Methodology for Analysis of Solid Oxide Cells via Raman Spectroscopy

Solid oxide cells (SOCs) are highly efficient electrochemical energy conversion devices capable of operating in both fuel cell and electrolysis modes. The operating temperatures of SOCs (500 – 800 ^oC, for IT-SOCs) create opportunities for direct utilisation of a wide variety of reactants, including low-grade fuels such as biogas, however, in-situ characterisation of evolving electrode morphologies and compositions is challenging.  Conventional in-situ characterisation techniques, including impedance spectroscopy, can provide valuable information about electrochemical processes, but are unable to resolve specific chemical and physical changes during cell operation which can adversely affect SOC performance. Raman spectroscopy is a valuable analytical tool for in-operando monitoring of SOCs. Molecular species adsorbed on the surface can be identified, thus providing direct insight into reaction intermediates, material phase transformations and the presence of contaminants and poisons, such as carbon, chromium, sulfur and silica. Raman spectroscopy is a versatile technique that can be used for temperature sensing, semi-quantitative estimation of infiltrated material and many other applications. The design of optically accessible experimental setup will be presented alongside methodology for obtaining and interpreting in-situ Raman spectroscopic measurements. Raman spectroscopic evidence of carbon deposition during CO₂ electrolysis will be discussed.