A method for preparing tris(trimethylsilyl)phosphate

Abstract

The present invention provides a preparation method of tris(trimethylsilyl)phosphate, belonging to the technical field of battery electrolyte additives, wherein the preparation method is that trimethylchlorosilane and ammonium dihydrogen phosphate are added to N,N-dimethylformamide under the protection of an inert gas, and reacted at room temperature under the action of a catalyst to obtain the tris(trimethylsilyl)phosphate. The present invention uses trimethylchlorosilane and ammonium dihydrogen phosphate as raw materials, reacts by selecting a suitable solvent and a catalyst to cooperate with each other, and effectively improves the yield of tris(trimethylsilyl)phosphate.

Description

Technical Field

[0001] The invention relates to the technical field of battery electrolyte additives, in particular to a method for preparing tris(trimethylsilyl)phosphate. Background Art

[0002] Tris(trimethylsilyl)phosphite and phosphate can be used as electrolyte additives for lithium-ion batteries to improve the performance of lithium-ion batteries. Compositions and polymer electrolytes that can inhibit the reduction of battery capacity during the charging and storage state of lithium-ion batteries.

[0003] The Chinese patent document with publication number CN101217204A points out that when a non-aqueous electrolyte contains both sultone with an unsaturated hydrocarbon group and tris(trimethylsilyl)phosphate, a low-resistance coating can be formed on the surface of the negative electrode without reducing the high-current performance of the battery, thereby greatly suppressing the self-discharge of the battery and improving the cycle performance of the battery. The battery containing this electrolyte can be used as a power battery in electric vehicles.

[0004] A Chinese patent document with publication number CN101870711A proposes a method for industrial production: at 80-160°C, hexamethyldisilazane reacts with ammonium dihydrogen phosphate for 2-5 hours to generate tris(trimethylsilyl)phosphate and ammonia, and then the crude product is distilled and purified to obtain tris(trimethylsilyl)phosphate. However, the reaction temperature of this method is high, hexamethyldisilazane is 50% excessive, the dosage is large, and the molar yield of the product is below 80%, so the production cost is high. Summary of the invention

[0005] In view of the above problems, the present invention provides a method for preparing tris(trimethylsilyl)phosphate.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is:

[0007] A method for preparing tris(trimethylsilyl)phosphate, wherein trimethylchlorosilane and ammonium dihydrogen phosphate are added to N,N-dimethylformamide under the protection of an inert gas, and reacted at room temperature under the action of a catalyst to obtain the tris(trimethylsilyl)phosphate. The specific chemical reaction formula is as follows:

[0008]

[0009] Furthermore, the preparation method is to dissolve trimethylchlorosilane in N,N-dimethylformamide under the protection of an inert gas, add diammonium phosphate in batches, and then add a catalyst, react at room temperature, and after the reaction is completed, filter and concentrate, and add a toluene-petroleum ether mixture to the obtained concentrate for recrystallization to obtain the tri(trimethylsilyl)phosphate.

[0010] Furthermore, in the toluene-petroleum ether mixture, the volume ratio of toluene to petroleum ether is 1:3-4.

[0011] Furthermore, the volume ratio of the concentrate to the toluene-petroleum ether mixture is 1:6-7.

[0012] Furthermore, the catalyst is tetrabutylammonium chloride or tetrabutylammonium bromide.

[0013] Furthermore, the molar ratio of trimethylsilyl chloride to diammonium phosphate is 3.1-3.2:1.

[0014] Furthermore, the weight volume ratio of ammonium dihydrogen phosphate to N,N-dimethylformamide is 1 g:6-8 mL.

[0015] Furthermore, the weight ratio of diammonium phosphate to the catalyst is 1:0.05-0.10.

[0016] The beneficial effects of the preparation method of tris(trimethylsilyl)phosphate of the present invention are:

[0017] The invention uses trimethylsilyl chloride and ammonium dihydrogen phosphate as raw materials, selects a suitable solvent and a catalyst to cooperate with each other for reaction, and effectively improves the yield of tris(trimethylsilyl)phosphate; the invention uses trimethylsilyl chloride and ammonium dihydrogen phosphate as raw materials, and the generated ammonium chloride and hydrogen chloride can be directly removed by concentration, and recrystallized by a toluene-petroleum ether mixed liquid, thereby simplifying the post-treatment process; the overall process method of the invention is simple and easy to operate, the product yield and purity are both high, and the reaction conditions are mild, no harsh production conditions are required, and the invention is suitable for industrial production. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention are described clearly and completely below. In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0019] Example 1 A method for preparing tris(trimethylsilyl)phosphate

