A fluorine-substituted pyrrolidinium-based ionic liquid for high-voltage Li-ion batteries

A fluorine-substituted ionic liquid based on a pyrrolidinium cation and a bis(fluorosulfonyl)imide anion was synthesized using a facile one-step reaction. The resulting ionic liquid is highly pure and when dissolved with LiFSI, the IL-based electrolyte showed good compatibility both in Li and graphite anodes, and superior voltage stability is demonstrated in a LiNi 0.5 Mn 0.3 Co 0.2 O 2 cell. Fluorinated pyrrolidinium bis(fluorosulfonyl)imides were successfully synthesized using a facile one-step reaction by reacting fluorinated pyrrolidine with CH 3 FSI with high purity and yield. The new IL shows good performance in Li-ion batteries.