High Energy Density Performance of Polymer Nanocomposites Induced by Designed Formation of BaTiO₃@sheet-likeTiO₂ Hybrid Nanofillers

Nanocomposites incorporating inorganic nanoparticles (NPs) within ferroelectric polymeric matrices have great potential for high density energy capacitors. In this strategy, employing the nanostructures with specially designed morphology as fillers would notably improve the energy storage. However, this strategy is extremely challenging and has not been largely explored. Here, the BaTiO 3 @sheet-likeTiO 2 core–shell NPs have been successfully synthesized, and can be well-dispersed into polyvinylidene fluoride (PVDF) matrices. The nanocomposites with the volume fraction 2.5% BT@TiO 2 NPs have higher the electric displacement (6.0 μm/cm 2 ) than that of PVDF films with the 2.5 vol % BaTiO 3 (BT) NPs (5.1 μm/cm 2 ) under the same electric field of 350 kV/mm, which is mainly ascribed to the hierarchical interfacical polarization induced by the large surface area of TiO 2 sheet assembled on BT NPs in the nanocomposites. Simultaneously, the medium permittivity TiO 2 with medium ε r as a buffer layer between the BT NPs and polymer matrix could minimize the inhomogeneous electric field in the nanocomposites, which results in the enhancement of the breakdown strength (490 kV/mm with 2.5 vol % BT@TiO 2 NPs) compared to pristine PVDF. As a result of a gratifying E B and D, the energy density of the nanocomposites with 2.5 vol % BT@TiO 2 NPs reached 17.6 J/cc.