Advanced PGM-free Cathode Engineering for High Power Density and Durability
Recipient Carnegie Mellon University (PI: Litster, Shawn)
Subs Prof. Gang Wu (University at Buffalo, the State University of New York), Dr. Hui Xu (Giner, Inc.), Dr. Andrew Haug (3M Company)
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 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 the proposed comprehensive research and development effort on new PGM-free cathodes. To this end, we have assembled a team including leading researchers from universities and industry with different, but complementary expertise and capabilities. We will combine three novel and promising approaches: 1. Advanced metal-organic framework (MOF)-derived M-N-C catalysts with a high activity and impressive durability approaching DOE targets, 2. Novel PGM-free specific cathode architectures and fabrication strategies capable of addressing the substantial flooding and transport resistances in thicker cathodes by introducing engineered hydrophobicity through additives and support layers, and 3. Advanced electrode ionomers with high proton conductivity for low ohmic losses across the electrode and more uniform catalyst utilization for better durability. The implementation of these new materials and electrode designs will be supported by a suite of advanced experimental and simulation tools that allows us to identify performance and durability bottlenecks, devise solutions, and establish rational material design and synthesis targets. These methods include advanced electrochemical characterization, high resolution imaging, and multi-scale modeling from the quantum-level to the full PEFC-scale. In addition, we will leverage a wide cross-section of the ElectroCat consortium’s national laboratory facilities and expertise in advancing these materials and design strategies. The industry partners on the project are well-poised to facilitate the evaluation of scaled-up synthesis and manufacturing in the United States. Ultimately, reaching automotive performance targets with PGM-free cathodes requires significant increases in power density and lifetime at the automotive rated cell voltages. Our overall project goal is to produce high power density and durable PGM-free cathodes through modeling and designing advanced electrode architectures that leverage the new MOF-derived catalyst and advanced ionomers.