Sulfonylpyridinium salt compounds, methods for preparing the same, and electrolytes

Abstract

The application provides a sulfonic pyridine compound and a preparation method and an electrolyte thereof. The structural formula of the sulfonic pyridine compound is shown in formula I or formula II. Wherein, R1, R2, R3, R4 and R5 are each independently selected from one of H, CN, NO2, halogen, C1-C4 hydrocarbon group, C1-C4 halogenated hydrocarbon group, NH2, OH, COOH, CH2C6H5 and SO2F. The sulfonic pyridine compound can form a good protective film on the interface of the positive and negative electrode materials, has a small internal resistance, and can improve the rate and low-temperature performance of the battery, and can be used as an electrolyte additive with excellent performance. Formula I Formula II

Description

Technical Field

[0001] This invention relates to the field of materials synthesis technology, and more particularly to a compound used in batteries, and even more particularly to a sulfonate pyridine salt compound, its preparation method, and an 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, it 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 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. Studies have reported that adding additives that can form films at the interface of ternary positive electrode materials (such as organic additives VC, PS, DTD, TMSP; and inorganic additives LiPO2F2, LiFSI, LiTFSI, LiPF2(C2O4)2, LiBOB, etc.) can effectively protect the positive electrode, improve the electrolyte's voltage withstand window, and enhance battery cycle life. Studies have found that these additives can form a CEI film not only at the cathode material interface but also a SEI film at the graphite anode interface, leading to increased internal resistance and affecting the battery's rate capability and low-temperature performance. Given the shortcomings of currently available commercial electrolyte additives, it is necessary to develop new additives.

[0003] Amphoteric compounds are molecules that carry both positive and negative charges but are electrically neutral; the most representative type of such substances is amino acids. + H3NCH2COO - ), where the positive charge center is -NH3. + The negative charge center is -COO - Overall, zwitterions are electrically neutral. Current research focuses on replacing the negatively charged center with sulfonate or phosphate groups, attaching different functional groups to sulfonate or phosphate groups, or polymerizing them to form zwitterionic polymers to achieve different functions, such as sulfobetaine and phosphocholine. However, the variety of usable zwitterionic compounds is currently limited, with relatively simple structures and properties, especially zwitterionic compounds based on sulfonate and pyridine and their derivatives, which are rarely reported. Summary of the Invention

[0004] Based on the above problems, the purpose of the present application is to provide a sulfonic acid pyridine salt compound, a preparation method thereof and an electrolyte, which can form a good protective film at the interface of positive and negative electrode materials and has a small internal resistance to improve the rate and low temperature performance of the battery, and can be used as an electrolyte additive with excellent performance.

[0005] To achieve the above purpose, the present application provides a sulfonic acid pyridine salt compound in the first aspect, which has a structural formula as shown in formula I or formula II, wherein R1, R2, R3, R4 and R5 are each independently selected from one of H, CN, NO2, halogen, C1-C4 hydrocarbon group, C1-C4 halogenated hydrocarbon group, NH2, OH, COOH, CH2C6H5 and SO2F.

[0006]

[0007] Formula I Formula II

[0008] The sulfonic acid pyridine salt compound of the present application is a compound as shown in formula I or formula II, which includes a sulfonic acid group and a pyridine ring, and has the advantages of both ionic liquids and sulfonic acid groups, can form a good protective film at the interface of positive and negative electrode materials, and has a small internal resistance to improve the rate and low temperature performance of the battery, and has a good application prospect.

[0009] As a technical solution of the present application, R1, R2, R3, R4 and R5 are each independently selected from one of H, CN, F, CH=CH2 and CH3.

[0010] As a technical solution of the present application, the sulfonic acid pyridine salt compound is at least one of compound one to compound six.

[0011]

[0012] Compound one Compound two

[0013]

[0014] Compound three Compound four

[0015]

[0016] Compound five Compound six

[0017] The present application provides a preparation method of the sulfonic acid pyridine salt compound in the second aspect, which includes the following steps:

[0018] (1) mixing a compound as shown in formula III and a first solvent at a certain temperature to form a first solution;

[0019] (2) mixing the sulfolane compound and a second solvent to form a second solution, dropping the second solution into the first solution to react, and obtaining a product, and purifying and drying the product.

