How to Achieve Maximum Utilization of Hydrous Ruthenium Oxide for Supercapacitors

The utilization of hydrous ruthenium oxide (denoted as was promoted by annealing the oxide in air as well as by mixing it with conductive activated carbon (AC) due to the significant improvement in intra- and interparticle electronic conductivity, respectively. The maximum specific capacitance of 1340 F/g (measured at 25 mV/s), very close to the theoretic value, was obtained from a composite consisting of AC and coated on graphite (denoted as with 10 wt % of sol-gel-derived nanodots annealed in air at 200°C for 2 h. The UV absorption spectral features showed a shift in to the red as the mean particle size of nanodots was increased, attributable to the surface plasmon resonance phenomenon. The average particle size of highly uniform nanodots, ranged from 2.05 to 3.01 nm, was estimated from the high-resolution transmission electron microscopy. The dependence of capacitive performance on the size and content of nanodots, evidenced by cyclic voltammetry and electrical impedance spectroscopy results, revealed the important influences of interparticle electronic conductivities on the utilization of The nanodots with and without annealing in air at 200°C for 2 h showed the amorphous structure from both the X-ray diffraction and electron diffraction analysis. © 2004 The Electrochemical Society. All rights reserved.