Oxidation Behavior of Carbon in a Coin-Type Direct Carbon Fuel Cell

To date, carbon oxidation in high temperature fuel cells has been classified into two processes: one involves direct oxidation to CO(2) [direct electrochemical process] and the other involves oxidation to CO(2) via a chemical species of CO [chemical-electrochemical (CE) process]. A coin-type direct carbon fuel cell was fabricated on the basis of molten carbonate fuel cell technology. Activated carbon made from bamboo was used as the fuel. Steady state polarization and step chronopotentiometry methods were employed at 850 degrees C. The results strongly suggested that carbon oxidation was initiated by chemical oxidation to CO, which was then oxidized to CO(2) electrochemically. Gas generation reached a steady state in about 10 min. Step chronopotentiometry was found to be an effective tool for the kinetic investigation of the carbon oxidation. The carbon oxidation behavior was very similar to the oxidation of gaseous CO. This also supports the CE process for solid carbon oxidation. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3544941]