Carbon/Ceramic Composite Nanofillers Derived From Solid Carburizing for Enhancing High‐Temperature Insulation Properties of Polymer Dielectrics

ABSTRACT

High‐temperature dielectric polymers are attracting increasing attention for applications in extreme environments. However, the leakage current density increases exponentially owing to the intensive migration of charge carriers under high thermal electric fields, which severely degrades the insulation properties of polymer dielectrics. In this work, a solid carburizing strategy is proposed to in situ grow carbon nanodots throughout Al ₂ O ₃ /BaTiO ₃ (AO/BT) ceramic nanofibers, constructing unique C/AO/BT composite nanofillers. In this design, carbon nanodots with Coulomb blockade effect act as deep traps to capture charges. Simultaneously, the reverse electric field between carbon nanodots and ceramic nanofibers significantly reduces carrier mobility. At an ultralow filler loading of 0.1 wt.%, the leakage current density of the nanocomposite is significantly reduced, yielding a high breakdown strength of 783 kV mm ⁻¹ at 200°C, a 76.7% improvement compared with pure PEI (443 kV mm ⁻¹ ). This work provides a novel avenue for the design of dielectric nanofillers for polymer dielectrics under extreme conditions.