Direct methanol fuel cell (DMFC) based on PVA/MMT composite polymer membranes

A novel composite polymer electrolyte membrane composed of a PVA polymer host and montmorillonite (MMT) ceramic fillers (2-20 wt.%), was prepared by a solution casting method. The characteristic properties of the PVA/MMT composite polymer membrane were investigated using thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), scanning electron microscopy (SEM), and micro-Raman spectroscopy, and the AC impedance method. The PVA/MMT composite polymer membrane showed good thermal and mechanical properties and high ionic conductivity. The highest ionic conductivity of the PVA/10 wt.%MMT composite polymer membrane was 0.0368 S cm^-1 at 30 °C. The methanol permeability (P) values were 3-4 × 10^-6 cm² s^-1, which was lower than that of Nafion 117 membrane of 5.8 × 10^-6 cm² s^-1. It was revealed that the addition of MMT fillers into the PVA matrix could markedly improve the electrochemical properties of the PVA/MMT composite membranes; which can be accomplished by a simple blend method. The maximum peak power density of the DMFC with the PtRu anode based on Ti-mesh in a 2 M H₂SO₄ + 2 M CH₃OH solution was 6.77 mW cm^-2 at ambient pressure and temperature. As a result, the PVA/MMT composite polymer appears to be a good candidate for the DMFC applications.