Fluorine-containing alcohol-based diluent electrolyte and application thereof

Abstract

The invention is applicable to the technical field of electrochemical energy storage, and provides a fluorine-containing alcohol-based diluent electrolyte and application thereof, the fluorine-containing alcohol-based diluent electrolyte comprises a solvent, a zinc salt and a fluorine-containing alcohol-based diluent, and the fluorine-containing alcohol-based diluent accounts for 10-90 vol% of the total volume of the electrolyte; the fluorine-containing alcohol-based diluent is at least one of a straight-chain fluoroalcohol compound and a derivative thereof, a branched-chain fluoroalcohol compound and a derivative thereof, and a naphthenic fluoroalcohol compound and a derivative thereof, and the fluorine-containing alcohol-based diluent has a hydrophilic hydroxyl group and a hydrophobic fluorine-containing carbon chain, and is induced to form a water-rich and water-poor interlaced three-dimensional microphase separation structure in the electrolyte; zinc ions are mainly located in a water-rich phase and keep water solvation, anions tend to be distributed in a water-poor phase, and the ion decoupling type local high-concentration electrolyte is formed. Zinc ions get rid of polyanion coordination clusters, migration resistance is reduced, ion mobility and conductivity are improved, hydrogen evolution side reactions are inhibited, zinc dendrites and corrosion are relieved, interface stability is remarkably improved, and the cycle life is prolonged.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage technology, and particularly relates to an electrolyte containing a fluorinated alcohol-based diluent and its application. Background Technology

[0002] Aqueous batteries based on zinc metal anodes offer advantages such as low cost and intrinsically high safety. Zinc is abundant and possesses a high theoretical specific capacity (820 mAh g⁻¹). -1 ) and volumetric capacity (5854 mAh cm⁻¹) -3 However, the shortcomings of traditional aqueous electrolytes have limited their commercialization: water has a narrow electrochemical stability window (<2.0 V), which severely restricts the application of high-voltage cathodes and the improvement of energy density. The core problem is that a large amount of "free water" is highly active and easily induces hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at the electrode interface, leading to electrolyte consumption and battery swelling. At the same time, water molecules erode the negative electrode, causing corrosion and disordered dendrite growth, eventually piercing the separator and causing a short circuit, resulting in challenges such as short cycle life and reduced safety of the battery.

[0003] Currently, existing technologies often incorporate low-carbon chain alcohols (such as methanol and ethanol) as co-solvents to reduce water activity. However, these solvents have significant drawbacks: firstly, their high volatility makes it difficult to meet the stability requirements of electrolyte components in long-cycle batteries; secondly, low-carbon alcohols, due to their high CH bond activity, have weak antioxidant capacity and are easily decomposed at high potentials, making them unsuitable for high-voltage cathode materials. Furthermore, common alcohols cannot induce the formation of a dense and hydrophobic solid electrolyte interphase (SEI) film on the zinc anode surface, failing to fundamentally solve the problems of dendrite growth and interfacial corrosion. Therefore, it is necessary to develop an electrolyte diluent system that can both suppress zinc dendrites and withstand high voltages while maintaining low volatility. Summary of the Invention

[0004] The purpose of this invention is to provide an electrolyte containing a fluorinated alcohol-based diluent, thereby addressing the problems mentioned in the background art.

[0005] Unlike traditional low-proportion additive systems, this invention uses a higher proportion of fluorinated alcohol-based diluents, which, in addition to their dilution effect, also induce the formation of a three-dimensional local microphase separation structure with interwoven water-rich and water-poor phases under macroscopic homogeneous conditions of the electrolyte, thanks to the amphiphilicity of their hydrophilic hydroxyl groups and hydrophobic fluorinated carbon chains. The hydroxyl groups of the fluorinated alcohol diluent are preferentially distributed in the water-rich phase or its interface, while the fluorinated carbon chains are preferentially distributed in the water-poor phase. Zinc ions are mainly located in the water-rich phase and maintain a solvation environment dominated by water molecules. Due to the strong interaction with the fluorinated alcohol diluent, anions tend to be distributed in the water-poor phase, thereby achieving spatial decoupling of zinc ions and anions. Furthermore, zinc ions primarily migrate in the aqueous phase, avoiding the excessively large solvation clusters formed when multiple anions co-enter the first solvation shell in traditional high-concentration electrolytes. This reduces migration units and migration resistance, thereby improving zinc ion mobility and ionic conductivity. Therefore, this invention does not rely on high salinity to form a conventional high-concentration electrolyte, but rather improves the transport hysteresis problem of high-concentration electrolytes by suppressing active water side reactions through local microphase separation and ion decoupling.

