Cyclic sulfate solution and application thereof

Abstract

The invention discloses a cyclic sulfate solution and application thereof. The cyclic sulfate solution comprises a cyclic sulfate compound, a protective agent, an organic solvent and water, the cyclic sulfate compound comprises a compound with a structural formula 1, the protective agent comprises a compound with a structural formula 2: # imgabs 0 # imgabs 1 #, R1, R2, R5, R6 and R7 are independently selected from one of # imgabs 2 #, at least one of R1, R2 and R5 is selected from one of # imgabs 3 #, R3, R4, R8 and R9 are independently selected from one of H, halogen atoms, C1-C5 halogenated alkyl or C1-C5 alkyl, and the protective agent comprises a compound with a structural formula 2 as shown in the specification. M and n are integers from 0 to 3, and m and n are not 0 at the same time. The solution provided by the invention contains the protective agent, so that the storage time of the cyclic sulfate solution can be prolonged, and the quality risk is avoided while the product is solubilized.

Description

Technical Field

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

[0002] At present, the application of secondary batteries is developing rapidly in various fields. Electrolyte additives are also being updated. Among them, cyclic sulfate compounds are widely used as additives due to their excellent performance. Cyclic sulfate compounds are unstable to water, produce fuming sulfuric acid, are corrosive, and direct storage and transportation are highly harmful to personnel and equipment. They are usually prepared into solutions for storage and transportation.

[0003] However, after being prepared into a solution, it will react with water in the solution, and the sulfate content will decrease. In order to extend the shelf life of the sulfate solution and ensure the main content of sulfate, distillation or molecular sieve treatment is usually used to pre-treat the water in the solvent. However, this method has the risk of increasing production costs and introducing harmful impurities.

[0004] Therefore, there is an urgent need to develop a cyclic sulfate solution with stable composition and good storage performance. Summary of the invention

[0005] In view of this, an object of the present application is to provide a cyclic sulfate ester solution, which contains a protective agent and can extend the storage time of the cyclic sulfate ester solution. While the product is solubilized, quality risks are avoided.

[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 provides a cyclic sulfate solution, comprising a cyclic sulfate compound, a protective agent, an organic solvent and water;

[0009] The cyclic sulfate ester compound includes a compound having a structural formula of Formula 1, and the protective agent includes a compound having a structural formula of Formula 2;

[0010]

[0011]

[0012] Wherein, R1, R2, R5, R6, and R7 are each independently selected from One of, and at least one of R1, R2, R5 is R3, R4, R8, and R9 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.

[0013] In some embodiments, m and n are both 1.

[0014] In some embodiments, R1, R2, R6, and R7 are each independently selected from One of them.

[0015] In some embodiments, R3, R4, R8, and R9 are each independently selected from a C1-C5 halogenated hydrocarbon group or a C1-C5 hydrocarbon group.

[0016] In some embodiments, the cyclic sulfate ester compound having the structural formula 1 includes at least one of compounds T1-T6:

[0017]

[0018] In some embodiments, the compound having the structure of Formula 2 includes at least one of compounds P1-P6:

[0019]

[0020] In some embodiments, the water content in the cyclic sulfate solution is less than 5000 ppm by mass.

[0021] In some embodiments, based on the total mass of the cyclic sulfate ester solution being 100%, the mass content of the cyclic sulfate ester compound having the structural formula 1 is 0.01-60%.

[0022] In some embodiments, the mass content of the protective agent in the cyclic sulfate ester solution is 100-10000 ppm.

[0023] 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.

[0024] In some embodiments, the ether solvent includes at least one of a cyclic ether and a chain ether.

[0025] In some embodiments, the nitrile solvent includes at least one of acetonitrile, glutaronitrile, and malononitrile.

[0026] In some embodiments, the carbonate solvent includes at least one of a cyclic carbonate and a linear carbonate.

[0027] 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.

[0028] In some embodiments, the sulfone solvent includes at least one of sulfolane and dimethyl sulfoxide.

[0029] In some embodiments, the cyclic sulfate ester solution can be obtained by mixing a cyclic sulfate ester compound, a preservative and an organic solvent. The water contained in the cyclic sulfate ester solution can be water in the organic solvent, or water absorbed from the environment during the mixing process.

[0030] The second aspect of the present application provides an electrolyte comprising the cyclic sulfate solution described in the present application.

[0031] The third 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.

