Active material, nonaqueous electrolyte battery, battery pack and vehicle
According to one embodiment, there is provided an active material. The active material includes particles of a Na-containing niobium titanium composite oxide having an orthorhombic crystal structure. An intensity ratio I 1 /I 2 is within a range of 0.12≤I 1 /I 2 ≤0.25 in an X-ray diffraction pattern of the active material, according to X-ray diffraction measurement using a Cu-Kα ray. I 1 is a peak intensity of a peak P 1 that is present within a range where 2θ is 27° to 28° in the X-ray diffraction pattern of the active material. I 2 is a peak intensity of a peak P 2 that is present within a range where 2θ is 23° to 24° in the X-ray diffraction pattern of the active material.
1. An active material comprising particles of a Na-containing niobium titanium composite oxide having an orthorhombic crystal structure,
wherein an intensity ratio I 1 /I 2 is within a range of 0.12≤I 1 /I 2 ≤0.25 in an X-ray diffraction pattern of the active material, according to X-ray diffraction measurement using a Cu-Kα ray, I 1 is a peak intensity of a peak P 1 that is present within a range where 2θ is 27° to 28° in the X-ray diffraction pattern of the active material, and I 2 is a peak intensity of a peak P 2 that is present within a range where 2θ is 23° to 24° in the X-ray diffraction pattern of the active material, and
wherein the Na-containing niobium titanium composite oxide is represented by the following formula:
Li 2+v Na 2−w M1 x Ti 6-y-z Nb y M2 z O 14+δ ,
wherein 0≤v≤4, 0.1≤w≤1, 0≤x<2, 0<y<6, 0≤z<3, and −0.5≤δ≤0.5,
the M1 is at least one metal element selected from the group consisting of Cs, K, Sr, Ba, and Ca, and
the M2 is at least one metal element selected from the group consisting of Sn, V, Ta, Mo, W, Fe, Co, and Mn.
2. The active material according to claim 1 , wherein the intensity ratio I 1 /I 2 is within a range of 0.14≤I 1 /I 2 ≤0.2.
3. The active material according to claim 1 , wherein the intensity ratio I 1 /I 2 is within a range of 0.16≤I 1 /I 2 ≤0.18.
4. The active material according to claim 1 , a value of y is within a range of 0.1≤y≤1.
5. The active material according to claim 1 , wherein at least one element selected from the group consisting of Mg, Al, Zr, and Bi is present on a surface of the particles of the Na-containing niobium titanium composite oxide.
6. A nonaqueous electrolyte battery comprising:
a negative electrode comprising the active material according to claim 1 ;
a positive electrode; and
a nonaqueous electrolyte.
7. The nonaqueous electrolyte battery according to claim 6 , wherein the positive electrode comprises at least one selected from the group consisting of a lithium cobalt composite oxide, a lithium nickel cobalt manganese composite oxide, a spinel-type lithium manganese composite oxide, and an olivine-type lithium manganese iron composite phosphate.
8. A battery pack comprising the nonaqueous electrolyte battery according to claim 6 .
9. The battery pack according to claim 8 , further comprising:
an external power distribution terminal; and
a protective circuit.
10. A battery pack comprising nonaqueous electrolyte batteries each according to claim 6 , wherein the nonaqueous electrolyte batteries are electrically connected in series, in parallel, or in combination of series and parallel.
11. A vehicle comprising the battery pack according to claim 8 .
12. The vehicle according to claim 11 , wherein the battery pack is configured to recover a regenerative energy of a power of the vehicle.