Soft-Rigid Liquid Metal-SiC Hybrid Fillers Enable Superior Nonlinear Conductivity and Electric Field Regulation of Composite Dielectrics.

Abstract

Nonlinear dielectrics with superior electric field regulation capabilities are essential for advanced power equipment. However, traditional nonlinear dielectric materials depend on an electrical percolation mechanism, requiring high concentrations of nonlinear conductive filler that degrade insulation and mechanical properties. Herein, we propose a synergistic strategy using a hybrid filler of soft liquid metal and rigid silicon carbide particles (LM-SiCp) to develop insulating nonlinear composite dielectrics. The unique LM-SiCp structure enables a favorable network of potential barriers at low fields and steep exponential current growth at high fields, yielding an excellent "low onset, high gain" nonlinear behavior. The resulting composites exhibit an impressive nonlinear coefficient of ∼7.55 and a markedly reduced threshold field strength from 4.81 to 3.41 kV/mm. It also achieves improved toughness (2.29 MJ/m³), thermal conductivity (0.36 W/mK), high breakdown strength (∼33.4 kV/mm), and low dielectric loss (<0.03), which ensure the stable performance of the composite dielectric under practical engineering conditions. This strategy offers a novel design concept for high-performance composite dielectrics capable of effective electric field modulation in power equipment.