015] Optionally, the additive accounts for 0.1-20% of the total mass of the electrolyte.

[0016] The second aspect of the present application provides a battery comprising a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte as described above.

[0017] Optionally, the material of the separator is selected from one or more of polypropylene, polyethylene, PP / PE / PP composite film, polyvinylidene fluoride, polyacrylonitrile, ceramic separator, ceramic polyamide, aramid, non-woven fabric.

[0018] Optionally, the surface of the separator is provided with a functional wetting agent coating, and the functional wetting agent coating comprises a wetting agent substance, and the wetting agent substance comprises fluoroether and phosphate ester.

[0019] Optionally, the fluoroether comprises one or more of 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether, 1-(2,2,2-trifluoroethoxy)-1,1,2,2-tetrafluoroethane, bis(2,2,2-trifluoroethyl ether), fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether, 1,1,2,2-tetrafluoroethyl ethyl ether, difluoromethyl 2,2,3,3-tetrafluoropropyl ether, ethyl 1,1,2,3,3,3-hexafluoropropyl ether, methyl 2,2,3,3,3-pentafluoropropyl ether.

[0020] Optionally, the phosphate ester comprises one or more of trimethyl phosphate, triethyl phosphate, trimethyl phosphite, dimethyl methylphosphonate, triphenyl phosphate.

[0021] Optionally, the mass ratio of the fluoroether to the phosphate ester is 1-9:9-1.

[0022] The third aspect of the present application provides an electric device comprising the battery as described above.

[0023] According to the electrolyte-separator composite provided in the present application, by introducing the ionic liquid, a large amount of anions are driven into Li + solvated sheath, and the solvated structure can be regulated by a series of weak interactions. In the case of fluorinated anion-dominated solvated structure, multiple regulation of the interface can be completed, which can effectively regulate the solvated structure of Li + and the derived interface, and further match the surface-coated wetting agent functional separator. In the process of battery operation, the wetting agent is gradually released into the electrolyte, which can effectively improve the wettability of the ionic liquid to the separator and the pole piece. Not only can the use temperature of the battery be widened, the long cycle life of the battery be improved, the energy density and power density of the battery be improved, but also the safety of the battery can be improved. DETAILED DESCRIPTION

[0024] In order to make the technical problems, technical solutions and beneficial effects solved by the present application clearer, the present application will be further described in detail below in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0025] The test methods used in the following embodiments are conventional methods unless otherwise specified; the materials, reagents, etc. used are reagents and materials available from commercial channels unless otherwise specified.

[0026] The first aspect of the present application provides an electrolyte comprising an organic solvent, a lithium salt and an additive, wherein the organic solvent comprises an ionic liquid, the ionic liquid comprises a cation and an anion, the cation comprises one or more of a pyrrolidine cation, an imidazole cation, a piperidine cation, and a pyridine cation having a group represented by Structural Formula I-V:

[0027] wherein R1-R10 in Structural Formula I-V are each independently one or more of C1-C8 alkyl, C1-C8 alkyl isomers;

[0028] The anion comprises one or more of a bistrifluoromethanesulfonylimide, a bifluoromethanesulfonylimide, a hexafluorophosphate, a tetrafluoroborate, and a carbonyl-containing anion having a group represented by Structural Formula VI-X:

[0029] In a preferred embodiment, the ionic liquid comprises a mixture of one or more cations and one or more anions.

[0030] Specifically, the electrolyte system of the present application is applied to a battery with a high cut-off voltage (> 4.3V). The introduction of the ionic liquid of the present application not only drives a large number of anions into the Li + The solvation sheath can also be regulated by a series of weak interactions. In the case of fluorinated anion-dominated solvation structure, the multiple regulation of the interface can effectively regulate the solvation structure of Li + The solvation structure and derived interface of Li can not only widen the use temperature of the battery, improve the long cycle life of the battery, improve the energy density and power density of the battery, but also improve the safety of the battery.

