Electrochemical performance of lithium gel polymer battery with nanostructured sulfur/carbon composite cathode

A gel polymer electrolyte was formed by trapping lithium bistrifluoromethane-sulfonamide in tetraethylene glycol dimethyl ether electrolyte in a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/poly(methylmethacrylate) (PMMA) polymer matrix. The electrochemical properties of the resulting gel were investigated. This electrolyte was used in a lithium polymer cell with a nanostructured sulfur/ketjen black binary composite cathode prepared by wet ball-milling and heat-treatment. The gel polymer battery exhibited a high specific capacity of 753.8 mA h g− 1 at the initial cycle, stable reversible cycling and a capacity retention about 80% over 40 cycles along with a high coulombic efficiency, while the liquid electrolyte cell, in comparison, had low capacity retention and coulombic efficiency. The performance enhancement was attributed to the suppression of shuttle effect by the gel polymer electrolyte leading to higher sulfur utilization in the cell.

► PVDF-HFP/PMMA based gel polymer electrolyte offers the high ionic conductivity. ► Gel polymer electrolytes show a good thermal and electrochemical stability. ► The S/KB composite cathode is prepared by wet ball-milling with heat-treatment. ► The Li/S battery with gel polymer electrolyte shows a good cycle performance.