Cyclic sulfate solution as well as preparation method and application thereof

Abstract

The invention provides a cyclic sulfate solution as well as a preparation method and application thereof. The cyclic sulfate solution comprises a cyclic sulfate compound, a color blocking agent and an organic solvent, the color blocking agent comprises a compound containing metal cations, and the metal cations comprise at least one of tungsten cations, molybdenum cations, nickel cations, cobalt cations, vanadium cations, niobium cations, titanium cations, manganese cations, ruthenium cations, platinum cations and palladium cations. According to the cyclic sulfate solution disclosed by the invention, by adding the color blocking agent, the color change problem of the cyclic sulfate solution can be improved, and the quality risk is avoided while the product solubilization is realized.

Description

Technical Field

[0001] The present application relates to the technical field of secondary batteries, and in particular to a cyclic sulfate solution and a preparation method and application thereof. Background Art

[0002] At present, the application of secondary batteries is developing rapidly in various fields, and electrolyte additives used in secondary battery electrolytes are also being updated. Among them, cyclic sulfate compounds are widely used as electrolyte additives due to their excellent performance. However, cyclic sulfate compounds are unstable to water and produce fuming sulfuric acid, which is corrosive. Direct storage and transportation are highly harmful to personnel and equipment, and there is a problem of discoloration when prepared into solutions. Solutions containing cyclic sulfate compounds quickly change from colorless and transparent to yellow-red or yellow-brown in a few days to weeks, posing a challenge to product quality.

[0003] Therefore, there is an urgent need to develop a cyclic sulfate solution that is less likely to change color and thus has better storage performance. Summary of the invention

[0004] In view of this, an object of the present application is to provide a cyclic sulfate solution. Adding a color inhibitor to the cyclic sulfate compound solution system can improve the discoloration problem of the cyclic sulfate solution, thereby achieving product solubilization and avoiding quality risks.

[0005] Another object of the present application is to provide a method for preparing a cyclic sulfate solution.

[0006] Another object of the present application is to provide an electrolyte.

[0007] Another object of the present application is to provide a secondary battery.

[0008] To achieve the above-mentioned purpose, the first aspect of the present application proposes a cyclic sulfate solution, comprising a cyclic sulfate compound, a color inhibitor and an organic solvent; the color inhibitor comprises a compound containing metal cations, and the metal cations include at least one of tungsten cations, molybdenum cations, nickel cations, cobalt cations, vanadium cations, niobium cations, titanium cations, manganese cations, ruthenium cations, platinum cations and palladium cations.

[0009] In some embodiments, the cyclic sulfate ester compound includes a compound having a structure of Formula 1:

[0010]

[0011] In Formula 1, R1, R2, and R5 are each independently selected from One of, and at least one of R1, R2, R5 is R3 and R4 are each independently selected from one of H, a halogen atom, a C1-C5 halogenated hydrocarbon group or a C1-C5 hydrocarbon group, m and n are both integers of 0-3, and m and n are not 0 at the same time.

[0012] In some embodiments, both m and n are 1.

[0013] In some embodiments, the R3 and R4 are each independently selected from H or a halogen atom.

[0014] In some embodiments, the cyclic sulfate ester compound having the structure of Formula 1 includes at least one of compounds 1-6:

[0015]

[0016] In some embodiments, the metal cation includes at least one of a ruthenium cation, a manganese cation, a titanium cation, and a tungsten cation.

[0017] In some embodiments, the compound containing metal cations includes at least one of metal salts, metal coordination compounds, and metal complexes, and the anions in the metal salts preferably include at least one of fluoride ions, sulfate ions, chloride ions, and bromide ions, and more preferably fluoride ions.

[0018] In some embodiments, the mass content of the metal cation in the cyclic sulfate solution is 1-1000 ppm, for example, greater than 1 ppm and less than 100 ppm.

[0019] In some embodiments, based on the total mass of the cyclic sulfate solution as 100%, the mass content of the cyclic sulfate compound represented by the structural formula I in the cyclic sulfate solution is 0.01% to 60%, preferably 15-45%, and more preferably 25-35%.

[0020] In some embodiments, the organic solvent includes at least one of an ether solvent, a nitrile solvent, a carbonate solvent, a carboxylate solvent, and a sulfone solvent.

[0021] In some embodiments, the ether solvent includes at least one of a cyclic ether and a chain ether.

[0022] In some embodiments, the nitrile solvent includes at least one of acetonitrile, glutaronitrile, and malononitrile.

[0023] In some embodiments, the carbonate solvent includes at least one of a cyclic carbonate and a linear carbonate.

[0024] In some embodiments, the carboxylate solvent includes at least one of methyl acetate (MA), ethyl acetate (EA), propyl acetate (EP), butyl acetate, propyl propionate (PP), and butyl propionate.

[0025] In some embodiments, the sulfone solvent includes at least one of sulfolane and dimethyl sulfoxide.

[0026] In some embodiments, the cyclic sulfate ester solution consists of the cyclic sulfate ester compound, the color inhibitor and the solvent.

[0027] The second aspect of the present application provides a method for preparing the cyclic sulfate solution, comprising:

[0028] Adding the color inhibitor to part of the organic solvent to obtain a first mixed solution;

[0029] Using another portion of the organic solvent to grade-dilute the first mixed solution to obtain a second mixed solution;

[0030] The cyclic sulfate is added into the second mixed solution and mixed to obtain the solution.

