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Oxygen-electrode-supported solid oxide cells (OESCs) have potential advantages over fuel-electrode-supported cells, including reduced fuel-electrode concentration polarization, better oxygen electrode current collection, and flexibility in the fuel electrode choice. However, there are serious drawbacks including the difficulty of co-firing the oxygen electrode and electrolyte, and oxygen electrode concentration polarization. This paper explores the characteristics of OESCs with La0.8Sr0.2MnO3-d-Zr0.92Y0.16O2-d (LSM-YSZ) electrode-support enhanced by SrTi0.3Fe0.6Co0.1O3-d (STFC) infiltration, thin YSZ electrolyte, and SrTi0.3Fe0.7O3-d (STF) fuel electrodes. The STFC infiltration increases fuel cell maximum power density by >1.5 times and electrolysis current density (at 1.3 V) by >2 times. Cell performance in pure oxygen is compared to that in air, exploring a possible reversible solid oxide cell system configuration where oxygen produced during electrolysis is stored and subsequently used during fuel cell operation. The fuel cell maximum power density is increased from 0.88 W cm-2 in air to 1.37 W cm-2 in oxygen, with limiting current increased from 1.7 to >5.6 A cm-2; the electrolysis performance is essentially unchanged, probably because the electrode air becomes enriched with oxygen during electrolysis. [ABSTRACT FROM AUTHOR]

In order to assess the durability of La0.6Sr0.4Co0.2Fe0.8O3 oxygen electrodes in reversible solid oxide cells, current switched ~1000 h galvanostatic (0.7, 1.0, and 1.5 A/cm²) life tests were performed on symmetrical Ce0.9Gd0.1O2-electrolyte cells at 700±C. Cell operating voltage and resistance, the latter measured by impedance spectroscopy, were monitored throughout. Degradation was minimal for the 0.7 A/cm² case. For the higher current densities, the cell voltage and resistance increased with time, although the cell appeared to stabilize after ~500 h in the 1.5 A/cm² case. Post-test analyses showed no evidence of electrolyte cracking or delamination for any current. However, 3D imaging revealed measureable microstructural coarsening after 1.5 A/cm² operation that was not present after 0.7 A/cm² operation. Furthermore, the amount of Sr segregated onto LSCF surfaces was higher for the cells operated with current switching versus the as-prepared and zero-current cells. Analysis of the results suggest that much of the degradation was due to decreased oxygen surface exchange rate due to current-enhanced Sr segregation, with a smaller contribution due to microstructural coarsening. The possibility of extrapolating these accelerated tests to longer times is discussed. [ABSTRACT FROM AUTHOR]