Composite catalyst layer, electrode and passive mixing flow field for compressionless fuel cells

摘要

The application relates to improvements to the composition and architecture of compressionless fuel cells. The invention includes a hybrid or composite catalyst layer which includes a blend of catalyst particles, such as platinum on carbon, and fibers, such as graphite fibers. The invention also relates to a castable gas diffusion layer (GDL) which is both porous and electrically conductive. The GDL is formed from conductive metal flakes, such as gold and silver, carbon particles and binder to hold the flakes and particles together to form a porous foam microstructure. The invention further relates to a modified flow field for flowing fluid to or from the catalyst layer of a fuel cell. The flow field comprises at least one primary channel having a longitudinal axis and a plurality of secondary channels extending transversely from the primary channel at an angle relative to the longitudinal axis. The secondary channels induce the fluid flow path to rotate to thereby passively increase the probability of contact and mixing between the fluid and the catalyst layer. This in turn improves the delivery of reactants to the catalyst layer and the removal of reaction products from the catalyst layer. The catalyst layer, GDL and flow field may be synergistically combined to improve the efficiency and performance of compressionless micro fuel cells.