Electro-mechanical properties of the carbon fabric composites with fibers exposed on the surface

Abstract

The carbon/epoxy composite is an ideal substitute for the brittle graphite bipolar plate of the proton exchange membrane fuel cell (PEMFC) because of its high mechanical property and productivity. However, composite bipolar plate suffered from high electrical contact resistance due to the resin-rich area formed on the surface. In order to decrease the contact resistance, "soft layer method", which could expose bare carbon fibers on the composite surface, was developed. The soft layer method significantly improved the electrical properties of the unidirectional continuous carbon fiber/epoxy composite at the expense of slight degradation of the mechanical properties. In this work, the soft layer method was improved further to develop the carbon fabric/epoxy composite bipolar plate for the PEMFC. Compared to the conventional composite bipolar plates, the developed composite bipolar plates showed superior electrical properties as well as significant increase in the mechanical properties and gas tightness.