期刊
CHEMISTRY-A EUROPEAN JOURNAL
卷 24, 期 53, 页码 14154-14161出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/chem.201801505
关键词
bifunctional effect; density functional calculations; host materials; Li-S batteries; Mo2C nanorods; nanostructures
资金
- Special fund of key technology research and development projects [20180201097GX, 20180201099GX, 20180201096GX]
- Jilin province science and technology department
- 13th Five-year plan Science and Technology Research of Jilin province
- Key Subject Construction of Physical Chemistry of Northeast Normal University
- National Key R&D Program of China [2016YFB0100500]
The shuttle effect of polysulfide is the primary obstacle in Li-S batteries. Although some effort has been made to suppress the shuttle process, more highly conductive materials with stronger adsorption ability to polysulfides are still in urgent demand. Another important problem is the deteriorating performance of Li-S batteries with prolonged cycling owing to irreversible deposition of lithium sulfide (Li2S). However, a host material for the effective conversion of insoluble Li2S has been elusive up to now. Herein, porous molybdenum carbide nanorods (Mo2C NRs), with high catalytic activity for Li2S and ultrastrong adsorption for polysulfides, are used as a bifunctional host material and incorporated into sulfur cathodes for the first time. The bifunctional Mo2C NRs have the advantage of immobilizing polysulfides over the conventional host, with adsorption energies from -4.89 to -8.20eV for Li2Sx (x=1, 2, 4, 6, and 8). The electrochemical analysis shows that Mo2C NRs, more than an anchor, can activate Li2S by greatly reducing the charging overpotential. Therefore, the irreversible deposition of polysulfides is effectively restrained and the utilization of Li2S is clearly enhanced. The Mo2C NRs-sulfur composites (Mo(2)CNRs-S) cathodes provide a capacity of 1298mAhg(-1) at 0.1C in the Li-S batteries. More importantly, the battery with Mo(2)CNRs-S cathodes exhibits a much lower capacity decay of 0.062% per cycle at 1C over 500 cycles.
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