[0020]

[0021] Formula III

[0022] wherein, R1, R2, R3, R4 and R5 are each independently selected from one of H, CN, NO2, halogen, C1-C4 hydrocarbon group, C1-C4 halogenated hydrocarbon group, NH2, OH, COOH, CH2C6H5 and SO2F.

[0023] The preparation method of the present application adopts a sulfolane compound to modify pyridine and its derivative molecules as shown in Formula III, and synthesizes a series of sulfonic acid pyridine onium salt compounds with novel structures, the preparation method has the advantages of easy preparation of raw materials, simple process, high yield, high purity, good atomic economy, and easy industrial production. The prepared sulfonic acid pyridine onium salt compound can improve the low temperature and rate performance of the battery.

[0024] As a technical scheme of the present application, 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.

[0025] As a technical scheme of the present application, the first solvent and the second solvent are each independently selected from at least one of acetonitrile, butyronitrile, 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.

[0026] As a technical scheme of the present application, the temperature is -10-30℃, and the holding time is 10-60 min.

[0027] As a technical scheme of the present application, the molar ratio of the sulfolane compound to the compound shown in Formula III is 1:1.0-1.2.

[0028] As a technical scheme of the present application, the sulfolane compound is propane sulfolane or propylene sulfolane.

[0029] As a technical scheme of the present application, the purification includes filtering and / or washing, the drying temperature is 35-120℃, and the drying time is 1-24 h.

[0030] The third aspect of the present application provides an electrolyte, comprising a non-aqueous organic solvent, an electrolyte salt and an additive,

[0031] The additive comprises the aforementioned pyridinium sulfonate salt compound, and the pyridinium sulfonate salt compound accounts for 0.1-2.5% of the mass of the electrolyte. DETAILED DESCRIPTION

[0032] The pyridinium sulfonate salt compound of the present application can be used as an intermediate to synthesize electroplating additives, polycarbonate fire retardants, lubricating grease thickeners, polypropylene antistatic agents, polyethylene imine crosslinking agents, etc. In addition, the pyridinium sulfonate salt compound can also be used as a functional additive, such as a synergistic antibacterial agent, a printing and dyeing finishing agent, a leather brightener, an electrolyte additive, etc. The use of the pyridinium sulfonate salt compound as an electrolyte additive in lithium ion batteries can improve the low-temperature, rate, etc. electrochemical performance of lithium ion batteries.

[0033] The lithium ion battery comprises a positive electrode active material, a negative electrode active material and an electrolyte. 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 a lithium cobalt oxide (such as LiCoO2), a lithium nickel oxide (such as LiNiO2), a lithium manganese oxide (such as LiMnO2, LiMn2O4), a lithium nickel cobalt oxide, a lithium manganese cobalt oxide, a lithium nickel manganese oxide, a lithium nickel cobalt manganese oxide (chemical formula: LiNi x Co y Mn (1-x-y) M z O2, wherein 0.6≤x<0.9, x+y<1, 0≤z<0.08, M is at least one of Al, Mg, Zr and Ti) and a coating and a doped material of the above-mentioned materials. It is especially suitable for lithium nickel cobalt manganese oxide ternary materials. These positive electrode active materials can be used alone or in combination with two or more.

[0034] The negative electrode active material comprises at least one of a carbon-based material, a silicon-based material and a tin-based material. The carbon-based material can be but is not limited to at least one of artificial graphite, natural graphite, hard carbon, soft carbon, graphene and mesocarbon microbeads. The silicon-based material can be but is not limited to at least one of silicon single substance, silicon-oxygen composite material, silicon-carbon composite material and silicon alloy material. The tin-based material can comprise tin single substance, tin-carbon composite material, tin-oxygen composite material and tin alloy compound.

[0035] The electrolyte comprises an electrolyte salt, a non-aqueous organic solvent and an additive.

[0036] The electrolyte salt can be, but is not limited to, at least one of lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium bisfluorosulfonylimide (LiFSI), lithium bis-trifluoromethylsulfonylimide (LiTFSI), lithium methanesulfonate (LiCH3SO3), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(oxalato)borate (C4BLiO8), lithium difluoro(oxalato)borate (C2BF2LiO4), lithium difluorophosphate (LiPO2F2), and lithium difluorobis(oxalato)phosphate (LiDFBP). The non-aqueous organic solvent is selected from at least one of carbonates and / or carboxylic acid esters. Further, the non-aqueous organic solvent is selected from at least one of vinyl carbonate (PC), 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.

