Strontium ruthenate perovskite as the active material for supercapacitors

Strontium ruthenate SrRuO3 is a well functioning member of the family of me tallic conducting oxides with the perovskite type structure. Its properties relevant to electrochemical capacitors depend on the conditions of synthes is as well as on the nature and amount of dopants. Undoped SrRuO3 prepared by a coprecipitation process exhibits capacitances of about 10 F g(-1). Rep lacing the B cation Sr by Fe or Co does not influence the capacitance but d ecreases the stability window of the KOH electrolyte. Mn doping however as well as La doping on the A-site increases the capacitance to values of 20-3 0 F g(-1). A model of the charge storage mechanism is given and discussed. It involves protonic conduction via the Grotthus mechanism inside the perov skite structure. A new synthesis technique based on pyrolysis of a salt sol ution is introduced which yields ten times larger specific capacitances. (C ) 1999 Elsevier Science S.A. All rights reserved.