School of Materials Science and Engineering, Wuhan University of Technology, Wuhan, 430070, China.
State Key Laboratory of Power System, Department of Electrical Engineering, Tsinghua University, Beijing 100084, China.
Mater Horiz. 2023 Jun 6;10(6):2139-2148. doi: 10.1039/d2mh01511k.
Flexible polymer dielectrics for capacitive energy storage that can function well at elevated temperatures are increasingly in demand for continuously advancing and miniaturizing electrical devices. However, traditional high-resistance polymer dielectrics composed of aromatic backbones have a compromised band gap () and hence suffer from low breakdown strength and a huge loss at high temperatures. Here, based on the density functional theory (DFT) calculations, rigid and non-coplanar alicyclic segments are introduced into the polyimide backbone to overcome the incompatibility of a high glass transition temperature () and large . Thanks to the large optical (∼4.6 eV) and high (∼277 °C), the all-alicyclic polyimide at 200 °C delivers a maximum discharge energy density () of 5.01 J cm with a charge-discharge efficiency () of 78.1% at 600 MV m, and a record of 2.55 J cm at = 90%, which is 10-fold larger than that of the state-of-art commercial polyetherimides (PEIs). In addition, compared with aromatic polyimides, the all-alicyclic polyimide possesses a better self-clearing characteristic due to a smaller ratio of carbon to hydrogen and oxygen, which facilitates its long-term reliability in practical applications.
用于电容储能的柔性聚合物电介质在高温下仍能良好运行的需求日益增长，这是为了不断推进和小型化电子设备。然而，传统的由芳族骨架组成的高电阻聚合物电介质的带隙（）较小，因此其击穿强度和高温下的损耗都很大。在这里，基于密度泛函理论（DFT）的计算，刚性和非共面脂环段被引入聚酰亚胺骨架中，以克服高玻璃化转变温度（）和大的（）之间的不兼容性。得益于大的光学（∼4.6 eV）和高的（∼277°C），在 200°C 下的全脂环聚酰亚胺在 600 MV m 时具有 5.01 J cm 的最大放电能量密度（），充电-放电效率（）为 78.1%，在 = 90%时具有 2.55 J cm 的记录击穿强度，比最先进的商业聚醚酰亚胺（PEIs）大 10 倍。此外，与芳族聚酰亚胺相比，由于碳与氢和氧的比例较小，全脂环聚酰亚胺具有更好的自清除特性，这有利于其在实际应用中的长期可靠性。
