Thgraphene with High Polysulfide Anchoring Ability and Catalytic Performance for Advanced Na-S Batteries: A First-Principles Study.

The sodium-sulfur (Na-S) batteries, with advantages such as high energy density, high specific capacity, and low cost, have attracted significant attention in the field of rechargeable batteries in recent years. However, their practical application still faces many challenges. In this study, we employ first-principles calculations to investigate the performance of a 2D carbon allotrope, thgraphene, as an anchoring material in Na-S batteries. Our studies reveal that thgraphene possesses the modest adsorption strength (0.70-1.75 eV) toward S/NaS species, which is beneficial for inhibiting the dissolution and shuttle effect of sodium polysulfides. Furthermore, thgraphene demonstrates excellent bifunctional catalytic activity, displaying reduced Gibbs free energy barrier (0.58 eV) for sulfur reduction reaction (SRR) and lower NaS decomposition barrier (0.76 eV); thus, it would greatly enhance the electrode reaction kinetics during the charge/discharge processes. Additionally, we find that applying certain strain can not only maintain the adsorption strength of S/NaS species but also improve the sulfur reaction activity. These theoretical findings provide an avenue for the potential application of thgraphene in Na-S batteries.