Robust hollow TiO₂spheres for lithium/sodium ion batteries with excellent cycling stability and rate capability

We report a facile solvothermal synthesis of hollow TiO2 nanospheres using phenolic resin nanospheres as templates under magnetic stirring conditions, followed by annealing. The as-prepared hollow TiO2 nanospheres show an inner diameter of ∼400 nm, a shell thickness of ∼45 nm, and a high specific surface area of 33.8 m2 g-1. When used as anode materials for lithium-ion batteries and sodium-ion batteries, the hollow TiO2 demonstrates excellent cycling stability and rate capability, delivering high lithium storage capacities of 178/138 mA h g-1 at 0.2/1.0 A g-1 after 200/1000 cycles, and high sodium storage capacities of 213/177/115 mA h g-1 after 200/1000/4000 cycles at 0.2/1.0/5.0 A g-1. The outstanding electrochemical performance is related to the robust structural stability of the hollow nanostructured TiO2, which can be expected as a promising anode material for next generation alkali metal ion batteries.