An advanced MoS2 /carbon anode for high-performance sodium-ion batteries.

Molybdenum disulfide (MoS2 ) is a promising anode for high performance sodium-ion batteries due to high specific capacity, abundance, and low cost. However, poor cycling stability, low rate capability and unclear electrochemical reaction mechanism are the main challenges for MoS2 anode in Na-ion batteries. In this study, molybdenum disulfide/carbon (MoS2 /C) nanospheres are fabricated and used for Na-ion battery anodes. MoS2 /C nanospheres deliver a reversible capacity of 520 mAh g(-1) at 0.1 C and maintain at 400 mAh g(-1) for 300 cycles at a high current density of 1 C, demonstrating the best cycling performance of MoS2 for Na-ion batteries to date. The high capacity is attributed to the short ion and electron diffusion pathway, which enables fast charge transfer and low concentration polarization. The stable cycling performance and high coulombic efficiency (∼100%) of MoS2 /C nanospheres are ascribed to (1) highly reversible conversion reaction of MoS2 during sodiation/desodiation as evidenced by ex-situ X-ray diffraction (XRD) and (2) the formation of a stable solid electrolyte interface (SEI) layer in fluoroethylene carbonate (FEC) based electrolyte as demonstrated by fourier transform infrared spectroscopy (FTIR) measurements.