Fabrication and electrochemical properties of SPVdF-co-HFP/SPES blend proton exchange membranes for direct methanol fuel cells

Highlights

PEMs based on SPVdF-co-HFP and SPES were synthesized and characterized successfully.

Selectivity ratio of the prepared blend PEMs is much higher than Nafion.

The proton conductivity of 7.2 × 10−3 S cm−1 was achieved by SPVdF-co-HFP/SPES10 blend membranes.

Overall membrane performance of SPVdF-co-HFP/SPES blend PEMs was superior compared to pure SPVdF-co-HFP and Nafion.

Abstract

Sulfonated poly (vinylidene fluoride-co-hexafluoropropylene) (SPVdF-co-HFP)/sulfonated poly (ether sulfone) (SPES) blend polymer electrolyte membranes (PEMs) were fabricated effectively as an alternative PEM for direct methanol fuel cell (DMFC) applications. In order to prepare PEMs with improved proton conductivity PVdF-co-HFP and PES were preferred and sulfonated using chlorosulfonic acid and sulfuric acid respectively. The presence of sulfonic acid groups were confirmed by FT-IR spectroscopy. TGA results showed that SPVdF-co-HFP/SPES blend membranes were superior than control one. Atomic force microscopy images of the blend PEMs clearly showed that the surface roughness and nodule size are increased. The influential characteristics of the PEMs, such as, water uptake, swelling ratio, ion-exchange capacity, proton conductivity, methanol crossover, selectivity ratio were characterized with respect to the control membrane. Though, the tensile strength and elongation at break slightly decreases by the addition of hydrophilic SPES, the water uptake and proton conductivity of SPVdF-co-HFP/SPES blend membranes were increased and found to be higher than that of the pure SPVdF-co-HFP. Selectivity ratio of the prepared blend PEMs were in the range of 1.709 × 104 to 2.193 × 104 S cm−3 s which is much higher than that of Nafion 117 (0.214 × 104 S cm−3s) membrane.

Graphical abstract

Keywords

  • SPVdF-co-HFP;
  • SPES;
  • Blends;
  • PEM;
  • Sulfonation;
  • Proton conductivity

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