Ru Single Atom Dispersed on MoS2/MXene for Enhanced Sulfur Reduction Reaction in Lithium–Sulfur Batteries

The high theoretical energy density (2600 Wh kg−1) and low cost of lithium–sulfur batteries (LSBs) make them an ideal alternative for the next‐generation energy storage system. Nevertheless, severe capacity degradation and low sulfur utilization resulting from shuttle effect hinder their commercialization. Herein, Single‐atom Ru‐doped 1T/2H MoS2 with enriched defects decorates V2C MXene (Ru–MoS2/MXene) produced by a new phase‐engineering strategy employed as sulfur host to promote polysulfide adsorption and conversion reaction kinetics. The Ru single atom‐doped adjusts the chemical environment of the MoS2/MXene to anchor polysulfide and acts as an efficient center to motivate the redox reaction. In addition, the rich defects of the MoS2 and ternary boundary among 1T/2H MoS2 and V2C accelerate the charge transfer and ion movements for the reaction. As expected, the Ru–MoS2/MXene/S cathode‐based cell exhibits a high‐rate capability of 684.3 mAh g−1 at 6 C. After 1000 cycles, the Ru–MoS2/MXene/S cell maintains an excellent cycling stability of 696 mAh g−1 at 2 C with a capacity degradation as low as 0.02% per cycle. Despite a high sulfur loading of 9.5 mg cm−2 and a lean electrolyte‐to‐sulfur ratio of 4.3, the cell achieves a high discharge capacity of 726 mAh g−1. Ru single‐atom doped defect‐rich 1T/2H MoS2/MXene works as an outstanding electrocatalyst to enhance redox kinetics and inhibit the shuttle effects in Lithium–sulfur batteries. The cells with Ru–MoS2/MXene‐based cathode obtain a high initial discharge capacity of 1426 mAh g−1 at a current density of 0.1 C, and can maintain a high‐rate ability of 684.3 mAh g−1 at 6 C. Despite a high sulfur content of 9.5 mg cm−2 and a low electrolyte condition with an electrolyte‐to‐sulfur ratio of 4.3, the cell can still achieve a high specific capacity of 726 mAh g−1.