Fluoro-sulfinate compound, preparation method and non-aqueous electrolyte

Abstract

The invention provides a fluorinated sulfinate compound, a preparation method and a non-aqueous electrolyte. The structural formula of the fluorinated sulfinate compound is shown as a structural formula I, and R is selected from C1-C6 fluoroalkyl. The fluoro-sulfinate compound comprises a fluorine-containing group substituted alcohol and a fluorine-containing sulfinyl skeleton, has the advantages of both the fluorine-containing group substituted alcohol and the fluorine-containing sulfinyl, can form a good protective film on the interface of positive and negative electrode materials, has relatively low internal resistance, can be used as an additive to improve the rate and low-temperature performance of a battery, and can be applied to the field of lithium ion batteries, such as lithium ion batteries, lithium ion batteries, lithium ion batteries, lithium ion batteries, lithium ion batteries, lithium ion batteries, lithium ion batteries, lithium ion batteries, lithium ion batteries and lithium ion batteries. Good application prospects are realized.

Description

Technical Field

[0001] This invention belongs to the field of new energy battery technology, and particularly relates to a fluorosulfinic acid ester compound and its preparation method, as well as a non-aqueous electrolyte. Background Technology

[0002] Electrolyte is the lifeblood of lithium-ion batteries, playing a crucial role in transferring lithium ions between the positive and negative electrode materials and the separator. Furthermore, the electrolyte significantly influences the formation of the SEI and CEI at the interface between the positive and negative electrode materials, as well as their impedance. With the rapid development of pure electric vehicles and hybrid electric vehicles, the requirements for energy density, long cycle life, rate performance, and safety of lithium-ion batteries are constantly increasing. The positive electrode material for lithium-ion batteries has shifted from lithium iron phosphate and lithium manganese oxide systems to ternary material systems. In traditional electrolyte systems, ternary cathode materials undergo significant interfacial catalytic reactions under high voltage and high temperature conditions, leading to electrolyte decomposition and gas production, which compromises battery life and safety.

[0003] Currently, studies have reported that adding additives that can form films at the interface of ternary cathode materials (such as organic additives VC, PS, DTD, TMSP; and inorganic additives LiPO2F2, LiFSI, LiTFSI, LiPF2(C2O4)2, LiBOB, etc.) to the electrolyte can effectively protect the cathode, improve the electrolyte's withstand voltage window, and increase the battery's cycle life. However, studies have also found that these additives can form not only a CEI film at the cathode material interface but also an SEI film at the graphite anode interface, leading to increased internal resistance and affecting the battery's rate capability and low-temperature performance. Therefore, it is necessary to develop new additives to address the shortcomings of currently available commercial electrolyte additives. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a fluorosulfinic acid ester compound, its preparation method, and a non-aqueous electrolyte. This fluorosulfinic acid ester compound possesses a unique functional group structure and can be used as an additive in non-aqueous electrolytes to improve battery rate capability and low-temperature performance.

[0005] To achieve the above objectives, the first aspect of the present invention provides a fluorosulfinic acid ester compound with the structural formula shown in structural formula I, wherein R is selected from C1 to C6 fluoroalkyl groups.

[0006]

[0007] This fluorosulfinic acid ester compound comprises a fluorinated alcohol and a fluorinated sulfinyl skeleton, combining the advantages of both. It can form a good protective film at the interface of positive and negative electrode materials and has low internal resistance. It can be used as an additive to improve the rate and low-temperature performance of batteries and has good application prospects.

[0008] As one technical solution of the present invention, R is selected from C1 to C6 polyfluoroalkyl groups.

[0009] As a technical solution of the present invention, at least one of compounds one to six is ​​selected.

[0010]

[0011]

[0012] A second aspect of this invention provides a method for preparing fluorosulfinic acid esters, comprising the steps of: (1) A first solution is formed by mixing the compound as shown in structural formula II, an organic base, and a first solvent at room temperature; (2) The compound shown in structural formula III is mixed with a second solvent to form a second solution. The second solution is added dropwise to the first solution at a certain temperature to carry out the reaction and obtain the product. The product is then purified and dried.

