TiO2/MoO2 nanocomposite as anode materials for high power Li-ion batteries with exceptional capacity

Abstract

Nanoparticles of molybdenum(IV) oxide (MoO2) and a TiO2/MoO2 nanocomposite were synthesised via a continuous hydrothermal synthesis process. Both powders were analysed using XRD, XPS, TEM, and BET and evaluated as active materials in anodes for Li-ion half-cells. Cyclic voltammetry and galvanostatic charge/discharge measurements were carried out in the potential window of 0.1 to 3.0 V vs. Li/Li+. Specific capacities of ca. 350 mAh g-1 were obtained for both materials at low specific currents (0.1 A g-1); TiO2/MoO2 composite electrodes showed superior rate behaviour & stability under cycling (compared to MoO2), with stable specific capacities of ca. 265 mAh g-1 at a specific current of 0.5 A g-1 and ca. 150 mAh g-1 after 350 cycles at a specific current of 2.5 A g-1. The improved performance of the composite material, compared to MoO2, was attributed to a smaller particle size, improved stability to volume changes (during cycling), and lower charge transfer resistance during cycling. Li-ion hybrid electrochemical capacitors using TiO2/MoO2 composite anodes and activated carbon (AC) cathodes were evaluated and showed excellent performance with an energy density of 44 Wh kg-1 at a power density of 600 W kg-1.