Reaction of Water with Hexafluorophosphates and with Li Bis(perfluoroethylsulfonyl)imide Salt

There have been concerns and speculation about the reactivity of electrolytes with water in lithium‐ion cells and also concern about gas pressure buildup which can occur. This report identifies the chemical nature of the gas evolved and derives some of the reaction kinetics. Comparison is made with hexafluorophosphates of sodium and potassium which do not react with water. The lithium salt of bis(perfluoroethylsulfonyl)imide (BETI) is also unreactive to water. These results may help researchers to understand results from the use of or to choose a nonreactive lithium salt such as BETI. © 1999 The Electrochemical Society