[0013]

[0014] The preparation method of this invention uses a compound as shown in structural formula II to modify trifluoromethylsulfinyl chloride as shown in structural formula III, synthesizing a series of fluorosulfinic acid esters with novel structures. This preparation method utilizes readily available raw materials, is simple in process, has high yield, high purity, good atom economy, and is easy to industrialize. The obtained fluorosulfinic acid esters can effectively improve the low-temperature and rate performance of batteries.

[0015] As a technical solution of the present invention, the first solvent and the second solvent are each independently selected from at least one of nitrile solvents, halogenated hydrocarbon solvents, ether solvents, ester solvents, ketone solvents and aromatic hydrocarbon solvents.

[0016] As a technical solution of the present invention, the first solvent and the second solvent are each independently selected from at least one of acetonitrile, butyronitrile, n-hexane, cyclohexane, dichloromethane, trichloromethane, 1,2-dichloroethane, tetrachloroethane, methyl tert-butyl ether, ethylene glycol dimethyl ether, tetrahydrofuran, dioxane, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl acetate, ethyl acetate, propyl acetate, acetone, cyclohexanone, 4-methyl-2-pentanone, benzene, xylene, and toluene.

[0017] As one technical solution of the present invention, the certain temperature is -10~30℃, the dropping time is 10~60min, and the reaction time is 1~24h.

[0018] As a technical solution of the present invention, the molar ratio of the compound shown in structural formula II to the compound shown in structural formula III is 1.0~2.5:1.0. As a technical solution of the present invention, the organic base is selected from at least one of pyridine, triethylamine, imidazole, 4-dimethylaminopyridine and tetramethylguanidine, and the molar ratio of the compound as shown in structural formula II to the organic base is 1.0:1.0~3.0.

[0019] As one technical solution of the present invention, the purification includes filtration and / or washing, the drying temperature is 35~120℃, and the drying time is 1~24h.

[0020] A third aspect of the present invention provides a non-aqueous electrolyte comprising an electrolyte salt, a non-aqueous organic solvent, and an additive, wherein the additive comprises the aforementioned fluorosulfinic acid ester compounds.

[0021] The non-aqueous electrolyte of this invention uses fluorosulfinic acid esters as additives, as shown in structural formula I. Fluorine-substituted alcohols have strong electron-withdrawing capabilities. These strongly electron-withdrawing fluorine-containing groups (fluorinated substituted alcohols, fluorinated sulfinyl groups) stabilize the compound's structure and induce preferential reduction / oxidation reactions on the surfaces of the positive and negative electrode materials, forming a uniform, dense, and low-resistance solid electrolyte interphase (SEI) film or positive electrode electrolyte interphase (CEI) film. The low-resistance interfacial film reduces charge transport resistance, ensuring rapid lithium-ion insertion / extraction during high-rate charge / discharge, and reducing obstacles to lithium-ion migration at low temperatures, thereby improving battery performance under these conditions.

[0022] As one technical solution of the present invention, the fluorosulfinic acid ester compound accounts for 0.1~2.5% of the mass of the non-aqueous electrolyte. Detailed Implementation The fluorosulfinate compounds of this invention can be used as intermediates to synthesize electroplating additives, polycarbonate flame retardants, lubricating grease thickeners, polypropylene antistatic agents, polyethyleneimine crosslinking agents, etc. Furthermore, the fluorosulfinate compounds can be used as electrolyte additives in lithium-ion batteries to improve the low-temperature, rate, and other electrochemical performance of lithium-ion batteries.

[0023] Lithium-ion batteries that use fluorosulfinate compounds as electrolyte additives may include positive electrode active materials, negative electrode active materials, and electrolytes.

[0024] The positive electrode active material can be a layered transition metal lithium oxide or an olivine-type lithium compound. The layered transition metal lithium oxide can be, but is not limited to, lithium cobalt oxides (such as LiCoO2, doped or coated LiCoO2), lithium nickel oxides (such as LiNiO2, doped or coated LiNiO2), lithium manganese oxides (such as LiMnO2, doped or coated LiMnO2, LiMn2O4, doped or coated LiMn2O4), lithium nickel cobalt oxides and their dopants or coatings, lithium manganese cobalt oxides and their dopants or coatings, lithium nickel manganese oxides and their dopants or coatings, and lithium nickel cobalt manganese oxides (with the chemical formula LiNi). x Co y Mn (1-x-y) M z O2, where 0.6≤x<0.9, x+y<1, 0≤z<0.08, and M is at least one of Al, Mg, Zr, and Ti. These positive electrode active materials can be used alone or in combination of two or more. In particular, fluorosulfinates are suitable for lithium nickel cobalt manganese oxide ternary materials.

