Highly conductive composites for fuel cell flow field plates and bipolar plates

摘要

This invention provides a fuel cell flow field plate or bipolar plate having flow channels on faces of the plate, comprising an electrically conductive polymer composite. The composite is composed of (A) at least 50% by weight of a conductive filler, comprising at least 5% by weight reinforcement fibers, expanded graphite platelets, graphitic nano-fibers, and/or carbon nano-tubes; (B) polymer matrix material at 1 to 49.9% by weight; and (C) a polymer binder at 0.1 to 10% by weight; wherein the sum of the conductive filler weight %, polymer matrix weight % and polymer binder weight % equals 100% and the bulk electrical conductivity of the flow field or bipolar plate is at least 100 S/cm. The invention also provides a continuous process for cost-effective mass production of the conductive composite-based flow field or bipolar plate.

主权项

1. A continuous, in-line roll-to-roll process for producing a fuel cell flow field plate or bipolar plate, said process comprising:
(A) continuously feeding and unwinding a sheet of porous substrate from a roller toward a desired direction, said substrate having through-thickness pores; (B) mixing and feeding a conductive filler, a thermoset binder, a thermoplastic matrix material and a carrier fluid onto said porous substrate and directing said carrier fluid to substantially flow through said pores, leaving behind a layer of a solid mixture of said filler, binder and matrix material on said substrate, wherein said binder is in an amount of at least 0.1% but less than 5% by weight of the total weights of the conductive filler, thermoset binder, and thermoplastic matrix combined; (C) moving said substrate so as to allow said solid mixture layer to go through a compaction stage; (D) heating and consolidating said solid mixture layer and generating flow channels on a surface of said solid mixture layer to form said flow field or bipolar plate; and (E) rewinding the porous substrate onto a roller.