Tubular direct carbon solid oxide fuel cells with molten antimony anode and refueling feasibility

•YSZ electrolyte-supported tubular SOFCs are fabricated.•Cell performance is evaluated with molten Sb anode and carbon fuel.•Feasibility of refueling the tubular cell is demonstrated.

Tubular direct carbon SOFCs (solid oxide fuel cells) supported by YSZ (Y2O3 stabilized ZrO2) electrolyte are fabricated by slurry-casting, slurry-dipping and sintering processes with La0.6Sr0.4Co0.2Fe0.8O3-10 mol.% Gd2O3 doped CeO2 (LSCF-10GDC) as the cathode. Their electrochemical performance is examined at temperatures from 700 to 800 °C using molten antimony (Sb) anode and activated carbon fuel. The ohmic resistance of the cell is between 1.01 and 0.37 Ω cm2 mainly originated from the thick YSZ electrolyte (150 μm); the polarization resistance ranges from 0.22 to 0.06 Ω cm2. The maximum power density at 800 °C is 304 mW cm−2 and can be greatly increased by using a thinner and/or more conductive electrolyte. With 1 g activated carbon as the fuel, the cell performance is stable at 200 mW cm−2 at 800 °C for more than 6 h by chemical consumption (oxidization) of the carbon, which reduces the electrochemically formed Sb2O3 to Sb. The cell performance decreases as the fuel is used up and is recovered by refueling.