Chemical expansion of solid oxide fuel cell materials: A brief overview

The importance of oxygen non-stoichiometry induced expansion, known as chemical expansion, for the mechanical properties of solid oxide fuel cells (SOFCs) is discussed. The methods used to measure chemical expansion and the defects responsible for its existence are introduced. Recent work demonstrating the origin of chemical expansion in fluorite structured oxides for SOFCs is presented. Models used to predict stress induced by chemical expansion in SOFCs, highlighting the necessity of considering electrochemo-mechanical coupling relationships, are discussed.