Achieving Superior High-Temperature Energy Storage Performance in Polycarbonate via Small Molecule Traps and Hydrogen Bonding

Abstract

The high-temperature performance of polymer capacitors plays a crucial role in the development of advanced electrical systems. However, at elevated temperatures, they face issues such as a significant increase in carrier transport, as well as a reduction in energy storage density and charge-discharge efficiency. To overcome this issue, this work successfully developed a fully organic polymer dielectric by incorporating the small molecule 4, 5,7,8,12,13,15,16octafluoro[2.2]paracyclophane (PF) into a polycarbonate (PC) matrix. Both theoretical calculations and experimental results demonstrate that PF, which possesses a wider bandgap than PC, can form electronic traps in conjunction with the polymer matrix. Furthermore, hydrogen bonding interactions between PF and PC act as effective trap hole for carrying charge carriers, thereby suppressing conduction losses at high temperatures. This synergistic effect enhances the breakdown strength of the polymer dielectric and improves its overall energy storage capacity. At 150 °C and an applied electric field of 540 kV/mm, the polymer dielectric achieves an energy storage density of 4.02 J/cm³ and a charge-discharge efficiency of 81%, while maintaining stable performance over 10,000 charge-discharge cycles. This work presents a promising strategy for the development of fully organic dielectrics with simultaneous high-temperature reliability and high energy storage performance.