One-Pot Hydrothermal Synthesis and Electrochemical Performance of Subspheroidal Core–Shell Structure MoS2/C Composite as Anode Material for Lithium-Ion Batteries

Abstract

Molybdenum disulfide (MoS2) is a promising anode material for lithium-ion batteries (LIBs) due to its distinctive graphene-like structure and high specific capacity. However, its commercial application is hindered by the severe volume expansion during lithiation/delithiation and poor conductivity. In this paper, we report a facile one-pot enhanced hydrothermal synthesis strategy to prepare high-performance MoS2/C composite materials. The results indicate that the as-prepared MoS2/C composite is a subspheroidal core–shell structure material, with uniform coating, good particle dispersion, and an average grain size of approximately 80 nm. The morphology of the composite remained unchanged even after annealing at 500 °C for 2 h. The addition of glucose can accelerate the nucleation and growth of MoS2, and higher hydrothermal temperatures can improve the product yield. The addition of PVP has little effect on the yield, but significantly reduces the particle size. The XPS analysis reveals that the MoO3 may be generated as an intermediate product during the hydrothermal process. The electrochemical test results show that the unannealed MoS2/C samples exhibit discharge-specific capacities of 705.2 mAh·g−1 and 625.7 mAh·g−1 after the first cycle and the 100th cycle, respectively, at a current density of 500 mA·g−1, with a capacity retention rate of 88.7%. In contrast, the specific capacity of the MoS2/C specimens after annealing at 500 °C for 2 h shows a tendency to decrease and then slowly increase during the cycles, and the discharge specific capacity is 582.3 mAh·g−1 after the 100th cycle, which is lower than that of the unheated sample. The impedance analysis reveals that the lithium-ion diffusion coefficient of the MoS2/C material without calcination is 2.11 × 10−18 cm·s−2, which is superior to that of the annealed MoS2/C and pristine MoS2 samples. This characteristic is favorable for lithiation/delithiation during the charge/discharge process.