Grafting doped manganite into nickel anode enables efficient and durable energy conversions in biogas solid oxide fuel cells

Biogas, consisting of CH4, CO2 and a small amount of H2S, is one of the most promising alternative energy sources. Solid oxide fuel cells (SOFCs) are ideal technologies to efficiently utilize biogas for producing electricity and heat. However, this is precluded because the conventional Ni-Y2O3 stabilized ZrO2 (Ni-YSZ) anode for SOFC is inclined to cause carbon formation as well as to form inert and non-conductive S-containing species in biogas. To directly utilize the biogas in SOFC, a hybrid anode material, combining the slightly compromised merits of the conventional Ni-YSZ cermet and the alternative anode, i.e., PrBaMn2O5+δ perovskite oxide, is developed in this study. The PrBaMn2O5+δ dramatically resists the carbon formation and S adsorption on Ni surface and at the same time, it serves as the CO2-captor, oxygen source and the medium for O2− diffusion to accelerate both the carbon removal and S desorption processes. At 800 °C, the peak power density of the cell with the hybrid anode attains 1.35 W cm−2 in biogas, and no significant degradation is observed during the stability test. The hybrid anode, therefore, displays excellent activity, superior coke/sulfur resistance and stability in biogas, offering a promising technology for biogas utilization.