[0031] In an embodiment, the percentage content of the ionic liquid in the total mass of the electrolyte is 2%-95%, based on 100% of the total mass of the electrolyte.

[0032] In a preferred embodiment, the percentage content of the ionic liquid in the total mass of the electrolyte is 20-60%; specifically, the percentage content of the ionic liquid in the total mass of the electrolyte is any one value or a range value consisting of any two point values selected from the group consisting of 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, and 95%.

[0033] In an embodiment, the organic solvent includes an ether solvent, and the ether solvent includes one or more of 2-dimethoxyethane, ethylene glycol dimethyl ether, dimethoxydimethyl ether, diethylene glycol dimethyl ether, 1,3-dioxolane, triethylene glycol monoethyl ether, tetrahydrofuran, and 2-methyl-tetrahydrofuran.

[0034] Specifically, the ether solvent has the characteristic of low viscosity, which can effectively reduce the viscosity of the ionic liquid and improve the conductivity of the electrolyte. Moreover, the wettability of the electrolyte to the electrode sheet and the separator can be effectively improved, and the fast-charging performance of the ionic liquid electrolyte can be improved.

[0035] The present application has good flame retardant properties by combining ionic liquid with linear ether solvent. The mixed solvent system generates stable SEI and CEI through solvation structure regulation, provides a stable cycle basis for the battery system under high voltage conditions, and improves the safety characteristics of the battery.

[0036] By optimizing the proportion of the ionic liquid with high-pressure resistance and flame retardant properties and the low-viscosity ether solvent, the solvation structure of Li+ can be effectively adjusted, an SEI film is generated on the negative electrode surface, and a uniform and dense interface layer (CEI) is formed on the positive electrode side, thereby inhibiting side reactions and structural damage to the high-voltage positive electrode, effectively improving the high-voltage cycle stability and safety of the battery; and the problem of high-voltage failure of the traditional carbonate electrolyte is solved.

[0037] In an embodiment, the percentage content of the ether solvent in the total mass of the electrolyte is 2% to 95%.

[0038] In a preferred embodiment, the percentage content of the ether solvent in the total mass of the electrolyte is 20% to 60%; specifically, the percentage content of the ether solvent in the total mass of the electrolyte is any one value or a range value consisting of any two point values selected from the group consisting of 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, and 95%.

[0039] By optimizing the proportion of the ionic liquid and the ether solvent, the solvation structure of Li + is effectively adjusted, and the introduction of the ionic liquid not only drives a large number of anions into the Li + solvation sheath, but also regulates the solvation structure through a series of weak interactions, and in the case of fluorinated anion-dominated solvation structure, the multiple regulation of the interface is completed.

[0040] In an embodiment, the lithium salt includes one or more of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium trifluoromethylsulfonate, lithium bis(trifluoromethylsulfonyl)imide, lithium bisfluorosulfonylimide, lithium trifluoromethylsulfonyl-N-perfluorobutylsulfonylimide, lithium fluorosulfonyl-N-perfluorobutylsulfonylimide, lithium bisoxalate borate, lithium difluorooxalate borate, lithium difluorophosphate, and lithium nitrate.

[0041] The lithium salt is the source of Li + in the electrolyte, provides free-shuttle ions for the battery, and bears the role of transporting ions inside the battery, and the lithium salt can also form a protective layer on the surface of the electrode material, which has an important influence on the capacity, cycle performance, power density, energy density, and other performances of the battery.

[0042] In an embodiment, the lithium salt accounts for 1-60% of the total mass of the electrolyte.

[0043] In a preferred embodiment, the lithium salt accounts for 10-50% of the total mass of the electrolyte; specifically, the lithium salt accounts for 1%, 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, or 60%, or a range formed by any two of the above values, of the total mass of the electrolyte.

