Effect of Li salt addition on electrochemical properties of poly(ethylene carbonate)-Mg salt electrolytes

Abstract

We report the ion-conductive and electrochemical properties of solid polymer electrolytes (SPEs) based on poly(ethylene carbonate) (PEC) and magnesium bis(trifluoromethanesulfonyl)imide, Mg(TFSI)2, with the inclusion of small amounts of lithium bis(fluorosulfonyl)imide, LiFSI. The addition of LiFSI improved the ionic conductivity of PEC-Mg(TFSI)2 from ~2.3 × 10−6 S cm−1 to ~1.0 × 10−5 S cm−1 at 80 °C. Cyclic voltammetry revealed that the plating/stripping reaction of Mg is enhanced by the addition of LiFSI. Linear sweep voltammetry found that the addition of LiFSI has no negative influence on the electrochemical oxidation stability of the electrolyte, which reached 2 V vs. Mg/Mg2+. The addition of a small amount of LiFSI proves to be an effective method for enhancing the ion-conductive and electrochemical performance of PEC-based Mg electrolytes. Ion-conductive and electrochemical properties of solid polymer electrolytes based on poly(ethylene carbonate) (PEC) and magnesium bis(trifluoromethanesulfonyl)imide, Mg(TFSI)2, with small amount of lithium bis(fluorosulfonyl)imide, LiFSI were investigated. The addition of LiFSI improved the ionic conductivity of PEC-Mg(TFSI)2, from ~2.3 × 10−6 S cm−1 to ~1.0 × 10-5 S cm−1 at 80 °C. Cyclic voltammetry measurements for PEC-based electrolytes revealed that the plating/stripping reaction of Mg/Mg2+ is enhanced by the addition of LiFSI.