ELECTROCATALYSIS IN SOLID OXIDE FUEL-CELL ELECTRODE DOMAINS

A significant improvement in power output is achieved by percolation of catalyst elements into the YSZ electrolyte surface during fabrication of a solid oxide fuel cell (SOFC). The resulting surface is referred to hereafter as a domain. The catalysts allow the electrochemical reactions to take place in the domain. Together with current collecting electrodes on the domains, a novel SOFC structure is fabricated. On the cathode domain Mn and Ce and on the anode domain Ni, Ru, and Pd are able to catalyze the reactions. The current and power densities of such cells are significantly higher than those obtained in the conventional sandwich type SOFC. The dispersion of electrocatalysts in the domain helps to achieve lower electrode overpotentials, because of its nanometric size. A redox mechanism is invoked for the catalysts in the domain. By using a less efficient oxygen reduction electrocatalyst such as Pt over the domains, it is shown that the electrode reaction occurs more easily in the domain and the contribution from the electronically conducting layer is predominantly charge collection. A friable layer of lanthanum strontium manganite can function as a good contact cathode over the domain. Pure Ni paint when applied over anodic domains is an excellent contact electrode.