[0044] In an embodiment, the additive includes one or more of fluoroethylene carbonate, 1,3-propane sultone, vinylene carbonate, vinyl sulfate, lithium nitrate, lithium borate, lithium difluoro(oxalato)borate.

[0045] The fluoroethylene carbonate (FEC) additive can enhance the stability of the electrode material; the 1,3-propane sultone (1,3-PS) can inhibit the occurrence of side reactions on the electrode surface and the dissolution of metal ions, improve the initial capacity of the battery, improve the high and low temperature storage performance of the battery, increase the cycle number of the battery, and prolong the service life; the vinylene carbonate (VC) can form a solid electrolyte interface film (SEI film) on the negative electrode surface during the initial charge and discharge of the battery. The vinyl sulfate can inhibit the decrease of the initial capacity of the battery, increase the initial discharge capacity, reduce the expansion of the battery after high-temperature storage, and improve the charge and discharge performance and cycle number of the battery.

[0046] In an embodiment, the additive accounts for 0.1-20% of the total mass of the electrolyte.

[0047] In a preferred embodiment, the additive accounts for 2-10% of the total mass of the electrolyte; specifically, the additive accounts for 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%, or a range formed by any two of the above values, of the total mass of the electrolyte.

[0048] In a preferred embodiment, monomers and initiators are added to the electrolyte, and the electrolyte is cured by heating to form a gel electrolyte.

[0049] Specifically, the monomer includes one or more of an olefin monomer containing a sulfonic acid group, an acrylamide monomer, and an acrylic ester monomer; specifically, the olefin monomer containing a sulfonic acid group includes one or more of 2-acrylamido-2-methylpropane sulfonic acid sodium, 2-acrylamido dodecyl sulfonic acid sodium, dodecyl sulfonic acid sodium, and 2-acrylamido octyl sulfonic acid sodium; specifically, the acrylamide monomer includes one or more of acrylamide, methacrylamide, isopropyl acrylamide, N,N-diethyl acrylamide, isobutoxy methyl acrylamide, and diacetone acrylamide; and specifically, the acrylic ester monomer includes one or more of butyl acrylate, methyl acrylate, ethyl acrylate, 2-methyl methacrylate, and isooctyl acrylate.

[0050] Specifically, the initiator includes one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2,4,6(trimethylbenzoyl) diphenyl phosphine oxide, 2,4,6-trimethylbenzoyl phosphinic acid ethyl ester, methyl o-benzoylbenzoate, benzophenone, 4-phenyl benzophenone, and 4-dimethylamino-benzoic acid ethyl ester; preferably, the lithium salt is selected from one or more of lithium bistrifluoromethylsulfonimide, lithium perchlorate, lithium tetrafluoroborate, lithium dioxalate borate, lithium difluorophosphate, lithium hexafluorophosphate, lithium bisfluorosulfonylimide, lithium difluorooxalate borate, and lithium hexafluoroarsenate.

[0051] In an embodiment, the electrolyte accounts for 80%-90% of the total mass of the gel electrolyte; the monomer accounts for 10-18% of the total mass of the gel electrolyte; and the initiator accounts for 0.01%-0.1% of the total mass of the gel electrolyte.

[0052] In a preferred embodiment, the electrolyte accounts for 82%-88% of the total mass of the gel electrolyte; specifically, the electrolyte accounts for any one value or a range value consisting of any two point values selected from 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, and 90% of the total mass of the gel electrolyte.

[0053] In a preferred embodiment, the monomer accounts for 12%-16% of the total mass of the gel electrolyte; specifically, the monomer accounts for any one value or a range value consisting of any two point values selected from 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, and 18% of the total mass of the gel electrolyte.

[0054] In a preferred embodiment, the initiator is present in the gel electrolyte in a percentage of 0.02% to 0.08% of the total mass of the gel electrolyte; in particular, the electrolyte is present in the gel electrolyte in a percentage of 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%, or a range between any two of the values.

