We investigate the point defect chemistry of lithium storage in TiO2 and emphasize its great importance to lithium battery applications. Not only charge carrier concentration but also lithium diffusivity is successfully interpreted in terms of lithium content and activity as well as oxygen stoichiometry. A detailed defect chemical analysis reveals that ionic-electronic defect associations (L-i(center dot) + e' = Li-i(x) and V-o(center dot center dot) + 2e' =V-o(center dot) + e' = V-o(x)) play a significant role in determining the concentration of defects and lithium diffusivity, and hence can have large impact on overall lithium storage performance of oxide based electrode materials. (c) 2012 Elsevier B.V. All rights reserved.