Optimizing high-temperature energy storage capability enabled by regulating interchain spacing with tailored pendant group in self-crosslinkable polyetherimide

Abstract

Excellent high-temperature energy storage dielectrics are of great significance to the development of advanced electronic devices. Polyetherimide (PEI) as a high-temperature dielectric film, demonstrates obvious decline in charge-discharge efficiency with increasing temperature due to the β-relaxation effect. In this work, the crosslinking PEI is regulated by introducing self-crosslinking phenylacetylene groups, and the β-relaxation is restricted by introducing deep traps in the resultant network, thereby reducing conduction loss. The relationship between crosslinking structure, bandgap, and energy storage performance have been investigated systematically. The optimized crosslinkable dianhydride content and an appropriate gel content contribute to the formation of the deep trapping sites in the received PEI film. The optimal film exhibits the outstanding energy storage performance, e.g. energy density of 14.6 J cm -3 with charge-discharge efficiency of 90.4% under external field of 600 MV m -1 at 150 °C. The suspension arm disrupts the long-range conjugated structure of PEI, and the weakening of bond conjugation hinders electron delocalization, which results in the reliable insulation of the crosslinking polymer with high bandgap of 3.22 eV. This strategy of inhibiting relaxation while breaking coupling in the crosslinking PEI provides fresh insight on the investigation of high-temperature polymer dielectrics for film capacitor.