[0025] The negative electrode active material includes at least one of carbon-based materials, silicon-based materials, and tin-based materials. The carbon-based material may include, but is not limited to, at least one of artificial graphite, natural graphite, hard carbon, soft carbon, graphene, and mesophase carbon microspheres. The silicon-based material may include, but is not limited to, at least one of elemental silicon, silicon-oxygen composite materials, silicon-carbon composite materials, and silicon alloy materials. The tin-based material may include elemental tin, tin-carbon composite materials, tin-oxygen composite materials, and tin alloy compounds.

[0026] Electrolytes consist of electrolyte salts, non-aqueous organic solvents, and additives.

[0027] The electrolyte salt may be, but is not limited to, at least one of lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium methanesulfonate (LiCH3SO3), lithium trifluoromethanesulfonate (LiCF3SO3), lithium dioxalatoborate (C4BLiO8), lithium difluorooxalatoborate (C2BF2LiO4), lithium difluorophosphate (LiPO2F2), and lithium difluorobis(oxalato)phosphate (LiDFBP). The electrolyte salt constitutes 6-15% of the non-aqueous electrolyte by mass. Preferably, the electrolyte salt constitutes 9-15% of the non-aqueous electrolyte by mass. Specifically, the electrolyte salt constitutes 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, and 15% of the non-aqueous electrolyte by mass, but is not limited to these values.

[0028] The non-aqueous organic solvent is selected from carbonates and / or carboxylic acid esters. Further, the non-aqueous organic solvent is selected from at least one of ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), γ-butyrolactone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, ethyl propionate, propyl propionate, and butyl propionate. The non-aqueous organic solvent constitutes 80% or more of the non-aqueous electrolyte by mass, preferably 85% or more. Examples, but not limited to, are 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, and 90%.

[0029] The additive may include at least fluorosulfinates. Further, the structural formula of the fluorosulfinates is shown in Structural Formula I, wherein R is selected from C1-C6 fluoroalkyl groups.

[0030]

[0031] Furthermore, the fluorosulfinate is at least one of compounds one through six.

[0032]

[0033]

[0034] The mass percentage of fluorosulfinates in the non-aqueous electrolyte is 0.1% to 2.5%. For example, the mass percentage of fluorosulfinates may be, but is not limited to, 0.1%, 0.3%, 0.5%, 0.7%, 1.0%, 1.3%, 1.5%, 1.7%, 2.0%, 2.3%, and 2.5%.

[0035] The method for preparing the fluorosulfinic acid ester compounds of the present invention may include the following steps.

[0036] (1) The compound as shown in structural formula II, an organic base, and a first solvent are mixed at room temperature to form a first solution.

[0037] (2) The compound as shown in structural formula III is mixed with a second solvent to form a second solution. The second solution is added dropwise to the first solution at a certain temperature to carry out the reaction and obtain the product. The product is then purified and dried.

[0038] The reaction process of the fluorosulfinic acid ester compounds of the present invention is shown below.

[0039]

[0040] In the compounds represented by structural formula II, R is selected from C1-C6 fluoroalkyl groups. Further, the compounds represented by structural formula II are selected from at least one of 2,2-difluoroethanol, 2,2,2-trifluoroethanol, 2-fluoroethanol, 2,3,3-trifluoroethanol, 2,2,3,3-tetrafluoroethanol, and 2,2,3,3,3-pentafluoroethanol. The fluorosulfinic esters of compounds one through six are synthesized using compounds represented by structural formula II, namely 2,2-difluoroethanol, 2,2,2-trifluoroethanol, 2-fluoroethanol, 2,3,3-trifluoroethanol, 2,2,3,3-tetrafluoroethanol, and 2,2,3,3,3-pentafluoroethanol.

