Single Electrode Heat Effects: I . Peltier Entropies of Gas Electrodes in Carbonate Paste Electrolytes

Standard Peltier entropies for the reactions in molten carbonate paste electrolytes at 1000°K have been determined from thermogalvanic measurements. The results are −217 and −118 J/mole°K, respectively. No dependence on electrolyte composition is observed. The reversible part of the Peltier entropy for the oxygen electrode reaction is estimated from thermodynamic data and reasonable agreement with the experimental results is found. It is concluded that the main contribution to the Peltier entropy arises from the transition from gaseous to liquid state, whereas the transfer entropies of the ionic species are of minor importance.