TiNbxO2+2.5x (x=2, 5, 6)/C hybrid nanotubes with enhanced kinetics for high-performance lithium anodes

Abstract

Hybrid nanostructure is proposed to settle the sluggish kinetic problems of titanium niobates. Herein, 1D porous TiNbxO2+2.5x (x = 2, 5, 6)/C hybrid nanotubes are controllably constructed through a sol-gel method. As anodes of lithium-ion batteries (LIBs), these TiNbxO2+2.5x (x = 2, 5, 6)/C hybrid nanotubes show favorable electrochemical performances, especially the highly hybrid nanotubes (TiNb6O17/C) illustrate a high specific capacity of 438.2 mAh g−1 after 750 cycles (0.4 A g−1), and possess a competitive kinetic diffusion ability compared with other Nb-based anodes. Additionally, ex situ XRD analysis also confirms its structural stability and reversibility. As an extension, the TiNb6O17/C hybrid nanotubes deliver a full cell performance of 159.6 mAh g−1 after 100 cycles at 0.2 A g−1. Such favorable performances of TiNb6O17/C further testify the rationality of hybrid nanostructure. The product with highly conductive network guarantees the kinetic transmission of ions and electrons, and the confinement of the CNTs matrix on the nanoparticles effectively retrains their volume change, while ensuring the structural stability of hybrid nanotubes. Consequently, TiNb6O17/C hybrid nanotubes with high electrochemical performances and stable structure are proved to be promising anode material for future energy application.