Bio-Inspired Fluoro-polydopamine Meets Barium Titanate Nanowires: A Perfect Combination to Enhance Energy Storage Capability of Polymer Nanocomposites.

Rapid evolution of energy storage devices expedites the development of high-energy-density materials with excellent flexibility and easy processing. The search for such materials has triggered the development of high-dielectric-constant (high-k) polymer nanocomposites. However, the enhancement of k usually suffers from sharp reduction of breakdown strength, which is detrimental to substantial increase of energy storage capability. Herein, the combination of bio-inspired fluoro-polydopamine functionalized BaTiO3 nanowires (NWs) and a fluoropolymer matrix offers a new thought to prepare polymer nanocomposites. The elaborate functionalization of BaTiO3 NWs with fluoro-polydopamine has guaranteed both the increase of k and the maintenance of breakdown strength, resulting in significantly enhanced energy storage capability. The nanocomposite with 5 vol % functionalized BaTiO3 NWs discharges an ultrahigh energy density of 12.87 J cm-3 at a relatively low electric field of 480 MV m-1, more than three and a half times that of biaxial-oriented polypropylene (BOPP, 3.56 J cm-3 at 600 MV m-1). This superior energy storage capability seems to rival or exceed some reported advanced nanoceramics-based materials at 500 MV m-1. This new strategy permits insights into the construction of polymer nanocomposites with high energy storage capability.