High Energy Storage Under the Regulation of Polymer Phase Structure

Dielectric nanocomposites have garnered significant interest owing to their potential applications in energy storage. However, achieving high energy density (U_e) and charge/discharge efficiency (η) remains a challenge in their fabrication. In this paper, core-shell structured BaTiO₃@Polyvinylpyrrolidone (BT@PVP) nanoparticles are prepared, and incorporated into a semi-crystalline polyvinylidene fluoride (PVDF) matrix. The BT@PVP/PVDF nanocomposite film loaded with 5 vol.% BT@PVP nanoparticles show a maximum U_e of 18.39 J cm^-3 at 458 MV m^-1, which is almost 4 and 9 times greater than those of BT/PVDF (5.14 J cm^-3 at 303 MV m^-1) and biaxially oriented polypropylene (BOPP) (2 J cm^-3 at 640 MV m^-1), respectively. Notably, the highest charge/discharge efficiency of 79.80% has been achieved so far for ferroelectric inorganic-filled PVDF composites. The reason why there are such excellent performances is mainly because of the interface coupling of inorganic-organic nanocomposite film and PVDF β phase transition with coating and extrusion of PVP molecules and large polarization of BT respectively. This research introduces a convenient and effective approach to designing high-performance dielectric polymer nanocomposites.