[0031] A third aspect of the present application provides an electrolyte, comprising the cyclic sulfate ester solution described in the present application or a cyclic sulfate ester solution prepared by the preparation method of the cyclic sulfate ester solution described in the present application.

[0032] In some embodiments, the mass content of the cyclic sulfate ester solution in the electrolyte is 5-60%.

[0033] A fourth aspect of the present application provides a secondary battery, comprising a positive electrode, a negative electrode, a separator and an electrolyte, wherein the electrolyte is the electrolyte described in the present application.

[0034] The cyclic sulfate solution described in the present application can at least bring the following beneficial effects:

[0035] By adding a color inhibitor, the discoloration problem of the cyclic sulfate solution during storage can be greatly improved at a relatively low cost. This may be attributed to the fact that the color inhibitor can prevent the transfer, transition and conjugation of the cyclic sulfate electrons in the solution, inhibit the formation of auxochromes with a dark effect, and prevent the color from further deepening. Therefore, the cyclic sulfate solution with the addition of the color inhibitor has better color stability during storage, and improves the environmental adaptability of the cyclic sulfate solution.

[0036] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. DETAILED DESCRIPTION

[0037] The following embodiments of the present application are described in detail. The following embodiments are exemplary and intended to be used to explain the present application, but should not be construed as limiting the present application.

[0038] In this application, the disclosure of numerical ranges includes all values ​​within the entire range and the disclosure of further subdivided ranges, including the endpoints and sub-ranges given in these ranges.

[0039] In this application, the raw materials, equipment, etc. involved, unless otherwise specified, are all raw materials and equipment that can be made through commercial channels or known methods; the methods involved, unless otherwise specified, are all conventional methods.

[0040] As used herein, the following terms have the indicated meanings.

[0041] The term "and / or", when used in a list of two or more items, means that any of the listed items can be used alone or in combination with any one or more of the listed items. For example, the expression "A and / or B" is intended to mean A or B or A and B, that is, only A, only B, or a combination of A and B.

[0042] The term "hydrocarbon group" refers to a group containing only carbon and hydrogen atoms, generally referring to the group remaining after the corresponding hydrocarbon (e.g., alkane, alkene, alkyne, cycloalkane) loses a hydrogen atom (H), such as alkyl, alkenyl, alkynyl, cycloalkyl, etc.

[0043] The term "haloalkyl" refers to an alkyl group having the meaning defined above wherein one or more hydrogens are replaced by a halogen. Specifically contemplated are monohaloalkyl, dihaloalkyl and polyhaloalkyl groups.

[0044] The inventors found that the discoloration and deepening of the cyclic sulfate solution are mainly due to the transfer, transition and conjugation of the cyclic sulfate electrons in the solution, which causes the auxochromophore with a dark effect to red-shift the wavelength band of light absorption, resulting in the discoloration and deepening of the solution color. Therefore, it is necessary to find a color inhibitor that meets the following conditions: there is enough absorption band in the visible light region; the color must be reversible and have no side reactions; the potential is suitable and can play a role in the storage of cyclic sulfate solutions. Based on the above, the inventors found that compounds containing metal cations can be used as color inhibitors, and they can significantly improve the chromaticity problem of cyclic sulfate solutions during storage at a relatively small addition amount.

[0045] The cyclic sulfate ester solution and the preparation method of the cyclic sulfate ester solution according to the embodiments of the present application are described in detail below.

[0046] <Cyclic Sulfate Ester Solution>

[0047] The cyclic sulfate solution of the embodiment of the present application includes a cyclic sulfate compound, a color inhibitor and an organic solvent; the color inhibitor includes a compound containing metal cations, and the metal cations include at least one of tungsten (W) cations, molybdenum (Mo) cations, nickel (Ni) cations, cobalt (Co) cations, vanadium (V) cations, niobium (Nb) cations, titanium (Ti) cations, manganese (Mn) cations, ruthenium (Ru) cations, platinum (Pt) cations, and palladium (Pd) cations.

[0048] It is understandable that in the embodiments of the present application, there is no limitation on the specific selection of the cyclic sulfate ester compound, which may be any compound belonging to the cyclic sulfate ester compound, preferably a cyclic sulfate ester compound that can be used as a secondary battery electrolyte additive.

[0049] As an optional example, the cyclic sulfate ester compound includes a compound having a structure of Formula 1:

[0050]

[0051] In Formula 1, R1, R2, and R5 are each independently selected from One of, and at least one of R1, R2, R5 is R3 and R4 are each independently selected from one of H, a halogen atom, a C1-C5 halogenated hydrocarbon group or a C1-C5 hydrocarbon group, m and n are both integers of 0-3, and m and n are not 0 at the same time.

[0052] In some embodiments, the halogen atom includes a fluorine atom (F), a chlorine atom (Cl), a bromine atom (Br), or an iodine atom (I).

[0053] In some embodiments, the number of carbon atoms in the C1-C5 halogenated hydrocarbon group and the C1-C5 hydrocarbon group can be 1, 2, 3, 4 or 5. The hydrocarbon group includes an alkane group, an alkene group, an alkyne group or a cycloalkyl group, and the halogen atom in the halogenated hydrocarbon group can be a fluorine atom (F), a chlorine atom (Cl), a bromine atom (Br) or an iodine atom (I).

