Electrochemical performance of symmetric solid oxide cells employing a Sc-doped SrFeO3-δ-based electrode

Symmetrical solid oxide cells (SSOCs) integrate the capabilities of solid oxide fuel cells and solid oxide electrolysis cells within a symmetric device, which have the advantage of simple fabrication and lower cost compared to conventional devices. Herein, to develop more advanced electrode materials to meet the catalytic activity for different electrode reactions, this study explores Sc-doped Sr0.9Fe0.8Sc0.1Co0.1O3−δ (SFSC) as an SSOC electrode material. Experiments show that Sc doping enhances the crystal stability of Sr0.9Fe0.9Co0.1O3−δ (SFC) in H2 and provides more oxygen vacancies for CO2 adsorption. Electrochemical tests reveal that the SFSC-Gd0.1Ce0.9O1.95 (GDC) electrode offers high power output, high CO2 electrolysis rates, and stability. Specifically, when operated as a fuel cell, the thus fabricated SSOC exhibits a peak power density of 781 mW·cm−2 and a polarization resistance of 0.117 Ω·cm2 at 850 °C, with operational stability over 300 h. Additionally, it reaches a peak current density of 1.96 A·cm−2 at 850 °C for CO2 electrolysis and is stable for 200 h at 0.45 A·cm−2 and 800 °C. Ab initio simulations further reveal a higher probability for oxygen vacancies in SFSC and an improved catalytic dissociation ability relative to Sr0.9Fe0.9Co0.1O3−δ for hydrogen and CO2. The stable and multi-functional SFSC-GDC electrode thus represents a compelling choice for SSOCs, advancing the prospects for efficient and cost-effective energy solutions.