High discharged energy density of nanocomposites filled with double layered core-shell nanoparticles by reducing space charge polarization

Polymer-based nanocomposite capacitors for energy storage with high discharged energy density and charge discharge efficiency are of great importance to modern electronic devices and electrical systems. Herein, the energy storage properties are improved by applying double-layered core-shell nanoparticles as fillers. The dopamine was adopted as the outermost layer to improve the dispersibility and compatibility between the fillers and matrix. The high resistance of SiO2 works as a barrier to limit the movement of space charge over the BaTiO3 (BT) surface when a high electric field is applied, leading to an enhancement of breakdown strength as well as a decreased space charge polarization, so that an enhancement of discharged energy density and charge-discharge efficiency are achieved. The SiO2@BT/P(VDF-CTFE) also shows weaker frequency dependence, indicating the reduction of space charge polarization. A possible mechanism of reduced space charge polarization was proposed to explain the effects of SiO2. This work demonstrates that constructing a core-shell structure with high resistance is an effective way to improve the energy properties of nanocomposite capacitors.