Li-ion Reaction to Improve the Rate Performance of Nanoporous Anatase TiO₂ Anodes

Large initial capacity losses and low tap densities are among the major challenges to the wide-ranging application of Li ion batteries based on anatase titania (TiO₂) anodes. This study reports the root causes of the capacity losses and proposes effective ways to control them. Nanoporous TiO₂ microspheres with a tap density as high as 1.1 g cm⁻³ are successfully prepared by using a spray drying method and a focused study is made of their electrochemical reaction kinetics. According to the results, the capacity losses are ascribed to the irreversible Li-ion interfacial storage capability that arises mainly from the high reactivity between TiO₂ and the electrolyte solution. A new anode material, TiO₂–Li, prepared by reacting TiO₂ with Li ions delivers a 50 % reduction in charge-transfer resistance and a remarkable enhancement of Li-ion diffusion coefficient by almost seven times, as compared to the neat TiO₂ powders. The TiO₂–Li anode presents a much lower initial capacity loss, higher rate performance, and better reversibility.