Optimizing the Interdomain Spacing in Alicyclic Polythiourea toward High-Energy-Storable Dielectric Material

Organic dielectric materials have been widely developed and investigated for energy storage capacitors. However, challenges remain in terms of the relatively low dielectric constant and energy density. Enhancing the dipolar polarization to increase the dielectric constant is considered to be an effective way to improve the energy density of polymer dielectrics. Herein, enlightened by the chain-packing structure that affects the dipolar relaxation behavior, a simple and low-cost approach is proposed to tailor the interdomain spacing in an alicyclic polythiourea (PTU) by changing quenching temperatures and further facilitate the dipolar polarization. It is found that the large interdomain spacing is beneficial to promote the localized motion of segmental chains in amorphous regions, but at the same time inevitably reduces the dipole density. Therefore, in order to achieve the highest dielectric constant in the PTU, there is an optimal value for the interdomain spacing. It is worth noting that the dielectric constant of PTU increases from 5.7 to 10, and thus the energy density increases by 53% to 16.3 J cm^-3 . It proposes a simple and feasible strategy to further improve the energy density through optimizing the interdomain spacing toward high-energy-storable dielectric material.