Excellent energy storage properties achieved in PVDF-based composites by designing the lamellar-structured fillers

Polymer-based dielectrics are widely utilized due to the high power density, fast discharging-charging speed and broad operating temperature range. However, suffering from the inherent low energy density, the practical application is restricted. Herein, a novel structure design of lamellar-structured MgO and BiFeO₃/MgO (BFO/MgO) fillers is proposed and a series of PVDF-based composites are fabricated. The breakdown strength is significantly improved due to the large heterojunction electric field produced by BFO and MgO. Meanwhile, the large polarization contributes to a high energy storage performance. A high energy density of 9.93 J cm⁻³ at 409.6 kV mm⁻¹ with energy efficiency of 66% is achieved in 0.9 wt% BFO/MgO-PVDF/PMMA composites. Compared with previous literatures, high energy density is obtained in a relatively low electric field in this work at such trace filling content, which is quite suitable for the long-term electric field application. This work establishes a facile and effective approach for developing the flexible dielectric capacitors with high energy storage capability.