Durable High Efficiency Membrane and Electrode Assemblies for Heavy Duty Fuel Cell Vehicles

Heavy-duty vehicles (HDVs) operate under more stringent conditions than light-duty cars, i.e., longer driving distances, more idling, higher voltage operation, increased thermal stress, and more exposure to impurities. Successful MEAs for HDVs should have >65% efficiency and >25,000 hours of durability while limiting the total platinum group metal (PGM) loading to 0.3 mg/cm2. However, it has been extremely challenging to reach these targets at such low PGM loading using existing catalysts and supports. The first goal of this Phase II project is to scale up the robust Pt NP ORR catalysts on a highly efficient PGM-free active support that was developed and validated in Phase I, and integrate it with HOPI to develop large scale high-performance MEAs with the desired durability, able to generate high-power for HDVs. The second goal is to scale up the MEA size via large scale electrode coating methods for commercialization. In Phase I, our team successfully synthesized, characterized and tested multiple high performance 20 and 40 wt. % Pt and PtCo catalysts supported on the unique Mn-N-C. We found that when integrated with Giner’s high oxygen permeability ionomer, the 40wt% Pt/Mn-N-C catalyst showed remarkable performance and durability, meeting all the project milestones by retaining >1.2 A/cm2 at 0.7 V after 150,000 AST cycles between 0.6-0.9V; which was not the case for the catalyst when commercial ionomers were used. The Phase II project will focus on scaling up the 40 wt% Pt/Mn-N-C catalyst to at least 50 g per batch, whereby the scaled-up catalyst performance will match the performance of the small-scale version of catalyst from Phase I. Various large scale coating methods will be evaluated including roll to roll slot die coating, screen printing and ultrasonic spray coating, to identify the method that yields the electrode structures with the best in-situ performance and durability. The integrated Giner MEA innovation targets the ever-growing market for fuel cell vehicles. The successfully scaled-up Pt/Mn-N-C along with the high oxygen permeability ionomer, prepared using the most promising large scale manufacturing method, will be used to prepare 100 cm2 MEAs, which will be delivered to Plug Power, Nikola and Hyzon, for in-situ heavy duty performance and durability evaluation, to support rapid fuel cell market penetration.