Recent works showthe promise for lithium tetrafluoroborate (LiBF4) asanelectrolyte salt for lithium-ion batteries. In this paper, LiBF4 is synthesized by anovel reaction between the asprepared anhydrous Li2SO3 and (C2H5)2O⋅BF3 in an aprotic solvent. The moisture sensitivity and water-removing method of LiBF4 materials which has been dried under vacuum for 2h at different temperature, is studied by Fourier transform infrared spectroscopy measurements. Results show that almost
all of the adsorbed water would be removed at above 65 °C. With the increase of drying temperature, crystal water will decrease slowly, and almost disappear completely at 170 °C. However, due to the thermal decomposition of LiBF4, LiF and BF2OH impurities are formed as the temperature reaches 165 °C. So, we determine that the proper drying temperature is 155 °C, though the trace water cannot be removed thoroughly. Besides, influences of trace water on the electrochemical performance of Li/MCMB half-cell with LiBF4 as electrolyte salt has been investigated. Results show that discharge plateaus at about 1.5 Vvs. Li/Li+ will be lengthened with the increase of water content.Subsequently, the so-called solid-electrolyte interphase (SEI) film will become thicker and more resistant, which leads to poor Li+ ion migration and bad cycling performance.