Nanocellulose/BaTiO3 composite films with improved breakdown strength and energy density for dielectric capacitors

The limited energy storage density which is ascribed to low dielectric constant impedes the more diversified applications of polymer dielectric capacitors, and the environmental pollution problem caused by petroleum-based polymers cannot be ignored. Cellulose has the characteristics of wide source, low cost, and strong polarization generated by the hydroxy groups on the molecular chain giving it a high dielectric constant. In addition, nanocellulose has excellent mechanical properties that enable it to be fabricated into homogeneous films with high tensile strength. In this work, barium titanate nanoparticles (BTNPs) were incorporated into nanocellulose films to obtain enhanced dielectric performance. The composite film has the best comprehensive performance with BTNP content of 0.9 wt.%, resulting in a discharge energy density of 5.21 J cm −3 and charge/discharge efficiency of 77.7% at 350 MV m −1 . Consequently, nanocellulose-based dielectric materials give great promise for applications in biopolymer-based dielectric capacitors. Graphical abstract