[0041] The organic base is selected from at least one of pyridine, triethylamine, imidazole, 4-dimethylaminopyridine, and tetramethylguanidine. The molar ratio of the compound and the organic base as shown in structural formula II is 1.0:1.0 to 3.0, and by example, but not limited to, 1.0:1.0, 1.0:1.2, 1.0:1.4, 1.0:1.6, 1.0:1.8, 1.0:2.0, 1.0:2.2, 1.0:2.4, 1.0:2.6, 1.0:2.8, and 1.0:3.0.

[0042] The first solvent is selected from at least one of nitrile solvents, halogenated hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, and aromatic hydrocarbon solvents. More specifically, the first solvent is selected from at least one of acetonitrile, butyronitrile, n-hexane, cyclohexane, dichloromethane, trichloromethane, 1,2-dichloroethane, tetrachloroethane, methyl tert-butyl ether, ethylene glycol dimethyl ether, tetrahydrofuran, dioxane, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl acetate, ethyl acetate, propyl acetate, acetone, cyclohexanone, 4-methyl-2-pentanone, benzene, xylene, and toluene.

[0043] In step (1), the first solution needs to be kept at room temperature and stirred for 10 to 60 minutes. For example, the time can be, but is not limited to, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, and 60 minutes.

[0044] In step (2), the second solvent and the first solvent may be the same or different. Further, the second solvent is selected from at least one of nitrile solvents, halogenated hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, and aromatic hydrocarbon solvents. Even further, the second solvent is selected from at least one of acetonitrile, butyronitrile, n-hexane, cyclohexane, dichloromethane, trichloromethane, 1,2-dichloroethane, tetrachloroethane, methyl tert-butyl ether, ethylene glycol dimethyl ether, tetrahydrofuran, dioxane, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl acetate, ethyl acetate, propyl acetate, acetone, cyclohexanone, 4-methyl-2-pentanone, benzene, xylene, and toluene.

[0045] The molar ratio of the compound shown in structural formula II to the compound shown in structural formula III is 1.0 to 2.5:1.0. For example, the molar ratio can be, but is not limited to, 1.0:1.0, 1.2:1.0, 1.5:1.0, 1.7:1.0, 2.0:1.0, 2.3:1.0, or 2.5:1.0. The second solution is added dropwise to the first solution at a controlled temperature to regulate the reaction rate. This controlled temperature is -10 to 30°C, preferably -10 to 10°C. For example, the controlled temperature can be, but is not limited to, -10°C, -5°C, 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, or 30°C. The dropwise addition time is 10 to 60 minutes. For example, the time can be, but is not limited to, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, or 60 minutes. The reaction time is 1 to 24 hours. For example, the reaction time can be, but is not limited to, 1 hour, 3 hours, 5 hours, 7 hours, 9 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours, and 24 hours.

[0046] Purification includes filtration and / or washing. Filtration can be performed using centrifugal stratification, reduced pressure filtration, or ordinary filtration. Washing can be performed multiple times using hydrochloric acid solution, saturated saline solution, or water. Drying can be carried out using forced-air drying at a temperature of 35–120°C. Examples of possible temperatures include, but are not limited to, 35°C, 45°C, 55°C, 65°C, 75°C, 85°C, 95°C, 105°C, 110°C, 115°C, and 120°C. The drying time is 1–24 hours, but is not limited to, 1 hour, 3 hours, 5 hours, 7 hours, 9 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours, and 24 hours.

[0047] To better illustrate the purpose, technical solution, and beneficial effects of this invention, the invention will be further described below with reference to specific embodiments. It should be noted that the methods described below are further explanations of this invention and should not be construed as limiting it.

[0048] Part 1: Preparation of Fluorosulfinates (I) Preparation of Compound 1 (1) Mix 17g of 2,2-difluoroethanol and 100g of dichloromethane evenly at room temperature, and add 17g of pyridine. The pyridine was stirred at room temperature for 10 minutes to form the first solution.

[0049] (2) 30.5 g of trifluoromethyl sulfinyl chloride and 100 g of dichloromethane were mixed evenly to form a second solution. The second solution was added dropwise to the first solution at 0 °C for 1 h and reacted for 8 h to obtain the product. The product was filtered, and the filtrate was extracted with water, separated, dried over anhydrous magnesium sulfate, concentrated and distilled, and then vacuum dried at 50 °C for 10 h to obtain 35.2 g of compound one. The yield of compound one was 89.4%, and the purity was 99%. Compound one was tested, and its... 1 H NMR (400MHz, CDCl3, ppm): d 5.30(tt,1H), 3.89(dt,2H).

