Preparation of magnesium hexafluorophosphate_industrial additives

Background and overview^[1][2]

Magnesium hexafluorophosphate is used as an electrolyte material for magnesium ion batteries and is the main raw material for manufacturing ion batteries. Ion batteries are currently recognized as an ideal green energy source in the world. With their small size and large capacity, they have been widely used as the main power source for portable appliances such as laptops, mobile phones, electric bicycles, and power tools. In recent years, ion batteries have also been used as energy sources for new energy vehicles such as electric vehicles and hybrid vehicles, and their application prospects are very broad. As a divalent ion, magnesium ions can react to produce twice the charge of magnesium ions per mole of ions. In addition, the abundance of magnesium in the earth’s crust ranks eighth, and its natural reserves are much higher than magnesium. For this reason, magnesium-ion batteries are expected to become a new generation of high-performance, low-cost energy storage technology.

Magnesium hexafluorophosphate

Apply^[3]

Magnesium hexafluorophosphate electrolyte has many outstanding advantages, such as: good stability; good compatibility with conventional organic solvents; high solubility in conventional organic solvents; the electrolyte composed of it has good Conductivity and ion mobility; non-corrosive to current collectors; etc. Based on the above advantages, magnesium hexafluorophosphate and its electrolyte have been widely used in ion batteries. Accordingly, its alkaline earth metal electrolytes, especially magnesium hexafluorophosphate and its electrolyte, are crucial to the development of magnesium ion batteries.

Magnesium ion batteries are the most promising energy storage batteries today. Compared with traditional batteries, they have greater electrical capacity, higher average output voltage, better cycle performance and conductivity, and are the current mainstream power supply products. Widely used in electronics, information, computers, military, aerospace, power vehicles, electric vehicles and other fields.

Preparation^[2]

Formosa Plastics Group

Method 1:

In a magnetically stirred reactor with a pressure of 1MPa, add 52g magnesium fluoride and 122g anhydrous hydrogen fluoride under nitrogen protection, stir electromagnetically to form a hydrofluoric acid solution of magnesium fluoride, and then add 438g dichlorohexafluoride Phosphoric acid, stir to form a suspension, and the reactor temperature is 25°C. Then gradually increase the temperature of the reaction kettle to 60°C and react for 4 hours. After the reaction is completed, the system is naturally cooled to room temperature, then cooled to 0°C and maintained for 2 hours to ensure complete crystallization. Then the system is excluded from the reaction. Hydrogen chloride gas was filtered and dried to obtain the finished product of magnesium hexafluorophosphate, and the mother liquor was prepared for reuse; the final product of hexafluorophosphate was 258.8g, and the one-time output rate reached 84.8%.

Method 2:

Dissolved 20 kilograms of dried and dehydrated magnesium fluoride in kilograms of anhydrous hydrogen fluoride, then airtightly introduced 110 kilograms of phosphorus pentafluoride gas, and reacted it at a temperature of 0°C and a pressure of 0.1MPa. 25% strength magnesium hexafluorophosphate solution.

The prepared magnesium hexafluorophosphate solution is atomized in a polytetrafluoroethylene-lined airflow drying equipment, maintaining the pressure at 0.4MPa; while atomizing, first introduce gas at the bottom of the dryer with a temperature of 100 ℃ hot gas flow; the hot gas flow is nitrogen, argon and other inert gases, and the moisture content of the solvent gas is less than 0.001%. After air flow drying, 119 kilograms of magnesium hexafluorophosphate powder crystals with a free hydrogen fluoride content of 0.015%, a moisture content of 0.0008%, and an average particle size of 200 microns were obtained. The obtained powdery crystals of magnesium hexafluorophosphate are transferred to a hot gas flow of nitrogen and argon inert gases with a temperature of 150°C and a moisture content of less than 0.001% for drying; then they are moved to a vacuum equipment to continue drying. The vacuum drying temperature is 40 ℃, vacuum degree is -0.03MPa. 118 kilograms of magnesium hexafluorophosphate electrolyte with a free hydrogen fluoride content of 0.008% that meets the electrolyte requirements for magnesium ion batteries was obtained.

Method 3:

Weigh pyridine:hexafluorophosphoric acid at a molar ratio of 1:0.6, put the pyridine into a stirring and heated reaction kettle, heat to 45°C, replace the air in the kettle with nitrogen, and add the hexafluorophosphoric acid solution dropwise , after reacting for 3 hours, a pyridine hexafluorophosphate suspension was obtained; the suspension was filtered, the filtrate was returned to the reaction solution, the filter residue was washed with ethanol, and the washed ethanol solution was recycled; the obtained pyridine hexafluorophosphate solid was heated at a temperature of 120°C Dry in a blast drying oven for 4 hours; weigh 18g of dried pyridine hexafluorophosphoric acid into a stirred reaction kettle, add 45mL of absolute ethanol and 3mL of high-purity water, preheat to 35°C, weigh 2.96g of magnesium carbonate, add and mix, magnesium After 9 hours of exchange reaction, the pyridine magnesium hexafluorophosphate solution was obtained by hot filtration; the pyridine magnesium hexafluorophosphate solution was concentrated and crystallized to obtain pyridine magnesium hexafluorophosphate crystals; the pyridine magnesium hexafluorophosphate crystals were dried for 4 hours to remove residual ions in the crystals. Ethanol and water, the obtained magnesium pyridine hexafluorophosphate is stored in an inert environment; the magnesium pyridine hexafluorophosphate is quickly moved into the decomposition reactor, and the equipment is closed and evacuated after nitrogen replacement. After the pressure in the reactor stabilizes to 1 Pa, the temperature is controlled to 30°C for heating. After 6 hours of reaction, battery grade magnesium hexafluorophosphate is obtained with a purity of 99.97%.