Overcoming diffusion limitations in supercapacitors using layered electrodes
Overcoming diffusion limitations in supercapacitors using layered electrodes
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DOI：
10.1016/j.jpowsour.2019.04.107
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发表时间：
2019-09-01
影响因子：
9.2
通讯作者：
Duncan, S. R.
中科院分区：
文献类型：
--
作者：
Drummond, R.;Huang, C.;Duncan, S. R.
研究了多层电极微结构对电化学双层超级电容器动态电容的影响。首先开发了描述层状电极上的离子扩散和双层动力学的电化学模型，然后与实验数据进行匹配。使用 TiO2 颗粒和碳纳米管层状电极，在实验和模型模拟中的实电容图和虚电容图中观察到两个拐点频率。这两个拐点频率导致高频时实际电容增加（omega 近似为 10(0) - 10(2) rad s(-1)），但低频时实际电容减小（omega 近似为 10(-2) rad s(-1)），响应对相对层厚度基本上不敏感。高频下容量的增加是由于分层导致电极上的离子迁移率增加，从而克服了相同均质电极的扩散限制。这些结果意味着分层电极适用于具有高动态电荷分布和/或相对较厚的电极的应用。
The impact of multi-layered electrode microstructures on the dynamic capacitance of electrochemical double layer supercapacitors is investigated. An electrochemical model that describes ion diffusion and double layer dynamics across the layered electrodes is first developed and then matched to experimental data. With TiO2 particulate and carbon nanotube layered electrodes, two knee frequencies were observed in the real and imaginary capacitance plots in both experiment and model simulations. These two knee frequencies resulted in an increase in real capacitance at high frequencies (omega approximate to 10(0) - 10(2) rad s(-1)) but a reduction at lower frequencies (omega approximate to 10(-2) rad s(-1)), with the response being largely insensitive to the relative layer thicknesses. The increased capacity at high frequencies was due to increased ion mobility across the electrodes caused by the layering, allowing diffusion limitations of identical homogeneous electrodes to be overcome. These results imply the suitability of layered electrodes for applications with highly dynamic charge profiles and/or relatively thick electrodes.