New high‐temperature proton conductors for fuel cells and gas separation membranes

Abstract

Abstract High‐temperature proton conductors and mixed proton–electron conductors have the potential to serve as membranes in processes within future environment‐friendly energy technologies. Proton‐conducting solid oxide fuel cells (PC‐SOFCs) offer, among other advantages, better and simpler fuel utilization than conventional SOFCs. Mixed proton–electron conductors may be applied as membranes for hydrogen production and purification with the advantage of 100% selectivity, higher operation temperature, and improved long‐term stability compared to present membrane candidate materials. State‐of‐the‐art high‐temperature proton‐ and mixed proton–electron conductors consist of the basic alkaline‐earth cerates and zirconates. The reactivity of these materials with, in particular CO 2 , has so far limited implementation of high‐temperature proton conductors in industrial processes. Consequently, there is a need for new materials that combine the required functional properties with sufficient mechanical and chemical stability. The present contribution summarizes the literature on high‐temperature proton conductors with emphasis on newly developed materials. The functional characteristics of the materials are discussed in view of the current understanding of thermodynamics, transport parameters, and physical material properties.