[0050] (II) Preparation of Compound II (1) Mix 21g of 2,2,2-trifluoroethanol and 120g of dichloromethane at room temperature until homogeneous, add 17g of pyridine and stir at room temperature for 10min to form the first solution.

[0051] (2) 30.5 g of trifluoromethyl sulfinyl chloride and 100 g of dichloromethane were mixed evenly to form a second solution. The second solution was added dropwise to the first solution at 0 °C for 1 h and reacted for 8 h to obtain the product. The product was filtered, and the filtrate was extracted with water, separated, dried over anhydrous magnesium sulfate, concentrated and distilled, and then vacuum dried at 50 °C for 10 h to obtain 39.3 g of compound II. The yield of compound II was 91.2%, and the purity was 99%. Compound II was tested, and its... 1 H NMR (400MHz, CDCl3, ppm): δ4.5 (dd, 2H).

[0052] (IIII) Preparation of Compound Three (1) Mix 14g of 2-fluoroethanol and 100g of dichloromethane at room temperature until homogeneous, add 17g of pyridine and stir at room temperature for 10min to form the first solution.

[0053] (2) 30.5 g of trifluoromethyl sulfinyl chloride and 100 g of dichloromethane were mixed evenly to form a second solution. The second solution was added dropwise to the first solution at 0 °C for 1 h and reacted for 8 h to obtain the product. The product was filtered, and the filtrate was extracted with water, separated, dried over anhydrous magnesium sulfate, concentrated and distilled, and then vacuum dried at 50 °C for 10 h to obtain 29.5 g of compound 3. The yield of compound 3 was 82.1%, and the purity was 99%. Compound 3 was tested, and its... 1 H NMR (400MHz, CDCl3, ppm): δ4.28(dt,2H), 3.73(dt,2H).

[0054] (IV) Preparation of Compound Four (1) Mix 24g of 2,3,3-trifluoroethanol and 120g of dichloromethane at room temperature until homogeneous, add 17g of pyridine and stir at room temperature for 10min to form the first solution.

[0055] (2) 30.5 g of trifluoromethyl sulfinyl chloride and 100 g of dichloromethane were mixed evenly to form a second solution. The second solution was added dropwise to the first solution at 0 °C for 1 h and reacted for 8 h to obtain the product. The product was filtered, and the filtrate was extracted with water, separated, dried over anhydrous magnesium sulfate, concentrated and distilled, and then vacuum dried at 50 °C for 10 h to obtain 43.2 g of compound IV. The yield of compound IV was 94.1%, and the purity was 99%. Compound IV was tested, and its... 1 H NMR (400MHz, CDCl3, ppm): δ 5.76 (tq, 1H), 5.12-4.61 (m,, 1H), 3.87-3.43 (m, 2H).

[0056] (V) Preparation of Compound Five (1) Mix 27g of 2,2,3,3-tetrafluoroethanol and 120g of dichloromethane at room temperature until homogeneous, add 17g of pyridine and stir at room temperature for 10min to form the first solution.

[0057] (2) 30.5 g of trifluoromethyl sulfinyl chloride and 100 g of dichloromethane were mixed evenly to form a second solution. The second solution was added dropwise to the first solution at 0 °C for 1 h and reacted for 8 h to obtain the product. The product was filtered, and the filtrate was extracted with water, separated, dried over anhydrous magnesium sulfate, concentrated and distilled, and then vacuum dried at 50 °C for 10 h to obtain 46.2 g of compound five. The yield of compound five obtained was 93.1%, and the purity was 99%. Compound five was tested, and its... 1 H NMR (400MHz, CDCl3, ppm): δ 6.46 (tt, 1H), 3.83 (t, 2H).

[0058] (VI) Preparation of Compound VI (1) Mix 32g of 2,2,3,3,3-pentafluoroethanol and 120g of dichloromethane at room temperature until homogeneous, add 17g of pyridine and stir at room temperature for 10min to form the first solution.

