Graphdiyne-Based Monolayers as Promising Anchoring Materials for Lithium-Sulfur Batteries: A Theoretical Study

High energy density, low cost, and environmental friendliness are required for modern energy-storage technologies. The anchoring performance of newly fabricated porous triphenylene-graphdiyne (TPGDY), boron-graphdiyne (BGDY), and nitrogen-graphdiyne (NDGY-C18N6, NGDY-C24N4, and NGDY-C36N6) monolayers are studied by employing density functional theory (DFT). It is found that the porous graphdiyne-based materials offer more space to accommodate lithium polysulfides with moderate adsorption energies and the anchoring performance changes with substrate and the size of Li2Sn molecules: BGDY has a strong chemical interaction with lithium polysulfides due to the large charge transfer as compared to others. The chemical interaction dominates in anchoring species Li2Sn with small size (n = 1, 2), whereas vdW interaction dominates for S8 and larger size Li2Sn (n = 6, 8) species. Furthermore, anchoring lithium polysulfides reduces the band gaps of the graphdiyne-based materials and enhances the electronic conductivity. These intriguing features suggest that graphdiyne-based porous 2D structures are promising anchoring materials for lithium-sulfur batteries.