Spherical Sulfur-Infiltrated Carbon Cathode with a Tunable Poly(3,4-ethylenedioxythiophene) Layer for Lithium-Sulfur Batteries

Abstract

Li-S batteries have received significant attentionowingto their high energy density, nontoxicity, low cost, and eco-friendliness.However, the dissolution of lithium polysulfide during the charge/dischargeprocess and its extremely low electron conductivity hinder practicalapplications of Li-S batteries. Herein, we report a sulfur-infiltratedcarbon cathode material with a spherical morphology and conductivepolymer coating. The material was produced via a facile polymerizationprocess that forms a robust nanostructured layer and physically preventsthe dissolution of lithium polysulfide. The thin double layer composedof carbon and poly(3,4-ethylenedioxythiophene) provides sufficientspace for sulfur storage and effectively prevents the elution of polysulfideduring continuous cycling, thereby playing an essential role in increasingthe sulfur utilization rate and significantly improving the electrochemicalperformance of the battery. Sulfur-infiltrated hollow carbon sphereswith a conductive polymer layer demonstrate a stable cycle life andreduced internal resistance. The as-fabricated battery demonstratedan excellent capacity of 970 mA h g(-1) at 0.5 C anda stable cycle performance, exhibiting & SIM;78% of the initialdischarge capacity after 50 cycles. This study provides a promisingapproach to significantly improve the electrochemical performanceof Li-S batteries and render them as valuable and safe energydevices for large-scale energy storage systems.