ELECTRODE DEVELOPMENT FOR REVERSIBLE SOLID OXIDE FUEL CELLS

摘要

The reversibility of the electrodes for a solid oxide fuel cell (SOFC) with an yttria-stabilized zirconia (YSZ) electrolyte was examined using electrochemical impedance spectroscopy and current interrupt methods. The fuel electrodes were nickel/zirconia cermet and lanthanum-doped strontium titanate/doped ceria composites. The air electrodes were lanthanum strontium ferrite (LSF) and lanthanum strontium copper ferrite (LSCuF). Under the experimental conditions studied all four electrodes were able to operate in both the fuel cell and electrolyzer modes. The titanate/ceria fuel electrode performed substantially better in the electrolyzer mode than state-of-art Ni-YSZ. Moreover, it showed slightly higher activity for water electrolysis as compared to hydrogen oxidation. Air electrodes were less active in the electrolyzer than fuel cell modes. LSF typically provided higher overpotential losses in both modes than copper-substituted LSF. Changes in the defect chemistry of electrode materials under cathodic and anodic polarization are discussed.