Polymer dielectrics intercalated with a non-contiguous granular nanolayer for high-temperature pulsed energy storage

Abstract

Polymer dielectrics suffer from significant degradation in energy density and charge–discharge efficiency at high temperatures, and incorporating inorganic nanofillers into polymer is the most straightforward and effective approach to ameliorate this behavior. However, the nanofillers are prone to form aggregated state driven by surface energy and electrostatic forces, compromising high-temperature energy storage performance of dielectrics. Here, we propose a unique non-contiguous granular intercalation strategy to solve the nanofiller aggregation problem. Specifically, an intercalation consisting of non-contiguous distributed aluminum@alumina (Al@AlO_x) core–shell nanoparticles is introduced into polyetherimide (PEI) matrix via sputtering reaction. It should be noted that the non-contiguous distribution of nanoparticles within the intercalation ensures discontinuous charge transport, which prevents the formation of conductive network within the nanocomposite. Additionally, benefiting from charge trap induced by wide-bandgap AlO_x shell and Coulomb blockade effect of Al core, the charge transport is significantly suppressed. The nanocomposite achieves ultrahigh energy densities of 9.0 J cm⁻³ at 150 °C and 6.2 J cm⁻³ at 200 °C, with charge–discharge efficiencies ≥ 90 %. This work offers a promising pathway for the design of high-temperature energy storage dielectrics and holds huge potential for scalable fabrication.