A Heterostructured Sulfonated CNT/Sulfur/CNT Cathode for Promoting the Binary Conversion of Polysulfides in Lithium-Metal Batteries

The shuttle effect of lithium polysulfides (LiPS) and sluggish redox kinetics hinder the commercialization of lithium-sulfur (Li-s) batteries. Herein, we design a lightweight and multifunctional multi-walled carbon nanotube (CNT)/sulfur/lithiated sulfonated CNT (M/S/M-SO3Li) electrode as energy storage devices. Flexible CNT films ensure continuously electron/ion transmission and serve as LiPS shielding layer. Moreover, guided by DFT and experimental results, SO3 groups exert a vital adsorption effect toward sulfur species but not NH4+ groups. The SO3 groups can not only employ as LiPS immobilizer by Li-O bands between LiPS and SO3 but also serve as multifunctional electrocatalyst to propel LiPS conversion via generating thiosulfate and polythionate and Li2S decomposition by reducing reaction overpotential. As expected, M/S/M-SO3Li electrode exhibits prominent rate capability (723.5 mAh g(-1) at 5 C), high sulfur loading (7.09 mAh cm(-2) at 5.0 mg cm(-2) sulfur), favorable anti-self-discharge capabilities (rest for 72 h at 0.5 C with 2.17%).

Automated summary

A lightweight and multifunctional multi-walled carbon nanotube/sulfur/lithiated sulfonated CNT electrode has been designed to improve the commercialization of lithium-sulfur batteries, showing outstanding performance in sulfur species adsorption, LiPS immobilization, and electrolyte electrocatalysis.