Effects of specific adsorption of copper (II) ion on charge transfer reaction at the thin film LiMn 2O 4 electrode/aqueous electrolyte interface

Abstract

This study investigated the effect of a specific adsorption ion, copper (II) ion, on the kinetics of the charge transfer reaction at a LiMn 2O 4 thin film electrode/aqueous solution (1 mol dm −3 LiNO 3) interface. The zeta potential of LiMn 2O 4 particles showed a negative value in 1 × 10 −2 mol dm −3 LiNO 3 aqueous solution, while it was measured as positive in the presence of 1 × 10 −2 mol dm −3 Cu(NO 3) 2 in the solution. The presence of copper (II) ions in the solution increased the charge transfer resistance, and CV measurement revealed that the lithium insertion/extraction reaction was retarded by the presence of small amount of copper (II) ions. The activation energy for the charge transfer reaction in the solution with Cu(NO 3) 2 was estimated to be 35 kJ mol −1, which was ca. 10 kJ mol −1 larger than that observed in the solution without Cu(NO 3) 2. These results suggest that the interaction between the lithium ion and electrode surface is a factor in the kinetics of charge transfer reaction.