[0054] Exemplary C1-C5 hydrocarbon groups include, but are not limited to, methyl (-CH3), ethyl (-C2H5), n-propyl (-CH2CH2CH3), isopropyl (-CH(CH3)2), cyclopropyl n-Butyl (-CH2CH2CH2CH3), isobutyl (-CH(CH3)CH2CH3), sec-butyl (-CH2CH(CH3)2), tert-butyl (-C(CH3)3), cyclobutyl -CH2CH2CH2CH2CH3, -CH(CH3)CH2CH2CH3, -CH2CH(CH3)CH2CH3, -CH2CH2CH(CH3)2, -CH(C2H5)CH2CH3, -C(CH3)2CH2CH3, -CH(CH3)CH(CH3)2, -CH2C(CH3)3, cyclopentyl Vinyl (-CH=CH2), propenyl (-CH=CH-CH3), -CH=CH2-CH2-CH3, -CH=CH2-CH=CH2, Ethyl (-C≡CH) or propynyl (-C≡C-CH3), etc.

[0055] Exemplarily, the C1-C5 halogenated hydrocarbon group is a hydrocarbon group in which one or more H atoms in the above C1-C5 hydrocarbon group are substituted by a halogen atom, for example: fluoromethyl, difluoromethyl, trifluoromethyl, chloromethyl, dichloromethyl, trichloromethyl, pentafluoroethyl, heptafluoropropyl, difluorochloromethyl, dichlorofluoromethyl, difluoroethyl, difluoropropyl, dichloroethyl or dichloropropyl, etc.

[0056] In some embodiments, the value of m is 0, 1, 2 or 3, the value of n is 0, 1, 2 or 3, and m and n are not 0 at the same time.

[0057] As an optional example, both m and n are 1.

[0058] As an optional example, the R3 and the R4 are each independently selected from one of H or a halogen atom.

[0059] Preferably, the cyclic sulfate ester compound having the structure of Formula 1 includes at least one of compounds 1-6:

[0060]

[0061] It should be noted that the above compounds are only preferred compounds of the cyclic sulfate ester compounds having the structure of Formula 1, and are not intended to limit the present application.

[0062] In some embodiments, the cyclic sulfate compound having the structural formula 1 can be obtained by the following preparation method: 1 mol of polyol (for example, at least one of sorbitol, mannitol, galactitol, sorbitol chloride, etc.), 2-5 mol of carbonate (for example, at least one of dimethyl carbonate, diethyl carbonate, diphenyl carbonate, etc.), alkaline catalyst (for example, at least one of potassium carbonate, sodium methoxide, sodium bicarbonate, etc.) and 1-10 mol of organic solvent (for example, at least one of DMF, EMC, DMSO, methanol, etc.) are placed in a reaction vessel, and a condensed water reflux device and a mechanical stirring device are set up at the same time, and the reaction is carried out under high temperature conditions of 70-90°C. The reaction is carried out at high temperature for 5-8h, and the TLC spot plate is monitored. At this time, the reaction is continued at 30-50°C for 10-16h, and then a certain amount of oxalic acid is added to adjust the pH to neutral, the salt generated by the acid-base neutralization reaction is filtered out, and the remaining solution is concentrated under reduced pressure. The concentrated solid is dissolved in ethyl acetate / ethanol and recrystallized to obtain the intermediate product 1. Then, 1 mol of the intermediate product 1, 2-10 mol of carbonate (for example, at least one of dimethyl carbonate, diethyl carbonate, etc.), 2-5 mol of dichlorothionyl, 0.01-0.5 mol of catalyst (DMF, DME, etc.) are placed in a new reaction container, and an esterification reaction is carried out under high temperature conditions of 40-80°C to obtain an intermediate product 2. Then, 2-3 mol of an oxidant such as sodium periodate is used to oxidize the intermediate product 2 (the reaction temperature is -10°C to -25°C, and the reaction time is 4-8h) to obtain a compound having the structural formula 1.

