High-temperature polymer nanocomposites with high energy storage density (Ue) are promising dielectrics for capacitors used in electric vehicles, aerospace, etc. However, filler agglomeration and interface defects at high filler loadings significantly limit the enhancement of Ue and hamper the large-scale production of the nanocomposites. Here, polyetherimide (PEI) nanocomposites with nanoscale alumina (AO) at ultra-low contents were prepared via in situ polymerization from PEI monomers. We compared two composite dielectric preparation methods (in situ polymerization and ordinary solution blending) under the same conditions. In contrast to the nanocomposites obtained by blending PEI polymers with AO, the in situ nanocomposites exhibit substantially improved filler dispersion, together with largely suppressed conduction loss at high fields and high temperatures, leading to comprehensive enhancements of breakdown strength (Eb), charge-discharge efficiency (η) and Ue, simultaneously. The 0.3% (in volume) AO filled PEI nanocomposite film exhibits a superior Ue of 4.8 J/cm3 with η of 90% at 150 °C, which is 128% and 218% higher than those of pristine PEI and the ex situ PEI/AO nanocomposite film under the same conditions, respectively. This work provides a scalable strategy for the preparation of dielectrics with both good processability and excellent high-temperature energy storage performance.

中文翻译：

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原位聚合聚醚酰亚胺/Al2O3 纳米复合材料，显著提高高温下电容储能性能


具有高储能密度 （Ue） 的高温聚合物纳米复合材料是电动汽车、航空航天等电容器的前景广阔的电介质。然而，高填料负载下的填料团聚和界面缺陷显着限制了 Ue 的增强并阻碍了纳米复合材料的大规模生产。在这里，通过 PEI 单体原位聚合制备了具有超低含量纳米氧化铝 （AO） 的聚醚酰亚胺 （PEI） 纳米复合材料。我们比较了相同条件下的两种复合介电制备方法 （原位聚合和普通溶液共混）。与通过将 PEI 聚合物与 AO 共混获得的纳米复合材料相比，原位纳米复合材料表现出显着改善的填料分散性，同时在很大程度上抑制了高场和高温下的传导损耗，从而同时全面提高了击穿强度 （Eb）、充放电效率 （η） 和 Ue。在 150 °C 下，0.3%（体积）AO 填充的 PEI 纳米复合薄膜表现出 4.8 J/cm3 的优异 Ue，η为 90%，分别比原始 PEI 和非原位 PEI/AO 纳米复合薄膜高 128% 和 218%。这项工作为制备具有良好加工性和优异高温储能性能的电介质提供了一种可扩展的策略。