A study on the characterization of FEP-g-PVBSA membranes as polymer electrolytes for direct methanol fuel cells

Abstract

Poly(vinylbenzyl sulfonic acid)-grafted poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP- g-PVBSA) electrolyte membrane was prepared by radiation-induced grafting of vinylbenzyl chloride onto FEP film with subsequent sulfonation processes. An energy dispersive X-ray analysis was used to observe the cross-sectional distribution behaviors of the hydrophilic sulfonic acid groups and hydrophobic fluorine groups. The characteristics of an ion-exchange capacity (IEC), water and methanol uptake, methanol permeability, and proton conductivity as a function of the degree of grafting were studied. The IECs and water uptakes of membranes with different degrees of grafting (36 to 102%) were measured in the range of 0.8 to 1.62 meq g−1 and 10 to 30%, respectively. The proton conductivity was higher than that of a Nafion 212 membrane (6.1 E−02 S cm−1), when the degree of grafting reached 60%. The methanol permeability and uptake of the FEP- g-PVBSA membrane was significantly lower than that of the Nafion 212 membrane, and even the degree of grafting reached 102%.

Characterization of Quaternary-Ammonium-Based Ionogel Membranes for Application in Proton Exchange Membrane Fuel Cells

“…Figure 8 shows that the commercial membrane Nafion 212, used as reference, presented an average water absorption value of 11.92%, which is similar to those reported elsewhere [30,34]. The membranes formed by the [N 8,8,8,1 + ][Cl − ] ionic liquid with different IL/PVC proportions showed positive water uptake after being submerged for 24 h, resulting in average water uptake values of 5.25%, 4.06% and 4.62% for membranes M1, M2 and M3, respectively.…”

“…The results obtained for the ionogel membranes tested are presented in Table 5. It could be concluded that the commercial Nafion 212 membrane exhibits the highest value overall, with an IEC average value of 0.865 mmol/g, similar to those reported in other papers [30,31]. On the other hand, IEC values for all ionogel membranes are much lower than those achieved by Nafion 212.…”

Radiation-Grafted Membranes for Polymer Electrolyte Fuel Cells: Current Trends and Future Directions

“…Methanol permeability lower than that of Nafion 212 was also recorded. The membrane also exhibited a 1-fold lower methanol crossover (2.5 × 10 –7 cm 2 s –1 ) than Nafion 212 (5.3 × 10 –7 cm 2 s –1 ) . Similar membranes based on PFA films with favorable IEC and proton conductivity have also been reported .…”

“…The membrane also exhibited a 1-fold lower methanol crossover (2.5 × 10 −7 cm 2 s −1 ) than Nafion 212 (5.3 × 10 −7 cm 2 s −1 ). 145 Similar membranes based on PFA films with favorable IEC and proton conductivity have also been reported. 146 These membranes showed 1.2 times lower methanol crossover (2.2 × 10 −7 cm 2 s −1 ) than Nafion 212 (5.3 × 10 −7 cm 2 s −1 ).…”

Highly cross-linked poly(styrene sulfonic acid)-grafted poly(tetrafluoroethylene-co-perfluoropropyl vinyl ether) membranes with various thicknesses and their application to direct methanol fuel cell

“…In addition, styrene and vinylbenzyl chloride are widely used as a grafting monomers during the radiolytic preparation of FC membranes with proton or hydroxyl exchange groups. [4][5][6][7][8][9][10][11] Among the FC membranes prepared through a radiation grafting method, poly(styrene sulfonic acid) (PSSA)grafted fluoropolymer membranes have been extensively investigated because they show high performance as an FC membrane, for example, higher proton conductivity and lower methanol permeability. Furthermore, the radiation grafting of styrene onto a fluoropolymer film and subsequent sulfonation can be easily accomplished.…”