Activation of bifunctional perovskite oxides through exsolution in symmetrical solid oxide cells: Recent advances, challenges, and outlook

Solid oxide cells (SOCs) are devices that combine operating flexibility and high energy efficiency due to favored thermodynamics, enhanced kinetics, and the ability to exploit waste heat from industrial processes. To enable flexibility, however, symmetrical SOC (SSOC) configurations are required to employ bifunctional, redox-stable, and mixed ionic-electronic-conducting (MIEC) electrodes. The electrocatalytic properties of MIEC electrodes can be boosted by introducing catalytically active and sintering-/coking-tolerant nanoparticles through the redox exsolution method. Here, we explore the synergy between exsolution and SSOCs by using a comprehensive summary of recent advances in this field as a framework. We discuss the exsolved particles and host perovskite combinations while assessing the effect of the exsolution-triggering agents. The present review offers critical insights and guidance for identifying opportunities in new chemistries, cell pretreatments, and designs that could support SSOC technology in overcoming challenges and ultimately achieving commercial viability.