Effective Lithium Polysulfides Anchoring on Vanadium Disulfide Facets for Lithium-Sulfur Batteries – A Computational Study

Abstract

The commercialization of Li-S batteries is hindered by the shuttle effects of lithium polysulfides (LiPS) and the sluggish reaction kinetics. Hence, effectively trapping and promoting the conversion rates of LiPSs is of prime importance1. However, the fundamental kinetics of the electrocatalytic charging and discharging of Li-S batteries and the underlying mechanism have not been sufficiently explored yet.2 Therefore, by taking the 2D transition metal sulfide, VS2 as a model, we conducted a systematic investigation using density functional theory to study the ability of dominant exposed crystal planes of VS2 to trap LiPSs from leaching into electrolyte solvents and to act as an electrocatalyst to increase the Sulfur Reduction Reaction (SRR) kinetics3. To reflect a realistic environment of a battery, the effect of electrolyte solvents on the electrocatalytic activity was further investigated. Our calculations show that VS2 has moderate binding energy toward LiPSs which inhibits LiPS from leaching into electrolytes while fulfilling the key prerequisite to act as an electrocatalyst simultaneously.4 At the discharge, the conversion of S8 to the long chain Li2S8 was facile with a lower energy barrier while the rest of the reactions were sluggish explaining the accumulation of LiPSs. Further, the VS2 (001) facet exhibits excellent electrocatalytic activity for the SRR and Li2S decomposition reaction at charging compared to other dominant crystal planes, which significantly lowers the energy barriers of LiPS conversion during the charging and discharging process, ensuring high-rate performance and longer cycle life4. References Manthiram, A., Fu, Y., Chung, S.-H., Zu, C., & Su, Y.-S. (2014). Rechargeable Lithium–Sulfur Batteries. Chemical Reviews, 114(23), 11751–11787.Abraham, A. M., Thiel, K., Shakouri, M., Xiao, Q., Paterson, A., Schwenzel, J., Ponnurangam, S., & Thangadurai, V. (2022). Ultrahigh Sulfur Loading Tolerant Cathode Architecture with Extended Cycle Life for High Energy Density Lithium–Sulfur Batteries. Advanced Energy Materials, 2201494.Abraham, A. M., Boteju, T., Ponnurangam, S., & Thangadurai, V. (2022). A global design principle for polysulfide electrocatalysis in lithium–sulfur batteries—A computational perspective. Battery Energy, 20220003.Boteju, T., Abraham, A. M., Ponnurangam, S., & Thangadurai, V. (2023). Theoretical Study on the Role of Solvents in Lithium Polysulfide Anchoring on Vanadium Disulfide Facets for Lithium–Sulfur Batteries. The Journal of Physical Chemistry C.