Yttria-doped ceria anode for carbon-fueled solid oxide fuel cell

Direct carbon fuel cells offer twice the efficiency compared with conventional coal-fired power plants and the highest efficiency among various fuel cells. However, the delivery of solid fuel to electrode/electrolyte interface is a critical issue and hinders the long-term performance of the fuel cell. The use of mixed ionic electronic conducting anodes has the potential to reduce the problem by shifting the fuel oxidation reaction from anode/electrolyte to anode/solid carbon interface. In search for a better anode material, Y2O3-doped ceria has been investigated as a suitable anode material for use in direct carbon fuel cells and the performance compared with Gd2O3-doped ceria. These materials have high ionic conductivity in oxidizing environments and are also known to have reasonable mixed ionic and electronic conductivity in reducing environments. In this manuscript, the stability of the anode materials in fuel cell operating environments has been investigated with X-ray diffraction (XRD) and scanning electron microscopy. Electrochemical impedance spectroscopy, in pure N-2 and CO2/N-2 anode chamber atmospheres, has been used to deconvolute the contribution of various fuel cell components to voltage losses and to elucidate the reaction mechanism. No precious metals were used on the anode side, neither as a catalyst nor as a current collector.