Polypropylene nanocomposite film with enhanced energy storage performance via a continuous preparation

Dielectric polymers have been extensively employed in renewable energy conversion, hybrid electric vehicle, and high voltage direct current transmission systems, owing to their excellent electrical insulation, processability, and self-healing capability. However, the challenge lies in their relatively low dielectric constant ( ε r ) and limited discharge energy density ( U e ), which hinder the advancement of integrated power modules. Despite numerous efforts aimed at enhancing U e , the fabrication of scalable dielectric film with both enhanced U e and high charge–discharge efficiency ( η ) remains a major obstacle. Herein, the polypropylene-based films with BaTiO 3 @PP-g-MAH (BTO@PP-g-MAH) core–shell nanoparticles are prepared through a continuous melt extrusion process. The resulting nanocomposite film, incorporated with 5 wt% BTO@PP-g-MAH, exhibits an impressive U e of 5.15 J cm −3 and achieves a high η of 93.2 % at 433 MV m −1 , along with excellent cycle dielectric stability. Such enhancements in ε r and U e are ascribed to the improved interfacial polarization facilitated by BaTiO 3 nanoparticles and the enhanced interface binding achieved through the PP-g-MAH shell layers. Furthermore, the enhancement of electric breakdown strength ( E b ) is comprehensively investigated based on electrical breakdown mechanism and electromechanical breakdown model. This study demonstrates a novel strategy to prepare nanocomposite dielectric films that are compatible with commercial capacitor fabrication process.