Analytical Model for Effect of Polymer Composite Membrane Properties on Direct Methanol Fuel Cell Performance

Abstract. Performance of direct methanol fuel cell (DMFC), using polymer composite membrane, can be directly affected by membrane properties, including permeability, proton conductivity and membrane thickness. In order to obtain high DMFC performance, methanol permeability of the membrane should be low, while keeping high proton conductivity. This may be achieved by modification of incorporating inorganic filler into high proton conducting membrane. In this work, the analytical modeling for DMFC performance prediction was developed to be a guideline for Nafion based membrane improvement. Methanol permeability and proton conductivity were set at 0.30 – 5.60 cm2×S-1 and 0.08 – 0.15 S×cm-1 with the thickness of 25 – 1000 μm. The results show that DMFC performance strongly depends on the methanol permeability especially with thin membrane giving maximum power density of 1034 and 100mW×cm-2 at the permeability of 0.30 and 5.60 cm2×S-1, respectively, with thickness of 45 μm, while with thick membrane the permeability has negligibly effect. However, the proton conductivity mainly affects DMFC performance only with thick membrane as a result of ohmic resistance.