Sulphur poisoning of solid oxide electrolysis cell anodes

Sulphur poisoning for state-of-the-art La0.8Sr0.2MnO3-δ (LSM) anodes of solid oxide electrolysis cell (SOEC) was studied under anodic current of 200 mA/cm2 in 1 ppm SO2 air. After polarization in 1 ppm SO2-containing air at 800 °C for 40 h, electrode polarization resistance as well as ohmic resistance of LSM electrodes were measured 24.83 Ω cm2 and 6.09 Ω cm2, which were around 4 as well as 3 times than initial values of LSM electrodes. Sulphur deposition prefers to take place at the LSM/YSZ interface and inner layer for LSM electrodes, leading to the formation of SrSO4 compounds, which is confirmed by XRD and then leads to the microstructural change of the LSM electrodes. The anodic polarization promotes the SrO segregation, which is supported by the observation of the deposition of SrSO4 compounds, accelerating LSM electrodes delamination. The results indicate the obvious poisoning effect for sulphur species of electrochemical activity as well as stability of SOEC electrodes.