Optimizing high-temperature capacitive energy storage performance by constructing crosslinked structure in self-crosslinkable polyetherimides

Crosslinking is a proven method for effectively improving the high-temperature energy storage performance of polymer dielectrics . In this work, the relationship between crosslinked structure and energy storage performance was demonstrated by crosslinked polyetherimide films with various degree of crosslinking. Specifically, the maximum weight average molecular weight (M w ) of soluble parts and proper gel content favors the formation of an optimal crosslinked structure with an optimal energy density (∼3.6 J/cm 3 ) and charge–discharge efficiency (≥ 95%) at 150 °C. Furthermore, the energy storage performance of the crosslinked films obtained by the longtime treatment under relatively low temperatures is equivalent to that obtained by the short-time treatment under relatively high temperatures. This work provides a reference model for designing high-temperature crosslinked polymer dielectrics.