Facile synthesis of dual-phase lithium titanate nanowires as anode materials for lithium-ion battery

Highlights: • A facile wet corrosion and ion exchange process were investigated. • Li₄Ti₅O₁₂-TiO₂ dual phase nanowire was successfully prepared at low temperature. • The phase compositions significantly affect the electrochemical performance. • Li₄Ti₅O₁₂-TiO₂ nanowires with a phase ratio of 3:7 show superior performance. -- Abstract: A facile method to synthesize dual phase Li₄Ti₅O₁₂-TiO₂ nanowires and their performance as anode material for lithium-ion battery are investigated. Li₄Ti₅O₁₂-TiO₂ nanowires are obtained from titanium nanoparticles by applying the wet corrosion process for the nanostructure formation and subsequent ion exchange processes. Post-heat treatments are adopted to tune the mixed phase composition of the nanowires, which significantly influences the electrochemical performance. The dual phase nanowires-based anode materials with a TiO₂: Li₄Ti₅O₁₂ phase ratio of 7:3 exhibit the highest delithiation capacity of 180 mAh/g and 105 mAh/g at 0.5 C and 5 C, respectively. In addition, it shows a remarkable capacity retention of ~95% after 150 cycles at 5 C, which is a significant improvement compared to previous reports on Li₄Ti₅O₁₂-TiO₂ based anode materials synthesized at low temperatures. This dual phase anode material based on Li₄Ti₅O₁₂-TiO₂ nanowires combines two advantages: i) High aspect ratio nanostructures increase the surface area and shorten the diffusion path of lithium ions and ii) the dual phase accelerates ion/electron migration owing to abundant interfaces/grain boundaries. Consequently, the proposed synthesis route for Li₄Ti₅O₁₂-TiO₂ nanowires provides an effective and highly reproducible approach to fabricate dual phase Li₄Ti₅O₁₂-TiO₂ nanowires as anode materials for lithium ion batteries.