Enhanced Energy Storage Properties of PP/PA11 Dielectric Composite Films With PP-g-MAH as Compatibilizer

Abstract

As an energy storage capacitor film material, polypropylene (PP) suffers from its low dielectric constant and limited energy density. To overcome the defects of pure PP, the PP-based all-organic composite films with multiple interfaces have been constructed to enhance the dielectric and energy storage properties. In this research, PA11 was used to blend with PP with polypropylene grafted maleic anhydride (PP-g-MAH) as compatibilizer. The prepared PP/PP-g-MAH/PA11 composites formed the typical “sea-island” structure and double interfaces between PP/PP-g-MAH and PP-g-MAH/PA11. The higher molecular polarity of PP-g-MAH, PA11, and interfacial polarization significantly increases the dielectric constant of the composite films. Furthermore, the formation of interface traps suppressed the migration of charge carriers, resulting in lower leakage current and higher breakdown strength of the PP/PP-g-MAH/PA11 composite films. Density functional theory (DFT) simulation further proved the confinement of space charges. Energy storage results showed the optimal PP/PP-g-MAH/PA11-2 film achieved high energy density (4.49 J/cm³) and excellent charge/discharge efficiency (97.4%), which behaved good application prospect in the field of thin film capacitors.