Gradient structured all-organic dielectrics by electrospinning for enhanced energy storage performance

Abstract

Dielectric capacitors are widely used in the field of advanced electronic and power systems due to the advantages of high power density, robust safety, and long service life. The bottlenecks for the application of dielectric capacitors are low energy density and energy efficiency. In this work, a series of PVDF/P(VDF-TrFE-CTFE) composite dielectrics with different topological structures are designed and prepared by the electrospinning method. The electric field distribution and interface polarization are optimized by the spatial distribution of the dielectrics, as shown in the electrical tree simulation results. In particular, the linear gradient structured composite effectively reduces the leakage current density and increases the Young's modulus, obtaining the maximum discharge energy density of 17.75 J cm⁻³, which is 2.2 times that of the homogeneous structured composite. The corresponding energy efficiency is 70.26%, which is also higher than 57.67% of the homogeneous structured composite. In addition, this composite also demonstrated superior regional stability and charge–discharge performance. This investigation substantiates the strategic design of multi-layer structures as a method to escalate energy density in dielectric capacitors.