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.