电解质
乙腈
溶剂化
无机化学
材料科学
电池(电)
化学
分子
物理化学
有机化学
热力学
电极
物理
功率(物理)
作者
Minjeong Shin,Heng‐Liang Wu,Badri Narayanan,Kimberly A. See,Rajeev S. Assary,Lingyang Zhu,Richard T. Haasch,Shuo Zhang,Zhengcheng Zhang,Larry A. Curtiss,Andrew A. Gewirth
标识
DOI:10.1021/acsami.7b11566
摘要
We evaluate hydrofluoroether (HFE) cosolvents with varying degrees of fluorination in the acetonitrile-based solvate electrolyte to determine the effect of the HFE structure on the electrochemical performance of the Li-S battery. Solvates or sparingly solvating electrolytes are an interesting electrolyte choice for the Li-S battery due to their low polysulfide solubility. The solvate electrolyte with a stoichiometric ratio of LiTFSI salt in acetonitrile, (MeCN)2-LiTFSI, exhibits limited polysulfide solubility due to the high concentration of LiTFSI. We demonstrate that the addition of highly fluorinated HFEs to the solvate yields better capacity retention compared to that of less fluorinated HFE cosolvents. Raman and NMR spectroscopy coupled with ab initio molecular dynamics simulations show that HFEs exhibiting a higher degree of fluorination coordinate to Li+ at the expense of MeCN coordination, resulting in higher free MeCN content in solution. However, the polysulfide solubility remains low, and no crossover of polysulfides from the S cathode to the Li anode is observed.
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