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

Abstract 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.