Raman evidence of the formation of LT-LiCoO2 thin layers on NiO in molten carbonate at 650°C

Abstract The structural evolution of thin layers of Co 3 O 4 elaborated on nickel-based substrates in the Li 2 CO 3 –Na 2 CO 3 carbonate eutectic at 650 °C as a function of time immersion is reported. Raman microspectrometry has been applied in order to provide more information on the nature of the protective cobalt oxide layers. The typical Raman fingerprint of the LT-LiCoO 2 compound has been obtained, with four well defined bands at 449, 484, 590 and 605 cm −1 , while XRD data are unable to distinguish the layered phase (HT) from the spinel one (LT). The mechanical stability of such films does not exceed 10 h in direct contact with the molten carbonate bulk at 650 °C; nevertheless, these conditions are much more corrosive than in a molten carbonate fuel cell (MCFC).