[0020] This embodiment is a method for preparing tris(trimethylsilyl)phosphate, and the specific preparation process includes the following steps performed in sequence:

[0021] Toluene and petroleum ether are mixed in a volume ratio of 1:3.5 to obtain a toluene-petroleum ether mixed liquid;

[0022] Under nitrogen protection, 33.68g (0.31mol) of trimethylsilyl chloride was dissolved in 70mL of N,N-dimethylformamide, 11.50g (0.1mol) of ammonium dihydrogen phosphate was added in 5 batches, and then 1.00g of tetrabutylammonium chloride was added, and the reaction was carried out at room temperature. After the reaction was completed, it was filtered and concentrated under reduced pressure. The concentrate was added with 6.5 times the weight of toluene-petroleum ether mixed solution for recrystallization to obtain 30.57g of tris (trimethylsilyl) phosphate, with a yield of 97.20% and a purity of 99.97%. The specific chemical reaction formula is as follows:

[0023]

[0024] Example 2 A method for preparing tris(trimethylsilyl)phosphate

[0025] This embodiment is a method for preparing tris(trimethylsilyl)phosphate, and the specific preparation process includes the following steps performed in sequence:

[0026] Toluene and petroleum ether are mixed in a volume ratio of 1:4 to obtain a toluene-petroleum ether mixed liquid;

[0027] Under nitrogen protection, 34.22 g (0.315 mol) of trimethylsilyl chloride was dissolved in 69 mL of N, N-dimethylformamide, 11.50 g (0.1 mol) of ammonium dihydrogen phosphate was added in 5 batches, and then 0.575 g of tetrabutylammonium bromide was added. The reaction was carried out at room temperature. After the reaction was completed, it was filtered and concentrated under reduced pressure. The concentrate was added with 7 times the weight of toluene-petroleum ether mixture for recrystallization to obtain 30.57 g of tris(trimethylsilyl) phosphate with a yield of 96.22% and a purity of 99.94%.

[0028] Example 3 Preparation method of tris(trimethylsilyl)phosphate

[0029] This embodiment is a method for preparing tris(trimethylsilyl)phosphate, and the specific preparation process includes the following steps performed in sequence:

[0030] Toluene and petroleum ether are mixed in a volume ratio of 1:3 to obtain a toluene-petroleum ether mixed liquid;

[0031] Under nitrogen protection, 34.76g (0.32mol) of trimethylsilyl chloride was dissolved in 92mL of N,N-dimethylformamide, and 11.50g (0.1mol) of ammonium dihydrogen phosphate was added in 5 batches, and then 1.15g of tetrabutylammonium bromide was added. The reaction was carried out at room temperature. After the reaction was completed, it was filtered and concentrated under reduced pressure. The concentrate was added with 6 times the weight of toluene-petroleum ether mixture for recrystallization to obtain 30.60g of tris(trimethylsilyl) phosphate with a yield of 97.30% and a purity of 99.95%.

[0032] Example 4 A method for preparing tris(trimethylsilyl)phosphate

[0033] This embodiment is a method for preparing tris(trimethylsilyl)phosphate, and the specific preparation process includes the following steps performed in sequence:

[0034] Toluene and petroleum ether are mixed in a volume ratio of 1:3.5 to obtain a toluene-petroleum ether mixed liquid;

[0035] Under nitrogen protection, 34.76g (0.32mol) of trimethylsilyl chloride was dissolved in 80mL of N,N-dimethylformamide, and 11.50g (0.1mol) of ammonium dihydrogen phosphate was added in 5 batches, and then 0.9g of tetrabutylammonium bromide was added. The reaction was carried out at room temperature. After the reaction was completed, it was filtered and concentrated under reduced pressure. The concentrate was added with 6.5 times the weight of toluene-petroleum ether mixture for recrystallization to obtain 30.43g of tris(trimethylsilyl) phosphate, with a yield of 96.76% and a purity of 99.97%.

