Recently, the research group led by Professor Wang Guoyong from the College of Materials Science and Engineering, Jilin University has made new advances in lithium–sulfur batteries. The corresponding research paper, entitled Oxygen Dopants in MoS₂ Catalysts as Dual Anchors for a Lithium Polysulfide Chain to Accelerate Conversion to Solid Li₂S: A Strategy to Mitigate the Shuttle Effect in Li–S Batteries, has been published in Nano Letters.
Sulfur delivers an ultrahigh theoretical specific capacity, nearly ten times that of commercial cathode materials for lithium-ion batteries, making it a highly promising candidate for rechargeable batteries. Nevertheless, lithium polysulfides are generated as intermediate products during the redox reaction between sulfur and lithium ions. Their orbital structures bear strong similarities to electrolyte molecules, which renders lithium polysulfides highly soluble in electrolytes. This solubility causes active sulfur species to detach from the cathode and dissolve into the electrolyte, ultimately triggering severe rapid capacity decay of batteries.
In this work, an oxygen doping modulation strategy for molybdenum disulfide (MoS₂) is proposed. By precisely engineering the optimal surface oxygen doping configuration, the spacing between doped oxygen atoms matches the dual lithium sites along lithium polysulfide chains to achieve targeted adsorption. This design not only guides the oriented arrangement of S–S bonds on the catalyst surface but also firmly anchors long-chain polysulfide molecules, enlarging the contact area between polysulfides and catalysts and accelerating the decomposition of lithium polysulfides. Meanwhile, this strategy effectively restrains the diffusion of polysulfides in electrolytes and drastically alleviates the notorious shuttle effect.
Figure 1. Schematic illustration of polysulfide adsorption processes on different sample surfaces.
Negatively charged oxygen dopants are distributed with uniform intervals, enabling simultaneous adsorption of the two positively charged lithium terminals on lithium polysulfide chains onto the electrode surface. This configuration sustains electrical conduction between lithium polysulfides and the electrode, preventing polysulfide dissolution and migration toward the counter electrode where parasitic side reactions take place. Furthermore, catalytically active MoS₂ accelerates the conversion kinetics of lithium polysulfides. Benefiting from the above advantages, the as-assembled Li–S battery delivers an initial capacity of 1410.4 mAh g⁻¹ at 0.2 C with a capacity retention of 62.7% after 100 cycles. At a high current density of 2 C, the electrode achieves an initial capacity of 880.3 mAh g⁻¹, with an ultralow capacity decay of only 0.094% per cycle over 400 cycles.
Figure 2. Electrochemical performance of Li–S batteries assembled with Mo(S–O)₂ materials.
Li Chunlin, a doctoral student from the College of Materials Science and Engineering, Jilin University, is the first author of this paper. Professor Wang Guoyong from the same college serves as the corresponding author. This research was generously supported by the National Key Research and Development Program of China, the Key Research and Development Program for Science and Technology of Changchun City, and the State Key Laboratory of Mechanics and Control of Aerospace Structures at Nanjing University of Aeronautics and Astronautics.