[0037] The additive can include at least a pyridinium sulfonate compound. Further, the pyridinium sulfonate compound has a structural formula as shown in Formula I or Formula II, wherein R1, R2, R3, R4, and R5 are each independently selected from one of H, CN, NO2, halogen, C1-C4 hydrocarbon group, C1-C4 halogenated hydrocarbon group, NH2, OH, COOH, CH2C6H5, and SO2F. More preferably, R1, R2, R3, R4, and R5 are each independently selected from one of H, CN, F, CH=CH2, and CH3.

[0038]

[0039] Formula I Formula II

[0040] Further, the pyridinium sulfonate compound is at least one of Compound One to Compound Six.

[0041] Compound One Compound Two

[0042]

[0043] Compound Three Compound Four

[0044]

[0045] Compound Five Compound Six

[0046] The pyridinium sulfonate compound accounts for 0.1-2.5% of the mass of the electrolyte. As an example, the pyridinium sulfonate compound can 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%, 2.5%.

[0047] The method for preparing the pyridine sulfonate compound of the present application can comprise the following steps.

[0048] (1) mixing a compound shown in formula III and a first solvent at a certain temperature to form a first solution.

[0049] (2) mixing a sulfonic lactone compound and a second solvent to form a second solution, dropping the second solution into the first solution to react, and purifying and drying the product.

[0050] The reaction process of the pyridine sulfonate compound of the present application is shown as follows. Wherein R6 is C n H 2n or C n H n , and n is an integer greater than or equal to 2.

[0051]

[0052] In step (1), the compound shown in formula III is shown in the following structural formula. Wherein R1, R2, R3, R4 and R5 are each independently selected from one of H, CN, NO2, halogen, C1-C4 hydrocarbon group, C1-C4 halogenated hydrocarbon group, NH2, OH, COOH, CH2C6H5 and SO2F. Further, R1, R2, R3, R4 and R5 are each independently selected from one of H, CN, F, CH=CH2 and CH3.

[0053]

[0054] Formula III

[0055] Further, the compound shown in formula III is at least one of compound seven to compound eleven.

[0056] Compound seven Compound eight Compound nine

[0057]

[0058] Compound ten Compound eleven

[0059] The first solvent is selected from at least one of a nitrile solvent, a halogenated hydrocarbon solvent, an ether solvent, an ester solvent, a ketone solvent, and an aromatic hydrocarbon solvent. Further, the first solvent is selected from at least one of acetonitrile, butyronitrile, dichloromethane, trichloromethane, 1,2-dichloroethane, tetrachloroethane, methyl tert-butyl ether, ethylene glycol dimethyl ether, tetrahydrofuran, dioxane, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl acetate, ethyl acetate, propyl acetate, acetone, cyclohexanone, 4-methyl-2-pentanone, benzene, xylene, and toluene.

[0060] In step (1), the first solution needs to be kept at a certain temperature to prevent the reaction with the sulfolane compound from being too fast. The certain temperature is -10 to 30°C, preferably -10 to 10°C, and as an example, the certain temperature can be, but is not limited to, -10°C, -5°C, 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C. The holding time is 10 to 60 min, and as an example, the time can be, but is not limited to, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min.

[0061] In step (2), the sulfolane compound has a structural formula as shown in Formula IV, wherein R6is C n H 2n or C n H n , and n is an integer greater than or equal to 2. Further, the sulfolane compound is propane sulfolane or propenyl sulfolane.

[0062] Formula IV

[0063] The second solvent can be the same as or different from the first solvent. Further, the second solvent is selected from at least one of a nitrile solvent, a halogenated hydrocarbon solvent, an ether solvent, an ester solvent, a ketone solvent, and an aromatic hydrocarbon solvent. Further, the second solvent is selected from at least one of acetonitrile, butyronitrile, dichloromethane, trichloromethane, 1,2-dichloroethane, tetrachloroethane, methyl tert-butyl ether, ethylene glycol dimethyl ether, tetrahydrofuran, dioxane, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl acetate, ethyl acetate, propyl acetate, acetone, cyclohexanone, 4-methyl-2-pentanone, benzene, xylene, and toluene.

