Targeted Construction of Amorphous MoSx with an Inherent Chain Molecular Structure for Improved Pseudocapacitive Lithium-Ion Response.
Chemistry
; 25(66): 15173-15181, 2019 Nov 27.
Article
em En
| MEDLINE
| ID: mdl-31544301
ABSTRACT
Owing to low ion/electron conductivity and large volume change, transitional metal dichalcogenides (TMDs) suffer from inferior cycle stability and rate capability when used as the anode of lithium-ion batteries (LIBs). To overcome these disadvantages, amorphous molybdenum sulfide (MoSx ) nanospheres were prepared and coated with an ultrathin carbon layer through a simple one-pot reaction. Combining X-ray photoelectron spectroscopy (XPS) with theoretical calculations, MoSx was confirmed as having a special chain molecular structure with two forms of S bonding (S2- and S2 2- ), the optimal adsorption sites of Li+ were located at S2 2- . As a result, the MoSx electrode exhibits superior cycle and rate capacities compared with crystalline 2H-MoS2 (e.g., delivering a high capacity of 612.4â
mAh g-1 after 500â
cycles at 1â
A g-1 ). This is mainly attributed to more exposed active S2 2- sites for Li storage, more Li+ transfer pathways for improved ion conductivity, and suppressed electrode structure pulverization of MoSx derived from the inherent chain-like molecular structure. Quantitative charge storage analysis further demonstrates the improved pseudocapacitive contribution of amorphous MoSx induced by fast reaction kinetics. Moreover, the morphology contrast after cycling demonstrates the dispersion of active materials is more uniform for MoSx than 2H-MoS2 , suggesting the MoSx can well accommodate the volume stress of the electrode during discharging. Through regulating the molecular structure, this work provides an effective targeted strategy to overcome the intrinsic issues of TMDs for high-performance LIBs.
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Ano de publicação:
2019
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Article