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

Ti2Nb10O29 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. Ti2Nb10O29-x mesoporous microspheres with a sphere-size range of 0.5-4 mu m are prepared by a one-step solvothermal method followed by thermal treatment in N-2. These Ti2Nb10O29-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. Ti2Nb10O29-x shows a defective shear ReO3 crystal structure with O2- vacancies and an increased unit cell volume, resulting in its increased Li+-ion diffusion coefficient. Besides Ti4+ and Nb5+ ions, Ti2Nb10O29-x comprises Nb4+ ions with unpaired 4d electrons, which significantly increase its electronic conductivity. As a result of these improvements, the Ti2Nb10P29-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). (C) 2017 Elsevier B.V. All rights reserved.