Influence of Reactions of Carbon Black and Fuel Diffusion Process on Power Generation Characteristics of Rechargeable Solid Carbon Fuel Cells(RSCFCs)

Abstract

Rechargeable Solid Carbon Fuel Cells (RSCFCs) that use directly supplied carbon black (CB) as fuel were developed. The influence of the CO supply rate depended on the CO generation rate and the CO diffusion rate on the power generation was investigated. High power density was achieved by using a larger specific surface area CB fuel due to the increase in CO generation rate. Two types of cell setting were evaluated, horizontal and vertical setting. With horizontal cell setting, densely supplied CB enhanced the power density because the increase in the CO generation rate was greater than the decrease in CO diffusion rate due to the increase of CB surface area per unit column volume. However, CB supply density should decrease during the power generation due to the CB consumption by Boudouard corrosion reaction. In contrast, with the vertical cell setting, CB supply density must be almost constant because CB maintains contact with the anode surface by its own weight. Moreover, the performance of RSCFC was improved by using anode with high porosity. With 27 % porous anode, the maximum power density (PMax ) was 24.1 mW/cm2 at 50 mA/cm2, and with 33 % porous anode, the PMax was 34.6 mW/cm2 at 70 mA/cm2. The total TPB (Triple Phase Boundary) length in anode might be decreased with increasing porosity of anode, but the power density of RSCFC with CB fuel was increased.