Polymer electrolytes based on magnesium triflate for quasi-solid-state magnesium-sulfur batteries

Abstract Herein, magnesium-ion conducting polymer electrolytes (PE) based on polyvinylidene fluoride (PVDF), tetraethylene glycol dimethyl ether (TEGDME), succinonitrile (SN), and different concentrations of magnesium triflate salt ((CF 3 SO 3 ) 2 Mg) were fabricated. The structural, optical, electrical, and electrochemical properties were investigated. The conductivity increases to about 10 −5 S.cm −1 with increasing the concentration of (CF 3 SO 3 ) 2 Mg up to 33 wt%, at room temperature. The ionic transference number for the matrix containing 33 wt% of (CF 3 SO 3 ) 2 Mg increases from ( t m g + 2 = 0.4) to ( t M g + 2 = 0.8 ) with increasing the temperature comparatively from room temperature to 55 °C. Also, the cell with 33 wt% of (CF 3 SO 3 ) 2 Mg shows low overpotential and steady Mg stripping/plating during the initial cycles at 55 °C. Polymer and dual electrolytes, as well as bare and modified Mg surface electrodes, are used to create Mg/S cells. The cell with a modified Mg surface electrode and dual electrolyte exhibit lower interfacial impedance, higher energy density, and charge-discharge capacity than the cell with a bare Mg electrode and polymer electrolyte.