An innovative perovskite oxide enabling improved efficiency for low-temperature ceramic electrochemical cells

[Display omitted] •The SFT electrolyte powder synthesized using the co-precipitation technique.•The SFT shows 650 mW/cm2 and 1.14 A/cm2 at 520 °C in fuel cell and electrolysis mode.•Core-shell interface accelerates proton transport.•Band alignment, surface layer, and DRT analysis aid ion and protons transport. In recent years, energy carriers for renewable sources and devices that convert chemical energy into electrical energy, such as solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs), have made hydrogen production economically viable and have numerous industrial uses. We have designed SrFe0.3TiO3 (SFT) materials to function as SOFC and H-SOEC electrolytes at low operational temperatures of 520–420 °C. The SFT (600 °C) shows a higher fuel cell power density of 650 mW/cm2 and a reasonable current density of 1.14 A/cm2 in fuel cell and electrolysis cell mode at 520 °C. The formation of the surface layer enables high ionic and Proton conduction due to a high number of oxygen vacancies, and the core–shell type interface enables easy and quick proton transportation restricted to the surface. Energy band alignment and distribution relaxation time (DRT) were also evaluated to study ion transport in SFT materials. These results open up advanced avenues for the design of high-performance, sophisticated proton-conducting electrolytes for ceramic electrochemical cells.