Impact of Hybrid Carbon Nanofillers on Nanocomposite Bipolar Plates for Proton Exchange Membrane Fuel Cells

ABSTRACT Polymer composite bipolar plates (BPs) containing conductive carbon fillers are explored in this paper to develop BPs for proton exchange membrane fuel cells (PEMFC). Although various carbon‐based fillers have been investigated, studies on hybrid systems combining carbon nanofibers (CNF) and multi‐walled carbon nanotubes (MWCNT) with epoxy and other conductive fillers remain limited. To address this gap, this work examines the effects of incorporating a synergistic blend of CNF and MWCNT along with natural flake graphite (NG) and carbon black (CB) in an epoxy matrix to fabricate nanocomposite BPs via compression molding. The composite BP with 40:46:10:4 vol.% of epoxy, NG, CB, and CNF + MWCNT blend, respectively, achieves an in‐plane electrical conductivity of 205 S cm −1 , flexural strength of 48 MPa, corrosion current density of 0.228 μA c m −2 , and thermal conductivity of 5.35 W m −1 K −1 . The composite BP with 1.0 vol.% reduced Graphene Oxide (rGO) by expense of NG attains an increased in‐plane electrical conductivity of 215 S cm −1 , flexural strength of 46 MPa, corrosion current density of 0.202 μA c m −2 , and thermal conductivity of 4.38 W m −1 K −1 . The results confirm that simultaneous CNF–MWCNT incorporation is an effective approach for developing a hybrid nanocomposite BP material for PEMFC.