Spatially-confined self-assembly boron nitride nanosheet interlayer in polymer nanocomposites significantly enhances the Capacitive energy storage performance

High-performance electrostatic capacitors are urgently needed of advanced electronic devices. Traditional nanodielectric designs, such as polyvinylidene fluoride (PVDF)-based nanocomposites with uniformly distributed nanofillers, necessitate laborious filler interface modification and yield limited energy density (U_e) and efficiency (η). Herein, boron nitride nanosheet (BNNS) intercalated polymer nanocomposites were innovatively prepared by plasma treatment and BNNS spatially-confined self-assembly techniques. The oriented dense interlayered BNNS substantially suppresses leakage current and bolsters the breakdown strength of nanocomposite films, outperforming randomly or oriented distributed BNNS systems, thus obtaining a higher U_e of ∼24.1 J/cm³. Moreover, the relaxation loss of PVDF could be effectively mitigated by polymethyl methacrylate and trace intercalated BNNS, maintaining an ultrahigh η (76 %) at 600 MV/m and greatly enhances the energy storage performance. Significantly, this newly designed nanocomposites necessitate only traces of BNNS (0.2 wt%) without filler-surface-modification. These findings afford insight into the programming and manufacture of high-performance electrostatic capacitors.