Comparative Study of Heat Treatment on alpha-MoO3 Nanorods as an Electrode Material for Lithium Ion Batteries

摘要

Uniform alpha-MoO3 nanorods with the width of 100 nm and the length of 2 mu m have been synthesized by facile hydrothermal method. To study the influence of heat treatment on electrochemical properties, the as-synthesized alpha-MoO3 nanorods have been calcined at 400 degrees C for 3 hrs in air, following the characterization of the phase and morphology of alpha-MoO3 nanorods by XRD and SEM. The electrochemical characterization of the alpha-MoO3 nanorods has conducted for the lithium half-cells in the voltage range from 1.5 V to 3.75 V (vs. Li/Li+). The first charge/discharge capacities of as-synthesized and heat treated alpha-MoO3 were 259/297, 274/307 mAh g(-1), respectively. The heat-treated alpha-MoO3 nanorods delivers 307 mAh g(-1) at a rate of 28 mA g(-1) (0.1 C), and it exhibits the high rate performance compared to as-synthesized alpha-MoO3 nanorods. The oxidation states of Mo and O in alpha-MoO3 nanorods have measured by XPS to indicate the strong bonding between Mo and O after heat treatment. Our results present that the oxygen ion filled its vacancy and bonded the molybdenum(V) ion, changed to molybdenum(VI) ion after heat-treatment. It helps to form more stable structure for the heat-treated alpha-MoO3 nanorods, showing the improved electrochemical performances as an electrode material for LIBs.