High-performance Ti-doped strontium cobaltite perovskites as oxygen electrodes in solid oxide cells

Oxygen electrodes play a vital role in realizing high-performance solid oxide cells (SOCs) with high roundtrip efficiency, large-scale capacity, and long-term stability energy storage. This paper constructs Ti-doped strontium cobaltite perovskites (SrCo_1-xTi_xO_3-δ, SCTx, x = 0.2, 0.3, 0.4, 0.5) as newly stable oxygen electrodes for SOCs. The changes of oxygen vacancy in SCTx with Ti-doped concentration are investigated by X-ray photoelectron spectroscopy (XPS). The results show that the content of oxygen vacancy decreases with the enrichment of Ti doping. The area-specific resistance (ASR) of the symmetrical cell with SrCo_0.8Ti_0.2O_3-δ (SCT2) electrode is only 0.013 Ω cm² at 850 °C in air. The single cell with SCT2 oxygen electrode achieves the peak power density of 1.313 W cm⁻² at 850 °C under humidified H₂ conditions in fuel cells mode, and the current density reaches 2.95 A cm⁻² under an electrolytic voltage of 1.9 V at 850 °C for CO₂ electrolysis. The Density functional theory (DFT) calculations confirm that the oxygen vacancy formation energy is the lowest when the ratio of Ti to Co is 2:8, verifying the superior property of SCT2. This study comes up with a creation for developing high-stability and high-activity oxygen electrode materials that can be used for energy storage systems.