In-Operando Raman Spectroscopy Study on Oxygen Chemical Potential Gradient in Ni-SDC Cermet Anode for SOFCs

摘要

The cermet of Ni-oxide ion conductor is widely used as an anode in SOFCs. However, the usage of nickel induces various degradation phenomena during discharge operation; e.g., agglomeration and/or oxidation of nickel catalyst, and carbon deposition. In most cases, these degradation phenomena are triggered by the variation in the oxygen chemical potential inside the anode. In this study, then, in-operando Raman spectroscopy was conducted for Ni-SDC (Ni-Ce_(0.8)Sm_(0.2)O_(2-δ) cermet anode at 700°C by applying SDC as a probe for the detection of oxygen chemical potential. This is because the band related to oxygen vacancy in the Raman spectrum of SDC changes depending on the partial pressure of oxygen in the ambient atmosphere. The variation in oxygen chemical potential at the top surface of anode was successfully quantified. The effective reaction zone of anode is also discussed comparing with the data estimated from impedance spectra.