Effect of high aspect ratio additives on microstructural and mass transport properties of the microporous layer in a proton exchange membrane fuel cell

Tuning up transport properties of the microporous layer is an effective way to enhance mass transport in a proton exchange membrane fuel cell. The incorporation of non-spherical conductive additives in the conventional microporous layer can modify its pore structure. In this study, 5, 20, and 50 wt.% of two high aspect ratio additives, multiwall carbon nanotube and graphene nanoplatelet, are mixed with the acetylene -black carbon to systematically study their impact on ink and the final diffusion media properties. Using a bottom-up approach, the rheological properties of the ink are correlated to the mass transport resistance in the diffusion media. The ink with additives exhibits rheological properties of a less compact microstructure with large agglomerates. Whereas, a more compact agglomerated network is observed from the ink with pure acetylene black carbon nanoparticles. Graphene nanoplatelet has a dominating effect on the surface quality of the microporous layers due to its two-dimensional structure. The test results show that the microstructure formed by the synergy of acetylene black and additives can enhance ohmic and mass transport performance. 20 wt.% of the additive loading is found to be optimal and multiwall carbon nanotube shows the best fuel cell performance.

Automated summary

Tuning up the transport properties of the microporous layer by incorporating non-spherical conductive additives can enhance the mass transport in a proton exchange membrane fuel cell. Two high aspect ratio additives, multiwall carbon nanotube and graphene nanoplatelet, were mixed with acetylene-black carbon to study their impact on ink and diffusion media properties. It was found that 20 wt.% of the additive loading was optimal and multiwall carbon nanotube showed the best fuel cell performance.