Improved Energy Storage Density in Polymethyl Methacrylate Nanocomposites by Filling with High Aspect Ratio BaSrTiO3Nanofibers

Ceramic/polymer nanocomposites have attractive for energy storage applications in recent years. However, the discharged energy density obtained for polymer dielectrics is still restrained by the low dielectric constant (or polarization). Herein, Lead-free ferroelectric Ba
_0.6
Sr
_0.4
TiO
₃
(BST) nanofibers with a high aspect ratio are synthesized by electrospinning method and dispersed in polymethyl methacrylate (PMMA) matrix. BST/PMMA nanocomposites filling with different volume content of BST nanofibers are fabricated through a simple solution-casting method. Compared to the pristine of PMMA films, the dielectric constant of the nanocomposites increases gradually with the increase of filling content due to the interfacial polarization effect. Especially, the polarization under higher applied electric field is significantly improved, leading to an excellent energy storage density of 14.9 J/cm
³
, which is about 1.53 times than that of pristine PMMA films, accompanying with a high efficiency of 81.2%. The results indicate that the BST/PMMA nanocomposites possess an excellent energy storage properties and provide an effective approach to fabricate high energy density and high efficiency polymer dielectrics.