Abstract:Subsphaeroidal MoS2 anode powder material with good electrochemical performance for lithium-ion batteries (LIBs) were synthesized by enhanced hydro-thermal process (EHP) in relatively short reaction time. The ammonium molybdate, thiourea and polyvinyl pyrrolidone (PVP) were used as molybdenum source, sulfur source and soft mold surfactant, respectively. The crystal structure, morphology, element component and valencies of the as-prepared samples were characterized by XRD, SEM, FESEM, TEM, HRTEM and XPS. Galvanostatic charge-discharge, cyclic voltammetry and electrochemical impedance spectroscopy test was utilized to evaluate the electrochemical performance of the batteries assembled by the as prepared powder. The experimental results showed that the as-prepared powder was subsphaeroidal MoS2 particles with an average grain size of about 150nm. After annealing at 500℃ for 2h, there is no significant change in morphology. As anodes for LIBs, subsphaeroidal MoS2 without annealing delivered an relatively high initial discharge capacity of 874.7 mAh/g at a current density of 500 mA/g, which decays in the following cycles. The capacity retention rate after 100 cycles was only 53.3%. As a contrast, electrochemical properties were enhanced for the counterparts after annealing, which exhibited an ultimate (100 cycles) discharge capacity of 571.3 mAh/g and a capacity retention rate of 83.2%. The coulomb efficiency of samples without annealing for the first cycle was only 68.88% and elevated afterwards to reach 100% at the 47th cycle while it is 100% for the annealed specimens in the initial stage and without decay in the following cycles, which indicating an improvement of charge-discharge efficiency. The performance of the annealed specimens enhanced due to the following reasons. The residual molybdenum oxide in the material sublimates during annealing, and lead to some voids appear inside the material, which increase the contact area between the active substance and the electrolyte. Furthmore, the heating treatment improves the crystallinity of the specimens, which can stabilize the crystal structure of MoS2, and inhibit the volume expansion in the discharge/charge process.