Commercial scale preparation, properties and the performance of LiAsF6, LiPF6, LiBF4 electrolytes in secondary lithium ion and lithium cells

The performance of lithium and lithium ion accumulators is still dependent upon lithium salts such as LiPF₆, LiBF₄, LiAsF₆, LiSO₃CF₃ and LiClO₄ and/or their mixtures. We have described the manufacturing methods for the first three lithium salts, and their quality and performance in high energy secondary accumulators. These salts can be produced by aqueous, non-aqueous and metathetical routes. Currently, LiPF₆ is made by nonaqueous route by dissolving LiF in anhydrous HF and reacting it with PF₅ generated in-situ from PCl₅ and anhydrous HF. Lithium hexafluoroarsenate is prepared by neutralization HAsF₆ -6H₂O with LiOH; lithium tetrafluoroborate from neutralization of 50% HBF₄ and LiOH as well as reaction of BF ₃ with LiH_nF_n+1 solution. A mathematical model has been very useful in deciding the proper parameters for the production of LiBF₄ from commercially available inexpensive and environmentally less hazardous material, 50% aqueous HBF₄. Our electrochemical results show that LiPF₆, LiBF₄ and LiAsF₆ salts when used as an electrolyte in small coin cells, 2325 and 2016, are stable up to the discharge voltage of 4.5 volts