Freestanding 1T MoS ₂ /graphene heterostructures as a highly efficient electrocatalyst for lithium polysulfides in Li-S batteries

A novel approach to effectively suppress the "polysulfide shuttle" in Li-S batteries is presented by designing a freestanding, three-dimensional graphene/1T MoS ₂ (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 MoS ₂ nanosheets with abundant active sites. The porous 3D structure and the hydrophilic feature of 1T-MoS ₂ are beneficial for electrolyte penetration and Li-ion transfer, and the high conductivities of both graphene and the 1T MoS ₂ 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.