Enhanced energy storage property of all-organic dielectrics by gradient layered design of sea-island structures

Abstract

Polymer dielectrics possessing the superiorities of easy processing and high power density are widely used in pulsed power and power electronics. However, the low energy storage density (U_e) of polymer dielectrics limits their application in the modern electronic industries. In this work, we present the sea-island structure multilayered composites based on polymethylmethacrylate (PMMA) matrix and polyvinylidene fluoride (PVDF) nanoparticles, which is constructed by the solution blending with typical solubility differences method and the layer-by-layer solution casting method. The PVDF/PMMA composite incorporated with high PVDF content is placed in the middle of the sandwich-structured composite as a non-traditional intermediate polarization layer. The PVDF/PMMA composite with low PVDF loading is placed in the outer layer to improve the insulating property of the composite. The results show that the PVDF/PMMA composites with inner and outer PVDF volume content of 30% and 10%, respectively, obtained an excellent dielectric constant value (ε_r ~ 4.35), which is 45% higher than that of PMMA (ε_r ~ 3). Meanwhile, the maximum U_e (~ 4.95 J cm⁻³) of the PVDF/PMMA composites at an electric field of 422.48 MV m⁻¹ was obtained, which is 207% higher than that of PMMA (U_e ~ 1.61 J cm⁻³). The improved energy storage capability could be attributed to the introduction of highly polarizing particles, the increased number of heterogeneous interfaces, and the multilayered construction of composite. This work provides a strategy for the preparation of advanced all-organic dielectrics with a higher discharge energy density.