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A method for simultaneously preparing high-purity difluorophosphoric acid and high-purity lithium difluorophosphate

A technology of lithium difluorophosphate and difluorophosphoric acid, applied in chemical instruments and methods, phosphorus compounds, phosphorus halides/oxyhalides, etc., can solve the problems of difficult removal, many by-products, high energy consumption, etc., and avoid product hydrolysis , High conversion rate, energy saving effect

Active Publication Date: 2022-05-20
湖南法恩莱特新能源科技有限公司
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  • Claims
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AI Technical Summary

Problems solved by technology

[0003] In the prior art, the preparation methods of lithium difluorophosphate mainly include the following: (1) Lithium hexafluorophosphate is used as raw material to generate lithium difluorophosphate by hydrolysis, and the moisture content in the product of this method is difficult to control; (2) Lithium hexafluorophosphate, phosphorus Oxygen compound or oxyboron compound is used as raw material and calcined at high temperature. This method consumes high energy, the conversion rate of raw material is low, and inorganic impurities are difficult to remove; (3) using lithium hexafluorophosphate as raw material, in a non-aqueous solvent, with borate reaction, the acidity of the product in this method is difficult to control, and there are many by-products; (4) Lithium dichlorophosphate / dichlorophosphate is used as raw material to carry out fluorination and lithiation respectively. In the prior art, there are chloride ions, etc. High impurities, difficult to remove the problem
[0004] Lithium difluorophosphate is used as an additive in the electrolyte of lithium-ion batteries, and the impurities in it may seriously attenuate the performance of lithium-ion batteries.

Method used

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  • A method for simultaneously preparing high-purity difluorophosphoric acid and high-purity lithium difluorophosphate
  • A method for simultaneously preparing high-purity difluorophosphoric acid and high-purity lithium difluorophosphate

Examples

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Effect test

Embodiment 1

[0071] This example provides a method for simultaneously preparing high-purity difluorophosphoric acid and high-purity lithium difluorophosphate, which specifically includes the following steps:

[0072] (1) Nitrogen atmosphere, at 20°C, from the bottom at a rate of 450mL / min, into a 500mL three-necked flask filled with 135g of dichlorophosphoric acid, feed a 20% fluorine-nitrogen mixture with a mass fraction of fluorine gas, and after 322min, The system was purged with nitrogen; the temperature of the reaction system was raised to 110° C. for distillation, and 91.8 g of high-purity difluorophosphoric acid fractions were collected, with a yield of 90%.

[0073] (2) Under nitrogen atmosphere, drop 91.8g of high-purity difluorophosphoric acid into a solution prepared with 34.2g of lithium methoxide and 195g of methanol (water content ≤ 10ppm) at -5 to 15°C; heat the system to 25°C for 2 hours , and filtered to obtain the filtrate.

[0074] (3) Under the pressure of -0.1MPa, hea...

Embodiment 2

[0080] This example provides a method for simultaneously preparing high-purity difluorophosphoric acid and high-purity lithium difluorophosphate, which specifically includes the following steps:

[0081] (1) Nitrogen atmosphere, at 20°C, from the bottom at a rate of 500mL / min, into a 500mL three-necked flask filled with 150g of dichlorophosphoric acid, feed a 20% fluorine-nitrogen mixture with a mass fraction of fluorine gas, and after 331min, The system was purged with nitrogen; the temperature of the reaction system was raised to 110° C. for distillation, and 100.8 g of high-purity difluorophosphoric acid distillate was collected with a yield of 89%.

[0082] (2) In a nitrogen atmosphere, at -5 to 15°C, drop 100.8g of high-purity difluorophosphoric acid into a solution prepared by 37.6g of lithium methoxide and 212g of methanol (water content ≤ 10ppm); the system was heated to 30°C for 2 hours, Filtrate was obtained by filtration.

[0083] (3) Under the pressure of -0.1MPa,...

Embodiment 3

[0088] This example provides a method for simultaneously preparing high-purity difluorophosphoric acid and high-purity lithium difluorophosphate, which specifically includes the following steps:

[0089] (1) Nitrogen atmosphere, at 22°C, from the bottom at a rate of 600mL / min, into a 500mL three-necked flask filled with 200g of dichlorophosphoric acid, feed a 20% fluorine-nitrogen mixture with a mass fraction of fluorine gas, and after 350min, The system was purged with nitrogen; the reaction system was heated to 110°C for distillation, and 137.5 g of high-purity difluorophosphoric acid fractions were collected, with a yield of 91%;

[0090] (2) Nitrogen atmosphere, at -5 to 15°C, drop 137.5g of high-purity difluorophosphoric acid into a solution prepared by 89g of lithium isopropoxide and 291g of isopropanol (water content ≤ 10ppm); the system is heated to 30°C After reacting for 4h, the filtrate was obtained by filtration.

[0091] (3) Under the pressure of -0.1MPa, heat th...

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Abstract

The invention provides a method for preparing high-purity difluorophosphoric acid and high-purity lithium difluorophosphate at the same time, the method comprising the following steps: S1. After dichlorophosphoric acid is contacted and reacted with fluorine-nitrogen mixed gas, it is distilled, and fractions are collected to obtain high-purity difluorophosphoric acid. Purity difluorophosphoric acid; S2. Add the high-purity difluorophosphoric acid obtained in step S1 to the solution of organic lithium to react, and after filtering, obtain a filtrate containing lithium difluorophosphate; S3. After concentrating the filtrate obtained in step S2 under negative pressure, add non- The polar solvent is crystallized, filtered to obtain a filter cake, and the filter cake is dried to obtain the high-purity lithium difluorophosphate. The high-purity lithium difluorophosphate produced by this preparation method has a purity of ≥99.98%, free acid ≤100ppm, insolubles ≤100ppm, moisture ≤5ppm, SO 4 2‑ ≤5ppm, Cl ‑ ≤1ppm, the sum of metal ion impurity content≤1ppm.

Description

technical field [0001] The invention relates to the field of electrolyte additives for lithium ion batteries, in particular to a method for simultaneously preparing high-purity difluorophosphoric acid and high-purity lithium difluorophosphate. Background technique [0002] Lithium difluorophosphate is a lithium ion battery electrolyte additive. The role played by lithium difluorophosphate in the lithium-ion battery system is to participate in the formation of a uniform, dense, and highly stable SEI (Solid Electrolyte Interface) film on the surface of the positive and negative electrodes during the activation cycle (Formation Cycle), thereby reducing the The impedance of the battery delays the decomposition of the solvent and solute of the electrolyte, thereby prolonging the service life of the battery and improving the low temperature and rate performance of the lithium battery. Therefore, the preparation method of lithium difluorophosphate has become a research hotspot in ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B25/10C01B25/455
CPCC01B25/10C01B25/455C01P2006/80Y02E60/10
Inventor 邵俊华张利娟李海杰孔东波王郝为郭飞闫国锋宋东亮王亚洲侯红歧谢佳庆韩飞乔文忠
Owner 湖南法恩莱特新能源科技有限公司
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