Trialkyl silicon-based phosphonate sulfate, preparation process and secondary battery electrolyte taking sulfate as additive

Abstract

The invention relates to trialkyl silicon-based phosphonate sulfate, a preparation process thereof and a secondary battery electrolyte using the trialkyl silicon-based phosphonate sulfate as an additive. The electrolyte comprises trialkyl silicon-based phosphonate sulfate, electrolyte salt, a non-aqueous organic solvent and other additives. The structural general formula of the sulfate is # imgabs0 #, wherein n is greater than or equal to 1; r1, R2 and R3 are selected from C1-C6 alkyl groups; the preparation method comprises the following steps: S1, a compound II reacts with a compound III, when X is selected from Br or Cl, a compound IV is obtained, and then the compound IV is hydrolyzed to obtain a compound V; y is selected from C1-C4 alkyl, so as to obtain a compound V; s2, oxidizing the compound V to obtain a compound VI; s3, reacting the compound VI with a trialkyl silicon-based compound to obtain a final product compound I; the reaction formula is as shown in figures. The trialkyl silicon-based phosphonate sulfate is used as a secondary battery electrolyte additive, so that the direct-current internal resistance of the battery can be reduced, the high-temperature cycle and high-temperature storage performance can be improved, and the gas expansion of the battery after high-temperature storage can be inhibited.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical preparation, and in particular relates to a trialkylsilylphosphonate sulfate and a preparation process, as well as a secondary battery electrolyte using the sulfate as an additive. Background Art

[0002] Secondary battery electrolyte additives, as one of the economical and efficient means to improve battery performance, have become the core element of the diversification of electrolyte functions. Usually, only a small amount of additives is needed to significantly improve the key performance indicators of the battery, including rate performance, cycle performance, high and low temperature performance and safety. Additives are the most economical and efficient way to improve battery performance. By screening and matching a small amount of additives, the performance of the electrolyte can be greatly improved. It has been the core research direction in the field of lithium-ion battery electrolytes in recent years.

[0003] The positive electrode film-forming additives in the electrolyte can form a protective film or complex layer on the positive electrode surface, inhibiting the interfacial side reactions between the electrolyte and the positive electrode and the dissolution of transition metal ions, thereby improving the storage and cycle stability under high temperature and high voltage. However, most positive electrode film-forming additives will degrade some electrochemical properties while improving storage and cycle stability. For example, sulfate compounds, especially monocyclic sulfate compounds, have a relatively slightly lower film-forming impedance, but their positive electrode film-forming effect is relatively weak, and the effect of inhibiting storage gas production and positive electrode electrolyte interface side reactions under high voltage is limited. Therefore, their high-temperature storage performance and high-temperature cycle performance need to be improved.

[0004] Therefore, additives are often not used alone in the formulation of electrolytes. In fact, in order to meet functional requirements, the electrolyte usually contains two or more types of additives. Although this approach improves the functionality of the electrolyte, it also increases costs and makes the chemical reaction process inside the battery more complex and changeable.

[0005] Dongguan Shanshan Battery Materials Co., Ltd.'s Chinese patent CN109888386A discloses a chain-like sulfuric acid ester compound M and cyclic sulfonate compounds N The combined additive composition, the compound M can participate in the formation of a passivation film at the interface of the positive and negative electrodes, improve high temperature performance and inhibit battery gas production, but the impedance of the compound M is relatively high, resulting in poor cycle performance of the electrolyte and battery configured therewith.

[0006] The Chinese patent CN118431564A of Zhejiang Blue Sky Environmental Protection High-Tech Co., Ltd. discloses that the first additive is monofluorophosphate fluoroboric acid and the second additive is a bicyclic sulfate compound. The patent also discloses that the additives also include a third additive, and the third additive is selected from at least one of vinylene carbonate, fluoroethylene carbonate, lithium difluorophosphate, bisfluorosulfonyl imide, lithium bisoxalate difluorophosphate, lithium difluorooxalate borate, lithium tetrafluoroborate, tris(trimethylsilyl) borate, and tris(trimethylsilyl) phosphate, and the three additives are used in combination. The electrolyte can effectively reduce the battery impedance, improve the storage and cycle performance of the battery at high temperature and high voltage, and ensure that the battery has good low temperature and rate performance. However, it has no improvement effect on the suppression of gas production, low temperature performance, and capacity retention rate of the battery during high temperature storage.

[0007] Shenzhen Yanyi New Materials Co., Ltd.'s Chinese patent CN114597492A, the additives include aryl sulfate, silicon-containing compounds, fluoroethylene carbonate, and other additives, among which other additives include one or more of triallyl phosphate and tris(trimethylsilyl)phosphate, the non-aqueous electrolyte can improve the high-temperature storage performance of lithium-ion batteries, and significantly improve the low-temperature cycle performance, discharge performance and safety performance of lithium-ion batteries. However, the additives required to achieve the above functions are numerous, the components are complex and the cost is high, but the DC internal resistance is not fundamentally reduced, and there are still defects.

[0008] Therefore, in view of the above shortcomings, it is urgent to develop new additives that can overcome the above defects and inhibit impedance growth in high voltage and high temperature environments, thereby improving battery storage performance and cycle performance and other indicators. Summary of the invention

[0009] The problem to be solved by the present invention is to provide a trialkylsilylphosphonate sulfate and a preparation process, as well as a secondary battery electrolyte using the sulfate as an additive. The trialkylsilylphosphonate sulfate can be used as a secondary lithium battery electrolyte additive to reduce the DC internal resistance of the battery, improve high-temperature cycle and high-temperature storage performance, and inhibit flatulence of the battery after high-temperature storage.

