Ultra-High Capacitive Energy Storage Density at 150 °C Achieved in Polyetherimide Composite Films by Filler and Structure Design.

Guo, Yan; Zhao, Weichen; Li, Da; Liu, Jinnan; Qian, Jin; Pang, Lixia; Zhou, Tao; Liu, Wenfeng et al. · Adv Mater · 2025

basic_science · Level V

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Abstract

Polymer dielectrics are crucial for electronic communications and industrial applications due to their high breakdown field strength (E<sub>b</sub>), fast charge/discharge speed, and temperature stability. The upcoming electronic-electrical systems pose a significant challenge, necessitating polymeric dielectrics to exhibit exceptional thermal stability and energy storage capabilities at high temperatures. Here, ultra-high dielectric constant (ɛ<sub>r</sub>) and charge/discharge efficiency (η) of 0.55Bi<sub>0.5</sub>(Na<sub>0.84</sub>K<sub>0.16</sub>)<sub>0.5</sub>TiO<sub>3</sub>-0.45(Bi<sub>0.1</sub>Sr<sub>0.85</sub>)TiO<sub>3</sub> (BNKT-BST) ceramics are prepared by the solid-phase reaction method and added to polyetherimide (PEI) to form BNKT-BST/PEI nanocomposites with various structures. The findings indicate that the sandwich-structured BNKT-BST/PEI nanocomposite achieves the highest discharged energy density (U<sub>d</sub>) of 7.7 J cm<sup>-3</sup> with η of 80.2% when the E<sub>b</sub> is 650 MV m<sup>-1</sup> at 150 °C. This is primarily due to the incorporation of BNKT-BST nanoparticles and the multilayer structure design, which significantly improves the composite's ɛ<sub>r</sub> and E<sub>b</sub>. Additionally, the sandwich-structured composites show excellent cycling stability at 500 MV m<sup>-1</sup> and 150 °C, with U<sub>d</sub> of ≈ 4.7 J cm<sup>-3</sup> and η greater than 90%. The research presents nanocomposites with high energy storage density and excellent stability, crucial for the practical application of polymer dielectrics in high-temperature environments.