[0006] The present invention is implemented as follows: an electrolyte containing a fluorinated alcohol-based diluent comprises a solvent, a zinc salt, and a fluorinated alcohol-based diluent, wherein the concentration of the zinc salt in the electrolyte is 0.5-10 mol / L, and the volume of the fluorinated alcohol-based diluent accounts for 10-90 vol% of the total volume of the electrolyte. The fluorinated alcohol diluent is at least one of straight-chain fluorinated alcohols and their derivatives, branched-chain fluorinated alcohols and their derivatives, and cycloalkyl fluorinated alcohols and their derivatives. The structures of the straight-chain fluorool compounds and their derivatives are shown below: X-(CH m F 2-m ) n -CH2-OH; Where n is an integer representing the number of carbon atoms in the main chain excluding the terminal hydroxymethyl group, satisfying the total number of carbons 4≤(n+1)≤8; m and 2-m are both positive integers less than or equal to 2; X is the chain-terminal group; The structures of the branched alkyl fluorool compounds and their derivatives are shown below: R1-C(R2)(R3)-(CH2) m -OH; Where m is 0 or 1; when m=1, at least one of R2 and R3 is a C1-C3 alkyl or fluoroalkyl side chain; when m=0, R2 is a C1-C4 alkyl or fluoroalkyl, in which case the hydroxyl group is directly attached to the branching point or non-terminal carbon; R1 is a straight-chain or branched C1-C6 fluoroalkyl; when R3 is not a side chain, it is a hydrogen atom; The structures of the cycloalkylfluorool compounds and their derivatives are shown below: Cyclo(R F )-OH; Among them, Cyclo(R F ) represents a C5-C7 cycloalkyl skeleton partially substituted with fluorine atoms.

[0007] Another objective of this invention is to provide an application of an electrolyte containing a fluorinated alcohol-based diluent in the preparation of energy storage devices.

[0008] Compared with the prior art, the present invention has at least the following beneficial effects: 1. By increasing the volume fraction of fluorinated alcohol-based diluents in the electrolyte, fluorinated alcohols are transformed from ordinary additives into key components that dominate the evolution of microstructure; 2. Because fluorinated alcohol molecules possess both hydrophilic hydroxyl groups and hydrophobic fluorinated carbon chains, they can construct a three-dimensional local microphase separation structure with interwoven water-rich and water-poor phases under macroscopic homogeneous conditions; 3. This local microphase separation structure is conducive to achieving spatial decoupling of zinc ions and anions, so that zinc ions are mainly located in the water-rich phase, while anions tend to be located in the water-poor phase relative to zinc ions; 4. Unlike traditional high-concentration electrolytes where zinc ions are coordinated by multiple anions to form excessively large solvated clusters, this invention frees zinc ions from unfavorable multi-anion coordinated clusters, which is beneficial to improving zinc ion mobility and overall ionic conductivity. 5. By reducing the adverse participation of active water at the zinc anode interface and regulating the anion decomposition and film formation process at the interface, hydrogen evolution side reaction, zinc corrosion and dendrite growth can be effectively suppressed, thereby improving cycle stability. Attached Figure Description

[0009] Figure 1 The electrochemical performance comparison results of the half-cells prepared with the electrolytes of Example 1 and Comparative Example 1 of this invention are shown. Figure 2 The results show a comparison of the electrochemical performance of the half-cells prepared with the electrolytes of Example 2 and Comparative Example 2 of this invention. Figure 3 The electrochemical performance of full cells prepared with the electrolytes of Examples 1-4 and Comparative Examples 1-2 of this invention is shown. Detailed Implementation

[0010] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0011] This invention provides an electrolyte comprising a fluorohydrin-based diluent, wherein the fluorohydrin-based diluent is at least one of a straight-chain fluorohydrin compound and its derivatives, a branched-chain fluorohydrin compound and its derivatives, or a cycloalkyl fluorohydrin compound and its derivatives. Fluorohydric diluents have the following general structure: R-OH; Wherein, R is selected from fluorinated C4-C8 straight-chain alkyl, fluorinated C4-C8 branched alkyl, or fluorinated C4-C8 cycloalkyl; the hydrogen atoms in the fluorinated alkyl are partially or completely replaced by fluorine atoms. R represents a hydrophobic organic group that is partially or completely replaced by fluorine, with a total number of carbon atoms (C) ranging from 4 to 8. Based on the differences in the microstructure of the R group, the embodiments of the present invention further subdivide fluorohydric diluents into the following three categories, each possessing the following unique structural characteristics: (1) Straight-chain alkyl fluorohydrin compounds and their derivatives: These types of diluents are characterized by their linearly arranged fluorinated carbon chains without side chain branches. This linear structure endows the molecules with low viscosity and good wettability, and they have the following general structure: X-(CH m F 2-m ) n -CH2-OH; Where n is an integer representing the number of carbon atoms in the main chain excluding the terminal hydroxymethyl group, satisfying the total number of carbons 4≤(n+1)≤8; m and 2-m are both positive integers less than or equal to 2, that is, m can be 0, 1, or 2, representing the number of hydrogen atoms (H) or fluorine atoms (F) in the repeating carbon chain unit; X is the chain-end group, selected from hydrogen atoms (H), fluorine atoms (F), or other functional groups; Specifically, it can be at least one of the following compounds: 4,4,4-trifluorobutanol, 2,2,3,4,4,4-hexafluoro-1-butanol, 2,2,3,3,4,4,5,5-octafluoro-1-pentanol, 3,3,4,4,5,5,6,6,6-nonafluoro-1-hexanol, 2,2,3,3,4,4,5,5,6,6,6-undecanofluoro-1-hexanol, 1,1,7-trihydro-dodecanofluoro-1-heptanol, and 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecanofluoro-1-octanol.

