Tuning the MOF-derived Fe fillers and crystal structure of PVDF composites for enhancement of their energy storage density

Polymer-based capacitors are essential energy storage components in the electronic and electrical industries, which is benefit for their high power density and fast charge-discharge capabilities. However, the low energy density of polymer-based capacitors limits their miniaturization and intelligent applications. In this study, we present the novel poly(vinylidene fluoride) (PVDF)-based composites with exceptional energy storage performance at the submicron metal filler loadings. Guided by synergistically improving the dielectric constant and breakdown strength of polymer-based composites, metal-organic framework (MOF)-derived Fe fillers and Press & Heat (P&H) cycles are mainly implemented. The polymer-based composites exhibit a superior dielectric constant of 15.3, while simultaneously maintain a high breakdown strength of 617.1 MV/m. The excellent energy density of 28.9 J/cm3 is obtained at the ultralow filler loading of 0.2 wt%. Synergistic tuning the loading content of MOF-derived Fe and optimizing the P&H cycles not only leads to a novel composite dielectrics with outstanding energy storage properties, but also presents a new strategy for exploring high-performance capacitive polymer composites.