Sammendrag
The gas diffusion layer (GDL) is a multifunctional part of a fuel cell governing reactant and product transport in opposing directions, thermal and electrical conductivity as well as mechanical stability. Its design and production are cumbersome and, for now, obtainable architectures are random networks with uncontrollable transport pathways. According to simulations, an optimized "designer GDL" architecture may lead to immediate benefits in conductivity and permeability by several orders of magnitude.1 This could result in an increase of the achievable current density and a reduction in transport losses. To realize transport optimized architectures, a fabrication method is required that can convert architectures with computer defined properties directly into physical models.2 Here we present our latest results on the fabrication of "designer GDLs" with high-resolution stereolithography of dimensionally stable photopolymers with high aromatic content. These polymers have the potential to be converted to amorphous carbon at predictable dimensional shrinkage retaining their CAD defined geometry. Particularly, we present the high-throughput fabrication of polyimide and SU-8 formulations. We present process parameters, tolerances achievable and show initial results on the carbonization of these formulations as well as absolute dimensions and tolerances obtainable. Our research may lead to a new toolbox for studying and fabricating the next generation of porous membranes for Polymer Electrolyte Membrane Fuel Cells (PEMFCs) and likely a variety of other electrochemical devices requiring effective transport characteristics.
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