Influence of Ionic Liquid Species in Non-Aqueous Electrolyte on Sodium Insertion into Hard Carbon

The electrochemical insertion and de-insertion of sodium ion in hard carbon has been monitored in electrolytes consisting of sodium perchlorate (NaClO4), propylene carbonate (PC), and an ionic liquid N,N-diethyl-N-methoxy-ethyl ammonium bis(trifluoromethane sulfonyl)imide (DEMETFSI). Voltammetric observation revealed that the reversible sodium insertion is inhibited by the content of DEMETFSI in the electrolyte. The reversible signs of sodium insertion become obvious when the volumetric content of DEMETFSI was 70%. The inhibition effect for sodium insertion by DEMETFSI is somewhat in relation to the change in coordination with sodium ion in electrolyte. (C) The Electrochemical Society of Japan, All rights reserved.