A surface-modified TiO2 nanorod array/P(VDF–HFP) dielectric capacitor with ultra high energy density and efficiency

Abstract

Dielectrics with high energy storage density and efficiency are of vital significance in modern electronic and electric power systems. Here, we designed a surface-modified TiO₂ nanorod array/P(VDF–HFP) dielectric capacitor through a simple hydrothermal, surface modification and spin-coating process. The obtained nanocomposite capacitor shows an ultrahigh energy density of 17.5 J cm⁻³ at 509 kV mm⁻¹, ∼9 times that of the benchmark BOPP (∼2 J cm⁻³). What is more, the composites can realize very high charge–discharge efficiency (86%) even at an electric field as high as ∼500 kV mm⁻¹. Our phase-field simulation results reveal the significance of arrays in promoting the polarization and the interface between the array tips and the polymer in enhancing the energy density. The combination of nanorod arrays, non-ferrous fillers and surface modification provides an effective way to make dielectric composites viable in practical use.