Three-in-one cathode host based on Nb3O8/graphene superlattice heterostructures for high-performance Li–S batteries

Abstract

Lithium–sulfur batteries have high promise for applications in next-generation energy storage. However, further advances have been hindered by various intractable challenges, particularly three notorious problems: the “shuttle effect”, sluggish kinetics of lithium polysulfide conversion, and nonuniform nucleation of Li₂S. In this study, a three-in-one cathode host based on a superlattice of two-dimensional (2D) materials is designed to tackle these three issues. Alternately restacked Nb₃O₈ nanosheets with Lewis acid surface and reduced graphene oxide (rGO) with high electrical conductivity give rise to a unique superlattice structure without the self-restacking, thereby maximizing the synergistic effect that stems from the inherent advantages of each component. The Nb₃O₈/rGO superlattice cathode host is characterized by its high affinity, excellent catalytic activity, abundance of exposed active sites, and high electrical conductivity, effectively confining lithium polysulfides and reducing the overpotentials for lithium polysulfide conversion and Li₂S nucleation. As a result, high-performance lithium–sulfur batteries were achieved with an initial capacity of 1529 mA h g⁻¹ at 0.1C and a slow capacity decay of 0.064% per cycle at 1C over 1000 cycles. This work provides a novel strategy of heteroassembling 2D nanosheets as a cathode host, opening a promising avenue for advanced lithium–sulfur batteries.