[0063] In other embodiments, the cyclic sulfate compound having the structural formula 1 can be obtained by the following preparation method: 1 mol of a polyol (at least one of sorbitol, mannitol, galactitol, sorbitol chloride, etc.), a catalyst (for example, at least one of potassium iodide and sodium iodide) and 1-10 mol of an organic solvent (for example, at least one of DMF, EMC, DMSO, methanol, etc.) are placed in a reaction vessel, and a condensed water reflux device and a mechanical stirring device are set up at the same time. The reaction is carried out under high temperature conditions of 70-90°C, chlorine gas is introduced under stirring, the reaction is carried out for 1-5 hours, and the reaction is terminated in time by TLC spot plate monitoring, and then a certain amount of sodium bicarbonate is added to adjust the pH to neutral, the salt generated by the acid-base neutralization reaction is filtered out, and the remaining solution is concentrated under reduced pressure, and the concentrated solid is dissolved in ethyl acetate / ethanol and recrystallized to obtain the intermediate product 1. Then, 1 mol of intermediate 1, 2-10 mol of dimethoxypropane and a catalyst (for example, at least one of sodium bicarbonate, triethylamine, sodium carbonate, etc.) are placed in a reaction vessel and reacted at 10-25° C. for 6-12 hours to obtain intermediate 2; 1 mol of intermediate 2, 2-5 mol of sodium bisulfite, and 1-10 mol of an organic solvent (for example, at least one of DMF, EMC, DMSO, methanol, etc.) are placed in a reaction vessel, and a condensed water reflux device and a mechanical stirring device are set up at the same time, and the reaction is carried out at a high temperature of 70-90° C. for 2-6 hours. , then add sulfuric acid, concentrate at 110 degrees Celsius for 4 hours, wash with carbonate solvents, and concentrate the solution to obtain intermediate 3; add pure water, carbonate and other solvents to intermediate 3, then add acid to adjust the reaction solution to acidity (pH 6-7) and hydrolyze at 5-10°C for 1-4 hours to obtain intermediate 4; 1 mol of intermediate, 2 mol of dimethyl carbonate, alkaline substance catalyst potassium carbonate and 8 mol of organic solvent methanol are placed in a reaction vessel, and a condensed water reflux device and a mechanical stirring device are set up at the same time, and the reaction is carried out under high temperature conditions of 70-90°C. React at high temperature for 5-8 hours, monitor with TLC spot plate, continue to heat at 30-50°C for 10-16 hours, then add a certain amount of oxalic acid to adjust the pH to neutral, filter out the salt generated by the acid-base neutralization reaction and concentrate the remaining solution under reduced pressure, and dissolve the concentrated solid in ethyl acetate / ethanol and recrystallize to obtain intermediate 5. Then, 1 mol of the intermediate product 5, 2-10 mol of carbonate (for example, at least one of dimethyl carbonate, diethyl carbonate, etc.), 2-3 mol of dichlorothionyl, 0.01-0.5 mol of catalyst (DMF, DME, etc.) are placed in a new reaction container, and an esterification reaction is carried out under high temperature conditions of 40-80°C to obtain the intermediate product 6. Then, 2-3 mol of an oxidant such as sodium periodate is used to oxidize the intermediate product 6 (the reaction temperature is -10-25°C, and the reaction time is 4-8h) to obtain a compound 5 having the structural formula 1.

[0064] In some other embodiments, the cyclic sulfate compound having the structural formula 1 can be obtained by the following preparation method: 1 mol of a polyol (for example, at least one of sorbitol, mannitol, galactitol, sorbitol chloride, etc.) and 2-10 mol of dimethoxypropane and a catalyst (for example, at least one of sodium bicarbonate, triethylamine, sodium carbonate, etc.) are placed in a reaction vessel and reacted at 10-25° C. for 6-12 hours to obtain an intermediate product 3; then carbonate and 0.01-0.5 mol of a basic catalyst (for example, at least one of potassium carbonate, sodium methoxide, sodium bicarbonate, etc.) are added to react to obtain an intermediate product 4; in the After adding pure water, carbonate and other solvents to the intermediate product 4, an acid is added to adjust the reaction solution to acidity (pH 6-7) and a hydrolysis reaction is carried out at 5-10°C for 1-4 hours to obtain an intermediate product 5; then 2-5 mol of dichlorothionyl and 5-10 mol of a carbonate solvent (for example, at least one of dimethyl carbonate and diethyl carbonate) are added and reacted at 40-80°C for 12-24 hours under heating conditions to prepare an intermediate product 6; finally, 2-3 mol of an oxidant such as sodium periodate is used to oxidize the intermediate product 6 (the reaction temperature is -10-25°C and the reaction time is 4-8 hours) to obtain the compound shown in structural formula 1.

[0065] Exemplarily, the preparation method of compound 1 is as follows: 1 mol of sorbitol, 10 mol of dimethoxypropane and a catalyst (sodium bicarbonate) are placed in a reaction vessel and reacted at 25°C for 12 hours to obtain an intermediate product 3; then carbonate and 0.1 mol of an alkaline catalyst (potassium carbonate) are added to react to obtain an intermediate product 4; after adding pure water, carbonate and other solvents to the intermediate product 4, an acid is added to adjust the reaction solution to acidity (pH 6-7) and a hydrolysis reaction is carried out at 10°C for 3 hours to obtain an intermediate product 5; then 5 mol of dichlorothionyl and 7 mol of dimethyl carbonate are added and reacted at 60°C for 20 hours under heating conditions to prepare an intermediate product 6; finally, 2.5 mol of sodium periodate is used to oxidize the intermediate product 6 (the reaction temperature is -10°C-25°C, and the reaction time is 4-8 hours) to obtain compound 1 shown in structural formula 1.