[0012] (2) Branched alkyl fluorohydrin compounds and their derivatives: These diluents are characterized by the presence of alkyl or fluoroalkyl side chains (branchings) on their carbon chain backbone. The steric hindrance effect generated by the branches can effectively regulate the local microenvironment, while reducing the crystallization tendency of the solvent and improving low-temperature performance. They have the following general structure: R1-C(R2)(R3)-(CH2) m -OH; Where m takes the value 0 or 1; when m=1 (i.e., primary alcohol), at least one of R2 and R3 is a C1-C3 alkyl or fluoroalkyl side chain; when m=0 (i.e., secondary or tertiary alcohol), R2 is a C1-C4 alkyl or fluoroalkyl, in which case the hydroxyl group is directly attached to the branching point or non-terminal carbon; R1 is a straight-chain or branched fluoroalkyl (C1-C6); when R3 is not a side chain, it is selected from hydrogen atoms (H); Specifically, it may be at least one of the following specific compounds: the branched alkyl fluorool compound and its derivatives are at least one of 1,1,1,3,3,3-hexafluoro-2-(trifluoromethyl)prop-2-ol, 4,4,4-trifluoro-2-methylbut-1-ol, 3,3,4,4,4-pentafluoro-2-butanol, 3,3,4,4,5,5,5-heptafluoropent-2-ol, and 2-amino-4,4,4-trifluoro-2-methylbut-1-ol.

[0013] (3) Cycloalkyl fluorohydrides: These diluents are characterized by the introduction of cyclic structures into their carbon skeleton. The cycloalkyl skeleton provides strong rigid support, which enhances the thermal stability of the diluent molecules and restricts excessive free rotation of the molecules at the interface, resulting in the following general structure: Cyclo(R F )-OH; Among them, Cyclo(R F ) represents a C5-C7 cycloalkyl skeleton partially substituted with fluorine atoms; Specifically, it can be at least one of the following compounds: 2-fluorocyclopentanol, 2,2-difluorocyclopentanol, 3,3-difluorocyclopentanol, 2-fluorocyclohexanol, 2,2-difluorocyclohexanol, 3,3-difluorocyclohexanol, 4,4-difluorocyclohexanol, and 4,4-difluorocycloheptanol.

[0014] In some embodiments of the present invention, the volume of the fluorohydrin diluent accounts for 10-90 vol% of the total electrolyte volume, based on the total electrolyte volume. In some embodiments of the present invention, the volume of the fluorohydrin diluent, based on the total volume of the electrolyte, is 10 vol%, 15 vol%, 20 vol%, 25 vol%, 30 vol%, 35 vol%, 40 vol%, 45 vol%, 50 vol%, 55 vol%, 60 vol%, 65 vol%, 70 vol%, 75 vol%, 80 vol%, 85 vol%, 90 vol%, or any range thereof.

[0015] In some embodiments of the present invention, the electrolyte further includes deionized water or a mixture of deionized water and non-aqueous organic solvents; In some embodiments of the present invention, the non-aqueous organic solvent is selected from at least one of alcohols, ethers, carbonates, phosphates, nitriles, sulfones, amides, and siloxanes. In some embodiments of the present invention, the non-aqueous organic solvent is at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, ethylene glycol dimethyl ether, tetrahydrofuran, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, diphenyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, dimethyl carbonate, methyl acetate, methyl propionate, ethyl acetate, ethyl propionate, propyl acetate, propyl propionate, ethylene carbonate, propylene carbonate, butenyl carbonate, γ-butyrolactone, butylene carbonate, trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, dimethyl methylphosphonate, acetonitrile, sulfolane, methyl ethyl sulfone, dimethylformamide, dimethylacetamide, dimethyldimethoxysilane, methyltriethoxysilane, tetraethyl orthosilicate, dimethyldiethoxysilane, methyltrimethoxysilane, and dimethyldimethoxysilane. In some embodiments of the present invention, the volume of non-aqueous organic solvent accounts for 0-95 vol% of the total electrolyte volume, based on the total volume of the electrolyte.

