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| Left: Charge-discharge curves of the CoS2 hollow spheres. Upper right: XRD profiles of the CoS2 hollow spheres. Lower right: SEM images of the spheres. Credit: ACS, Wang et al. Click to enlarge. |
Researchers at Nankai University (China) have synthesized uniform hollow spheres of CoS2 that display low charge and discharge
potential plateaus, high discharge capacity (1,210 mAh g-1), and good cycle
performance in lithium-ion storage and retrieval, indicating that the material may be a promising candidate for lithium-ion battery anodes.
The CoS2 material might also be applied in areas such as catalysis, semiconductors,
alkaline rechargeable batteries, and others, the team noted in a paper published in the ACS Journal of Physical Chemistry C. The simple and facile solvothermal synthesis method can also be used for the preparation of other metal sulfides, such as MnS, FeS, CuS, and so on.
Cobalt sulfides of different stoichiometric composition (e.g., CoS, CoS2, and Co9S8) are of interest for application in a number of fields. In addition, recent research has shown that a hollow and porous structure is promising for reversible Li+ intercalation with high stability.
However, to the best of our
knowledge, there are no reports about the solvothermal preparation
and electrochemical property of CoS2 hollow spheres. Herein,
we report a facile and efficient solvothermal route to synthesize
uniform hollow spheres of CoS2. Absolute ethanol (EtOH) in the
reaction acted not only as a solvent but also as a weak reducing
agent. Sulfur powder is used as a sulfur source.—Wang et al.
Wang et al.’s key strategy is using sulfur powder as the sulfur source, while absolute ethanol (EtOH) serves as the solvent and reducing agent simultaneously.
SEM images showed that the resulting hollow spheres are about 2-3&icro;m in diameter and 300 nm in shell thickness.
In the first chagre-dischagre process, a Li-ion anode using the hollow spheres displayed a charge capacity of 900 mAh g-1 and a high discharge capacity of about 1,210 mAh g-1. The team attributed the large irreversible capacity in the first cycle to
the formation of solid-electrolyte interphase (SEI) film onto
the surface of the electrode materials.
Resources
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Qinghong Wang, Lifang Jiao, Yan Han, Hongmei Du, Wenxiu Peng, Qingna Huan, Dawei Song, Yuchang Si, Yijing Wang, and Huatang Yuan (2011) CoS2 Hollow Spheres: Fabrication and Their Application in Lithium-Ion Batteries. J. Phys. Chem. C doi: 10.1021/jp111626a