Structural and performance investigation of hydroxylated carbon nanotube/expanded graphite/ carboxylated poly(ether ether ketone) composite bipolar plates for PEMFC

Graphite composite bipolar plates (BPs) exhibit exceptional electrical conductivity, corrosion resistance, and manufacturability, making them prime candidates for meeting DOE mass production standards. This study develops enhanced composite BPs by creating continuous hydroxylated multi-walled carbon nanotube networks on graphite substrates via chemical vapor deposition (CVD), subsequently incorporating carboxylated polyetheretherketone resin. The composite BPs achieved optimal performance with a 15-min carboxylation treatment, exhibiting a through-plane electrical conductivity of 224.9 S/cm and a flexural strength of 57.4 MPa. Compared to samples without carboxylation or hydroxylated MWCNTs, the corrosion resistance also improved, with the lowest corrosion current density recorded at 0.63 μA/cm 2 . However, excessive carboxylation time led to resin accumulation, resulting in degradation of the BPs’ properties. • Compared to commercial MWCNTs, CVD-synthesized MWCNTs exhibit superior dispersion. • Hydroxylated MWCNTs networks are constructed to enhance conductivity and strength. • Hydrogen bonds and π-π interactions boost resin-graphite interfacial adhesion. • The composite bipolar plate shows enhancement of conductivity, strength, and corrosion resistance. • The synergistic interaction between hydroxylated MWCNTs and carboxylated resin enhances interfacial compatibility.