Efficient ion conductivity enhancement mechanism induced by metal ion diffusion of SOFCs based on Fe-doped Gd2O3 electrolyte

Abstract

Considerable efforts have been made in the past several decades to search for electrolytes that can work at low temperatures for solid oxide fuel cells (SOFCs). The rare-earth oxide Gd2O3 is a thermodynamically stable semiconductor material, but it has not yet been thoroughly explored for use in SOFC devices. In this study, a series of Fe-doped Gd2O3 with varying compositions were successfully synthesized to function as electrolytes for SOFCs. The as-prepared material, 10% Fe-doped Gd2O3 (Fe0.1Gd1.9O3), exhibited an excellent peak power density of 1352 mW/cm2 at 550 ℃, while the ionic conductivity reached 0.25 S cm−1. Various spectroscopic measurements, such as X-ray photoelectron spectroscopy, ultraviolet-visible (UV–vis) spectroscopy, and density functional theory calculations, were employed to understand the enhanced ion transportation mechanism and the improved performance of Fe-doped Gd2O3. The results showed that the Fe-doped Gd2O3 and energy bandgap tuning of electrolytes can significantly improve fuel cell performance at low temperatures, which is of great significance for the future development of low-temperature ceramic fuel cells.