Self-healing sulfonated poly(ether ether ketone)/polyvinyl alcohol membrane reinforced with sulfonated silica for direct methanol fuel cell

Nafion, the predominant choice for polymer electrolyte membranes (PEMs) in direct methanol fuel cells (DMFCs), excels in proton conductivity but is plagued by elevated methanol permeability and sustained performance degradation. To address these issues, this study aims to synthesize a self-healable composite membrane composed of sulfonated poly (ether ether ketone), polyvinyl alcohol, and sulfonated silica (S/PVA/S-SiO2). The composite membrane with 3 wt% S-SiO2 demonstrates the highest proton conductivity, thanks to its improved water absorption and increased proton transfer sites. Compared to pure SPEEK, the composite membrane has a 20% lower methanol permeability. With its enhanced selectivity, the S/PVA/S-SiO2 membrane produces a power density of 3.64 mW cm-2 at 26.67 mA cm-2. Furthermore, by virtue of reversible hydrogen bonding, the composite membrane shows exceptional self-healing capabilities, restoring its methanol-blocking function by 83.6%. These results highlight that the S/PVA/S-SiO2 membrane holds promise for DMFC applications.