A direct methanol fuel cell using acid-doped polybenzimidazole as polymer electrolyte

A direct methanol/oxygen solid polymer electrolyte fuel cell was demonstrated. This fuel cell employed a 4 mg cm(-2) Pt-Ru alloy electrode as an anode, a 4 mg cm(-2) Pt black electrode as a cathode and an acid-doped polybenzimidazole membrane as the solid polymer electrolyte. The fuel cell is designed to operate at elevated temperature (200 degrees C) to enhance the reaction kinetics and depress the electrode poisoning, and reduce the methanol crossover. This fuel cell demonstrated a maximum power density about 0.1 W cm(-2) in the current density range of 275-500 mA cm(-2) at 200 degrees C with atmospheric pressure feed of methanol/water mixture and oxygen. Generally, increasing operating temperature and water/methanol mole ratio improves cell performance mainly due to the decrease of the methanol crossover. Using air instead of the pure oxygen results in approximately 120 mV voltage loss within the current density range of 200-400 mA cm(-2).