Heterogeneous Structural and Electronic Properties of Binary Mo_xS_y and Ternary M_zMo_xS_y (M= Mn, Zn, Ni; z ≤ 0.5) Chalcogels for Li-S Batteries

Lithium-sulfur batteries present a promising alternative to conventional lithium-ion batteries due to their high theoretical capacity, primarily attributed to their high sulfur content. However, challenges such as polysulfide shuttling and limited recharge cycles, remain critical obstacles. Binary Mo_xS_y-based chalcogels show promising potential to overcome these limitations by reducing sulfur dissolution into the electrolyte through influence of Mo atoms. Incorporating a 3d transition metal such as Mn²⁺, Zn²⁺, and Ni²⁺ can create a synergistic effect with Mo in ternary structures (M_zMo_xS_y, where M= Mn, Zn, Ni; z ≤ 0.5), through the formation of metal-sulfur interactions, which can influence lithium diffusion kinetics and enhance both stability and gravimetric capacity. Here, we develop an atomic-scale computational model based on density functional theory (DFT) and ab initio molecular dynamics (AIMD) to generate amorphous models and characterize the structural properties, demonstrating variations in the heterogeneity of the structures. We then employ the supercell core-hole (SCH) method to evaluate x-ray absorption characteristics. Our approach is validated through comparisons with experimental data such as synchrotron X-ray PDF, XANES, and XPS. These materials offer a promising alternative to sulfur-only electrodes for high capacity in next-generation lithium-sulfur batteries.