Ultra-high energy density in all-organic copolymeric blends by grain refinement

Abstract

In order to broaden the application of dielectric capacitors for energy storage and solve the energy problem, the research and development of new dielectric materials with low dielectric loss, high breakdown strength and high energy density has become increasingly important. In this work, we innovatively designed all-organic poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP))/poly(vinylidene fluoride-chlorotrifluoroethylene) (P(VDF-CTFE)) copolymeric blends with tunable grain sizes by utilizing the steric effect and the interaction force of the copolymerized monomers of HFP and CTFE. The results showed that the chain spacing and grain size of the blend system were significantly reduced, resulting in an increase of crystallinity and advantageous phase transition. The P(VDF-HFP)/P(VDF-CTFE) 50/50 wt% obtained an ultra-high discharge energy density of 21.7 J cm⁻³ at the breakdown strength of 640 MV m⁻¹. The multiple enhancements in performance of the blend design by grain refinement demonstrate its promising prospects for high efficiency and scalability in thin film capacitors.