Targeted Construction of Amorphous MoSx with an Inherent Chain Molecular Structure for Improved Pseudocapacitive Lithium-Ion Response |
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Authors: | Dr Yao-Yao Wang Dr Hong-Hong Fan Zhi-Wei Wang Wan-Yue Diao Dr Chao-Ying Fan Prof Xing-Long Wu Prof Jing-Ping Zhang |
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Institution: | 1. Northeast Normal University, Faculty of Chemistry, National & Local United Engineering Laboratory for Power Batteries, Changchun, Jilin, 130024 P. R. China
These authors contributed equally to this work.;2. Northeast Normal University, Faculty of Chemistry, National & Local United Engineering Laboratory for Power Batteries, Changchun, Jilin, 130024 P. R. China;3. Faculty of Chemistry, Northeast Normal University, Key Laboratory for UV Light-Emitting Materials and Technology Changchun, Jilin, 130024 P. R. China |
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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 S22?), the optimal adsorption sites of Li+ were located at S22?. As a result, the MoSx electrode exhibits superior cycle and rate capacities compared with crystalline 2H-MoS2 (e.g., delivering a high capacity of 612.4 mAh g?1 after 500 cycles at 1 A g?1). This is mainly attributed to more exposed active S22? 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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Keywords: | amorphous MoSx capacitive characteristics chain-like molecular structure density functional calculations full batteries |
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