Imidazolium zwitterionic compounds, methods of making, and use in batteries

Abstract

The application provides an imidazole zwitterionic compound, a preparation method thereof and application thereof in a battery. The structural formula of the imidazole zwitterionic compound is shown in formula I, R1 is halogen, an aromatic group or a halogen-substituted aromatic group, R2, R3, R4 and R5 are each independently selected from H, halogen, CN, NO2, NH2, OH, COOH, SO2F, C1-C4 hydrocarbon groups and halogen-substituted C1-C4 hydrocarbon groups. The preparation method of the imidazole zwitterionic compound comprises the following steps: mixing a compound shown in formula II and a first solvent to form a first solution; dropwise mixing the first solution and a second solution and performing reaction to obtain a primary product, the second solution is a mixed solution of a sulfonic acid isocyanate compound shown in formula III and the first solvent; and purifying and drying the primary product. The imidazole zwitterionic compound, as a new substance, has the advantages of both ionic liquids and sulfonimide groups, has a good application prospect and can be applied to secondary batteries.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material synthesis, in particular to a compound applied in a battery, more particularly to an imidazole zwitterionic compound and a preparation method thereof, and application of the imidazole zwitterionic compound in a battery and the preparation method thereof. BACKGROUND

[0002] Zwitterionic compound refers to a molecule with both positive and negative charges but electrically neutral, and the most representative one is amino acid (H3NCH2COO-), in which the positive center is NH3+, and the negative center is COO-. + - + - Currently, the zwitterionic compounds that are studied more are those in which the negative center is replaced by a sulfonate group or a phosphate group, or different functional groups are connected to the sulfonate group or the phosphate group, or a zwitterionic polymer is formed to realize different functions, such as sulfobetaine and phosphocholine.

[0003] Therefore, developing new zwitterionic compounds and expanding their application range have become the common goal of the academic and industrial circles. SUMMARY

[0004] In view of the above problems, the present application provides an imidazole zwitterionic compound and a preparation method thereof, and application of the imidazole zwitterionic compound in a battery.The preparation method is simple in operation, and the yield and purity of the target product are high.The imidazole zwitterionic compound as a new substance contains an imide group and an imidazole ring, and has the advantages of both ionic liquids and sulfonimide groups, and has good application prospects and can be applied in secondary batteries.

[0005] To achieve the above-mentioned purpose, the present application provides an imidazole zwitterionic compound in a first aspect, the structural formula is shown as formula one, R1 is halogen, aromatic group or halogen-substituted aromatic group, R2, R3, R4 and R5 are each independently selected from H, halogen, CN, NO2, NH2, OH, COOH, SO2F, C1-C4 hydrocarbon group and halogen-substituted C1-C4 hydrocarbon group.

[0006] The imidazole zwitterionic compound of the present application as a new substance contains an imide group and an imidazole ring, and has the advantages of both ionic liquids and sulfonimide groups, and has good application prospects and can be applied in secondary batteries.

[0007] ​As a technical scheme of the present application, R1 is fluorine, chlorine, alkyl benzene or halogen-substituted alkyl benzene, R2, R3, R4 and R5 are each independently selected from H, fluorine, chlorine, CN, NO2, NH2, OH, COOH, C1-C4 alkyl, halogen-substituted C1-C4 alkyl.

[0008] As a technical scheme of the present application, at least one of compounds one to seven is included.

[0009]

[0010]

[0011] The second aspect of the present application provides a preparation method of imidazole zwitterionic compound, comprising the steps of:

[0012] (1) mixing the compound shown in formula two and the first solvent to form a first solution;

[0013] (2) dropwise mixing and reacting the first solution and a second solution to obtain a primary product, the second solution being a mixed solution of a sulfonic acid isocyanate compound shown in formula three and the first solvent;

[0014] (3) purifying and drying the primary product,

[0015]

[0016] wherein R2, R3, R4 and R5 are each independently selected from H, halogen, CN, NO2, NH2, OH, COOH, SO2F, C1-C4 hydrocarbon group, halogen-substituted C1-C4 hydrocarbon group, and R1 is halogen, aromatic group or halogen-substituted aromatic group.

[0017] The preparation method of the present application is simple, and the target product with high yield and purity can be obtained by reacting the imidazole compound shown in formula two and the sulfonic acid isocyanate compound shown in formula three, and then purifying and drying.

[0018] As a technical scheme of the present application, the first solvent includes at least one of nitrile solvent, halogenated hydrocarbon solvent, ether solvent, ester solvent, ketone solvent and aromatic hydrocarbon solvent.

