Nanonet-/fiber-structured flexible ceramic membrane enabling dielectric energy storage

Abstract

Ceramics are considered intrinsically brittle at macro scale due to the lack of slip mechanism and pre-existing defects, which greatly limits their potential applications in emerging fields including wearable electronic devices and flexible display. In this contribution, we developed BiFeO₃/SiO₂ dual-networks with exceptional flexibility through a coupled electronetting/electrospun method. The hybrid nanostructured networks endow the material with high tensile strength (2.7 MPa), excellent flexibility (80% recoverable deformation), and robust fatigue resistance performance (maintain flexibility after a 1000-cyclic compress test). After <i>in-situ</i> compounded with dielectric polymer via a layer-by-layer solution casting method, the resultant three-dimensional (3D) composite film exhibits a twice higher dielectric constant (<i>ε</i>_r) than polyether imide (PEI) film. More importantly, the breakdown strength of the 3D composite film is almost the same as that of the PEI film, resulting in an enhanced energy density of ~6.0 J/cm³ and a high efficiency of 80% at 4.58 MV/cm. The unique structure, combined with the excellent balance between mechanical and dielectric properties in flexible structures, is of critical significance to the design of flexible functional ceramics and broadening their applications in wearable electric devices.