[0036] Example 5 A method for preparing tris(trimethylsilyl)phosphate

[0037] This embodiment is a method for preparing tris(trimethylsilyl)phosphate, and the specific preparation process includes the following steps performed in sequence:

[0038] Toluene and petroleum ether are mixed in a volume ratio of 1:4 to obtain a toluene-petroleum ether mixed liquid;

[0039] Under nitrogen protection, 33.68g (0.31mol) of trimethylsilyl chloride was dissolved in 75mL of N,N-dimethylformamide, and 11.50g (0.1mol) of ammonium dihydrogen phosphate was added in 5 batches, and then 0.8g of tetrabutylammonium bromide was added. The reaction was carried out at room temperature. After the reaction was completed, it was filtered and concentrated under reduced pressure. The concentrate was added with 6.5 times the weight of toluene-petroleum ether mixture for recrystallization to obtain 30.34g of tris(trimethylsilyl) phosphate with a yield of 96.47% and a purity of 99.95%.

[0040] Comparative Example 1

[0041] Common tris(trimethylsilyl)phosphate finished products on the market were purchased, and 5 groups of finished products were selected by random sampling. The purity was measured by high performance liquid chromatography, and the average purity was 98.1%.

[0042] The purity of the finished products of Examples 1 to 6 was compared with the product yield and purity of Comparative Example 1, and the comparison results are shown in Table 1.

[0043] Table 1

[0044] project Yield (%) purity(%) Example 1 97.20 99.97 Example 2 96.22 99.94 Example 3 97.30 99.95 Example 4 96.76 99.97 Example 5 96.47 99.95 Comparative Example 1 / 98.1

[0045] Application experiment:

[0046] The ternary material NCM (622) lithium is used as the positive electrode material, the negative electrode uses mesophase carbon microspheres, the positive and negative current collectors are distributed as aluminum foil and copper foil, and the diaphragm uses a ceramic diaphragm to form a soft-pack battery. After injecting the electrolyte, it is assembled into a soft-pack battery in a glove box and tested after standing for 8 hours. The battery is activated by charging and discharging at 1 / 10C 3.0V to 4.2V or above at a constant temperature of 25°C to obtain the battery to be tested. The electrolytes tested include basic electrolyte E1 and electrolyte E2, and their compositions are as follows:

[0047] 1. Basic electrolyte E1

[0048] EC: Solution-1: DEC=3:3:4(v:v:v), LiPF6: 1.0M, 0.5% LiFSI, 1%VC

[0049] 2. Electrolyte E2

[0050] EC: Solution-1: DEC = 3:3:4 (v:v:v), LiPF6: 1.0M, 0.5% LiFSI, 1% VC, 1% tris(trimethylsilyl) phosphate additive

[0051] Test results:

[0052] 1. The test results after 60℃ cycle are as follows:

[0053] Table 2

[0054]

[0055] 2. Place the battery in a low temperature box, control the temperature to -30℃ or -40℃, and place it in a low temperature box for 240 minutes, then measure the battery capacity retention rate.

[0056] Table 3

[0057]

[0058] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing tris(trimethylsilyl)phosphate, characterized in that: The preparation method is to add trimethylchlorosilane and ammonium dihydrogen phosphate to N,N-dimethylformamide under the protection of inert gas, and react at room temperature under the action of a catalyst to obtain the tris(trimethylsilyl)phosphate. The specific chemical reaction formula is as follows: The preparation method is to dissolve trimethylsilyl chloride in N,N-dimethylformamide under the protection of inert gas, add ammonium dihydrogen phosphate in batches, and then add a catalyst to react at room temperature. After the reaction is completed, the mixture is filtered and concentrated, and the obtained concentrate is added to a toluene-petroleum ether mixture for recrystallization to obtain the tris(trimethylsilyl)phosphate; The catalyst is tetrabutylammonium chloride or tetrabutylammonium bromide; The weight ratio of diammonium phosphate to the catalyst is 1:0.05-0.

10.

2. The method for preparing tris(trimethylsilyl)phosphate according to claim 1, characterized in that: In the toluene-petroleum ether mixed liquid, the volume ratio of toluene to petroleum ether is 1:3-4.

3. The method for preparing tris(trimethylsilyl)phosphate according to claim 1 or 2, characterized in that: The volume ratio of the concentrate to the toluene-petroleum ether mixed liquid is 1:6-7.

4. The method for preparing tris(trimethylsilyl)phosphate according to any one of claims 1 to 2, characterized in that: The molar ratio of trimethylsilyl chloride to diammonium phosphate is 3.1-3.2:

1.

5. The method for preparing tris(trimethylsilyl)phosphate according to any one of claims 1 to 2, characterized in that: The weight volume ratio of ammonium dihydrogen phosphate to N,N-dimethylformamide is 1g:6-8mL.

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