[0066] Exemplarily, the preparation method of compound 2 is: 1 mol of mannitol, a catalyst potassium iodide and 10 mol of an organic solvent DMSO are placed in a reaction vessel, and a condensed water reflux device and a mechanical stirring device are set up at the same time. The reaction is carried out under high temperature conditions of 70-90°C, chlorine gas is introduced under stirring, and the reaction is carried out for 1-5 hours. The reaction is terminated in time by TLC spot plate monitoring, and then a certain amount of sodium bicarbonate is added to adjust the pH to neutral, the salt generated by the acid-base neutralization reaction is filtered out, and the remaining solution is concentrated under reduced pressure. The concentrated solid is dissolved in ethyl acetate / ethanol and recrystallized to obtain the intermediate product 1. Then, 1 mol of intermediate 1, 3 mol of dimethoxypropane and catalyst sodium bicarbonate are placed in a reaction vessel and reacted at 10-25°C for 6-12 hours to obtain intermediate 2; 1 mol of intermediate 2, 3 mol of sodium bisulfite and 10 mol of organic solvent DMSO are placed in a reaction vessel, and a condensed water reflux device and a mechanical stirring device are set up at the same time. The reaction is carried out at a high temperature of 70-90°C for 2-6 hours, and then sulfuric acid is added, concentrated at 110 degrees Celsius for 4 hours, washed with a carbonate solvent, and the solution is concentrated to obtain intermediate 3; pure water, carbonate solvents, etc. are added to intermediate 3. After the agent is added, an acid is added to adjust the reaction solution to acidity (pH 6-7), and a hydrolysis reaction is carried out at 5-10°C for 1-4h to obtain an intermediate product 4; then 1 mol of the intermediate product 4, 5 mol of dimethyl carbonate, 2.5 mol of dichlorothionyl, 0.05 mol of the catalyst DMF, etc. are placed in a new reaction container, and an esterification reaction is carried out at a high temperature of 40-80°C to obtain an intermediate product 5, and then 2-3 mol of an oxidant such as sodium periodate is used to oxidize the intermediate product 5 (the reaction temperature is -10°C to 25°C, and the reaction time is 4-8h) to obtain a compound 2 having the structural formula 1.

[0067] Exemplarily, the preparation method of compound 3 is as follows: 1 mol of galactitol, 5 mol of diphenyl carbonate, an alkaline substance catalyst sodium bicarbonate and 5 mol of an organic solvent DMF are placed in a reaction vessel, and a condensed water reflux device and a mechanical stirring device are set up at the same time, and the reaction is carried out at a high temperature of 70-90°C. The reaction is carried out at high temperature for 5-8 hours, and the TLC spot plate is monitored. At this time, the reaction is continued at 30-50°C for 10-16 hours, and then a certain amount of oxalic acid is added to adjust the pH to neutral, the salt generated by the acid-base neutralization reaction is filtered out, and the remaining solution is concentrated under reduced pressure. The concentrated solid is dissolved in ethyl acetate / ethanol and recrystallized to obtain the intermediate product 1. Then, 1 mol of intermediate product 1, 2-10 mol of diethyl carbonate, 2-5 mol of dichlorothionyl, 0.01-0.5 mol of catalyst DME, etc. are placed in a new reaction container, and an esterification reaction occurs at a high temperature of 40-80°C to obtain intermediate product 2. Then, 2-3 mol of an oxidant such as sodium periodate is used to oxidize intermediate product 2 (the reaction temperature is -10°C to 25°C, and the reaction time is 4-8h) to obtain compound 3 having the structural formula 1.

[0068] Exemplarily, the preparation method of compound 4 is as follows: 1 mol of mannitol dichloride, 5 mol of dimethoxypropane and catalyst triethylamine are placed in a reaction vessel and reacted at 25°C for 6 hours to obtain intermediate product 2; 1 mol of intermediate product 2, 4 mol of sodium bisulfite and 10 mol of organic solvent DMSO are placed in a reaction vessel, and a condensed water reflux device and a mechanical stirring device are set up at the same time, and the reaction is carried out at a high temperature of 70-90°C for 2-6 hours, and then sulfuric acid is added, concentrated at 110 degrees Celsius for 4 hours, washed with a carbonate solvent, and the solution is concentrated to obtain intermediate 3; pure After adding water, carbonate and other solvents, acid is added to adjust the reaction solution to acidity (pH 6-7), and hydrolysis reaction is carried out at 5-10°C for 1-4h to obtain intermediate product 4; then 1 mol of intermediate product 4, 5 mol of dimethyl carbonate, 2.5 mol of dichlorothionyl, 0.05 mol of catalyst DMF, etc. are placed in a new reaction container, and esterification reaction is carried out at a high temperature of 40-80°C to obtain intermediate product 5, and then 3 mol of sodium hypochlorite solution is used to oxidize intermediate product 5 (reaction temperature is -10°C to 25°C, reaction time is 4-8h), and compound 4 having the structural formula of formula 1 can be obtained.

[0069] Exemplarily, the preparation method of compound 5 is as follows: 1 mol of galactitol monochloride, 5 mol of dimethoxypropane and a catalyst sodium carbonate are placed in a reaction vessel and reacted at 10°C for 8 hours to obtain an intermediate product 2; 1 mol of the intermediate product 2, 4 mol of sodium bisulfite and 10 mol of an organic solvent DMSO are placed in a reaction vessel, and a condensed water reflux device and a mechanical stirring device are set up at the same time, and the reaction is carried out at a high temperature of 70-90°C for 2-6 hours, and then sulfuric acid is added, concentrated at 110 degrees Celsius for 4 hours, washed with a carbonate solvent, and the solution is concentrated to obtain an intermediate 3; pure water, After adding solvents such as carbonate, an acid is added to adjust the reaction solution to acidity (pH 6-7), and a hydrolysis reaction is carried out at 5-10°C for 1-4h to obtain intermediate product 4; then 1 mol of intermediate product 4, 5 mol of dimethyl carbonate, 2.5 mol of dichlorothionyl, 0.05 mol of catalyst DMF, etc. are placed in a new reaction container, and an esterification reaction is carried out at a high temperature of 40-80°C to obtain intermediate product 5, and then 2-3 mol of an oxidant such as sodium periodate is used to oxidize intermediate product 5 (the reaction temperature is -10°C to 25°C, and the reaction time is 4-8h) to obtain compound 5 having the structural formula 1.