[0019] As a technical scheme of the present application, the temperature during mixing in step (1) is -40-50℃, and the time is 15-60h.

[0020] As a technical scheme of the present application, the reaction temperature in step (2) is -20-10℃, and the reaction time is 1-24h.

[0021] As a technical scheme of the present application, the molar ratio of the compound shown in formula three and the compound shown in formula two is 1:1.0-1.2.

[0022] As a technical scheme of the present application, the purification is filtration or washing, and the drying condition is vacuum drying at 35-120 DEG C for 1-24h.

[0023] The third aspect of the present application provides application of the imidazole zwitterionic compound in secondary batteries. DETAILED DESCRIPTION

[0024] The imidazole zwitterionic compound of the present application can be used as an intermediate for material synthesis or in batteries.

[0025] The structural formula of the imidazole zwitterionic compound of the present application is shown in formula one.

[0026]

[0027] R1is halogen, aryl or halogen substituted aryl, more preferably, R1is fluorine, chlorine, bromine, phenyl, tolyl, ethylphenyl, fluorophenyl, fluorotolyl, fluoroethylphenyl. More preferably, R1is fluorine, chlorine, phenyl, tolyl. R2, R3, R4and R5are each independently selected from H, halogen, CN, NO2, NH2, OH, COOH, SO2F, C1-C4alkyl, halogen substituted C1-C4alkyl. More preferably, R2, R3, R4and R5are each independently selected from H, fluorine, chlorine, bromine, CN, NH2, OH, COOH, SO2F, methyl, ethyl, propyl, isopropyl, butyl, fluoromethyl, fluoroethyl, fluoropropyl, fluoroisopropyl, fluorobutyl, difluoromethyl, difluoroethyl, difluoropropyl, difluoroisopropyl, difluorobutyl, ethenyl, propenyl, isopropenyl, butenyl, fluoromethenyl, fluoroethenyl, fluoropropenyl, fluoroisopropenyl, fluorobutenyl, difluoromethenyl, difluoroethenyl, difluoropropenyl, difluoroisopropenyl, difluorobutenyl. ethynyl, propynyl, isopropynyl, butynyl, fluoromethynyl, fluoroethynyl, fluoropropynyl, fluoroisopropynyl, fluorobutynyl, difluoromethynyl, difluoroethynyl, difluoropropynyl, difluoroisopropynyl, difluorobutynyl. chloromethyl, chloroethyl, chloropropyl, chloroisopropyl, chlorobutyl, dichloromethyl, dichloroethyl, dichloropropyl, dichloroisopropyl, dichlorobutyl, chloromethenyl, chloroethenyl, chloropropenyl, chloroisopropenyl, chlorobutenyl, dichloromethenyl, dichloroethenyl, dichloropropenyl, dichloroisopropenyl, dichlorobutenyl. Further, R2, R3, R4and R5are each independently selected from H, fluorine, bromine, CN, methyl, ethyl, propyl, isopropyl, butyl, fluoromethyl, fluoroethyl, fluoropropyl, fluoroisopropyl, fluorobutyl, difluoromethyl, difluoroethyl, difluoropropyl, difluoroisopropyl, difluorobutyl, etc.

[0028] Further, the imidazolium zwitterionic compound includes at least one of compound one to compound seven. Of course, the imidazolium zwitterionic compound can be other compounds, at least it meets the structure shown in formula one

[0029]

[0030] The preparation method of the imidazolium zwitterionic compound of the present application can include the following steps.

[0031] (1) mixing the compound shown in formula three and the first solvent to form a first solution.

[0032] (2) The first solution and the second solution are mixed dropwise and reacted under heating to obtain a primary product, the second solution being a salt solution, the salt solution being a mixed solution of a tetrafluoroborate salt and the first solvent or a mixed solution of a hexafluorophosphate salt and the first solvent.

[0033] (3) The primary product is purified and dried.

[0034] wherein R2, R3, R4and R5are each independently selected from H, halogen, CN, NO2, NH2, OH, COOH, SO2F, C1-C4 hydrocarbon group, halogen-substituted C1-C4 hydrocarbon group, R1is halogen, aromatic group or halogen-substituted aromatic group.

[0035]

[0036] The imidazole compound shown in formula II can be obtained by market purchase or by substituting the substituent group through the reaction of the market-purchased substance. The imidazole compound can be N-methyl imidazole, 1,4-dimethyl-1H-imidazole, 1-methyl-4-fluoro-1H-imidazole, 1-methyl-1H-imidazole-4-carbonitrile.

