Studies on composite proton exchange membranes made from poly(vinyl alcohol-co-styrenesulfonic acid)/non-woven fabric for direct methanol fuel cell

Abstract

Various materials have been examined over the last several decades to fabricate proton exchange membranes (PEMs) for direct methanol fuel cells (DMFCs), with the objective of achieving high selectivity (i.e., the ratio of proton conduction to fuel permeability). Ideally, a PEM for DMFC must demonstrate higher proton conductivity, as well as lower methanol permeability, in comparison to the commercial Nafion membranes. With these objectives, this research paper reports the fabrication of a composite PEM comprising glutaraldehyde-crosslinked poly(vinyl alcohol-co-styrenesulfonic acid) and sulfonated polypropylene-based non-woven fabric (S-NWF) by deep coating technique. The resulting PEMs were thoroughly characterized to find physicochemical and electrochemical properties. Key findings obtained with these composite PEMs are (a) exhibition of dimensional stability in hot water (at 80 °C), (b) improved proton conductivity (i.e., 0.12 S·cm–1 at 80 °C), and reduced methanol permeability (i.e., 3.91·10–8 cm2·s–1) upon increasing the number of coating layers on the S-NWF, (c) achievement of a membrane selectivity value of 2.61·106 S·s·cm–3, and (d) the fact that 6 layers of coating resulted in producing the highest peak power density of 62.32 W·m–2 and a current density of 540 A·m–2.

Keywords

• polymer membranes
• direct methanol fuel cell
• proton exchange membrane
• composite membrane electrolyte
• poly(vinyl alcohol-co-styrenesulfonic ac