Fabrication of High‐Performance Polymethyl Methacrylate/Graphite Composite Bipolar Plates Based on a Pre‐Wrapping Core‐Shell Strategy

ABSTRACT Polymer/carbon composite bipolar plates (BPPs) are promising for proton exchange membrane fuel cells (PEMFCs) owing to their corrosion resistance, lightweight characteristics, and facile manufacturability. Nevertheless, conventional composites fabricated via melt blending typically require around 80 wt% filler to attain sufficient electrical conductivity, which encounters a trade‐off with mechanical integrity. This work introduces a pre‐wrapping strategy to construct a continuously conductive network architecture with a core‐shell structure, inspired by Chinese glutinous rice balls (Chinese Tang‐yuan). This strategy involves pre‐wrapping graphite/trimethylolpropane triacrylate (TMPTA) mixtures onto polymethyl methacrylate (PMMA), where graphite/TMPTA serves as the “conductive shell” and PMMA particles as the “insulating filling”. Then the constructed “Tang‐yuan” particles are hot‐pressed into BPPs, and the graphite/TMPTA shell forms a continuously conductive network. Experimental results demonstrate that the BPP formulation containing 55 wt% graphite content achieves an in‐plane conductivity of 139 S/cm, an area specific resistance (ASR) as low as 6.38 mΩ·cm ² , and a flexural strength of 31 MPa. This design effectively decouples the conflicting requirements between electrical and mechanical performance. Microstructural analysis reveals that TMPTA effectively promoted the interconnection between graphite, forming continuous conductive pathways. Furthermore, the BPP exhibits excellent hydrophobicity and corrosion resistance, demonstrating the promising prospects for long‐term PEMFC applications.