[0032] The cyclic sulfate solution described in the present application can at least bring the following beneficial effects:

[0033] The cyclic sulfate solution, due to containing a protective agent, can play a greater improvement effect on the hydrolysis problem in the storage process of the cyclic sulfate solution at a relatively low cost, which may be attributed to the fact that the slowest step of the ester hydrolysis reaction is the attack of water molecules on the protonated ester molecules. The hydrolysis rate is related to the substituent effect, and the larger the substituent volume, the slower the hydrolysis rate. The protective agent can react with water in the solution to generate a hydrolysis product with a large substituent, and does not react or reacts very slowly with the cyclic sulfate compound (compound with formula 1 structure), slowing down the hydrolysis of the cyclic sulfate compound and extending the storage time of the cyclic sulfate compound. Therefore, the cyclic sulfate solution to which the protective agent is added has better content stability during storage, improves the environmental adaptability of the solution, and extends the storage time of the cyclic sulfate solution.

[0034] 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

[0035] The embodiments of the present application are described in detail below. The embodiments described below are exemplary and intended to be used to explain the present application, but should not be construed as limiting the present application.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] The inventors found that cyclic sulfate solutions are generally acidic, and cyclic sulfate compounds are hydrolyzed by free acid catalysis, and the acid-catalyzed reaction is reversible. The slowest step of the reaction is the attack of water molecules on protonated ester molecules. The hydrolysis rate is related to the substituent effect. The larger the substituent volume, the slower the hydrolysis rate. Therefore, it is necessary to find a protective agent that meets the following conditions: the product substituent after the protective agent is hydrolyzed is large, and it does not react or reacts very slowly with the cyclic sulfate compounds; other impurity ions are not introduced to affect the use of the cyclic sulfate solution. The inventors further found that the compound with the structure of formula 2 meets the above conditions, and adding it as a protective agent to the cyclic sulfate solution can extend the storage time of the cyclic sulfate solution at a smaller addition amount.

[0042] The cyclic sulfate solution and the like of the embodiments of the present application are described in detail below.

[0043] <Cyclic Sulfate Ester Solution>

[0044] The cyclic sulfate solution of the embodiment of the present application comprises a cyclic sulfate compound, a protective agent, an organic solvent and water. Among them:

[0045] The cyclic sulfate ester compound includes a compound having a structural formula of Formula 1, and the protective agent includes a compound having a structural formula of Formula 2;

[0046]

[0047] Wherein, R1, R2, R5, R6, and R7 are each independently selected from One of, and at least one of R1, R2, R5 is R3, R4, R8, and R9 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.

[0048] In some embodiments, the halogen atom includes a fluorine atom (F), a chlorine atom (Cl), a bromine atom (Br), or an iodine atom (I).

[0049] 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).

[0050] 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.

[0051] 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.

[0052] Exemplarily, the values ​​of m and n are both 0, 1, 2 or 3, and m and n are not 0 at the same time.

[0053] It should be noted that, in the embodiments of the present application, when m>1 and n>1, R1, R2, R3, and R4 may be the same or different.

[0054] As an optional example, m and n are both 1.

[0055] As an optional example, R1, R2, R6, and R7 are each independently selected from One of them.

[0056] As an optional example, R3, R4, R8, and R9 are each independently selected from a C1-C5 halogenated hydrocarbon group or a C1-C5 hydrocarbon group.

[0057] As a preferred example, the cyclic sulfate ester compound having the structural formula 1 includes but is not limited to at least one of compounds T1-T6, etc.:

[0058]

[0059] It should be noted that the above compounds T1-T6 are only preferred compounds among the cyclic sulfate compounds having the structural formula 1, and are not intended to limit the present application.

[0060] In some embodiments, the cyclic sulfate ester compound having the structural formula 1 can be prepared by the following preparation method:

[0061] A polyol, a carbonate, an alkaline catalyst (e.g., at least one of potassium carbonate, sodium methoxide, sodium bicarbonate, etc.) and an organic solvent (e.g., at least one of ethyl methyl carbonate (EMC), dimethyl sulfoxide (DMSO), etc.) are placed in a reaction vessel, and a condensed water reflux device and a mechanical stirring device are set up, 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, the intermediate product 1, carbonate, dichlorothionyl, etc. are placed in a new reaction container, and an esterification reaction occurs under high temperature conditions of 40-80°C to obtain the intermediate product 2. Then, the intermediate product 2 is oxidized using an oxidant such as sodium periodate (the reaction temperature is -10°C to 25°C, and the reaction time is 4-8h) to obtain a cyclic sulfate compound having the structural formula 1.

