Enhancement of high temperature capacitive performance of sulfone-containing polyimide by suppressing carrier transport

With the increasing demand for safe operation in harsh environments, polymer dielectric capacitors with high energy density (Ue) and charge-discharge efficiency (η) operating at high temperatures are urgently needed. In this work, the sulfone group-containing polyimide (SO2PI) film with optimal imidization degree is prepared by regulating the kinetics of imidization reaction. The functional groups obtained by partial imidization enable polyimide to achieve excellent energy storage performance, and it is found that the presence of sulfone groups is beneficial for the further improvement of η. The optimal SO2PI film achieves a Ue of 2.40 J cm−3 at 400 MV m−1 and 150 °C, while it maintains a high η of 92%. Moreover, its preparation process without any additional modification steps matches commercial production equipment, indicating a simple and effective strategy for fabrication of a high-performance dielectric film. Thus, this work exhibits great potential in the field of high temperature energy storage.