[0064] The molar ratio of the sulfolactone compound to the compound of Formula III is 1:1.0-1.2, and as an example, the molar ratio can be but is not limited to 1:1.0, 1:1.1, 1:1.2. The second solution is added dropwise into the first solution to control the reaction speed, and the reaction time is 1-24 h, and as an example, the reaction time can be but is not limited to 1 h, 3 h, 5 h, 7 h, 9 h, 10 h, 12 h, 14 h, 16 h, 18 h, 20 h, 22 h, 24 h.

[0065] The purification includes filtration and / or washing, the filtration can adopt centrifugal stratification, reduced pressure filtration or general filtration, the washing can adopt multiple washing with aqueous hydrochloric acid, saturated brine or water. The drying can be operated by air blowing drying, the drying temperature is 35-120℃, and as an example, the temperature can be but is not limited to 35℃, 45℃, 55℃, 65℃, 75℃, 85℃, 95℃, 105℃, 110℃, 115℃, 120℃. The drying time is 1-24 h, and not limited to 1 h, 3 h, 5 h, 7 h, 9 h, 10 h, 12 h, 14 h, 16 h, 18 h, 20 h, 22 h, 24 h.

[0066] In order to better illustrate the purpose, technical scheme and beneficial effects of the present application, the present application will be further described below in combination with specific examples. It should be noted that the following implementation of the method is a further explanation of the present application and should not be regarded as a limitation of the present application.

[0067] First part: preparation of pyridine sulfonic acid salt compound

[0068] Example 1

[0069] This example is to prepare a pyridine sulfonic acid salt compound, and the preparation method thereof includes the following steps.

[0070] (1) 19.7 g of compound seven and 80 g of dichloromethane are stirred at 0℃ for 10 min to form a first solution.

[0071] (2) 30.3 g of propane sulfolactone (R6 is CH2-CH2) and 80 g of dichloromethane are mixed uniformly to form a second solution, the second solution is added dropwise into the first solution to react for 20 h to obtain a product, the product is filtered, washed with dichloromethane, and vacuum dried at 60℃ for 10 h to obtain 45.9 g of compound one.

[0072] The yield of the prepared compound one is 91.8%, and the purity is 99%.

[0073] The compound one is used to prepare a compound two. 1H NMR (400MHz, Deuterium DMSO, ppm): 5.69-5.72 (d, J = 3.2 Hz, 2H), 6.56-6.59 (d, J = 3.4 Hz, 1H), 6.84-6.88 (m, J = 3.6 Hz, 1H), 8.23-8.26 (t, J = 3.1 Hz, 2H), 8.73-8.76 (m, J = 3.8 Hz, 1H), 9.04-9.06 (d, J = 3.2 Hz, 2H).

[0074] Compound one 13 C-NMR (100 MHz, Deuterium DMSO, ppm): δ 21.2, 56.2, 56.4, 128.4, 146.0, 146.1.

[0075] Example 2

[0076] This example is to prepare a sulfonic acid pyridine compound, and the preparation method comprises the following steps.

[0077] (1) 19.9 g of compound seven and 80 g of dichloromethane are stirred at 0°C for 10 min to form a first solution.

[0078] (2) 30.1 g of propylene sulfone (R6 is CH=CH) and 80 g of dichloromethane are mixed uniformly to form a second solution, and the second solution is added dropwise into the first solution to react for 20 h to obtain a product, and the product is filtered, washed with dichloromethane, and vacuum dried at 60°C for 10 h to obtain 46.1 g of compound two.

[0079] The yield of the prepared compound two is 92.2%, and the purity is 99%.

[0080] Compound two 1 H NMR (400MHz, Deuterium DMSO, ppm): 5.69-5.72 (d, J = 3.2 Hz, 2H), 6.56-6.59 (d, J = 3.4 Hz, 1H), 6.84-6.88 (m, J = 3.6 Hz, 1H), 8.23-8.26 (t, J = 3.1 Hz, 2H), 8.73-8.76 (m, J = 3.8 Hz, 1H), 9.04-9.06 (d, J = 3.2 Hz, 2H).

[0081] Compound two 13 C-NMR (100 MHz, Deuterium DMSO, ppm): δ 54, 127.8, 128.4, 134.5, 146.1.

[0082] Example 3

[0083] This example is to prepare a sulfonic acid pyridine compound, and the preparation method comprises the following steps.

