Regulating high-temperature energy storage of crosslinked polyetherimides through functional crosslinking agent

With the rapid development of advanced electronic equipment, it is urgent to develop polymer dielectrics with excellent high-temperature capacitance. The sharp increase in conduction loss at high temperatures is the bottleneck that restricts the improvement of energy storage performance. Crosslinking has been proven to be an effective strategy for suppressing conduction loss. However, there is little research on how to select crosslinkers to construct the optimal crosslinking network. Here, a crosslinker with a unique spatial structure and low ionization energy is selected based on computational simulations to construct crosslinking networks in polyetherimide. The weakly conjugated structure suppresses charge transfer, and the charge trapping effect inhibits carrier transport, thus synergistically reducing conduction loss at high temperatures. Consequently, the crosslinked polyetherimide achieves a discharged energy density of 5.06 J cm–3, a charge-discharge efficiency of over 90%, and a charge-discharge cycle stability of 50,000 cycles at 150 °C. This work proposes a multi-effect synergistic strategy, providing new insights for the design of high-performance crosslinked polymer materials for high-temperature applications.