Polymer dielectrics with excellent thermal stability are the essential core material for thin film capacitors applied in a harsh-environment. However, the dielectric and mechanical properties of polymers are commonly deteriorated with temperature rising. Herein, polyetherimide (PEI)-based nanocomposites contained with SiO₂ nanoparticles (SiO₂-NPs) are fabricated by a solution casting method. It is found that the introduction of SiO₂-NPs decreases the electric conductivity and significantly enhances the breakdown strength of the nanocomposites, especially under high temperatures. As a result, the 5 vol% PEI/SiO₂-NPs nanocomposite film displays a superior dielectric energy storage performance, e.g., a discharged energy density of 6.30 J cm^-3 and a charge–discharge efficiency of 90.5% measured at 620 MV m^-1 and 150 °C. In situ scanning Kelvin probe microscopy characterization indicates that the charge carriers can be trapped in the interfacial regions between the polymer matrix and the SiO₂-NPs till the temperature reaches as high as 150 °C. This work demonstrates an effective strategy to fabricate high-temperature dielectric polymer nanocomposites by embedding inorganic nanoparticles and provides a method for directly detecting charge behavior at the nanoscale inside the matrix.

中文翻译：

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在具有超高能量密度和高温放电效率的聚醚酰亚胺/SiO2纳米复合材料中具有出色的稳定性

具有优异热稳定性的聚合物电介质是应用于恶劣环境的薄膜电容器必不可少的核心材料。然而，聚合物的介电和机械性能通常会随着温度升高而恶化。在此，通过溶液浇铸法制备含有SiO ₂纳米颗粒（SiO ₂ -NPs）的基于聚醚酰亚胺（PEI）的纳米复合材料。发现SiO ₂ -NPs的引入降低了纳米复合材料的电导率并显着提高了击穿强度，尤其是在高温下。结果，5 vol% PEI/SiO ₂-NPs纳米复合薄膜表现出优异的介电储能性能，例如在620 MV m ^-1和150°C下测得的6.30 J cm ^-3放电能量密度和90.5%的充放电效率。原位扫描开尔文探针显微镜表征表明，电荷载流子可以被捕获在聚合物基质和 SiO ₂ -NPs 之间的界面区域，直到温度高达 150 °C。这项工作展示了一种通过嵌入无机纳米粒子来制备高温介电聚合物纳米复合材料的有效策略，并提供了一种直接检测基体内部纳米级电荷行为的方法。