Percolation-Driven Electrical and Dielectric Behavior of PBS Nanocomposites with MXene/CNT/h-BN Hybrid Fillers

In this study, high-performance hybrid composites were fabricated by incorporating MXene, carbon nanotubes (CNTs), and hexagonal boron nitride (h-BN) into a poly(butylene succinate) (PBS) matrix. The synergistic interaction between two-dimensional MXene sheets, one-dimensional CNT networks, and insulating h-BN platelets enabled the formation of a controlled percolative structure with enhanced interfacial polarization and charge transport. Among all compositions, the PBS/MXene/CNT/h-BN hybrid composite (S10, total filler fraction = 0.20) exhibited the optimum multifunctional performance. As a result, the dielectric constant increased from 3.2 (pure PBS) to 110 at 1 kHz, while maintaining a dielectric loss of 0.31. The AC conductivity improved significantly, reaching 1.6 × 10−3 S/m, indicating efficient charge transport pathways. The composites exhibited a maximum energy density of 0.04868 J/cm³ with an efficiency of 85%, demonstrating improved energy storage capability. Notably, the EMI shielding effectiveness increased from 1.5 to 52 dB, with absorption-dominated shielding (96.8%), highlighting superior electromagnetic attenuation performance. Despite increased conductivity, the incorporation of h-BN preserved dielectric stability and improved breakdown strength up to 17 kV/mm. Percolation analysis confirmed a three-dimensional conductive network with a critical exponent of t = 1.9 and a percolation threshold of pc = 0.12, confirming the establishment of an interconnected conductive structure.