Enhanced polypropylene dielectric properties and energy storage with advanced multilayer structures

Abstract

In this paper, PBZ membranes with a PP/BZ sandwich structure were fabricated by incorporating ZnO nanoparticles into bacterial cellulose (BC) to form a functional BZ layer, effectively overcoming the inherent limitations of nanoparticle doping and significantly enhancing the energy storage capacity and high-temperature resistance of polypropylene (PP). The results revealed that the optimal performance was achieved with a ZnO content of 2 wt%. At this concentration, the conductivity decreased by 97.5, 98.9, and 99.6% at 25, 85, and 125 °C, respectively, while the breakdown strength increased by 50.6 kV/mm, 59.7, and 92.0 kV/mm, compared to PP. Additionally, the energy density exhibited an increase of 56.5–106.9% across various temperature ranges. The electrostatic potential and energy level distribution analyses indicated that the unique mesh structure and physical properties of BC effectively restricted the free movement of electrons within the material, reducing leakage current and enhancing the high temperature resistance of the PBZ film, while also preventing undesirable phenomena such as nanoparticle agglomeration.