Preparation of binder-free thin film Li₄Ti₅O ₁₂ anode with an adjustable thickness through anodic TiO₂ nanotubes

Binder-free thickness-controllable Li₄Ti₅O ₁₂ for application in lithium ion batteries was fabricated by the reaction of Li₂CO₃ and anodic nanotubular TiO₂ at 800 C. As the concentration of Li₂CO₃ increased, the thickness of Li₄Ti₅O₁₂ film increased, leading to increase in discharge capacity. The Li₄Ti₅O ₁₂ film prepared at the optimized concentration of Li ₂CO₃ of 3.8 × 10^-6 mol displayed the maximum capacity of 104 μA h cm^-2 at the first cycle, which corresponds to 103 mA h g^-1. We found that excess Li ₂CO₃ led to creation of LiTiO₂ phases in the Li₄Ti₅O₁₂ film, which reduced the discharge capacity. For comparison, a Li₄Ti₅O₁₂ film was prepared by the reaction of Li₂CO₃ on a non-anodized Ti foil. In this case, discharge capacity was dramatically reduced due to the formation of Li₂TiO₃ phases in Li₄Ti ₅O₁₂, which was confirmed by TEM and XRD analysis.