A Hybrid Material Approach Toward Solution-Processable Dielectrics Exhibiting Enhanced Breakdown Strength and High Energy Density
A Hybrid Material Approach Toward Solution-Processable Dielectrics Exhibiting Enhanced Breakdown Strength and High Energy Density
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DOI：
10.1002/adfm.201501070
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发表时间：
2015-06-17
影响因子：
19
通讯作者：
Wang, Qing
中科院分区：
文献类型：
--
作者：
Han, Kuo;Li, Qi;Wang, Qing
对于紧凑型电子和电力系统的不断增长的需求不能用具有有限能量密度的常规介电材料来满足。通过将陶瓷添加剂掺入聚合物基体中，已经做出了许多努力来提高陶瓷的能量密度。尽管增加的结晶性，如此制造的聚合物纳米复合材料通常遭受显著降低的击穿强度，这妨碍了能量密度的实质性增益。本文介绍了一种新型的介电材料--有机-无机杂化材料，它是通过原位溶胶-凝胶缩合将钽物种共价结合到铁电聚合物中而制备的。具有最佳组成的溶液处理的杂化物表现出505 MV m（-1）的威布尔击穿强度和18 J cm（-3）的放电能量密度，这分别比原始铁电聚合物高出40%和180%以上。这种上级性能主要归因于在分子水平上在杂化物中产生的深陷阱，这导致了降低的导电性和较低的剩余极化。同时，交联网络的形成增强了杂化膜的机械强度，从而阻碍了机电击穿的发生。这项工作为具有高能量密度的溶液处理有机材料的电容式电能存储开辟了新的机会。
The ever-increasing demand for compact electronics and electrical power systems cannot be met with conventional dielectric materials with limited energy densities. Numerous efforts have been made to improve the energy densities of dielectrics by incorporating ceramic additives into polymer matrix. In spite of increased permittivities, thus-fabricated polymer nanocomposites typically suffer from significantly decreased breakdown strengths, which preclude a substantial gain in energy density. Herein, organic-inorganic hybrids as a new class of dielectric materials are described, which are prepared from the covalent incorporation of tantalum species into ferroelectric polymers via in situ sol-gel condensation. The solution-processed hybrid with the optimal composition exhibits a Weibull breakdown strength of 505 MV m(-1) and a discharged energy density of 18 J cm(-3), which are more than 40% and 180%, respectively, greater than the pristine ferroelectric polymer. The superior performance is mainly ascribed to the deep traps created in the hybrids at the molecular level, which results in reduced electric conduction and lower remnant polarization. Simultaneously, the formation of the cross-linked networks enhances the mechanical strengths of the hybrid films and thus hinders the occurrence of the electromechanical breakdown. This work opens up new opportunities to solution-processed organic materials with high energy densities for capacitive electrical energy storage.