Abstract
In this work, we are exploring electrically-conductive polymer composites as an alternative to the traditional metal alloys commonly used for fuel cell bipolar plates. Polymer composites can reduce both the weight and cost of the bipolar plate, while still providing sufficient electrical properties. The main objective of this research is to model and injection mold polymer composites that will meet the United States Department of Energy technical target for bipolar plate electrical conductivity (> 100 S/cm). A micromechanical model was developed to predict conductivity based upon direction in the material, fiber alignment, fiber length and diameter, fiber concentration, and fiber conductivity. The conductivity predictions of this model were then compared to injection molded samples. For these samples, conductive fillers (carbon fiber and carbon nanotubes) were added to nylon at weight percentages ranging from 0 to 50%, and conductivity was measured experimentally using a four-point probe method. The analytical and experimental results show good correlation over this range of filler weight percentages. Conductivities greater than 250 S/cm were achieved, exceeding the DOE technical target. Ultimately, the combined modeling and experimental results presented here demonstrate the potential for using polymer composite bipolar plates in fuel cells.