[0010] In order to achieve the above technical effects, the technical solution of the present invention is:

[0011] A secondary battery electrolyte containing trihydrocarbylsilylphosphonate sulfate, the electrolyte comprising trihydrocarbylsilylphosphonate sulfate, electrolyte salt, non-aqueous organic solvent and other additives.

[0012] As a further technical solution, the general structural formula of the trialkylsilylphosphonate sulfate compound I is as follows:

[0013]

[0014]

[0015] Wherein, n≥1, n is preferably 1, 2, or 3; R 1 , R 2 , R 3 The hydrocarbon group selected from C1 to C6 is preferably a cyano hydrocarbon group or a fluorine-containing hydrocarbon group.

[0016] As a further technical solution, the preparation of compound I is divided into three steps:

[0017] S1: Compound II reacts with compound III, and when X in compound III-a is selected from Br or Cl, compound IV is obtained; compound IV is hydrolyzed to obtain compound V; the reaction formula is as follows:

[0018]

[0019] Wherein, R is selected from a hydrogen atom or a C1-C4 alkyl group; n≥1, and n is preferably 1, 2, or 3; and m is 0 or 1;

[0020] Compound II reacts with compound III, and Y in compound III-b is selected from a C1-C4 alkyl group, and no hydrolysis step is required to directly obtain compound V. The reaction formula is as follows:

[0021]

[0022] S2: Compound V is oxidized to obtain compound VI, and reaction formula II is as follows:

[0023]

[0024] S3: Compound VI reacts with a trialkylsilyl compound to obtain a final product, Compound I, and reaction formula III is as follows:

[0025]

[0026] As a further technical solution, in the step S1, the compound III-a is preferably thionyl chloride, and the compound III-b is preferably one of dimethyl sulfite and diethyl sulfite; the molar ratio of compound III to compound II is 2.0 to 5.0:1, and the preferred molar ratio is 2.5 to 4.0:1; the reaction temperature is -20 to 40°C, and the preferred reaction temperature is -10 to 20°C.

[0027] As a further technical solution, in the step S1, the solvent for the reaction of compound II with compound III is at least one of alkanes, halogenated hydrocarbons, esters, and sulfones, specifically, at least one selected from benzene, toluene, xylene, cyclohexane, cyclopentane, dichloromethane, chloroform, ethyl acetate, butyl acetate, dimethyl carbonate, diethyl carbonate, dimethyl sulfoxide, and sulfolane.

[0028] As a further technical solution, in the step S2, compound V is oxidized to obtain compound VI, and the oxidant used is selected from one of hydrogen peroxide, ozone, hypochlorous acid, oxygen, air, sodium hypochlorite, ammonium persulfate, potassium persulfate, potassium hydrogen persulfate, peroxysulfuric acid, sodium percarbonate, sodium perchlorate, sodium periodate, manganese oxide, and potassium permanganate. The preferred oxidants are hydrogen peroxide, sodium hypochlorite, and potassium hydrogen persulfate.

[0029] As a further technical solution, in the step S2, the reaction solvent is selected from an organic solvent or water, preferably an organic solvent; the molar ratio of the active oxygen provided by the oxidant to the compound V is 3.0 to 6.0:1, preferably 3.6 to 4.0:1; and the reaction temperature is -20 to 60°C.

[0030] As a further technical solution, in the step S3, compound VI reacts with a trialkylsilyl compound to obtain a final product compound I, wherein the trialkylsilyl compound is selected from one of trialkylsilazane, trialkylsiloxane or trialkylhalosilane; preferably, the trialkylsilyl compound is selected from hexaalkyldisilazane, hexaalkyldisiloxane, heptaalkyldisilazane, trialkylchlorosilane, trialkylalkoxysilane, trialkylacyloxysilane, trialkylsilylamine, trialkylsilylimidazole, trialkylaminooxysilane, trialkylsilylsilane, trialkylsilylamine, trialkylsilylimidazole, trialkylaminooxysilane, trialkylsilylsilane, trialkylsilylamine, trialkylsilylimidazole, trialkylaminooxysilane, trialkylsilylamine ... At least one of alkenyloxysilane, trialkyloxime silane or N, O-bistrialkylsilyl acetamide; more typically selected from at least one of trimethylchlorosilane, hexamethyldisilazane, heptamethyldisilazane, tetramethyldivinyldisilazane, trimethylmethoxysilane, trimethylethoxysilane, trimethylsilylimidazole, hexamethyldisilurea or N, O-bistrimethylsilyl acetamide, tetramethylbis(trifluoromethyl)disiloxane, tetraisopropyldicyanodisiloxane and tetramethyl-bis(3-cyanopropyl)disilazane.

[0031] As a further technical solution, in the step S3, the molar ratio of the trialkylsilyl compound to compound VI is 2 to 20:1, preferably 4.5 to 12:1; the reaction temperature is -10 to 160°C, and the reaction time is 1 to 40 hours.

[0032] As a further technical solution, other additives are selected from at least one of vinylene carbonate (VC), vinyl carbonate (VEC), fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), vinyl sulfite (ES), methylene methanedisulfonate (MMDS), 1,3-propane sultone (PS), 1,3-propylene sultone (PST), tris(trimethylsilyl) phosphite (TMSPi), tris(trimethylsilyl) borate (TMSB), succinic anhydride (SA), succinonitrile (SN), adiponitrile (ADN), and ethoxypentafluorocyclotriphosphazene (PFPN).

