Ternary NiO/RGO-Sn Hybrid Flexible Freestanding Film as Interlayer for Lithium-Sulfur Batteries with Improved Performance

Abstract

A flexible freestanding ternary NiO/RGO-Sn hybrid sandwiched between sulfur cathode and separator, shows chemically trapping effect for sulfur species and polysulfide intermediates for lithium-sulfur (Li-S) battery. In the extraordinary ternary system, the hierarchical NiO hollow structures are tightly wrapped with reduced graphene oxide (RGO), and Sn particles are homogeneously anchored on surface of NiO/RGO composite. This work demonstrated that NiO/RGO-Sn interlayer plays an important role on immobilizing polysulfides, realizing the reactivation of dissolved polysulfides in Li-S batteries. The hierarchical NiO with abundant pores which benefit for polysulfide storage and buffering volume change when acted as interlayers. Simultaneously, RGO with high conductivity serving as upper current collector can significantly improves the electrochemical performance. Besides, NiO and uniformly dispersed Sn particles on the surface of NiO/RGO can effectively prevent the polysulfides from diffusing to the lithium anode by physical and chemical absorption. Immobilizing effect of NiO and Sn for sulfur species and polysulfides is deeply investigated by XPS techniques. The excellent performance of the cell is dominated synergistically by several factors including high electron conductivity of RGO sheets, the abundant pores and the chemical reaction between Sn, NiO species and polysulfides.