Theoretical interpretation of Warburg's impedance in unsupported electrolytic cells.
Theoretical interpretation of Warburg's impedance in unsupported electrolytic cells.
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无支撑电解池中 Warburg 阻抗的理论解释。
DOI：
10.1039/c7cp07101a
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
G. Barbero
中科院分区：
文献类型：
--
作者：
G. Barbero
我们讨论了仅含有一组正离子和一组负离子的无支撑电解池中Warburg阻抗的起源。我们的分析基于泊松-能斯特-普朗克模型，其中忽略了生成-重组现象。我们表明，为了观察Warburg-like阻抗，正离子的扩散系数必须与负离子的扩散系数不同，而且电极必须不阻塞。我们假设电极的非阻塞特性可以通过欧姆模型来描述，其中电池和外部电路之间的电荷交换是通过电极电导率来描述的。为简单起见，我们考虑一个对称单元。然而，我们的分析可以很容易地推广到更复杂的情况，其中电池不是对称的，电荷交换由Chang-Jaffe模型描述，或者由线性化的Butler-Volmer方程描述。我们的分析允许对先前由几个小组基于错误假设提出的Warburg阻抗表达式进行辩护。
We discuss the origin of Warburg's impedance in unsupported electrolytic cells containing only one group of positive and one group of negative ions. Our analysis is based on the Poisson-Nernst-Planck model, where the generation-recombination phenomenon is neglected. We show that to observe Warburg-like impedance the diffusion coefficient of the positive ions has to differ from that of the negative ones, and furthermore the electrodes have to be not blocking. We assume that the non-blocking properties of the electrodes can be described by means of an Ohmic model, where the charge exchange between the cell and the external circuit is described by means of an electrode conductivity. For simplicity we consider a symmetric cell. However, our analysis can be easily generalized to more complicated situations, where the cell is not symmetric and the charge exchange is described by the Chang-Jaffe model, or by a linearized version of the Butler-Volmer equation. Our analysis allows justification of the expression for Warburg's impedance proposed previously by several groups, based on wrong assumptions.