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

Abstract

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.

Understanding the role of lithium bonds in doped graphene nanoribbons as cathode hosts for Li‐S batteries: A first‐principles study

“…The Bader charges of the lithium bond acceptors before and after adsorption are shown in Table 2. It is interesting to note that the acceptor atoms gain electrons after Li 2 S adsorption while the sulfur atom of the polysulfide loses electrons upon adsorption 42 . This change in the Bader charges upon adsorption can be understood as follows: In an isolated Li 2 S molecule, each lithium atom has a valence Bader charge of 0.139e implying that a charge of 0.861e to sulfur in forming an ionic bond.…”

“…It is interesting to note that the acceptor atoms gain electrons after Li 2 S adsorption while the sulfur atom of the polysulfide loses electrons upon adsorption. 42 This change in the Bader charges upon adsorption can be understood as follows: In an isolated Li 2 S molecule, each lithium atom has a valence Bader charge of 0.139e implying that a charge of 0.861e to sulfur in forming an ionic bond. The sulfur atom possesses a negative charge of 7.72e, upon gaining 1.72e from both lithium atoms.…”

First-Principles Investigation of the 1T-HfTe2 Nanosheet for Selective Gas Sensing

“…Further, to understand the nature of the adsorption (i.e., chemisorbtion or physisorbtion) of the different gas molecules, we calculated the chemical adsorption energy and physical vdW adsorption energy separately . The chemical adsorption energy ( E ads chemical ) is calculated without considering the vdW effects, while the physical vdW interaction energy is calculated using the following formula where E ads vdw is the adsorption energy calculated by considering the vdW functional in eq and E ads no vdW is the adsorption energy calculated without considering the vdW functional, which is nothing but the chemical adsorption energy.…”

Understanding the interactions between lithium polysulfides and anchoring materials in advanced lithium–sulfur batteries using density functional theory

“…Covalent bonding between the P atom of carbon nitride phosphorus (CNP) and the S atoms of LiPSs was also confirmed via the PDOS, which showed overlap of the orbitals of P atoms with S atoms around the Fermi level. 71 In some cases, especially for carbon-based materials, 49,69,[72][73][74] the increased electrical conductivity of the anchoring material during the lithiation process is assumed to be due to the reduction of the band gap after LiPSs adsorption. A small band gap would significantly improve the rate performance of LSBs.…”