| abstract |
Provided is a lithium titanate powder for an electrode of an energy storage device, an active material containing the same, and an energy storage device using the active material. The lithium titanate powder comprises Li 4 Ti 5 O 12 as a main component, and wherein, when a volume surface diameter calculated from specific surface area determined by the BET method is D BET and a crystallite diameter calculated from half-peak width of (111) plane of Li 4 Ti 5 O 12 by the Scherrer equation is D x , D BET is 0.1 to 0.6 µm; D X is larger than 80 nm; D BET /D X (µm/µm), ratio of D BET to D X , is 3 or less; M (wherein M is at least one type of metal element selected from a group consisting of Mg, Zn, Al, Ga, and In) is contained; and when atomic concentrations of the M and titanium at 5 nm inner positions from a surface of a lithium titanate particle are D1 (atm%) and Dti (atm%) respectively, and when atomic concentration of the M at 100 nm inner position from the lithium titanate particle surface is D2 (atm%), following formulas (I) and (II) are satisfied. D 1 / D 2 ‰¥ 5 0.02 ‰¤ D 1 / Dti ‰¤ 0.4 |