[0070] Exemplarily, the preparation method of compound 6 is: 1 mol of galactitol, 3.3 mol of thionyl chloride and 0.02 mol of catalyst DME are placed in a reaction container, 10 mol of ethyl methyl carbonate is used as a solvent, and an esterification reaction is carried out under reflux ventilation at 40-80°C to obtain an intermediate product 2, and then the intermediate product 2 is oxidized using 2.3 mol of sodium periodate (the reaction temperature is -10°C to 25°C, and the reaction time is 4-8h) to obtain a compound 6 having the structural formula 1.

[0071] As a preferred example, the metal cation includes at least one of a ruthenium cation, a manganese cation, a titanium cation, and a tungsten cation.

[0072] It should be noted that in the embodiments of the present application, when the metal cation in the color inhibitor has multiple valences, it can be one or more of the various valence states of the metal cation. For example, when the metal cation in the color inhibitor is a vanadium ion, the vanadium ion can be any one or more of a +2-valent vanadium ion, a +3-valent vanadium ion, a +4-valent vanadium ion, and a +5-valent vanadium ion.

[0073] In the embodiments of the present application, the compound containing metal cations is not limited, and can be at least one of metal salts, metal complexes, metal complexes, etc., preferably metal salts. Although metal oxides also contain metal cations, their solubility is generally poor, so the color blocking effect is relatively weak.

[0074] In the embodiments of the present application, the color inhibitor acts as a metal cation, so there is no restriction on the anions in the metal salt. However, considering the price and solubility of the metal salt, the anions in the metal salt are preferably fluoride ions, and secondarily at least one of sulfate ions, chloride ions, bromide ions, etc.

[0075] In some embodiments, the mass content of the metal cation in the cyclic sulfate solution is 1-1000ppm. When the color inhibitor content is within the above range, the color stability of the cyclic sulfate solution can be effectively maintained; if the color inhibitor content is too little (for example, less than 1ppm), it is difficult to significantly improve the color problem of the cyclic sulfate solution; if the color inhibitor content is too much (for example, greater than 1000ppm), it may limit the use environment of the cyclic sulfate solution due to its excessive content, and increase the production and preparation cost.

[0076] Exemplarily, the mass content of the metal cation in the cyclic sulfate solution includes but is not limited to 1 ppm, 10 ppm, 30 ppm, 50 ppm, 80 ppm, 100 ppm, 150 ppm, 200 ppm, 250 ppm, 300 ppm, 350 ppm, 400 ppm, 450 ppm, 500 ppm, 550 ppm, 600 ppm, 650 ppm, 700 ppm, 750 ppm, 800 ppm, 850 ppm, 900 ppm, 950 ppm or 1000 ppm, etc.

[0077] As a preferred example, considering the cost, the mass content of the metal cation in the cyclic sulfate solution is greater than 1 ppm and less than 100 ppm, and more preferably 5 ppm.

[0078] As another preferred example, considering the color blocking effect, the mass content of the metal cation in the cyclic sulfate solution is above 100 ppm, more preferably 500 ppm.

[0079] In some embodiments, based on the total mass of the cyclic sulfate ester solution being 100%, the mass content of the compound represented by structural formula I in the cyclic sulfate ester solution is 0.01% to 60%.

[0080] Illustratively, the mass content of the compound represented by the structural formula I in the cyclic sulfate solution includes but is not limited to 0.5%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55% or 60%, etc.

[0081] As a preferred example, based on the total mass of the cyclic sulfate ester solution being 100%, the mass content of the compound represented by the structural formula I in the cyclic sulfate ester solution is 15-45%, more preferably 25-35%.

[0082] In some embodiments, the organic solvent includes, but is not limited to, at least one of ether solvents, nitrile solvents, carbonate solvents, carboxylate solvents, and sulfone solvents.

[0083] In some embodiments, the ether solvent includes at least one of a cyclic ether and a chain ether.

[0084] Exemplarily, the cyclic ether includes but is not limited to at least one of 1,3-dioxolane (DOL), 1,4-dioxolane (DX), crown ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-CH3-THF), 2-trifluoromethyltetrahydrofuran (2-CF3-THF), etc.

[0085] Exemplarily, the chain ether includes but is not limited to at least one of dimethoxymethane (DMM), 1,2-dimethoxyethane (DME), diethylene glycol dimethyl ether (TEGDME), and the like.

[0086] In some embodiments, the nitrile solvent includes but is not limited to at least one of acetonitrile, glutaronitrile, malononitrile, and the like.

[0087] In some embodiments, the carbonate solvent includes at least one of a cyclic carbonate and a linear carbonate.

[0088] Exemplarily, the cyclic carbonate includes, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone (GBL), butylene carbonate (BC), and the like.

[0089] Exemplarily, the chain carbonate includes, but is not limited to, at least one of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), and the like.

