Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs) utilize hydrogen, methane, and other gases at high temperatures (about 1273 K) and directly convert chemical energy into electrical energy. Hence, they are expected to contribute toward realizing clean and highly efficient power generation systems. SOFCs are composed of highly heat-resistant ceramics. Yttria Stabilized Zirconia (YSZ) is for the electrolyte, (La, Sr) MnO₃ for the cathode, and YSZ/Ni cermet for the anode. The interconnect is a dense (La, Ca) CrO₃ or an Ni-Cr alloy. These materials are exposed to a wide oxygen partial pressure range, such as hydrogen and ambient air.

It is important to know the behavior of electrons and ions in ceramic materials as a function of temperature and oxygen partial pressure. We conduct electrochemical measurements for these subjects. In addition, the stability and the reactivity of materials are estimated by thermodynamic calculations to realize excellent material designs.

A chemical potentia diagram drawn by a calculation based on the thermodynamic database, This type of diagram is effective for designing the most stable composition of (La, Ca) CrO₃ interconnect in SOFCs.