Enhanced High-Temperature Energy Storage in a Polyimide Alloy via Oriented High-Bandgap P(TFE-PPVE).

Polymer dielectric films are widely used in advanced electronics, hybrid vehicles, etc., however, they encounter critical challenges, including significant thermal degradation and heightened leakage currents, which severely constrain their energy density and efficiency under high-temperature conditions. Herein, a novel strategy is proposed for constructing a polyimide (PI) alloy by incorporating high-bandgap copolymer of perfluoropropyl perfluorovinyl ether and tetrafluoroethylene (P(TFE-PPVE)) and fluorinated polyimide (FPI) as a compatibilizer. The highly oriented structural PI/FPI/P(TFE-PPVE) alloy is fabricated via knife casting, which utilized high shear forces to align the P(TFE-PPVE) blocks within the polyamide acid. Simulation results indicate that the high-bandgap P(TFE-PPVE) phase (9.72 eV) with an oriented structure in the PI matrix can effectively suppress electrical tree growth. Furthermore, deep carrier trap at the PI/P(TFE-PPVE) interface (2.98 eV) further reduces leakage current and enhances breakdown strength while minimizing conduction loss. As a result, the PI/FPI/0.25P(TFE-PPVE) alloy demonstrates remarkable dielectric stability under diverse conditions, achieving a discharge energy density of 3.75 J cm with 90% efficiency at 150 °C and 550 MV m. This straightforward blending strategy provides an effective pathway to modulate the condensed structure of all organic polymers, offering promising potential for high-performance polymer dielectrics.