[0033] As a further technical solution, based on 100% of the total mass of the electrolyte, the amount of the trialkylsilylphosphonate sulfate compound additive added is 0.1% to 5%, and the amount of other additives added is 0.1% to 5%.

[0034] As a further technical solution, when the secondary battery is a lithium ion battery, the electrolyte in the electrolyte is one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium difluorophosphate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(oxalatoborate), lithium difluorooxalatoborate, lithium tetrafluorooxalatophosphate, lithium difluorobis(oxalatophosphate), and lithium fluorosulfonyl(trifluoromethylsulfonyl)imide, and the molar concentration of the electrolyte in the electrolyte is 0.5 to 2 mol / L;

[0035] As a further technical solution, when the secondary battery is a sodium ion battery, the electrolyte in the electrolyte is at least one of sodium hexafluorophosphate, sodium difluorophosphate, sodium bisoxalatoborate, sodium difluorooxalatoborate, sodium bis(fluorosulfonyl imide), sodium bis(trifluoromethylsulfonyl imide), sodium trifluoromethylsulfonate, sodium perchlorate, and sodium tetrafluoroborate.

[0036] As a further technical solution, the non-aqueous organic solvent is composed of one or more of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethylene carbonate, ethyl methyl carbonate, methyl propyl carbonate, methyl butyl carbonate, propylene carbonate, γ-butyrolactone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, difluoroethyl acetate, trifluoroethyl acetate, trifluoroethyl methyl carbonate, and bistrifluoroethyl carbonate.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The present invention provides a trialkylsilylphosphonate sulfate and a preparation process, as well as a secondary battery electrolyte using the sulfate as an additive. The trialkylsilylphosphonate sulfate can be used as an additive for secondary lithium battery electrolytes. The additive containing elements such as phosphorus, sulfur, and silicon can reduce the DC internal resistance of the battery, improve high-temperature cycle and high-temperature storage performance, and inhibit flatulence of the battery after high-temperature storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 These are the steps for preparing compound I. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] A secondary battery electrolyte containing trihydrocarbylsilylphosphonate sulfate, the electrolyte comprising trihydrocarbylsilylphosphonate sulfate, electrolyte salt, non-aqueous organic solvent and other additives.

[0042] The general structural formula of the trihydrocarbylsilylphosphonate sulfate compound I is as follows:

[0043]

[0044] Wherein, n≥1, n is preferably 1, 2, or 3; R 1 , R 2 , R 3 The hydrocarbon group selected from C1 to C6 is preferably a cyano hydrocarbon group or a fluorine-containing hydrocarbon group.

[0045] The preparation of compound I is divided into three steps:

[0046] S1: Compound II reacts with compound III, and when X in compound III-a is selected from Br or Cl, compound IV is obtained; compound IV is hydrolyzed to obtain compound V; the reaction formula is as follows:

[0047]

[0048] Wherein, R is selected from a hydrogen atom or a C1-C4 alkyl group; n≥1, and n is preferably 1, 2, or 3; and m is 0 or 1;

[0049] Compound II reacts with compound III, and Y in compound III-b is selected from a C1-C4 alkyl group, and no hydrolysis step is required to directly obtain compound V. The reaction formula is as follows:

[0050]

[0051] S2: Compound V is oxidized to obtain compound VI, and reaction formula II is as follows:

[0052]

[0053] S3: Compound VI reacts with a trialkylsilyl compound to obtain a final product, Compound I, and reaction formula III is as follows:

[0054]

[0055] When R 1 , R 2 , R 3 When it is a group in Table 1, the structure of the trihydrocarbylsilylphosphonate sulfate compound I can be determined.

[0056] Table 1R 1 , R 2 , R 3 Group combination

[0057] Compound n R1 R2 R3 I-1 1 <![CDATA[-CH 3 ]]> <![CDATA[-CH 3 ]]> <![CDATA[-CH 3 ]]> I-2 2 <![CDATA[-CH 3 ]]> <![CDATA[-CH 3 ]]> <![CDATA[-CH 3 ]]> I-3 1 <![CDATA[-CH 2 CH 3 ]]> <![CDATA[-CH 2 CH 3 ]]> <![CDATA[-CH 2 CH 3 ]]> I-4 2 <![CDATA[-CH 2 CH 3 ]]> <![CDATA[-CH 2 CH 3 ]]> <![CDATA[-CH 2 CH 3 ]]> I-5 1 <![CDATA[-CH 3 ]]> <![CDATA[-CH 3 ]]> <![CDATA[-CH=CH 2 ]]> I-6 2 <![CDATA[-CH 3 ]]> <![CDATA[-CH 3 ]]> <![CDATA[-CH=CH 2 ]]> I-7 1 <![CDATA[-CH 3 ]]> <![CDATA[-CH 3 ]]> <![CDATA[-C 6 H 5 ]]> I-8 2 <![CDATA[-CH 3 ]]> <![CDATA[-CH 3 ]]> <![CDATA[-C 6 H 5 ]]> I-9 3 <![CDATA[-CH 3 ]]> <![CDATA[-CH 3 ]]> <![CDATA[-CH 3 ]]> I-10 3 <![CDATA[-CH 2 CH 3 ]]> <![CDATA[-CH 2 CH 3 ]]> <![CDATA[-CH 2 CH 3 ]]> I-11 3 <![CDATA[-CH 3 ]]> <![CDATA[-CH 3 ]]> <![CDATA[-CH=CH 2 ]]> I-12 3 <![CDATA[-CH 3 ]]> <![CDATA[-CH 3 ]]> <![CDATA[-C 6 H 5 ]]>

