Conditioning–Free Electrolytes for Magnesium Batteries Using Sulfone–Ether Mixtures with Increased Thermal Stability

16 May 2018, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


We report an investigation of electrochemical properties and speciation of electrolytes composed of magnesium bis(hexamethyldisilazide) (Mg(HMDS)2) and magnesium chloride in sulfone-ether mixtures. The inclusion of sulfones dramatically increased the thermal stability of the electrolytes to 80 °C. The addition of ether was necessary to form an electrochemically active species. Electrochemical reversibility was maintained above 90% for 50 cycles for equivolume mixtures of butyl sulfone and THF. Sulfolane based solutions demonstrated low reversibilities and mass spectrometry measurements showed the preferential formation of an MgCl+ cation over the Mg2Cl3+ cation. Greater amounts of Mg2Cl3+ compared to MgCl+ is linked with higher performing electrolytes. Spectroscopic measurements showed co-solvation of the active magnesium cation with both solvents.


energy storage


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