Solid oxide fuel cells with proton-conducting La0.99Ca0.01NbO4 electrolyte

Several proton conductive ceramic oxides are evaluated for potential application in ceramic-NiO composite anodes for proton-conducting La0.99Ca0.01NbO4 (LNO) electrolyte-based fuel cells. Chemical compatibility tests show that most of the existing proton-conducting oxides are unfavorable for application in LNO electrolyte-based fuel cells because of undesirable reactions at high temperatures. Further considering the chemical compatibility with NiO and the ability to promote the densification of the deposited LNO electrolyte, LNO-NiO composite anode proves to be the only suitable anode candidate. With humidified hydrogen (∼3%H2O) as the fuel and static air as the oxidant, fuel cells based on LNO electrolyte film deposited on LNO-NiO anodes show a peak power density of 24 mW cm−2 at 750 °C, this value being one of the largest ever reported for LNO-based cells. Further investigation reveals that the polarization resistance of the cell is the major contribution to the total cell resistance, limiting the overall cell performance.