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

KGaA, Weinheim 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.