[0058] 1. Preparation Example

[0059] Preparation Example 1

[0060] Preparation Example 1 provides compound I-1 and its preparation process, comprising the following steps:

[0061]

[0062] S1: In a 500mL reaction bottle equipped with nitrogen protection, mechanical stirring, thermometer, reflux condenser, and tail gas absorption device, add 24.0g (0.25mol) of compound II-1 (hydroxymethylphosphonous acid) and 300mL of dichloromethane, stir evenly, cool to -15°C, add 107.1g (0.9mol) of compound III-1 (thionyl chloride) dropwise, maintain -10 to -8°C, slowly heat to 0°C after the addition, and continue to react for 2h. Concentrate the mother liquor to remove low boiling points, and purify the crude product by column chromatography to obtain 23.4g of compound IV-1.

[0063] In a 500mL reaction bottle equipped with mechanical stirring, thermometer, dropping funnel, reflux condenser and exhaust gas treatment device, add 23.4g (0.075mol) of compound IV-1 prepared in step S1 and 200mL of dichloromethane, cool to -5°C, add 27.0g of water (1.5mol) dropwise, maintain 0-5°C, add the mixture after 3h, warm to room temperature and continue the reaction for 3h, remove low boiling points by distillation under reduced pressure, and obtain 16.8g of compound V-1.

[0064] S2: In a 500mL reaction bottle equipped with a magnetic stirrer, a thermometer, and a reflux condenser, add 16.8g (0.07mol) of compound V-1 prepared in step S1 and 200mL of dichloroethane, stir to disperse thoroughly, cool to -2°C, and drop 25.5g (0.23mol) of 30% hydrogen peroxide solution. After the dropwise addition, keep warm at 0-5°C and continue to react for 4h. Separate the liquids, decontaminate the aqueous phase with sodium bisulfite, distill the organic phase to remove dichloroethane, and purify the crude product by column chromatography to obtain 15.6g of compound VI-1.

[0065] S3: In a 500mL reaction bottle equipped with nitrogen protection, magnetic stirring, thermometer, reflux condenser, and tail gas absorption, add 15.6g (0.06mol) of compound VI-1 prepared in step S2 and 200mL of dichloroethane, stir to dissolve, add 40.9g (0.38mol) of trimethylchlorosilane dropwise at -10℃~-5℃, and after the dropwise addition, raise the temperature to 30℃~35℃ and continue the reaction for 3h. Recover the solvent by water pump vacuum distillation to obtain a crude product, which is purified by column chromatography to obtain 24.9g of compound I-1 with a purity of 99.0%. The total yield of three steps is 34.7% (based on compound II-1).

[0066] Preparation Example 2

[0067] Preparation Example 2 provides compound I-2 and its preparation process, comprising the following steps:

[0068]

[0069]

[0070] S1: In a 500mL reaction bottle equipped with nitrogen protection, mechanical stirring, thermometer, reflux condenser and tail gas absorption device, add 31.5g (0.25mol) of compound II-2 (2-hydroxyethylphosphonic acid) and 300mL of ethyl acetate, stir evenly, first add 15.5g (0.13mol) of compound III-2 (thionyl chloride), then keep the addition rate of thionyl chloride (total amount 1.1mol, 130.9g) unchanged, slowly add 111.3g (1.1mol) of triethylamine, solid gradually appears in the reaction phase, maintain -20~-10℃, slowly raise the temperature to 20℃ after dropping, continue the reaction for 2h, filter to remove solid salt, recover the solvent by vacuum distillation of the mother liquor pump, purify by column chromatography, and obtain 29.8g of compound IV-2. In a 500mL reaction bottle equipped with mechanical stirring, thermometer, dropping funnel, reflux condenser and exhaust gas treatment device, add 29.8g (0.08mol) of compound IV-2 prepared in step S1 and 300mL of dichloromethane, cool to -5°C, add 10.8g of water (0.6mol) dropwise, maintain 0-5°C, add until complete after 3h, warm to room temperature and continue the reaction for 3h, remove the solvent by distillation under reduced pressure to obtain 23.2g of compound V-2.

[0071] S2: In a 500mL reaction bottle equipped with a magnetic stirrer, a thermometer, and a reflux condenser, add 23.2g (0.078mol) of compound V-2 prepared in step S1, 200mL of dichloromethane, stir to disperse thoroughly, cool to -2°C, drop 10.0g (0.09mol) of 30% hydrogen peroxide solution, slowly heat to 15-20°C after dropping, continue to react for 4h, separate, add sodium bisulfite to the aqueous phase to remove excess hydrogen peroxide, and perform harmless treatment. The organic phase, remove dichloromethane by atmospheric distillation, purify by column chromatography, and obtain 19.0g of compound VI-2.

[0072] S3: In a 250ml reaction bottle equipped with nitrogen protection, magnetic stirring, thermometer, reflux condenser, and tail gas absorption device, add 19.0g (0.06mol) of compound VI-2 prepared in step S2 and 96.8g (0.60mol) of hexamethyldisilazane, raise the temperature to 130℃~135℃ and react for 36h, recover the excess hexamethyldisilazane by water pump vacuum distillation, and purify by column chromatography to obtain 25.6g of compound I-2 with a purity of 99.2%. The total yield of three steps is 36.6% (based on compound II-2).

