La2Ce2O7 based materials for next generation proton conducting solid oxide cells: Progress, opportunity and future prospects

Abstract

The development of efficient and environmentally-friendly technology is the only possible way to solve the existing energy and environmental crisis. Solid oxide cells (SOCs) technologies have huge potential in different technologies including energy conversion devices (fuel cells), hydrogen production (electrolysis), co-conversion, natural gas upgrading (conversion of C1 molecules), green synthesis of ammonia, hydrogen separation membrane, and sensors. In few years, great effort has been paid for the development of ionic conducting materials for SOCs. Since Iwahara's discovery of proton conducting oxides in the 1980s, there has been a significant advancement in materials research that has been responsible for the creation of high performance SOCs by modifying the material's properties, such as ionic conductivity, mixed ionic electronic conducting (MIEC) materials, and triple conducting oxides. Recently, La2Ce2O7 (LCO) based materials with ionic (protonic and oxide ion) conductivity have been proposed as a new class of electrolyte for intermediate temperature solid oxide fuel cells as they exhibit high chemical stability, sufficient high ionic conductivity and low temperature sinterability compared to state-of-the-art proton conducting electrolytes. In order to engineer the materials properties, the fundamental understanding of materials such as true crystal structures, crystal structure tolerance ratio, hydration behavior, mechanism of ionic (oxide ions and protons) conduction, catalytic behavior, temperature of operation, ease of processing etc. is needed. All the above information is carefully reviewed for LCO based electrolyte