Dielectric and Energy Storage Properties of <scp>PEI</scp>/<scp>FPE</scp> Based Binary Blend Composite Films

ABSTRACT Polymer is the dielectric material of choice for dielectric capacitors. However, the low dielectric constant limits the polymer from achieving a satisfactory energy density. Therefore, researchers synergistically integrate a variety of components to effectively improve the energy storage performance. In this paper, Polyetherimide (PEI) and Fluorene Polyester (FPE) hybrid composite films are prepared by a linear/linear blending strategy. The dielectric constants of PEI and FPE are 3.38 and 3.45 at 10 Hz, and the dielectric constant is increased to 4.02 when the mass fraction of FPE is 10%. The breakdown field strength of PEI and FPE is 553.51 and 589.34 kV/mm, and the breakdown field strength reaches 746.51 kV/mm after blending. At 800 kV/mm, the energy storage density and energy storage efficiency of the hybrid composite film reach 11.38 J/cm 3 and 86.14%. Compared with PEI, the performance of the prepared blended composite film has been comprehensively improved, which provides a corresponding theoretical analysis and experimental strategy for the preparation of high‐performance all‐organic blended composite dielectric and also has potential application prospects in energy storage devices.