Fe, N co-doped graphene as a multi-functional anchor material for lithium-sulfur battery

Abstract

Application of lithium-sulfur battery is still hindered by the poor cycling life, rapid capacity decay and severe self-discharge, which are mainly caused by the well-known dissolving and shuttling effects. Thus, a systematic investigation including perfect graphene, nitrogen doped graphene, iron and nitrogen co-doped graphene as anchor materials for sulfur cathodes in lithium sulfur battery are performed, in order to search new chemical functional graphene with good electrocatalysis and shuttling suppression abilities. Our results reveal that iron and nitrogen co-doped graphene monolayer is a good anchoring material, in which the LiSFeN four-membered ring structure ensures the stability of adsorption structure and allows adsorption energy of the adsorption structure to be in the suitable range. The effect of the four-membered ring mainly contributes by the strong binding between Fe and S coming from magnetic catalytic absorption. Moreover, the FeN4@graphene can promote the fully discharge of lithium polysulfides benefiting from the low decomposition energies of Li2S and Li2S2 on its surface and the catalytic effect of 3d electrons of doped iron. PDOS demonstrates essential role of iron in rending FeS bond with strong anchoring. Our research unravels anchor effect of FeN4@graphene in lithium sulfur batteries and provides invaluable theoretical guidance for high-performance lithium sulfur batteries.