Preparation and energy storage performance of transparent dielectric films with two-dimensional platelets

Polymer-based dielectric composites exhibiting high dielectric permittivity, low loss, high energy density, high charge-discharge efficiency, and easy process are critical to the development of cost-efficient and lightweight capacitors. BaTiO₃/poly (vinylidene fluoride) (BT/PVDF) composites using two-dimensional (2-D) platelets were prepared and investigated in this work. The composites were prepared by a simple combination of solution cast and quenching treatment, without multiple-layer architecture or surface chemical treatment. The dielectric properties and energy storage performance of the composite were improved significantly compared to pristine PVDF. The composite film with a very low content of BT (1 wt%) illustrates a high discharge energy density of 9.7 J/cm³ at 450 MV/m, which is 2 times of pristine PVDF and nearly 5 times than the best commercial biaxially-oriented polypropylenes. In addition, the composite films show an excellent cycle stability and fatigue endurance. Simulation further revealed the local electric field and local polarization distribution of composite. The energy performance also matches or surpasses many previous reported composites with zero-dimensional (0-D) BT particles, one-dimensional (1-D) BT nanowires, and other 2-D dielectric fillers. This study provides a solution for obtaining high energy density dielectric composites with very low filler content by a simple and easy method, which is highly desired for power systems and advanced electronics.