Flexible Cellulose/BaTiO₃ Nanocomposites with High Energy Density for Film Dielectric Capacitor

Regenerated cellulose/BaTiO3 nanocomposite films were fabricated by incorporation of BaTiO3 nanoparticle (BTNP) or BaTiO3 nanofiber (BTNF) in regenerated cellulose (RC) via simple blending in aqueous NaOH/urea solution. The results showed that a proper addition of BTNP or BTNF could improve the dielectric constant, breakdown strength, energy density of RC and reduce the dielectric loss simultaneously. Meanwhile, RC-BTNF composites exhibited better dielectric and mechanical properties than RC-BTNP. Especially, the RC-2BTNF composite film with 2 vol % BTNF exhibited an ultrahigh discharged energy density of 13.14 J/cm3 at a breakdown strength of 370 MV/m. Moreover, the discharged energy density of 9.45 J/cm3 at 300 MV/m of RC-2BTNF is the highest discharged energy density of reported polymer-based dielectric films at 300 MV/m (closed to actual electric field strength when film capacitors work). Therefore, these flexible cellulose-based dielectric materials are promising in the field of novel high-performance film dielectric capacitor.