Constructing three-dimensional conductive network in composite bipolar plates by sacrificial materials for improvement of proton exchange membrane fuel cell performance

The poor conductivity of traditional polymer-based composite bipolar plates (BP) greatly hinders its wide application in proton exchange membrane fuel cell (PEMFC). Three-dimensional conductive network in composite BP can significantly improve its performance. In this work, we propose a simple strategy to prepare an epoxy resin-based composite BP by sacrificial materials, forming a three-dimensional graphite structure (3D-graphite). Specifically, graphite and NH4HCO3 are mixed and pressed at room temperature, and heated at 90 °C to obtain 3D-graphite skeleton. Then, the 3D-graphite skeleton is impregnated by epoxy resin to obtain 3D-graphite/epoxy composites. The construction of 3D-graphite conductive network can greatly improve the electrical conductivity of composite BP. The highest in-plane conductivity is 212.64 S/cm, and area specific resistance is 4.50 mΩ cm2. The thermal conductivity can reach 16.01 W/mK, superior to the randomly distributed graphite/epoxy composite BP. Compared with the traditional mixed graphite/epoxy composite BP, 3D-graphite/epoxy composite BP can significantly improve the performance of PEMFC and its maximum power density (853.42 mW/cm2) is increased by 317.52%. In addition, 3D-graphite/epoxy composite BP has good corrosion resistance and hydrophobicity. This work develops a new paradigm for preparing highly performance polymer-based composite bipolar plates for PEMFC.