Anions for Lithium Battery Electrolytes: A Spectroscopic and Theoretical Study of the B(CN)[sub 4][sup −] Anion of the Ionic Liquid C[sub 2[sup mim]][B(CN)[sub 4]]

On the basis of computations, the B(CN)4 - (bison) anion is shown to be of interest as a fluorine-free alternative in lithium-conducting electrolytes. Compared to PF6 - the bison anion has an equally high stability toward oxidation, while at the same time offering a large reduction of the lithium-ion pair dissociation energy. The bison anion is readily available in a number of ambient-temperature ionic liquids (ILs). In this work, the Raman spectrum of the IL C2mim [B(CN)4] reveals an almost unperturbed bison anion and, consequently, the effects of the anion on the Raman shifts of C2mim + are also very small. © 2008 The Electrochemical Society.