Ultra-superior high-temperature energy storage properties in polymer nanocomposites via rational design of core–shell structured inorganic antiferroelectric fillers

Abstract

Current polymer nanocomposites for energy storage suffer from both low discharged energy density (U_e) and efficiency (η) with increasing temperature due to their large remnant electric displacement (D_r), small breakdown strength and high conduction loss at high temperature. To solve these issues, herein, polyetherimide (PEI) nanocomposites filled with core–shell structured nanoparticles, composed of a (Pb,La)(Zr,Sn,Ti)O₃ (PLZST) antiferroelectric core and an Al₂O₃ shell, are developed. The PLZST core possesses large maximum electric displacement (D_max) and low D_r in a wide temperature range, which helps refine high-temperature electric displacement–electric field loops of the nanocomposites. The utilization of the Al₂O₃ shell with dielectric constant close to that of the PEI matrix, wide band gap, and high thermal conductivity alleviates the distortion of the electric field around inorganic fillers, creates deep traps and promotes Joule heat dissipation, resulting in improved breakdown strength and suppressed conduction loss. Consequently, an ultrahigh U_e of 10.20 J cm⁻³ at 150 °C, which is a record high value for dielectric polymer composites at elevated temperature, is achieved with a large η of 83.5%, simultaneously. Finite element simulations reveal the influence of the core–shell structure on electrical tree evolution, electric field distribution and internal temperature in nanocomposites, and prove the rationality of the design strategy.