[0037] The sulfonic acid isocyanate compound shown in formula III can be chlorosulfonic acid isocyanate directly purchased or fluorosulfonic acid isocyanate obtained by replacing the chlorine in chlorosulfonic acid isocyanate. Specifically, anhydrous potassium fluoride is heated to a certain temperature, chlorosulfonic acid isocyanate is added dropwise under stirring with condensation reflux, after the dropwise addition is completed, the reaction is carried out at 100-160°C for 3-10h, after the reaction is completed, the fluorosulfonic acid isocyanate is obtained by normal pressure distillation and collection of the fraction in sequence. The temperature for normal pressure distillation is 100°C, and the temperature interval for collection of the fraction is 65-100°C. The tosylsulfonic acid isocyanate can be prepared by reacting p-toluenesulfonamide with triphosgene.

[0038] The first solvent includes at least one of nitrile solvents, halogenated hydrocarbon solvents, ether solvents, ester solvents, ketone solvents and aromatic hydrocarbon solvents. Specifically, the nitrile solvent is acetonitrile or butyronitrile, the halogenated hydrocarbon solvent is dichloromethane, trichloromethane, 1,2 dichloroethane or tetrachloroethane, the ether solvent is methyl tert-butyl ether, ethylene glycol dimethyl ether, tetrahydrofuran or dioxane, the ester solvent is dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl acetate, ethyl acetate or propyl acetate, the ketone solvent is acetone, cyclohexanone or 4-methyl-2-pentanone, and the aromatic hydrocarbon solvent is benzene, toluene or xylene. Preferably, the first solvent is at least one of acetonitrile and dimethyl carbonate.

[0039] The temperature during mixing is about 40-50°C, further, the temperature during mixing is -10-10°C. As an example, the temperature can be, but is not limited to, -40°C, -35°C, -30°C, -25°C, -20°C, -15°C, -10°C, -5°C, 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C. The time is 15-60h, as an example, the time can be, but is not limited to, 15h, 20h, 25h, 30h, 35h, 40h, 45h, 50h, 55h, 60h.

[0040] The reaction temperature of step (2) is -20-10°C, as an example, the reaction temperature can be, but is not limited to, -20°C, -15°C, -10°C, -5°C, 0°C, 5°C, 10°C. The reaction time is 1-24h, preferably, the reaction time is 6-12h, as an example, the time can be, but is not limited to, 6h, 7h, 8h, 9h, 10h, 11h, 12h. The molar ratio of the compound of formula III to the compound of formula II is 1:1.0-1.2, as an example, the molar ratio can be, but is not limited to, 1:1.0, 1:1.1, 1:1.2. Preferably, the molar ratio of the compound of formula III to the salt solution is 1:1.

[0041] The purification in step (3) is filtration or washing, and the washing is carried out using a polar solvent / weak polar solvent. The polar solvent includes acetonitrile, acetone, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethyl acetate, propyl acetate, butyl acetate, diethyl ether, methyl tert-butyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, dioxane. The weak polar solvent includes dichloromethane, trichloromethane, n-hexane, cyclohexane, toluene, xylene, chlorobenzene, fluorobenzene. The drying condition is vacuum drying at 35-120°C for 1-24h, and the temperature of vacuum drying can be, but is not limited to, 35°C, 45°C, 55°C, 65°C, 75°C, 85°C, 95°C, 105°C, 115°C, 120°C. The drying time can be, but is not limited to, 1h, 3h, 5h, 7h, 9h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h.

[0042] 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.

[0043] First part: preparation of the sulfonic acid isocyanate compound of formula III

[0044] Example 1

[0045] This example is to prepare fluorosulfonic acid isocyanate, and the preparation method comprises the following steps.

[0046] Put 68.0 g of anhydrous potassium fluoride into a multi-neck flask equipped with a speed-regulated stirrer, a condensing reflux tube, and a constant-pressure dropping funnel. Start stirring, and then place the multi-neck flask in a water bath. Control the temperature of the water bath at 100°C, and the temperature of the cold water in the condensing reflux tube at -20°C. Slowly drop 141.5 g of chlorosulfonic acid isocyanate into the multi-neck flask using the constant-pressure dropping funnel. After the dropping is completed, control the temperature of the water bath at 130°C, and reflux for 6 h. After the reaction is completed, perform normal-pressure distillation at 100°C, and collect the distillate in the temperature range of 65-100°C to obtain 106.0 g of fluorosulfonic acid isocyanate, with a yield of 85.0% and a purity of 99.0%.1H NMR (400 MHz, CD3CN): 0.0 1F, indicating that fluorosulfonic acid isocyanate is synthesized. 19 F-NMR (CD3CN): 0.0 1F, indicating that fluorosulfonic acid isocyanate is synthesized.

