Utilizing ink composition to tune bulk-electrode gas transport, performance, and operational robustness for a Fe–N–C catalyst in polymer electrolyte fuel cell
With lower site density and turnover frequency, polymer electrolyte 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. 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.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE), Hydrogen and Fuel Cell Technologies Office (EE-3F)
- DOE Contract Number:
- AC36-08GO28308; AC02- 06CH11357
- OSTI ID:
- 1660058
- Report Number(s):
- NREL/JA-5900-76818; MainId:9479; UUID:108fc15e-ebc8-4301-a4cb-c20544248d33; MainAdminID:13841
- Journal Information:
- Nano Energy, Vol. 75; ISSN 2211-2855
- Publisher:
- Elsevier
- Country of Publication:
- United States
- Language:
- English
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