Porous CNT@Li4Ti5O12 coaxial nanocables as ultra high power and long life anode materials for lithium ion batteries

Abstract

Porous CNT@Li₄Ti₅O₁₂ core–sheath coaxial nanocables were designed using a sol–gel method combined with a following low temperature reflux process and a short post-annealing in the presence of bamboo-like polymer nanotubes acting as a template and a carbon source. As anodes for lithium ion batteries, coaxial nanocables exhibit a high reversible capacity of 322.5 mA h g⁻¹ at 200 mA g⁻¹ after 200 cycles. They also have excellent rate capability and superior long-term cycling stability at high current density, which could attain a high discharge capacity of 198.7 mA h g⁻¹ at 2000 mA g⁻¹ for up to 2000 cycles. Compared with the Li₄Ti₅O₁₂ nanoparticles, the enhanced electrochemical performance of the CNT@Li₄Ti₅O₁₂ nanocomposites benefits from the shortened Li⁺ diffusion distance, large contact surface area, high conductivity, and good structure stability of the coaxial nanocables, which simultaneously solves the major problems on the loss of electrical contact and the aggregation of particles for Li₄Ti₅O₁₂ anodes. The material with a nanocable structure is a potential candidate for developing advanced electrochemical energy storage systems with high power and long life.