Gas diffusion nonwoven carbon paper for fuel cell with controllable contact resistance and hydrophobicity by laser engraving

초록

Gas diffusion nonwoven carbon paper (GDNCP) for proton exchange membrane fuel cell (PEMFC) is a kind of nonwoven carbon fiber/carbon matrix composite fabricated by wet-laid process and subsequent carbonization process. GDNCP is coated with a hydrophobic fluoropolymer for water management, but the electrically insulative polymer increases electrical contact resistance with other PEMFC components, bipolar plate and electrode assembly. In this study, laser engraving process was employed to control surface characteristics of GDNCP. The process made it possible to selectively decompose and lift off the thin layer of fluoropolymer along the flow path on the bipolar plate. Microstructural observation, and chemical and mechanical analysis showed that the laser engraving well lift off thin polytetrafluoroethylene (PTFE) layer with no visible damage on carbon fibers, and also that the contact resistance was significantly reduced. The laser-engraved pattern on GDNCP induced enhancement in the current density and power in PEMFC.