The electrode potentials of the Group I alkali metals in the ionic liquid N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide

The redox couples M/M+ of the Group I alkali metals Lithium, Sodium, Potassium, Rubidium and Caesium have been extensively investigated in a room temperature ionic liquid (IL) and compared for the first time. Cyclic voltammetric experiments in the IL N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([C4mpyrr][NTf2]) and subsequent simulation of the data has allowed the determination of the formal potential ( E f 0 vs. ferrocene/ferrocenium), standard electrochemical rate constant (k0) and transfer coefficient (α) for each couple in the group. The trend in E f 0 in [C4mpyrr][NTf2] is remarkably similar to the established trend in the common battery electrolyte, propylene carbonate.