Effect of Calcium Hydroxy Phosphate as a Crystallinity Enhancer in Nafion Membrane for Direct Methanol Fuel Cell

Abstract

Nafion is a widely used membrane in direct methanol fuel cell (DMFC). Many advantages of Nafion including good chemical stability, good thermal resistance, and high proton conductivity. However, Nafion has high methanol crossover which remarkably reduces the performance of DMFC and results in waste of fuel. Therefore, in this work, calcium hydroxy phosphate (CHP) was incorporated into Nafion to increase its crystallinity. The properties of Nafion/CHP such as crystallinity, water uptake, ion exchange capacity, methanol crossover, and solubility were studied. SEM/EDS with elemental mapping was used to observe the dispersion of CHP within the membrane. It was clearly shown that by incorporating 1.0 wt% and 2.5 wt% of CHP into the membrane, methanol crossover at 30 C was reduced from 125.6 x 10-6 cm2s-1 to 2.58 x 10-6 cm2s-1 and 65.58 x 10-6 cm2s-1. The reduction of methanol crossover of CHP/Nafion composite membrane at higher weight was lesser than that of the composite at lower weight due to the agglomeration of CHP.