Trends in electrode development for next generation solid oxide fuel cells

High temperature electrochemical devices, such as solid oxide fuel cells (SOFCs), will play a vital role in the future green and sustainable energy industries due to direct utilization of carbon-based fuels and their ability to couple with renewable energies to convert by-products into valuable fuels using solid oxide electrolysis cells (SOECs). All-solid-state design provides a great opportunity toward the optimization of durability, cost, efficiency and robustness. Electrodes, one of the most important components that facilitate the electrochemical redox reactions, have been actively investigated for several decades to optimize a matrix of chemical composition, microstructure, and performance. Although some mixed ionic electronic conductors (MIECs) can provide electrochemically active surface with excellent chemical tolerance comparing to the composite electrodes made of conventional ceramic electrolyte and metal (cermet), their electrochemical activities may not be high enough to obtain a desirable power, even at moderate temperature operation. This shortage could be improved by engineering the microstructure of the electrodes, which control electrochemically active sites in SOFCs and SOECs. In this article, the current trends in electrode-engineering techniques for advanced SOFCs are reviewed.