[0055] Further, in an embodiment, the electrolyte is added to the solid-state electrolyte to form a semi-solid-state electrolyte.

[0056] In particular, the solid-state electrolyte comprises an inorganic solid-state electrolyte, a polymer solid-state electrolyte, and a composite solid-state electrolyte, the inorganic solid-state electrolyte comprises one or more of an oxide solid-state electrolyte, a sulfide solid-state electrolyte, and a halide solid-state electrolyte; the polymer solid-state electrolyte comprises a polymer matrix selected from one or more of polyethylene oxide, polyvinylidene fluoride, and polyvinylidene fluoride-hexafluoropropylene copolymer; the composite solid-state electrolyte comprises an inorganic filler and a polymer matrix, the inorganic filler is selected from at least one of an inert filler and an active filler, the inert filler is one or more of silicon dioxide, titanium dioxide, aluminum oxide, metal organic frameworks (MOFs), and zeolites; the active filler is one or more of cubic garnet lithium lanthanum zirconium oxide (LLZO), lithium lanthanum zirconium tantalum oxide (LLZTO), NASICON-type lithium aluminum titanium phosphate (LATP), perovskite lithium lanthanum titanium oxide, sulfide electrolyte, and halide electrolyte; the polymer matrix comprises one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene and derivatives thereof, polyacrylonitrile, polymethyl methacrylate, or polyethyl methacrylate and derivatives thereof.

[0057] In an embodiment, the electrolyte is present in the solid-state electrolyte in a percentage of 0.5% to 50% of the total mass of the solid-state electrolyte.

[0058] In a preferred embodiment, the electrolyte accounts for 10-40% of the total mass of the solid-state electrolyte; specifically, the electrolyte accounts for 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, or 50% of the total mass of the gel electrolyte, or a range value consisting of any two of the above-mentioned values.

[0059] The second aspect of the present application provides a battery comprising a positive electrode sheet, a negative electrode sheet, a separator, and the electrolyte as described above.

[0060] In some embodiments, the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer coated on one or both sides of the positive electrode current collector, the positive electrode active material layer comprising a positive electrode active material, a conductive agent, and a binder.

[0061] In an embodiment, the positive electrode sheet comprises a positive electrode active material selected from one or more of lithium cobalt phosphate (LFP), lithium manganese iron phosphate (LMFP), lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium nickel oxide (LNO), ternary material (NCM, NCA), lithium-rich manganese-based (LMR), lithium nickel manganese oxide (LNMO), lithium vanadium phosphate oxide (Li3V2(PO4)3, LiVOPO4).

[0062] In some embodiments, the positive electrode conductive agent comprises one or more of graphite, superconducting carbon, acetylene black, carbon black, carbon nanotubes, graphene, carbon nanofibers, metal powder, metal fibers, and polyphenylene derivatives.

[0063] In some embodiments, the positive electrode binder comprises one or more of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylic ester resin.

[0064] In some embodiments, the mass percentage of each component in the positive electrode active material layer is: 96-98wt% of positive electrode active material, 0.5-2wt% of conductive agent, and 1.0-2.0wt% of binder.

[0065] The mass percentage of the positive active material in the positive active material layer is within the above range, which can make the positive electrode sheet have a higher lithium extraction and insertion capacity, and make the battery have a higher capacity.

[0066] The positive current collector is selected from metal materials that can conduct electrons, preferably, the positive current collector comprises one or more of copper, nickel, tin, copper, stainless steel, in a more preferred embodiment, the positive current collector is selected from aluminum foil.

[0067] The positive electrode sheet can be prepared according to conventional methods in the art. For example, the positive active material layer is generally prepared by coating a positive electrode slurry comprising positive active material, positive conductive agent, positive binder and any other components on the positive current collector, and then dried and cold-pressed. The solvent can be N-methyl pyrrolidone (NMP), but is not limited thereto.

