Improvement of Fe addition on redox stability of Ni/YSZ composite anode for intermediate temperature solid oxide fuel cell

Solid oxide fuel cell (SOFC) is configurated to generate electricity from renewable sources with high efficiency and low emission, and considered as promising alternative to traditional thermal power generation. But the Nibased anode of this device suffers from redox cycles, which limits its development and application. In this study, a modified Ni-Fe/YSZ anode is proposed to improve the redox stability and compared with typical Ni/YSZ anode. The two anodes achieve output power densities as 0.58 W/cm2 and 0.56 W/cm2 for Ni/YSZ and Ni-Fe/YSZ at 750 degrees C in H2 respectively. The Ni-Fe/YSZ anode can endure 10 redox cycles, while the Ni/YSZ anode shows a structural failure after 2 cycles. Furthermore, the electrochemical performance of Ni-Fe/YSZ supported cell increases during redox cycles, which is proved to be related to the decrease of anode concentration polarization by DRT analysis. The effect of Ni-Fe/YSZ anode on the improvement of redox stability can be attributed to the higher oxidation resistance of Ni-Fe alloy. A plausible mechanism is proposed to illustrate the effect of Ni-Fe alloy on the improvement of redox stability, which can be attributed to the effective inhibition of Kirkendal effect by Fe during Ni oxidation, thus reducing the dimensional expansion of Ni/YSZ anode.