Enhanced Energy Storage with Polar Vortices in Ferroelectric Nanocomposites
Enhanced Energy Storage with Polar Vortices in Ferroelectric Nanocomposites
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DOI：
10.1103/physrevapplied.8.034014
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发表时间：
2017-09-19
影响因子：
4.6
通讯作者：
Lookman, Turab
中科院分区：
文献类型：
--
作者：
Liu, Zhen;Yang, Bin;Lookman, Turab
铁电陶瓷填料与聚合物基纳米复合材料作为高储能介质电容器具有广阔的应用前景。然而，铁电填料的微观结构对纳米复合材料储能性能的影响还没有得到定量的研究，但它是理解提高电容器性能的方法的关键因素。我们展示了一种利用拓扑涡结构来提高纳米复合材料储能密度的策略。通过三维相场计算，我们证明了铁电纳米线中可以存在多涡旋结构，在填充物与基质的界面处不存在电荷缺陷或自由电荷。计算了外加电场作用下纳米圆柱线材的拓扑结构(涡旋和反涡旋对)的开关行为。由于涡旋结构，纳米复合材料的剩余极化很小，磁滞回线非常窄，可以大大提高能量密度，高达5J/cm(3)，而商用电容器的能量密度为1-2J/cm(3)，在相对较低的电场(140 mV/m)下，储能效率高(超过95%)。
Nanocomposites of ferroelectric ceramic filler and polymer matrix show considerable promise as high energy-storage dielectric capacitors. However, the influence of the microstructure of the ferroelectric filler on the electric energy-storage performance in the nanocomposite has not been quantitatively studied, yet it is a key element in understanding the methods employed to improve the performance of capacitors. We demonstrate a strategy to enhance the energy-storage density with topological vortex structures in nanocomposites. Using three-dimensional phase field calculations, we show that multivortex structures can exist in ferroelectric nanowires without charge defects or free charges at the interface between the filler and matrix. The switching behavior of the topological structure (vortex and antivortex pair) under external electric field is calculated in nanocylinder wires. The small remnant polarization and very narrow hysteresis loop due to the vortex structure in the nanocomposites can lead to a large enhancement of energy density, as high as 5 J/cm(3) compared to 1-2 J/cm(3) for commercial capacitors, and high energy-storage efficiency (over 95%) at a relatively low electric field of 140 MV/m.