Dendrite-free alkali metal electrodeposition from contact-ion-pair state induced by mixing alkaline earth cation
Dendrite-free alkali metal electrodeposition from contact-ion-pair state induced by mixing alkaline earth cation
复制标题
混合碱土阳离子诱导的接触离子对状态无枝晶碱金属电沉积
DOI：
10.1016/j.xcrp.2022.100907
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发表时间：
2022
影响因子：
8.9
通讯作者：
Ichitsubo Tetsu
中科院分区：
文献类型：
--
作者：
Li Hongyi;Murayama Masaki;Ichitsubo Tetsu
碱金属由于其极电位低、容量大，有望用于可充电金属阳极电池。然而，它们在充电时面临着众所周知的致命问题“树突生长”。在这里，我们详细研究了在碱金属电沉积中引入碱土盐来抑制枝晶生长的电解质。具体来说，以catfsa2为例，我们发现通过改变双阳离子电解质的溶剂化结构可以获得碱金属电沉积的无枝晶形貌。Ca2+的加入促进碱阳离子（Li+或Na+）与反阴离子形成接触离子对（cip），取代了通常存在于单阳离子电解质中的溶剂分离离子对。cip的强结合减缓了碱阳离子的脱溶动力学，因此，在反应受限的过程中实现了严格限制的碱金属电沉积，这是无枝晶形貌所必需的。
Alkali metals are expected to be used for rechargeable metal anode batteries owing to their low electrode potentials and large capacities. However, they face the well-known fatal problem of "dendritic growth" while charging. Here, we present a detailed investigation on electrolytes where alkaline earth salts are introduced to inhibit dendrite growth in alkali metal electrodeposition. Specifically, focusing on CaTFSA2as an exemplary additive, we reveal that dendrite-free morphology upon alkali metal electrodeposition can be attained by modifying the solvation structures in dual-cation electrolytes. Addition of Ca2+promotes alkali cation (Li+or Na+) to form the contact ion pairs (CIPs) with the counter anions, which replaces the solvent-separated ion pairs that commonly exist in single-cation electrolytes. The strong binding of the CIPs slows the desolvation kinetics of alkali cations and, consequently, realizes a severely constrained alkali metal electrodeposition in a reaction-limited process that is required for the dendrite-free morphology.