High-temperature transport properties of BaSn1-xScxO3-δ ceramic materials as promising electrolytes for protonic ceramic fuel cells

Protonic ceramic fuel cells (PCFCs) offer a convenient means for electrochemical conversion of chemical energy into electricity at intermediate temperatures with very high efficiency. Although BaCeO3- and BaZrO3-based complex oxides have been positioned as the most promising PCFC electrolytes, the design of new protonic conductors with improved properties is of paramount importance. Within the present work, we studied transport properties of scandium-doped barium stannate (Sc-doped BaSnO3). Our analysis included the fabrication of porous and dense BaSn1-xScxO3-delta ceramic materials (0 <= x <= 0.37), as well as a comprehensive analysis of their total, ionic, and electronic conductivities across all the experimental conditions realized under the PCFC operation: both air and hydrogen atmospheres with various water vapor partial pressures (p(H2O)), and a temperature range of 500-900 degrees C. This work reports on electrolyte domain boundaries of the undoped and doped BaSnO3 for the first time, revealing that pure BaSnO3 exhibits mixed ionic-electronic conduction behavior under both oxidizing and reducing conditions, while the Sc-doping results in the gradual improvement of ionic (including protonic) conductivity, extending the electrolyte domain boundaries towards reduced atmospheres. This latter property makes the heavily-doped BaSnO3 representatives attractive for PCFC applications.

Automated summary

This study investigates the transport properties of scandium-doped barium stannate and finds that the Sc doping can improve the ionic conductivity, making the material suitable for PCFC applications even under reducing conditions.