Elucidating Zn, Mg, and Ca Electrodeposition Mechanisms in Nonaqueous Electrolytes for Next-Generation Metal Batteries
Elucidating Zn, Mg, and Ca Electrodeposition Mechanisms in Nonaqueous
Electrolytes for Next-Generation Metal Batteries
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阐明下一代金属电池非水电解质中锌、镁和钙的电沉积机制
DOI：
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
A. Gewirth
中科院分区：
文献类型：
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作者：
Kim Ta;Kimberly A. See;A. Gewirth
采用循环伏安法和超微电极线性扫描伏安法研究了锌和镁的电沉积过程及其机理。在Pt UME处从三氟甲基磺酰亚胺（TFSI-）和含氯化物的电解质在乙腈中进行Zn电还原获得的CV表现出与扫描速率无关的电流密度，正如在UME处的简单电子转移所预期的那样。然而，从三种不同的含镁电解质在THF中获得的CV表现出扫描速率和电流密度之间的反比关系。基于COMSOL的模拟表明，Zn电沉积通过简单的一步，两个电子转移（E）机制进行。或者，Mg的结果最好通过调用电子转移之前的化学步骤来描述：化学电化学（CE）机制。化学步骤的活化能为51 kJ/mol。这一化学步骤很可能是氯桥二聚体[Mg 2（μ-Cl）3·6 THF]+前体的缩合反应。
Cyclic voltammetry and linear sweep voltammetry with an ultramicroelectrode (UME) were employed to study Zn and Mg electrodeposition and the corresponding mechanistic pathways. CVs obtained at a Pt UME for Zn electroreduction from a trifluoromethylsulfonyl imide (TFSI–) and chloride-containing electrolyte in acetonitrile exhibit current densities that are scan rate independent, as expected for a simple electron transfer at a UME. However, CVs obtained from three different Mg-containing electrolytes in THF exhibit an inverse dependence between scan rate and current density. COMSOL-based simulation suggests that Zn electrodeposition proceeds via a simple one-step, two-electron transfer (E) mechanism. Alternatively, the Mg results are best described by invoking a chemical step prior to electron transfer: a chemical–electrochemical (CE) mechanism. The chemical step exhibits an activation energy of 51 kJ/mol. This chemical step is likely the disproportionation of the chloro-bridged dimer [Mg2(μ–Cl)3·6THF]+ pre...