[0062] In other embodiments, the cyclic sulfate compound having the structural formula 1 can be prepared by the following preparation method:

[0063] A polyol, 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 an alkaline catalyst (for example, at least one of potassium carbonate, sodium methoxide, sodium bicarbonate, etc.) 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 is 6-7) and a hydrolysis reaction is carried out at 5-10°C for 1-4 hours to obtain an intermediate product 5; then dichlorothionyl and carbonate solvents are added and reacted at 40-80°C for 12-24 hours under heating conditions to prepare an intermediate product 6; finally, 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 a cyclic sulfate compound shown in structural formula 1.

[0064] As a preferred example, the compound having the structure of Formula 2 includes but is not limited to at least one of compounds P1-P6, etc.:

[0065]

[0066] It should be noted that the above compounds P1-P6 are merely preferred compounds among the compounds having the structural formula 2 and are not intended to limit the present application.

[0067] In some embodiments, the preparation method of the compound having the structural formula 2 is as follows: different reaction monomers are obtained by using different reaction conditions for polyols, which are reacted with thionyl diimidazole / dichlorothionyl in sequence to obtain a crude product having the structural formula 2, which is further purified by HPLC preparation and separation.

[0068] Exemplary: 1 mol of glycerol is reacted with 5 mol of dimethyl carbonate under reflux, reacted at 80 degrees Celsius for 4 hours, and the solution is concentrated under reduced pressure to obtain a crude intermediate 1, which is then passed through a molecular distillation apparatus to obtain intermediate 1; 1 mol of intermediate 1 is reacted with 1 mol of thionyl chloride at 80 degrees Celsius for 4 hours, and the reaction is ventilated until no gas is produced to terminate the reaction, and the crude product is purified by column chromatography to obtain compound P1.

[0069] In some embodiments, based on the total mass of the cyclic sulfate ester solution being 100%, the mass content of the cyclic sulfate ester compound having the structural formula 1 is 0.01-60%.

[0070] Illustratively, the mass content of the cyclic sulfate 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.

[0071] In some embodiments, the mass content of the protective agent in the cyclic sulfate solution is 100-10000 ppm. When the protective agent content is within the above range, the content of the additive can be effectively maintained. If the protective agent content is too little, it is difficult to significantly improve the content of the additive; if the content is too much, the use environment of the solution may be limited due to the excessive amount, and the production and preparation cost may be increased.

[0072] Exemplarily, the mass content of the protective agent in the cyclic sulfate solution includes but is not limited to 100ppm, 500ppm, 1000ppm, 1500ppm, 2000ppm, 2500ppm, 3000ppm, 3500ppm, 4000ppm, 4500ppm, 5000ppm, 5500ppm, 6000ppm, 6500ppm, 7000ppm, 7500ppm, 8000ppm, 8500ppm, 9500ppm or 10000ppm, etc.

[0073] It should be noted that, considering the content of the protective additive, it is preferably above 5000 ppm, more preferably 5000 ppm. The protective effect is more obvious when the amount of the protective agent added accounts for at least 100 ppm of the mass of the cyclic sulfate solution.

[0074] In some embodiments, the mass content of water in the cyclic sulfate solution is less than 5000 ppm. In the examples of the present application, the mass content of water in the cyclic sulfate solution is within the above range, and the protective agent has a significant effect of inhibiting hydrolysis; if it exceeds 5000 ppm, there is still a risk of causing hydrolysis of cyclic sulfate compounds.

[0075] Exemplarily, the mass content of the water in the cyclic sulfate solution includes but is not limited to 1 ppm, 25 ppm, 50 ppm, 75 ppm, 100 ppm, 500 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, 3500 ppm, 4000 ppm, 4500 ppm or 5000 ppm.

[0076] In the embodiments of the present application, the organic solvent serves to dissolve the cyclic sulfate compound and the protective agent.

[0077] 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.

[0078] In some embodiments, the ether solvent includes at least one of a cyclic ether and a chain ether.

[0079] 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.

[0080] 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.

[0081] In some embodiments, the nitrile solvent includes but is not limited to at least one of acetonitrile, glutaronitrile, malononitrile, and the like.

[0082] In some embodiments, the carbonate solvent includes at least one of a cyclic carbonate and a linear carbonate.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] In some embodiments, the sulfone solvent includes at least one of sulfolane and dimethyl sulfoxide.

[0087] In some embodiments, the cyclic sulfate ester solution can be obtained by mixing a cyclic sulfate ester compound, a preservative and an organic solvent, wherein the water contained therein can be the water in the organic solvent, or the water absorbed from the environment during the mixing process.

