Lithium insertion properties of mesoporous nanocrystalline TiO₂ and TiO₂–V₂O₅ microspheres prepared by non-hydrolytic sol–gel

Mesoporous nanocrystalline TiO₂ and TiO₂–V₂O₅ microspheres were prepared by non-hydrolytic sol–gel from TiCl₄, VOCl₃, and ⁱPr₂O at 110 °C without any solvent or additives. The samples were characterized by elemental analysis, X-ray diffraction, Raman spectroscopy, scanning electron microscopy, nitrogen physisorption, and impedance measurements. At low vanadium loadings, only TiO₂ anatase was detected, and V₂O₅ scherbinaite was also detected at high vanadium loadings. The texture of the samples depended on the V loading, but all the samples appeared built of primary nanoparticles (≈10–20 nm in size) that aggregate to form mesoporous micron-sized spheres. The lithium insertion properties of these materials were evaluated by galvanostatic measurements taken using coin-type cells, in view of their application as electrode for rechargeable Li-ion batteries. The mesoporous TiO₂ microspheres showed good performances, with a specific reversible capacity of 145 and 128 mAh g⁻¹ at C/2 and C, respectively (C = 335.6 mA g⁻¹), good coulombic efficiency, and a moderate capacity fade (6 %) from the 2nd to the 20th cycle at C/20. Although the addition of V effectively increased the electronic conductivity of the powders, the specific reversible capacity and cycling performances of the TiO₂–V₂O₅ samples were only minimally improved for a 5 at% V loading and were lower at higher V loading.