Utilizing Ink Composition to Tune Bulk-Electrode Gas Transport, Performance, and Operational Robustness for a Fe-N-C Catalyst in Polymer Electrolyte Fuel Cell

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

Research output: Contribution to journalArticlepeer-review

62 Scopus Citations

Abstract

With lower site density and turnover frequency, platinum group metal (PGM)-free catalysts based electrodes are often greater than 50 μm 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.

Original languageAmerican English
Article number104943
Number of pages13
JournalNano Energy
Volume75
DOIs
StatePublished - Sep 2020

Bibliographical note

Publisher Copyright:
© 2020 Elsevier Ltd

NREL Publication Number

  • NREL/JA-5900-76818

Keywords

  • Ink composition
  • Ionic resistance
  • Ionomer distribution
  • Mass transport resistance
  • Nano-CT
  • PGM-Free catalyst

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