Black anatase titania enabling ultra high cycling rates for rechargeable lithium batteries

Abstract

In this work we report the synthesis and the characterization of black anatase TiO2. We show that this material displays a nanostructured architecture, with an electro-conducting trivalent Ti. The presence of trivalent Ti in this structure narrows the inherent high band gap energy to a semiconductor level, reaching a value as low as 1.8 eV, resulting in the very high electrical conductivity of 8 × 10−2 S cm−1. These extraordinary electro-conducting physical properties ensure an ultra fast Li+ insertion into and extraction from the host structure of anatase TiO2 making it a unique, high rate electrode, delivering at a 100 C-rate (20 A g−1) a discharge capacity of 127 mA h (g-TiO2)−1 with approximately 86% retention during 100 charge–discharge cycles at 25 °C and approximately 84% retention at −20 °C.