Significantly Enhanced Energy Storage Performances of PEI-based Composites Utilizing Surface Functionalized ZrO 2 Nanoparticles for High-Temperature Application

Polymer dielectrics with a high energy density and an available energy storage capacity have been playing an important role in advanced electronics and power systems. Nevertheless, the use of polymer dielectrics in harsh environments is limited by their low energy density at high temperatures. Herein, zirconium dioxide (ZrO 2 ) nanoparticles were decorated with amino group utilizing 4,4-methylenebis (phenyl isocyanate) (AMEO) and successfully incorporated into polyetherimide (PEI) matrix. The dielectric properties, breakdown strength, and energy storage performances of PEI/ZrO 2 -AMEO nanocomposites were investigated from 25 °C to 150 °C. It is found that the combination of moderate bandgap ZrO 2 with modest dielectric constant and polar groups at interface with deep trap can offer an available strategy to simultaneously increase the dielectric constant and breakdown strength of polymer dielectrics. As a result, the composites containing ZrO 2 -AMEO exhibit excellent energy storage performance at elevated temperatures. Specially, the PEI-based composites with 3 vol% ZrO 2 -AMEO display a maximum discharged energy density ( U d ) of 3.1 J/cm 3 at 150 °C, presenting 90% higher than that of neat PEI. This study may help to better develop the polymer-based dielectric composite applied at elevated temperatures.