Lithium titanate powder, active material, and energy storage device using the same
View Patent ↗Provided is a lithium titanate powder for an electrode of an energy storage device, the lithium titanate powder comprising Li 4 Ti 5 O 12 as a main component, wherein, when the volume surface diameter calculated from the specific surface area determined by the BET method is represented as D BET and the crystallite diameter calculated from the half-peak width of the peak of the (111) plane of Li 4 Ti 5 O 12 by the Scherrer equation is represented as D X , D BET is 0.1 to 0.6 μm, D X is greater than 80 nm, and (D BET /D X (μm/μm)) the ratio of D BET to D X is 3 or less. Also provided are an active material including the lithium titanate powder and an energy storage device using the active material.
1. A lithium titanate powder comprising Li 4 Ti 5 O 12 as a main component, wherein,
when a volume surface diameter calculated from a specific surface area determined by a BET method is represented as D BET , and when a crystallite diameter calculated from a half-peak width of a peak for a (111) plane of Li 4 Ti 5 O 12 by a Scherrer equation is represented as D X , D BET is 0.1 to 0.6 μm, D X is larger than 80 nm, a D BET /D X (μm/μm) ratio of D BET to D X is 3 or less, and
a peak of Li 2 TiO 3 is not detected by X-ray diffraction.
2. The lithium titanate powder according to claim 1 , wherein D BET /D X (μm/μm), the ratio of D BET to D X is 2 or less.
3. The lithium titanate powder according to claim 1 , wherein D X is 500 nm or less.
4. The lithium titanate powder according to claim 1 , further comprising M, wherein M is at least one type of metal element selected from the group consisting of a group 2 element, a group 12 element, and a group 13 element.
5. The lithium titanate powder according to claim 4 , wherein the M is at least one type of metal element selected from the group consisting of Mg, Zn, Al, Ga, and In.
6. The lithium titanate powder according to claim 4 , wherein T M /T Ti , an atomic ratio of the M to Ti, for the entire lithium titanate powder measured by the inductively coupled plasma emission spectrometric analysis method is 0.001 to 0.05.
7. The lithium titanate powder according to claim 4 , wherein, in a cross-sectional analysis of a lithium titanate particle using a scanning transmission electron microscope, when an element concentration of the M measured by an energy dispersive X-ray spectroscopy at a 5 nm inner position from a surface of the lithium titanate particle along a straight line drawn vertically to a tangent of the lithium titanate particle surface is D1 (atm %) and when an element concentration of the M measured by an energy dispersive X-ray spectroscopy at a 100 nm inner position from the lithium titanate particle surface along the straight line is D2 (atm %), the D1 and D2 satisfy a formula (I)
D 1> D 2 (I).
8. The lithium titanate powder according to claim 4 , further comprising a fluorine element.
9. The lithium titanate powder according to claim 4 , suitable for use in an electrode of an energy storage device.
10. An active material comprising the lithium titanate powder according to claim 4 .
11. An energy storage device comprising the active material according to claim 10 .
12. A lithium-ion secondary battery comprising the active material according to claim 10 .
13. A hybrid capacitor comprising the active material according to claim 10 .
14. The lithium titanate powder according to claim 1 , further comprising fluorine.
15. The lithium titanate powder according to claim 1 , suitable for use in an electrode of an energy storage device.
16. An active material comprising the lithium titanate powder according to claim 1 .
17. An energy storage device comprising the active material according to claim 16 .
18. A lithium-ion secondary battery comprising the active material according to claim 16 .
19. A hybrid capacitor comprising the active material according to claim 16 .
20. A lithium titanate powder comprising Li 4 Ti 5 O 12 as a main component, wherein,
when a volume surface diameter calculated from a specific surface area determined by a BET method is represented as D BET , and when a crystallite diameter calculated from a half-peak width of a peak for a (111) plane of Li 4 Ti 5 O 12 by a Scherrer equation is represented as D X , D BET is 0.1 to 0.6 μm, D X is larger than 80 nm, and a D BET /D X (μm/μm) ratio of D BET to D X is 3 or less,
the lithium titanate powder further comprises M wherein M is at least one type of metal element selected from the group consisting of a group 2 element, a group 12 element, and a group 13 element, and
in a cross-sectional analysis of a lithium titanate particle using a scanning transmission electron microscope, when an element concentration of the M measured by an energy dispersive X-ray spectroscopy at a 5 nm inner position from a surface of the lithium titanate particle along a straight line drawn vertically to a tangent of the lithium titanate particle surface is D1 (atm %) and when an element concentration of the M measured by an energy dispersive X-ray spectroscopy at a 100 nm inner position from the lithium titanate particle surface along the straight line is D2 (atm %), a ratio D1/D2 of the D1 to the D2 satisfies a formula (II)
D 1/ D 2≧5 (II).