Synthesis and characterization of sb-doped SnO2 xerogel electrochemical capacitor

The performance of electrochemical capacitors made of Sb (6 mol %)-doped SnO2 xerogel electrodes and nonacidic aqueous electrolyte solutions, including 0.1-2 M KOH and Na2SO4, has been studied as a function of the thermal history of the xerogel. With increasing calcination temperature, the capacitance per unit weight was found first to increase, due to improved crystallinity, and then to decrease after 500 degreesC due to surface loss. The fully crystallized xerogel exhibited capacitance behaviors consistent with the space-charge model of a semiconductor, showing an average capacitance per unit real surface area of 8 and 16 muF/cm(2) within +/-1.0 V for calcination in air and in vacuum (0.1 Torr), respectively. Composite electrode using the xerogel as a substrate for highly dispersed RuO2 particles has been constructed, showing a capacitance of 670 F/g RuO2 with a base (1 M KOH) electrolyte solution. (C) 2001 The Electrochemical Society.