Functionalized Carbon as Polysulfide Traps for Advanced Lithium–Sulfur Batteries

Rechargeable lithium–sulfur batteries could be qualified to solve the energy needs of the present society simply by raising the specific capacity of the battery packs and could be made as a cost-effective technology by virtue of the abundant, safe, and economically viable sulfur. However, the polysulfide dissolution related issue in the lithium–sulfur battery is the major hurdle which needs to be reduced prior to the acceptance of rechargeable lithium–sulfur technology as a practically viable and feasible strategy to ensure efficient energy storage mechanisms. Toward this direction, we study the effect of oxidative functionalization and effect of temperature on the cyclability of lithium–sulfur battery as a function of their role in reducing the polysulfide dissolution by using EIS technique. The study demonstrates the reversible cycling of lithium–sulfur battery at 40 °C, wherein the cell delivers a discharge capacity of 750 mA h g –1 at a high current of 750 mA g –1 and tolerates up to 7.5 A g –1 current rate with the 60 wt % sulfur loaded functionalized carbon cathode. Our findings reflect the advantageous effect of surface functionalization on the performance of lithium–sulfur battery and the importance of EIS spectroscopy in understanding the mechanism associated with the reversible electrochemical process.