[0090] In some embodiments, the carboxylate solvent includes but is not limited to at least one of methyl acetate (MA), ethyl acetate (EA), propyl acetate (EP), butyl acetate, propyl propionate (PP), butyl propionate, and the like.

[0091] In some embodiments, the sulfone solvent includes at least one of sulfolane and dimethyl sulfoxide.

[0092] As an optional example, the cyclic sulfate ester solution consists of the cyclic sulfate ester compound, the color inhibitor and the organic solvent.

[0093] In the embodiments of the present application, the organic solvent serves to dissolve the cyclic sulfate compound and the color inhibitor.

[0094] The cyclic sulfate solution of the embodiment of the present application, due to the addition of a color inhibitor, can greatly improve the discoloration problem of the sulfate solution during storage at a relatively low cost. This may be attributed to the fact that the color inhibitor can prevent the transfer, transition and conjugation of the cyclic sulfate electrons in the solution, inhibit the formation of auxochromes with a dark effect, and prevent the color from further deepening. Therefore, the cyclic sulfate solution to which the color inhibitor is added has better chromaticity stability during storage, and improves the environmental adaptability of the cyclic sulfate solution.

[0095] <Method for preparing cyclic sulfate solution>

[0096] The method for preparing the cyclic sulfate solution of the embodiment of the present application comprises the following steps:

[0097] S101, adding the color inhibitor to part of the organic solvent to obtain a first mixed solution.

[0098] S102, using another portion of the organic solvent to grade-dilute the first mixed solution to obtain a second mixed solution.

[0099] In some embodiments, the mass content of the metal cations in the second mixed solution is the same as the mass content of the metal cations in the final solution.

[0100] S103, adding the cyclic sulfate ester compound into the second mixed solution and mixing well to obtain the cyclic sulfate ester solution of the application example.

[0101] In the embodiments of the present application, a color inhibitor is added to an organic solvent and then a cyclic sulfate compound is dissolved to prepare a cyclic sulfate solution, which can improve the discoloration problem, realize product solubilization, and avoid quality risks.

[0102] <Electrolyte>

[0103] The electrolyte of the embodiment of the present application includes the cyclic sulfate ester solution of the embodiment of the present application, or includes the cyclic sulfate ester solution prepared by the preparation method of the embodiment of the present application.

[0104] In some embodiments, the mass content of the cyclic sulfate ester solution in the electrolyte is 5%-60%, including but not limited to 5%, 15%, 25%, 35% or 45%, etc.

[0105] <Secondary Battery>

[0106] The secondary battery of the embodiment of the present application includes a positive electrode, a negative electrode, a separator and an electrolyte, and the electrolyte is the electrolyte of the embodiment of the present application.

[0107] In some embodiments, the secondary battery includes but is not limited to a lithium ion battery, a sodium ion battery, and the like.

[0108] In the embodiments of the present application, there is no limitation on the positive electrode, the negative electrode and the separator, and they may be any positive electrode, negative electrode and separator used for secondary batteries in the art.

[0109] The electrolyte and the secondary battery of the embodiment of the present application both have at least the beneficial effects of the cyclic sulfate solution of the embodiment of the present application.

[0110] Certain features of the present technology are further illustrated in the following non-limiting examples.

[0111] 1. Examples and Comparative Examples

[0112] The cyclic sulfate compounds involved in the following examples and comparative examples are all selected from Table 1.

[0113] Table 1 Cyclic sulfate compounds involved in the examples and comparative examples

[0114]

[0115]

[0116]

[0117]

[0118] Example 1

[0119] The cyclic sulfate solution of this embodiment is prepared by adding a color inhibitor solid tungsten hexachloride to ethylene carbonate (EC) in a glove box (water content <10ppm, oxygen content <1ppm) to prepare a tungsten hexachloride solution, and diluting it with a solvent EC graded according to the analysis operation to form an EC solution mixed solution containing 5ppm tungsten as shown in Table 2, and then adding compound 1 to the mixed solution, stirring evenly to obtain the cyclic sulfate solution of this embodiment. As shown in Table 2, the mass proportion of compound 1 is 35%, the mass proportion of solvent EC is 65%, and the mass proportion of the color inhibitor is 5ppm.

[0120] Examples 2-47 and Comparative Examples 1-27 are substantially the same as Example 1, except that some material selections and parameter selections are different, as shown in Table 2.

[0121] Table 2 Composition of the prepared cyclic sulfate solution of Examples 1-47 and Comparative Examples 1-27

[0122]

[0123]

[0124]

[0125] Note: Comparative Examples 1-27 in Table 2 are all cases where different compounds are selected from the cyclic sulfate ester compound in Example 1 without adding a color inhibitor.

[0126] 2. Performance Test

[0127] Chromaticity change of cyclic sulfate solution: The cyclic sulfate solution prepared in each embodiment and comparative example was placed in a sealed aluminum bottle and stored at 35°C. The color change was tested regularly at 0 days (prepared initial solution), 30 days, 60 days and 90 days. The color change was measured using the national standard GB / T3143 1982 liquid chemical color determination method (Hazen unit, platinum-cobalt color number). The test results are shown in Table 3.

