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

MoS2 is a promising anode material for sodium-ion batteries (SIBs) due to its attractive theoretical capacity and low cost. MoS2 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 MoS2 particulates (G-MoS2 ) are synthesized by sulfiding MoO3 in highly concentrated sulfur vapor, which results in epitaxial growth of MoS2 in (002), (100), and (110) lattice planes, with the product consisting of MoS2 particulates of about 300 nm coated with few-layered MoS2 nanosheets. The unique G-MoS2 architecture ensures good dispersion and sufficient distance to accommodate volume expansion during sodiation/desodiation, which effectively prevents stacking of MoS2 , maintaining structural stability. When employed as the working electrode for SIB, G-MoS2 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-MoS2 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 MoS2 .