[0068] In some embodiments, the negative electrode sheet comprises a negative current collector and a negative active material layer coated on one or both sides of the negative current collector, the negative active material layer comprising negative active material, conductive agent, binder and thickening agent.

[0069] In an embodiment, the negative electrode sheet comprises a negative active material selected from one or more of graphite negative electrode, silicon-oxygen negative electrode, silicon-carbon negative electrode, silicon negative electrode, tin negative electrode, tin oxide negative electrode, tin alloy negative electrode (Sn-Fe, Sn-Co, Sn-Cu, etc.), lithium metal negative electrode, lithium alloy negative electrode (Li-Ag, Li-Al, Li-Sn, Li-Mg, Li-Zn, Li-In, Li-Ga, etc.) or lithium-free negative electrode.

[0070] In some embodiments, the negative conductive agent comprises one or more of graphite, superconducting carbon, acetylene black, carbon black, carbon nanotubes, graphene, carbon nanofibers, metal powder, metal fiber and polyphenylene derivative.

[0071] In some embodiments, the negative binder comprises one or more of butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol and polymethacrylic acid.

[0072] In some embodiments, the thickening agent comprises one or more of sodium alginate, sodium carboxymethyl cellulose and carboxymethyl chitosan.

[0073] In some embodiments, the mass percentage of each component in the negative active material layer is: 96%-97% of negative active material, 0.5%-1.5% of conductive agent, 1%-2% of binder and 0.5%-1.5% of thickening agent.

[0074] The mass ratio of the negative active material and the mesoporous material in the negative electrode film layer is within the above range, which can enable the mesoporous material and the active material to be in sufficient contact, enable the electrolyte stored in the mesoporous material to be directly delivered to the active material, and enable lithium to reach the interface of the active material more quickly through the mesoporous material, thereby improving the kinetics and cycle performance.

[0075] The negative current collector is selected from metal materials capable of conducting electrons, preferably, the negative current collector comprises one or more of Al, Ni, tin, copper and stainless steel, and in a more preferred embodiment, the negative current collector is selected from a copper foil.

[0076] The negative electrode sheet can be prepared according to conventional methods in the art. For example, the negative active material layer is generally prepared by coating a negative active material, a negative conductive agent, a negative binder and any other components on a negative current collector to form a negative electrode slurry, and then drying and cold-pressing. The solvent can be a water-based solvent, but is not limited thereto.

[0077] In an embodiment, the material of the separator is selected from one or more of polypropylene, polyethylene, a PP / PE / PP composite film, polyvinylidene fluoride, polyacrylonitrile, a ceramic separator, a ceramic polyamide, aramid and non-woven fabric.

[0078] In an embodiment, the surface of the separator is provided with a functional wetting agent coating, and the functional wetting agent coating comprises a wetting agent substance, and the wetting agent substance comprises a fluorine ether and a phosphate ester.

[0079] By mixing the fluorine ether and the phosphate ester to form a functional wetting agent, coating the functional wetting agent on the surface of the separator to form a functional wetting agent coating, and gradually releasing the substances with wetting effect in the functional wetting agent coating into the electrolyte during the cycle of the battery, the wettability of the electrolyte to the electrode sheet and the separator can be effectively improved, the fast-charging performance of the battery under room temperature conditions can be effectively improved, and the battery system has excellent cycle stability under high cut-off voltage.

[0080] In addition, the battery of the present application can be matched with different high-voltage cathodes, and the composite electrolyte system is used in combination with the separator with the functional wetting agent coating, which can provide good wettability for the electrode sheet of the battery, effectively improve the rate performance of the battery under room temperature conditions, and provide a basis for stable cycle of the battery.

[0081] In an embodiment, the fluoroether includes one or more of 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether, 1-(2,2,2-trifluoroethoxy)-1,1,2,2-tetrafluoroethane, bis(2,2,2-trifluoroethyl ether), fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether, 1,1,2,2-tetrafluoroethyl ethyl ether, difluoromethyl 2,2,3,3-tetrafluoropropyl ether, ethyl 1,1,2,3,3,3-hexafluoropropyl ether, methyl 2,2,3,3,3-pentafluoropropyl ether.

