High performance intermediate temperature micro-tubular SOFCs with Ba0.9Co0.7Fe0.2Nb0.1O3−δ as cathode

In this study, anode supported intermediate temperature micro-tubular solid oxide fuel cells (MT-SOFCs) have been fabricated by combination of phase-inversion, dip-coating, co-sintering and printing method. The MT-SOFC consists of a ∼300 μm wall-thickness Ni–Sc₂O₃ stabilized ZrO₂ (ScSZ) anode tube, ∼10 μm ScSZ dense electrolyte layer, ∼10 μm Ce_0.9Gd_0.1O_2−δ (GDC) membrane buffer layer and ∼50 μm Ba_0.9Co_0.7Fe_0.2Nb_0.1O_3−δ (BCFN) cathode layer. SEM and electrochemical impedance spectroscopy (EIS) analysis suggested that the novel structured anode can remarkably diminish the porous anode geometrical tortuosity and improve the fuel gas diffusivity. High peak power densities of 0.34, 0.51 and 0.72 W cm⁻² have been achieved with humidified hydrogen as the fuel and ambient air as oxidant at 550, 600 and 650 °C, respectively. Further, the cell has demonstrated a very stable performance with no significant cell voltage degradation under a constant current of 0.6 A cm⁻² for over 213 h test at 650 °C.