Transition metal atom catalysts suppress the shuttle effect: a first-principles study

Abstract

The theoretical energy density of lithium-sulfur batteries (LSBs) reaches as high as 2600 mA·h·g⁻¹. However, challenges such as poor sulfur conductivity, the polysulfide shuttle effect, and sluggish Li₂S(the product of sulfur reduction reaction) oxidation kinetics have significantly hindered their practical development. Building on first-principles calculations, this study provides an in-depth analysis of the anchoring and catalytic performance of single-atom catalysts embedded in two-dimensional GeC monolayers (TM-GeC), investigating their potential as sulfur composite materials for LSBs. Through calculations of their structural stability, adsorption capacity, conductivity, charge transfer and Li₂S oxidation kinetics, it was determined that Fe-GeC and Co-GeC exhibit outstanding properties as potential sulfur host materials, anchoring lithium polysulfides (LiPSs) effectively. The material also maintains exceptional electrical conductivity, both prior to and following the adsorption of LiPSs. This property allows the entire system to exhibit metallic behavior and substantially lowers the free energy associated with the sulfur reduction reaction. In addition, the adsorption and catalytic mechanisms of Fe-GeC and Co-GeC have been elucidated, providing novel perspectives for the design of sulfur composite materials that possess superior anchoring capacity and catalytic performance.