With the development of renewable energy sources, dielectric capacitors play a pivotal role in energy conversion devices. However, the current commercial dielectric film materials, due to their low energy density, struggle to meet the requirements for device miniaturization and modularization. In recent years, significant improvements in the discharged energy density (Ue) of composite films have been achieved through the incorporation of various ceramic fillers and the design of topological layer structures. Nonetheless, the energy storage efficiency (eta) of these composite films remains low due to inevitable energy loss at the ceramic-polymer micro-interface, limiting their large-scale commercial application. To address this issue, our work introduces a novel strategy: by designing an asymmetric multilayer structure, multiple macro-interfaces are introduced to replace some of the micro-interfaces within composite films, thereby reducing energy loss and enhancing eta. Specifically, we propose an innovative asymmetric four-layer structure composite film, which achieves a stellar Ue value of 34.54 J center dot cm-3 and an unprecedented eta value of 95.82 % at 660 MV center dot m- 1. This design adequately reduces the adverse impact of internal micro-interfaces on the energy storage characteristics of the composite films, achieving the optimal integrated energy storage performance so far.
