Room‐Temperature Synthesis of High Surface Area Anatase TiO 2 Exhibiting a Complete Lithium Insertion Solid Solution

The synthesis of highly divided anatase TiO 2 nanoparticles displaying 300 m 2 g −1 surface area is achieved by following a two‐step synthetic process at room temperature. The particles exhibit a needle‐like morphology composed of self‐assembled 4 nm nanoparticles. The crystallization process from amorphous TiO 2 .1.6H 2 O to oriented aggregation of anatase TiO 2 proceeds according to a slow solid dehydration process taking place in a large range of pH in deionized water (1 < pH < 12) or alternatively when including a low amount of NH 4 F (aq) in solution. Driven by their high surface area enhancing the chemical/electrochemical reactivity, it is reported in the case of the anatase TiO 2 that a modification in the lithium insertion mechanism is no longer attributable to a two‐phase reaction between the two‐end members Li ε TiO 2 and Li 0.5± α TiO 2 when downsizing the particle size, but instead through a complete solid solution all along the composition range.