Researchers at the Institute of Science Tokyo have discovered a groundbreaking rubidium (Rb)-containing oxide-ion conductor, Rb5BiMo4O16, which boasts high conductivity and stability. This novel material, identified through computational screening and experiments, demonstrates superior performance due to low activation energy, large free volume, and unique structural features. The material's stability under different conditions presents a promising direction for solid oxide fuel cells and clean energy applications beyond hydrogen, such as natural gas and biogas. While solid oxide fuel cells offer sustainability benefits, challenges like cost and operating temperature range persist. The research team led by Professor Yashima investigated Rb's potential in oxide-ion conductors, culminating in the publication of their findings in Chemistry of Materials. Rb5BiMo4O16's exceptional properties, including high oxide-ion conductivity and stability, show promise in revolutionizing oxide-ion conductor technology. Factors like the large Rb atoms and the arrangement of MoO4 tetrahedra contribute to its remarkable conductivity. The material's stability under various conditions and at high temperatures further highlight its potential for future energy technologies. The discovery of Rb-containing oxides with high conductivity and stability opens new avenues for oxide-ion conductors, potentially leading to advancements in solid oxide fuel cells and other energy applications.