Dissociation and Diffusion of Glyme-Sodium Bis(trifluoromethanesulfonyl)amide Complexes in Hydrofluoroether-Based Electrolytes for Sodium Batteries,The Journal of Physical Chemistry C

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Dissociation and Diffusion of Glyme-Sodium Bis(trifluoromethanesulfonyl)amide Complexes in Hydrofluoroether-Based Electrolytes for Sodium Batteries
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2016-10-11 00:00:00 , DOI: 10.1021/acs.jpcc.6b06804
Shoshi Terada ₁ , Hiroko Susa ₁ , Seiji Tsuzuki ₂ , Toshihiko Mandai ₁ , Kazuhide Ueno ₁ , Yasuhiro Umebayashi ₃ , Kaoru Dokko _{1,

4} , Masayoshi Watanabe ₁

Affiliation

Physicochemical properties and battery performance of [Na(glyme)][TFSA] complexes (TFSA: bis(trifluoromethanesulfonyl)amide) dissolved in a hydrofluoroether (HFE) were investigated. Glyme (tetraglyme (G4) or pentaglyme (G5)) coordinates to Na⁺ to form a 1:1 complex [Na(G4 or G5)]⁺ cation. Raman spectroscopy revealed that the complex structure of [Na(glyme)]⁺ is maintained in the HFE solution, and free (uncoordinated) glymes are not liberated on adding HFE. HFE molecules are scarcely involved in the first solvation shell of Na⁺ because of their low electron-pair-donating ability. Raman spectra of the [TFSA]⁻ anion suggests that the attractive interaction between the complex [Na(glyme)]⁺ cation and [TFSA]⁻ anion is enhanced on adding HFE. The population of contact ion-pair (CIP) and/or aggregate (AGG) is smaller for the G5 system than for the G4 one, and the [Na(G5)][TFSA]/HFE has higher ionic conductivity. The self-diffusion coefficients of the [Na(glyme)]⁺ complex and [TFSA]⁻ were measured by pulsed field gradient (PFG) NMR, and the dissociativity of [Na(glyme)][TFSA] was assessed. The dissociativity of the G5 system is greater than that of the G4 one, and the dissociativity can be correlated with the attractive interaction between [Na(glyme)]⁺ and [TFSA]⁻, as evaluated by ab initio calculations. The dissociativity of the complexes gave significant effects on the battery performance.

中文翻译：

甘氨酸-双（三氟甲磺酰基）酰胺钠在氢氟醚基钠电池电解质中的解离和扩散

研究了[Na（glyme）] [TFSA]配合物（TFSA：双（三氟甲磺酰基）酰胺）溶解在氢氟醚（HFE）中的理化性质和电池性能。甘醇二甲醚（四甘醇二甲醚（G4）或五甘醇二甲醚（G5））与Na ⁺配位以形成1：1络合物[Na（G4或G5）] ⁺阳离子。拉曼光谱表明，[Na（glyme）] ⁺的复杂结构在HFE溶液中得以维持，加入HFE不会释放出游离的（未配位的）甘氨酸。HFE分子几乎不参与Na ⁺的第一个溶剂化壳层，因为它们的给电子对能力低。[TFSA] ^-阴离子的拉曼光谱表明，复合物[Na（glyme）] ⁺之间具有吸引作用添加HFE可以增强阳离子和[TFSA] ^-阴离子。对于G5系统，接触离子对（CIP）和/或聚集体（AGG）的数量比对于G4系统更小，并且[Na（G5）] [TFSA] / HFE具有更高的离子电导率。通过脉冲场梯度（PFG）NMR测量[Na（glyme）] ^+配合物和[TFSA] ^-的自扩散系数，并评估[Na（glyme）] [TFSA]的解离性。G5系统的离解性大于G4系统的离解性，并且从头算计算可以看出，该离解性可以与[Na（glyme）] ⁺和[TFSA] ^-之间的吸引相互作用相关。配合物的解离性对电池性能产生了显着影响。

更新日期：2016-10-11

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