Antiferroelectric nano-heterostructures filler for improving energy storage performance of PVDF-based composite films

•The nano-heterostructures antiferroelectric PLSZST@Al2O3 fillers are obtained.•The PLSZST@Al2O3 can reduce the remnant electric displacement and leakage current.•Finite element simulation reveals Al2O3 layer can improve the breakdown strength.•High discharged energy density of 18.2 J/cm3 and efficiency of 70 % are achieved. Incorporating high permittivity inorganic ferroelectric in polymer dielectrics is the most prevalent and straightforward approach to improve their energy storage capacity, which has an extensive application prospect in power electronic circuits owing to their higher power density. However, the discharged energy density attained with these materials are mainly restrained by the high remnant electric displacement of ferroelectric and the large discrepancy in permittivity between inorganic and organic substance. Herein, we proposed a novel antiferroelectric (Pb0.875La0.05Sr0.05)(Zr0.595Sn0.4Ti0.005)O3@Al2O3 (PLSZST@AO) nano-heterostructure as fillers to fabricate nanocomposite films, wherein the Al2O3 layer with wide band gap and dielectric constant close to that of the PVDF matrix was encapsulated onto the antiferroelectric nanoparticle PLSZST to alleviate the discrepancy in permittivity and enhance the breakdown strength. Especially, the experimental results and computational simulations confirmed that the presence of Al2O3 layer is capable of effectively enhancing the electric displacement and breakdown strength, while reducing the remnant displacement and impeding the formation of electrical trees. As a result, the nanocomposite films exhibited an impressive discharged energy density of 18.2 J/cm3 along with a remarkably enhanced energy storage efficiency of 70 % near the high electrical breakdown strength of 594.7 MV/m when the fillers content was 3 wt%, which was far surpassed the pristine PVDF (Ud = 5.34 J/cm3 and η = 51.8 %). Together with its excellent mechanical strength, the monolayer film was verified to be an outstanding performance dielectric material, outperforming the current PVDF-based composite dielectrics for high-power energy storage capacitors. This work allowed for more versatility in designing and manufacturing flexibility nanocomposite films, which can contribute to improving their performance and practicality.