Characterization of nanoporous catalyst layers for PEMFCs

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Fuel cells are the only existing technology capable of directly replacing the internal combustion engine currently used on automobiles. They offer comparable range, power, refueling times, performance and reliability. The main technical barrier to commercialization is their relatively high cost owing to the use of expensive platinum as an electrocatalyst in the so-called catalyst layer (CL). Designing fuel cells to use less platinum is therefore a key step in making fuel cell cost-competitive with the century old internal combustion technology. The aim of this work is to develop tools to measure the various engineering parameters necessary to design an optimized fuel cell. The main challenge when dealing with CLs is the size-scales involved. CLs are a porous layer approximately 10 microns thick, composed carbon-platinum nano-particles, agglomerated together by a network of ion conducting polymer material, interpenetrated with a porous network of 50-500 nm pores. In this project, tools will be developed that can measure or study (a) the electronic conductivity through the percolating network of carbon-platinum particles, (b) the ionic conductivity of the ionomer network, (c) the pore size distribution and connectivity of the void network and (d) the fluid permeability in the pore space. This experimental tools on this list simultaneously provide key structural and transport parameters of these nano-porous materials. The information furnished by these tests will finally allow an independent optimization of the configuration of each phase, while understanding the impact any changes in one realm have on the others.