MWCNT-infused polyaniline composite–based bipolar plates for proton exchange membrane fuel cells fabricated via 3D printing

This study investigates twin screw extruded multi-walled carbon nanotube (MWCNT)–infused polyaniline (PANI) composite–based bipolar plates (BPPs) for proton exchange membrane fuel cells (PEMFCs) fabricated via fused deposition modelling (FDM). The 3D-printed composite plates with varying MWCNT proportions (5–30 wt%) were subjected to extensive characterization, including morphological study, thermal, mechanical, electrochemical corrosion, and electrical characteristics analysis. The plates with 25 wt% MWCNT (MWCNT₂₅-PANI₇₅) outperformed the US Department of Energy (US DoE) objectives with their high mechanical strengths exceeding 40 MPa and high thermal conductivity of 20.29 W/mK at 80 °C. Corrosion analysis showed that MWCNT₂₅-PANI₇₅ substantially improved corrosion resistance with a corrosion potential (E_corr) of − 152.60 mV, a corrosion current density (I_corr) of 0.19 µA/cm², and a protection efficiency (P.E.) of 97.29%. However, the MWCNT₂₅-PANI₇₅ plate is deficient in electrical properties, with an in-plane conductivity exhibited at 80.15 S/cm, which falls short of the DoE objective of 100 S/cm, demonstrating the difficulties of combining conductivity optimization with other factors. In a single-cell PEMFC system, MWCNT₂₅-PANI₇₅ achieved power densities of 533.91 mW/cm², demonstrating its practicability. Further research is called for to enhance conductivity through covalent functionalization of MWCNTs, aiming to meet the US DoE targets and improve overall efficiency.