Optimized Ti Doping in CoMoO₄ Nanorods as Anodes with Enhanced Electrochemical Performance for Lithium-Ion Batteries

In this work, we have optimized titanium doping (Ti 4+ ) into the CoMoO 4 nanorod anode material to improve its intrinsic behavior, such as low electrical conductivity, poor cycling stability, and large volume expansion/contraction during (de) lithiation for lithium-ion battery applications. Among all the doping concentrations of 5, 20, and 40 wt %, the CoMoO 4 nanorod anode with 20 wt % doping exhibits high reversible capacity, better cycling stability, and superior rate capability. It is believed that Ti 4+ doping generates two extra electrons corresponding to cationic (Mo 6+ ) vacancy and leads to anionic (O 2– ) vacancy in the CoMoO 4 crystal lattice. In addition, though XPS results demonstrate the partial reduction of Mo 6+ to Mo 5+ species after doping, it is believed that one extra electron in the d-orbital may also help to alleviate the electronic conductivity and enhance the diffusion rate of Li + ions. As per the structural refinement results, it is found that the 5 wt % Ti-doped sample forms a solid solution, whereas 20 and 40 wt % Ti-doped samples show excess Ti, which is present in the form of TiO 2 as an additional phase, resulting in the generation of the CoMoO 4 @TiO 2 nanocomposite. The superior electrochemical performances of the 20 wt % Ti-doped CoMoO 4 anode can be accounted for the high mobility of Li + ions due to the optimum doping concentration, proper defects, and synergistic effect of TiO 2 nanoparticles, which are stuck to the surface of the CoMoO 4 nanorods, resulting in improved electronic conductivity and excellent cycling stability of the host material.