Enhanced dielectric properties and energy density of polypropylene films by introducing functional interlayer

Abstract In this paper, an innovative approach was presented to enhancing the dielectric properties and energy storage capacity of polypropylene (PP) membranes by introducing a bacterial cellulose (BC) layer doped with rochelle salt (RS) nanoparticles, combining nanoparticle doping and sandwich modification technique. Optimal performance was achieved at an RS content of 5 wt%, resulting in a reduction of conductivity by 85.4%, 91.2%, and 97.3% at 25 °C, 85 °C, and 125 °C, respectively. Breakdown strength improved by 8%–21%, and energy density increased by 58%–86.2% across these temperatures compared to pure PP. The unique mesh structure of BC enhanced polarization and insulating strength while mitigating nanoparticle agglomeration. Additionally, the BC/RS layer effectively regulated charge migration, ensuring exceptional performance under high temperature conditions. This work demonstrates the potential of interfacial engineering to optimize the dielectric and energy storage properties of polymer-based materials.