First-Principle study of lithium polysulfide adsorption on heteroatom doped graphitic carbon nitride for Lithium-Sulfur batteries

The intermediate lithium polysulfide species (LiPSs) suppressing dissolution into liquid electrolyte has been one of the important issues for large-scale commercial applications of Lithium-sulfur batteries (LSBs). Here, we perform periodic density functional theory calculations to reveal the potential of graphitic carbon nitride nanosheet (g-C3N4) and its heteroatoms (B, O, P and S) doped systems, to be used as chemical anchoring materials for LiPSs. From the calculations, the LiPSs are stabilized on g-C3N4 materials via lithium bond interaction between Li of LiPSs and N of g-C3N4. With the introduction of dopant atoms, tuning possibility of the LiPSs adsorption energies is observed. The interaction of LiPSs on B- and P-doped g-C3N4 provide optimum adsorption energies which is appropriate for LSBs anchoring. However, the O- and S-doped g-C3N4 have a weak adsorption which is similar to the pristine one. The anchoring performance of g-C3N4 materials for suppressing LiPSs in dissolving into the electrolytes is also highlighted by comparing their adsorption on g-C3N4 materials and on various electrolytic clusters. The adsorption energies of LiPSs on B- and P-doped g-C3N4 are found to be stronger than those on electrolytes. The electron transfers and van der Waals interaction are found to play significant roles for the LiPSs adsorption. The results provide the fundamental understanding g-C3N4 surface tuning by doping heteroatoms for the suppression materials to reduce the shuttle effect, which will be beneficial for the advanced LSBs development.