Synthesis of Grain-like MoS2 for High-Performance Sodium-Ion Batteries

Graphical Letting steam do the work : A grain-like MoS 2 is synthesized by sulfiding MoO 3 using a highly concentrated sulfur vapor. MoS 2 grows epitaxially on three lattice planes, giving rise to particulate MoS 2 coated with MoS 2 nanosheet. Such an architecture gives rise to good dispersity and sufficient distance between neighbors to accommodate the volume change associated with sodiation/desodiation and exhibits a high and stable capacity when used in a sodium-ion battery. MoS 2 is a promising anode material for sodium-ion batteries (SIBs) due to its attractive theoretical capacity and low cost. MoS 2 generally presents a sheet-like structure based on its (002) lattice plane; however, such a structure tends to result in agglomeration and stacking of the sheets that cannot accommodate volume expansion, resulting in poor cyclability. Herein, grain-like MoS 2 particulates (G-MoS 2 ) are synthesized by sulfiding MoO 3 in highly concentrated sulfur vapor, which results in epitaxial growth of MoS 2 in (002), (100), and (110) lattice planes, with the product consisting of MoS 2 particulates of about 300 nm coated with few-layered MoS 2 nanosheets. The unique G-MoS 2 architecture ensures good dispersion and sufficient distance to accommodate volume expansion during sodiation/desodiation, which effectively prevents stacking of MoS 2 , maintaining structural stability. When employed as the working electrode for SIB, G-MoS 2 delivers a high reversible capacity of 324 mAh g −1 at 0.5 A g −1 , retaining 312 mAh g −1 over 300 cycles with an average coulombic efficiency of 99.8 %. Even when G-MoS 2 is cycled at a high current density (2.0 A g −1 ), the retained capacity is 175 mAh g −1 after 400 cycles. Comparison with literature reveals that these capacities are among the more promising reversible values reported for pure MoS 2 .