A direct carbon solid oxide fuel cell stack on a single electrolyte plate fabricated by tape casting technique

A four-cell-in-series stack of solid oxide fuel cell is fabricated on a single yttrium-stabilized-zirconia electrolyte plate which is fabricated by tape casting technique. The slurry for the tape casting process is characterized and optimized through Zeta potential and viscosity measurements. The optimal slurry is used to prepare the electrolyte plate, with electrical connecting holes, for the stack. The stack is operated directly with 5 wt% Fe-loaded activated carbon as the fuel. With a total effective area of 8.8 cm2 and carbon fuel of 5 g, this direct carbon solid oxide fuel cell stack shows an open circuit voltage of 3.82 V and an output power of 2.2 W at 820 °C. It gives a discharging platform of over 3.0 V for 10.5 h with a constant discharging current of 200 mA, at 800 °C. Then voltage drops to zero after discharging for 14 h, releasing a discharging energy of 8.6 W h. This work shows a possibility of developing direct carbon solid oxide fuel cells for applications of portable or distributed power sources.