Sulfonated poly(2,6-Dimethyl-1,4-phenylene oxide)composite membrane filled by zeolite for direct methanol fuel cell

Abstract

Composite membranes were fabricated as a proton exchange membrane (PEM) for direct methanol fuel cell (DMFC). Sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO) membrane was prepared by solvent casting. SPPO was subsequently mixed with various contents of zeolite Y to fabricate the composite membranes. The properties of the pristine and composite membranes were characterized by Fourier Transform Infrared spectroscopy (FTIR), Thermogravimetry analysis (TGA), LCR meter, and Gas Chromatography (GC) techniques. The effects of degree of sulfonation and zeolite Y contents were systematically varied to tailor the PEM properties (proton conductivity, methanol permeability, membrane selectivity) in DMFC application. A SPPO/zeolite Y composite membrane at 31% degree of sulfonation with 0.1%v/v of zeolite Y filling exhibits the highest membrane selectivity, defined as the ratio of proton conductivity to methanol permeability, of 6.02x10⁴ S.s/cm³, which is 1.43 times higher than the membrane selectivity of Nation 117 which is 4.20x10⁴ S.s/cm³.