Magnesia phosphate cement composite bipolar plates for passive type direct methanol fuel cells

Abstract

Bipolar plates composed of magnesia phosphate cement composite were fabricated via hot-press assisted hydration process. Techniques, including open circuit potential-time, alternating current impedance, and linear sweep voltammetry, were applied to the bipolar plates to investigate their electrochemical properties through both single cell and fuel cell stack at 70–90 °C. The results indicated that the bipolar plates achieved stable and uniform performance. Specifically, the fuel cell stack composed of three single cells in series achieved a maximum current density of 79.78 mA/cm2 and a peak power density of 25.54 mW/cm2 at 80 °C. A good and cyclable performance of the fuel cell devices using the magnesia phosphate cement based bipolar plates was observed in the switch on/off test. Then, an operation of 3.5 h was achieved under a current density of 25 mA/cm2 during the fuel availability test. The after-test investigation suggested that the surface reinforcement of the bipolar plates might improve the performance of long term operation. In conclusion, magnesia phosphate cement composite bipolar plates are suitable for direct methanol fuel cells.