Gel polymer electrolyte for Room temperature Sodium Sulfur batteries

Abstract

Sodium sulfur batteries have gained attention owing to the advantages of low cost and high specific capacity. However, the current electrolytes have a few main disadvantages, including sodium-dendrite growth, sulfur shuttling and electrolyte leakage, which hinder their practical application. Herein, we report the preparation of poly(vinylidene fluoride-co-hexafluoropropylene) based gel polymer electrolyte by a simple solution casting technique for room temperature sodium sulfur battery applications. The gel polymer electrolyte was activated by soaking the freshly prepared gel polymer membranes in a liquid electrolyte solution. The highly porous solution casting GPE exhibits a high ionic conductivity of 1.37 mS cm-1 at ambient temperature. The electrochemical stability window of 4.5V versus Na+/Na. Furthermore, sodium symmetric cells show stable stripping/plating of Na+ up to 3000 hours with transference number of 0.648. The cells achieved a specific capacity of 398 mAh g-1for the initial reversible discharge specific capacity and 75 mAh g-1 at cycle 200 with 99.9% Coulombic efficiency at 0.1C rate. Our results demonstrate the polymer electrolytes are a potential candidate for sodium sulfur batteries with desired performance.