Direct methanol fuel cell performance of Nafion®/poly(vinyl alcohol) blend membranes

In this study, the direct methanol fuel cell performance of Nafion®/poly(vinyl alcohol) (PVA) blend membranes at 5, 10, and 20 wt% PVA (annealed at 230 °C) was investigated at various methanol feed concentrations (2, 4, 8, and 16 M) and compared to the performance of Nafion® 117 at similar membrane thicknesses and fuel cell conditions. For Nafion® 117, the maximum power density decreased three-fold when the methanol feed concentration increased from 2 to 16 M. The Nafion®/PVA (5 wt% PVA) blend membrane reveals a similar trend, however the decrease in power is only 26% compared to 47% when methanol concentration is increased from 2 to 8 M. Furthermore, the maximum power density of the blend membrane (5 wt% PVA) is higher than Nafion® 117 at 2, 4, and 8 M methanol feed concentrations, while the maximum power density at 16 M is comparable between the two membranes. Specifically, at 8 M methanol, the maximum power density of the blend at 5 wt% PVA is 33% higher than Nafion® 117. Blend membranes at higher PVA concentrations are noticeably lower in performance compared to Nafion® 117. Overall, fuel cell performance trends match observed transport property (proton conductivity and methanol permeability) trends.