Stable dielectric properties at high-temperature of Al2O3-PESU composite for energy storage application

Dielectric capacitors, crucial in microelectronics, hybrid vehicles and inverters, are renowned for their rapid charge–discharge capabilities and high energy density. This research introduces a novel strategy to enhance the dielectric properties of polyethersulfone (PESU) matrix materials by incorporating aluminum oxide (Al2O3) powder as a filler. Employing a solution mixing technique, dielectric composite films were synthesized. The dielectric constant increased from 4.6 to 5.0 at 10 Hz and 40 °C. The 1 wt% Al2O3-PESU composite exhibited exceptional outcomes, boasting a charge–discharge efficiency of 62 % and an impressive energy storage density of 8.4 J/cm3 at 640 kV/mm. Finite element simulations validated enhanced thermal conductivity, reduced electric field distortion, and heightened breakdown strength in the composites. Additionally, cyclic aging demonstrated outstanding stability and reliability over 50,000 cycles. This study propels dielectric material design, charting a course for high-performance energy storage capacitors, accentuating the crucial influence of temperature on dielectric behavior.