[0016] In some embodiments of the present invention, the electrolyte further includes a zinc salt, which is at least one of an inorganic zinc salt and an organic zinc salt; In some embodiments of the present invention, the zinc salt is at least one of zinc sulfate (ZnSO4), zinc chloride (ZnCl2), zinc bromide (ZnBr2), zinc iodide (ZnI2), zinc trifluoromethanesulfonate (Zn(OTf)2), zinc acetate (Zn(CH3COO)2), zinc nitrate (Zn(NO3)2), zinc perchlorate (Zn(ClO4)2), zinc tetrafluoroborate (Zn(BF4)2), and zinc bis(trifluoromethanesulfonyl)imide (Zn(TFSI)2). More preferably, the zinc salt is zinc trifluoromethanesulfonate (Zn(OTf)2), zinc acetate (Zn(CH3COO)2), or zinc bis(trifluoromethanesulfonyl)imide (Zn(TFSI)2). In some embodiments of the present invention, the concentration of zinc salt in the electrolyte is 0.5 mol / L, 1.0 mol / L, 1.5 mol / L, 2.0 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, 5 mol / L, 5.5 mol / L, 6 mol / L, 6.5 mol / L, 7 mol / L, 7.5 mol / L, 8 mol / L, 8.5 mol / L, 9 mol / L, 9.5 mol / L, 10 mol / L, or any range thereof. In some embodiments of the present invention, the zinc salt content accounts for 13-52 wt% of the total mass of the electrolyte, based on the total mass of the electrolyte.

