Demonstration of high performance in a perovskite oxide supported solid oxide fuel cell based on La and Ca co-doped SrTiO3

Abstract

Perovskite electrodes have been considered as an alternative to Ni-YSZ cermet-based anodes as they afford better tolerance towards coking and impurities and due to redox stability can allow very high levels of fuel utilisation. Unfortunately performance levels have rarely been sufficient, especially for a second generation anode supported concept. A-site deficient lanthanum and calcium co-doped SrTiO₃, La_0.2Sr_0.25Ca_0.45TiO₃ (LSCT_A-) shows promising thermal, mechanical and electrical properties and has been investigated in this study as a potential anode support material for SOFCs. Flat multilayer ceramics cells were fabricated by aqueous tape casting and co-sintering, comprising a 450 μm thick porous LSCT_A- scaffold support, a dense YSZ electrolyte and a thin layer of La_0.8Sr_0.2CoO_3−δ (LSC)-La_0.8Sr_0.2FeO_3−δ (LSF)-YSZ cathode. Impregnation of a small content of Ni significantly enhanced fuel cell performance over naked LSCT_A-. Use of ceria as a co-catalyst was found to improve the microstructure and stability of impregnated Ni and this in combination with the catalytic enhancement from ceria significantly improved performance over Ni impregnation alone. With addition of CeO₂ and Ni to a titanate scaffold anode that had been pre-reduced at 1000 °C, a maximum powder density of 0.96 W cm⁻² can be achieved at 800 °C using humidified hydrogen as fuel. The encouraging results show that an oxide anode material, LSCT_A- can be used as anode support with YSZ electrolyte heralding a new option for SOFC development.