The development of solid oxide co-electrolysis of H₂O and CO₂ on large-size cells and stacks

In the context of carbon neutrality, conversion of CO₂ into CO is an effective way for negative carbon emission. Electrochemical reduction is a novel developed pathway, among which, solid oxide co-electrolysis technology is promising for its high efficiency and low electricity demand. Researches concerning the large-size cell and stack of application level are important. This review, targeting at the not yet fully understood reaction mechanism and the most concerning issue of durability, details the reported factors playing important roles in the reaction mechanism and durability of co-electrolysis. It is found that the operating conditions such as inlet mixtures and applied current significantly affect the reaction mechanism of co-electrolysis and the experiments on button cells can not reflect the real reaction mechanism on industrial-size cells. Besides, the durability test of large-size single cells and stacks at high current with high conversion rate and the potential of solid oxide co-electrolysis combing with intermittent renewable energy are also reviewed and demonstrated. Finally, an outlook for future exploration is also offered.