[0017] This invention also provides a secondary battery, such as a zinc secondary battery, including zinc metal secondary batteries, zinc ion secondary batteries, zinc polymer secondary batteries, zinc-based flow batteries, and zinc-air batteries; In some embodiments of the present invention, the secondary battery of this application includes a positive electrode, a negative electrode, a separator and / or a solid electrolyte and an electrolyte solution; This secondary battery can be applied to energy storage power stations, uninterruptible power supplies, large household batteries, portable outdoor energy storage power supplies, flexible wearable electronic devices, implantable medical electronic devices, rail transit braking energy recovery devices, substation DC operating power supplies, laptops, input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, headsets, video recorders, LCD TVs, portable cleaners, portable CD players, mini CDs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, electric bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, and other fields. The electrolyte used in this secondary battery is the electrolyte described above. In addition, it may also contain other electrolytes that do not depart from the scope of the present invention. In some embodiments of the present invention, the negative electrode sheet includes a negative current collector and a negative electrode material layer. The negative electrode material layer is disposed on the surface of the negative current collector and includes a negative electrode active material. The specific type of negative electrode active material is not specifically limited and can be selected according to requirements. In some embodiments of the present invention, the negative electrode active material is at least one of silicon-based materials, carbon-based materials, tin-based materials, phosphorus-based materials, metallic zinc, or zinc alloys. The silicon-based material is at least one of silicon, silicon alloys, silicon oxides, and silicon-carbon compounds. The carbon-based material is at least one of graphite, soft carbon, hard carbon, carbon nanotubes, and graphene. The tin-based material is at least one of tin, tin oxides, and tin alloys. The phosphorus-based material is phosphorus and / or phosphorus complexes. In some embodiments of the present invention, the negative electrode material layer further includes a binder for improving the bonding between the negative electrode active material particles and the bonding between the negative electrode active material and the current collector. Based on the total mass of the negative electrode material layer, the mass of the binder accounts for 0.3-5% of the total mass of the negative electrode material layer. In some embodiments of the present invention, non-limiting examples of binders include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc. In some embodiments of the present invention, the negative electrode material layer may further include a conductive agent, wherein the mass of the conductive agent accounts for 0.3-3% of the total mass of the negative electrode material layer based on the total mass of the negative electrode material layer. The conductive agent may include any conductive material, as long as it does not cause a chemical change. Non-limiting examples of conductive materials include carbon-based materials (e.g., natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, etc.), metal-based materials (e.g., metal powder, metal fiber, etc., such as copper, nickel, aluminum, silver, etc.), conductive polymers (e.g., polyphenylene derivatives), and mixtures thereof. In some embodiments of the present invention, the negative electrode current collector may be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymer substrate coated with conductive metal, and combinations thereof; In some embodiments of the present invention, the zinc negative electrode is zinc metal or zinc alloy, and can be in the form of foil or powder. In some embodiments of the present invention, the zinc alloy comprises zinc and a metal / quasi-metal that can be alloyed with zinc, such as Si, Sn, Al, Ge, Pb, Bi, Sb, Si-Y alloy (where Y is an alkali metal, alkaline earth metal, Group 13-16 element, transition metal, rare earth element or a combination thereof, other than Si), or Sn-Y alloy (where Y is an alkali metal, alkaline earth metal, Group 13-16 element, transition metal, rare earth element or a combination thereof, other than Sn). Y can be Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, or combinations thereof; In some embodiments of the present invention, the positive electrode sheet involved includes a current collector and a positive electrode active material layer located on the current collector; in some embodiments of the present invention, the selection of the positive electrode active material includes, but is not limited to: manganese dioxide (MnO2), manganese trioxide (Mn2O3), manganese trioxide (Mn3O4), spinel lithium manganese oxide (LiMn2O4), lithium-rich manganese-based solid solution (xLi2MnO3·(1-x)LiMO2), zinc manganate (ZnMn2O4), sodium manganate (Na2O4). 0.44 MnO2), magnesium manganese oxide (MgMn2O4), vanadium pentoxide (V2O5), vanadium dioxide (VO2), lithium vanadate (LiV3O8), sodium vanadate (NaV3O8), zinc vanadate hydrate (ZnO2), etc. 0.25 V₂O₅·nH₂O, ammonium vanadate (NH₄V₄O) 10 Calcium vanadate (CaV6O) 16• 3H2O, hydrated vanadium pentoxide (V2O5·nH2O), ferric ferricyanide (Prussian blue) (Fe4[Fe(CN)6]3), copper hexacyanoferrate (K2Cu[Fe(CN)6]), zinc hexacyanoferrate (K2Zn3[Fe(CN)6]2), sodium vanadium phosphate (Na3V2(PO4)3), polyaniline (PANI), polypyrrole (PPy), polythiophene derivative (PEDOT), p-benzoquinone (C6H4O2), pyrene-4,5,9,10-tetraone (C 16 H6O4), iodine (I2), lead dioxide (PbO2), nickel hydroxyl oxide (NiOOH), silver oxide (Ag2O), molybdenum disulfide (MoS2), molybdenum diselenide (MoSe2); In some embodiments of the present invention, the positive electrode active material layer further includes an adhesive for improving the bonding between the positive electrode active material particles and the bonding between the positive electrode active material and the current collector, and optionally includes a conductive material; in some embodiments of the present invention, the adhesive is selected from at least one of polyvinyl alcohol, polyacrylic acid, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyacrylamide, polymethyl methacrylate, sodium alginate, chitosan, gelatin, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin or nylon, etc. In some embodiments of the present invention, the selection of conductive materials includes, but is not limited to: carbon-based materials, metal-based materials, conductive polymers, and mixtures thereof; in some embodiments of the present invention, the carbon-based materials are selected from natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or any combination thereof; in some embodiments of the present invention, the metal-based materials are selected from metal powder, metal fiber, copper, nickel, aluminum, or silver; in some embodiments of the present invention, the conductive polymer is a polyphenylene derivative. In this embodiment of the invention, the material and shape of the diaphragm are not particularly limited, and can be any technology disclosed in the prior art. For example, the diaphragm may include a substrate layer and a surface treatment layer. The substrate layer may be a glass fiber filter membrane, bacterial cellulose membrane, nonwoven fabric, membrane, or composite membrane with a porous structure. The material of the substrate layer is at least one of glass fiber, cellulose, polyethylene, polypropylene, and polyethylene terephthalate. Specifically, a glass fiber filter membrane, bacterial cellulose membrane, polypropylene nonwoven fabric, polyethylene nonwoven fabric, or polypropylene-polyethylene-polypropylene porous composite membrane may be selected. At least one surface of the substrate layer is provided with a surface treatment layer, which may be a polymer layer or an inorganic layer, or a layer formed by mixing polymers and inorganic substances. The inorganic layer includes inorganic particles and a binder, and the inorganic particles are alumina, silicon oxide, magnesium oxide, oxygen, etc. The material contains at least one of titanium dioxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, and barium sulfate; and the binder is at least one of polyvinyl alcohol, polyacrylic acid, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyacrylamide, polymethyl methacrylate, sodium alginate, chitosan, gelatin, polyvinylidene fluoride, a copolymer of polyvinylidene fluoride and hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl alkoxy, polymethyl methacrylate, polytetrafluoroethylene, and polyhexafluoropropylene. In some embodiments of the present invention, the diaphragm is a glass fiber diaphragm, wherein the diaphragm thickness is in the range of 0.7 to 2.7 mm, and the air permeability is 3.7-19 s·100 mL·in. 2 Within the range; In some embodiments of the present invention, the secondary battery may include an outer packaging, which may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.; the outer packaging of the secondary battery may also be a soft pack, such as a pouch-type soft pack, and the material of the soft pack may be plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), etc.

[0018] This invention also provides a device including the aforementioned secondary battery. This device includes, but is not limited to, energy storage systems, energy storage systems, electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, etc. In order to meet the high power and high energy density requirements of the secondary battery for this device, a battery pack or battery module can be used.

[0019] Unless otherwise specified, all reagents, materials and instruments used in the following examples and comparative examples are commercially available.

[0020] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0021] Example 1: An electrolyte containing a fluorinated alcohol-based diluent, the preparation method of which includes the following steps: Dissolve 363.53 mg Zn(OTf)2 in 0.6 mL of water, then add 0.6 mL of 4,4,4-trifluorobutanol for dilution, and stir to obtain the electrolyte.

