Polyimides Crosslinked by Aromatic Molecules and Nanocomposites for High Temperature Capacitive Energy Storage

TL;DR

This paper develops polyimide nanocomposites with enhanced high-temperature dielectric performance by combining crosslinking and nanocomposites, significantly improving energy density and thermal stability for electronic power systems.

Contribution

It introduces a novel combined strategy of crosslinking and compositing to improve high-temperature dielectric performance of polyimides, supported by theoretical and experimental validation.

Findings

Achieved ultra high discharge energy density of 5.45 J/cm3.

Suppressed charge transport via charge-trapping effects.

Enhanced thermal conductivity prevents thermal breakdown.

Abstract

High temperature polymer-based dielectric capacitors are crucial for application in electronic power systems. However, the storage performance of conventional dielectrics polymer dramatically deteriorates due to the thermal breakdown under concurrent high temperatures and electric fields, and there are hardly reports on the causes of thermal breakdown from the aspects of the high temperature conduction loss and Joule heat dissipation. Herein, a combined strategy of crosslinking and compositing for polyimide-based nanocomposites is proposed, which minimizes the thermal breakdown by significantly inhibiting the high-temperature conduction loss and enhancing the high thermal conductivity. Furthermore, the rationale of the strategy was theoretically and experimentally verified from multiple perspectives. The charge-trapping effect is directly observed and quantitatively probed by Kelvin probe force microscopy with nano level resolution, indicating that the crosslinking network introduces local deep traps and effectively suppresses the charge transport. The thermal conductivity of the nanocomposites inhibits the high temperature thermal breakdown, which is confirmed by phase field simulations. Consequently, the optimized nanocomposites possess an ultra high discharge energy density(Ud) of 5.45 J/cm3 and 3.54 J/cm3 with a charge discharge efficiency, respectively, which outperforms the reported polyimide based dielectric nanocomposites. This work provides a scalable direction for high temperature polymer based capacitors with excellent performance.