Enhanced dielectric properties and energy density of flexible KTa_0.2Nb_0.8O₃-BaTiO₃/P(VDF-TrFE-CTFE) nanocomposite

In this work, KTa_0.2Nb_0.8O₃–BaTiO₃ (KTN–BT) hybrid nanoparticles were synthesized via a facile one-pot hydrothermal method. Flexible nanocomposite films comprised of poly (vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) P(VDF-TrFE-CTFE) matrix and KTN–BT hybrid fillers of different molar ratio were prepared by solution-casting. It is revealed that the introduction of BT to the KTN causes decreased grain size and homogenous morphology, improving the dielectric constant, breakdown strengthen and energy density of nanocomposite films. Typically, the nanocomposite film containing 40 vol% KTN–BT possesses a dielectric constant of 322 at 100 Hz, which is 8.7 times than that of pure polymer. Also, nanocomposite film with < 10 vol% of filler could achieve high breakdown strength of over 300 MV m⁻¹. The energy density of the film containing 2 vol% KTN–BT filler is 61.4% higher than that of pure P(VDF-TrFE-CTFE) polymer. (7.1 J cm⁻³ compared to 4.4 J cm⁻³.) In addition, the nanocomposites also displayed good flexibility and kept excellent dielectric properties after bending and folding. All the improved performance enables these composites to meet the requirements of many flexible electronic devices and energy storage devices.