[0059] (2) 30.5 g of trifluoromethyl sulfinyl chloride and 100 g of dichloromethane were diluted and mixed evenly to form a second solution. The second solution was added dropwise to the first solution at 0 °C for 1 h and reacted for 8 h to obtain the product. The product was filtered, and the filtrate was extracted with water, separated, dried over anhydrous magnesium sulfate, concentrated and distilled, and then vacuum dried at 50 °C for 10 h to obtain 44.5 g of compound VI. The yield of compound VI was 83.7%, and the purity was 99%. Compound VI was tested, and its... 1 H NMR (400MHz, CDCl3, ppm): δ3.83 (t, 2H).

[0060] Part Two: Applications of Fluorinated Sulfinates in Batteries 1.1 Preparation of non-aqueous electrolyte In a nitrogen-filled glove box (O2 < 1 ppm, H2O < 1 ppm), diethyl carbonate (DEC) and ethyl methyl carbonate (EMC) were mixed at a mass ratio of 1:1 to obtain a mixed solvent of 86 g. Then, 1.5 g of each of compounds one through six were added to obtain mixed solutions. The mixed solutions were sealed and packaged, then frozen in a freezer (-4°C) for 2 hours. After removal, 12.5 g of lithium hexafluorophosphate (LiPF6) was slowly added to the mixed solutions in a nitrogen-filled glove box (O2 < 1 ppm, H2O < 1 ppm). After thorough mixing, non-aqueous electrolytes 1-6# were prepared.

[0061] In a nitrogen-filled glove box (O2 < 1 ppm, H2O < 1 ppm), diethyl carbonate (DEC) and ethyl methyl carbonate (EMC) were mixed at a mass ratio of 1:1 to obtain a mixed solvent of 87.5 g, which was then used as the organic solvent. The organic solvent was sealed and packaged and frozen in a freezer (-4℃) for 2 hours. After being removed, 12.5 g of lithium hexafluorophosphate (LiPF6) was slowly added to the mixed solution in a nitrogen-filled glove box (O2 < 1 ppm, H2O < 1 ppm). After mixing thoroughly, non-aqueous electrolyte 7# was prepared.

[0062] In a nitrogen-filled glove box (O2 < 1 ppm, H2O < 1 ppm), diethyl carbonate (DEC) and ethyl methyl carbonate (EMC) were mixed at a mass ratio of 1:1 to obtain a mixed solvent of 86 g. Then, 1.5 g of a fluorosulfonate compound prepared from compound seven was added to obtain a mixed solution. The mixed solution was sealed and packaged, and frozen in a freezer (-4℃) for 2 hours. After removal, 12.5 g of lithium hexafluorophosphate (LiPF6) was slowly added to the mixed solution in a nitrogen-filled glove box (O2 < 1 ppm, H2O < 1 ppm). After thorough mixing, non-aqueous electrolyte #8 was prepared.

[0063]

[0064] Compound 7 In a nitrogen-filled glove box (O2 < 1 ppm, H2O < 1 ppm), diethyl carbonate (DEC) and ethyl methyl carbonate (EMC) were mixed at a mass ratio of 1:1 to obtain a mixed solvent of 86 g. Then, 1.5 g of a fluorosulfonate compound prepared from compound 8 was added to obtain a mixed solution. The mixed solution was sealed and packaged, then frozen in a freezer (-4℃) for 2 hours. After removal, 12.5 g of lithium hexafluorophosphate (LiPF6) was slowly added to the mixed solution in a nitrogen-filled glove box (O2 < 1 ppm, H2O < 1 ppm). After thorough mixing, non-aqueous electrolyte #9 was prepared.

[0065]

[0066] Compound 8 1.2 Preparation of the positive electrode Ternary material LiNi 0.5 Co 0.2 Mn 0.3 Zr 0.03 O2, conductive agent SuperP, binder PVDF and carbon nanotubes (CNT) are mixed evenly in a mass ratio of 96.5:1.5:1:1 to prepare a lithium-ion battery positive electrode slurry of a certain viscosity. After being coated on both sides of aluminum foil, the slurry is dried and rolled to obtain a positive electrode sheet, thus producing a lithium-ion battery positive electrode sheet that meets the requirements.

