Effect of surface wettability of polymer composite bipolar plates on polymer electrolyte membrane fuel cell performances

The effects of fluoropolymer based additive at different additive/binder and additive/filler ratios on surface wettability, conductivity and mechanical properties of polymer composite bipolar plates are investigated in this study. Fuel cell performance tests are performed at different feed flow rates by using composite bipolar plates containing organic based hydrophobic and inorganic based hydrophilic additives to investigate the effect of surface wettability properties on polymer electrolyte membrane fuel cell (PEMFC) performance. The conductivity of the composite materials decreases with the increase in additive/filler ratios, due to a decrease in the amount of conductive filler in the composite structure, whereas conductivity increases with the increase in additive/binder ratios due to a decrease in the amount of nonconductive binder. The surface hydrophobicity gets stronger with increasing fluoropolymer/filler and fluoropolymer/binder ratio amounts, related to the hydrophobic properties of both filler and fluoropolymer. In all feed flow rates, at low current densities, the single cells exhibit almost the same performance. At intermediate and high current densities, polymer composite without any additives shows higher performance than the bipolar plates containing organic or inorganic based additives. Current and power densities show maxima at the bipolar plate contact angle of 80°. ► The surface wettability of bipolar plate changes the fuel cell performance. ► The effects of additive on polymer composite bipolar plates are investigated. ► The current and power densities show maxima at a 80° contact angle.