Electrolytes for solid oxide fuel cells

Solid oxide fuel cells are extremely flexible energy conversion systems able to operate within a broad temperature range (500–1000°C), with a variety of fuels (from hydrogen to liquid fuels), including concepts able to be scaled to deliver power from the milliwatt to the megawatt range. The solid electrolyte, as an ionic charge carrier, is one central component that determines the operational characteristics of the fuel cell system, namely the working temperature. Design of new electrolytes includes manipulation of ionic defects concentration and mobility. Here, particular attention is given to the impact on ionic transport of point defects in various types of structures, dislocations, grain boundaries, and heterostructure interfaces. Properties derived from structural and compositional characteristics, but also from microstructural features, including recent complex engineered thin films, are reviewed. Major families of materials are compared with respect to key performance parameters. Finally, the effects of composition, structure, microstructure, and strain on ionic transport are assessed as complementary tools for future developments in solid electrolyte materials. This article is categorized under: Fuel Cells and Hydrogen > Science and Materials Energy Research & Innovation > Science and Materials