[0073] Preparation Example 3

[0074] Preparation Example 3 provides compound I-6 and its preparation process, comprising the following steps:

[0075]

[0076] S1: In a 500mL reaction bottle equipped with nitrogen protection, mechanical stirring, thermometer, reflux condenser and tail gas absorption device, add 27.5g (0.25mol) of compound II-3 (2-hydroxyethylphosphonous acid), 200mL of toluene, 1.0g of p-toluenesulfonic acid and 15.4g (0.14mol) of dimethyl sulfite, stir and heat to 85-88℃ for 5h, separate the by-product methanol from the water separator, and after the reaction is completed, remove the solvent and low-boiling products by distillation under reduced pressure, and purify the crude product by column chromatography to obtain 21.3g (0.08mol) of compound V-3.

[0077] S2: In a 500mL reaction bottle equipped with a magnetic stirrer, a thermometer, and a reflux condenser, add 21.3g (0.08mol) of compound V-3 prepared in step S1 and 200mL of dichloromethane, stir to disperse thoroughly, cool to -2°C, and add 31.4g (0.28mol) of 30% hydrogen peroxide solution dropwise. After the addition is complete, keep warm at 0-5°C and continue to react for 4h. Separate the liquids, add sodium bisulfite to the aqueous phase to remove excess hydrogen peroxide, and distill the organic phase to remove dichloromethane. The crude product is purified by column chromatography to obtain 20.4g (0.065mol) of compound VI-3.

[0078] S3: In a 500ml reaction bottle equipped with nitrogen protection, magnetic stirring, thermometer, reflux condenser, and tail gas absorption device, add 20.4g (0.065mol) of compound VI-3 prepared in step S2 and 121.2g (0.65mol) of tetramethyldivinyldisilazane, raise the temperature to 130℃~135℃ and react for 40h, recover the excess tetramethyldivinyldisilazane by water pump vacuum distillation, and purify by column chromatography to obtain 31.6g of compound I-6 with a purity of 99.4%. The total yield of three steps is 38.9% (based on compound II-3).

[0079] 2. Test Case

[0080] Lithium-ion battery testing:

[0081] Test Example 1

[0082] Step 1: In a glove box filled with nitrogen or argon with water and oxygen contents ≤ 0.1 ppm, ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed in a volume ratio of 3:7 to obtain a non-aqueous organic solvent mixture, and then lithium hexafluorophosphate is added to dissolve to prepare a solution with a concentration of 1 mol / L, which is the basic electrolyte.

[0083] Step 2: In a glove box filled with nitrogen or argon with water and oxygen contents ≤0.1ppm, add 1% by mass of compound I-1 obtained in Preparation Example 1, 0.5% by mass of VC and 1% by mass of PS to the basic electrolyte, mix well, and obtain the electrolyte to be tested.

[0084] Step 3: In a glove box filled with nitrogen or argon with water and oxygen contents ≤ 0.1 ppm, inject the electrolyte to be tested into the LiNi 0.6 Co 0.2 Mn 0.2 O 2 As the positive electrode material, artificial graphite is used as the negative electrode in the soft pack battery cell. After the injection is completed, the sealing is allowed to stand, the formation is carried out, the aging is carried out, the secondary sealing is carried out, and the capacity is divided.

[0085] Step 4: The lithium-ion battery obtained in this test example is tested for room temperature DC internal resistance, 45°C high temperature cycling, and 60°C high temperature storage.

[0086] Test Example 2

[0087] The operation steps were the same as those of Test Example 1, except that the 1% addition amount of Compound I-1 in Step 2 was replaced by 0.5% addition amount of Compound I-2.

[0088] Test Example 3

[0089] The operation steps are the same as those of Test Example 1, except that the 1% addition amount of Compound I-1 in Step 2 is replaced by 2% addition amount of Compound I-2.

[0090] Test Example 4

[0091] The operation steps are the same as those of Test Example 1, except that the 1% addition amount of Compound I-1 in Step 2 is replaced by 1% addition amount of Compound I-6.

[0092] Comparative Example 1

[0093] The operation steps are the same as those of test example 1, except that there is no step 2.

[0094] Comparative Example 2

[0095] The operation steps are the same as those of Test Example 1, except that compound I-1 is not added in step 2.

[0096] Comparative Example 3

[0097] The operation steps are the same as those of Test Example 1, except that the 1% addition of Compound I-1 in Step 2 is replaced by 1% addition of tris(trimethylsilyl)phosphate.

[0098] Comparative Example 4

[0099] The operation steps are the same as those of Test Example 1, except that the 1% addition of Compound I-1 in Step 2 is replaced by 1% addition of vinyl sulfate.

[0100] Comparative Example 5

[0101] The operation steps are the same as those of Test Example 1, except that the 1% addition of Compound I-1 in Step 2 is replaced by 1% addition of vinyl sulfate and 0.5% addition of tris(trimethylsilyl)phosphate.

[0102] Test Examples 1-4 and Comparative Examples 1-5 were subjected to room temperature DC internal resistance, 45°C high temperature cycle and 60°C high temperature storage tests.

[0103] Room temperature DC internal resistance test: At 25°C, the lithium-ion batteries of test examples 1-4 and comparative examples 1-5 were charged to 4.5V at 1C constant current and constant voltage, with a cut-off current of 0.05C, and then discharged to 3V at 1C constant current, and the discharge capacity Qt was recorded. 1 Then charge to 4.5V at 1C constant current and constant voltage, and fully charge at 0.05C cut-off current, and then discharge 50% Qt at 1C constant current. 1 After standing for 1 hour, record the voltage V 1 , then press 3Qt 1 The current is discharged at a constant current for 10s, and the voltage V after discharge is recorded 2 .