[0022] Example 2: An electrolyte containing a fluorinated alcohol-based diluent, the preparation method of which includes the following steps: 363.53 mg Zn(OTf)2 was dissolved in 0.6 mL of water, and then diluted with 0.6 mL of 2,2,3,3,4,4,5,5-hexafluoro-1-butanol. The electrolyte was obtained after stirring.

[0023] Example 3: An electrolyte containing a fluorinated alcohol-based diluent, the preparation method of which includes the following steps: Dissolve 363.53 mg Zn(OTf)2 in 0.6 mL of water, then add 0.2 mL of methanol, and then add 0.4 mL of 1,1,1,3,3,3-hexafluoro-2-(trifluoromethyl)prop-2-ol for dilution. After stirring, the electrolyte is obtained.

[0024] Example 4: An electrolyte containing a fluorinated alcohol-based diluent, the preparation method of which includes the following steps: Dissolve 363.53 mg Zn(OTf)2 in 0.6 mL of water, then add 0.2 mL of methanol, and then add 0.4 mL of 2-fluorocyclopentanol for dilution. After stirring, the electrolyte is obtained.

[0025] Example 5: An electrolyte containing a fluorinated alcohol-based diluent, the preparation method of which includes the following steps: Dissolve 363.53 mg Zn(OTf)2 in 0.6 mL of water, then add 0.2 mL of methanol, and then add 0.4 mL of 2-amino-4,4,4-trifluoro-2-methylbut-1-ol for dilution. After stirring, the electrolyte is obtained.

[0026] Comparative Example 1: An electrolyte, the preparation method of which includes the following steps: 363.53 mg Zn(OTf)2 was dissolved in 1.2 mL of water and stirred to obtain an electrolyte.

[0027] Comparative Example 2: An electrolyte, the preparation method of which includes the following steps: 363.53 mg Zn(OTf)2 was dissolved in 0.6 mL of water and stirred to obtain an electrolyte.

[0028] Comparative Example 3: An electrolyte, the preparation method of which includes the following steps: 363.53 mg Zn(OTf)2 was dissolved in 0.3 mL of water, and then 0.9 mL of 4,4,4-trifluorobutanol was added and stirred to obtain a heterogeneous liquid in which the zinc salt was not dissolved.

[0029] Comparative Example 4: An electrolyte, the preparation method of which includes the following steps: 363.53 mg Zn(OTf)2 was dissolved in 0.6 mL of water, and then 0.2 mL of methanol was added. After stirring, an electrolyte was obtained.

[0030] Comparative Example 5: An electrolyte, the preparation method of which includes the following steps: Dissolve 90.88 mg Zn(OTf)2 in 0.6 mL of water, then add 0.2 mL of methanol and stir to obtain the electrolyte.

[0031] Zn / Cu batteries were manufactured using the electrolytes from Examples 1-5 and Comparative Examples 1-5 according to Table 1, and then coulombic efficiency and cycle stability tests were performed. The coulomb efficiency test process is as follows: Zn / Cu batteries are used for testing. The batteries are assembled in the following order: negative electrode shell, spring plate, gasket, zinc plate, separator, copper plate, and positive electrode shell. 50-90 microliters of electrolyte are added to each battery to wet the separator, and finally, the battery is sealed. The batteries are first tested at a voltage range of 0-1V with a flow rate of 0.1 mA / cm². 2 The current density was pre-charged and discharged 5 times at 1 mA / cm². 2 The zinc was stripped at a current density until the voltage exceeded 1V, and then the battery was subjected to a current density of 1 mA / cm² in the 0-1V voltage range. 2 Deposition was performed at a current density of 1 mA / cm for one hour, followed by deposition at 1 mA / cm. 2 The current density was used to strip zinc until the voltage exceeded 1V, and the coulombic efficiency was calculated: Coulomb efficiency = Discharge capacity / Charge capacity; Full cell capacity retention test: Zn / V2O5 batteries were used for testing. The batteries were assembled in the following order: negative electrode shell, spring contact, gasket, zinc plate, separator, positive electrode plate, and positive electrode shell. 50 to 90 microliters of electrolyte were added to each battery to wet the separator, and finally, the batteries were sealed. The batteries were first pre-charged and discharged at a current density of 0.1C within the 0.3-1.5V voltage range, followed by charge-discharge cycles at a current density of 1C within the 0.3-1.5V voltage range. The results are as follows Figure 1 , Figure 2 As shown in Tables 1, 2, and 3: Table 1

