Preparation and Characterization of Phosphorus Pentafluoride Gas for Lithium Ion Battery Electrolyte Salt
LIU Jian-wen, LI Xin-hai, WANG Zhi-xing, GUO Hua-jun and HU Qi-yang School of Metallurgical Science and Engineering, Central South University, Changsha 410083, P. R. China
A novel preparation method of phosphorus pentafluoride(PF5) is introduced in details in the article. Phosphorus pentafluoride is mainly used to synthesize lithium ion battery electrolyte salt. In the experiment mesne-product—hexafluorophosphoric acid(HPF6) was firstly prepared from phosphorus pentoxide(P2O5) and anhydrous hydrogen fluoride(HF), according to the chemical stoichiometrics, the optimum amount of excess HF used was about 60% and the optimum reaction time was 4 h; then HPF6 was dehydrated by oleum with an excess amount of 35%―40% which was heated for 40―50 min at 150 °C; thus HPF6 was decomposed to a mixture of gases containing PF5; impurity gases were removed through condensation in the presence of cooling water at 0 °C, then PF5 of high purity was eventually prepared. The production was characterized by infrared(IR) spectrometry and gas chromatography-mass spectroscopy-selected ion monitoring(GC-MS-SIM). Eventual results indicate that PF5 prepared by the novel method has a high target purity and a low amount of impurity and water.