Surface hydroxylation of polymer-derived SiCN ceramics to improve the dielectric performance of the SiCN/PVDF composites

Abstract

Dielectric capacitors have attracted considerable attention in recent years due to their safety, environmental friendliness, high power density, and long service life. However, constrained by the limitations of dielectric materials, the energy storage density of the dielectric capacitors remains suboptimal. Therefore, the development of novel high-performance dielectric materials is imperative. In this work, surface-hydroxylated SiCN ceramics (H-SiCN) were employed as fillers, and H-SiCN/PVDF composites displaying superior dielectric attributes and considerable energy storage density were attained via a hot-pressing technique. After the surface hydroxylation of SiCN, the permittivity of the H-SiCN/PVDF composites increases slightly, the dielectric loss decreases, and the breakdown strength enhances significantly. When the volume fraction of H-SiCN is 20 vol%, the H-SiCN/PVDF composite film achieves the maximum energy storage of 12.23 J cm⁻³, which is increased by 101.2% compared to that of the SiCN/PVDF composite film. Robust hydrogen bonds are formed between the F atoms of PVDF and the hydroxyl groups on the surface of SiCN, which strengthens the interfacial combination between them and promotes polarization intensity. This work may provide reference significance for the design of high-performance dielectric materials.