Highly active and durable double-doped bismuth oxide-based oxygen electrodes for reversible solid oxide cells at reduced temperatures

Abstract

Sluggish reaction kinetics on oxygen electrodes at reduced temperatures (< 750 C) remain amajor challenge for the technical progress of reversible solid oxide cells (SOCs). To overcome this issue, the development of highly active and stable oxygen electrodes at intermediate temperatures (ITs, < 750 C) is urgent and essential. Rare earth- stabilized bismuth oxides are known to have high ionic conductivity and fast oxygen surface kinetics. Despite these advantageous properties, unlike conventional zirconia- or ceria- based materials, stabilized bismuth oxides have not been widely investigated as oxygen electrode components for reversible SOC applications. Herein, using the double doping strategy, we successfully developed Dy and Y co- doped Bi2O3 (DYSB), which showed recordhigh conductivity, 110 times higher than that of yttria- stabilized zirconia (YSZ) at ITs. This DYSB combined with conventional La0.8Sr0.2MnO3 d (LSM) significantly enhanced surface diffusion and incorporation of oxygen ion kinetics during the oxygen reduction reaction (ORR). Finally, the novel LSM- DYSB oxygen electrode was simply embedded in a YSZ electrolyte- based cell without a buffer layer. The LSM- DYSB SOC yielded an extremely high performance of 2.23 W cm 2 in fuel cell mode as well as 1.32 A cm 2 at 1.3 V in electrolysis mode at 700 C, along with excellent long- term and reversible stabilities. This study demonstrates that the novel DYSBbased electrode has great potential as a high- performance oxygen electrode for next generation SOCs and provides new insight into rational design andmaterial selection for solid state energy conversion and storage applications.