LITHIUM TITANATE POWDER FOR ELECTRODE OF ENERGY STORAGE DEVICE, ACTIVE MATERIAL, AND ENERGY STORAGE DEVICE USING THE SAME

摘要

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 Li4Ti5O12 as a main component, and wherein, when a volume surface diameter calculated from specific surface area determined by the BET method is DBET and a crystallite diameter calculated from half-peak width of (111) plane of Li4Ti5O12 by the Scherrer equation is DX, DBET is 0.1 to 0.6 μm; DX is larger than 80 nm; DBET/DX (μm/μm), ratio of DBET to DX, 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.;D1/D2≧5  (I);0.02≦D1/Dti≦0.4  (II)

主权项

1: A lithium titanate powder, comprising Li4Ti5O12 as a main component, wherein,
when a volume surface diameter calculated from specific surface area determined by the BET method is represented as DBET, and when a crystallite diameter calculated from a half-peak width of the peak for (111) plane of Li4Ti5O12 by the Scherrer equation is represented as DX,
DBET is 0.1 to 0.6 μm,DX is larger than 80 nm,DBET/DX (μm/μm), ratio of DBET to DX, is 3 or less, the lithium titanate powder comprises M, wherein M is at least one type of metal element selected from the group consisting of Mg, Zn, Al, Ga, and In, and in a cross-sectional analysis of a lithium titanate particle using a scanning transmission electron microscope, when atomic concentration of the M and atomic concentration of titanium measured by energy dispersive X-ray spectroscopy at the 5 nm inner position from a surface of the lithium titanate particle along a straight line drawn vertically to tangent of the lithium titanate particle surface are D1 (atm %) and Dti (atm %) respectively, and when atomic concentration of the M at 100 nm inner position from the surface of the lithium titanate particle along the straight line is D2 (atm %), following formulas (I) and (II) are satisfied:
D1/D2≧5  (I)0.02≦D1/Dti≦0.4  (II).