Boron-phosphide monolayer as a potential anchoring material for lithium-sulfur batteries: A first-principles study

Abstract

In recent years, lithium-sulfur (LiS) batteries have attracted tremendous attention as a promising candidate for the next generation recharged battery because of the high theoretical capacity and theoretical specific energy density. However, the severe shuttle effect and poor conductivity of polysulfides greatly hinder the practical application of LiS batteries. In this study, we have employed the first-principles calculations to propose a promising anchoring material of boron-phosphide (BP) monolayer for LiS batteries. The anchoring behaviors and electronic properties of lithium polysulfides on the BP monolayer have been investigated. The results verify that the BP monolayer can be regarded as a moderate anchoring material because the adsorption energy of the polysulfide species on the BP monolayer is in the range of 0.57–2.85 eV. Such a moderate anchoring material is suggested to be the best choice for battery electrode. By analyzing the components of van der Waals, electrostatic and chemical interactions, the complicated anchoring mechanisms are explored. Furthermore, the adsorption of lithium polysulfides can reduce the band gap of BP monolayer, exhibiting enhanced performance of electronic conductivity. Our results of the good anchoring performance and the enhanced electronic conductivity suggest that the BP monolayer has great promise as a cathode anchoring material for LiS batteries, which could inspire more experimental and theoretical studies to explore and develop the potential of other 2D sheets in energy storage systems.