Analysis of Capacitance Characteristics of C^sub 60^, C^sub 70^, and La@C^sub 82

Fullerenes and their derivatives are promising materials for supercapacitor devices due to their unique nanostructure that combines the reversible redox charge storage with the high surface area. In this article, the reversible redox charge storage of C^sub 60^, C^sub 70^, and La@C^sub 82^ in liquid ammonia solution is reported. An electrochemical analysis of these species using cyclic voltammetry is presented in conjunction with the theoretical interpretation. The relative magnitudes of transfer coefficients, which represent a measure of the symmetry of the energy barrier for oxidation and reduction of the monoanionic species of these fullerenes, suggest that the availability of the surface area permitting delocalization of π electrons is a determining factor of their first reduction potential. The relationship between these transfer coefficients and fullerene geometry also support previous conclusions that the La atom is located within the fullerene cage of La@C^sub 82^. The electrochemical measurements analyzed were made using a modified three-compartment cell. Advantages associated with this modified cell for analysis of capacitance characteristics of C^sub 60^, C^sub 70^, and La@C^sub 82^ are discussed.[PUBLICATION ABSTRACT]