A variation on the chemical design through cation deficiency: In the case of Sr2Fe1.5Mo0.5O6-δ as the most promising electrode for symmetrical SOFCs and SOECs

Abstract

The prospective use of symmetrical electrochemical cells on solid electrolytes is extensive, encompassing fuel cells, electrolyzers, gas converters, gas separators, etc. However, the successful development of such cells faces a significant challenge: the search for electrode materials that exhibit high stability in oxidizing and reducing atmospheres, high electrode reaction rates, and resistance to redox cycling. In recent years, the complex oxide Sr₂Fe_1.5Mo_0.5O_6-δ has emerged as a promising candidate for use as an electrode material in symmetric cells. One approach to enhancing its performance is cation doping, although this strategy may not be optimal in certain cases due to the potential formation of impurity phases resulting from chemical interactions. An alternative and potentially more advantageous approach is to create a cation deficit. This study presents the initial findings of a comprehensive investigation into the electrochemical behavior of Sr_xFe_1.5Mo_0.5O_6-δ (where x = 2, 1.98, 1.95, 1.92, 1.9). The results demonstrate that strontium deficiency markedly influences the performance of the electrodes. The kinetics of oxygen reduction and hydrogen oxidation have been elucidated. The characteristics of electrochemical reactions in CH₄+CO₂ have been investigated. The outcomes of prolonged testing of electrodes have been presented. Many of the documented findings represent novel observations.