Flexible dielectric nanocomposites with simultaneously large discharge energy density and high energy efficiency utilizing (Pb,La)(Zr,Sn,Ti)O3 antiferroelectric nanoparticles as fillers

Abstract

Dielectric nanocomposites composed of a polymer matrix with high electric breakdown strength and inorganic ferroelectric nanofillers with large maximum electric displacement (D_max) have recently attracted much attention due to their high power density, superior flexibility, and good fatigue endurance. However, their discharge energy density and energy efficiency are limited because of the high remnant displacement (D_r) and small D_max − D_r values of the ferroelectric fillers. Compared with ferroelectrics, antiferroelectrics exhibit much lower D_r (near zero) and far larger D_max − D_r values, and thus if they are used as the fillers of the dielectric composite, a larger discharge energy density and higher energy efficiency may be obtained simultaneously. Based on this, in this work, Pb_0.97La_0.02(Zr_0.50Sn_0.45Ti_0.05)O₃ (PLZST) antiferroelectric nanoparticles (∼200 nm in diameter) coated with a dense and robust dopamine layer are prepared in order to develop dopamine-modified PLZST filler/poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) polymer nanocomposites with superior energy storage properties. The experimental results indicate that optimizing the filler content leads to a small D_r (0.61 μC cm⁻²), large D_max − D_r value (6.14 μC cm⁻²), and high electric breakdown strength (3136 kV cm⁻¹), as a result of which, the PLZST/P(VDF-HFP) nanocomposites filled with 5 wt% dopamine-modified PLZST nanoparticles simultaneously exhibit a large discharge energy density of 9.39 J cm⁻³ and high energy efficiency of 82%. These energy storage properties are superior to those of most ferroelectric filler (including nanowires and nanofibers prepared by complicated methods)/polymer nanocomposites with a single-layer structure. Our work not only proves that, antiferroelectric nanoparticles are excellent fillers that can be comparable to, or even better than, ferroelectric nanowires and nanofibers prepared by very complicated methods, for energy-storage inorganic/polymer dielectric composites, but also provides a convenient and effective way to prepare and design flexible dielectric capacitors with superior energy storage capacity.