[0104] DC internal resistance (DCR) = (V 1 -V 2 ) / (3*Qt 1 )

[0105] The room temperature DC internal resistance data of test examples 1-4 and comparative examples 1-5 are shown in Table 1 below:

[0106] project DC internal resistance, mΩ Test Example 1 33.43 Test Example 2 34.12 Test Example 3 32.27 Test Example 4 33.98 Comparative Example 1 38.13 Comparative Example 2 39.53 Comparative Example 3 37.32 Comparative Example 4 35.78 Comparative Example 5 35.34

[0107] 45°C high temperature cycle performance test: At 45°C, the lithium ion batteries of Test Examples 1-4 and Comparative Examples 1-5 were charged to 4.5V at 1C constant current, and then discharged to 3V at 1C constant current. After 600 cycles of charge and discharge, the discharge capacity retention rate after the 600th cycle was calculated.

[0108] Discharge capacity retention rate at 45°C (%) = discharge capacity after 600th cycle / discharge capacity after first cycle * 100%

[0109] The 45°C high temperature cycle data of Test Examples 1-4 and Comparative Examples 1-5 are shown in Table 2 below:

[0110]

[0111]

[0112] 60℃ high temperature storage test: At 25℃, the lithium-ion batteries of Test Examples 1-4 and Comparative Examples 1-5 are charged to 4.5V at 0.5C constant current and constant voltage, with a cut-off current of 0.05C, and then discharged to 3V at 0.5C constant current, and the discharge capacity is recorded, which is the initial discharge capacity. Then charge to 4.5V at 0.5C constant current and constant voltage, and test the battery thickness, which is the initial thickness. Place the fully charged battery in a 60℃ constant temperature environment and store for 7 days. Take it out after 7 days, let it stand at 25℃ for 4h, and after the battery cools to room temperature, test the battery thickness, which is the thickness after storage. Discharge to 3V at 0.5C constant current, and record the discharge capacity, which is the retention capacity. Charge to 4.5V at 0.5C constant current and constant voltage, with a cut-off current of 0.05C, and then discharge to 3V at 0.5C constant current, and record the discharge capacity, which is the recovery capacity.

[0113] Battery capacity retention rate (%) = retention capacity / initial capacity * 100%

[0114] Battery capacity recovery rate (%) = recovery capacity / initial capacity * 100%

[0115] Thickness change rate (%) = (thickness after storage - initial thickness) / initial thickness * 100%

[0116] The 60°C high temperature storage data of Test Examples 1-4 and Comparative Examples 1-5 are shown in Table 3 below:

[0117]

[0118]

[0119] It can be seen from Tables 1 to 3 that the electrolyte containing trialkylsilylphosphonate sulfate exhibits lower DC internal resistance, better high-temperature cycle performance and high-temperature storage performance in lithium-ion batteries, and can better inhibit the flatulence of lithium-ion batteries after high-temperature storage.

[0120] Sodium-ion battery testing:

[0121] Test Example 5

[0122] Step 1: In a glove box filled with nitrogen or argon with water and oxygen contents ≤ 0.1 ppm, ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) are mixed in a volume ratio of 3:2:3:2 to obtain a non-aqueous organic solvent mixture, and then sodium hexafluorophosphate is added to dissolve to prepare a solution with a concentration of 1 mol / L, which is the basic electrolyte.

[0123] Step 2: In a glove box filled with nitrogen or argon with water and oxygen contents ≤0.1ppm, add 1% by mass of compound I-1 obtained in Preparation Example 1, 2% by mass of FEC and 1% by mass of PST to the basic electrolyte, mix well, and obtain the electrolyte to be tested.

[0124] Step 3: In a glove box filled with nitrogen or argon with water and oxygen contents ≤ 0.1 ppm, inject the electrolyte to be tested into the NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O 2 As the positive electrode material, hard carbon is used as the negative electrode in the soft pack battery cell. After the liquid is injected, it is sealed and left to stand, formed, aged, resealed, and divided.

[0125] Step 4: The sodium ion battery obtained in this test example is tested for room temperature DC internal resistance, 45°C high temperature cycling, and 60°C high temperature storage.

[0126] Test Example 6

[0127] The operation steps are the same as those of Test Example 5, except that the 1% addition amount of Compound I-1 in Step 2 is replaced by 1% addition amount of Compound I-2.

[0128] Test Example 7

[0129] The operation steps are the same as those of Test Example 5, except that the 1% addition amount of Compound I-1 in Step 2 is replaced by 1% addition amount of Compound I-6.

[0130] Test Case 8

[0131] The operation steps are the same as those of Test Example 5, except that the 1% addition amount of Compound I-1 in Step 2 is replaced by 2% addition amount of Compound I-6.

[0132] Comparative Example 6

[0133] The operation steps are the same as those of test example 5, except that there is no step 2.

[0134] Comparative Example 7

[0135] The operation steps are the same as those of Test Example 5, except that compound I-1 is not added in step 2.

[0136] Comparative Example 8

[0137] The operation steps were the same as those of Test Example 5, except that the 1% addition of Compound I-1 in Step 2 was replaced by 0.5% addition of tris(trimethylsilyl)phosphate.

[0138] Comparative Example 9

[0139] The operation steps are the same as those of Test Example 5, except that the 1% addition of Compound I-1 in Step 2 is replaced by 1% addition of vinyl sulfate.

