Carbon tolerance effects of Sr₂NiMoO_6-δ as an alternative anode in solid oxide fuel cell under methane fuel condition

Sr₂NiMoO_6-δ (SNMO) with a double perovskite structure has been investigated as an alternative anode material for solid oxide fuel cells. The SNMO anode was compatible with the GDC electrolyte at the SOFC operating conditions. The SNMO anode was not stable at high temperatures and reducing atmospheric conditions, where Ni exsoluted from the SNMO double perovskite structure to form Ni nanoparticles. Ni nanoparticles provided highly electrochemically active sites in both H₂ and CH₄. Ni nanoparticles also provided chemically active sites for the pyrolysis of methane under H₂O shortage, leading to carbon deposition on the anode. To improve the cell performance, the SNMO anode was modified by a GDC thin film coating on the anode pore wall surface to increase the number of reaction sites and also accelerate the electrochemical reaction kinetics of the anode. The anode polarization resistance in CH₄ was decreased by the GDC modification from 18.39 Ωcm² to 0.55 Ωcm² at 800 °C. The 60% of the cell performance was improved by the GDC modification on the SNMO anode. The GDC-modified SNMO anode cell was stable for 100 h when CH₄ fuel was used.