Development of novel proton exchange membranes based on cross-linked polyvinyl alcohol (PVA)/5-sulfosalicylic acid (SSCA) for fuel cell applications

Abstract

The proton-conducting and methanol permeation behaviors of polymeric electrolyte membranes (PEMs), as well as the expensive nature of direct methanol fuel cell (DMFC) components, pose major concerns in DMFC performance and commercialization. As a result, this research aimed to develop low-cost polyelectrolyte membranes based on cross-linked poly(vinyl alcohol)/5-sulfosalicylic acid dehydrate (PVA/SSCA) composite. Chemical cross-linkers and modifiers offer the essential chemical and mechanical stability of the developed membranes for usage as polyelectrolyte membranes (PEMs). The manufactured composite proton exchange membranes provide several benefits, including significant thermal, chemical, and mechanical stability. The results revealed that extending the SSCA molar concentration increased IEC outcomes of the synthesized membranes, reaching an elevated level of (3.31 meq g−1) compared to (0.91 meq g−1) for the Nafion 117 membrane. The proton conductivity of a composite membrane (102 μm thick) measured by impedance spectroscopy was relatively (0.078 S cm−1) and found comparable to other PVA-based composite membranes reported in the literature. Other key parameters, such as methanol permeability, were measured for constructed composite proton exchange membranes (2.52 × 10–7 cm2 s−1), which were much lower than Nafion 117 (3.39 × 10–6 cm2 s−1). The Fourier transform infrared (FT-IR), Raman scattering spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, elemental analysis, and thermal gravimetric analysis (TGA) were among the techniques used to characterize the synthesized membranes. These characterizations confirm the structural interaction between the membrane components’ crystalline nature, and no signs of phase separation or cracks were found; surface morphology and good membrane homogeneity, elemental analysis, and the membranes’ thermal stability (up to 290 °C). The membranes were also mechanically characterized using a universal testing machine (UTM), which revealed good mechanical stability. The findings demonstrate that a low-cost proton exchange membrane could potentially be synthesized for DMFC applications.