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.