Abstract
Hydrous ruthenium oxide‐coated titanium electrodes 
with high pseudocapacitance were prepared by cyclic voltammetry from an aqueous chloride solution in the −200 to 1000 mV range. The growth rate of 
, represented by 
(peak current) of the cyclic voltammograms, was constant up to cycle 120, but it decreased slightly between 120 and 240 cycles. Voltammetric responses studied by cyclic voltammetry as well as the charging and discharging behavior examined by chronopotentiometry in 
demonstrated the suitability of 
for use in electrochemical capacitors. X‐ray diffraction spectra exhibited an amorphous structure of this hydrous oxide film. The oxide consisted of mixed oxyruthenium species with various oxidation states as demonstrated by X‐ray photoelectron spectroscopy, and the 
surface showed a porous morphology. © 1999 The Electrochemical Society. All rights reserved.