The development of high rate capability electrodes for Li‑ion batteries is a priority topic in order to diversify the applicability of this dispositive. High capacity materials usually fail when the charge‑discharge cycle is carried out at high rates, due to scarce electronic conductivity, high volume expansion, low Li‑ion diffusion coefficient in the solid, among others. Combining different materials allows create composites with superior properties than its raw materials, bringing together the best properties of each component in order to enhance its functionality. Particularly, matrixes with high electronic conductivity that allow the efficient transport toward the current collectors, covered or decorated with materials that can efficiently support the Li‑ion insertion‑extraction process, have shown to be an adequate strategy to avoid diminishing the capacity shrink commonly observed at high C rates.

Herein, MWCNT@TiO₂ composites with different MWCNT:TiO2 ratio (1:5, 1:7.5 and 1.:10) were synthesized by controlled hydrolysis of titanium isopropoxide over the MWCNT and finally heat treated at 400 °C during 4 h. The structural properties of the materials were characterized by TEM, Raman spectroscopy, FTIR, XRD and TGA, and the interaction between MWCNT and TiO2 in MWCNT@TiO₂ anodes during the charging‑discharging process was characterized with electrochemical techniques (CV and charge-discharge curves).

The composite materials showed superior performance compared to that obtained with the pristine TiO₂ or MWCNT, before and after the heat treatment. However, before heat treatment (amorphous state) the composite materials exhibited a capacitive-like behavior, and only after the heat treatment (anatase polimorph) the CV and charge-discharge curves showed a clear charge transfer process in which the lithium ion insertion take place at a specific potential. Additionally, the composites in amorphous state (without heat treatment) exhibited similar values of specific capacity for lithium ion storage, contrasting with the behavior of the materials when were heat treated; in this case, varying the MWCNT:TiO₂ ratio from 1:5 to 1:7.5 carried to a complete coverage of the nanotubes, improving the capacity to storage lithium ions. However, a increasing the TiO₂ in the composite to a ratio 1:10 provoked a  detriment in the material behavior due to the thickening of the TiO₂ shell.The improvement in the TiO₂ rate capability and lithium ion storage capacity offered by the MWCNT@TiO₂ composite seems to be related to the increase in the electronic transport, diminishing the charge transfer resistance and depolarizing the Li⁺ ion insertion in the TiO₂.