Introducing Side Groups on the Diamine Benzene Ring of Polyetherimide to Enhance the High-Temperature Energy Storage Performance

Polyimide (PI) and its derived polymers with high glass transition temperature (Tg) have become a research hotspot in high-temperature energy storage materials in recent years. However, the exponential increase in leakage current density of the materials at 150 °C limits their application at high temperatures. Therefore, this article designed two polyetherimide (PEI) derived polymers with different side groups to solve the problem of decreased energy storage performance of the materials at high temperatures. The thermal stimulation depolarization current test (TSDC) results show that the introduction of -Cl and -CF3 groups in the material constructed deeper energy level traps and provides more trap density. Finally, PEI-CF 3 exhibits the optimum discharge energy density (Ud) of 5.5 ~J / cm3 at 150 °C when the charge-discharge efficiency (η) exceeds 90 %.