Three-Dimensional Porous TiNb₂O₇/CNT-KB Composite Microspheres as Lithium-Ion Battery Anode Material

Nano-TiNb₂O₇/multiwalled carbon nanotube and ketjen black (TiNb₂O₇/CNT-KB) composite microspheres with porous three-dimensional (3D) hierarchical heterostructure are fabricated by spray drying and solvothermal method. This composite material exhibits a high reversible charge specific capacity of 327.8 mAh g⁻¹ at the current rate of 0.1 C and 151.1 mAh g⁻¹ at 20 C rate. When it is cycled at a high current rate of 5 C for 1000 cycles, the charge capacity is dropped from the maximum value of 220.8 mAh g⁻¹ (6^th cycle) to the end value of 145.4 mAh g⁻¹, with capacity retention of 65.9 %. The TiNb₂O₇/CNT-KB composite material demonstrates much superior electrochemical performance over the bare TiNb₂O₇ material, and this result should be attributed to its particular porous 3D hierarchical structure, which possesses enhanced electrical conductivity as well as the ability for accommodating volume change and preventing particle aggregation of the electrode active material during the discharge and charge cycles.