Enhancement of Energy Storage Performances in PMMA/PVDF Nanocomposites with Low Dielectric Bismuth Carbonate Nanosheets

Both high discharge energy density (U_d) and charge–discharge efficiency (η) for nanocomposites are crucial to the development and application of modern electronic devices. However, the large dielectric contrast and ferroelectric phase greatly limit the improvement of U_d and η of poly­(vinylidene fluoride) (PVDF)-based nanocomposites. Herein, Bi₂O₂CO₃ (simplified as BOC) nanosheets with low dielectric constant and wide bandgaps and linear poly­(methyl methacrylate) (PMMA) were filled into PVDF by solution casting to fabricate x vol % BOC/PAPF (PAPF is short for PMMA/PVDF) nanocomposites. The contributions of BOC nanosheets and linear PMMA, especially for the BOC nanosheet, have been systematically studied. Both experimental and simulation results show that BOC nanosheet and PMMA could improve the breakdown strength and reduce the dielectric loss and leakage current of nanocomposites simultaneously, realizing U_d and η improvement at the same time. As a result, the 1.0 vol % BOC/PAPF nanocomposite shows the highest energy storage performance with U_d = 13.68 J/cm³ and η = 85.72%, which is much superior to PVDF. Therefore, this study might provide a proof-of-concept for constructing nanocomposites with excellent U_d and η concurrently.