[0082] In an embodiment, the phosphate ester includes one or more of trimethyl phosphate, triethyl phosphate, trimethyl phosphite, dimethyl methylphosphonate, triphenyl phosphate.

[0083] In an embodiment, the mass ratio of the fluoroether to the phosphate ester is 1-9:9-1.

[0084] In a preferred embodiment, the mass ratio of the fluoroether to the phosphate ester is 7-9:3-1; specifically, the mass ratio of the fluoroether to the phosphate ester is any one of 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, or 9:1 or a range value consisting of any two of the above ratios.

[0085] By optimizing the ratio of the ionic liquid to the low-viscosity linear ether solvent, the viscosity of the electrolyte is significantly reduced, the ionic conductivity of the electrolyte is improved, and by matching the specific ratio of the fluoroether and the phosphate ester composite coating separator, the substances with wetting effect on the surface of the separator are gradually released into the electrolyte during the battery cycle process, which can effectively improve the wettability of the electrolyte to the electrode and the separator, and can effectively improve the fast charging performance of the battery under room temperature conditions, so that the battery system has excellent cycle stability under high cut-off voltage.

[0086] In a preferred embodiment, the preparation of the battery includes the following steps:

[0087] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, with the separator between the positive and negative electrodes to play a separating role. The electrode sheet and the separator are placed in the aluminum plastic film bag shaped by the punching shell, and the electrolyte, the gel electrolyte, or the solid-state electrolyte prepared above is injected into the baked and dried battery cell, and the battery is obtained after vacuum packaging, standing, and formation processes.

[0088] The third aspect of the present application provides a power utilization device including the battery according to the above-mentioned battery.

[0089] The third aspect of the present application provides a power utilization device including the battery according to the second aspect of the present application. The battery serves as the power source of the device. The number of batteries in the power utilization device can be adjusted according to the application and capacity of the power utilization device.

[0090] Preferably, the electric device can be, but is not limited to, an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc.

[0091] The advantages of the present application are further illustrated in the following examples.

[0092] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application is described in further detail in the following examples. However, it should be understood that the examples of the present application are only for the purpose of explanation of the present application, and are not intended to limit the present application, and the examples of the present application are not limited to the examples given in the specification. The specific experimental conditions or operation conditions not mentioned in the examples are made according to the conventional conditions or the conditions recommended by the material suppliers.

[0093] In addition, it should be understood that the one or more method steps mentioned in the present application do not exclude that there can be other method steps before and after the combination steps or other method steps can be inserted between the explicitly mentioned steps, unless otherwise stated; it should also be understood that the combination connection relationship between the one or more devices / apparatuses mentioned in the present application does not exclude that there can be other devices / apparatuses before and after the combination devices / apparatuses or other devices / apparatuses can be inserted between the two explicitly mentioned devices / apparatuses, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the arrangement order of each method step or to limit the scope of the present application, and the change or adjustment of the relative relationship, without substantially changing the technical content, is also regarded as the scope of the present application that can be implemented.

[0094] In the following examples, the reagents, materials and instruments used are commercially available or obtained by the synthesis methods known in the art, unless otherwise specified.

[0095] Table 1 Design of electrolyte of Examples 1-11 and Comparative Examples 1-4;

[0096] Example 1

[0097] This example is used to illustrate the electrolyte and battery disclosed in the present application; including the following operation steps:

[0098] Preparation of electrolyte: in an argon-filled glove box (O2<1 ppm, H2O<1 ppm), ion liquid 1-methyl-1-propyl pyrrolidinium bisfluorosulfonylimide (MPPyFSI), ether solvent ethylene glycol dimethyl ether (DME) were mixed in a mass ratio of 5.5:0.9, and after stirring uniformly, a mixed solvent was obtained, 35wt% lithium salt LiFSI was slowly added to the mixed solvent, and finally 1wt% fluoroethylene carbonate (FEC) was added to obtain the electrolyte.

