Construction of proton transport channels and performance Modulation of phosphotungstic acid hybrid proton exchange membranes for direct methanol fuel cell

Serving as the central part of a direct-methanol fuel cell (DMFC), a proton exchange membrane (PEM) is used to conduct protons, isolate electrons and fuel, and ensure the proper operation of the battery. The novel hybrid proton exchange membrane (PEM) proposed in the present work is comprised of polyethyleneimine (PEI) and polyvinyl alcohol (PVA) doped with phosphotungstic acid (PWA). PEI provides numerous locations for PWA anchoring and allows for the creation of efficient and continuous proton transport channels over long distances. PEI can be cross-linked with PVA through Glutaraldehyde (GA), which not only suppresses the disadvantage of PVA as a proton exchange membrane that tends to swell after water absorption and leads to deformation, but also the hydrogen-bonded network structure formed after cross-linking is conducive to proton hopping conduction, which synergistically improves the proton conduction rate of PEMs. A good compromise between the amount of PWA doping and the electrochemical properties of PEMs can result in optimal performance. Compared to other reported PEMs that use hetero-poly acids or other inorganic acids, PVA/PEI-PWA2 PEM exhibits superior overall properties. The highest proton conductivity of PVA/PEI-PWA2 is 124.3 mS cm-1 at 80 degrees C, the highest peak power density can reach 109.8 mW cm-2 (301.8 mA cm-2) at 60 degrees C, and the methanol barrier performance and selective permeability are 4.95 x 10-7 cm2 s- 1 and 12.32 x 104 S s cm-3, respectively.