Development of tungsten stabilized SrFe0.8W0.2O3-δ material as novel symmetrical electrode for solid oxide fuel cells

Abstract

The SrFe0.8W0.2O3-δ (SFW) perovskite oxide which is prepared by a modified citrate-EDTA-nitrate combustion method is developed as an electrode material for symmetrical solid oxide fuel cell (SSOFC). The tungsten dopant can stabilize the cubic perovskite structure of SrFeO3 and increase the resistance to the reducing atmosphere, demonstrating its great potential as an alternative SOFC anode. Meanwhile, the electro-catalytic activity of SFW as SSOFC electrode is intensively studied. Area specific polarization resistances (ASRs) of SFW based on SSOFC with La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM) electrolyte at 800 °C are measured to be as low as 0.084 and 0.20 Ω cm2 in air and H2, respectively. The combined analysis of electrochemical impedance spectra (EIS) and distribution of relaxation times (DRT) of SFW electrode process reveals that the rate-limiting step in the anodic condition is associated with the hydrogen adsorption/dissociation process at SFW surface, while in the cathodic condition is ascribed to dissociation of adsorbed oxygen and charge transfer processes. LSGM electrolyte-supported SSOFC with SFW electrode exhibits a high power density of 931 mW cm−2 and a low polarization resistance of 0.075 Ω cm2 at 850 °C when using hydrogen as fuel gas and air as the oxidant, indicating that SFW is a promising SSOFC electrode material.