期刊
JOURNAL OF MATERIALS CHEMISTRY A
卷 5, 期 1, 页码 102-112出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/c6ta08039a
关键词
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资金
- National Natural Science Foundation of China [51572060, 51502062]
- China Postdoctoral Science Foundation [2016M590279]
- Fundamental Research Funds for the Central Universities [HIT.BRETIII.201224, 201312]
- Program for Innovation Research of Science in Harbin Institute of Technique (PIRS of HIT) [201506]
- University at Buffalo (SUNY)
- National Science Foundation [CBET-1604392]
Lithium sulfide (Li2S) has drawn special attention as a promising cathode material for emerging energy storage systems due to its high theoretical specific capacity and great compatibility with lithium metal-free anodes. However, Li2S cathodes urgently require a solution to increase their poor electrical conductivity and to suppress the dissolution of long-chain polysulfide (Li2Sn, 4 <= n <= 8) species into electrolyte. To this end, we report a free-standing Al2O3-Li2S-graphene oxide sponge (GS) composite cathode, in which ultrathin Al2O3 films are preferentially coated on Li2S by an atomic layer deposition (ALD) technique. As a result, a combination of high electron conductivity (from GS) and strong binding with Li2Sn (from ultrathin Al2O3 films) was designed for cathodes. The newly developed Al2O3-Li2S-GS cathodes are able to deliver a highly reversible capacity of 736 mA h g(Li2S)(-1) (427 mA h g(cathode)(-1)) at 0.2C, which is much higher than that of corresponding cathodes without Al2O3 (59%). Also, the long-term cycling stability of Al2O3-Li2S-GS cathodes was demonstrated up to 300 cycles at 0.5C with an excellent capacity retention of 88%. In addition, combined with density functional theory calculations, the promotional mechanism of ultrathin Al2O3 films was elucidated using extensive characterization. The ultra-thin Al2O3 film with optimal thickness not only acts as a physical barrier to Li2S nanoparticles, but provides a strong binding interaction to suppress Li2Sn species dissolution.
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