Efficient polysulfide trapping enabled by a polymer adsorbent in lithium-sulfur batteries

Abstract

Lithium-sulfur (Li-S) batteries have been viewed as promising candidates for next-generation high-energy rechargeable batteries due to their high theoretical energy density. However, their practical application is severely impeded by the notorious shuttle effect of soluble polysulfides. Herein, a nature polymer of konjac glucomannan (KGM) was adopted as polysulfide-adsorbing agent by coating on carbon nanofiber (CNF) mats for polysulfide-trapping interlayers in Li-S batteries. A uniform coating method was developed by improving the wettability of CNFs to aqueous solutions using ethanol as a co-solvent of water. It is revealed that not only the KGM polymer itself but also the coating quality is critical to prevent polysulfide diffusion. With the improved coating quality and the strong chemisorption of KGM, the shuttle effect was effectively suppressed and excellent electrochemical performance was demonstrated with a high reversible capacity of 1286 mAh g−1 at 0.2C, good cycling stability with a capacity retention of 84% after 400 cycles at 1C and high rate capability. Our findings provide a facile way to address the shuttle behavior of Li-S batteries using low-cost and environmental friendly materials, which are very promising for large-scale energy storage applications.