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

Abstract

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(-1)and impressive rate capability of 492 and 308 mAh g(-1) after 250 cycles at the current densities of 810 and 7290 mA g(-1), 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-Na3.75Sn), while the SnS2 experienced a three-structural-phase transformation mechanism (hexagonal-SnS2 to tetragonal-Sn to orthorhombic-Na3.75Sn) 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.

Booming Development of Group IV–VI Semiconductors: Fresh Blood of 2D Family

“…Most employed solvothermal methods for synthesizing GIVMCs can summarized by the following procedure: Sn‐halogenides (Cl used mostly) + varied chalcogenide precursors, as shown in Figure 3 a 97, 117, 119, 140, 141, 144, 145, 146, 147. Usually the selection of chalcogenides and the combination of ligands can play crucial roles in determining the morphology, sizes, yield and crystal phases of the as‐synthesis products.…”

“…Consequently, the as‐synthesized products are employed to fabricate metal–semiconductor–metal (MSM) device to study the optoelectronic properties and demonstrate the potential use in optoelectronics and photovoltaics. Interestingly, Guo and co‐workers117 have performed the subsequent structural phase transition process in argon from SnS 2 to SnS structures. As demonstrated in Figure 3b, the formation of this phase transition may depend on the S depletion in the annealed process.…”

“…Then, dissociation process is promoted by the S depletion and high temperatures. This route is on the basis of the inconsistent sublimation of SnS 2 , leading to a direct transition from SnS 2 to SnS 117, 148. What is more, this route paves a new way to alter the properties of a product without any additional elements through structural phase transition, which may enlighten the applications in electronics and optoelectroncis.…”

“…After annealing, SnS 2 dissociation occurs, and S depletion and high temperatures promote dissociation processes. Reproduced with permission 117. 2014, American Chemical Society.…”

“…In general, GIVMCs have been classified into two groups according to their chemical compositions: MX (SiC,89 SiS,90 GeS,91, 92 GeSe,93, 94, 95, 96 SnS,97, 98, 99 SnSe,100, 101, 102, 103, 104, 105, 106, 107, 108 SnTe,109, 110) and MX 2 (GeS 2 ,111 GeSe 2 ,112, 113, 114, 115 SnS 2 ,72, 116, 117, 118 SnSe 2 73, 119, 120, 121, 122, 123, 124, 125). In this part, some typical GIVMCs are presented in Table 1 .…”