Energy density and efficiency of scalable polymer nanocomposites utilizing core-shell PLZST@Al2O3 antiferroelectric fillers with dielectric gradient

Ferroelectric/polymer based dielectric nanocomposites deliver high power density, but low discharged energy density (U-e) and charge-discharge efficiency (eta), which are resulted from high remnant electrical displacement (D-r) of ferroelectric fillers and large dielectric difference between ferroelectrics and polymers, constrain their use in integrated electronic equipments. Here, we provide an effective and low-cost strategy for developing high-energy-density and high-efficiency dielectric nanocomposites by incorporating core-shell structured PLZST@Al2O3 nanoparticles (NPs) as fillers into P(VDF-HFP) polymer matrix. The introduction of PLZST antiferroelectric (AFE) cores with large maximum electrical displacement (Dmax) and small Dr can substantially increase D-max-D-r values and narrow D-E loops of dielectric nanocomposites. The addition of Al2O3 shells with wide band gap and dielectric constant near that of the P(VDF-HFP) matrix can prevent the charge injection from electrodes and cause the applied electric field evenly distribute, and thus inhibit the leakage current and increase the breakdown strength (E-b), which are confirmed by finite element simulations. Consequently, benefited from large D-max-D-r of 7.93 mu C/cm(2) and Eb of 5281.68 kV/cm, PLZST@Al2O3/P(VDF-HFP) nanocomposites with 3 wt% filler contents exhibit simultaneously a large U-e of 17.95 J/cm(3) and high eta of 75%, which outperform those of all latest NPs/polymer nanocomposites in terms of overall capacitive performances and are even higher than those achieved in polymer nanocomposites loaded with nanowires or nanofibers fabricated by complicated methods. This study exhibits a promising way to promote the industrialized fabrication of dielectric capacitors through capitalizing on the synergy of the dielectric constant gradient, wide band gap and AFE characteristics of the fillers.