[0084] (1) 23.1 g of compound eight and 65 g of tetrahydrofuran were stirred at 0 °C for 10 min to form a first solution.

[0085] (2) 26.9 g of propane sulfonic acid lactone (R6 is CH2-CH2) and 70 g of tetrahydrofuran were mixed to form a second solution, the second solution was added dropwise into the first solution to react for 2 h to obtain a product, the product was filtered, washed with tetrahydrofuran, and dried at 70 °C under vacuum for 8 h to obtain 44.0 g of compound three.

[0086] The yield of the prepared compound three was 88.0%, and the purity was 99%.

[0087] The compound three had the following properties: 1 H NMR (400 MHz, deuterated DMSO, ppm): 2.55-2.59 (m, J = 3.9 Hz, 4H), 5.01-5.04 (t, J = 4.2 Hz, 2H), 5.44-5.46 (dd, J = 2, 8 Hz, 1H), 5.89-5.91 (dd, J = 3.8 Hz, 1H), 6.62-6.64 (dd, J = 3.2 Hz, 1H), 7.29-7.31 (m, J = 3.1 Hz, 1H), 8.11-8.15 (m, J = 4.2 Hz, 2H), 8.93-8.95 (d, J = 3.7 Hz, 1H).

[0088] The compound three had the following properties: 13 C-NMR (100 MHz, deuterated DMSO, ppm): δ 21.1, 54.3, 56.1, 120.3, 127.1, 135.8, 145.8, 147.1, 148.4.

[0089] Example 4

[0090] This example is to prepare a pyridine sulfonic acid salt compound, and the preparation method comprises the following steps.

[0091] (1) 22.1 g of compound nine and 80 g of dichloromethane were stirred at 10 °C for 20 min to form a first solution.

[0092] (2) 27.9 g of propane sulfonic acid lactone (R6 is CH2-CH2) and 80 g of dichloromethane were mixed to form a second solution, the second solution was added dropwise into the first solution to react for 16 h to obtain a product, the product was filtered, washed with dichloromethane, and dried at 60 °C under vacuum for 10 h to obtain 46.8 g of compound four.

[0093] The yield of the prepared compound four was 93.6%, and the purity was 99%.

[0094] The compound four had the following properties: 1H NMR (400 MHz, deuterated DMSO, ppm): 2.55-2.59 (m, J = 3.8 Hz, 4H), 5.01-5.04 (m, J = 4.2 Hz, 2H), 8.79-8.81 (t, J = 2.8 Hz, 1H), 9.02-9.20 (m, J = 3.6 Hz, 2H), 9.28-9.30 (m, J = 2.2 Hz, 1H).

[0095] Compound four 13 C-NMR (100 MHz, deuterated DMSO, ppm): δ 20.2, 53.1, 56.1, 117.0, 126.6, 132.0, 134.0, 147.4, 147.1.

[0096] Example 5

[0097] This example is to prepare a pyridine sulfonic acid compound, and the preparation method comprises the following steps.

[0098] (1) 23.0 g of compound ten and 80 g of dichloromethane were stirred at 0°C for 10 min to form a first solution.

[0099] (2) 27.0 g of propane sulfonic acid lactone (R6 is CH2-CH2) and 100 g of acetonitrile were mixed uniformly to form a second solution, and the second solution was added dropwise into the first solution to react for 16 h to obtain a product. The product was filtered, washed with dichloromethane, and vacuum dried at 70°C for 9 h to obtain 42.2 g of compound five.

[0100] The yield of the prepared compound five is 84.4%, and the purity is 99%.

[0101] Compound five 1 H NMR (400 MHz, deuterated DMSO, ppm): 2.55-2.59 (m, J = 3.8 Hz, 4H), 5.01-5.04 (m, J = 4.2 Hz, 2H), 8.79-8.81 (t, J = 2.8 Hz, 1H), 9.02-9.20 (m, J = 3.6 Hz, 2H), 9.28-9.30 (m, J = 2.2 Hz, 1H).

[0102] Compound five 13 C-NMR (100 MHz, deuterated DMSO, ppm): δ 20.2, 53.1, 56.1, 117.0, 126.6, 132.0, 134.0, 147.4, 147.1.

[0103] Example 6

[0104] The present embodiment is to prepare a pyridinium sulfonate compound, and the preparation method comprises the following steps.