[0047] The preparation reaction equation of fluorosulfonic acid isocyanate is shown below.

[0048]

[0049] Example 2

[0050] This example is for the preparation of tosyl isocyanate. The preparation method comprises the following steps.

[0051] Dissolve 86.04 g of p-toluenesulfonamide and 86 g of chlorobenzene to obtain a toluenesulfonamide chlorobenzene solution, and then add the solution into a constant-pressure dropping funnel. Add 148 g of triphosgene into 100 g of chlorobenzene, and then mix uniformly. After the toluenesulfonamide chlorobenzene solution is added into a reaction flask, stir and heat to above 90°C, and then control the temperature at 105°C for 4 h. After the reaction is completed, connect a condenser tube and a receiving bottle, and then start recovering the solvent chlorobenzene. Control the vacuum degree at -0.08 Mpa, and the recovery temperature at 105°C. After the recovery of the solvent chlorobenzene is completed, transfer the material into a distillation flask, connect a vacuum pump to vacuumize to below -0.095 Mpa, and then heat to obtain 97.73 g of p-toluenesulfonyl isocyanate, with a detection content of 99.19% and an experimental yield of 98.33%.1H NMR (400 MHz, CD3CN): 2.43 (s, 3H), 7.43-7.44 (d, 2H), 7.46-7.47 (d, 2H), indicating that tosyl isocyanate is synthesized.

[0052] The preparation reaction equation of tosyl isocyanate is shown below.

[0053]

[0054] Second Part: Preparation of Imidazole Zwitterionic Compounds

[0055] Example 3

[0056] This example is for preparing compound one, and the preparation method comprises the following steps.

[0057] (1) 16.6 g of N-methyl imidazole and 80.0 g of dichloromethane were stirred at 0°C for 10 min to form a first solution.

[0058] (2) The second solution was added dropwise to the first solution at 0°C for 20 h to obtain a primary product, and the second solution was formed by uniformly mixing 28.6 g of chlorosulfonic acid isocyanate and 80.0 g of dichloromethane.

[0059] (3) The primary product was filtered, washed with dichloromethane, and dried at 60°C under vacuum to obtain 41.5 g of compound one, with a yield of 92.0% and a purity of 99.0%, and the hydrogen spectrum: 1H NMR (400 MHz, CD3CN): 3.60 (s, 3H), 6.60 (s, 1H), 7.10 (t, 1H), 7.60 (t, 1H), indicating that compound one was synthesized.

[0060]

[0061] The preparation reaction equation of compound one of this example is shown below.

[0062] Example 4

[0063] This example is for preparing compound two, and the preparation method comprises the following steps.

[0064] (1) 16.6 g of N-methyl imidazole and 80.0 g of dichloromethane were stirred at 0°C for 10 min to form a first solution.

[0065] (2) The second solution was added dropwise to the first solution at 0°C for 20 h to obtain a primary product, and the second solution was formed by uniformly mixing 28.6 g of chlorosulfonic acid isocyanate and 80.0 g of dichloromethane.

[0066] (3) The primary product was filtered, washed with dichloromethane, and dried at 60°C under vacuum to obtain 41.5 g of compound one, with a yield of 92.0% and a purity of 99.0%, and the hydrogen spectrum: 1H NMR (400 MHz, CD3CN): 3.60 (s, 3H), 6.60 (s, 1H), 7.10 (t, 1H), 7.60 (t, 1H), indicating that compound one was synthesized. 19 F-NMR (CD3CN): 61.01F, indicating that compound two was synthesized.

[0067]

[0068] The preparation reaction equation of compound two of this example is shown below.

[0069] Example 5

[0070] This example is for preparing compound three, the preparation method of which comprises the following steps.

[0071] (1) Forming a first solution by stirring 19.4 g of 1,4-dimethyl-1H-imidazole and 80.0 g of dichloromethane at 0°C for 10 min.

[0072] (2) Dropping a second solution into the first solution at 0°C for 20 h to obtain a primary product, the second solution being formed by uniformly mixing 28.6 g of chlorosulfonic acid isocyanate and 80.0 g of dichloromethane.

