Enhanced Sodium-Ion Battery Performance by Structural Phase Transition from Two-Dimensional Hexagonal-SnS2 to Orthorhombic-SnS

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• 作者：Tengfei Zhou ; Wei Kong Pang ; Chaofeng Zhang ; Jianping Yang ; Zhixin Chen ; Hua Kun Liu ; Zaiping Guo
• 刊名：ACS Nano
• 出版年：2014
• 出版时间：August 26, 2014
• 年：2014
• 卷：8
• 期：8
• 页码：8323-8333
• 全文大小：747K
• ISSN：1936-086X

文摘

Structural phase transitions can be used to alter the properties of a material without adding any additional elements and are therefore of significant technological value. It was found that the hexagonal-SnS₂ phase can be transformed into the orthorhombic-SnS phase after an annealing step in an argon atmosphere, and the thus transformed SnS shows enhanced sodium-ion storage performance over that of the SnS₂, which is attributed to its structural advantages. Here, we provide the first report on a SnS@graphene architecture for application as a sodium-ion battery anode, which is built from two-dimensional SnS and graphene nanosheets as complementary building blocks. The as-prepared SnS@graphene hybrid nanostructured composite delivers an excellent specific capacity of 940 mAh g^鈥?and impressive rate capability of 492 and 308 mAh g^鈥? after 250 cycles at the current densities of 810 and 7290 mA g^鈥?, respectively. The performance was found to be much better than those of most reported anode materials for Na-ion batteries. On the basis of combined ex situ Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and ex situ X-ray diffraction, the formation mechanism of SnS@graphene and the synergistic Na-storage reactions of SnS in the anode are discussed in detail. The SnS experienced a two-structural-phase transformation mechanism (orthorhombic-SnS to cubic-Sn to orthorhombic-Na_3.75Sn), while the SnS₂ experienced a three-structural-phase transformation mechanism (hexagonal-SnS₂ to tetragonal-Sn to orthorhombic-Na_3.75Sn) during the sodiation process. The lesser structural changes of SnS during the conversion are expected to lead to good structural stability and excellent cycling stability in its sodium-ion battery performance. These results demonstrate that the SnS@graphene architecture offers unique characteristics suitable for high-performance energy storage application.

Keywords:

sodium-ion battery; NIB; SIB; SnS; SnS₂; Sn; graphene; nanosheets; anode