Li1+xMn2O4 synthesized by in-situ lithiation for improving sulfur redox kinetics of Li-S batteries

Abstract

Lithium-sulfur (Li-S) battery is one of the most promising candidates for the next generation energy storage systems. However, the inherent slow redox kinetics of sulfur leads to limited rate performance, low discharge capacity and rapid capacity fading. Herein, the Li1+xMn2O4 material produced by in-situ lithium intercalation of LiMn2O4 before 2.5 V is selected to improve the performances of Li-S batteries. First-principles calculations show that Li1+xMn2O4 can improve electronic conductivity and chemical adsorption. Electrochemical characterizations further confirm that lithiated material provides a fast conversion kinetics for LiPSs and a low barrier of lithium-ion diffusion. As a result, the Li-S battery incorporating Li1+xMn2O4 presents excellent rate performance with a discharge capacity as high as 915 mAh g − 1 at 2 C rate. At the same time, the battery maintains a high reversible capacity of 531 mAh g − 1 after 1000 cycles at 1 C rate, and the average capacity loss per cycle is only 0.047%. This work can improve the redox kinetics of sulfur cathodes and provide a new path for the advancement of high-performance Li-S batteries.