Superior capacitive energy storage capability in polymer composites induced by polydopamine-coated paraelectric platelets

摘要

Dielectric nanocomposites with excellent energy storage capabilities have great potential applications in film energy storage capacitors. However, limited energy storage density (U-e) and poor efficiency (eta) of nanocomposites based on the incorporation of the high dielectric constant (epsilon(r)) fillers restrict their practical energy storage application due to low breakdown strengths (E-b) and electric displacement difference (D-max-D-rem) value. Herein, paraelectric SrTiO3 (ST) plates have been successfully synthesized through three-step molten salt process and modified by polydopamine (PDA) nanolayer. The moderate dielectric constant ST has the advantage for increasing the breakdown strength of poly(vinylidene fluoride) (PVDF)-based composites owing to the mitigation of electric field distortion. The ST@PDA platelets bring the highest D-max-D-rem (8.65 mu C/cm(2)) together with enhanced E-b (350 MV/m) to the composites on account of the strong microscopic barrier layers. Consequently, the composite film filled with optimized ST@PDA platelets content (2.5 vol%) endows the maximum U-e of 12.45 J cm(-3) at 350 MV/m, which presents the best result when compared to the neat PVDF and dielectric nanocomposites added with diverse ST morphologies including nanoparticles, nanowires, and nanofibers reported previously. This work offers an efficiency strategy utilizing high insulating paraelectric fillers with a plate structure to maximize the improvement in capacitive energy storage performance for dielectric composites.