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Preparation method of lithium difluorophosphate

A technology of lithium difluorophosphate and lithium hexafluorophosphate, which is applied in chemical instruments and methods, phosphorus compounds, secondary batteries, etc., can solve the problems of high preparation cost of lithium difluorophosphate, difficulty in purifying lithium difluorophosphate, and difficult control of the reaction process. , to achieve the effect of being beneficial to actual operation, slowing down, and easy to separate

Active Publication Date: 2021-04-02
DONGGUAN DONGYANG SOLAR SCI RES & DEV CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Chinese patent application CN101507041A discloses a preparation method of lithium difluorophosphate, which includes reacting lithium hexafluorophosphate with a substance with a Si-O-Si structure. This reaction needs to be carried out under heating, and is prone to violent gas generation. The cost of similar substances is high and it is difficult to carry out large-scale production
Chinese patent application CN108128764A discloses a method for rapidly preparing lithium difluorophosphate, which includes adding lithium hexafluorophosphate to the purified ester solvent, using ultrapure water as a catalyst, adding high-purity lithium carbonate, and reacting to prepare lithium difluorophosphate. However, the reaction process in this process is not easy to control, and there are many by-products, which bring difficulties to the subsequent purification of lithium difluorophosphate
Chinese patent CN108640096A discloses that difluorophosphoric acid and lithium source substances are reacted in a non-aqueous solvent to obtain lithium difluorophosphate, but the product still needs to go through a purification process to obtain high-quality lithium difluorophosphate products
[0004] To sum up, the preparation method of lithium difluorophosphate in the prior art either requires heating operation, or the reaction process is cumbersome, or the purification process is complicated, resulting in a relatively high overall preparation cost of lithium difluorophosphate

Method used

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  • Preparation method of lithium difluorophosphate
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  • Preparation method of lithium difluorophosphate

Examples

Experimental program
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Effect test

Embodiment 1

[0037] Prepare a 1L two-neck flask, put it in the glove box, add 300mL dimethyl carbonate, weigh 50g LiPF 6 , which was slowly added into dimethyl carbonate, and the flask was taken out after stirring for 2 h. Place it on a magnetic stirrer, then weigh 40.8g of ammonium oxalate, quickly add it to the flask, and then measure 21mL of SiCl 4 , quickly transferred to the flask, and the reaction occurred immediately. At this time, after replacing the air in the flask with nitrogen, connect the tail gas absorption device, and react at room temperature for 8 hours, almost no bubbles emerge, and the reaction ends. Filter to obtain a filter cake containing lithium difluorophosphate and ammonium chloride, add the filter cake to a flask containing 400 mL of ethyl acetate, and stir at room temperature for 4 h. Then filter to obtain an ethyl acetate solution containing only lithium difluorophosphate. Distill the solution under reduced pressure at 50°C. When concentrated under reduced pre...

Embodiment 2

[0039] Prepare a 1L two-neck flask, put it in the glove box, add 300mL of dichloromethane, weigh 50g of LiPF 6, which was slowly added to dichloromethane, and the flask was taken out after stirring for 2 h. Place it on a magnetic stirrer, then weigh 40.8g of ammonium oxalate, quickly add it to the flask, and then measure 21mL of SiCl 4 , quickly transferred to the flask, and the reaction occurred immediately. At this time, after replacing the air in the flask with nitrogen, connect the tail gas absorption device, and react at room temperature for 8 hours, almost no bubbles emerge, and the reaction ends. Filter to obtain a filter cake containing lithium difluorophosphate and ammonium chloride, add the filter cake to a flask containing 380 mL of ethyl acetate, and stir at room temperature for 5 h. Then filter to obtain an ethyl acetate solution containing only lithium difluorophosphate, distill the solution under reduced pressure at 50°C, and concentrate under reduced pressure...

Embodiment 3

[0041] Prepare a 2L three-neck flask, put it in the glove box, add 800mL toluene, and weigh 100g LiPF 6 , which was slowly added to toluene, and the flask was taken out after stirring for 3 h. Place it on a magnetic stirrer, then weigh 131g of potassium oxalate, quickly add it to the flask, and then measure 46mL of SiCl 4 , quickly transferred to the flask, and the reaction occurred immediately. At this time, after replacing the air in the flask with nitrogen, connect the tail gas absorption device, and react at room temperature for 20 hours, almost no bubbles emerge, and the reaction ends. Filter to obtain a filter cake containing lithium difluorophosphate and potassium chloride, add the filter cake to a flask containing 850 mL of methanol, and stir at room temperature for 3 h. Then filter to obtain a methanol solution containing only lithium difluorophosphate, distill the solution under reduced pressure at 60°C, concentrate under reduced pressure to just saturated state, t...

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Abstract

The invention relates to a preparation method of lithium difluorophosphate. The preparation method comprises the steps: reacting lithium hexafluorophosphate, oxalate and silicon tetrachloride in an organic solvent, wherein the reaction is carried out in a protective atmosphere, and the molar ratio of the lithium hexafluorophosphate to the oxalate to the silicon tetrachloride is 1:(1-1.5):(0.55-0.75). According to the preparation method, lithium difluorophosphate can be simply, conveniently and efficiently synthesized at room temperature, and a high-purity lithium difluorophosphate product meeting the use requirements of a battery electrolyte can be obtained through simple treatment after reaction. The preparation method provided by the invention has the advantages of low preparation cost,simple reaction flow, strong operability, suitability for industrial production and the like.

Description

technical field [0001] The invention relates to the technical field of chemical synthesis, in particular to a preparation method of lithium difluorophosphate. Background technique [0002] Lithium-ion battery electrolyte mainly adopts organic carbonate solution of lithium hexafluorophosphate, supplemented by various functional additives, but the decomposition and side reactions of the electrolyte during the use of the battery will affect its durability such as cyclability and high-temperature storage. Therefore, various electrolyte additives with excellent performance have been gradually developed and used to inhibit the decomposition of the electrolyte on the surface of the active electrode and prevent deterioration. Studies have shown that the lithium difluorophosphate additive can significantly improve the cycle performance of the battery, which has gradually attracted the attention and attention of the lithium-ion battery industry. [0003] Japanese patent application J...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/455H01M10/0567
CPCC01B25/455H01M10/0567C01P2006/80Y02E60/10
Inventor 冯天明余意何凤荣
Owner DONGGUAN DONGYANG SOLAR SCI RES & DEV CO LTD
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