Development of graphite‐filled polymer blends for application in bipolar plates

Abstract

In this study, the potential of conductive polymer composites based on graphite‐filled polymer blend for achieving high‐performance polymer electrolyte membrane fuel cell (PEMFC) bipolar plates (BPs) was investigated. Maleic anhydride grafted polypropylene‐compatibilized polypropylene (PP)/epoxy blend was selected as the matrix due to its good combination of mechanical strength and ductility, and its potential to form a co‐continuous morphology, which promotes the selective distribution of the filler in one of the polymer phases and formation of high electrical performance‐CPCs. PP/epoxy/graphite composites, with varying amounts of graphite, were prepared by melt mixing followed by compression molding, and then characterized. The results obtained showed that in‐plane and through‐plane electrical conductivities increased with an increase in graphite content while the flexural strength increased with graphite content up to a maximum value of 54.36 MPa at 70 wt% graphite, and then decreased to 40.16 MPa at 80 wt% graphite. The PP/epoxy/80 wt% graphite composite has the most promising combination of properties for BP application. While the PP/epoxy/80 wt% graphite composite exhibited in‐plane and through‐plane conductivities (68.03 and 3.211 Scm−1, respectively) that are still below the targets set by the United States Department of Energy (DOE), its flexural strength and modulus (40.16 and 11.47 GPa, respectively), density (1.77 gcm−3), and water absorption (0.098%) satisfy the DOE targets.

Synergistic enrichment of electrically conductive polypropylene‐graphite composites for fuel cell bipolar plates

“…The maximum value of electrical conductivity recorded in this section was 21.7 S/cm at 84 wt.% graphite content. With an increase in the filler concentration, the interaction between the graphite microparticles has been increased, leaving behind a reduced polymer‐filler interface resulting in a significant enhancement in the electrical conductivity 32 …”

“…With an increase in the filler concentration, the interaction between the graphite microparticles has been increased, leaving behind a reduced polymer-filler interface resulting in a significant enhancement in the electrical conductivity. 32…”

Microporous Graphite Composites of Tailorable Porosity, Surface Wettability, and Water Permeability for Fuel Cell Bipolar Plates

“…All the plates exhibited a conductivity higher than 100 S cm −1 , significantly greater than the through-plane conductivities of some graphite−polymer composite plates previously reported in the literature. 21,22,27 The higher through-plane conductivity is attributed to the use of high-aspect-ratio graphite particles (cf. Figure 3b), the lower compression molding pressure (9.58 bar compared with 68.9 bar used by Huang et al 22 ) leading to a more random orientation and better interparticle contact of the conductive graphite flakes, and the higher graphite concentration in the plates of the present study (80−90 wt % compared with 64−70 wt % used in other graphite−polymer composites 21 ).…”

“…No voltage and current values could be measured due to excessive flooding of the flow channels in the SiO 2 -coated bipolar plates. Alo et al 27 reported the synthesis of graphite bipolar plates using a maleic anhydride-grafted polypropylenecompatibilized polypropylene/epoxy blend as the matrix. They found that the plate with 80 wt % graphite exhibited the optimal combination of flexural strength and electrical conductivity.…”

Comparative study of flexural and physical properties of graphite-filled immiscible polypropylene/epoxy and high-density polyethylene/epoxy blends

“…26,27 This can have significant influence on the behavior of their blend systems and cause blends of these polyolefins with the same polymer to exhibit considerably different properties. In our previous studies, 23,25,28 it was found that graphite-filled epoxy (PP/EP) and high-density polyethylene (HDPE/EP) blends (polyolefin: epoxy = 55:45) exhibited higher in-plane and through-plane electrical conductivities than several filled single polymers reported in the literature. Higher electrical performance of PP/EP and HDPE/EP composites was attributed to co-continuous structure of the blends, which favored concentration of filler in the epoxy, leading to more conducting pathways within the composites.…”