Multifunctional Exfoliated Graphene Nanoplatelet/ HDPE and /PPS Nanocomposite PEM Fuel Cell Bipolar Plates

X. Jiang, L.T. Drzal
Michigan State University, US

Keywords: graphene, composites, fuel cell

Summary:

An investigation was conducted to determine the potential of using multifunctional exfoliated graphene nanoplatelets (GnP) as the reinforcement in fabricating polymer/GnP nanocomposites as compression molded bipolar plates for polymer electrolyte membrane (PEM) fuel cells. High density polyethylene (HDPE)/GnP and polyphenylene sulfide (PPS)/GnP nanocomposites were investigated in this study. The mechanical properties, crystallization behavior, thermal stability, thermal conductivity, and electrical conductivity of the resulting HDPE/GnP nanocomposites were evaluated as a function of GnP concentration to 50 weight percent. It was found that HDPE/GnP nanocomposites exhibit equivalent flexural modulus and strength to HDPE composites filled with other reinforcements but have superior impact strength. GnP was also found to be a good nucleating agent at low loadings which can significantly increase crystallization temperature and crystallinity of HDPE. The thermal stability and thermal conductivity of HDPE/GnP nanocomposites was significantly enhanced. To reduce the percolation threshold and enhance the electrical conductivity of HDPE/GnP nanocomposites, solid state ball milling (SSBM) and solid state shear pulverization (SSSP) were applied to this system. A low molecular weight polyethylene sizing applied to the GnP greatly enhanced dispersion resulting in significant improvement in the HDPE/GnP electrical and mechanical properties. To evaluate the potential of using GnP nanocomposites as bipolar plates in PEM fuel cells, HDPE/GnP bipolar plates for low‐temperature applications and polyphenylene sulfide (PPS)/GNP bipolar plates for high‐temperature were compression molded and evaluated. Because of the excellent combination of mechanical, structural, thermal and electrical properties of GnP nanocomposites, bipolar plates made from them can meet or exceed the DOE targets.