The potentiostatic current transients and the role of local diffusion fields in formation of the 2D lead dendrites from the concentrated electrolyte
The potentiostatic current transients and the role of local diffusion fields in formation of the 2D lead dendrites from the concentrated electrolyte
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DOI：
10.1016/j.jelechem.2014.12.020
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发表时间：
2015-02-15
影响因子：
4.5
通讯作者：
Zivkovic, Predrag M.
中科院分区：
文献类型：
--
作者：
Nikolic, Nebojsa D.;Popov, Konstantin I.;Zivkovic, Predrag M.
通过恒电位瞬变分析和扫描电子显微镜(SEM)分析，研究了铅在浓硝酸盐电解液中的恒电位沉积过程。结果表明，浓电解液中铅的形核过程遵循基于扩散控制生长的三维瞬时形核的Scharifker模型。文中还讨论了得到的依赖关系与该模型理论预测的偏差。在扩散控制电沉积过程中，形成了针状和蕨状的树枝晶，以及不规则形状的晶体(树枝晶的前体)。对这些树枝状结构的扫描电子显微镜分析表明，它们是二维生长的。针状枝晶的尺寸明显大于蕨类枝晶和不规则晶体的尺寸。虽然电沉积过程发生在宏观电极的线性扩散层内，但枝晶的形状和尺寸是由电沉积初期形成的突起尖端(球形扩散)和顶端(柱状扩散)周围形成的局部扩散场的影响决定的。比较了球形扩散控制和圆柱扩散控制条件下的生长速度，证明了球形扩散控制条件下的生长速度比圆柱扩散控制条件下的更快。讨论了电流密度分布对铅枝晶最终形态形成的影响。(C)2014爱思唯尔B.V.保留所有权利。
Electrodeposition of lead from the concentrated nitrate electrolyte in the potentiostatic regime of electrolysis has been investigated by the analysis of the potentiostatic current transients and scanning electron microscope (SEM). It was found that the process of Pb nucleation from the concentrated electrolyte follows Scharifker model based on the 3D (three-dimensional) instantaneous nucleation with diffusion-controlled growth. The deviations of the obtained dependencies from the theoretical prediction for this model have been also discussed. Needle-like and fern-like dendrites, as well as crystals of irregular shape (precursors of dendrites) were formed in the diffusion controlled electrodeposition. The SEM analysis of these dendritic forms revealed their 2D (two-dimensional) growth. The size of needle-like dendrites was considerably larger than the size of both the fern-like dendrites and the irregular crystals. Although the electrodeposition process occurred inside the linear diffusion layer of the macroelectrode, the shape and size of dendrites were determined by the effect of local diffusion fields formed around tips (spherical diffusion) and top edges (cylindrical diffusion) of protrusions formed in the initial stage of the electrodeposition. The growth rates under the conditions of spherical and cylindrical diffusion control were mutually compared and a faster growth under the conditions of the spherical, in relation to the cylindrical diffusion, was proved. The effect of the current density distribution on formation of the final forms of Pb dendrites was also discussed. (C) 2014 Elsevier B.V. All rights reserved.