Solvation of Magnesium Ion in Triglyme-Based Electrolyte Solutions

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• 作者：Toshiki Kimura ; Kenta Fujii ; Yoshiki Sato ; Masayuki Morita ; Nobuko Yoshimoto
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：August 20, 2015
• 年：2015
• 卷：119
• 期：33
• 页码：18911-18917
• 全文大小：398K
• ISSN：1932-7455

文摘

We report here structural study on solvation of Mg²⁺ ion in triglyme (G3)-based solutions applying as a novel electrolyte for rechargeable Mg batteries. In Mg(TFSA)₂/G3 electrolyte solutions (TFSA = bis(trifluoromethanesulfonyl)amide), we found from Raman spectroscopy that Mg²⁺ ion is solvated with two G3 molecules to form [Mg(G3)₂]²⁺ complexes. No direct coordination of TFSA^{鈥?/sup> anion to Mg2+ ion occurs in the solutions with the salt concentrations c_Mg = 0鈥?.60 M. The geometries and interaction energies for the [Mg(G3)₂]2+ were evaluated by DFT calculations and indicated that G3 molecules in the most stable complex act as a tridentate ligand, i.e., octahedral [Mg(tri-G3)₂]2+. However, the Raman spectra implies that [Mg(tri-G3)₂]2+ coexists with [Mg(tetra-G3) (bi-G3)]2+ in the solutions where tetra-G3 and bi-G3 are G3 molecules acting as tetra- and bidentate ligands, respectively, in the solvation sphere. The Walden plots indicated that the dissociativity (or ionicity) of Mg(TFSA)₂ in G3 solutions increases with increasing c_Mg, which is opposite to conventional organic electrolyte solutions but is similar to the LiTFSA/glyme solutions.}