Enhancing energy density of dielectric polymer nanocomposites at ultralow filler loadings

Dielectric polymer nanocomposites have been extensively studied to achieve high-energy-density capacitors. However, their energy density (Ud) usually improves at the expense of transparence, light weight, and processibility of polymer matrices because of high nanofiller loadings. Herein, polydopamine-modified titanoniobate nanosheets ([email protected]_nss) were prepared as fillers. Their high relative permittivity (εr) contributes to increasing εr. Their large aspect ratio facilitates to improve the mechanical properties and distort the electrical treeing paths. Moreover, they are negatively charged and can electrostatically block energetic electrons. Thus, εr and breakdown strength of the polymer nanocomposites simultaneously enhance at ultralow filler loadings, leading to significantly enhanced Ud. The 0.2 wt% [email protected]_nss/PVDF/PMMA nanocomposites exhibit a maximum Ud of 11.5 J/cm3, which is 2.1 and 1.5 times that of pristine PVDF and PVDF/PMMA blend, respectively. This work presents a facile strategy that hardly compromises the advantages of polymer matrices to obtain high-Ud polymer nanocomposites at ultralow filler loadings.