Preparation and improved energy storage capability of nanocomposites utilizing ultrathin 2D HfO2@TiO2 nanosheets

Abstract

Polymer-based dielectrics play an important role in electrostatic capacitor by their high energy density ([Formula: see text]) and flexibility. Herein, we designed a simple high [Formula: see text] polymer-based dielectrics by controlling the morphology and surface modification of inorganic fillers. To decrease the difference in dielectric properties between fillers and matrix of the nanocomposites, HfO2 acting as the buffer layer with high insulation and appropriate permittivity coated onto the surface of TiO2 nanosheets (TiO2 Ns) to form a core–shell structure. The introduction of HfO2@TiO2 nanosheets (HfO2@TiO2 Ns) makes the nanocomposite with higher dielectric permittivity and lower dielectric loss than poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) matrix. In addition, the HfO2@TiO2 Ns can establish an efficient barrier to limit the space charge conduction, hamper the growing electric trees, and the HfO2 layer with high insulation could hinder the mobility of charge carriers. The breakdown strength ([Formula: see text]) of nanocomposite is superior to that of polymer matrix. A small addition of 3[Formula: see text]wt.% HfO2@TiO2 Ns into P(VDF-HFP) matrix can raise the [Formula: see text] to 480.7[Formula: see text]MV/m and present a maximum discharged [Formula: see text] of 13.9[Formula: see text]J/cm3. This work demonstrates that it is an effective strategy to improve the [Formula: see text] via designing the structure and surface state of inorganic filler simultaneously.