Abstract
As a popular strategy, interlayer expansion significantly improves the Li-ion diffusion kinetics in the MoS2 host, while the large interlayer spacing weakens the van der Waals force between MoS2 monolayers, thus harming its structural stability. Here, an oxygen-incorporated MoS2 (O-MoS2)/graphene composite as a self-supported intercalation host of Li-ion is prepared.
The composite delivers a specific capacity of 80 mAh g(-1) in only 36 s at a mass loading of 1 mg cm(-2), and it can be cycled 3000 times (over 91% capacity retention) with a 5 mg cm(-2) loading at 2 A g(-1). The O-MoS2 exhibits a dominant 1T phase with an expanded layer spacing of 10.15 angstrom, leading to better Li-ion intercalation kinetics compared with pristine MoS2.
Furthermore, ex situ X-ray diffraction tests indicate that O-MoS2 sustains a stable structure in cycling compared with the gradual collapse of pristine MoS2, which suffers from excessive lattice breathing. Density functional theory calculations suggest that the MoOx(OH)(y) pillars in O-MoS2 interlayers not only expand the layer spacing, but also tense the MoS2 layers to avoid exfoliation in cycling.
Therefore, the O-MoS2 shows a pseudolayered structure, leading to remarkable durability besides the outstanding rate capability as a Li-ion intercalation host.