Freestanding 1T MoS2/graphene heterostructures as a highly efficient electrocatalyst for lithium polysulfides in Li–S batteries

Abstract

A novel approach to effectively suppress the “polysulfide shuttle” in Li–S batteries is presented by designing a freestanding, three-dimensional graphene/1T MoS₂ (3DG/TM) heterostructure with highly efficient electrocatalysis properties for lithium polysulfides (LiPSs). The 3DG/TM heterostructure is constructed by few-layered graphene nanosheets sandwiched by hydrophilic, metallic, few-layered 1T MoS₂ nanosheets with abundant active sites. The porous 3D structure and the hydrophilic feature of 1T-MoS₂ are beneficial for electrolyte penetration and Li-ion transfer, and the high conductivities of both graphene and the 1T MoS₂ nanosheets facilitate electron transfer. These merits lead to a high electrocatalytic efficiency for LiPSs due to excellent ion/electron transfer and the presence of sufficient electrocatalytic active sites. Therefore, the cells with 3DG/TM exhibit outstanding electrochemical performance, with a high reversible discharge capacity of 1181 mA h g⁻¹ and a capacity retention of 96.3% after 200 cycles. The electrocatalysis mechanism of LiPSs is further experimentally and theoretically revealed, which provides new insights and opportunities to develop advanced Li–S batteries with highly efficient electrocatalysts for LiPS conversion.