Mixed conducting components of solid oxide fuel cell anodes

Developments of intermediate-temperature solid oxide fuel cells (IT SOFCs) require novel anode materials with high electrochemical activity at 800–1070 K. In order to assess the role of oxide components of Ni- and Cu-containing cermets, a series of electrodes containing 8% yttria-stabilized zirconia (Y8SZ), Ce0.8Gd0.2O2−δ (CGO) and TbZrO4−δ with fluorite-related structure, zircon-type Ce0.8Ca0.2VO4+δ, pyrochlore Gd1.86Ca0.14Ti2O7−δ (GCTO), and La0.9Sr0.1Al0.65Mg0.15Fe0.20O3−δ perovskite, were studied in contact with (La0.9Sr0.1)0.98Ga0.8Mg0.2O3−δ (LSGM) electrolyte. The best performance was found for anodes comprising a stable ion-conducting component, such as Y8SZ or GCTO, and one Ce-containing phase, such as CGO or cerium vanadate. Anode performance is less dependent on the ionic conductivity of oxide components than on redox stability or interaction between different cell materials. Surface modification with ceria substantially reduces overpotentials of all cermet anodes. For Ni–CGO and Cu–CGO, such activation of yields about 100–115 mV at 1073 K and 200 mA/cm2 in 10% H2–90% N2, for both anodes.