[0032] Table 2

[0033] Table 3

[0034] As can be seen, compared with the traditional low-concentration electrolyte (1M Zn(OTf)2) of Comparative Example 1, the high-concentration electrolyte (zinc salt > 2M) of Comparative Example 2, and the ordinary water / organic solvent blend electrolyte of Comparative Example 4, the locally high-concentration electrolyte system diluted with fluorinated alcohols showed stable zinc metal cycle coulombic efficiency and long life, which can effectively improve the cycle life of zinc metal / zinc ion batteries. This indicates that in the absence of effective control, the high activity of water molecules leads to severe hydrogen evolution reaction and disordered growth of zinc dendrites, which eventually punctures the separator and causes battery failure. In contrast, Examples 1-5, which introduced fluorinated alcohols, showed improved cycle life. The lifespan has generally increased to over 500 cycles, and the first-efficiency has generally increased to the range of 85-91%. These results indicate that the electrolyte provided in this embodiment of the invention does not simply rely on high salinity, low content of additives, or common co-solvents to improve cycle performance. Instead, it induces the formation of a three-dimensional local microphase separation structure with interwoven water-rich and water-poor phases under macroscopic homogeneous conditions through a high proportion of fluorinated alcohol-based diluents. This constructs an ion-decoupled local high-concentration electrolyte system, which significantly improves interface stability and cycle reversibility while suppressing hydrogen evolution, side reactions, and dendrite growth. Further comparison of Examples 1 and 2 with Examples 3-5 shows that branched-chain fluorinated alcohols and cycloalkyl fluorinated alcohols are generally superior to straight-chain fluorinated alcohols. Specifically, Example 3, using a branched-chain fluorinated alcohol, achieved a cycle life of 1036 cycles, and Example 4, using a cycloalkyl fluorinated alcohol, achieved a cycle life of 920 cycles, both higher than Examples 1 and 2 corresponding to straight-chain fluorinated alcohols. Meanwhile, Table 3 shows that the capacity retention rates of Examples 3 and 4 after 100 cycles were 89.6% and 90.2%, respectively, significantly better than the 67.8% of Example 1 and higher than the 86.7% of Example 2. These results indicate that, compared to straight-chain fluorinated alcohols, branched and cyclic structures are more conducive to controlling the local microenvironment and interfacial solvation structure of the electrolyte, thereby further improving long-cycle stability and capacity retention while ensuring high reversible deposition / stripping. The comparison between Examples 1-5 and Comparative Example 4 also shows that although the common organic co-solvent methanol can improve cycling performance to some extent, its effect is significantly weaker than that of the fluorinated alcohol-based diluent system. This is because methanol only acts as a general co-solvent and cannot simultaneously achieve local microphase organization, anion enrichment regulation, and interfacial film stabilization. In contrast, the fluorinated alcohol-based diluent used in the embodiments of this invention possesses both hydrophilic hydroxyl groups and hydrophobic fluorinated carbon chains, enabling it to exert an amphiphilic interfacial regulation effect in the electrolyte. This allows zinc ions to preferentially migrate in the water-rich phase, while anions tend to associate with the fluorinated alcohol-based diluent and distribute in the water-poor phase, thus achieving spatial decoupling of zinc ions and anions. This ion decoupling effect helps reduce the probability of multiple anions entering the first solvation shell of zinc ions in traditional high-concentration electrolytes, avoiding the formation of excessively large solvation clusters, reducing zinc ion migration units and migration resistance, and thus improving the zinc ion transport number and effective ion transport capacity. The above mechanism is consistent with the high coulombic efficiency, excellent rate / capacity retention characteristics, and long-life cycling results exhibited by the system of this invention. The comparison between Example 1 and Comparative Example 3 further illustrates that the amount of fluorinated alcohol-based diluent is not necessarily better the higher it is. When the proportion of fluorinated alcohol is too high and the water content in the system is insufficient, the solubility of zinc salt decreases, the system cannot maintain macroscopic homogeneity, and eventually a heterogeneous liquid is formed, causing the battery to fail to cycle normally. Therefore, this invention emphasizes the construction of an ion-decoupled local high-concentration electrolyte with "macroscopic homogeneity-microscopic phase separation" within a specific composition window, rather than simply increasing the content of fluorinated alcohol. Furthermore, the comparison between Examples 3-5 and Comparative Example 5 shows that if the zinc salt concentration is too low, even with the introduction of organic components, it is difficult to form a stable and effective local high-concentration structure, and the battery cycle life is still significantly limited. This indicates that the superior performance of the present invention comes from the synergistic matching of the proportion of fluorinated alcohol-based diluent, the zinc salt concentration, and the microphase separation structure. Among them, branched fluorinated alcohols and cycloalkyl fluorinated alcohols show more prominent advantages in constructing stable microphase structures, promoting ion decoupling, and improving zinc ion transport.

