Calcium doping in double perovskite SmBa1-xCaxCo2O5+δ to enhance the electrochemical activity of solid oxide cell reversible oxygen electrode

Despite the remarkable reduction of carbon emissions due to COVID-19 pandemic during 2020, a reckless energy demand has compromised the 2050 agenda. In this scenario, reversible Solid Oxide Cells (rSOCs) could play a key-role due to their high fuel flexibility and versatility but there is still room for electrode stability and performance improvement. Lately, double perovskite materials have been widely studied due to their extraordinary fast oxygen diffusion rates and high conductivity mainly related to their layered ordering structure. In this work, the authors present the synthesis route and the electrochemical characterization of the A-site layered double perovskite structure SmBa1−xCaxCo2O5+δ in which calcium co-doping demonstrates a remarkable effect in the oxygen electrode activity. The best calcium doping corresponding to SmBa0.8Ca0.2Co2O5+δ displays a Rp reduction from 0.082 for the undoped material to 0.019 Ω·cm2 at 700 °C. Moreover, under anodic and cathodic operating conditions the electrocatalytic activity was further increased to 0.007 and 0.006 Ω·cm2 at η = ± 0.3 V, respectively. This behaviour demonstrates the suitability of the material to work as reversible oxygen electrode. Finally, the electrode material was subjected to a switching current aging test for over 100 h to prove the electrode stability under operating conditions.