Five-Layer Gradient Structures for Improved Energy Storage Performances on the Basis of Sandwich Framework

Abstract High energy storage performances in multilayer nanocomposites are crucial for the advancement of modern electronic and power systems. However, the large dielectric contrast between adjacent layers leads to an uneven electric field distribution, which hampers the potential for further increasing their energy storage performances. Herein, five-layer gradient-structured nanocomposites were designed and fabricated based on previous sandwich framework by introducing transition layers between the outmost insulation layer and the inner polarization layer. Meanwhile, the volume fraction of the polarization layer maintains the same in the two frameworks to minimize adverse effects on polarizations. Experimental and simulation results show that the transition layer is able to effectively reduce dielectric contrast that alleviates electric field distortion and increases two extra interlayer interfaces to prolong breakdown paths, leading to an improved Eb. In addition, Ni(OH)₂ nanosheets could further hinder the breakdown path to suppress leakage current and prevent premature breakdown. As a result, the optimal nanocomposite with x=60 achieves an energy density of 25.9 J/cm³ at 663.6 MV/m, with an efficiency of 80%. This approach provides a promising design for advanced dielectric nanocomposites.