[0067] 1.3 Preparation of negative electrode Artificial graphite, conductive agent SuperP, thickener CMC, and binder SBR (styrene-butadiene rubber latex) are mixed in a mass ratio of 95:1.5:1.0:2.5 to form a slurry. The mixture is then coated on both sides of a copper foil, dried, and rolled to obtain a negative electrode sheet, thus producing a lithium-ion battery negative electrode sheet that meets the requirements.

[0068] 1.4 Preparation of Lithium-ion Batteries The positive electrode, negative electrode, and separator prepared according to the above process are stacked to form lithium-ion batteries with a thickness of 4.7 mm, a width of 55 mm, a length of 60 mm, and a total capacity of 2 Ah. These batteries are then vacuum-baked at 75°C for 10 hours and injected with non-aqueous electrolytes #1 to #9. After standing for 24 hours, they are charged to 3.65 V using a constant current of 0.1 C (200 mA), then charged at a constant voltage of 3.65 V until the current drops to 0.05 C (100 mA). They are then discharged to 2.5 V using 0.2 C (400 mA), and this charge-discharge cycle is repeated twice. Finally, the batteries are charged to 3.65 V using 0.1 C (200 mA), completing the fabrication of lithium-ion batteries #1 to #9.

[0069] Performance tests were conducted on lithium-ion batteries #1 to #9. The test results are shown in Table 1. The test conditions are as follows.

[0070] (1) High-rate cycling performance test Under normal temperature (25℃) conditions, the lithium-ion battery was subjected to one 3.0C / 3.0C charge and discharge cycle (the battery discharge capacity was recorded as C0), with an upper limit voltage of 4.1V; then, it was subjected to 500 cycles of 3.0C / 3.0C charge and discharge, and the capacity retention rate was calculated.

[0071] Capacity retention rate = (Battery capacity after 500 cycles C1 / Initial battery capacity C0) × 100% (2) Low-temperature discharge test Under normal temperature (25℃) conditions, a lithium-ion battery is subjected to a single 0.5 C / 0.5 charge-discharge cycle (battery cutoff voltage 3.0V, discharge capacity C0), with an upper limit voltage of 4.1V (cutoff current 0.05C). The battery is then fully charged to 4.1V at 0.5C (cutoff current 0.05C) at room temperature (25℃), and then transferred to -20℃ for 4 hours. It is then discharged at 0.5C to 3.0V, with a discharge capacity of C1. The capacity retention rate is calculated.

[0072] Capacity retention rate = (C1 / C0) × 100% Table 1 Electrochemical performance test results of lithium-ion batteries #1~#10

[0073] As shown in Table 1, lithium-ion batteries #1-6 have better rate performance and low-temperature performance than lithium-ion battery #7. This is because fluorinated sulfinates are added as additives to lithium-ion batteries #1-6. Fluorinated sulfinates include fluorinated alcohols and fluorinated sulfinyl skeletons, which combine the advantages of both fluorinated alcohols and fluorinated sulfinyls. They can form a good protective film at the interface of positive and negative electrode materials and have low internal resistance, thus improving the rate performance and low-temperature performance of the battery.

[0074] Furthermore, comparing lithium-ion batteries 1 through 6, it can be seen that lithium-ion battery 2 has the best performance. This may be because, compared with other compounds, compound 2 has a stronger electron-withdrawing functional group and a shorter branch chain, resulting in less steric hindrance and thus better performance.

[0075] Comparing the test results of lithium-ion batteries #1-6 and #8, it is evident that fluorosulfinates outperform fluorinated sulfonates as additives. This is likely due to the higher redox activity matching of sulfinates and the moderate S(=O)-O bond energy of sulfinates, which preferentially undergo reduction / oxidation decomposition on the positive and negative electrode surfaces within the electrochemical window of lithium batteries (0-4.5 V), promptly forming a protective film. In contrast, sulfonates have a higher S(=O)2-O bond energy, requiring a higher potential for decomposition, often missing the film-forming opportunity at the electrode interface, or even failing to decompose, thus failing to fulfill their additive role. Furthermore, the organic-inorganic hybrid film generated after the decomposition of sulfinates possesses both "density" and "lithium-ion conductivity," inhibiting continuous electrolyte decomposition while ensuring rapid ion migration. Sulfonate decomposition often produces inorganic salt deposits such as Li2SO4 and Li2SO3, or excessively polymerized organic films, either forming an insulating layer or exhibiting large film porosity, leading to a surge in interfacial impedance. In addition, the trifluoromethyl and other strong electron-withdrawing groups of fluorosulfinates further reduce the electron cloud density of the molecule, enhance the film-forming priority, and can also introduce fluorine into the film layer, improving the stability and ion conductivity of the film; while fluorosulfinates are inherently inert in decomposition, and even if fluorine groups are introduced, it is difficult to change the problem of film-forming hysteresis.

