Aluminum macrocycles induced superior high-temperature capacitive energy storage for polymer-based dielectrics via constructing charge trap rings†

Abstract

Electrostatic capacitors are typically necessary to operate in harsh-temperature environments to fulfill the demanding requirements of renewable energy, electrified transportations, and advanced propulsion systems. However, achieving exceptional capacitive performance in polymer dielectrics at elevated temperatures and electric fields remains a formidable challenge owing to the exponential growth of conduction loss. Herein, we propose a new class of polymer dielectric composites comprising polyetherimide (PEI) incorporated with a monodispersed aluminum macrocycle (AOC). The Al–O backbone of the AOC creates a ring, where electron-rich O atoms exhibit a strong charge scattering effect and electron-deficient Al atoms have a charge capture capability. Such a unique structure reduces both electron concentration and mobility, thereby effectively inhibiting charge transport within polymer dielectrics and significantly suppressing the high-temperature electrical conduction loss even at high electric fields. Consequently, the PEI-AOC composite exhibits the maximum discharged energy density with an efficiency above 90% of 6.57 J cm⁻³ and 4.4 J cm⁻³ at 150 °C and 200 °C, which exceed those of the original dielectric by more than ten-fold under identical conditions. This work presents a groundbreaking approach to manipulate the high-temperature capacitive performance of polymer dielectrics in practical power apparatus and electronic devices.