MoS2 nanoflowers with expanded interlayers as high-performance anodes for sodium-ion batteries

Abstract

MoS2 nanoflowers with expanded interlayer spacing of the (002) plane were synthesized and used as high-performance anode in Na-ion batteries. By controlling the cut-off voltage to the range of 0.4-3 V, an intercalation mechanism rather than a conversion reaction is taking place. The MoS2 nanoflower electrode shows high discharge capacities of 350 mAh g(-1) at 0.05 A g(-1) , 300 mAh g(-1) at 1 A g(-1) , and 195 mAh g(-1) at 10 A g(-1) . An initial capacity increase with cycling is caused by peeling off MoS2 layers, which produces more active sites for Na(+) storage. The stripping of MoS2 layers occurring in charge/discharge cycling contributes to the enhanced kinetics and low energy barrier for the intercalation of Na(+) ions. The electrochemical reaction is mainly controlled by the capacitive process, which facilitates the high-rate capability. Therefore, MoS2 nanoflowers with expanded interlayers hold promise for rechargeable Na-ion batteries.

Keywords: MoS2; electrochemical exfoliation; expanded layers; pseudocapacitance; sodium-ion batteries.