3D graphene framework supported Li2S coated with ultra-thin Al2O3 films: binder-free cathodes for high-performance lithium sulfur batteries. Issue 1 (27th October 2016)

• Record Type: Journal Article
• Authors: Chen, Yan; Lu, Songtao; Zhou, Jia; Wu, Xiaohong; Qin, Wei; Ogoke, Ogechi; Wu, Gang
• Is Part Of: Journal of materials chemistry. Volume 5:Issue 1(2017)
• Page Start: 102
• Page End: 112
• Publication Date: 2016-10-27
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c6ta08039a
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : A newly developed Al2 O3 –Li2 S–GS cathode with Al2 O3 ultra-thin layers preferentially coated on Li2 S by ALD can deliver a significantly improved cycling and rate performance for Li–S batteries. Abstract : Lithium sulfide (Li2 S) 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, Li2 S cathodes urgently require a solution to increase their poor electrical conductivity and to suppress the dissolution of long-chain polysulfide (Li2 S n, 4 ≤ n ≤ 8) species into electrolyte. To this end, we report a free-standing Al2 O3 –Li2 S–graphene oxide sponge (GS) composite cathode, in which ultrathin Al2 O3 films are preferentially coated on Li2 S by an atomic layer deposition (ALD) technique. As a result, a combination of high electron conductivity (from GS) and strong binding with Li2 S n (from ultrathin Al2 O3 films) was designed for cathodes. The newly developed Al2 O3 –Li2 S–GS cathodes are able to deliver a highly reversible capacity of 736 mA h gLi2 S −1 (427 mA h gcathode −1 ) at 0.2C, which is much higher than that of corresponding cathodes without Al2 O3 (59%). Also, the long-term cycling stability of Al2 O3 –Li2 S–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 Al2 O3 films was elucidated using extensive characterization. The ultra-thin Al2 O3 film with optimal thickness not only acts as a physical barrier to Li2 S nanoparticles, but provides a strong binding interaction to suppress Li2 S n species dissolution.