[0088] The solution of the embodiment of the present application, the solution is a cyclic sulfate solution, due to the presence of a protective agent, can be used at a relatively low cost to improve the hydrolysis problem in the storage process of the cyclic sulfate solution, which may be attributed to the slowest step of the ester hydrolysis reaction is the attack of water molecules on protonated ester molecules. The hydrolysis rate is related to the substituent effect, and the larger the substituent volume, the slower the hydrolysis rate. The protective agent can react with water in the solution to generate a hydrolyzate with a large substituent, and does not react or reacts very slowly with the cyclic sulfate compound (compound with formula 1 structure), inhibiting its hydrolysis, and extending the storage time of the cyclic sulfate compound. Therefore, the cyclic sulfate solution to which the protective agent is added has better content stability during storage, improves the environmental adaptability of the solution, and extends the storage time.

[0089] <Electrolyte>

[0090] The electrolyte of the embodiments of the present application includes the solution of the embodiments of the present application, or includes a solution prepared by the method for preparing the solution of the embodiments of the present application.

[0091] 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.

[0092] <Secondary Battery>

[0093] 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.

[0094] In some embodiments, the secondary battery includes but is not limited to a lithium ion battery, a sodium ion battery, and the like.

[0095] 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.

[0096] The electrolyte solution and the secondary battery of the embodiments of the present application both have at least the beneficial effects of the solution of the embodiments of the present application.

[0097] Certain features of the present technology are further illustrated in the following non-limiting examples.

[0098] 1. Examples and Comparative Examples

[0099] The compounds with the structure of Formula 1 corresponding to the additives involved in the following examples and comparative examples are all selected from Table 1, and the compounds with the structure of Formula 2 corresponding to the protective agents are all selected from Table 2.

[0100] Table 1 Compounds with the structure of Formula 1 corresponding to the cyclic sulfate compounds involved in the examples and comparative examples

[0101]

[0102]

[0103]

[0104] Table 2 Compounds with the structure of Formula 2 corresponding to the protective agents of the examples and comparative examples

[0105]

[0106] Example 1

[0107] The content of each component of the cyclic sulfate solution of this embodiment is shown in Table 3. In the solution of this embodiment, the mass proportion of the cyclic sulfate compound T1 is 35%, the mass proportion of the organic solvent PC is 65%, the mass proportion of the protective agent compound P1 is 5000ppm, and the mass proportion of water is 500ppm.

[0108] Examples 2-38 are basically the same as Example 1, except that some material selections and parameter values ​​are different, as shown in Table 3.

[0109] Comparative Examples 1-6 are substantially the same as Example 1, except that no protective agent is added.

[0110] Table 3 Cyclic sulfate solutions of various embodiments and comparative examples

[0111]

[0112]

[0113] 2. Performance Test

[0114] Changes in solution content: The solutions prepared in Examples 1-38 and Comparative Examples 1-6 were placed in sealed aluminum bottles and stored at 35°C. Changes in their content were tested regularly at 0 days (prepared fresh solutions), 30 days, 60 days, and 90 days. The changes in content were tested using high performance liquid chromatography (HPLC). The test method is as follows:

[0115] 2.1 Test Principle

[0116] The different retention times of substances on the chromatographic column are used to separate the samples and conduct qualitative and quantitative tests.

[0117] 2.2 Instruments and reagents

[0118] Reagents: chromatographic grade acetonitrile, ultrapure water.

[0119] The test conditions are shown in Table 4.

[0120] Table 4 HPLC test conditions

[0121] Serial number Test conditions Serial number Test conditions 1 Instrument model: UV detector 5 Mobile phase: 60% acetonitrile 2 Chromatographic column model: C18 column 6 Injection volume: 50 μL 3 Column temperature: room temperature (25°C) 7 Flow rate: 1mL / min 4 Injection method: manual injection 8 Running time: 60 minutes

[0122] 2.3 Mobile phase preparation

[0123] First, prepare ultrapure water, filter it with a water membrane, and wash the measuring cylinder, mobile phase storage bottle, etc. Chromatographic grade acetonitrile is ready for use. Finally, use a measuring cylinder to take acetonitrile and ultrapure water to prepare a 60% acetonitrile mobile phase.

[0124] 2.4 Sample solution preparation

[0125] Accurately weigh 5 g of the solution sample of each embodiment or comparative example, dilute it to 20 g with 60% acetonitrile, dissolve it, shake it well, and inject it for testing.

