The capacitive performance of existing dielectric polymers deteriorates significantly at elevated temperatures, although their thermal stability far exceeds, which remains a major challenge for efficient dielectric energy storage under extreme conditions. Here, a material design inspired by the cross-property connection phenomena, which bridges the seemingly unrelated material properties through similar or relevant determining microscopic factors, is reported to achieve substantially improved high-temperature capacitive performance in dielectric polymers. A high consistency is unveiled between the high-temperature electrical properties and thermal expansion of dielectric polymers, based on which a surface-gradient crosslinking structure is designed to inhibit the thermal distortion. It is confirmed by both experimental results and computational simulations that the restricted thermal expansion gives rise to reduced free volume as well as suppressed β-relaxation, which account for the marked improvements in high-temperature capacitive performances. At the optimal composition, the resultant polymer exhibits an ultrahigh discharged energy density up to 4.9 J/cm3 at 200 °C with a charge-discharge efficiency of 90 %, which is superior to all the existing polymer films based on the surface modification. This work highlights the significance of correlating variations in different physical properties for the design of high-energy-density polymer dielectrics capable of operating under harsh environments.

中文翻译：

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用于高温电容储能的具有限制热膨胀的表面梯度结构聚合物薄膜


现有介电聚合物的电容性能在高温下显着恶化，尽管其热稳定性远超，这仍然是极端条件下高效介电能存储的主要挑战。据报道，受交叉特性连接现象启发的材料设计通过相似或相关的决定微观因素桥接看似不相关的材料特性，从而显着改善了介电聚合物的高温电容性能。揭示了介电聚合物的高温电性能和热膨胀之间的高度一致性，在此基础上设计了表面梯度交联结构来抑制热变形。实验结果和计算模拟都证实，受限的热膨胀导致自由体积减小和β弛豫抑制，这是高温电容性能显着改善的原因。在最佳成分下，所得聚合物在 200 °C 时表现出高达 4.9 J/cm3 的超高放电能量密度，充放电效率为 90 %，优于所有基于表面改性的现有聚合物薄膜。这项工作强调了将不同物理特性的变化关联起来对于设计能够在恶劣环境下工作的高能量密度聚合物电介质的重要性。