Hydrothermal synthesis of hexagonal MoO3 and its reversible electrochemical behavior as a cathode for Li-ion batteries

Hexagonal molybdenum trioxide (h-MoO3) nanoparticles with a particle size of several tens of nanometers were prepared from sodium molybdate (Na2MoO4) using hydrothermal synthesis and ultrasonication. The morphology, structure, composition, and chemical states of the nanoparticles were characterized by x-ray diffraction, field-emission scanning electron microscopy, and Fourier transform-infrared spectroscopy. Cyclic voltammetry results showed a strong reduction peak, which indicated a lithium ion insertion/extraction mechanism. The plateau observed in the first discharge curve around 1.8 V was in accordance with the above mechanism, which was also verified by differential capacity measurements. Cycling performance results showed that the capacity retention was up to 90% in the second cycle and that the irreversible capacities decreased with subsequent cycles.