Two-dimensional biphenylene: a promising anchoring material for lithium-sulfur batteries

Trapping lithium polysulfides (LiPSs) on a material effectively suppresses the shuttle effect and enhances the cycling stability of Li-S batteries. For the first time, we advocate a recently synthesized two-dimensional material, biphenylene, as an anchoring material for the lithium-sulfur battery. The density functional theory calculations show that LiPSs bind with pristine biphenylene insubstantially with binding energy ranging from -0.21 eV to -1.22 eV. However, defect engineering through a single C atom vacancy significantly improves the binding strength (binding energy in the range -1.07 to -4.11 eV). The Bader analysis reveals that LiPSs and S8 clusters donate the charge (ranging from -0.05 e to -1.12 e) to the biphenylene sheet. The binding energy of LiPSs with electrolytes is smaller than those with the defective biphenylene sheet, which provides its potential as an anchoring material. Compared with other reported two-dimensional materials such as graphene, MXenes, and phosphorene, the biphenylene sheet exhibits higher binding energies with the polysulfides. Our study deepens the fundamental understanding and shows that the biphenylene sheet is an excellent anchoring material for lithium-sulfur batteries for suppressing the shuttle effect because of its superior conductivity, porosity, and strong anchoring ability.

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