Microstructure dependence of performance degradation for intermediate temperature solid oxide fuel cells based on the metallic catalyst infiltrated La- and Ca-doped SrTiO3 anode support

Abstract

Anode-supported solid oxide fuel cells with the configuration of the La_0.2Sr_0.25Ca_0.45TiO₃ (LSCT_A−) anode, YSZ electrolyte and La_0.8Sr_0.2Co_0.2Fe_0.8O₃ (LSCF)–YSZ cathode were fabricated using tape casting and co-sintering techniques followed by pre-reduction and impregnation. In order to improve the performance, the active anodes were prepared via the wet impregnation of metallic catalysts (Ni or Ni–Fe solution). The impregnation of 3 wt% nickel significantly improved the fuel cell performance from 43 mW cm⁻² for the bare LSCT_A− anode to 112 mW cm⁻² for the Ni–LSCT_A− anode at 700 °C in humidified hydrogen containing 3 vol% H₂O. More interestingly, the substitution of 25 wt% Fe to Ni further enhances the power density by a factor of 1.5, compared to the Ni-impregnated cell. The cell infiltrated with Ni–Fe solid solution shows a slower degradation than the other two cells after the first 20 h period. High-resolution back-scattered electron (BSE) and transmission electron microscopy (TEM) images performed on the cross section of the impregnated anodes with time after ion beam preparation show that the sintering of the catalyst particles on the scaffold surface and the interaction between backbone and catalyst are the predominant contributions for the degradation of cell performance.