The development of fuel cell systems that can operate at the scales and power densities required for vehicle powertrains requires linking the understanding of ion transport, gas-exchange, electrochemical and catalytic action at the cell level to the fuel cell stack response in the context of the power demands of the vehicle. This calls for a combined approach integrating input from low-level physics and thermodynamic and electrochemical system modeling to address FC stack level challenges, such as how alternate cooling or humidity profiles will impact stack power and longevity and how time-dependent stack temperature and relative humidity will modulate heat production, cell impedance and losses, as well as durability/degradation of the membrane and catalyst structures.
Key research challenges are to develop proton exchange membrane fuel cells (PEMFCs) solutions that radically reduce the use or entirely remove the use of scarce noble metals, as well as to develop novel PEMFCs that can substitute perfluorinated polymers, like Nafion, which are costly to produce and difficult to recycle. A correlated aspect is the need for finding non-volatile proton conducting electrolytes alternative to acidic water, able to operate at intermediate temperatures (80 – 200 °C) and thus enable the use of cheaper and more abundant catalysts.
