Guo Ru, Yuan Xi, Zhou Xuefan, Chen Haiyan, Xie Haoran, Hu Quan, Luo Hang, Zhang Dou
Powder Metallurgy Research Institute, State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China.
Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, Hong Kong, China.
Polymers (Basel). 2025 Jan 31;17(3):390. doi: 10.3390/polym17030390.
Dielectric capacitors offer immense application potential in advanced electrical and electronic systems with their unique ultrahigh power density. Polymer-based dielectric composites with high energy density are urgently needed to meet the ever-growing demand for the integration and miniaturization of electronic devices. However, the universal contradictory relationship between permittivity and breakdown strength in traditional ceramic/polymer nanocomposite still poses a huge challenge for a breakthrough in energy density. In this work, all-organic carbon quantum dot CDs were synthesized and introduced into a poly(vinylidene fluoride) PVDF polymer matrix to achieve significantly boosted energy storage performance. The ultrasmall and surface functionalized CDs facilitate the polar -phase transition and crystallinity of PVDF polymer and modulate the energy level and traps of the nanocomposite. Surprisingly, a synergistic dielectric enhancement and loss reduction were achieved in CD/PVDF nanocomposite. For one thing, the improvement in and high-field originates from the CD-induced polar transition and interface polarization. For another thing, the suppressed dielectric loss and high-field are attributed to the conductive loss depression via the introduction of deep trap levels to capture charges. More importantly, was largely strengthened from 521.9 kV mm to 627.2 kV mm by utilizing the coulomb-blockade effect of CDs to construct energy barriers and impede carrier migration. As a result, compared to the 9.9 J cm for pristine PVDF, the highest discharge energy density of 18.3 J cm was obtained in a 0.5 wt% CD/PVDF nanocomposite, which is competitive with most analogous PVDF-based nanocomposites. This study demonstrates a new paradigm of organic quantum dot-enhanced ferroelectric polymer-based dielectric energy storage performance and will promote its application for electrostatic film capacitors.
介电电容器凭借其独特的超高功率密度在先进电气和电子系统中具有巨大的应用潜力。迫切需要具有高能量密度的聚合物基介电复合材料，以满足电子设备集成和小型化不断增长的需求。然而，传统陶瓷/聚合物纳米复合材料中介电常数与击穿强度之间普遍存在的矛盾关系，仍然对能量密度的突破构成巨大挑战。在这项工作中，合成了全有机碳量子点CDs，并将其引入聚偏氟乙烯PVDF聚合物基体中，以显著提高储能性能。超小且表面功能化的CDs促进了PVDF聚合物的极性相转变和结晶度，并调节了纳米复合材料的能级和陷阱。令人惊讶的是，在CD/PVDF纳米复合材料中实现了协同介电增强和损耗降低。一方面，介电常数和高场性能的提高源于CD诱导的极性转变和界面极化。另一方面，介电损耗的抑制和高场性能归因于通过引入深陷阱能级捕获电荷来降低传导损耗。更重要的是，通过利用CDs的库仑阻塞效应构建能量势垒并阻碍载流子迁移，击穿强度从521.9 kV/mm大幅提高到627.2 kV/mm。结果，与原始PVDF的9.9 J/cm³相比，在0.5 wt%的CD/PVDF纳米复合材料中获得了最高放电能量密度18.3 J/cm³，这与大多数类似的基于PVDF的纳米复合材料具有竞争力。这项研究展示了有机量子点增强铁电聚合物基介电储能性能的新范例，并将促进其在静电薄膜电容器中的应用。
