Ultra-high Capacitive Energy Density in Heterostructure of Polymer and Stratified 2D Layered Nanofiller Composites*

Developing a thin polymer based dielectric film with improved dielectric constant and breakdown voltage is one of the emerging fields of interest to create next generation high power density energy-storage device. Here, we willresent remarkably enhanced dielectric constant and energy density of a polymer nanocomposite, PVDF with incorporated an exfoliated layered 2D dielectric crystals Mica or h-BN in a stratified heterostructure stacking geometry. The dielectric constant of this structure shows ~100% enhancement over the pristine PVDF based polymer, achieved using an ultra-low loading (~1 vol%) of 2D Mica nanofillers. A dramatic enhancement of breakdown voltage is also measured in these 2D-Mica or h-BN interfaced stratified heterostructure assembly (1000-1200 V/µm) compared to the pristine polymer heterostructure film (558-700 V/µm). We observed an energy density as high as 75 J/cm³ from the 2D-Mica interfaced polymer heterostructure construct, which is the highest among the observed energy density of the polymer-nanocomposite based dielectrics. Our computational study using density function theory supports our experimental finding. This work will provide to achieve thin film based large-scale fabrication of high-density energy storage devices using low-cost polymer nanocomposites for myriads of potential applications for flexible electronics.