[0126] 2.5 Sample testing

[0127] Turn on the instrument according to the liquid phase operation procedure, then start the operating software and select the instrument test method (1mL / min, mobile phase: 60% acetonitrile, C18 column) and wait for the detector baseline to stabilize. After the baseline is stable, inject a blank sample with the mobile phase (acquisition time is greater than 15min), which is used as a comparison background spectrum after acquisition, and then test the sample (acquisition time 60min).

[0128] 2.6 Sample and data processing

[0129] From the HPLC spectrum, the main peak areas of the protective agent and the cyclic sulfate can be known. The solvent peak area and the protective agent peak area are excluded, and the main peak area is recorded. The main peak area of ​​0 / 30 / 60 / 90 days is tested respectively, and the content of the cyclic sulfate (that is, the compound of structural formula 1 in the present application) = test peak area / 0 day main peak area.

[0130] The test results are shown in Table 5.

[0131] Table 5 Changes in the content of cyclic sulfate in the solutions prepared in Examples 1-38 and Comparative Examples 1-6

[0132]

[0133]

[0134]

[0135] According to Table 5:

[0136] By comparing the test results of Examples 1-38 with Comparative Examples 1-6, it can be seen from the changes in the contents of the Examples and Comparative Examples in Table 5 that the solution containing the protective agent described in the present application has a significant effect in maintaining the content of cyclic sulfate esters, and the protective agent of the present application has a certain protective effect on various compounds having the structure shown in Formula 1.

[0137] Combined with the test results of Examples 7-10 / 17-18, it can be seen that the effect of maintaining the content of cyclic sulfate is slightly enhanced as the content of protective agent increases. Taking all factors into consideration, the content of protective agent is preferably 5000ppm.

[0138] Combined with the test results of 11-13, it can be seen that the content of cyclic sulfate in the solution increased, and the protective effect of 5000ppm protective agent was slightly reduced, but compared with the comparative example, the protective effect was still significant, and the hydrolysis of cyclic sulfate was reduced.

[0139] Combined with the test results of 14-15, it can be seen that under the condition of other constant conditions, as the water content in the solution increases, the protective agent effect weakens. However, compared with the comparative example, the protective effect is still significant, and the hydrolysis of cyclic sulfate is reduced.

[0140] In summary, the present application solves the problem of reduced content of cyclic sulfate during transportation and storage due to the influence of moisture in the solution by adding a protective agent to the cyclic sulfate solution, thereby extending the storage time of the solution and controlling the preparation cost of the solution.

[0141] In the present application, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" and the like 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 specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. 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, unless they are mutually contradictory. Although the embodiments of the present application have been shown and described above, it is to be understood that the above embodiments are exemplary and cannot be construed as limitations on the present application, and those of ordinary skill in the art may change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A cyclic sulfate solution, characterized in that Including cyclic sulfate compounds, protective agents, organic solvents and water; The cyclic sulfate ester compound includes a compound having a structural formula of Formula 1, and the protective agent includes a compound having a structural formula of Formula 2; Wherein, R1, R2, R5, R6, and R7 are each independently selected from One of, and at least one of R1, R2, R5 is R3, R4, R8, and R9 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.

2. The cyclic sulfate solution according to claim 1, characterized in that The mass percentage of water in the cyclic sulfate solution is less than 5000 ppm.

3. The cyclic sulfate solution according to claim 1, characterized in that The m and n are both 1; and / or, The R1, R2, R6, and R7 are each independently selected from one of; and / or, The R3, R4, R8 and R9 are each independently selected from a C1-C5 halogenated hydrocarbon group or a C1-C5 hydrocarbon group.

4. The cyclic sulfate solution according to claim 1, characterized in that The cyclic sulfate ester compound having the structural formula 1 includes at least one of compounds T1-T6: and / or, The compound having the structure of Formula 2 includes at least one of compounds P1-P6:

5. The cyclic sulfate solution according to claim 1, characterized in that Based on the total mass of the cyclic sulfate solution being 100%, the mass content of the cyclic sulfate compound having the structural formula 1 is 0.01-60%.

6. The cyclic sulfate solution according to claim 1, characterized in that The mass content of the protective agent in the cyclic sulfate solution is 100-10000 ppm.

7. 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.

8. The cyclic sulfate solution according to claim 7, characterized in that The ether solvent includes at least one of a cyclic ether and a 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 (MA), ethyl acetate (EA), propyl acetate (EP), butyl acetate, propyl propionate (PP), and butyl propionate; and / or, The sulfone solvent includes at least one of sulfolane and dimethyl sulfoxide.

9. An electrolyte, characterized in that: Comprising the cyclic sulfate solution as described in any one of claims 1 to 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.

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