Advances in high-temperature solid oxide electrolysis technology for clean hydrogen and chemical production: materials, cells, stacks, systems and economics

Solid oxide electrolysis cells (SOECs) are solid-state electrochemical devices that convert electrical energy into chemical energy in the form of H 2 , CO, and O 2 at 500–1000 °C. In recent years, interest in SOECs has soared because they offer extremely efficient and versatile means of producing green hydrogen and chemicals. However, SOEC technology requires further advancements for its successful commercialization. This review aims to comprehensively analyze the entirety of SOEC technology, identifying critical challenges and guiding future research. It covers both technical and economic aspects of all functional units in SOECs, including cells, stacks, and systems, with a particular emphasis on the unique characteristics of high-temperature materials. It clarifies the nano-, micro-, and macroscale phenomena, offering insights into their distinct electrochemical properties and degradation behavior. This paper encompasses both oxygen ion- and proton-conducting SOECs, with a particular focus on materials-related challenges in newly developed protonic ceramics. As for economic perspectives, the viability of further cost reduction and market penetration are discussed based on techno-economic assessments and various applications. Future research directions are outlined by defining key drivers and important areas for improvement for the wide adoption of SOEC technology and its contribution to a more sustainable, efficient energy landscape.