Nanocrystalline TiO₂ Electrodes Exhibiting High Storage Capacity and Stability in Rechargeable Lithium Batteries

Abstract

Nanocrystalline TiO₂ films were explored for the first time as electrode material for a rechargeable lithium intercalation cell, i.e., Li/LiCF₃SO₃ + PC/TiO₂. Two kinds of nanocrystalline films, TiO₂ F387 (Degussa) and TiO₂ colloid-240, were investigated. These films exhibited excellent performance renderings them a promising choice for secondary battery applications. At a current density of 0.01 mA/cm², two voltage plateaus at 1.78 and 1.89 V were observed for TiO₂ F387 films during charge and discharge, respectively. The TiO₂ electrode charge capacity per unit weight rose with decreasing current density. The highest capacity, obtained at a current density of 0.005 mA/cm² and a final discharge voltage of 1.4 V, was 265 mAh/g corresponding to a lithium insertion ratio of x = 0.8. Nanocrystalline TiO₂ colloid-240 films showed a similar performance. The cycle life of a TiO₂ colloid-240 cell at a high current density was found to be excellent; a capacity loss lower than 14% has been observed over 100 charge/discharge cycles.