Development of PEFC Membrane Electrode Assemblies for Iron-Doped Metal Organic Framework Catalysts

Abstract

Polymer electrolyte fuel cells (PEFCs) have been identified as one of the most promising technologies for future electric vehicles by using clean H2 with much improved energy conversion efficiency, long range, and rapid refueling. However, due to the large amount of platinum group metal (PGM) catalyst used in their electrodes, their prohibitively high cost hinders broad commercialization of PEFCs for transportation. Therefore, there is a critical need to develop low cost, high-performance PGM-free cathode catalysts that have the potential to dramatically transform the economics of PEFC commercialization by reducing catalyst costs by one to two orders of magnitude. However, before PGM-free cathodes become viable, several technical challenges associated with PGM-free cathodes must be addressed, including insufficient activity and stability of the catalysts, and serious water flooding and large transport losses in the electrodes. Overcoming those barriers and ultimately meeting the challenging automotive PEFC performance targets requires comprehensive research and development effort on new PGM-free cathodes. In this work, we use a newly developed approach to synthesize PGM-free catalysts for Fe-doped metal-organic framework (MOF) precursors that yield atomically-dispersed FeN4-type active sites. These catalysts exhibit high activity and improved stability at typical fuel cell operating voltages. This presentation will focus on the development of membrane electrode assemblies with cathodes prepared from this catalyst. Specific areas that will be covered are water management in thick PGM-free cathodes, ionomer integration, and cathode fabrication. The implementation of these new materials and electrode designs is supported by a suite of advanced experimental and simulation tools that identify performance and durability bottlenecks, devise solutions, and establish rational material design and future synthesis targets. This material is based upon work supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under the Fuel Cell Technologies Office (FCTO) under Award Number DE-EE0008076. The authors gratefully acknowledge research support from the Electrocatalysis Consortium (ElectroCat), established as part of the Energy Materials Network under the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Fuel Cell Technologies Office, under Contract Number DE-EE0008076.