Chromium deposition and interfacial interactions of an electrolyte–air electrode-interconnect tri-layer for solid oxide fuel cells

In solid oxide fuel cell operation, electrical current plays an important role in the air electrode interaction with electrolyte and interconnect and long-term cell performance. In this study, (La0.8Sr0.2)xMnO3 (LSM) air electrodes with different stoichiometries (x = 0.95, 1, and 1.05) are fabricated on the surface of yttria stabilized zirconia (YSZ) and then sandwiched with AISI 441 stainless steel interconnect. The simulated half cells are thermally treated at 800 °C for 500 h under a 200 mA cm−2 current density in dry air. YSZ/LSM interfacial interaction and the reaction of volatile chromium species on the LSM surface are characterized. Different LSM stoichiometry leads to different interfacial reactions and Cr deposition amounts. Mn is a critical species for the Cr deposition under polarization. Excessive Mn in LSM lessens the formation of La-containing phase at the YSZ/LSM interface and accelerates Cr deposition. Deficient Mn in LSM leads to extensive interfacial reaction with YSZ, forming more La-containing phase and inhibiting Cr deposition.

► Electric current is a critical factor for fuel cell material degradation. ► (La0.8Sr0.2)xMnO3 leads to different interfacial reactions and Cr deposition. ► Excessive Mns lows La-related phase formation but accelerates Cr deposition. ► Deficient Mn causes extensive interfacial reaction and La-related phase formation. ► Deficient Mn desirably inhibits Cr deposition.