2D Cu2-xSe@Graphene Multifunctional Interlayer Boosting Polysulfide Rapid Conversion and Uniform Li2S Nucleation for High Performance Li-S Batteries

Abstract Some vital challenges are main obstacles for further development of lithium-sulfur (Li-S) batteries such as low capacity and poor cycle stability resulted from polysulfide shuttling behavior, the physical/chemical entrapment is regarded as an effective method to inhibit and catalyze polysulfides. Herein we design a cross-linked framework of reduced graphene oxide anchored with Cu2-xSe nanoparticles (Cu2-xSe@rGO) by building an electrolyte/Cu2-xSe/graphene triple-phase interface to be a high-efficiency electrocatalyst for Li-S batteries. Imporatnly, this 3D conductive network possesses a large specific surface area with high ion transport capability, meanwhile providing strong physical constraint for efficient adsorption of soluble polysulfides. Further, this triple-phase catalytic interface provides strong chemical adsorption and abundant Cu2-xSe nanoparticle sulfiphilic active sites, effectively inhibiting the dissolution of polysulfides and guaranteeing the efficient polysulfide adsorption catalysis as well as rapidly uniform Li2S nucleation. Consequently, with the Cu2-xSe@rGO separator, a lower capacity decay rate about 0.059% per cycle after 500 cycles at 2 C is obtained. What’s more, with a higher areal sulfur loading of 3.0 mg cm-2, the capacity is still maintained at 805 mAh g-1 over 100 cycles. Therefore, this work will open new avenue to construct 2D transition metal selenide for superior performance Li-S batteries.