Enhanced depolarization energy release in gamma-irradiated LDPE/ZIF-8 composite via increased charge trapping

Abstract

The charging of dielectric materials such as polymers results in relatively low energy densities compared to conventional electrochemical batteries. However, dielectric-based systems are less prone to chemical aging and more stable at elevated temperatures, making them suitable for applications requiring long-term stability. In this study, we demonstrate that low-density polyethylene (LDPE) can be modified to enhance the energy contribution of detrapping currents during depolarization, resulting in energy releases that exceed those of an ideal capacitor under identical electrostatic conditions. LDPE was combined with zeolitic imidazolate framework-8 (ZIF-8) filler and subsequently exposed to gamma irradiation to improve electrical conductivity and create additional charge-trapping sites. As-prepared and irradiated LDPE and LDPE/ZIF-8 composite thin films were charged in a weak DC field (∼6 V/mm). During charging, one side of the film was in direct contact with the negative electrode, while the opposite side was separated from the positive electrode by an air gap. Depolarization measurements were performed using the same setup. The study examines the effects of filler addition and/or irradiation doses on the accumulated charge and the energy released from LDPE. A key finding is that gamma irradiation of the LDPE/ZIF-8 composite significantly enhances the contribution of detrapping currents to the overall energy release during depolarization. For the 300 kGy-irradiated LDPE/ZIF-8 composite, detrapping currents account for approximately 30 % of the total energy released.