Stable Energy Storage Performance at High-Temperature of PESU-based Dielectric Composite Regulated by SiO2 and BNNSs

Polymer dielectric capacitors are essential components for energy storage in modern electronic devices. They offer several advantages, including excellent voltage resistance, easy processing, and great energy storage density (U). However, with high thermal and electric fields, the more conductivity losses of polymer dielectric materials can be generated and aggregated, and the discharge energy density (Ue) and charging-discharging efficiency (η) of dielectric capacitor are usually significantly lower than that at room temperature. Here, the state-of-the-art composite is proposed, in which the SiO2 filler with excellent insulation strength is introduced into the middle composite layer, and the composite introduced wide band-gap boron nitride nanosheets (BNNSs) is used as the outer composite layer to inhibit carrier migration and reduce leakage current density of composite. The experimental results illustrate that the Ue of 1BP/1SP/1BP dielectric composite reaches about 9.37 J/cm3, and the η is around 82.0 % under the electric field of 540 kV/mm at 80 °C. Significantly, the η of multilayer 1BP/1SP/1BP composite remained >95.0 % after 50,000 cycles, indicating that this multilayer composite has good cycle stability and excellent reliability under a high-temperature. It presents a practical approach to enhance the energy storage performance of dielectric polymer at high-temperature environment.