[0140] Comparative Example 10

[0141] The operation steps are the same as those of Test Example 5, except that the 1% addition of Compound I-1 in Step 2 is replaced by 1% addition of vinyl sulfate and 0.5% addition of tris(trimethylsilyl)phosphate.

[0142] Test Examples 5-8 and Comparative Examples 6-10 were subjected to room temperature DC internal resistance, 45°C high temperature cycle and 60°C high temperature storage tests.

[0143] Room temperature DC internal resistance test: At 25°C, the sodium ion batteries of test examples 5-8 and comparative examples 6-10 were charged to 4V at 1C constant current and constant voltage, with a cut-off current of 0.05C, and then discharged to 2V at 1C constant current, and the discharge capacity Qt was recorded. 2 . Then charge to 4V at 1C constant current and constant voltage, with a cut-off current of 0.05C. Fully charge, and discharge 50% Qt at 1C constant current. 2 After standing for 1 hour, record the voltage V 3 , and then discharge at a constant current of 3Qt for 10s, and record the voltage V after discharge 4 .

[0144] Discharge DC resistance (DCR) = (V 3 -V 4 ) / (3*Qt 2 )

[0145] The room temperature DC internal resistance data of Test Examples 5-8 and Comparative Examples 6-10 are shown in Table 4 below:

[0146]

[0147]

[0148] 45°C high temperature cycle performance test: At 45°C, the sodium ion batteries of Test Examples 5-8 and Comparative Examples 6-10 were charged to 4V at 1C constant current, and then discharged to 2V at 1C constant current. After 200 cycles of charge and discharge, the discharge capacity retention rate after the 200th cycle was calculated.

[0149] Discharge capacity retention rate at 45°C (%) = discharge capacity after 200th cycle / discharge capacity after first cycle * 100%

[0150] The 45°C high temperature cycle data of Test Examples 5-8 and Comparative Examples 6-10 are shown in Table 5 below:

[0151] project 45℃ discharge capacity retention rate, % Test Example 5 83.45 Test Example 6 81.34 Test Example 7 84.23 Test Case 8 85.85 Comparative Example 6 64.98 Comparative Example 7 68.47 Comparative Example 8 70.12 Comparative Example 9 76.75 Comparative Example 10 76.12

[0152] 60℃ high temperature storage test: At 25℃, the sodium ion batteries of Test Examples 5-8 and Comparative Examples 6-10 are charged to 4V at 0.5C constant current and constant voltage, with a cut-off current of 0.05C, and then discharged to 2V at 0.5C constant current, and the discharge capacity is recorded, which is the initial discharge capacity. Then charge to 4V at 0.5C constant current and constant voltage, and test the battery thickness, which is the initial thickness. Place the fully charged battery in a 60℃ constant temperature environment and store for 7 days. Take it out after 7 days, let it stand at 25℃ for 4h, and after the battery cools to room temperature, test the battery thickness, which is the thickness after storage. Discharge to 2V at 0.5C constant current, and record the discharge capacity, which is the retention capacity. Charge to 4V at 0.5C constant current and constant voltage, with a cut-off current of 0.05C, and then discharge to 2V at 0.5C constant current, and record the discharge capacity, which is the recovery capacity.

[0153] Battery capacity retention rate (%) = retention capacity / initial capacity * 100%

[0154] Battery capacity recovery rate (%) = recovery capacity / initial capacity * 100%

[0155] Thickness change rate (%) = (thickness after storage - initial thickness) / initial thickness * 100%

[0156] The 60°C high temperature storage data of Test Examples 5-8 and Comparative Examples 6-10 are shown in Table 6 below:

[0157]

[0158]

[0159] It can be seen from Tables 4 to 6 that the electrolyte containing trialkylsilylphosphonate sulfate also exhibits lower DC internal resistance, better high-temperature cycle performance and high-temperature storage performance in sodium-ion batteries, and also inhibits flatulence of sodium-ion batteries after high-temperature storage.

[0160] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. The above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A secondary battery electrolyte containing trihydrocarbylsilylphosphonate sulfate, characterized in that: The electrolyte comprises trialkylsilylphosphonate sulfate, electrolyte salt, non-aqueous organic solvent and other additives.

2. A trialkylsilylphosphonate sulfate according to claim 1, characterized in that: The general structural formula of the compound I is as follows: Wherein, n≥1, and n is preferably 1, 2, or 3; R1, R2, and R3 are selected from C1-C6 hydrocarbon groups, and are preferably one of cyano hydrocarbon groups and fluorine-containing hydrocarbon groups.

3. A trialkylsilylphosphonate sulfate according to claim 2, characterized in that: The preparation process of the compound I is divided into three steps: S1: Compound II reacts with compound III, and when X in compound III-a is selected from Br or Cl, compound IV is obtained; compound IV is hydrolyzed to obtain compound V; the reaction formula is as follows: Wherein, R is selected from a hydrogen atom or a C1-C4 alkyl group; n≥1, and n is preferably 1, 2, or 3; and m is 0 or 1; Compound II reacts with compound III, and Y in compound III-b is selected from a C1-C4 alkyl group, and no hydrolysis step is required to directly obtain compound V. The reaction formula is as follows: S2: Compound V is oxidized to obtain compound VI, and reaction formula II is as follows: S3: Compound VI reacts with a trialkylsilyl compound to obtain a final product, Compound I, and reaction formula III is as follows:

4. A process for preparing trialkylsilylphosphonate sulfate according to claim 3, characterized in that: In the step S1, the compound III-a is preferably thionyl chloride, and the compound III-b is preferably one of dimethyl sulfite and diethyl sulfite; the molar ratio of compound III to compound II is 2.0 to 5.0:1, and the preferred molar ratio is 2.5 to 4.0:1; the reaction temperature is -20 to 40°C, and the preferred reaction temperature is -10 to 20°C.