[0105] (1) 21.7 g of compound eleven and 80 g of dichloromethane were stirred at 0°C for 10 min to form a first solution.

[0106] (2) 28.3 g of propane sulfone (R6 is CH2-CH2) and 80 g of dichloromethane were mixed uniformly to form a second solution, and the second solution was added dropwise into the first solution for reaction for 20 h to obtain a product, which was filtered, washed with dichloromethane, and vacuum dried at 70°C for 6 h to obtain 44.5 g of compound six.

[0107] The yield of the prepared compound six was 89.0%, and the purity was 99%.

[0108] The compound six has the following properties: 1 H NMR (400 MHz, deuterated DMSO, ppm): 2.55-2.59 (m, J = 3.8 Hz, 4H), 2.91-2.93 (s, J = 1.8 Hz, 3H), 5.01-5.03 (t, J = 2.8 Hz, 2H), 8.08-8.10 (m, J = 2.8 Hz, 1H), 8.29-8.32 (dd, J = 1.6 Hz, 1H), 8.63-8.65 (m, J = 2.2 Hz, 1H), 8.97-9.00 (m, J = 1.2 Hz, 1H).

[0109] The compound six has the following properties: 13 C-NMR (100 MHz, deuterated DMSO, ppm): δ 20.5, 53.9, 56.1, 125.4, 126.4, 146.6, 155.1.

[0110] Second part: application of the pyridinium sulfonate compound in a battery

[0111] 1.1 Preparation of a non-aqueous electrolyte

[0112] In a glove box filled with nitrogen (O2<1 ppm, H2O<1 ppm), 86 g of a mixed solvent obtained by uniformly mixing diethyl carbonate (DEC) and methyl ethyl carbonate (EMC) in a mass ratio of 1:1 was used as an organic solvent, and 1.5 g of the pyridinium sulfonate compound prepared in Examples 1-6 was added to obtain a mixed solution. The mixed solution was sealed, packaged, and placed in a quick-freezing interval (-4°C) for freezing for 2 h, and then taken out. In a glove box filled with nitrogen (O2<1 ppm, H2O<1 ppm), 12.5 g of lithium hexafluorophosphate (LiPF6) was slowly added to the mixed solution, and the mixture was uniformly mixed to obtain non-aqueous electrolytes 1-6#.

[0113] In a glove box filled with nitrogen (O2<1 ppm, H2O<1 ppm), 87.5 g of a mixed solvent obtained by mixing diethyl carbonate (DEC) and methyl ethyl carbonate (EMC) in a mass ratio of 1:1 was used as an organic solvent. The organic solvent was sealed and placed in a freezer (-4°C) for 2 h, and then taken out in a glove box filled with nitrogen (O2<1 ppm, H2O<1 ppm). 12.5 g of lithium hexafluorophosphate (LiPF6) was slowly added to the mixed solution, and the non-aqueous electrolyte 7# was prepared after mixing.

[0114] 1.2 Preparation of the positive electrode sheet

[0115] The ternary material LiNi 0.5 Co 0.2 Mn 0.3 Zr 0.03 O2, a conductive agent Super P, a binder PVDF, and carbon nanotubes (CNT) were mixed in a mass ratio of 96.5:1.5:1:1 to prepare a lithium ion battery positive electrode slurry with a certain viscosity. After coating on both sides of an aluminum foil, drying, and rolling, a positive electrode sheet was obtained, and a lithium ion battery positive electrode sheet meeting the requirements was prepared.

[0116] 1.3 Preparation of the negative electrode sheet

[0117] The artificial graphite, a conductive agent Super P, a thickening agent CMC, and a binder SBR (styrene-butadiene rubber emulsion) were mixed in a mass ratio of 95:1.5:1.0:2.5 to prepare a slurry. After coating on both sides of a copper foil with the mixed slurry, drying, and rolling, a negative electrode sheet was obtained, and a lithium ion battery negative electrode sheet meeting the requirements was prepared.