[0076] Comparing the test results of lithium-ion batteries #1-6 and #9, it is evident that when the alcohol in fluorosulfinic acid ester compounds is replaced by an alkane, the right side lacks the assistance of a fluorinated electron-withdrawing group, with only the trifluoromethyl group on the left providing electron-withdrawing properties. The overall redox activity of the molecule is weaker than that of compounds #1-6, significantly reducing the timeliness and priority of film formation, potentially preventing the timely formation of an effective protective film on the electrode surface. In lithium-ion battery #9, because compound #8 has no fluorine at the alkoxy end, the decomposition products contain even lower fluorine content, making the film more prone to organic polymer characteristics, resulting in a porous film, higher impedance, and a significant increase in lithium-ion transport resistance. In contrast, double-ended fluorine substitution introduces more fluorine into the film, forming a denser fluorine-containing organic-inorganic hybrid film with smoother lithium-ion conduction channels and lower interfacial impedance. Simultaneously, the decomposition products of fluorine substitution better inhibit the continuous decomposition of the electrolyte, reducing film thickening and porosity formation. The high-fluorine-content interfacial films formed by compounds #1-6 maintain good ion conduction efficiency at low temperatures, reducing lithium-ion migration obstacles, and exhibiting superior low-temperature discharge capacity and rate performance. The low-fluorine film of compound 8 exhibits a more significant decrease in ion conduction efficiency at low temperatures. During high-rate charging and discharging, the resistance to lithium-ion insertion / extraction is further amplified, leading to accelerated degradation of battery rate and low-temperature performance, resulting in poor performance.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, it is not limited to those listed in the embodiments. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A fluoro-sulfinic acid ester compound, characterized by, a compound represented by Structural Formula I, wherein R is selected from the group consisting of C1-C6 fluoroalkyl, 。 2. The fluoro-sulfinic acid ester compound according to claim 1, wherein at least one selected from the group consisting of Compound 1 to Compound 6, 。 3. The method for producing a fluoro-sulfinic acid ester compound according to any one of claims 1 or 2, characterized by, comprising the steps of: (1) mixing a compound represented by Structural Formula II, an organic base and a first solvent at room temperature to form a first solution; (2) mixing a compound represented by Structural Formula III and a second solvent to form a second solution, dropping the second solution into the first solution at a certain temperature to react, purifying and drying the product, 。 4. The method for producing a fluoro-sulfinic acid ester compound according to claim 3, wherein the first solvent and the second solvent are each independently selected from at least one of the group consisting of nitrile solvents, halogenated hydrocarbon solvents, ether solvents, ester solvents, ketone solvents and aromatic hydrocarbon solvents.

5. The method for preparing fluorosulfinic acid esters according to claim 3, characterized in that, the certain temperature is -10-30℃, the dropping time is 10-60min, and the reaction time is 1-24h.

6. The method for preparing fluorosulfinic acid esters according to claim 3, characterized in that, the molar ratio of the compound represented by Structural Formula II to the compound represented by Structural Formula III is 1.0-2.5:1.

0.

7. The method for preparing fluorosulfinic acid esters according to claim 3, characterized in that, the organic base is selected from at least one of the group consisting of pyridine, triethylamine, imidazole, 4-dimethylaminopyridine and tetramethylguanidine, and the molar ratio of the compound represented by Structural Formula II to the organic base is 1.0:1.0-3.

0.

8. A non-aqueous electrolyte solution comprising an electrolyte salt, a non-aqueous organic solvent and an additive, wherein the additive comprises the fluoro-sulfinic acid ester compound according to any one of claims 1-2.

9. The nonaqueous electrolyte according to claim 8, wherein The mass ratio of the fluoro-sulfinic acid ester compound in the non-aqueous electrolyte solution is 0.1-2.5%.

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