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

Abstract

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 .

Keywords: batteries; epitaxial growth; molybdenum sulfide; sodium; sulfur.