Electrode materials and reaction mechanisms in solid oxide fuel cells: a brief review

Following previous surveys of the solid electrolyte ceramics and electrode reaction mechanisms in solid oxide fuel cells, this review is focused on the comparative analysis of electrochemical performance, thermal expansion, oxygen ionic and electronic transport, and durability-determining factors in the major groups of electrode materials. The properties of mixed-conducting oxide phases with perovskite-related and fluorite structures, ceramic-metal and oxide composites, and catalytically active additives are briefly discussed, with emphasis on the approaches and findings reported during the last 10-15 years. The performance of conventional and alternative electrode materials in the cells with ZrO2-, CeO2-, LaGaO3-, and La10Si6O27-based electrolytes is appraised in the context of potential optimization strategies. Particular attention is centered on the cathode and anode compositions providing maximum electrochemical activity and stability and on the critical aspects relevant for electrode microstructure engineering.