5. The process for preparing trialkylsilylphosphonate sulfate according to claim 4, characterized in that: In the step S1, the solvent used in the reaction of compound II with compound III is at least one of alkanes, halogenated hydrocarbons, esters, and sulfones, specifically, at least one selected from benzene, toluene, xylene, cyclohexane, cyclopentane, dichloromethane, chloroform, ethyl acetate, butyl acetate, dimethyl carbonate, diethyl carbonate, dimethyl sulfoxide, and sulfolane.

6. The process for preparing trialkylsilylphosphonate sulfate according to claim 3, characterized in that: In the step S2, compound V is oxidized to obtain compound VI, and the oxidant used is selected from one of hydrogen peroxide, ozone, hypochlorous acid, oxygen, air, sodium hypochlorite, ammonium persulfate, potassium persulfate, potassium hydrogen persulfate, peroxysulfuric acid, sodium percarbonate, sodium perchlorate, sodium periodate, manganese oxide, and potassium permanganate. The preferred oxidants are hydrogen peroxide, sodium hypochlorite, and potassium hydrogen persulfate.

7. The process for preparing trialkylsilylphosphonate sulfate according to claim 6, characterized in that: In the step S2, the reaction solvent is selected from an organic solvent or water, preferably an organic solvent; the molar ratio of the active oxygen provided by the oxidant to the compound V is 3.0 to 6.0:1, preferably 3.6 to 4.0:1; and the reaction temperature is -20 to 60°C.

8. The process for preparing trialkylsilylphosphonate sulfate according to claim 3, characterized in that: In the step S3, compound VI reacts with a trialkylsilyl compound to obtain a final product compound I, wherein the trialkylsilyl compound is selected from one of trialkylsilazane, trialkylsiloxane or trialkylhalosilane; preferably, the trialkylsilyl compound is selected from hexaalkyldisilazane, hexaalkyldisiloxane, heptaalkyldisilazane, trialkylchlorosilane, trialkyloxysilane, trialkylacyloxysilane, trialkylsilylamine, trialkylsilylimidazole, trialkylamineoxysilane, trialkylalkenyloxysilane. , trialkyloxime silane or N, O-bistrimethylsilyl acetamide; more typically selected from at least one of trimethylchlorosilane, hexamethyldisilazane, heptamethyldisilazane, tetramethyldivinyldisilazane, trimethylmethoxysilane, trimethylethoxysilane, trimethylsilylimidazole, hexamethyldisilurea or N, O-bistrimethylsilyl acetamide, tetramethylbis(trifluoromethyl)disiloxane, tetraisopropyldicyanodisiloxane, tetramethyl-bis(3-cyanopropyl)disilazane.

9. The process for preparing trialkylsilylphosphonate sulfate according to claim 8, characterized in that: In the step S3, the molar ratio of the trialkylsilyl compound to compound VI is 2 to 20:1, preferably 4.5 to 12:1; the reaction temperature is -10 to 160°C, and the reaction time is 1 to 40 hours.

10. The secondary battery electrolyte according to claim 1, characterized in that: The other additives are selected from at least one of vinylene carbonate (VC), vinyl vinyl carbonate (VEC), fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), vinyl sulfite (ES), methylene methanedisulfonate (MMDS), 1,3-propane sultone (PS), 1,3-propylene sultone (PST), tris(trimethylsilyl) phosphite (TMSPi), tris(trimethylsilyl) borate (TMSB), succinic anhydride (SA), succinonitrile (SN), adiponitrile (ADN), and ethoxypentafluorocyclotriphosphazene (PFPN).

11. The secondary battery electrolyte according to claim 1, characterized in that: Based on 100% of the total mass of the electrolyte, the amount of the trialkylsilylphosphonate sulfate compound additive added is 0.1% to 5%, and the amount of other additives added is 0.1% to 5%.

12. The secondary battery electrolyte according to claim 1, characterized in that: When the secondary battery is a lithium ion battery, the electrolyte in the electrolyte is one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium difluorophosphate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(oxalatoborate), lithium difluorooxalatoborate, lithium tetrafluorooxalatophosphate, lithium difluorobis(oxalatophosphate), and lithium fluorosulfonyl(trifluoromethylsulfonyl)imide, and the molar concentration of the electrolyte in the electrolyte is 0.5 to 2 mol / L; when the secondary battery is a sodium ion battery, the electrolyte in the electrolyte is sodium hexafluorophosphate, sodium difluorophosphate, sodium bis(oxalatoborate), and sodium di(trifluoromethylsulfonyl)imide. At least one of sodium fluorooxalatoborate, sodium bis(trifluoromethylsulfonylimide), sodium bis(trifluoromethylsulfonylimide), sodium trifluoromethylsulfonate, sodium perchlorate, and sodium tetrafluoroborate; the non-aqueous organic solvent is composed of one or more of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethylene carbonate, ethyl methyl carbonate, methyl propyl carbonate, methyl butyl carbonate, propylene carbonate, γ-butyrolactone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, difluoroethyl acetate, trifluoroethyl acetate, trifluoroethyl methyl carbonate, and bis(trifluoroethyl carbonate).

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