UC Irvine

Uniform TiO2 nanospheres from hollow, core-shell and mesoporous structures have been synthesized using quasi-nano-sized carbonaceous spheres as templates. The TiO2 nanospheres formed after calcination at 400 °C are composed of ∼7 nm nanoparticles and the shells of the hollow TiO2 nanospheres are as thin as a single layer of nanoparticles. The ultrafine nanoparticles endow the hollow and mesoporous TiO2 nanospheres with short lithium ion diffusion paths leading to high discharge specific capacities of 211.9 and 196.0 mA h g-1 at a current rate of 1 C (167.5 mA g-1) after 100 cycles, and especially superior discharge specific capacities of 125.9 and 113.4 mA h g-1 at a high current rate of up to 20 C. The hollow and mesoporous TiO2 nanospheres also show superior cycling stability with long-term discharge capacities of 103.0 and 110.2 mA h g-1, respectively, even after 3000 cycles at a current rate of 20 C.