Enhancing the performance of the BaTiO₃ electrolyte via A-site-deficiency engineering for low-temperature ceramic fuel cells (LT-CFCs)

The development of low-temperature solid oxide fuel cells (LT-SOFCs) is gaining abundant interest in semiconductor ionic materials (electrodes and electrolytes). Following this concept, an A-site deficiency technique is employed to unilaterally change BaTiO₃ to regulate ionic conduction, further improving the electrolyte's performance. The electrolytes, namely BaTiO₃, Ba_0·95TiO₃, and Ba_0·90TiO₃, have carefully been constructed and studied utilizing solid-state ball milling. The A-site deficiency in BaTiO₃ resulted to improve the ionic conductivity and minimize activation energy. This can be attributed to the higher number of oxygen vacancies on the surface and at the interfaces. The enhanced morphology, direct visualization of lattice structures, and the existence of oxygen vacancies caused by A-site deficiency have been studied in detail. Out of all the prepared electrolytes, Ba_0·90TiO₃ shows an enhanced fuel cell performance of 625 mW/cm². In comparison, the Ba_0·95TiO₃ achieved a reasonable fuel cell performance of 573 mW/cm², and BaTiO₃ achieved 548.40 mW/cm² at a low temperature of 550 °C. Compensating for the lack of A-site ions is a successful approach to improve ion transportation in fuel cells without creating any leakage of electric current. This is achieved by modifying the arrangement of energy bands that control the movement of charge carriers. The results of this work demonstrate that A-site-deficiency engineering can be used to improve the electrolyte performance of LT-SOFCs, making it a promising method for advancing fuel cell technologies in the future.