Hollow MoS2 tetrapods for high-performance potassium-ion storage

Abstract

Interfacing two-dimensional materials with three-dimensional world is never a subject that could be bypassed. In this work, MoS2 nanoflakes were purposefully stacked to construct hollow tetrapod structure, which showed great development prospects as a powerful anode material in potassium-ion-battery realm. The accumulation of these tetrapods could build a grand macroscopic interconnected architecture with high porosity, which was propitious to penetration of electrolyte, accessibility of K+ ions and reduction of K+-ion diffusion distance. Moreover, it could provide adequate room for volume changes during potassiation/de-potassiation, and the lattice stress applied on one arm upon cycling could readily transfer to another arm, leading to high structural stability. More than that, the wedge-shaped arms securely anchored the carbon black, so as to make full contact between active material and conductive agent, and thus enhancing electrical conductivity of the whole anode. Furthermore, the hollow arms could also accelerate K+-ion transport and cushion the volume variation to the greatest extent. This delicately-designed structure showed excellent cyclability, enhanced initial Coulombic efficiency and exceptional rate capability during electrochemical processes.