School of Chemistry and Biological Engineering, University of Science & Technology Beijing, Beijing100083, P. R. China.
State Key Laboratory of Power System, Department of Electrical Engineering, Tsinghua University, Beijing100084, P. R. China.
ACS Appl Mater Interfaces. 2023 Jan 11;15(1):1105-1114. doi: 10.1021/acsami.2c18384. Epub 2022 Dec 30.
The great development potential of polymer dielectric capacitors in harsh environments urgently requires enhancing capacitive performance at high temperatures. However, the exponentially increased conduction loss at high temperature and high field results in a drastic drop in energy density and charge-discharge efficiency. Here, a bilayer-structured polyimide (PI) composite film containing a wide-band gap inorganic layer as a charge blocking layer is designed. The inorganic layer improves the charge trapping ability and regulates the charge mobility at the electrode/dielectric interface. The charge injection mechanism in the interface-optimized PI/boron nitride nanosheet (BNNS) composite films is investigated by finite element simulation, and the effect of the BNNS layer on high temperature conduction is further understood. An appropriate thickness of the charge blocking layer establishes an effective energy barrier. Therefore, the composite films exhibit significantly suppressed conduction loss and excellent capacitive performance at a high temperature. A high energy density of 4.37 J cm with efficiency of 92% is obtained at 200 °C and 500 MV m, which is superior to reported high-temperature dielectric polymers and their composite films. This work provides a promising approach to improve the energy storage performance of polymer materials at high temperatures.
在恶劣环境下，聚合物介电电容器具有巨大的发展潜力，这迫切需要提高其在高温下的电容性能。然而，高温和高电场下传导损耗呈指数级增加，导致能量密度和充放电效率急剧下降。在这里，设计了一种具有宽带隙无机层作为电荷阻挡层的双层结构聚酰亚胺（PI）复合薄膜。无机层提高了电荷俘获能力，并调节了电极/介电界面处的电荷迁移率。通过有限元模拟研究了界面优化的 PI/氮化硼纳米片（BNNS）复合薄膜中的电荷注入机制，并进一步了解了 BNNS 层对高温传导的影响。适当厚度的电荷阻挡层建立了有效的能量势垒。因此，复合薄膜在高温下表现出明显抑制的传导损耗和优异的电容性能。在 200°C 和 500 MV m 下，复合薄膜获得了 4.37 J cm 的高能量密度和 92%的高效率，优于已报道的高温介电聚合物及其复合薄膜。这项工作为提高高温下聚合物材料的储能性能提供了一种有前途的方法。