[0099] Preparation of positive electrode sheet: the positive electrode active material lithium nickel cobalt manganese oxide (NCM), the conductive agent CNT, and the binder PVDF were mixed in a mass ratio of 97:1.5:1.5. The mixture was stirred in NMP solvent to form a uniform positive electrode slurry. The slurry was coated on at least one side of the positive electrode current collector aluminum foil, and after drying, rolling, die cutting and other processes, the required positive electrode sheet was obtained.

[0100] The negative electrode is a lithium metal negative electrode.

[0101] Preparation of separator: a PE porous polymer film was used as the separator substrate.

[0102] Bis(2,2,2-trifluoroethyl ether) (BTFE) and triethyl phosphate (TEP) were mixed in a mass ratio of 2:3 to obtain a wetting agent mixture, which was coated on both sides of the PE porous polymer film. After drying, die cutting and other processes, the required separator was obtained.

[0103] Preparation of battery:

[0104] The positive electrode sheet, the separator and the negative electrode sheet were stacked in order, with the separator between the positive and negative electrodes to play a separating role. Then the stacked electrode sheet and separator were placed in an aluminum-plastic film bag shaped by a punch shell. The non-aqueous electrolyte prepared above was injected into the oven-dried battery cell. After vacuum packaging, standing and formation, a 1Ah battery was obtained.

[0105] Examples 2-8

[0106] Examples 2-8 are used to illustrate the electrolyte and battery disclosed in the present application, including most of the operation steps in Example 1, the difference being that:

[0107] The components and contents of the organic solvents in the electrolyte shown in Table 1, and the components and contents of the wetting agent in the separator.

[0108] Comparative Examples 1-4

[0109] Comparative Examples 1-4 are used to illustrate the electrolyte and battery disclosed in the present application, including most of the operation steps in Example 1, the difference being that:

[0110] The components and contents of the organic solvent in the electrolyte shown in Table 1, and the components and contents of the wetting agent in the separator.

[0111] Performance test

[0112] The batteries prepared in Examples 1-11 and Comparative Examples 1-4 were subjected to the following performance tests:

[0113] (1) Electrolyte oxidation potential test: The electrolyte separator was subjected to oxidation potential test by linear sweep potential method, EC-Lab electrochemical workstation, test voltage range was 2.5-6V, scan rate was 1mV·s -1 , the method used "stainless steel sheet | separator | lithium sheet" device structure for test, with stainless steel sheet as working electrode, lithium sheet as reference electrode.

[0114] (2) Electrolyte separator composite system conductivity test: The ionic conductivity of the electrolyte separator was determined by electrochemical impedance spectroscopy (EIS), the battery was assembled into a structure of "stainless steel sheet | separator | stainless steel sheet", and the EC-Lab electrochemical workstation was used for test, the frequency range was 100kHz to 10mHz, the oscillation voltage was 5mV, the test temperature was 25±3℃, and the ionic conductivity was calculated by the following formula: σ = l / RA

[0115] l is the thickness of the electrolyte separator (cm), R is the impedance value of the electrolyte separator measured by EIS (Ω), and A is the effective contact area between the stainless steel sheet and the electrolyte separator (cm 2 ).

[0116] (3) Cell cycle performance test: 0.5C / 0.5D cycle charge-discharge test was carried out at a voltage range of 3.0V-4.3V and a temperature of 25℃, and the capacity retention rate of the battery after 100 cycles was recorded.

[0117] The test results are shown in Table 2.

