The composite electrolyte with an insulation Sm2O3 and semiconductor NiO for advanced fuel cells

Novel Sm2O3−NiO composite was prepared as the functional electrolyte for the first time. The total electrical conductivity of Sm2O3−NiO is 0.38 S cm−1 in H2/air condition at 550 °C. High performance, e.g. 718 mW cm−2, was achieved using Sm2O3−NiO composite as an electrolyte of solid oxide fuel cells operated at 550 °C. The electrical properties and electrochemical performance are strongly depended on Sm2O3 and NiO constituent phase of the compositions. Notably, surprisingly high ionic conductivity and fuel cell performance are achieved using the composite system constituting with insulating Sm2O3 and intrinsic p-type conductive NiO with a low conductivity of 4 × 10−3 S cm−1. The interfacial ionic conduction between two phases is a dominating factor giving rise to significantly enhanced proton conduction. Fuel cell performance and further ionic conduction mechanisms are under investigation.