[0073] (3) Filtering the primary product, washing with dichloromethane, and vacuum drying at 70°C to obtain 44.9 g of compound three, with a yield of 93.5% and a purity of 99.0%, and the hydrogen spectrum:1H NMR (400 MHz, CD3CN): 1.60 (s, 3H), 3.60 (s, 3H), 6.54 (s, 1H), 6.90 (s, 1H), indicating that compound three is synthesized.

[0074]

[0075] The preparation reaction equation of compound three of this example is shown below.

[0076] Example 6

[0077] This example is for preparing compound four, the preparation method of which comprises the following steps.

[0078] (1) Forming a first solution by stirring 19.4 g of 1,4-dimethyl-1H-imidazole and 80.0 g of dichloromethane at 0°C for 10 min.

[0079] (2) Dropping a second solution into the first solution at 0°C for 16 h to obtain a primary product, the second solution being formed by uniformly mixing 25.3 g of fluorosulfonic acid isocyanate prepared in Example 1 and 80.0 g of dichloromethane.

[0080] (3) Filtering the primary product, washing with dichloromethane, and vacuum drying at 60°C to obtain 43.4 g of compound four, with a yield of 97.0% and a purity of 99.0%, and the hydrogen spectrum:1H NMR (400 MHz, CD3CN): 1.34 (s, 3H), 3.70 (s, 3H), 6.56 (s, 1H), 7.0 (s, 1H), 19 F-NMR (CD3CN): 61.51F, indicating that compound four is synthesized.

[0081] The preparation reaction equation of compound four of this example is shown below.

[0082] Example 7

[0083] This example is to prepare compound five, and the preparation method comprises the following steps.

[0084] (1) 20.0 g of 1-methyl-4-fluoro-1H-imidazole and 80 g of dichloromethane were stirred at 0°C for 10 min to form a first solution.

[0085] (2) The second solution was added dropwise to the first solution at 0°C for 16 h to obtain a primary product, and the second solution was uniformly mixed by 25.3 g of isocyanate fluoride prepared in Example 1 and 80 g of dichloromethane.

[0086] (3) The primary product was filtered, washed with dichloromethane, and dried at 70°C under vacuum to obtain 43.5 g of compound five, with a yield of 95.5% and a purity of 99.0%, and the hydrogen spectrum was: 1H NMR (400 MHz, CD3CN): 3.70 (s, 3H), 6.58 (s, 1H), 7.2 (s, 1H), 19 F-NMR (CD3CN): 41.51 F, 61.51 F, indicating that compound five was synthesized.

[0087]

[0088] The preparation reaction equation of compound five in this example is shown in the following.

[0089] Example 8

[0090] This example is to prepare compound six, and the preparation method comprises the following steps.

[0091] (1) 21.6 g of 1-methyl-1H-imidazole-4-carbonitrile and 80 g of toluene were stirred at -2°C for 15 min to form a first solution.

[0092] (2) The second solution was added dropwise to the first solution at -2°C for 20 h to obtain a primary product, and the second solution was uniformly mixed by 25.3 g of isocyanate fluoride prepared in Example 1 and 80 g of toluene.

[0093]

[0094]

[0095] (3) The primary product was filtered, washed with toluene, and dried at 100°C under vacuum to obtain 43.4 g of compound six, with a yield of 92.3% and a purity of 99.0%, and the hydrogen spectrum was: 1H NMR (400 MHz, CD3CN): 3.40 (s, 3H), 6.43 (s, 1H), 7.4 (s, 1H), 19F-NMR (CD3CN): 61.51 F, indicating that compound six was synthesized.

[0096] The reaction equation for preparing compound six of this example is shown below.

[0097] Example 9

[0098] This example is for preparing compound seven, and the preparation method comprises the following steps.

[0099] (1) 16.6 g of N-methyl imidazole and 80 g of toluene were stirred at 0°C for 10 min to form a first solution.

[0100] (2) The second solution was added dropwise to the first solution at 0°C for 20 h to obtain a primary product, and the second solution was prepared by mixing 39.9 g of p-toluenesulfonic acid isocyanate prepared in Example 2 and 80 g of toluene uniformly.

[0101] The second solution was prepared by mixing 39.9 g of p-toluenesulfonic acid isocyanate prepared in Example 2 and 80 g of toluene uniformly.

[0102] (3) The primary product was filtered, washed with toluene, and vacuum dried at 100°C to obtain 54.3 g of compound seven, with a yield of 96.0% and a purity of 99%, and the hydrogen spectrum was 1H NMR (400 MHz, CD3CN): 2.40 (s, 3H), 3.40 (s, 3H), 7.1 (t, 7H), indicating that compound seven was synthesized.

