Metal-N4/graphene as an efficient anchoring material for lithium-sulfur batteries: A computational study

Despite their high theoretical capacity, the practical commercialization of lithium-sulfur batteries have continued to face obstacles of low cycle stability and low efficiency, which stem from the dissolution and diffusion of lithium polysulfides intermediates in the electrolyte. Here, by means of comprehensive density functional theory computations, we exploited the potentials of the experimentally available metal-nitrogen/graphene as the anchoring material for high-performance Li-S batteries. Our results revealed that Cr-, Mn-, Fe-, Co-, and Cu-nitrogen/graphenes exhibit optimal interaction with soluble lithium polysulfides due to the synergistic effects between the metal and N atoms, which not only effectively traps the soluble lithium polysulfides to suppress the shuttle effects, but also well keeps their cyclic structures intact. Especially, the electronic properties of metal-nitrogen/graphenes are well preserved, and the computed voltages of discharge processes are larger than those of the well-established nitrogen-doped graphenes. Thus, the metal-nitrogen/graphene could present a kind of quite promising anchoring material for lithium sulfur battery cathodes to suppress the lithium polysulfides shuttle effect.