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 ((CF3SO3)2Mg) 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 (CF3SO3)2Mg up to 33 wt%, at room temperature. The ionic transference number for the matrix containing 33 wt% of (CF3SO3)2Mg increases from ( = 0.4) to () with increasing the temperature comparatively from room temperature to 55 °C. Also, the cell with 33 wt% of (CF3SO3)2Mg 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.