[0103] The reaction equation for preparing compound seven of this example is shown below.

[0104] Part III: Application of imidazole-based zwitterionic compounds in secondary batteries

[0105] 1.5 g of compounds one to seven prepared in Examples 3-9 and 86.0 g of non-aqueous organic solvent (vinyl carbonate EC, diethyl carbonate DEC, and methyl ethyl carbonate EMC in a mass ratio of 3:2:1) were mixed uniformly, and then 12.5 g of lithium hexafluorophosphate LiPF6 was added and mixed uniformly to prepare non-aqueous electrolyte 1#-7#.

[0106] 87.5 g of non-aqueous organic solvent (vinyl carbonate EC, diethyl carbonate DEC, and methyl ethyl carbonate EMC in a mass ratio of 3:2:1) and 12.5 g of lithium hexafluorophosphate LiPF6 were mixed uniformly to prepare non-aqueous electrolyte 8#.

[0107] Lithium cobaltate was used as the positive electrode material and lithium metal as the counter electrode, and non-aqueous electrolyte 1#-8# was injected to assemble button cells 1#-8# respectively. Under normal temperature (25℃) conditions, the button cells were charged and discharged at 4.0C / 4.0C (the battery discharge capacity was recorded as C0) for one time, the upper limit voltage was 4.1V, then charged and discharged at 4.0C / 4.0C for 200 cycles, and the capacity retention rate was calculated.

[0108] Capacity retention rate = (battery capacity C1 after 200 cycles / initial battery capacity C0) * 100%

[0109] Table 1: electrochemical performance test results of each example

[0110]

[0111] From the results in Table 1, it can be seen that the cycle performance of button cells 1-7# is better than that of button cell 8#, which is because the electrolyte of button cells 1-7# contains imidazole zwitterionic compounds, which has the advantages of both ionic liquids and sulfonimide groups, and can improve the conductivity of the material, thus improving the cycle performance of the battery at high rate.

[0112] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not intended 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, it is not limited to the examples listed in the embodiments. 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 present application.

Claims

1. An imidazole zwitterionic compound, characterized in that, The structural formula is shown in Formula 1, where R1 is a halogen, and R2, R3, R4, and R5 are each independently selected from H, halogens, CN, NO2, NH2, OH, COOH, SO2F, C1-C4 alkyl groups, and halogen-substituted C1-C4 alkyl groups.

2. The imidazole zwitterionic compound according to claim 1, characterized in that, R1 is fluorine, chlorine, and R2, R3, R4 and R5 are each independently selected from H, fluorine, chlorine, CN, NO2, NH2, OH, COOH, C1 to C4 alkyl groups, and halogen-substituted C1 to C4 alkyl groups.

3. An imidazole zwitterionic compound, characterized in that, Selected from at least one of compounds one through seven, 4. The method for preparing imidazole zwitterionic compounds according to claim 1, characterized in that, Including the following steps: (1) Mix the compound shown in Formula 2 with the first solvent to form a first solution; (2) The first solution and the second solution are added dropwise and mixed and reacted to obtain a primary product. The second solution is a mixture of a sulfonic acid isocyanate compound as shown in Formula 3 and the first solvent. (3) The primary product is purified and dried. R2, R3, R4 and R5 are each independently selected from H, halogen, CN, NO2, NH2, OH, COOH, SO2F, C1 to C4 alkyl groups, halogen-substituted C1 to C4 alkyl groups, and R1 is a halogen.

5. The method for preparing imidazole zwitterionic compounds according to claim 4, characterized in that, 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.

6. The method for preparing imidazole zwitterionic compounds according to claim 4, characterized in that, The mixing temperature in step (1) is -40 to 50°C, and the time is 15 to 60 hours.

7. The method for preparing imidazole zwitterionic compounds according to claim 4, characterized in that, The reaction temperature in step (2) is -20 to 10°C, and the reaction time is 1 to 24 hours.

8. The method for preparing imidazole zwitterionic compounds according to claim 4, characterized in that, The molar ratio of the compound shown in Formula 3 to the compound shown in Formula 2 is 1:1.0 to 1.

2.

9. The method for preparing imidazole zwitterionic compounds according to claim 4, characterized in that, The purification process involves filtration or washing, and the drying conditions are vacuum drying at 35–120°C for 1–24 hours.

10. The application of the imidazole zwitterionic compound according to any one of claims 1 to 3, characterized in that, Used in secondary batteries.

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