Preparation method of lithium difluorobisoxalate phosphate solution

Abstract

The invention provides a preparation method of a lithium difluorobisoxalate phosphate solution. The preparation method of the lithium difluorobisoxalate phosphate solution comprises the following steps that (1) dichlorodimethylsilane and oxalic acid are reacted in the presence of a non-aqueous solvent to generate dimethyl silicon-based oxalate; and (2) lithium hexafluorophosphate is added into thereaction solution in the step (1), and reacting is carried out to obtain the lithium difluorobisoxalate phosphate solution. The preparation method is simple and practical, and industrial production can be achieved; the prepared lithium difluorobisoxalate phosphate solution can be directly used as an additive of a non-aqueous electrolyte battery; and the prepared lithium difluorobisoxalate phosphate solution has few chlorine compounds and free acids, wherein the chlorine compounds in terms of chlorine concentration are less than 5 mass ppm, and the free acids in terms of acid concentration converted from hydrofluoric acid are less than 200 mass ppm.

Description

technical field

[0001] The invention belongs to the field of lithium ion batteries, and in particular relates to a preparation method of lithium difluorobisoxalate phosphate solution. Background technique

[0002] Lithium difluorobisoxalate phosphate is used as an additive for nonaqueous electrolyte batteries such as lithium ion batteries and lithium ion capacitors. After the additive is added to the electrolyte, the battery has excellent low temperature resistance, and can form a stable solid electrolyte interfacial film on the surface of the positive and negative electrodes of the battery, improving the cycle performance of the battery. In addition, as a production method of lithium difluorobisoxalate phosphate, there are mainly the following forms.

[0003] Patent No. CN200980145463 proposes to mix oxalic acid and lithium hexafluorophosphate in a certain molar ratio, and then add SiCl to it 4 The method by which the reaction occurs. In this method, due to the use of hi...

Examples

Embodiment 1

[0034] In a nitrogen glove box with a moisture content of less than 20 mass ppm, prepare a 1000ml three-neck flask containing a stirring bar, and add 500 g of diethyl carbonate with a moisture content of 10 mass ppm or less and 20.0 g of oxalic acid with a moisture content of 200 mass ppm into a three-necked flask, and seal the three-necked flask. Transfer the aforementioned three-necked flask to the outside of the glove box, put it in an oil bath at a temperature of 65°C, install a condenser tube, a constant pressure dropping funnel, insert a bubbler and use nitrogen gas to bubble slowly, and the bulging gas is absorbed by water . Using a magnetic stirrer, stir the solution well until a homogeneous solution is formed.

[0035] Next, 43 g of dichlorodimethylsilane was added into the constant pressure dropping funnel, and the dichlorodimethylsilane was dropped into the homogeneous solution in the three-necked flask for 30 minutes. After the dropwise addition, the constant pre...

Embodiment 2

[0041] Using 51.6 g of dichlorodimethylsilane, the molar ratio to oxalic acid is 1.8, and the non-aqueous solvent uses dimethyl carbonate, except that it is synthesized in the same manner as in Example 1, and is carried out in the same manner as in Example 1 19 Determination of F NMR, determination of chloride ion concentration, determination of free acid concentration. The product concentration in the solution calculated by NMR was 3.9% by mass, and the yield of lithium difluorobisoxalate phosphate calculated by lithium hexafluorophosphate was 75%. The chloride ion concentration was 4.9 mass ppm, and the hydrofluoric acid was 142 mass ppm.

Embodiment 3

[0043] Using 37.3 g of dichlorodimethylsilane, the molar ratio to oxalic acid is 1.3, and the non-aqueous solvent uses dimethyl carbonate, except that it is synthesized in the same manner as in Example 1, and is carried out in the same manner as in Example 119 F NMR determination, chloride ion concentration determination, free acid concentration determination. The product concentration in the solution calculated by NMR was 3.9% by mass, and the yield of lithium difluorobisoxalate phosphate was 76% based on lithium hexafluorophosphate. The chloride ion concentration was 1.4 mass ppm, and the hydrofluoric acid was 89 mass ppm.

technical field

[0001] The invention belongs to the field of lithium ion batteries, and in particular relates to a preparation method of lithium difluorobisoxalate phosphate solution. Background technique

[0002] Lithium difluorobisoxalate phosphate is used as an additive for nonaqueous electrolyte batteries such as lithium ion batteries and lithium ion capacitors. After the additive is added to the electrolyte, the battery has excellent low temperature resistance, and can form a stable solid electrolyte interfacial film on the surface of the positive and negative electrodes of the battery, improving the cycle performance of the battery. In addition, as a production method of lithium difluorobisoxalate phosphate, there are mainly the following forms.

[0003] Patent No. CN200980145463 proposes to mix oxalic acid and lithium hexafluorophosphate in a certain molar ratio, and then add SiCl to it 4 The method by which the reaction occurs. In this method, due to the use of hi...

Examples

Embodiment 1

[0034] In a nitrogen glove box with a moisture content of less than 20 mass ppm, prepare a 1000ml three-neck flask containing a stirring bar, and add 500 g of diethyl carbonate with a moisture content of 10 mass ppm or less and 20.0 g of oxalic acid with a moisture content of 200 mass ppm into a three-necked flask, and seal the three-necked flask. Transfer the aforementioned three-necked flask to the outside of the glove box, put it in an oil bath at a temperature of 65°C, install a condenser tube, a constant pressure dropping funnel, insert a bubbler and use nitrogen gas to bubble slowly, and the bulging gas is absorbed by water . Using a magnetic stirrer, stir the solution well until a homogeneous solution is formed.

[0035] Next, 43 g of dichlorodimethylsilane was added into the constant pressure dropping funnel, and the dichlorodimethylsilane was dropped into the homogeneous solution in the three-necked flask for 30 minutes. After the dropwise addition, the constant pre...

Embodiment 2

[0041] Using 51.6 g of dichlorodimethylsilane, the molar ratio to oxalic acid is 1.8, and the non-aqueous solvent uses dimethyl carbonate, except that it is synthesized in the same manner as in Example 1, and is carried out in the same manner as in Example 1 19 Determination of F NMR, determination of chloride ion concentration, determination of free acid concentration. The product concentration in the solution calculated by NMR was 3.9% by mass, and the yield of lithium difluorobisoxalate phosphate calculated by lithium hexafluorophosphate was 75%. The chloride ion concentration was 4.9 mass ppm, and the hydrofluoric acid was 142 mass ppm.

Embodiment 3

[0043] Using 37.3 g of dichlorodimethylsilane, the molar ratio to oxalic acid is 1.3, and the non-aqueous solvent uses dimethyl carbonate, except that it is synthesized in the same manner as in Example 1, and is carried out in the same manner as in Example 119 F NMR determination, chloride ion concentration determination, free acid concentration determination. The product concentration in the solution calculated by NMR was 3.9% by mass, and the yield of lithium difluorobisoxalate phosphate was 76% based on lithium hexafluorophosphate. The chloride ion concentration was 1.4 mass ppm, and the hydrofluoric acid was 89 mass ppm.

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