期刊
ELECTROCHIMICA ACTA
卷 107, 期 -, 页码 78-84出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.electacta.2013.06.009
关键词
Lithium-sulfur battery; Polysulfides; Anatase titania; On-site adsorption; Mixed electric/ionic conductor
资金
- National Natural Science Foundation of China [21173120]
- Natural Science Foundation of Jiangsu Province [BK2011030]
- Jiangsu Innovation Program for Graduate Education [CXZZ13_0158]
- Outstanding Doctoral Dissertation in NUAA [BCXJ13-13]
- Graduate Innovation Center in NUAA [kfjj120209]
The commercialization of lithium-sulfur (Li-S) battery has so far hindered by the low electrochemical utilization and rapid capacity fading of sulfur cathode, which is induced bylaw electric/ionic conductivity, high dissolution of intermediate polysulfides and the volume expansion of sulfur. Herein, we describe an on-site adsorption strategy toward superior stability of sulfur electrode by encapsulating elemental sulfur into mesoporous TiO2 host. Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) measurements obviously indicate that elemental sulfur (S) occupy the mesopores of the TiO2 host, forming a core-shell liked nanostructure. The TiO2/S composite exhibits a superior cycling stability and high Coulombic efficiency during the charge/discharge process. Even at a high current rate of 1 C, the TiO2/S composite shows an initial specific capacity of 650 mAh g(-1) and a specific retention of 89% after 100 cycles. The excellent electrochemical performances are critical related to the significant roles TiO2 host played during the electrochemical reaction. Firstly, the nano-sized TiO2 (similar to 5 nm) traps the polysulfides via chemical bonding interaction to prevent their dissolution and minimize the shuttle effect. More importantly, the in situ formed LixTiO2, acting as a mixed electric/ionic conductor, facilitates easier Li+/e(-) transport. The unique functions of the TiO2 plus its easy availability make the current study conceptually provides new opportunities to reach long-term cycling stability of sulfur cathode using carbon-free hosts. (C) 2013 Elsevier Ltd. All rights reserved.
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