High-temperature dielectric energy storage films with self-co-assembled hot-electron blocking nanocoatings

Polymer thin films operable under concurrent electric and thermal extremes represent critical building blocks of capacitive energy storage and electrical isolator for modern power and electronic systems with ever-increasing demands for power density and payload efficiency. However, polymer dielectrics are prone to fast aging under high fields due to hot electrons injected from electrodes. Especially, performance high-heat polymers such as polyimides with high aromaticity suffer fast aging induced by non-thermalized electrons even at moderate fields due to their intrinsically low bandgap and injection barrier. Herein, a facile, low-cost, and scalable interface-engineering approach utilizing the highly ordered organic/inorganic layered nanocoatings is reported, which serve as a retrofittable solution to break this design constraint. By probing the energetic modes of transport and aging at pre-breakdown field, we demonstrate that our 2D montmorillonite (MMT) self-co-assembly nanocoatings can effectively boost the dielectric properties of substrate polyimide (PI) film by suppressing the charge injection and shifting the fast mode of hot-electron aging to a slow, ultimately thermalized process. This aging-impeding scheme imparts PI films with an exceptional endurance capability (enhanced by 100 MV/m) and a 6× improved charge-discharge efficiency at an elevated temperature of 175 °C. The nanostructured interface engineering disclosed in this work thus opens a new pathway of boosting the performance of a spectrum of high-heat polymer dielectrics already commercially available in thin gauges of films for applications in zero-emission electric aircraft and renewable energy integration.