Electrochimica Acta, Vol.42, No.23-24, 3541-3552, 1997
Self-Discharge and Potential Recovery Phenomena at Thermally and Electrochemically Prepared RuO2 Supercapacitor Electrodes
Films of ruthenium oxide (RuO2) exhibit large, almost constant capacitance, over a potential range of similar to 1.4 V in aqueous acid solutions. This behaviour has led to their development as supercapacitor materials giving many Farads per gram. Applications of electrochemical capacitors require minimum self-discharge rates. In the present paper, the self-discharge kinetics of charged RuO2 electrodes are studied and a remarkable phenomenon of successive potential recovery after sequential discharge transients is reported. The self-discharge and potential-recovery behaviour is analysed in terms of a process of diffusion of oxidation state involving proton and electron hopping, treated in a model of the RuO? film structure having three regions between which redistribution of oxidation states in the oxide film takes place on self-discharge and recovery.
Keywords:OVERPOTENTIAL DECAY BEHAVIOR;RUTHENIUM OXIDE;SURFACE;FILMS;DIOXIDE;TEMPERATURE;RESOLUTION;OXIDATION;CHARGE