Rational design of hybrid porous nanotubes with robust structure of ultrafine Li4Ti5O12 nanoparticles embedded in bamboo-like CNTs for superior lithium ion storage

Abstract

Robust hybrid porous bamboo-like carbon nanotubes (CNTs), with ultrafine Li₄Ti₅O₁₂ nanoparticles homogeneously embedded, are synthesized by a facile sol–gel process, combined with subsequent heat treatment. The nanohybrids exhibit a reversible capacity as high as 582.4 mA h g⁻¹ at 0.2 A g⁻¹ after 500 cycles, together with excellent rate capability and long-term cycling stability at high current densities. A high discharge capacity of 114.2 mA h g⁻¹ at 5 A g⁻¹ is attained for up to 3000 cycles. The superior electrochemical performance of the nanohybrids is attributed to their structure rather than their composition. Their exceptional electrochemical performance benefits from the high electrical conductivity of the porous carbon matrix, which not only provides continuous three-dimensional electron transportation routes but also simultaneously solves the major problems of pulverization, loss of electrical contact, and particle aggregation of Li₄Ti₅O₁₂ anode. In addition, the highly dispersive, ultrafine Li₄Ti₅O₁₂ nanoparticles greatly shorten the diffusion paths for both electrons and ions. Such a structure not only preserves all the advantages of one-dimensional nanostructures, but also offers potential for a high packing density of electrode materials. Surely, this strategy can be widely extended to other anode materials.