Effect of counter diffusion of CO and CO2 between carbon and anode on the performance of direct carbon solid oxide fuel cells

Abstract A direct carbon solid oxide fuel cell converts the chemical energy of carbon directly to electricity through the coupling of electrochemical oxidation of CO at the anode and the reverse Boudouard reaction at the carbon fuel. The counter diffusion of CO and CO2 between the carbon and the anode plays an important role on the performance of direct carbon solid oxide fuel cells. Here we select the distance between the carbon and the anode as the parameter to characterize the effect of the counter diffusion of CO-CO2 on the performance of cells. Planar yttrium-stabilized-zirconia electrolyte-supported solid oxide fuel cells are prepared with a cermet of silver and gadolinium-doped ceria as the material for both of anode and cathode. Fe-loaded activated carbon is directly used as the fuel of the cells. Electrochemical performances of the direct carbon solid oxide fuel cells, with distance as 0, 4, 7, 10, and 13 mm, are tested at 700 °C, 800 °C and 850 °C, respectively. Experimental results show that the performance of the cells decrease with increasing distance. Mechanism of the performance degradation is analyzed in detail.