The performance of many electrochemical energy storage systems can be compromised by the formation of metal dendrites during charging. Additives in the electrolyte represent a useful strategy to mitigate dendrite formation, but understanding the mechanisms involved requires knowledge of the nanoscale effects of additives during electrochemical deposition. Here we quantify the effects of an inorganic additive on the morphology of an evolving electrochemical growth front, using liquid cell electron microscopy to provide the necessary spatial and temporal resolution. We examine deposition of ZnAu on Au in the presence of Bi additive, and show that low concentrations of Bi delay but do not prevent the formation of growth front instabilities. We describe a model in which Bi segregates at the growth front and promotes the surface diffusion and relaxation of Zn, allowing better coverage of the initial Au electrode surface. A more precise knowledge of the mechanism of inorganic additive effects may help in designing electrolyte chemistry for battery and other applications where morphology control is essential.

中文翻译：

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ZnAu电沉积过程中通过Bi添加剂控制生长前沿的演变

在充电过程中，金属树枝状晶体的形成会损害许多电化学能量存储系统的性能。电解质中的添加剂代表减轻树枝状晶体形成的有用策略，但是要了解所涉及的机理，需要了解电化学沉积过程中添加剂的纳米级效应。在这里，我们使用液体电池电子显微镜提供必要的时空分辨率，量化了无机添加剂对不断发展的电化学生长前沿形态的影响。我们研究了在Bi添加剂存在下Au上ZnAu的沉积，并表明低浓度的Bi会延迟但不会阻止生长前沿不稳定性的形成。我们描述了一个模型，其中Bi在生长前沿偏析并促进Zn的表面扩散和弛豫，从而更好地覆盖了初始Au电极表面。对无机添加剂作用机理的更精确的了解可能有助于设计电解质化学，以用于电池和其他需要形态控制的应用。