Theoretical insights into the factors affecting the electrochemical performance of solid oxide electrolysis cells for CO₂ reduction

To mitigate the most severe impacts of climate change, a fundamental transformation of our energy system from fossil fuels to low-carbon energy sources is imperative and essential for a sustainable future. Among the various conversion technologies, carbon dioxide (CO₂) electrolysis is a promising approach for converting CO₂ to energy-dense chemicals. However, the low-temperature CO₂ electrolysis process is hindered by several challenges, including low energy efficiencies, poor selectivities, low catalytic activity, and stability, ultimately impacting its commercial viability. This has driven the development of high-temperature CO₂ electrolysis in solid oxide electrolysis cells (SOECs), which offers enhanced carbon-oxygen bond activation, higher current densities, and improved energy efficiencies, making it a more viable alternative to low-temperature electrolysis. The present work provides a comprehensive investigation of the CO₂ electrolysis process using SOEC, including a closer examination of the thermodynamic favorability of the process. We have reported novel insights into the critical roles of cathode, anode and electrolyte materials, revealing the opportunities for their enhancement and optimization. Additionally, the pressing issue of electrode degradation and reactivation strategies, as well as the degradation phenomena in the SOEC stack is discussed. Economic analysis is also incorporated to outline the techno-economic feasibility of this technology. Finally, future perspectives are included to highlight the important future considerations and provide a roadmap for this rapidly growing technology. By integrating these key aspects, the present work offers a more complete understanding of CO₂ electrolysis in SOECs and identifies opportunities for future research and development.