Enhanced breakdown strength and energy density over a broad temperature range in polyimide dielectrics using oxidized MXenes filler

In this work, polyimide-based (PI) nanocomposites containing two-dimensional oxidized MXenes as filler exhibit obviously enhanced capacitive performances at elevated temperature. To decrease the aggregation, Ti3C2TX colloidal solution was directly introduced into PI matrix via in-situ polymerization method. Because of the strong electrostatic attraction to electrons, the charge can be captured by oxidized MXenes, resulting in suppressed leakage current and greatly improved breakdown strength. Therefore, the largest discharged energy density (Ud) of 8.67 J/cm3 and the efficiency of 84.1% are achieved at 648 kV/mm in 0.5-wt% oxidized MXenes/PI nanocomposites at room temperature, which is more than twice than that of pure PI. In high temperature, significantly increased Ud of 5.46 J/cm3 at 100 °C and Ud of 2.05 J/cm3 at 150 °C are obtained compared with the pure PI (1.28 J/cm3@100 °C). This research contributes to broadening the application of oxidized MXene in flexible dielectrics and providing an effective way for the preparation of high-performance dielectric polymer-based composites over a broad temperature range.