Ultrahigh breakdown strength and energy density of polymer nanocomposite containing surface insulated BCZT@BN nanofibers

Abstract Novel surface insulated 0.5(Ba0.7Ca0.3)TiO3-0.5Ba(Zr0.2Ti0.8)O3 (BCZT) nanofibers adhered with boron nitride nanosheets (BNNSs), named as BCZT@BN, is used as fillers in polyvinylidene fluoride (PVDF)-based nanocomposites. Double layered film which comprises high breakdown strength (Eb) layer of PVDF/0.8 wt% BNNSs (PBN0.8) and high dielectric constant (er) layer of PVDF/0.4 wt% BNNSs/zwt% BCZT@BN (PBN0.4BCZT@BNz) is employed. The Eb is largely increased from 380 MV m−1 of pristine PVDF film to 730 MV m−1 of PVDF nanocomposite fed with 0.8 wt% BNNSs, and a high discharge energy density (Udis) of 17.9 J cm−3 is achieved at the same time. Furthermore, after introducing 1.6 wt% BCZT@BN in PBN0.8-PBN0.4BCZT@BN1.6 nanocomposites, the er reaches up to 10.7, which is substantially improved by 119% over that of PBN0.8 nanocomposite (9.1). Thus, the incorporation of BCZT@BN NFs endows the PBN0.8-PBN0.4BCZT@BN1.6 nanocomposite with an impressive energy storage density (Ue) of 24.3 J cm−3, which is 3.57 times of pristine PVDF. Finite element simulation analysis reveals that BNNSs adhered on the surface of BCZT NFs exhibit a prominent effect in local electric field elimination and leakage current density dispersion. The strategy provides an innovative approach to enhance the energy storage performance of polymer-based nanocomposites.