High-Performance Electrodes for Medium-Temperature Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs) are expected to provide high energy conversion efficiencies because of enhanced electrode performance due to high-temperature operation and of the efficient recovery of waste heat by additional means such as a bottoming cycle (gas turbine and steam turbine). The principle of the SOFC is shown in Fig. 1. Oxygen is reduced at the porous cathode to oxide ions (O²⁻). The oxide ions migrate across the solid oxide electrolyte to react with fuel gas at the porous anode. The cells can use a variety of fuels, which can be reformed internally to reactive fuels such as hydrogen or carbon monoxide on the anode using the waste heat energy at the high operating temperature of SOFCs. The operating temperature of the current first-generation SOFCs is restricted to very high values of about 1000°C due to insufficient performance of the state-of-the-art electrolyte (yttria stabilized zirconia, YSZ) and electrodes (Ni-YSZ cermet anode and Sr-doped LaMnO₃ cathode) at lower temperatures.