Achieving exceptional high-temperature capacitance energy storage in polyimide through aromatic structure-based electron induced effects

Polyimide, endowed with high thermal resistance due to its aromatic structure, is considered a potential candidate for high-temperature polymer dielectrics. However, the strong electron delocalization in the aromatic structure causes significant leakage current during high-temperature electron transport, impairing energy storage performance. This contradictory relationship presents a bottleneck in enhancing the high-temperature energy storage performance of PI. In this work, inspired by fish migration influenced by vortices, we propose inducing electron displacement through fluorine-modified aromatic structures, constructing an internal electric field in PI to affect electron transport. This approach cleverly resolves the conflict between thermal resistance and current loss caused by the aromatic main chain in PI, achieving a synergistic enhancement of thermal resistance and high-temperature energy storage performance. Experimental results show significant improvements in both the high heat-resistant quality and high-temperature energy storage performance of PI. The glass transition temperature increased from 257.32 °C to 264.07 °C, and the leakage current density decreased from 7.1 × 10 –7 A/cm 2 to 2.8 × 10 –8 A/cm². Simultaneously, with a charge-discharge efficiency of approximately 90 %, the discharge energy density increased from 0.36 J/cm 3 to 5.22 J/cm 3 , an improvement of 1345.98 %. This strategy validates the potential of aromatic structures as the main chain for high-temperature energy storage polymers.