Experimental Study on Wettability Control Method for Fuel Cell Flow Channels and Effects on Performance

Flow channel wettability has a significant influence on performance of proton exchange membrane fuel cells, since oxygen transport in flow channels is affected by aggregation patterns of liquid water. In this work, commercial scale bipolar plates with different channel wettability were manufactured with ultrafast laser and surface hydrophobic treatment technique. Then, experiments and overpotential calculations were conducted to investigate the mechanism of flow channel wettability on fuel cell performance through distribution of relaxation times analysis. Results displayed that the fuel cell with superhydrophobic channels had a gas diffusion resistance $\mathbf{8 5 \%} \sim \mathbf{1 7 6 \%}$ higher than that of the fuel cell with hydrophilic channels, resulting in a voltage drop of 60 mV. This phenomenon is attributed to differences in the ability to remove liquid water within flow channels. This research provides a valuable insight into the design of flow channels surface wettability for performance optimization of fuel cells.