Transition Metal Compounds Family for Li-S Batteries: The DFT-Guide for Suppressing Polysulfides Shuttle

Lithium-sulfur batteries (LSBs) are considered as one of the best candidates for the next generation of high-energy-density storage devices owing to their superior theoretical energy density, high specific capacity, and sufficient sulfur reservoirs. However, the shuttle effect of soluble polysulfides and sluggish LiPSs redox kinetics restrict the further application of LSBs. The polysulfides shuttle effect can be efficiently alleviated and LiPSs conversion kinetics be accelerated by designing optimal transition metal compounds (TMCs) as multifunctional catalyst materials. Herein, recent advances about TMCs in LSBs are systematically summarized and analyzed. First of all, the intrinsic structural characteristics of TMCs and relevant application on their works to the adsorption energies studies are described in detail. Second, the bonding manners and structural properties are analyzed by density functional theory (DFT)-guided calculations, focusing on the adsorption and diffusion behavior between TMCs and LiPSs. Furthermore, the mechanism of LiPSs redox reaction conversion is studied from kinetics aspects, thus developing the continuous dynamic analysis on "adsorption-diffusion-conversion" toward LiPSs. Eventually, this study particularly highlights the importance of modification engineering and provides a forward-looking overview for its further application prospects by introduction of the previous advanced studies in LSBs.