A solid oxide fuel cell's performance is largely determined by the ionic-conducting electrolyte. A novel approach is presented for using the semiconductor perovskite La0.25Sr0.75TiO3 (LST) as the electrolyte by creating surface superionic conduction, and the authors show that the LST electrolyte can deliver superior power density, 908.2 mW cm-2 at just 550 °C. The prepared LST materials formed a heterostructure, including an insulating core and a superionic conducting surface layer. The rapid ion transport along the surfaces or grain boundaries was identified as the primary means of oxygen ion conduction. The fuel cell-induced phase transition was observed from the insulating LST to a super O2- conductivity of 0.221 S cm-1 at 550 °C, leading to excellent current and power outputs.
Keywords: La-substituted SrTiO3; core−shell heterostructure; oxygen vacancies; solid oxide fuel cell; superionic conduction.