Enhanced energy storage performance of all-organic sandwich structured dielectrics with FPE and P(VDF-HFP)

• A high-performance and easy-to-process layered all-organic composite structure was proposed. • The introduction of FPE can effectively restrain the dielectric loss of PVDF-based composites. • The redistribution of the electric field and the hindrance of the interface optimize the breakdown strength. • Double-improvement of energy storage density and efficiency have realize. Rational design of multilayer structures can greatly improve the breakdown strength and is thus an effective method to improve the energy density of all-organic polymers. In this paper, a simple hot-pressing method was used to combine P(VDF-HFP) with FPE to prepare an all-organic multi-layered composite film with a symmetric structure. The effects of the sandwich structure on the breakdown strength, dielectric properties, and energy storage properties of multilayer materials were investigated in depth. Compared with the single-layer P(VDF-HFP), the FPE on both sides of the composite significantly enhanced the breakdown strength and inhibited the dielectric loss. In particular, when the multi-layer structure composite film with intermediate layer P (VDF-HFP) thickness of 6 μm, the energy storage density and energy storage efficiency reach 11.0 J/cm 3 and 86.7%, respectively, realizing double-improvement. This work can provide reliable theoretical analysis and experimental guidance for the preparation of high-performance flexible all-organic dielectrics.