Enhancement of the electrochemical stability of tetraglyme-Li[TFSA] electrolyte systems by adding [Bimps] zwitterion: An in-situ IV-SFG study
Enhancement of the electrochemical stability of tetraglyme-Li[TFSA] electrolyte systems by adding [Bimps] zwitterion: An in-situ IV-SFG study
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DOI：
10.1016/j.electacta.2020.137020
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发表时间：
2020-11-20
影响因子：
6.6
通讯作者：
Ouchi, Yukio
中科院分区：
文献类型：
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作者：
Qi, Chengzi;Iwahashi, Takashi;Ouchi, Yukio
在有和没有3-（1-丁基-1H-咪唑-3-鎓-3-基）丙烷1-磺酸盐（[Bimps]）两性离子的情况下，评估Pt/四甘醇二甲醚-双（三氟甲基磺酰基）氨基锂（Pt）/G4-Li[TFSA]）体系的电位依赖性界面结构，以了解[Bimps]对G4-Li[TFSA]电解质在Pt电极表面的电化学稳定性增强的影响。使用原位红外-可见和频发生（IV-SFG）光谱研究了上述界面结构。线性扫描伏安法（LSV）的结果表明，当[Bimps]引入时，G4-Li[TFSA]在Pt电极上的氧化极限向更高的电位移动，从而表明在G4-Li[TFSA]-[Bimps]体系中电化学窗口被扩展。G4-Li[TFSA]体系的SFG光谱证实，在1V（vs. Ag/Ag 7）下，游离G4分子和Li+-G4络合物阳离子主要吸附在Pt表面上。相比之下，将[Bimps]添加到G4-Li[TFSA]系统中，通过形成Li+-[Bimps]复合阳离子，即使在1V（相对于Ag/Ag+）下，也导致[Bimps]几乎完全覆盖Pt表面，并且没有观察到自由的G4分子。从头计算结果表明，自由态G4的最高占据分子轨道（HOMO）能级高于Li+-[Bimps]配合物阳离子的HOMO能级.这表明Li+-[Bimps]络合物比游离G4对氧化更稳定，这解释了具有[Bimps]添加剂的G4-Li[TFSA]体系的增强的电化学稳定性。(C)2020爱思唯尔有限公司保留所有权利。
The potential-dependent interfacial structures of Pt/tetraglyme-lithium bis(trifluoromethylsulfonyl) amide ((Pt)/G4-Li[TFSA]) systems were assessed with and without 3-(1-butyl-1H-imidazol-3-ium-3-yl)propane1-sulfonate ([Bimps]) zwitterions, to understand the impact of [Bimps] on the enhancement of the electrochemical stability of G4-Li[TFSA] electrolytes at Pt electrode surfaces. The aforementioned interfacial structures were investigated using in-situ infrared-visible sum frequency generation (IV-SFG) spectroscopy. The results of the linear sweep voltammetry (LSV) revealed that the oxidation limit of G4-Li[TFSA] at the Pt electrode shifted to a higher potential when [Bimps] was introduced, thus indicating that the electrochemical window is extended in the G4-Li[TFSA]-[Bimps] system. The SFG spectra of the G4-Li[TFSA] system confirmed that free G4 molecules and Li+-G4 complex cations are dominantly adsorbed on the Pt surface at 1 V (vs. Ag/Ag7). In contrast, the addition of [Bimps] to the G4-Li[TFSA] system resulted in almost full coverage of [Bimps] at the Pt surface by forming Li+-[Bimps] complex cations, even at 1 V (vs. Ag/Ag+), and no free G4 molecules were observed. The ab initio calculation indicated that the highest occupied molecular orbital (HOMO) energy level of free G4 was higher than that of the Li+-[Bimps] complex cation. This suggests that the Li+-[Bimps] complex was more stable for oxidation than the free G4, which accounts for the enhanced electrochemical stability of G4-Li[TFSA] system with [Bimps] additives. (C) 2020 Elsevier Ltd. All rights reserved.