A Pseudolayered MoS2 as Li-Ion Intercalation Host with Enhanced Rate Capability and Durability.

TL;DR: 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, leading to remarkable durability besides the outstanding rate capability as a Li-ion intercalation host.

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 A, 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.