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DOE OSTI · 1756762

Utilizing ink composition to tune bulk-electrode gas transport, performance, and operational robustness for a Fe-N-C catalyst in polymer electrolyte fuel cell

Osmieri, Luigi·Wang, Guanxiong·Cetinbas, Firat C.·Khandavalli, Sunilkumar·Park, Jaehyung·Medina, Samantha·Mauger, Scott A.·Ulsh, Michael·Pylypenko, Svitlana·Myers, Deborah J.·Neyerlin, K. C.
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Abstract

With lower site density and turnover frequency, platinum group metal (PGM)-free catalysts based electrodes are often greater than 50 mu m thick in order to increase performance across the fuel cell operating range. Consequently, PGM-free electrodes have an additional bulk electrode transport resistance beyond the local or aggregate level transport in thin platinum-based electrodes. In parallel to the development of more active and durable PGM-free catalysts, advancements in understanding the interplay between PGM-free electrode fabrication, bulk-electrode transport, proton conductivity and performance are needed. Here, the relationship between ionic and gas phase transport through the electrode thickness is modified by adjusting electrocatalyst and ionomer flocculation/interaction at the ink level. The influence of the ink composition (water/n-propanol content) is examined via various in-situ electrochemical and ex-situ characterization techniques and the resulting electrode structure/performance relationship contrasted with electrode performance robustness across a range of relative humidity (RH). For the electrocatalyst examined here, a water-rich (82 wt% H2O) ink formulation was favorable for operation at high RH due to improved molecular diffusion through larger electrode pores. In contrast, the improved interactions between ionomer and electrocatalyst enabled a more robust electrode and higher performance during low RH operation for the 50 wt% H2O content ink.

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08 HYDROGEN30 DIRECT ENERGY CONVERSIONPGM-free catalystink compositionionic resistanceionomer distributionmass transport resistancenano-CT

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Osmieri, Luigi, Wang, Guanxiong, Cetinbas, Firat C., Khandavalli, Sunilkumar, Park, Jaehyung, Medina, Samantha, Mauger, Scott A., Ulsh, Michael, Pylypenko, Svitlana, Myers, Deborah J., Neyerlin, K. C.. 2020-09-01. Utilizing ink composition to tune bulk-electrode gas transport, performance, and operational robustness for a Fe-N-C catalyst in polymer electrolyte fuel cell. https://doi.org/10.1016/j.nanoen.2020.104943

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