[0118] 1.4 Preparation of the lithium ion battery

[0119] The positive electrode sheet, the negative electrode sheet, and the separator prepared according to the above process were stacked to prepare a lithium ion battery with a thickness of 4.7 mm, a width of 55 mm, a length of 60 mm, and a total capacity of 2 Ah. The lithium ion battery was vacuum baked at 75°C for 10 h, and then injected with the non-aqueous electrolyte 1-7#. After standing for 24 h, the battery was charged to 3.65 V at a constant current of 0.1 C (200 mA), and then charged to a current of 0.05 C (100 mA) at a constant voltage of 3.65 V. Then, the battery was discharged to 2.5 V at 0.2 C (400 mA), and the above process was repeated twice. Finally, the battery was charged to 3.65 V at 0.1 C (200 mA), and the lithium ion battery 1-7# was prepared.

[0120] The lithium ion batteries 1-7# were tested for performance, and the test results are shown in Table 1. The test conditions are as follows.

[0121] (1) High-rate cycle performance test

[0122] At room temperature (25℃), the lithium ion battery was charged and discharged once at 3.0C / 3.0C (the battery discharge capacity was recorded as C0), and the upper voltage was 4.1V; then the battery was charged and discharged at 3.0C / 3.0C for 500 cycles, and the capacity retention rate was calculated.

[0123] Capacity retention rate = (battery capacity after 500 cycles C1 / battery initial capacity C0) * 100%

[0124] (2) Low temperature discharge test

[0125] At room temperature (25℃), the lithium ion battery was charged and discharged once at 0.5C / 0.5 (the battery cutoff voltage was 3.0V, and the discharge capacity was C0), and the upper voltage was 4.1V (cutoff current 0.05C). Then the battery was charged at 0.5C to 4.1V (cutoff current 0.05C) at room temperature (25℃), and then the battery was transferred to-20℃ for 4h, and discharged at 0.5C to 3.0V, and the discharge capacity was C1, and the capacity retention rate was calculated.

[0126] Capacity retention rate = (C1 / C0) * 100%

[0127] Table 1: Electrochemical performance test results of each example

[0128]

[0129] From the results in Table 1, the rate and low temperature performance of lithium ion batteries 1-6# are better than that of lithium ion battery 7#, because the lithium ion batteries 1-6# use a pyridinium sulfonate compound as an additive, and the pyridinium sulfonate compound includes a sulfonic acid group and a pyridine ring, which has the advantages of both ionic liquids and sulfonic acid groups, and can form a good protective film on the positive and negative electrode material interface, and has a small internal resistance, so as to improve the rate and low temperature performance of the battery.

[0130] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit the scope of protection of the present application, although the present application has been described in detail with reference to the preferred embodiments, but it is not limited to the examples listed in the embodiments, and those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A sulfonic acid pyridinium salt compound, characterized by, Compound two, Compound two.

2. The method of preparing a sulfonic acid pyridinium salt compound according to claim 1, characterized by, The method comprises the steps of: (1) mixing compound seven and a first solvent to form a first solution at a certain temperature; (2) mixing a sulfolactone compound and a second solvent to form a second solution, dropping the second solution into the first solution for reaction, purifying and drying the product, Compound seven.

3. The method for preparing the sulfonate pyridine salt compound according to claim 2, characterized in that, The first solvent and the second solvent are each independently selected from at least one of a nitrile solvent, a halogenated hydrocarbon solvent, an ether solvent, an ester solvent, a ketone solvent and an aromatic hydrocarbon solvent.

4. The method for preparing the sulfonate pyridine salt compound according to claim 2, characterized in that, The certain temperature is -10-30°C, and the holding time is 10-60 min.

5. The method for preparing the sulfonate pyridine salt compound according to claim 2, characterized in that, The molar ratio of the sulfolactone compound to the compound seven is 1:1.0-1.

2.

6. The method of claim 2, wherein the sulfonic acid pyridinium salt compound is prepared by the process comprising: reacting a pyridine compound with a sulfonic acid compound in the presence of a base to form a sulfonic acid pyridinium salt compound; and isolating the sulfonic acid pyridinium salt compound. The sulfolactone compound is propenyl sulfolactone.

7. The method for preparing the sulfonate pyridine salt compound according to claim 2, characterized in that, The purification comprises filtering and / or washing, the drying temperature is 35-120°C, and the drying time is 1-24 h.

8. An electrolyte solution comprising a non-aqueous organic solvent, an electrolyte salt and an additive, characterized in that, The additive comprises the sulfonated pyridine compound of claim 1, and the sulfonated pyridine compound accounts for 0.1-2.5% of the mass of the electrolyte solution.

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