Electrochemical Intercalation of Bis(Trifluoromethanesulfonyl) Imide Anion into Various Graphites for Dual-Ion Cells

Abstract

Dual-graphite cells have been proposed as electrochemical energy storage devices using graphite as both, the negative and positive electrode. In this setup, the electrolyte cations intercalate into the graphite anode and the electrolyte anions intercalate into the graphite cathode during charge. On discharge, cations and anions are released back into the electrolyte. In this contribution, the electrochemical intercalation of the bis(trifluoromethanesulfonyl) imide anion (TFSI - ) into various graphites as cathode from an ionic liquid-based electrolyte, namely N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (Pyr 14 TFSI), was studied. The focus of this investigation is on the influence of the graphite properties such as the particle size and surface characteristics, i. e. the ratio of the basal plane to “non-basal plane” surface area, on the electrochemical performance of TFSI - anion intercalation.