Scalable molten salt strategy synthesis of large-size 2D MoS2(1-x)Se2x alloy for boosting potassium-ion storage performance

Abstract

Owing to the lamellar structure and large theoretical specific capacity, transition metal dichalcogenides (TMDs) are promising anodes for potassium ion batteries (KIBs). However, the development and application of TMDs are greatly confined by the inferior conductivity and structure integrity. Herein, a two-dimensional (2D) MoS2(1-x)Se2x ternary alloy supported by carbon nanosheets (MoS2(1-x)Se2x/C) is designed to boost their electrochemical performance in KIBs. Owing to the unique 2D structure, the assistance of carbon, as well as the synergistic effect of S and Se, the MoS2(1-x)Se2x/C gets many obvious merits as: abundant K+ diffusion path, enhanced structure stability and improved conductivity. Thus, our designed MoS2(1-x)Se2x/C obtains the high reversible capacity (279.93 mAh/g at 0.2 A/g), excellent rate performance and long-cycling capability for KIBs. Even cycling for 500 times at the high current density of 1 A/g, a large reversible capacity of 257.94 mAh/g is kept. Moreover, the energy storage mechanisms of MoS2(1-x)Se2x during potassiation and depotassiation process are revealed. Our work provides a new insight into the modification of TMDs anode for potassium ion batteries.