Improved charge–discharge cycling durability of PVDF dielectrics with MgO nanofillers

Poly(vinylidene fluoride) (PVDF)-based dielectrics have drawn great attention for capacitor applications due to their high energy-storage density. However, compared to the constantly increasing energy-storage density made possible by different approaches, the issues of reliability, including their charge–discharge cycling durability, have not been adequately discussed and remain unsolved. In this study, the incorporation of a small amount of MgO nanoparticles, i.e., 5 wt. % MgO nanofillers, was proven to effectively improve the degradation of pure PVDF in the charge–discharge cycling test. The PVDF-5 wt. % MgO nanocomposites showed excellent stability after 1500 charge–discharge cycles at room temperature and 50 °C. Using the pulsed electro-acoustic method, the space charge suppression effect was observed in PVDF-5 wt. % MgO nanocomposites, which indicated that there was no distortion in the local electric field and helped enhance breakdown strength. At the same time, dielectric loss and AC conductivity were also significantly reduced, particularly at elevated temperatures. Such improvements in electrical properties are valuable, as they provide a direction for enhancing the reliability of PVDF-based composite dielectrics and enable their widespread application.