Magnesium hexakis(methanol)-dinitrate complex electrolyte for use in rechargeable magnesium batteries

Abstract

Functional compatible electrolyte with Mg2+ intercalation cathodes represents one of the largest obstacles in the development of practical Mg batteries MBs. In current work, we report for the first time magnesium hexakis(methanol)-dinitrate complex (MHMD) electrolyte product reaction of 2,2-dimethoxypropane with magnesium nitrate hexahydrate via ‘Solvent-in-Salt’ method. 2,2-Dimethoxypropane as a water scavenger can capture reducible molecules like H2O and dehydrate Mg(NO3)2.6H2O to form magnesium hexakis(methanol)-dinitrate complex. Meanwhile, Mg cloud bonds will become weak—something which frees up the mobility of Mg2+. This electrolyte exhibits high ionic conductivity with low activation energy ~ 0.18 eV. The general aim of the investigation was to demonstrate a potential application of MHMD electrolyte in Mg-ion cell. Mg cells were analyzed with the use of cyclic voltammetry (CV), galvanostatic charging/discharging tests, and electrochemical impedance spectroscopy. A comparative study between different cathodes like V2O5, GeO2, TiO2, and S using MHMD electrolyte was performed. The S cathode has an initial discharge capacity of 370 mAh g−1 and retained a reversible capacity at 60 mAh g−1 after 20 cycles exhibiting better electrochemical performances than those of V2O5, GeO2, and TiO2 cathodes. This work opens up a new pathway to explore new electrolytic materials for MBs with high performance.