Ni/C Slurries Based on Molten Carbonates as a Fuel for Hybrid Direct Carbon Fuel Cells

Ni-impregnated carbon black (Ni/XC-72R) was tested as a fuel for a hybrid direct carbon fuel cell (HDCFC) with a hybrid electrolyte of yttria-stabilized zirconia and molten carbonate (Li2CO3/K2CO3). The open-circuit voltage (OCV) of the HDCFC with Ni/XC-72R was quite high, about 1.5 V at 700 degrees C. The maximum power density was improved by factors of 7.6 and 3.1, respectively, at 550 and 700 degrees C by adding 50 wt % of Ni catalyst. The effect of the Ni catalyst on the carbon/carbonate slurry was investigated by temperature-programmed decomposition. The Ni catalyst probably contributes to the high OCV by enhancing the reverse Boudouard reaction (C+CO2 -> 2CO) in the carbon/carbonate slurry in the HDCFC.