SiO₂/TiO₂ Composite Film for High Capacity and Excellent Cycling Stability in Lithium-Ion Battery Anodes

In this study, partially crystalline anodic TiO₂ with SiO₂ well-distributed througout the entire oxide film is prepared using plasma electrolytic oxidation (PEO) to obtain a high-capacity anode with an excellent cycling stability for Li-ion batteries. The micropore sizes in the anodic film become inhomogeneous as the SiO₂ content is increased from 0% to 25%. The X-ray diffraction peaks show that the formed oxide contains the anatase and rutile phases of TiO₂. In addition, X-ray photoelectron spectroscopy and energy-dispersive X-ray analyses confirm that TiO₂ contains amorphous SiO₂. Anodic oxides of the SiO₂/TiO₂ composite prepared by PEO in 0.2 m H₂SO₄ and 0.4 m Na₂SiO₃ electrolyte deliver the best performance in Li-ion batteries, exhibiting a capacity of 240 µAh cm⁻² at a fairly high current density of 500 µA cm^–2. The composite film shows the typical Li–TiO₂ and Li–SiO₂ redox peaks in the cyclic voltammogram and a corresponding plateau in the galvanostatic charge/discharge curves. The as-prepared SiO₂/TiO₂ composite anode shows at least twice the capacity of other types of binder-free TiO₂ and TiO₂ composites and very stable cycling stability for more than 250 cycles despite the severe mechanical stress.