Currently, the application of polymer dielectric capacitors is largely limited by their low energy storage density. Herein, novel sandwich-structured composite films with simultaneously enhanced energy storage density and efficiency are fabricated, which combine outer layers of inorganic nanosheets Ni(OH)₂/poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) with high permittivity and intermediate layer of polycarbonate (PC) with high breakdown strength. The trilayer film with only 1 vol% Ni(OH)₂ exhibits an excellent energy storage density of 7.322 J/cm³ accompanied with a high efficiency of 72.1 % at 605 kV/mm, which are 120 % and 113 % of pure P(VDF-HFP). Furthermore, hindrance effect of micro-interfaces and macroscopical-interfaces on electrical trees is well revealed through finite element simulation. These excellent characteristics of composite films suggest that this design strategy is effective to realize concurrent high energy density and efficiency.

目前，聚合物介电电容器的应用在很大程度上受到其低能量存储密度的限制。_{在此，制备了同时增强能量存储密度和效率的新型夹层结构复合薄膜，该薄膜将无机纳米片Ni(OH) 2} /聚(偏二氟乙烯-六氟丙烯)(P(VDF-HFP))外层与高介电常数和具有高击穿强度的聚碳酸酯（PC）中间层。_{仅含有 1 vol% Ni(OH) 2}的三层薄膜表现出优异的储能密度，为 7.322 J/cm ³，同时在 605 kV/mm 下效率高达 72.1 %，分别是纯 P( 的 120 % 和 113 %)。 VDF-HFP）。此外，通过有限元模拟很好地揭示了微观界面和宏观界面对电树的阻碍效应。复合薄膜的这些优异特性表明这种设计策略可以有效实现同时实现高能量密度和效率。