Advanced Fuel Cell Based on Perovskite La-SrTiO₃ Semiconductor as the Electrolyte with Superoxide-Ion Conduction

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 La_0.25Sr_0.75TiO₃ (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 O^2- conductivity of 0.221 S cm^-1 at 550 °C, leading to excellent current and power outputs.