Bio-inspired PEI/BNNS composite film via hydrogen bond self-assembly for efficiently enhancing high-temperature dielectric energy storage

Polymer-based film capacitors are in high demand for modern electronic and electrical applications, but it is still challengeable to optimize their high-temperature energy storage capability. Herein, inspired by the regular alignment of fish scales, polyetherimide/BN nanosheets (PEI/BNNS) films with similar morphology were designed via hydrogen bond self-assembly process. The results indicated that the BNNS inorganic layer played important roles on suppressing carrier transport and reducing conduction loss, resulting in simultaneous improvements on dielectric and breakdown properties as well as energy storage performances. At room temperature, the highest energy density (U_e) of PEI/BNNS samples (PEI-BN4) achieved to 8.50 J cm⁻³ with charge/discharge efficiency (η) of 90.2 %, which increased by 77.1 % compared to the U_e of neat PEI. At 200 °C, PEI-BN4 also exhibited the highest U_e of 4.46 J cm⁻³ with η of 91.3 %, which was 94.8 % higher than neat PEI film (U_e = 2.29 J cm⁻³ with the η of 87.8 %). To the best of our knowledge, the energy storage performances of PEI-BN4 were better than most of currently reported high-temperature PEI-based dielectric films. The current work proposes a novel surface engineering strategy to design high-performance polymer composite film, and promote the applications of new generation of high-temperature resistant electronic devices.