Achieving Excellent High-Temperature Energy Storage Performance in Aromatic Polymer Films via Multi-Scale Interface Engineering

Abstract

The increasing integration and miniaturization of power electronic devices is making it difficult for traditional polymer dielectrics to meet the demands of hightemperature operation. This creates an urgent need to develop new polymer dielectric materials that can store energy effectively at high temperatures. Although aromatic polymers such as polyimide (PI) and polyetherimide (PEI) have high glass transition temperatures, their electrical conductivity deteriorates significantly at high temperatures and their dielectric constants are relatively low. This limits improvements in high-temperature energy storage performance. To address the aforementioned bottlenecks, this study proposes a multi-scale structural co-regulation strategy, constructing a PI/PEI blend system at the molecular scale and utilizing interchain electrostatic forces to achieve a dense packing of chain segments, thereby enhancing the dielectric strength. At the nanoscale, the introduction of Ca2Nb3O10@Al2O3 nanosheets enhances the dielectric response whilst introducing deep energy level traps to suppress carrier migration. At the same time, a sandwich structure is formed at the mesoscale in order to optimize the spatial distribution of the electric field and the polarization behavior synergistically. Owing to the synergistic improvement in dielectric properties and dielectric strength, the composite film achieved a discharge energy density of 6.65 J/cm3 and a charge-discharge efficiency of 85.27% under conditions of 150℃ and 510 MV/m, providing new insights into the structural design and performance optimization of high-temperature polymer dielectric materials.