Introduction

Lithium hexafluorophosphate(picture 1) is an inorganic substance with the chemical formula LiPF6, white crystal or powder[1]. Easily soluble in water, but also soluble in organic solvents such as low-concentration methanol, ethanol, acetone, carbonates, etc. It is the most important part of the electrolyte composition, accounting for about 43% of the total cost of the electrolyte. In the fluorine chemical industry, although the traditional products have a significant year-on-year decline, the demand for high-end products has maintained a strong momentum. In particular, the production and sales of lithium hexafluorophosphate continued to maintain a good trend. With the continuous expansion of the new energy field in the future, lithium hexafluorophosphate is expected to usher in a continuous explosion. In the future, other new lithium salts are expected to replace lithium hexafluorophosphate.

Picture 1 The physical drawing of lithium hexafluorophosphate

The properties of lithium hexafluorophosphate

Lithium hexafluorophosphate is a white crystal or powder with a relative density of 1.50 and strong deliquescence; easily soluble in water, but also soluble in low-concentration methanol, ethanol, acetone, carbonates and other organic solvents. Lithium hexafluorophosphate decomposes when exposed to air or heated. Lithium hexafluorophosphate decomposes rapidly due to the action of water vapor when exposed to air or heated, releasing PF5 and producing white smoke. Lithium hexafluorophosphate will not decompose if used and stored according to specifications. Avoid contact of lithium hexafluorophosphate with oxides. Lithium hexafluorophosphate is easily soluble in water, and is also soluble in low-concentration methanol, ethanol, propanol, carbonate and other organic solvents.

The synthesis of lithium hexafluorophosphate

The first is the wet method. In the method, lithium salt is dissolved in anhydrous hydrofluoric acid to form LiF·HF solution, and then PF5 gas is introduced for reaction to produce lithium hexafluorophosphate crystals. After separation and drying, the product is obtained; the second is dry method. The method is to treat LiF with anhydrous HF to form porous LiF, and then pass PF5 gas for reaction to obtain the product. The third is the solvent method. The method is to make lithium salt react with alkali metal salt, ammonium salt or organic amine salt of fluorophosphoric acid in an organic solvent to crystallize, thereby preparing lithium hexafluorophosphate product.

Application

Lithium hexafluorophosphate is used as a lithium-ion battery electrolyte, mainly used in lithium-ion power batteries, lithium-ion energy storage batteries and other daily batteries. It is also an irreplaceable lithium-ion battery electrolyte in the near and medium term. Lithium hexafluorophosphate is the most important component of the electrolyte composition, accounting for about 43% of the total electrolyte cost. In the fluorine chemical industry, although the traditional products have a significant year-on-year decline, the demand for high-end products has maintained a strong momentum. In particular, the production and sales of lithium hexafluorophosphate continued to maintain a good trend. With the continuous expansion of the new energy field in the future, lithium hexafluorophosphate is expected to usher in a continuous explosion.

Industrial Development

Lithium hexafluorophosphate is the key electrolyte in the electrolyte. Before 2004, Japan's Rising Chemical, Morita Chemical and Kanto Denka monopolized the lithium hexafluorophosphate industry. Around 2012-2014, Chinese companies began to break through the preparation technology and process of lithium hexafluorophosphate, although foreign companies are also New processes and formulas have been introduced, but the gap between domestic and foreign products is not large. From 2015 to 2017, Chinese companies still aggressively expanded production, which brought periodic surpluses and caused huge price fluctuations. However, in the medium and long term, on the one hand, domestic and foreign demand is still growing vigorously, and the decision-making process for Japanese companies to expand production is lengthy and conservative. . Coupled with the huge cost advantage of Chinese enterprises after upgrading their technology and scale, the new solute demand at home and abroad may be dominated by Chinese enterprises.

Reference

1 Edited by Wang Guoqing Inorganic chemistry Beijing: China Medical Science and Technology Press, 2008.08