Self-discharge and potential recovery phenomena at thermally and electrochemically prepared RuO2 supercapacitor electrodes

Abstract Films of ruthenium oxide (RuO 2 ) exhibit large, almost constant capacitance, over a potential range of ~ 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 RuO 2 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 2 film structure having three regions between which redistribution of oxidation states in the oxide film takes place on self-discharge and recovery.

[1]  Jim P. Zheng,et al.  Hydrous Ruthenium Oxide as an Electrode Material for Electrochemical Capacitors , 1995 .

[2]  B. Conway,et al.  Electron Microscopy Study of Formation of Thick Oxide Films on Ir and Ru Electrodes , 1984 .

[3]  H. Angerstein-Kozlowska,et al.  Surface oxidation and H deposition at ruthenium electrodes: Resolution of component processes in potential-sweep experiments , 1975 .

[4]  Su-Moon Park,et al.  The Anodic Oxidation of Nickel in Alkaline Media Studied by Spectroelectrochemical Techniques , 1987 .

[5]  John Crank,et al.  The Mathematics Of Diffusion , 1956 .

[6]  Brian E. Conway,et al.  ELECTROCHEMISTRY OF THE NICKEL OXIDE ELECTRODE: PART III. ANODIC POLARIZATION AND SELF-DISCHARGE BEHAVIOR , 1962 .

[7]  S. Ardizzone,et al.  "Inner" and "outer" active surface of RuO2 electrodes , 1990 .

[8]  B. Conway.  Transition from “Supercapacitor” to “Battery” Behavior in Electrochemical Energy Storage , 1991 .

[9]  B. Conway,et al.  The state of electrodeposited hydrogen at ruthenium electrodes , 1977 .

[10]  M. Pourbaix.  Atlas of Electrochemical Equilibria in Aqueous Solutions , 1974 .

[11]  K. Rajeshwar,et al.  Influence of temperature on the voltammetric response of thermal ruthenium oxide electrodes , 1991 .

[12]  H. Morley,et al.  DETERMINATION OF PARAMETERS IN OVERPOTENTIAL STUDIES , 1956 .

[13]  J. Weidner,et al.  Proton Diffusion in Nickel Hydroxide Films Measurement of the Diffusion Coefficient as a Function of State of Charge , 1995 .

[14]  B. Conway,et al.  Electrochemical oxide film formation at noble metals as a surface-chemical process , 1995 .

[15]  E. O'Sullivan,et al.  Influence of hydrolysis on the redox behaviour of hydrous oxide films , 1981 .

[16]  S. Trasatti,et al.  Ruthenium dioxide: a new electrode material. I. Behaviour in acid solutions of inert electrolytes , 1974 .

[17]  C. Iwakura,et al.  Electrochemical behaviour of the ruthenium oxide electrode prepared by the thermal decomposition method , 1977 .

[18]  D. Michell,et al.  A study of ruthenium electrodes by cyclic voltammetry and X-ray emission spectroscopy , 1978 .

[19]  S. Ardizzone,et al.  The point of zero charge of ruthenium dioxide , 1981 .

[20]  B. Conway,et al.  Overpotential decay behavior—I. Complex electrode reactions involving adsorption , 1976 .

[21]  L. Burke,et al.  The importance of reactive surface groups with regard to the electrocatalytic behaviour of oxide (Especially RuO2) anodes , 1981 .

[22]  B. Conway,et al.  Reversibility and Growth Behavior of Surface Oxide Films at Ruthenium Electrodes , 1978 .

[23]  J. Rishpon,et al.  Resolution of Fast and Slow Charging Processes in Ruthenium Oxide Films: An AC Impedance and Optical Investigation , 1984 .

[24]  B. Conway,et al.  Overpotential decay behavior—II. Generalized treatment for reaction pathways involving discharge, recombination and electrochemical desorption of adsorbed intermediates , 1977 .

[25]  B. Steele,et al.  Proton diffusion in crystalline ruthenium dioxide , 1980 .

[26]  S. Pizzini,et al.  Preparation, structure and electrical properties of thick ruthenium dioxide films , 1972 .