Preparation of hybrid ceramic/PVC composites showing both high dielectric constant and breakdown strength ascribed to interfacial effect between V2C MXene and Cu2O

Abstract

High dielectric constant and breakdown strength of composite dielectrics are key for high energy density in capacitors. However, high dielectric constant is frequently accompanied by rather low breakdown strength. To obtain high dielectric constant and breakdown strength, in this work, polymer-based ternary composites bearing V2C MXene-Cu2O hybrid filler have been prepared. First, V2C and V2C-Cu2O fillers were synthesized. Then, binary polymer/V2C and ternary polymer/V2C-Cu2O composite films were fabricated. Via measurements, significantly optimized electric traits were realized in ternary composites compared with binary ones. In ternary system, higher dielectric constant was attributed to high-polarity V2C/Cu2O interface-phase, notably reduced dielectric loss low polymer/V2C interface leakage conductance, and greatly improved breakdown strength low total leakage current. Finally, V2C/Cu2O interfacial effect was disclosed using density functional theory (DFT) calculations. Electronic migration and stable bonding at interface were rationalized. Ternary composite with 7 wt% filler showed a high dielectric constant of ~55 and low dielectric loss of ~0.085 at 100 Hz as well as high breakdown strength of ~332 MV m−1. In novelty, V2C/Cu2O interface-phase containing quantum-sized high-polarity micro-regions has been proposed to contribute to high dielectric constant of ternary system. This research might enable preparation of advanced composite dielectric materials.