Lithium-containing composite oxide, cathode active material, positive electrode for lithium ion secondary battery, and lithium ion secondary battery
To provide a lithium-containing composite oxide capable of obtaining a lithium ion secondary battery having a large discharge capacity wherein the deterioration of the discharge voltage due to repetition of a charge and discharge cycle is suppressed, a cathode active material, a positive electrode for a lithium ion secondary battery and a lithium ion secondary battery. A lithium-containing composite oxide, which is represented by the formula I: Li a i Ni b CO c Mn d M e O 2 Formula I, wherein M is at least one member selected from the group consisting of Na, Mg, Ti, Zr, Al, W and Mo, a+b+c+d+e=2, 1.1≤a/(b+c+d+e)≤1.4, 0.2≤b/(b+c+d+e)≤0.5, 0≤c/(b+c+d+e)≤0.25, 0.3≤d/(b+c+d+e)≤0.6, and 0≤e/(b+c+d+e)≤0.1, and wherein the valence of Ni is from 2.15 to 2.45.
1. A lithium-containing composite oxide, having a formula I:
Li a Ni b Co c Mn d M e O 2 (I),
wherein
M is Na, Mg, Ti, Zr, Al, W, and/or Mo,
a+b+c+d+e=2,
1.1≤a/(b+c+d+e)≤1.24,
0.3≤b/(b+c+d+e)≤0.47,
0.1≤c/(b+c+d+e)≤0.25,
0.3≤d/(b+c+d+e)≤0.6, and
0≤e/(b+c+d+e)≤0.1, and
wherein a valence of Ni is in a range of from 2.15 to 2.45, a valence of Li is 1, a valence of Co is 3, a valence of Mn is 4, a valence of Na is 1, a valence of Mg is 2, a valence of Ti is 4, a valence of Zr is 4, a valence of Al is 3, a valence of W is 6, a valence of Mo is 6, and a valence of oxygen (O) is −2, and
wherein, in an X-ray diffraction measurement of the lithium-containing composite oxide, a (020) plane peak assigned to a C2/m space group appears at a 2θ in a range of from 20 to 22°, and a (003) plane peak assigned to an R-3m space group appears at a 2θ in a range of from 18 to 20°.
2. The composite oxide of claim 1 , wherein, in the formula I, M is Ti, Zr, and/or Al.
3. A cathode active material, comprising:
the composite oxide of claim 1 .
4. The material of claim 3 , further comprising:
a coating comprising Zr, Ti, Al, and/or F, and formed on a surface of the lithium-containing composite oxide.
5. The material of claim 3 , comprising a secondary particle comprising a plurality of primary particles and having a D 50 value in a range of from 3 to 10 μm.
6. The material of claim 3 , having a specific surface area in a range of from 0.5 to 5 m 2 /g.
7. A positive electrode suitable for a lithium ion secondary battery, the electrode comprising:
the cathode active material of claim 3 ;
an electrically conductive material; and
a binder.
8. A lithium ion secondary battery, comprising:
the positive electrode of claim 7 ;
a negative electrode; and
a non-aqueous electrolyte.
9. The composite oxide of claim 1 ,
wherein M is Ti, Zr, and/or Al, and
1.1≤a/(b+c+d+e)≤1.24, and
0≤e/(b+c+d+e)≤0.005.
10. A cathode active material, comprising:
the composite oxide of claim 9 .
11. The material of claim 10 , further comprising:
a coating comprising Zr, Ti, Al, and/or F, and formed on a surface of the lithium-containing composite oxide.
12. The material of claim 10 , comprising a secondary particle comprising a plurality of primary particles and having a D 50 value in a range of from 3 to 10 μm.
13. The material of claim 10 , having a specific surface area in a range of from 0.5 to 5 m 2 /g.
14. A positive electrode suitable for a lithium ion secondary battery, the electrode comprising:
the cathode active material of claim 10 ;
an electrically conductive material; and
a binder.
15. A lithium ion secondary battery, comprising:
the positive electrode of claim 14 ;
a negative electrode; and
a non-aqueous electrolyte.
16. The composite oxide of claim 1 , wherein, in the formula I, M comprises Ti.
17. The composite oxide of claim 1 , wherein, in the formula I, M comprises Zr.
18. The composite oxide of claim 1 , wherein, in the formula I, M comprises Al.
19. The composite oxide of claim 1 , wherein, in the formula I, M comprises Mo.
20. The composite oxide of claim 1 , wherein, in the formula I, e is 0.