Crystallite Size Constraints on Lithium Insertion into Brookite TiO[sub 2]

We demonstrate lithium insertion into brookite TiO 2 in the nanophase regime. The extent of lithium insertion is significantly influenced by the crystallite size. A maximum of 0.95 Li / TiO 2 can be inserted into 10 nm size crystallites and the extent of lithium insertion is low (0.23 Li) in 33 nm crystallites. The reversibility decreases with an increase in crystallite size. The contrasting behavior of brookite and rutile TiO 2 suggests that the structural features of brookite TiO 2 may play an important role in determining Li insertion behavior.