Structural Analysis of Magnesium Chloride Complexes in Dimethoxyethane Solutions in the Context of Mg Batteries Research

Recently,
MgTFSI2/MgCl2 electrolyte solutions
in dimethoxyethane (DME) have been shown to function as viable electrolyte
solutions for secondary Mg batteries that can facilitate reversible
magnesium deposition/dissolution. MgCl2 is a crucial component
in these solutions. On its own, however, it is practically insoluble
in DME. Therefore, the fact that it is readily dissolved in MgTFSI2/DME solution is remarkable. Addition of MgCl2 greatly
improves the electrochemical performance of MgTFSI2/DME
electrolyte solutions. Thus, identifying the species formed in MgTFSI2/MgCl2 solutions is intriguing. In this study,
we implemented a wide variety of analytical tools, including single
crystal X-ray diffraction, multinuclear NMR, and Raman spectroscopy,
to elucidate the structure of these solutions. Various solution species
were determined, and a suitable reaction scheme is suggested.