[0128] Table 3 Chromaticity changes of cyclic sulfate solutions prepared in various embodiments and comparative examples

[0129]

[0130]

[0131]

[0132] According to Table 3:

[0133] By comparing the test results of Examples 1-6, Examples 26-47 with Comparative Examples 1-27, it can be seen from the chromaticity changes of the cyclic sulfate solutions of the Examples and Comparative Examples in Table 3 that the color inhibitor described in the present application has a significant effect in inhibiting the increase in the chromaticity of the cyclic sulfate solution. The color inhibitor of the present invention has a certain protective effect on a variety of cyclic sulfate compounds, including the compound shown in Structural Formula 1.

[0134] Combined with the test results of Examples 7-9, it can be seen that the color blocking effect is slightly enhanced as the color blocking agent content is increased. Considering the cost, the color blocking agent content is preferably 5ppm. Considering the color blocking effect, the color blocking agent content is preferably 500ppm.

[0135] Combined with the test results of Examples 10-14, it can be seen that the effect of the color inhibitor is greatly affected by the type of metal cation, and is less affected by the concentration of the cyclic sulfate solution and the type of solvent.

[0136] Combining the test results of Examples 15-19 and 24-25, it can be seen that the color blocking effect of the color blocking agent is affected by the valence state of the metal cation, and the same metal with different valence states has different color blocking effects on the cyclic sulfate solution. It is speculated that this may be due to the different electron-withdrawing abilities of metal cations with different valence states in the solution.

[0137] Combined with the test results of Examples 20-23, it can be seen that the color blocking effect is affected by both the concentration of the cyclic sulfate solution and the concentration of the color blocking agent. The lower the sulfate concentration, the slower the color change, and the smaller the color blocking requirement of the color blocking agent.

[0138] In summary, the present application solves the chromaticity problem of the cyclic sulfate ester solution during transportation and storage by adding a color inhibitor into the cyclic sulfate ester solution, thereby ensuring the quality and controlling the preparation cost of the cyclic sulfate ester solution.

[0139] In the present application, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0140] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0141] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A cyclic sulfate solution, characterized in that It includes a cyclic sulfate compound, a color inhibitor and an organic solvent; the color inhibitor includes a compound containing metal cations, and the metal cations include at least one of tungsten cations, molybdenum cations, nickel cations, cobalt cations, vanadium cations, niobium cations, titanium cations, manganese cations, ruthenium cations, platinum cations, and palladium cations.

2. The cyclic sulfate solution according to claim 1, characterized in that The cyclic sulfate ester compounds include compounds having a structure of Formula 1: In Formula 1, R1, R2, and R5 are each independently selected from One of, and at least one of R1, R2, R5 is R3 and R4 are each independently selected from one of H, a halogen atom, a C1-C5 halogenated hydrocarbon group or a C1-C5 hydrocarbon group, m and n are both integers of 0-3, and m and n are not 0 at the same time.

3. The cyclic sulfate solution according to claim 2, characterized in that The m and the n are both 1; and / or, The R3 and R4 are each independently selected from one of H or a halogen atom; and / or, Taking the total mass of the cyclic sulfate solution as 100%, the mass content of the cyclic sulfate compound represented by the structural formula I in the cyclic sulfate solution is 0.01% to 60%, preferably 15-45%, and more preferably 25-35%.

4. The cyclic sulfate solution according to claim 2 or 3, characterized in that The cyclic sulfate ester compound having the structure of Formula 1 includes at least one of compounds 1-6:

5. The cyclic sulfate solution according to claim 1, characterized in that The metal cation includes at least one of a ruthenium cation, a manganese cation, a titanium cation, and a tungsten cation; and / or, The compound containing metal cations includes at least one of metal salts, metal complexes, and metal complexes, and the anions in the metal salts include at least one of fluoride ions, sulfate ions, chloride ions, and bromide ions, preferably fluoride ions; and / or, The mass content of the metal cation in the cyclic sulfate solution is 1-1000 ppm.

6. The cyclic sulfate solution according to claim 1, characterized in that The organic solvent includes at least one of an ether solvent, a nitrile solvent, a carbonate solvent, a carboxylate solvent and a sulfone solvent.

7. The cyclic sulfate solution according to claim 6, characterized in that The ether solvent includes at least one of cyclic ether and chain ether; and / or, the nitrile solvent includes at least one of acetonitrile, glutaronitrile and malononitrile; and / or, The carbonate solvent includes at least one of a cyclic carbonate and a chain carbonate; and / or, The carboxylate solvent includes at least one of methyl acetate, ethyl acetate, propyl acetate, butyl acetate, propyl propionate and butyl propionate; and / or, The sulfone solvent includes at least one of sulfolane and dimethyl sulfoxide.

8. A method for preparing a cyclic sulfate solution according to any one of claims 1 to 7, characterized in that: include: Adding the color inhibitor to part of the organic solvent to obtain a first mixed solution; Using another portion of the organic solvent to grade-dilute the first mixed solution to obtain a second mixed solution; The cyclic sulfate ester compound is added into the second mixed solution and mixed to obtain the cyclic sulfate ester solution.

9. An electrolyte, characterized in that: The invention comprises the cyclic sulfate ester solution as claimed in any one of claims 1 to 7 or the cyclic sulfate ester solution prepared by the preparation method as claimed in claim 8.

10. A secondary battery comprising a positive electrode, a negative electrode, a separator and an electrolyte, characterized in that: The electrolyte is the electrolyte as claimed in claim 9.

Images