Cellulose/BaTiO3 nanofiber dielectric films with enhanced energy density by interface modification with poly(dopamine)

ABSTRACT Flexible electrostatic capacitors have many potential applications in modern electric power systems. In this study, flexible cellulose-based dielectric films were prepared by compositing regenerated cellulose (RC) and one-dimensional BaTiO3 nanofiber (BTNF) via a simple and environmentally friendly process. To improve compatibility and distributional homogeneity of the fillers/matrix, BTNF was surface modified by dopamine to prepare the poly(dopamine) modified BTNF (PDA@BTNF). The obtained RC/PDA@BTNF composite films (RC-PDA@BTNF) possessed higher dielectric constant and breakdown strength than those of the RC and RC/BTNF composite films. In particular, RC/PDA@BTNF composite films with 2 vol% PDA@BTNF (RC-2PDA@BTNF) exhibited a high discharged energy density of 17.1 J/cm3 at 520 MV/m, which exceeded 40% compared with that of RC-2BTNF at 460 MV/m. Meanwhile, RC-2PDA@BTNF could continuously work for more than 10000 times with a high efficiency of 91%. Furthermore, the composite films could maintain good dielectric properties for a long time when stored in vacuum condition (under 0.3 atm). Therefore, these flexible cellulose-based dielectric materials are promising in the field of novel high-performance film dielectric capacitors.