A Modified Polyetherimide Film Exhibiting Greatly Suppressed Conduction for High-temperature Dielectric Energy Storage

Polymer dielectrics are key materials for capacitive energy storage in electrical and electronic systems owning to their ultra-high power density and high breakdown strength. However, the dramatically increased electrical conduction leads to poor energy storage performance under high electric fields, especially at elevated temperatures. Here we introduce structural defects into Polyetherimide (PEI) to modify the high-temperature dielectric properties. The polarization and conduction properties are investigated to reveal the effect of the structural defect. The modified PEI exhibits largely improved charge-discharge efficiency at elevated temperatures due to the suppressed electrical conduction, e.g., 91 % under ~400 MV/m at 200°C. The modification of PEI through a high-throughput facile process exhibited an enormous potential in capacitive energy storage under harsh conditions. The strategy demonstrated here unveils an unexplored space for modifying established polymers by introducing local structural defects.