Enhancing energy storage property of polypropylene-based sandwich composites with surface-modified nonzero dimensional nanomaterials

Polypropylene (PP) is a classical organic material for dielectric capacitor, exhibiting typical linear charge–discharge characteristics. However, its low energy density fails to meet the operating requirements of high-power and energy storage systems. In this study, techniques such as spray-coating, lamination hot-pressing, melt blending, and in situ melt-drawing are employed to fabricate PP-based sandwich-structured composite dielectrics. The outer layers consist of BN nanosheets (BNNSs)/PP composite, while the middle layer comprises Ba 0.7 Sr 0.3 TiO 3 @Polydopamine (BST@PDA)/PP. The introduction of BNNSs with a wide bandgap improves the breakdown strength of composites. BST@PDA increases the overall polarization of the composites and alleviates the local electric field concentration caused by hetero-interfacial field distortion. When the filling concentration of BNNSs is 0.10 wt% and that of BST@PDA nanowires is 3 wt%, the composite demonstrates a high dielectric constant and low dielectric loss. Additionally, the sandwich-structured composite, exhibiting a high charge–discharge efficiency of 97.80%, presents enhanced breakdown strength ( E b ~ 453 MV/m) and increased energy storage density ( U e ~ 5.67 J/cm 3 ), which are 39.38% and 189.29% higher than neat PP (325 MV/m, 1.96 J/cm 3 ), respectively. This study offers a viable and efficient approach to augment the energy storage density of PP-based dielectrics. Graphical