Understanding the Anchoring Effect of Two-Dimensional Layered Materials for Lithium-Sulfur Batteries

Although the rechargeable lithium-sulfur battery system has attracted significant attention due to its high theoretical specific energy, its implementation has been impeded by multiple challenges, especially the dissolution of intermediate lithium polysulfide (Li₂S_n) species into the electrolyte. Introducing anchoring materials, which can induce strong binding interaction with Li₂S_n species, has been demonstrated as an effective way to overcome this problem and achieve long-term cycling stability and high-rate performance. The interaction between Li₂S_n species and anchoring materials should be studied at the atomic level in order to understand the mechanism behind the anchoring effect and to identify ideal anchoring materials to further improve the performance of Li-S batteries. Using first-principles approach with van der Waals interaction included, we systematically investigate the adsorption of Li₂S_n species on various two-dimensional layered materials (oxides, sulfides, and chlorides) and study the detailed interaction and electronic structure, including binding strength, configuration distortion, and charge transfer. We gain insight into how van der Waals interaction and chemical binding contribute to the adsorption of Li₂S_n species for anchoring materials with strong, medium, and weak interactions. We understand why the anchoring materials can avoid the detachment of Li₂S as in carbon substrate, and we discover that too strong binding strength can cause decomposition of Li₂S_n species. (Graph Presented).