Structural stability and interfacial reaction mechanisms of CeO ₂ ‐coated metallic interconnectors under solid oxide fuel cell anode service conditions

Abstract Special service environments challenge the metallic interconnector (MIC) of solid oxide fuel cells with high‐temperature oxidation, interfacial reactions, and persistent Cr 6+ volatilization. Notably, high p (H 2 O) in the anode environment would further accelerate the Cr volatilization and confront the MIC with non‐negligible oxidation issues. We systematically investigated three CeO 2 ‐coated MIC (AMIC 21/SUS 443/Crofer 22H)//anode systems during long‐term operation under 700°C@90% H 2 –10% H 2 O conditions. Key findings reveal that both the sputtering pressure and deposition temperature significantly enhance CeO 2 grain size and crystallinity. Among the three systems, CeO 2 /Crofer 22H demonstrates superior oxidation resistance, characterized by minimal oxide growth (52.6 nm kh −1 ). However, CeO 2 /SUS 443 achieved the lowest ASR increase rate of 13.4% kh −1 , outperforming CeO 2 /AMIC21 (48.8% kh −1 ) or CeO 2 /Crofer 22H (46.7% kh −1 ). After assembling with Ni‐GDC anode, final interface resistances of 32.6, 31.1, and 27.4 mΩ cm −2 were achieved for Ni‐GDC//CeO 2 /AMIC21, Ni‐GDC//CeO 2 /SUS 443, and Ni‐GDC//CeO 2 /Crofer 22H. This work demonstrates that CeO 2 coating exhibits not only excellent compatibility and interfacial stability with the Ni‐based anode but also maintains stable conductivity and provides effective protection under MIC/anode service conditions.