Enhanced Energy Density in a Heterostructure Capacitor of Multilayered PVDF and 2D Mica Nanocomposites

The demand for energy storage devices with high energy density, power density, and higher efficiencies has motivated researchers to explore novel materials and designs beyond current limitations. Polymer-based dielectric capacitors are flexible, lightweight, self-healable, and compatible with a variety of nanofillers. Despite a plethora of studies on polymer nanocomposites with 2D nanofillers, the role of multilayered 2D nanofillers in polymer nanocomposites in the context of energy storage properties has yet to be determined. In this work, mechanically exfoliated 2D mica nanofillers were incorporated with poly(vinylidene fluoride) (PVDF) polymer to fabricate PVDF-mica-PVDF (PMP) multilayered heterostructure capacitors. A single exfoliated layer of mica with an average thickness of the flakes of 20 nm interfaced within layers of PVDF to form PMP and using two layers of mica to form PVDF/mica/PVDF/mica/PVDF (PMPMP) heterostructure capacitors. Average enhancements of 100% and 170% were measured for the dielectric constants of PMP (ε av ∼ 22.9) and PMPMP (ε av ∼ 30.8), respectively compared to that of the pristine PVDF (ε av ∼ 11.4) films measured using the same setup. The highest discharged energy density of PMP and PMPMP nanocomposite films reached 27.5 J/cm 3 ( E = 670 MV/m) and 44 J/cm 3 ( E = 570 MV/m), compared to 11.2 J/cm 3 ( E = 396 MV/m) for the pristine PVDF capacitor. This work develops a detailed understanding of the use of multilayered 2D nanofillers to develop high-capacitance and high energy density polymeric dielectric capacitors and opens avenues for developing orientation-controlled 2D nanofiller-based capacitors for use in industrial applications.