本项目针对如何在保持聚酰亚胺（PI）高性能的同时协同提高介电强度和介电常数的难点问题，首先，利用石墨烯中预先引入的氮杂原子催化周围碳原子氟化反应，促使C-F局部聚集，制得氟化区和芳香区共存异质结构FG，以提高C-F共价键属性，克服低氟化FG的C-F无法发生接枝反应的缺点；明晰氮杂原子对氟化反应历程、C-F分布和价键属性的影响规律。然后，通过C-F共价键在溶剂还原效应下与PI的界面接枝反应，促使FG氟化区转变成接枝PI分子和残留C-F共存的“接枝氟化区”，增强复合界面相容性、抑制空间电荷聚集，并“隔离”芳香区，防止其堆积，进而提高介电强度；同时，利用芳香区中π电子及其微电容结构提高介电常数。最终，制得高能量密度高性能PI薄膜。探究复合薄膜中FG接枝氟化区与芳香区共存异质结构的介电限域和空间电荷均化效应，及其对介电强度和介电常数的影响规律和机制，为制备高能量密度的高性能介电储能材料提供借鉴。

Maintaining polyimide's (PI) high performance and improving the dielectric strength and constant synergistically is still a challenging topic in the area of advanced PI dielectric materials. In this work, nitrogen atoms that are pre-doped into graphene sheet are employed to catalyze the fluorination of adjacent carbon atoms in graphene. The C-F bonds aggregate in the vicinity of doped nitrogen atom forming fluorinated region, while the un-fluorinated carbon atoms generate the aromatic region. As a result, the as-prepared fluorinated graphene (FG) presents heterostructure that is composed of fluorinated region and aromatic region. In this case, the covalent bonding nature of C-F bonds is enhanced, which thus improve the grafting reactivity of C-F bonds in the partly fluorinated FG. The fluorination reaction of nitrogen doped graphene is thoroughly studied aiming to reveal the influence of nitrogen on fluorinating mechanism, C-F distribution, and bonding nature. Then, the C-F bonds are allowed to react with PI under the reduction effect of solvent during the composite process, making the grafting of PI macromolecules on the FG sheets. The fluorinated region of FG is consequently transformed into a “grafted fluorinated region” containing grafted PI macromolecules and residual C-F bonds. This enhances the interface compatibility of composite film and inhibits the accumulation of space charge at interface. Meanwhile, the grafted fluorinated regions isolate the aromatic regions and prevent their accumulation. Therefore, the dielectric strength of the composite film is expected to be enhanced. In addition, the highly polarizable π-electron in the aromatic regions and microcapacitor structure in the composite film are used to improve the dielectric constant and thus prepare high performance PI film with a high energy density. Herein, the dielectric confinement and homogenizing space charge effect of the new heterostructure composed of grafted fluorinated region and aromatic region are explored in order to elucidate the relationship between the structure and the dielectric properties of PI/FG composite film. It is hoped that these findings can provide a reference for the preparation of high performance dielectric materials with a high energy density.