Effect of methanol absorption on properties of polymer composite bipolar plates for direct methanol fuel cells

The effect of the methanol absorption on thermal, mechanical and electrical properties of highly-filled graphite polymer composite plates destined for direct methanol fuel cells was investigated. Poly (vinylidene fluoride) (PVDF), Poly (phenylene sulphide) (PPS) and Poly (propylene Glycol) (PPG) compounds were considered in this study. It was shown that the absorbed amount of methanol for PVDF compound increased linearly with the square root of time as in Fickian diffusion. The methanol uptake in the saturation stage reached the value 2% after 1500 h methanol exposure. A significant change of the thermal conductivity as well as the flexural strength was reported for PVDF compound after methanol exposure, while the electrical conductivity was not altered. Additionally PPS compound exhibited a long term resistance to methanol exposure and met to a great extent the requirements defined by the US Department of Energy on the thermal and electrical conductivity. The PPS compound is a potential candidate to be used for applications as bipolar plates in direct methanol fuel cells.

► We examine the effect of the methanol absorption on properties of bipolar plates. ► The profile of the absorbed amount for PVDF increases as in Fickian diffusion. ► The thermal conductivity decreases after methanol exposure for PVDF composite. ► PPS compound exhibited a long term resistance to methanol exposure. ► Electrical conductivity is not affected by the methanol exposure for all compounds.