Boosting LT-CFC Performance with Cobalt-Enhanced CaTiO3 Electrolytes

Abstract

Attaining high ionic conduction using semiconductor electrolytes at low temperatures has attracted great interest, which is exciting but challenging. In this work, cobalt (Co) doping into CaTiO₃ is proposed to be used as an electrolyte for low-temperature ceramic fuel cells. The cobalt incorporation into CaTiO₃ creates a distinct surface charge region, facilitating ion transport through charge redistribution and pathway while suppressing the electronic conduction. It disrupts the lattice, generates oxygen vacancies, and improves charge transport efficiency, as confirmed by X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR). Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM) investigations show fine morphology and the formation of a deficit layer due to surface doping. The Co-doped CTO exhibits a high ionic conductivity of 0.123 S cm^–1 and better fuel cell performance of 620 mW cm^–2 at 520 °C. The results highlight a promising approach for designing efficient electrolytes for low-temperature ceramic fuel cells.