BT@PDA enhancement of energy storage density with PEN composite dielectric material

In recent years, with the breakthroughs in nanomaterial technology and manufacturing processes, the energy density of energy storage devices has been significantly improved, laying the foundation for their large-scale commercial applications. Flexible dielectric energy storage materials have received extensive attention due to their advantages such as low processing difficulty, light weight, efficient charge–discharge processes, and excellent energy storage density. However, in polymer-based nanocomposites, there are problems such as poor dispersion of nanoscale fillers and the formation of physical defects, which in turn affect the mechanical properties. To address the above issues, in this study, through surface modification technology, insulating polydopamine (PDA) was coated on the surface of barium titanate (BaTiO 3 , BT) nanoparticles to synthesize functional BT core–shell particles, which were then doped into a polyarylether nitrile (PEN) matrix with good dielectric properties to prepare PEN/BT@PDA composite dielectric materials. The influence of surface-modified BT core–shell particles on the microstructure and energy storage performance of PEN-based composite dielectric materials was investigated. The results show that the BT@PDA particles are uniformly dispersed and have good compatibility within the PEN matrix. At the same time, the dielectric properties and breakdown performance of PEN/BT@PDA have also been improved. Under an electric field of 100 Hz, the maximum dielectric constant of the PEN/BT@PDA composite dielectric material is 6.8, which is a 74 % increase compared to the original PEN film, and the dielectric loss is 0.052, showing frequency dependence. The BT@PDA particles can capture the free electrons that are free in the PEN system under an electric field, reducing the carrier mobility, thus suppressing the formation of conductive paths inside the material, regulating the overall electric field distribution of the system, and improving the insulation performance of the composite film. Therefore, the breakdown strength of the PEN/BT@PDA composite dielectric material is increased, with the maximum breakdown strength being 180.9 kV/mm, which is a 14 % increase compared to the pure PEN film. Through calculation, the maximum energy storage density of the PEN/BT@PDA composite dielectric material is 0.78 J/cm 3 , which is an 81.4 % increase compared to the pure PEN. Under an external electric field of 120 kV/mm, the charge–discharge efficiency of the PEN/BT@PDA composite dielectric material can reach 69 %, demonstrating that BT@PDA can enhance the energy storage performance of PEN[30].