Surfactant-templated TiO2 (anatase):: Characteristic features of lithium insertion electrochemistry in organized nanostructures

Thin layer electrodes (0.2-0.5 mum) of highly organized nanotextured anatase were prepared by hydrolysis of TiCL4 in the presence of poly(alkylene oxide) block copolymer, Pluronic P-123, acting as the structure-directing agent. Electrochemical properties of these layers were studied in KCF3SO3 + propylene carbonate and in LiN(CF3SO2)(2) + ethylene carbonate + dimethoxyethane. The electrodes showed unusually fast capacitive and Li-insertion charging. A most striking effect was the occurrence of two new pairs of peaks in cyclic voltammograms in Li+ containing electrolyte solutions. These, so-called S-peaks, appear in addition to the "ordinary" peaks of Li insertion into anatase. The S-peaks can act as indicators of mesoscopic ordering of the skeleton as they diminish after mechanical or thermal destruction of the organized nanotexture. We suggest that the occurrence of S-peaks is connected to the presence of amorphous TiO2 in the organized skeleton.