Synergistic thermal expansion reduction in cobalt-containing perovskite cathodes for solid oxide fuel cells

Synergistic thermal expansion reduction in cobalt-containing perovskite cathodes for solid oxide fuel cells

SrCoO3-δ -based cathodes, such as Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF), exhibit high oxygen reduction reaction (ORR) activity, making them strong candidates for solid oxide fuel cells (SOFCs). However, their high thermal expansion leads to significant mechanical degradation during thermal cycling, hindering their broader application. In this study, we introduced a synergistic strategy by incorporating negative thermal expansion material Sc2W3O12 (ScWO) into BSCF to reduce the overall thermal expansion of composite cathode. The thermal expansion offset strategy together with the suppression of cobalt reduction at the elevated temperature, contributes for maintaining thermal compatibility in cobalt-based cathode and the cathode/electrolyte interface. Over 40 thermal cycles between 600 and 300oC, BSCF showed more than 100 % ASR degradation, while the composite cathode demonstrated just 18 % degradation, indicating enhanced thermal cycling resistance. Microstructural analysis using FIB-SEM revealed approximately 140 % relative porosity increase in BSCF due to microcracking. In contrast, negligible porosity change was observed in the composite cathode, confirming the benefit to the overall structural integrity.