Enhanced electrochemical performance of TiO₂ by Ti³⁺ doping using a facile solvothermal method as anode materials for lithium-ion batteries

A facile method has been developed to synthesize Ti³⁺-doped TiO₂ nanoparticles as high-performance anode materials for Li-ion batteries. After reducing some Ti⁴⁺ ions to Ti³⁺ ions with zinc powders in TiCl₄ solution, Ti³⁺-doped TiO ₂ was synthesized by solvothermal methode. The obtained Ti ³⁺-doped TiO₂ nanoparticles are relatively uniform and better dispersed with an average size of 30 nm. Great improvement of the electrochemical performance was obtained by Ti³⁺-doping comparing with the pure TiO₂. The Ti³⁺-doped TiO₂ nanoparticles prepared at the Zn:Ti molar ratio of 4% are able to deliver a reversible capacity of 202.1 mAh g^-1 at a current density of 100 mA g^-1 and exhibit superior high-rate discharge/charge capability and cycling stability at the current density up to 3000 mA g^-1 in a half cell configuration. The improved reversible capacity and rate capability could be ascribed to the presence of Ti³⁺, which improves the electrical conductivity and reduces the charge transfer resistance of the TiO₂ electrode.