Preparation and Performances of Tubular Cone-shaped Anode-supported Segmented-in-series Direct Carbon Solid Oxide Fuel Cell

To solve the problem of large concentration polarization impedance of anode-supported direct carbon solid oxide fuel cell (DC-SOFC), tubular cone-shaped anode-supported segmented-in-series solid oxide fuel cell (SOFC) was prepared by an improved gel-casting method. By appropriately increasing content of the solvent, fluidity of the slurry and quality of the obtained product were improved. By increasing content of the pore-forming agent, the porosity of the anode was increased, reducing the diffusion resistance of gas. As-improved SOFC was fueled by hydrogen and operated at 800 degrees C with an open-circuit voltage of 1.05 V. The polarization impedance of the electrochemical impedance spectrum decreased while the maximum power density was 0.67 W.cm(-2) and the active area of the cathode was 2.2 cm(2). These SOFC electrochemical performances were significantly higher than that before improvement. Activated carbon loaded on the anode with 5% (in mass) K as catalyst was directedly used as the fuel of SOFCs. Using this anode-supported direct carbon, the DC-SOFC was prepared, showing an open circuit voltage of 1.030 V and a peak power density of 0.74 W. cm(-2) at 800 degrees C. This DC-SOFC was discharged at a constant current of 400 mA, and its effective utilization rate of carbon fuel was 31% which was higher than that before improvement (17%). Four improved tubular cone-shaped single cells were connected in series to form a four-cell stack, showing a peak power of 8.0 W and a corresponding power density of 0.91 W.cm(-2) at 800 degrees C, which was higher than that before improvement (4.1 W), exceeding the maximum of previous reported DC-SOFC, and displayed an effective utilization rate of 15% for carbon fuel.