Synthesis method of lithium difluorophosphate

A technology of lithium difluorophosphate and its synthesis method, which is applied in the direction of phosphorus compounds, chemical instruments and methods, and secondary batteries, etc., and can solve the problem that trimethyltin fluoride is difficult to obtain, it is difficult to separate lithium fluoride impurities, and it is difficult to obtain high Purity products and other issues, to achieve the effect of low moisture and free chlorine value, solve the difficulty of product extraction, and high product purity

Active Publication Date: 2017-06-23
山东永浩新材料科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] 1) with Li 2 CO 3 and LiPF 6 Or phosphorus pentafluoride reacts to prepare lithium difluorophosphate, which will produce lithium fluoride impurities that are difficult to separate;
[0005] 2) with P 4 o 10 Solid-solid reaction with LiF to synthesize lithium difluorophosphate, the reaction is not easy to control, with many by-products and low yield;
[0007] 4) Using LiPF 6 Lithium difluorophosphate is prepared by hydrolysis. This reaction is not easy to control and will produce LiPO 4 F, HF, HPO 2 f 2 Impurities that affect battery performance, and are not easy to purify, it is difficult to obtain high-purity products;
[0008] 5) Lithium difluorophosphate was prepared by displacement reaction of organotin fluoride and lithium dichlorophosphate, but the raw material trimethyltin fluoride is not easy to obtain

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] In a closed stainless steel reaction kettle, P 2 o 5 , LiF and dry tetrahydrofuran were added to the reaction kettle, sealed and stirred, cooled to -40°C, and the atmosphere in the kettle was replaced with nitrogen, argon or helium with a water content of less than 1ppm three times. After the water content in the kettle was less than 1ppm, the temperature was raised to 100 ℃, pressurize to 0.8MPa, pass through POF 3 , under stirring for 5 hours, the reaction temperature is 100°C, the reaction pressure is 0.8MPa; POF 3 with P 2 o 5 The molar ratio to LiF is 1:1.2:1.7; then the temperature of the reactor is lowered to room temperature, and the insoluble matter is removed by filtration after pressure relief to obtain a light yellow transparent filtrate, the solvent is distilled off under reduced pressure, and the remaining solid is dried with fresh Acetonitrile was recrystallized at low temperature, the crystals were obtained by filtration, and LiPO was obtained after ...

Embodiment 2

[0032] In a closed stainless steel reaction kettle, LiOH and dry acetonitrile were added to the reaction kettle at room temperature, sealed and stirred, cooled to -45°C, and the atmosphere in the kettle was replaced with nitrogen, argon or helium with a water content of less than 1ppm three times. After the internal moisture content is less than 1ppm, the temperature is raised to 98°C, the pressure is raised to 0.75MPa, and the POF is passed 3 , reacted for 6 hours under stirring, the reaction temperature was 105°C, and the reaction pressure was 0.7MPa; POF 3 The molar ratio to LiOH is 1:1.3; then the temperature of the reaction kettle is lowered to room temperature, and the insoluble matter is removed by filtration after pressure relief to obtain a light yellow transparent filtrate, the solvent is distilled off under reduced pressure, and the remaining solid is washed with freshly dried acetonitrile Recrystallize at low temperature, filter to obtain crystals, and obtain LiPO ...

Embodiment 3

[0034] In a closed stainless steel reaction kettle, P 2 o 5 , LiF was added to dry acetonitrile and dimethyl carbonate mixed organic solvent with a mass ratio of 1:1, sealed and stirred, cooled to -35°C, and the atmosphere in the kettle was replaced with nitrogen, argon or helium with a water content of less than 1ppm three times , after the moisture content in the kettle is less than 1ppm, the temperature is raised to 102°C, the pressure is raised to 0.82MPa, and POF is introduced 3 , reacted for 7 hours under stirring, the reaction temperature was 95°C, and the reaction pressure was 0.9MPa; POF 3 with P 2 o 5 The molar ratio of LiF to LiF is 1:1.3:1~3; then the temperature of the reaction kettle is lowered to room temperature, and the insoluble matter is removed by filtration after pressure relief to obtain a light yellow transparent filtrate, the solvent is removed by distillation under reduced pressure, and the remaining solid is used for Freshly dried acetonitrile was...

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Abstract

The invention relates to a synthesis method of lithium difluorophosphate, belonging to the technical field of lithium battery electrolyte. The synthesis method is characterized by comprising the following steps: respectively adding P2O5, lithium-containing inorganic salt and dried organic solvent into a closed reaction kettle at normal temperature, airtightly stirring and cooling to -50DEG C to 30DEG C, displacing the atmosphere in the kettle three times with dried inert gas, increasing the temperature to 95DEG C-105DEG C after the content of moisture in the kettle is less than 1ppm, boosting pressure to 0.7MPa-0.85MPa; then introducing POF3, reacting for 5-15 hours under stirring, wherein the reaction temperature and pressure are respectively at 60DEG C to 180DEG C, and 0.5MPa to 2.5MPa, and the molar ratio of POF3 to P2O5 to lithium-containing inorganic salt is 1 to (0-1.5) to (1-5); and then filtering to obtain a filtrate, removing solvent, and recrystallizing solid to obtain crystal. The synthesis method has mild conditions, no side reactions appear, the technology process is simple, the product is easily separated and extracted, the moisture and free chlorine values are low, and the purity of the prepared product is high.

Description

technical field [0001] The invention discloses a method for synthesizing lithium difluorophosphate, which belongs to the technical field of lithium battery electrolyte. Background technique [0002] In recent years, due to the rapid development of smart devices such as mobile phones and tablet computers, the market share of small lithium batteries has grown rapidly. In addition, the technology of electric vehicles is becoming more and more perfect, and the market demand for large lithium batteries is also gradually released. It is expected that lithium batteries will maintain growth in the next few years trend. Lithium batteries are mostly secondary batteries, and their poor stability, poor low temperature resistance, and poor cycle characteristics are the main technical difficulties in their rapid development. Research has proved that lithium difluorophosphate as an electrolyte can effectively improve the above shortcomings of lithium batteries. [0003] In the prior art, ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/455H01M10/0568
CPCC01B25/455C01P2006/65C01P2006/80C01P2006/82H01M10/0568Y02E60/10
Inventor 牛会柱
Owner 山东永浩新材料科技有限公司
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