Effect of polymer sulfonation on the proton conductivity and fuel cell performance of polyvinylalcohol‐mordenite direct methanol fuel cell membranes

Abstract

Sulfonated polyvinylalcohol‐mordenite (SPVA‐MOR) membranes for direct methanol fuel cell use were synthesized and characterized. It had earlier been found out that polyvinylalcohol‐mordenite (PVA‐MOR) membranes, while having excellent methanol permeability and modest proton conductivity values, had inferior direct methanol fuel cell performances than Nafion™. Sulfonating the polyvinylalcohol matrix had been suggested to improve the proton conductivity. In this work, polyvinylalcohol powder was sulfonated by using propane sultone as the sulfonating agent prior to the membrane synthesis. Morphological analyses revealed that the zeolite particles mixed homogeneously within the polymer matrix. Sulfonating the polymer slightly decreased both water and methanol uptakes. Both in PVA‐MOR and SPVA‐MOR membranes, water uptake turned out to be higher than the methanol uptake. SPVA‐MOR membranes were found to have an average proton conductivity of 0.052 S·cm−1 when compared with the 0.036 S·cm−1 of PVA‐MOR membranes, while Nafion™ has a proton conductivity of approximately 0.1 S·cm−1. The increase in the proton conductivity upon sulfonation despite the decrease in water uptake was explained by the dominance of the Grotthuss mechanism over the vehicular mechanism for proton conductivity. Fuel cell test results showed that while SPVA‐MOR membranes cannot outperform Nafion™, they give higher power output than PVA‐MOR membranes, especially at low temperatures and high methanol concentrations. © 2017 Curtin University of Technology and John Wiley & Sons, Ltd.

Enhanced performance of Mindel membranes by incorporating conductive polymer and inorganic modifier for application in direct methanol fuel cells

“…In recent decades, researchers devoted their attention to the development of low‐cost, high‐performance PEMs for fuel cell applications 3–7 . Sulfonated polyethersulfone (SPES), 4,5 sulfonated poly(ether ether ketone) (SPEEK), 6–9 sulfonated polysulfone, 3,10,11 sulfonated poly(aryl ether ether ketone ketone)s, 12 sulfonated poly(ether ketone ketone), 13 and so on have been utilized for the preparation of PEMs owing to their outstanding mechanical properties, thermal stability, and conductivity and also to overcome the disadvantages of PFI membranes 6–13 …”

Evaluation of transport mechanism and nanostructure of nonperfluorinated PVA/sPTA proton exchange membrane for fuel cell application

“…Because the formation of water clusters creates ionic routes for the transit of protons from the anode to the cathode, a relatively high value of water uptake ( W ) is required to achieve adequate proton conductivity. Uctug et al 29 proposed a hypothesis to explain the reason for the decrease in water uptake. They account for the anomalous reduction of water uptake to sulfonic groups (—SO 3 H) immobilization of PVA membrane.…”

“…This tendency validates the blocking effect explanation (decreased sites that take up water) as a result of the chemical reaction between achieve adequate proton conductivity. Uctug et al 29 proposed a hypothesis to explain the reason for the decrease in water uptake.…”

Non‐fluorinated PVA/SSA proton exchange membrane studied by positron annihilation technique for fuel cell application

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