Nano-TiNb2O7/carbon nanotubes composite anode for enhanced lithium-ion storage

Although with a large capacity, TiNb 2 O 7 as an anode material of lithium-ion batteries suffers from a poor rate capability. To solve this challenge, nano-TiNb 2 O 7 and its carbon nanotube (CNT) nanocomposites were prepared by direct hydrolysis of TiNb 2 O 7 /CNTs suspension followed by calcination in air and N 2 , respectively. The TiNb 2 O 7 nanoparticles in the composites have a Ti 2 Nb 10 O 29 -type crystal structure with O 2− vacancies and lower-valence cations, leading to improved Li + -ion diffusion coefficient and increased electronic conductivity in TiNb 2 O 7 . The evenly distributed CNTs have good contact with the TiNb 2 O 7 particles, thereby reducing their particle sizes and improving the electrical conduction. As a result of these improvements, the nanocomposites present outstanding electrochemical performances. For example, it delivers a large reversible capacity (346 mAh g −1 at 0.1 C) and a prominent rate capability (still 163 mAh g −1 at the ultra-large current rate of 30 C). Exceptional cyclic stability is also demonstrated with over 100 cycles at 10 C with large capacity retention of 97.6%. These results reveal that the nano-TiNb 2 O 7 /CNTs composites can be a promising anode material for lithium-ion batteries of electric vehicles.