Achieving Excellent Dielectric and Energy Storage Performance in Core-Double-Shell-Structured Polyetherimide Nanocomposites

The development of pulse power systems and electric power transmission systems urgently require the innovation of dielectric materials possessing high-temperature durability, high energy storage density, and efficient charge-discharge performance. This study introduces a core-double-shell-structured iron(II,III) oxide@barium titanate@silicon dioxide/polyetherimide (Fe₃O₄@BaTiO₃@SiO₂/PEI) nanocomposite, where the highly conductive Fe₃O₄ core provides the foundation for the formation of microcapacitor structures within the material. The inclusion of the ferroelectric ceramic BaTiO₃ shell enhances the composite's polarization and interfacial polarization strength while impeding free charge transfer. The outer insulating SiO₂ shell contributes excellent interface compatibility and charge isolation effects. With a filler content of 9 wt%, the Fe₃O₄@BaTiO₃@SiO₂/PEI nanocomposite achieves a dielectric constant of 10.6, a dielectric loss of 0.017, a high energy density of 5.82 J cm^-3, and a charge-discharge efficiency (η) of 72%. The innovative aspect of this research is the design of nanoparticles with a core-double-shell structure and their PEI-based nanocomposites, effectively enhancing the dielectric and energy storage performance. This study provides new insights and experimental evidence for the design and development of high-performance dielectric materials, offering significant implications for the fields of electronic devices and energy storage.