In Situ Formation of Er_0.4Bi_1.6O₃ Protective Layer at Cobaltite Cathode/Y₂O₃–ZrO₂ Electrolyte Interface under Solid Oxide Fuel Cell Operation Conditions

Abstract

Bismuth based oxides exhibit outstanding oxygen ionic conductivity and fast oxygen surface kinetics and have shown great potential as a highly active component for electrode materials in solid oxide fuel cells (SOFC). Herein, a Nb-doped La0.6Sr0.4Co0.2Fe0.7Nb0.1O3-δ (LSCFNb) electrode with 40% Er0.4Bi1.6O3 (ESB) composite electrode was successfully fabricated by decoration method and directly assembled on barrier-layer-free yttrium stabilized zirconia (YSZ) electrolyte cells, achieving a peak power density of 1.32 W cm-2 and excellent stability ACS Applied Materials and Interfaces. 10 (47): 40549-40559 (2018). 2 at 750 o C and 250 mAcm-2 for 100 hrs. ESB decoration also significantly reduces the activation energy from 214 kJ mol-1 for the O2 reduction on pristine LSCFNb electrode to 98 kJ mol-1. Further microstructural analysis reveals that there is a redistribution and migration of the ESB phase in the ESB-LSCFNb composite towards the YSZ electrolyte under the influence of cathodic polarization, forming a thin ESB layer at the cathode/YSZ electrolyte interface. The in situ formed ESB layer not only prevents the direct contact and subsequent reaction between segregated SrO and YSZ electrolyte, but also remarkably promotes the oxygen migration/diffusion at the interface for O2 reduction reaction, resulting in a remarkable increase in power output and decrease in activation energy. The present study clearly demonstrated the in situ formation of a highly functional and active ESB protective layer at LSCFNb cobaltite cathode and YSZ electrolyte interface via ESB decorated LSCFNb composite cathode under SOFC operation conditions.

Surface Segregation in Solid Oxide Cell Oxygen Electrodes: Phenomena, Mitigation Strategies and Electrochemical Properties

“…of Nb-doped La 0.6 Sr 0.4 Co 0.2 Fe 0.7 Nb 0.1 O 3−δ (LSCFNb) electrodes directly assembled on barrier layer-free YSZ electrolyte cells, achieving a peak power density of 1.32 W cm −2 and excellent stability at 750 °C and 250 mA cm −2 for 100 h[303]. Here, these results indicate the redistribution and migration of the ESB phase in the ESB-LSCFNb composite towards the YSZ electrolyte under the influence of cathodic polarization and the formation of a thin ESB layer at the cathode/YSZ electrolyte interface (Fig.19).…”

Nano-CeO2-Modified Cathodes for Direct Electrochemical CO2 Reduction in Solid Oxide Electrolysis Cells

“…Electrochemical impedance spectroscopy (EIS) at open circuit voltage (OCV) and 1.4 V for the cells is shown in Figure a,b, respectively. From Figure a, all of the cells have a similar ohmic resistance (the first intersection of the X axis (Z′′ = 0)), which consists of the ohmic resistance of the electrolyte, electrodes, leads, and the interfacial contact resistance (mainly resulting from the O 2– transportation between electrode and electrolyte). − At OCV, the decrease in R p (the distance between the second intersection and the first intersection of the X axis) after the impregnation of CeO 2 nanoparticles reflects the fact that the impregnated cathode has a stronger ability to adsorb CO 2 , as shown by the results of CO 2 -TPD. In Figure b, the total resistance values (the second intersection of the X axis, R tot ) of the cells after the impregnation of CeO 2 nanoparticles are smaller than for the conventional cathode.…”

A critical review of the nano-structured electrodes of solid oxide cells

“…In another study, the directly assembled ESB-La 0.6 Sr 0.4 Co 0.2 Fe 0.7 Nb 0.1 O 3− δ (LSCFN) composite electrode has exhibited outstanding ORR performance and stability. 61 It was revealed that cathodic polarization induced the generation of a thin ESB layer at the interface after the stability test, as shown in Fig. 10.…”