Ultrathin anatase TiO₂ nanosheets embedded with TiO₂-B nanodomains for lithium-ion storage: Capacity enhancement by phase boundaries

A new form of TiO₂ microspheres comprised of anatase/TiO₂-B ultrathin composite nanosheets has been synthesized successfully and used as Li-ion storage electrode material. By comparison between samples obtained with different annealing temperatures, it is demonstrated that the anatase/TiO₂-B coherent interfaces may contribute additional lithium storage venues due to a favorable charge separation at the boundary between the two phases. The as-prepared hierarchical nanostructures show capacities of 180 and 110 mAh g^-1 after 1000 cycles at current densities of 3400 and 8500 mA g^-1. The ultrathin nanosheet structure which provides short lithium diffusion length and high electrode/electrolyte contact area also accounts for the high capacity and long-cycle stability. Anatase nanosheets with TiO₂-B nanodomains form microspheres. Due to its ultrathin nanosheet structure and additional anatase/TiO₂-B interface lithium storage, this anode material displays stable capacities of 180 and 110 mAh g^-1 at 3400 and 8500 mA g^-1 after 1000 cycles. The mechanism of Li-ion storage at the boundaries is discussed.