Ionic liquids for safe high performance lithium ion batteries

I&EC 116

Matthias Pascaly, matthias.pascaly@degussa.com1, Anna Prodi-Schwab, anna.prodi-schwab@degussa.com1, Michael Holzapfel, michael.holzapfel@psi.ch2, and Petr Novak, petr.novak@psi.ch2. (1) Creavis Technologies & Innovation, Degussa AG, Paul-Baumann-Str. 1, Science To Business Center, Marl, 45764, Germany, (2) Paul Scherrer Institut, Villigen, 5232, Switzerland
Lithium ion batteries show the highest energy density among usable electrochemical energy storage systems and have, thus, conquered consumer electronics markets like notebooks or cell phones. Nevertheless, the application range of lithium ion batteries is restricted because of a safety risk due to potential overcharging hazards. Technological improvements are needed to overcome both the potential hazard of the standard organic carbonate electrolytes as well as the rather poor performance at high charging rates and temperature extremes. At Creavis Technologies & Innovation, an ongoing research project focuses on the use of Ionic Liquids as non-flammable electrolyte materials. For the first time, an ionic liquid, 1-ethyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imide (EMI-TFSI), was shown to reversibly permit lithium intercalation into standard graphite when vinylene carbonate is used in small amounts as an additive. Further experimental evidence for the potential applicability of ionic liquids in this technology and safety tests will be presented.