GAS ELECTRODE-REACTIONS IN MOLTEN CARBONATE MEDIA .2. OXYGEN REDUCTION KINETICS ON CONDUCTIVE OXIDE ELECTRODES IN (LI + K)CO3 EUTECTIC AT 650-DEGREES C

The electrode kinetics for oxygen reduction on conducting metal oxides, including lithiated NiO (formed in situ) and Sb-doped SnO//2, have been investigated. Kinetic measurements were carried out by using ac impedance and coulostatic relaxation methods. The ac behavior on the oxide electrodes was analyzed on the basis of a modified Randles-Ershler type equivalent circuit which takes into account the effect of non-faradaic components due to the semiconducting oxide films. The kinetic parameters ( the double layer capacity, film capacity and film resistance) were obtained by a least squares curve fitting method under P(O//2)/P(CO//2) equals 0. 9/0. 1 atmosphere. The exchange current density was found to be 10 to 20 mA cm** minus **2 at the oxide electrodes, assuming n equals 2. The coulostatic relaxation experiments supported the magnitude of the i//0 values.