Decoupling thermal stability and insulation in dielectric polymers via donor-acceptor rearrangement.

Wan, Yuting; Luo, Hang; Yan, Zhongna; Shen, Shuyi; Peng, Jiajun; Li, Xiaona; He, Guanghu; Zhang, Dou et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

Polymer dielectrics with enhanced thermal stability and electrical insulation are urgently needed for capacitive energy storage applications in electric power systems. There is a persistent challenge to break the contradictory correlation between high heat resistance and low electrical conduction in polymers. Here, we employ benzyl-induced crosslinking to rearrange short-range structural units in polyimide chains, reducing electrical conduction loss. The designed polymer exhibits an electrical conductivity more than 3 orders of magnitude lower than that of commercial heat-resistant polymers, while its glass transition temperature (T<sub>g</sub>) increases from 236.31 °C (for polyetherimide) to 289.72 °C. Consequently, a discharged energy densities of 6.38 J cm<sup>-3</sup> and 3.04 J cm<sup>-3</sup>, with charge-discharge efficiencies above 90%, are achieved at 200 °C and 250 °C, respectively, demonstrating among the best in all-organic dielectric polymers. This work presents a feasible approach to break the adverse correlation between thermal stability and electrical insulation in polyimide materials.