Significantly enhanced high-temperature energy storage capacity for polyetherimide-based nanocomposites via energy level modulation and electrostatic crosslinking

Abstract

In the field of electrostatic energy storage, polymers exhibit notable advantages, including high breakdown strength (Eb) and fast charge/discharge rates. However, at elevated temperatures, their discharge energy density (Ud) decreases due to reduced Eb and increased electrical conductivity losses. We herein integrate fluoro-functionalized polyimide (PFI) shell-modified Al2O3 nanoparticles (PFI@Al2O3) with polyetherimide (PEI) to form a trap-rich electrostatic crosslinked network. By energy level modulation and electrostatic crosslinking, the PFI layer enables to capture charges and acts as crosslinking sites, while the wide-bandgap Al2O3 introduces energy barriers that inhibit charge injection and migration. This sophisticated dual-interface design enhances Eb and facilitates dual capture of electrons and holes, thus effectively reducing leakage current and conduction losses. Surprisingly, the composites prepared using this method exhibit an energy density of 7.24 J/cm³ at 150 °C, with a charging-discharging efficiency of 83.58 %. Moreover, it maintains stability even after 105 extended charge-discharge cycles under harsh conditions (200 kV/mm and 150 °C). This work lays a solid foundation for electrostatic energy storage at elevated temperature.