A new anode for solid oxidefuel cells with enhanced OCV under methane operation

Abstract

A new SOFC anode material based upon oxygen excess perovskite related phases has been synthesised. The material shows better electrochemical performance than other alternative new anodes and comparable performance to the state-of-art of the electrodes, Ni–YSZ cermets, under pure hydrogen. Furthermore, this material shows an enhanced performance under methane operation with high open circuit voltages, i.e. 1.2–1.4 V at 950 °C, without using steam excess. The effect of the anode configuration was tested in one and four layer configurations. The optimised electrode polarisation resistances were just 0.12 Ω cm² and 0.36 Ω cm², at 950 °C, in humidified H₂ and humidified CH₄, respectively. Power densities of 0.5 W cm⁻² and 0.35 W cm⁻² were obtained in the same conditions. A very low anodic overpotential of 100 mV at 1 A cm⁻² was obtained under humidified H₂ at 950 °C. Samples were tested for two days in reducing and oxidising conditions, alternating heating and cooling processes from 850 °C to 950 °C, showing stable electrode performance and open circuit voltages. The results show that the substituted strontium titanates are very promising anode materials for SOFC.