Degradation and recovery of La_0.6Sr_0.4Co_0.2Fe_0.8O₃-based intermediate-temperature reversible solid oxide cells by controlled surface acidity

The main challenge for commercializing reversible solid oxide fuel and electrolysis cells (r-SOC) is improving their performance, and long-term durability, the latter, in part, by reducing their operating temperatures. Cr poisoning is one of the main factors contributing to degraded air electrode performance over time, so the stable long-term operation of r-SOCs requires a strategy to solve this problem. We apply acid/base engineering and demonstrate that it is capable of markedly reducing Cr poisoning-induced degradation of (La, Sr)(Co, Fe)O₃ (LSCF), recognized particularly as high-performance air electrodes for intermediate temperature (IT) reversible cells. We find that subsequent infiltration of basic additives effectively restores the ∼20-fold increase in polarization resistance induced by initial Cr infiltration and poisoning. In addition, acid/base engineering was confirmed, for the first time, to strikingly impact, as well, the operation of reversible cells in both fuel cell and electrolysis cell modes. This study emphasizes the magnified challenges for operating at reduced temperatures, given the markedly enhanced potential for Cr poisoning and the role that acid/base engineering can play in overcoming these challenges. Also addressed are challenges for higher temperature operation of r-SOCs and the means for addressing them, thereby ensuring stable, longer-term operation.