Lithium-ion Battery Electrolyte Material Of Lithium Hexafluorophosphate Preparation And Properties

Lithium-ion secondary battery (LIBLi-Ion battery) is the third generation of the small and high energy density batteries after Ni-Cd and Ni(H) batteries. It is protective to environment and represents the most advanced level of battery techniques. One of the critical techniques is to study and develop new high energy density electrolyte materials. It is widely recongnized that lithium hexafluorophosphate is the best electrolyte material of lithium ion battery for its excellent performance now being used. The status about research of lithium hexafluorophosphate at home and abroad was presented based on summarizing Li-ion Batteries and some relative data. Although many studies and methods, such as traditional method, complex method, solution method, and et al. can be used to synthesize lithium hexafluorophosphate electrolyte material. And the properties of the material are improved to some extent, but many of these methods are still not suitable for mass production because of the complicated techniques or the high cost. So the emphasis of present studies is to develop a simple and easy controlled method which can be fit for industrialization and synthesis of LiPF₆ with excellent electrochemical characteristics.In order to solve the problem, the laboratory synthesis of LiPF₆ and relative electrochemical studies of LiPF₆ were made. The goal is to provide necessary pre-period data for industial production of LiPF₆ suitable for salt lakes. If this goal could be achived, certain impulse effects would be made to the development of LiPF₆ and Li-ion battery industry.The main research contents are as follows:1. Superiority of preparing lithium hexafluorophosphate by solvent method has been summarized up. Based on the previous studies, improved and simplified method of preparing of high purity lithium hexafluorophosphateis was developed. In this course, the abundant Salt lake primary product lithium carbonate was used as raw materials, low toxicity and causticity acetonitrile was used as solvent.2. Qualitative study of lithium hexafluorophosphateis were conducted using infrared spectrum and XRD pattern method. The analytical results coincided well with each other, and the results indicated that self-made lithium hexafluorophosphate is of ahigh purity.3. The thearmal decompostiton analysis of self-made lithium hexafluorophosphate indicated that the decompostion process of lithium hexafluorophosphate is very complex. It decomposed at least by two steps in common laboratory conditions. But the concrete mechanism of the decompostion still needs to be studied further.4. Self-made lithium hexafluorophosphate was made into lmol-L"1 electrolyte to examine its electrochemical property. The results indicated that it had high conductivity, fine electrochemistry performance of take in and take off of lithium and good circulation performance.To some extent, the study was beneficial for the development of simply synthesis technology of lithium hexafluorophosphate and understanding the basic theory concerned with the preparation of electrolytical materials.