CESIUM-DEFICIENT CESIUM PHOSPHATES FOR PROTON CONDUCTING ELECTROLYTES

Proton conducting materials and membranes and electrochemical devices incorporating the materials and membranes are provided. Also provided are methods of making the materials and membranes and methods of operating the electrochemical devices. The proton conducting materials are solid acids that form superprotonic phases at elevated temperatures. The superprotonic phases have a cubic structure and the general formula: MH]HPO, where M represents one or more monovalent cations or a combination of monovalent cations and divalent cations, 0