Facile kinetics of Li-ion intake causes superior rate capability in multiwalled carbon nanotube@TiO₂ nanocomposite battery anodes

Nanotechnology produces hybrids with superior properties than its individual constituents. Here MWCNT@TiO₂ composites have been synthesized by controlled hydrolysis of titanium isopropoxide over MWCNT, to be incorporated into Li-ion battery electrodes. Outstanding rate capability of the coated nanotubes is observed in comparison to pristine TiO₂. Specific storage capacity as high as 250 mAh g^-1 is achieved for the nanocomposite electrode which doubles that encountered for TiO₂-based anodes. The mechanism explaining the enhancement in power performance has been revealed by means of electrochemical impedance methods. Although both pristine TiO₂ and MWCNT@TiO₂ would potentially exhibit comparable specific capacity, the charge transfer resistance for the latter is reduced by a factor 10, implying a key role of MWCNTs to favor the interfacial Li ⁺ ion intake from the electrolyte. MWCNT efficiently provides electrons to the nanostructure through the Ti-C bond which assists the Li ⁺ ion incorporation. These findings provide access to the detailed lithiation kinetics of a broad class of nanocomposites for battery applications.