[0118] Table 2 Test results of Examples 1-11 and Comparative Examples 1-4

[0119] As can be seen from Table 2, the introduction of a functional coating with wetting effect on the surface in the ionic liquid and ether solvent composite electrolyte system not only improves the wettability of the ionic liquid-based electrolyte to the separator, but also effectively regulates the solvation structure of the electrolyte system during the operation of the battery, improves its oxidation stability and improves the cycle stability of the battery system.

[0120] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An electrolyte, wherein: comprising an organic solvent, a lithium salt, and an additive, the organic solvent comprising an ionic liquid, the ionic liquid comprising a cation and an anion, the cation comprising one or more of the following structural formulas: In the structural formula I-structural formula V, R1-R10 are each independently one or more of C1-C8 alkyl, C1-C8 alkyl isomers; The anion comprises one or more of the following structural formulae:

2. The electrolyte of claim 1, wherein: The percentage content of the ionic liquid in the total mass of the electrolyte is 2%-95%.

3. The electrolyte of claim 1, wherein: The organic solvent includes an ether solvent, and the ether solvent includes one or more of 2-dimethoxyethane, ethylene glycol dimethyl ether, dimethoxy dimethyl ether, diethylene glycol dimethyl ether, 1,3-dioxolane, triethylene glycol monoethyl ether, tetrahydrofuran, and 2-methyl-tetrahydrofuran.

4. The electrolyte of claim 3, wherein: The percentage content of the ether solvent in the total mass of the electrolyte is 2%-95%.

5. The electrolyte of claim 1, wherein: The lithium salt includes one or more of lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium trifluoromethylsulfonate, lithium bis(trifluoromethylsulfonyl)imide, lithium bisfluorosulfonylimide, lithium trifluoromethylsulfonyl-n-perfluorobutylsulfonylimide, lithium fluorosulfonyl-n-perfluorobutylsulfonylimide, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium difluorophosphate, and lithium nitrate.

6. The electrolyte of claim 1 or 5, wherein: The percentage content of the lithium salt in the total mass of the electrolyte is 1%-60%.

7. The electrolyte of claim 1, wherein: The additive includes one or more of fluoroethylene carbonate, 1,3-propane sultone, vinylene carbonate, ethylene sulfate, lithium nitrate, lithium borate, and lithium difluoro(oxalato)borate.

8. The electrolyte of claim 1 or 7, wherein: The percentage content of the additive in the total mass of the electrolyte is 0.1%-20%.

9. A battery, wherein: The battery includes a positive electrode sheet, a negative electrode sheet, a separator, and the electrolyte as claimed in any one of claims 1-8.

10. The battery of claim 9, wherein: The material of the separator is selected from one or more of polypropylene, polyethylene, a PP / PE / PP composite film, polyvinylidene fluoride, polyacrylonitrile, a ceramic separator, a ceramic polyamide, aramid, and non-woven fabric.

11. The battery of claim 9, wherein: A functional wetting agent coating is arranged on the surface of the separator, and the functional wetting agent coating includes a wetting agent substance, and the wetting agent substance includes fluoroether and phosphate ester.

12. The battery of claim 11, wherein: The fluoroether includes one or more of 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether, 1-(2,2,2-trifluoroethoxy)-1,1,2,2-tetrafluoroethane, bis(2,2,2-trifluoroethyl ether), fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether, 1,1,2,2-tetrafluoroethyl ethyl ether, difluoromethyl 2,2,3,3-tetrafluoropropyl ether, ethyl 1,1,2,3,3,3-hexafluoropropyl ether, and methyl 2,2,3,3,3-pentafluoropropyl ether.

13. The battery of claim 11, wherein: The phosphate ester includes one or more of trimethyl phosphate, triethyl phosphate, trimethyl phosphite, dimethyl methylphosphonate, and triphenyl phosphate.

14. The battery of claim 11, wherein: The mass ratio of the fluoroether to the phosphate ester is 1-9:9-1.

15. An electrical device, comprising: The battery includes the battery as claimed in any one of claims 9-14.

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