[0035] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An electrolyte containing a fluorinated alcohol-based diluent, characterized in that, The electrolyte comprises a solvent, a zinc salt, and a fluorinated alcohol-based diluent, wherein the volume of the fluorinated alcohol-based diluent accounts for 10-90 vol% of the total electrolyte volume; the electrolyte is macroscopically homogeneous and microscopically forms a three-dimensional local microphase separation structure with interwoven water-rich and water-poor phases; the hydroxyl groups of the fluorinated alcohol-based diluent are distributed in the water-rich phase or at the water-rich phase interface, and the fluorinated carbon chains are distributed in the water-poor phase, exhibiting amphiphilic interface regulation characteristics.

2. The electrolyte of the fluorinated alcohol-based diluent according to claim 1, characterized in that, The fluorinated alcohol diluent is at least one of straight-chain fluorinated alcohols and their derivatives, branched-chain fluorinated alcohols and their derivatives, and cycloalkyl fluorinated alcohols and their derivatives. The structures of the straight-chain fluorool compounds and their derivatives are shown below: X-(CH m F 2-m ) n -CH2-OH; Where n is an integer representing the number of carbon atoms in the main chain excluding the terminal hydroxymethyl group, satisfying the total number of carbons 4≤(n+1)≤8; m and 2-m are both positive integers less than or equal to 2; X is the chain-terminal group; The structures of the branched alkyl fluorool compounds and their derivatives are shown below: R1-C(R2)(R3)-(CH2) m -OH; Where m is 0 or 1; when m=1, at least one of R2 and R3 is a C1-C3 alkyl or fluoroalkyl side chain; when m=0, R2 is a C1-C4 alkyl or fluoroalkyl, in which case the hydroxyl group is directly attached to the branching point or non-terminal carbon; R1 is a straight-chain or branched C1-C6 fluoroalkyl; when R3 is not a side chain, it is a hydrogen atom; The structures of the cycloalkylfluorool compounds and their derivatives are shown below: Cyclo(R F )-OH; Among them, Cyclo(R F ) represents a C5-C7 cycloalkyl skeleton partially substituted with fluorine atoms.

3. The electrolyte of the fluorinated alcohol-based diluent according to claim 2, characterized in that, The straight-chain fluorools and their derivatives are at least one of the following: 4,4,4-trifluorobutanol, 2,2,3,4,4,4-hexafluoro-1-butanol, 2,2,3,3,4,4,5,5-octafluoro-1-pentanol, 3,3,4,4,5,5,6,6,6-nonafluoro-1-hexanol, 2,2,3,3,4,4,5,5,6,6,6-undecanofluoro-1-hexanol, 1,1,7-trihydro-dodecanofluoro-1-heptanol, and 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecanofluoro-1-octanol. The branched alkyl fluorools and their derivatives are at least one of 1,1,1,3,3,3-hexafluoro-2-(trifluoromethyl)prop-2-ol, 4,4,4-trifluoro-2-methylbut-1-ol, 3,3,4,4,4-pentafluoro-2-butanol, 3,3,4,4,5,5,5-heptafluoropentanol, and 2-amino-4,4,4-trifluoro-2-methylbut-1-ol; The cycloalkyl fluorinated alcohol compound and its derivatives are at least one selected from 2-fluorocyclopentanol, 2,2-difluorocyclopentanol, 3,3-difluorocyclopentanol, 2-fluorocyclohexanol, 2,2-difluorocyclohexanol, 3,3-difluorocyclohexanol, 4,4-difluorocyclohexanol, and 4,4-difluorocycloheptanol.

4. The electrolyte of the fluorinated alcohol-based diluent according to any one of claims 1 to 3, characterized in that, Based on the total volume of the electrolyte, the volume fraction of the fluorinated alcohol-based diluent is 10 vol% to 90 vol%, preferably 35 vol% to 60 vol%.

5. The electrolyte of the fluorinated alcohol-based diluent according to any one of claims 1 to 3, characterized in that, The zinc salt is at least one of zinc sulfate, zinc chloride, zinc bromide, zinc iodide, zinc trifluoromethanesulfonate, zinc acetate, zinc nitrate, zinc perchlorate, zinc tetrafluoroborate, and zinc bis(trifluoromethanesulfonyl)imide.

6. The electrolyte of the fluorinated alcohol-based diluent according to any one of claims 1 to 3, characterized in that, The concentration of the zinc salt in the electrolyte is 1-3 mol / L.

7. The electrolyte of the fluorinated alcohol-based diluent according to any one of claims 1 to 3, characterized in that, The solvent is deionized water, or a mixture of deionized water and a non-aqueous organic solvent; The non-aqueous organic solvent is selected from at least one of alcohols, ethers, carbonates, phosphates, nitriles, sulfones, amides, and siloxanes. The volume of the non-aqueous organic solvent accounts for 0-95 vol% of the total electrolyte volume.

8. The application of an electrolyte containing a fluorinated alcohol-based diluent as described in any one of claims 1 to 3 in the preparation of energy storage devices.

9. The energy storage device according to claim 8, wherein the energy storage device is one of a zinc-ion battery, a zinc metal battery, a zinc-ion hybrid capacitor, and a zinc-air battery.

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