Review of proton- and oxide-ion-conducting perovskite materials for SOFC applications

In this review, the essential use of perovskites and their structural properties associated with proton and oxide-ion conductivity are explained specifically for applications in solid oxide fuel cells (SOFCs), electrolyser cells and so on. The number of oxygen vacancies and their distribution in the crystal structure play a crucial role in perovskites, which exhibit good protonic and oxide-ion conductivity. Atmospheric stability at the operating temperature is another important factor that decides the long-term usage of the materials. Here the properties are summarised in terms of stability, proton defects, ordering and cation substitution. A basic understanding of all of these properties will give a direction to synthesis of compounds with desired proton and oxide-ion conductivity for applications in renewable and sustainable energy devices. A certain group of perovskite oxides, when prepared as nanostructures, is specifically used in fuel cell electrodes for improved performance. A few trends and highlights of current scientific advances in nanoperovskites for energy applications are discussed. The high stability of the proton conductor Ba3Ca1⋅18Nb1⋅82O8⋅73and substitution of new dopants in this compound for SOFC devices are highlighted in this review.