Surface Modification of Ni-YSZ Anodes with a Cobalt NPs-Exsolving Perovskite Layer to Improve the Stability of Biogas-Fed SOFC

In this work, an A-site deficient perovskite, (La0.3Sr0.6Ce0.1)0.9Co0.1Ti0.9O3−δ (LSCCoT) was applied as an additional catalytic layer on Ni–YSZ anode for biogas-fuelled SOFC. Under reducing conditions, the formation of well-dispersed, socketed Co nanoparticles was observed due to the cobalt exsolution from the perovskite lattice. The structural and microstructural characterization confirmed phase stability of the perovskite after high-temperature reduction in hydrogen and the presence of exsolved nanoparticles on the grains’ surface. Electrical conductivity measurements showed thermally activated semiconducting behavior in air (Ea = 0.582 ± 0.121 eV) and a strongly enhanced conductivity with weak temperature dependence in hydrogen (Ea = 0.057 ± 0.001 eV). Single-cell tests performed under a CH4/CO2 (60/40 vol%) biogas mixture revealed a 30% increase in maximum power density at 800 °C compared to the reference cell. During 100 h of operation, the modified cell exhibited reduced performance degradation, improved internal reforming activity, and a more stable outlet gas composition.