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 (Ue) and efficiency (eta). 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 Ue 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 eta (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 highperformance electrostatic capacitors.