Regulation of uniformity and electric field distribution achieved highly energy storage performance in PVDF-based nanocomposites via continuous gradient structure

PVDF-based nanocomposites have gained significant focus in capacitors for their excellent dielectric strength, its multi-scale structural inhomogeneity is the bottleneck for improving the energy storage performance. Here, the composite components are optimized by the matrix modification, BST (Ba0.6Sr0.4TiO3) ceramic fibrillation and surface coating. A series of PVDF/polymethyl methacrylate/lysozyme@BST nanofibers with continuous gradient distribution (PF-M/mBST nf-g) are prepared by the concentration gradient-biaxial high-speed electrospinning. The finite element simulation and experiment results indicate that the continuous gradient structure is favorable for the microstructure and inhomogeneity of the electric field distribution, significantly increasing the breakdown strength (Eb) and the permittivity (εr), as well as effectively suppressing the interfacial injected charge and leakage current. As a result, the energy storage density (Ue) of 23.1 J/cm3 at 600 MV/m with the charge-discharge efficiency (η) of 71% is achieved compared to PF-M (5.6 J/cm3@350 MV/m, 65%). The exciting energy storage performance based on the well-designed PF-M/mBST nf-g provides important information for the development and application of polymer nanocomposite dielectrics.