Tuesday, July 03, 2007

US Patent 7238413 - Porous conductive film formed with carbon microfibers and carbon nanofibers


The formation of gas diffusion layers for fuel cells requires thin, flexible, strong material that is electrically conductive. This patent discloses forming such a sheet material using both carbon microfibers and carbon nanofibers. Claim 1 reads:

1. A conductive microporous sheet material comprising primary carbon fibers having a cross-sectional dimension of at least 1 micron, secondary carbon fibers in the form of carbon nanofibers and a binding agent for binding said primary and secondary fibers, wherein the binding agent constitutes less than 10 wt % of the sheet material and the binding agent is selected from the group comprising thermoplastic resins and thermosetting resins; and wherein the sheet has a tensile strength of between 0.7 and 1.3 kN/m.