A novel porous C4N4 monolayer as a potential anchoring material for lithium–sulfur battery design

Abstract

Lithium–sulfur (Li–S) batteries have attracted considerable attention due to high theoretical specific energy and environmental friendliness. However, the shuttle of lithium polysulfides (LiPSs) has become a major obstacle for developing Li–S batteries. In this work, we explored a new C₄N₄ monolayer, which could be easily prepared from its bulk form using a similar mechanical exfoliation approach to that of graphene due to its smaller exfoliation energy. The C₄N₄ monolayer could suppress the shuttling of LiPSs and produce significant improvement in the cycling performance of Li–S batteries. Moreover, adsorption calculations revealed that polysulfide captured by C₄N₄ was chemisorbed with a suitable range of adsorption energies from −1.931 to −3.119 eV. Furthermore, excellent surface diffusions of LiPSs on C₄N₄ resulted in a fast charge/discharge rate. Moreover, to improve the electrical conductivity of C₄N₄, graphyne was selected to construct a C₄N₄/graphyne heterostructure. Based on these remarkable results, we conclude that C₄N₄ is a highly promising anchoring material for Li–S batteries. We hope that our studies will inspire more experimental and theoretical studies on exploring the potential of other 2D nanostructures as lithium–sulfur battery hosts.