Effect of CeO2 Infiltration on the Hybrid Direct Carbon Fuel Cell Performance

The concept of Hybrid Direct Carbon Fuel Cell (HDCFC) uses a mixture of solid carbon with (Li-K-Na) carbonates, which melt at operating temperature, fed on top of a solid oxide anode. This setup offers several advantages: the presence of carbonates helps both to increase the contact between the solid carbon and the solid oxide electrode and to extend the electrolyte into the solid carbon. Furthermore the HDCFC allows the use of the current SOFC configuration, like commercial anode supported cells.

In this study the performance of anode supported NiO/YSZ│YSZ│LSM/YSZ cells towards direct carbon oxidation has been measured. Particularly, the effect of both CeO₂ infiltration into the NiO/YSZ anode and CeO₂ infiltration of solid carbon have been investigated between 750°C and 815°C  through the use of polarization curves and electrochemical impedance spectroscopy (EIS). The impedance spectra are modeled and discussed with the objective to study the effect of CeO₂ infiltration on the processes dominating the impedance response of the anode.

Figures 1 and 2 show the Nyquist plots of the impedance spectra for the CeO₂ infiltrated anode cell and the blank cell, respectively. The spectra were recorded at open circuit potential at 815°C, 800°C and 760°C in the presence of 96% N₂ and 4% CO₂.