Governing Role of Solvent on Discharge Activity in Lithium-CO2 Batteries
Governing Role of Solvent on Discharge Activity in Lithium-CO2 Batteries
复制标题
溶剂对锂二氧化碳电池放电活性的控制作用
DOI：
10.1021/acs.jpclett.9b02615
复制
发表时间：
2019-11-07
影响因子：
5.7
通讯作者：
Gallant, Betar M.
中科院分区：
文献类型：
--
作者：
Khurram, Aliza;Yin, Yuming;Gallant, Betar M.
文献中报道的非水Li-CO2电池几乎完全依赖于基于甘醇二甲醚的电解质，导致假设它们对CO2放电具有独特的活性。在这里，我们研究电解质组成对CO2活性的影响，以检查是否是这种情况。结果表明，含有中等浓度的Li+盐（大致在本文研究的0.7-2 M的范围内）的基于TEGDME的电解质最有利于CO2活化，尤其是与基于二甲亚砜和碳酸丙烯酯的电解质相比。通过电化学，光谱和计算方法，我们确定甘醇二甲醚具有较低的去溶剂化能量的Li（+）相比，其他溶剂的候选人，而高盐浓度增加的局部密度Li+周围的CO2和还原中间体。这些属性共同增加了Li+的可用性，跨越了支持CO2活化所需的阈值。放电电压和反应速率也对碱性阳离子身份敏感，进一步激发其在启用或抑制反应性中的关键作用。
Non-aqueous Li-CO2 batteries reported in literature have almost exclusively relied upon glyme-based electrolytes, leading to a hypothesis that they are uniquely active for CO2 discharge. Here, we study the effect of electrolyte composition on CO2 activity to examine whether this is the case. The results indicate that TEGDME-based electrolytes containing moderate concentrations of Li+ salts (roughly within the range of 0.7-2 M examined herein) are most conducive to CO2 activation, especially compared to dimethyl sulfoxide and propylene carbonate-based electrolytes. Through electrochemical, spectroscopic, and computational methods, we determine that glymes have lower desolvation energies for Li(+ )compared to other solvent candidates, whereas high salt concentrations increase the local density of Li+ surrounding CO2 and reduction intermediates. These attributes collectively increase the availability of Li+, crossing a threshold necessary to support CO2 activation. Discharge voltage and reaction rates are also sensitive to the alkali cation identity, further invoking its key role in enabling or suppressing reactivity.