Oxygen-deficient TiO2 Yolk-shell Spheres for Enhanced Lithium Storage Properties

Anatase TiO2is a promising anode material for lithium-ion batteries(LIBs)owing to its low cost and stability. However, the intrinsically kinetic limits seriously hindered its lithium-ion storage capability. Here we present that anatase TiO2with rich oxygen vacancies can enhance its lithium-ion storage performance. We synthesize anatase TiO2with well-retained hierarchical structure by annealing the H2Ti5O11·3 H2O yolk-shell spheres precursor in nitrogen atmosphere. EPR and XPS data evidence that the oxygen-deficient environment could generate abundant oxygen vacancies in the as-derived anatase TiO2, which leads to improved electron conductivity and reduced charge-transfer resistance. The rich oxygen vacancies and high structural integrity of the hierarchical yolk-shell spheres enable the as-derived anatase TiO2yolk-shell spheres with a high specific capacity of 280 m Ah g-1at 100 m A g-1and 71% of capacity retention after 5000 cycles at 2 Ag-1.