Li⁺ insertion/extraction reaction into/from carbon electrode in room temperature ionic liquid using asymmetric quaternary ammonium cation

For the application of room temperature ionic liquid as an electrolyte base for lithium batteries, carbonaceous electrode was cycled in the electrolyte with N-methyl-N-propylpiperidinium bis(trifluoro methanesulfonyl)imide which is promising ionic liquid with higher cathodic stability. Solid electrolyte interface favorable for Li⁺ insertion could not be formed on the graphitized carbon electrode and capacity observed was c.a. 10-20 % of the theoretical value. On the other hand, hard carbons could be cycled with a consistent capacity in the ionic liquid based electrolyte, showing the possibility of the ionic liquid for the electrolyte of lithium-ion type batteries.