Stabilizing the LSCF Oxygen Electrode of Solid Oxide Electrolysis Cell via Adjustment in Stoichiometry: Doping in a-Site with Ca and B-Site with Larger Cations

Lanthanum strontium cobalt iron oxide (LSCF) is considered as a superior state-of-the-art oxygen electrode material for SOEC because of its high mixed ionic and electronic conductivity, superior oxygen evolution activity, compatible thermal expansion coefficient (TEC) to ceria compatible, lower reaction activation energy, and suitable sintering temperature (1000). However, LSCF suffers in performance during the long-term SOEC operation due to issues related to undesired reactivity and Sr migration. Such issues are detrimental to the electrochemical performance as they trigger the formation of multiple oxide phases, including insulating phases and electrode or barrier layer delamination. Therefore, stabilization of LSCF phase via adjustment in stoichiometry is one of the crucial strategies to develop highly stable electrodes. In this work, several LSCF-based compositions have been synthesized by doping with size matching cation in A-site (La/Ca/Sr ratio adjustment), and doping B-site with larger cations such as Nb 5+ , Zr 4+ , and Ga 3 , attempting to enhance the chemical stability of LSCF and stabilize the perovskite structure. Electrical and chemical properties of these electrodes were studied using multiple characterization techniques. Electrocatalytic activity of these electrodes was evaluated in symmetric cells and in Ni-YSZ electrode-supported button cells. Structural and performance trends will be discussed in details.