(605g) Performance of a First-Generation Biocarbon Fuel Cell

We studied the performance of an aqueous-alkaline fuel cell system that used biocarbon (i.e., carbonized charcoal) as a fuel. As a pretreatment, we carbonized Flash Carbonization^TM charcoal at 900 – 1050 °C for 30 min, which caused a reduction of its electrical resistivity. Subsequently we compressed the charcoal at 38 MPa to form a carbon bed and used it as an anode electrode. The charcoal anode showed a low resistivity that was comparable to that of graphite electrodes. We used a Pt foil/Ag screen assembly as a cathode (oxygen reduction) and various aqueous-alkaline solutions as an electrolyte. To study the cell performance above 100°C, the fuel cell apparatus was operated in a pressure vessel (up to 3.58 MPa).

In the last meeting, we reported the effect of the cathode configuration and the performance at low temperatures. In this meeting we will report the effect of cell temperature, electrolyte composition, anode size and composition, etc. upon the fuel cell performance (open circuit voltage, short circuit current density, and maximum power). We found that the presence of Li⁺ ion in the electrolyte enhances the cell performance. The performance improved as the cell temperature was increased, and at 245°C using 6 M KOH/1 M LiOH mixture as the electrolyte, the cell showed the open circuit voltage of 0.57 V, short circuit current density of 44 mA/cm², and maximum power of 19 mW.