Obtaining high dielectric constant and breakdown strength in composites with asymmetric MXene filler and highly insulative PVC matrix

Utilizing percolation of symmetric MXene filler easily achieves high dielectric constant in polymer/MXene composites. However, percolation leads to low breakdown strength. In present work, we have adopted a new strategy of employing asymmetric bimetallic VTiC MXene filler to fabricate composite dielectrics with highly insulating polyvinyl chloride (PVC) matrix. VTiC filler was prepared via heat-pressing and etching. PVC/VTiC composite films with varied filler contents were prepared via solution cast. Different surface work functions of VTiC were confirmed via density functional theory (DFT) calculations. Compared with several polymer/symmetric monometallic MXene composites in our prior works, PVC/VTiC composites show simultaneously improved dielectric and breakdown properties. In later, high dielectric constant stems from cooperation of filler's asymmetry and polymer/filler interface polarization, and high breakdown strength is rooted in matrix's ultrahigh insulation. Optimized PVC/VTiC composite with 10 wt% filler possesses a high dielectric constant of ∼203, low dielectric loss of ∼0.13 at 100 Hz and high breakdown strength of ∼374 MV m−1 at direct-current field. Innovation of this work is use of asymmetric MXene filler for constructing polymer-based composite dielectrics with promising properties. This work might pave a road for large-scale preparation of advanced dielectrics for capacitors.