Electrolyte Stability in Direct-Carbon Fuel Cells with Molten Sb Anodes

Direct carbon fuel cells (DCFC) using oxide ion conducting electrolytes and molten Sb anodes have much promise for the efficient conversion of carbonaceous solid fuels into electricity. However, etching of the electrolyte, and ultimately cell failure, has been observed during operation. In this study, we have investigated this etching phenomenon as a function of the electrolyte composition and cell operating conditions and demonstrated that it is not electrochemical in nature, but rather results from reaction between the electrolyte and Sb₂O₃ that is produced during cell operation. Sintered solid electrolyte coupons of uniform thickness were immersed in molten Sb₂O₃ to check thickness change after high temperature annealing.