New materials for supercapacitors

Ruthenates based on SrRuO3 perovskite exhibit pseudocapacitance behavior. Replacing up to 20 mol% Sr by La leads to an increase of the specific capacity. The stability window of ruthenates is strongly dependent on B-site cations. Fe or Co substitution reduces the stability of the electrolyte whereas 20 mol% doping by Mn on the B-site increases the capacity without reducing the potential window. A capacitance up to 270 F/g was obtained by optimizing composition and preparation route. Cobalt or aluminum mixed hydroxides/oxyhydroxides also seems to have the potential for high pseudocapacitance behavior and exhibit capacitance up to 360 F/g, but the potential window is very limited.