Understanding the Inhibition of the Shuttle Effect of Sulfides (S ≤ 3) in Lithium–Sulfur Batteries by Heteroatom-Doped Graphene: First-Principles Study
Benjie Gong, Xuedan Song, Yantao Shi, Jianhui Liu, Ce Hao
Abstract
The shuttle effect of lithium–sulfur batteries has always been a focus of scientific research. One research strategy is to use graphene to improve its performance. Theoretical studies have found that heteroatom-modified graphene can effectively anchor lithium polysulfides (LiPSs) and weaken the shuttle effect. In this study, we combine small sulfur molecules with the 10-heteroatom-doped graphene (h-G, where h = N, O, S, P, or B), and the shuttle effect is largely suppressed by preventing the formation of long-chain LiPSs using density functional theory. The deformation charge density and projected density of state verified that the critical interaction between h-G and LiPSs is the interaction of the lithium atom with the benzene ring and the interaction of the lithium atom with the heteroatom. In addition, the effect of solvation on the adsorption of the LiPSs on h-G is studied. Remarkably, in solvent, the binding energies of polysulfides on pyridine, epoxy, and B-doped graphene were still the largest, indicating that they may be the ideal lithium–sulfur battery cathode materials for suppressing the shuttle effect. This study provides key insights into the underlying mechanism by which h-G with small sulfur molecules contributes to the intrinsic shuttle inhibition and traps the polysulfides.