Realizing Coinstantaneous Multiple Benefits Generation from Sm_0.075Nd_0.075Ce_0.85O_2−δ/Al₂O₃ Heterostructure Electrolyte by Interfacial Engineering

The electrolyte in a solid oxide fuel cell (SOFC) should have high ionic conductivity to guarantee high fuel cell performance. This requires tuning of the electrolyte structure, which is often limited by poor electrolyte performance when the operating temperature. Here, we report ceria-semiconductor (Sm_0.075Nd_0.075Ce_0.85O_2−δ, SNDC)/insulator (i-Al₂O₃) heterostructure composite electrolyte which enhances ionic conductivity and improves fuel cell performance by the interfacial engineering. A maximum power density of 1312.5 mW·cm^-2 and an ionic conductivity of 0.18 S·cm^-1 at 550 °C were achieved. A small amount of an ultrawide band gap i-Al₂O₃ (molar ratio of 92SNDC-8Al₂O₃) effectively improved the ionic transport of the electrolyte by creating a potential energy barrier at the heterointerface. In addition, the n-i suppresses electron conduction and improves the ionic conduction, contributing to the outstanding electrochemical performance observed. The results demonstrate that the interfacial engineering of the electrolyte could be a simple and effective method to facilitate the fast transport of the ions in low-temperature SOFCs.