Ti2Nb10O29–x mesoporous microspheres as promising anode materials for high-performance lithium-ion batteries

Ti 2 Nb 10 O 29 has recently been reported as a promising anode material for lithium-ion batteries. However, its poor electronic conductivity and insufficient Li + -ion diffusion coefficient significantly limit its rate capability. To tackle this issue, a strategy combining nanosizing and crystal-structure modification is employed. Ti 2 Nb 10 O 29– x mesoporous microspheres with a sphere-size range of 0.5–4 μm are prepared by a one-step solvothermal method followed by thermal treatment in N 2 . These Ti 2 Nb 10 O 29– x mesoporous microspheres exhibit primary nanoparticles , a large specific surface area (22.9 m 2  g −1 ) and suitable pore sizes, leading to easy electron/Li + -ion transport and good interfacial reactivity. Ti 2 Nb 10 O 29– x shows a defective shear ReO 3 crystal structure with O 2− vacancies and an increased unit cell volume, resulting in its increased Li + -ion diffusion coefficient. Besides Ti 4+ and Nb 5+ ions, Ti 2 Nb 10 O 29– x comprises Nb 4+ ions with unpaired 4 d electrons, which significantly increase its electronic conductivity. As a result of these improvements, the Ti 2 Nb 10 O 29– x mesoporous microspheres reveal superior electrochemical performances in term of large reversible specific capacity (309 mAh g −1 at 0.1 C), outstanding rate capability (235 mAh g −1 at 40 C) and durable cyclic stability (capacity retention of 92.1% over 100 cycles at 10 C).