Charge-Discharge Performance of Rechargeable Organic-Magnesium Batteries Using Glyme-Based Electrolytes

Abstract

Rechargeable batteries composed of metallic Mg negative electrode, glyme-based electrolytes and organic positive electrode (2,5-dimethoxy-1,4-benzoquinone (DMBQ)) were proposed. The charge-discharge performance of the batteries was investigated using a coin-type cell at 30˚C. The discharge capacity reaches ca. 200 mAh g(DMBQ)-1 in Mg(TFSA)2/monoglyme and diglyme electrolytes. This capacity suggests that a multi-electron redox reaction takes place in these electrolytes. The hysteresis between charge-discharge voltage plateaus are quite large in Mg(TFSA)2/diglyme, triglyme and tetraglyme electrolytes, while the discharge voltage increases drastically after a few cycles in Mg(TFSA)2/monoglyme electrolyte. One of the reasons is that the overpotential of the Mg negative electrode for the Mg-dissolution is quite small. Although the capacity substantially decreases upon cycling, the cell using Mg(TFSA)2/monoglyme retains the high voltage at the discharge even after 20 cycles.