Performance of supercapacitors with RuO2 electrodes spray deposited with aqueous/organic solvent mixtures: effect of substrate temperature

Abstract

RuO2 electrodes were spray-deposited utilizing an aqueous/organic solvent mixture at varied substrate temperatures. X-ray diffraction data supported the rutile structure and tetragonal phase of RuO2. FESEM images showed a porous structure with small spherical grains covering the entire substrate surface. Optical studies have shown that RuO2 films have bandgaps between 1.90 and 2.13 eV. Electrical resistivity was found in the range of 0.57 × 104 Ω-cm to 1.23 × 104 Ω-cm. CV (scan rate 5 mVs−1) results confirmed the specific capacitances of 560, 637, 687, 602 and 527 Fg−1 at substrate temperatures of 250, 275, 290, 300 and 325°C, respectively, in 0.5 M H2SO4 electrolyte. RuO2 provided a high specific capacitance 741 Fg−1 (current density 0.5 Ag−1) from GCD profile besides good specific capacitance holding of 87.66% over 3000 continuous charge–discharge cycles. The results show that RuO2 films spray deposited with aqueous/organic solvent mixtures give the best results.