LiPF 3 (CF 2 CF 3 ) 3 from Merck KGaA ͑LiFAP͒ was tested as a new electrolyte for Li-ion batteries that can replace the commonly used LiPF 6 . The latter salt is known to be unstable, to decompose thermally to LiF and PF 5 , and to readily undergo hydrolysis with protic species to form HF contamination in solutions. The latter contamination may have a detrimental impact on the performance of both anodes and cathodes for Li-ion batteries. Solutions comprising LiFAP, LiPF 6 , and LiN(SO 2 CF 2 CF

more »

... 3 ) 2 ͑LiBETI͒ in mixtures of ethylene, dimethyl, and diethyl carbonates were tested with composite graphite and LiMn 2 O 4 electrodes. The tools for this study included voltammetry ͑fast and slow scan rates͒, chronopotentiometry, impedance spectroscopy, Fourier transform infrared, and X-ray and photoelectron spectroscopies. It was found that LiFAP is superior to LiPF 6 as an electrolyte for both graphite anodes and LiMn 2 O 4 cathodes. This should be attributed to the different surface chemistry developed on these electrodes when LiPF 6 is replaced by LiFAP. An important impact of such a replacement is probably the absence of possible pronounced HF contamination in LiFAP solutions.