Positive electrode active material and battery including same
View Patent ↗A positive electrode active material according to the present disclosure includes a lithium composite oxide that contains first particles having a crystal structure belonging to space group R-3m and second particles having a crystal structure belonging to space group C2/m. The crystal structure of the second particles has a larger amount of cation mixing than the crystal structure of the first particles. The second particles have a smaller particle size than the first particles. Mathematical Formula 0.05≤integrated intensity ratio I (18°-20°) /I (43°-46°) ≤0.99 is satisfied. The integrated intensity ratio I (18°-20°) /I (43°-46°) is a ratio of the integrated intensity I (18°-20°) to the integrated intensity I (43°-46°) . The integrated intensity I (A°-B°) is the integrated intensity of a maximum peak present in the range of angle of diffraction 2θ greater than or equal to A° and less than or equal to B° in the X-ray diffraction pattern of the lithium composite oxide.
1. A positive electrode active material comprising:
a lithium composite oxide,
wherein the lithium composite oxide contains
first particles having a crystal structure belonging to space group R-3m, and
second particles having a crystal structure belonging to space group C2/m,
the crystal structure of the second particles has a larger amount of cation mixing than the crystal structure of the first particles,
the second particles have a smaller particle size than the first particles, and
the following mathematical formula (I) is satisfied:
0.05≤integrated intensity ratio I (18°-20°) /I (43°-46°) ≤0.99 (I),
where the integrated intensity ratio I (18°-20°) /I (43°-46°) is a ratio of an integrated intensity I (18°-20°) to an integrated intensity I (43°-46°) ,
the integrated intensity I (18°-20°) is an integrated intensity of a first peak that is a maximum peak present in a range of angle of diffraction 2° greater than or equal to 43° and less than or equal to 46° in an X-ray diffraction pattern of the lithium composite oxide, and
the integrated intensity I (18°-20°) is an integrated intensity of a second peak that is a maximum peak present in a range of angle of diffraction 2θ greater than or equal to 18° and less than or equal to 20° in the X-ray diffraction pattern of the lithium composite oxide.
2. The positive electrode active material according to claim 1 , wherein the integrated intensity ratio I (18°-20°) /I (43°-46°) is greater than or equal to 0.62 and less than or equal to 0.99.
3. The positive electrode active material according to claim 1 , wherein the first particles have a particle size greater than or equal to 30 nanometers.
4. The positive electrode active material according to claim 1 , wherein the lithium composite oxide contains at least one selected from the group consisting of F, Cl, N, and S.
5. The positive electrode active material according to claim 4 , wherein the lithium composite oxide contains F.
6. The positive electrode active material according to claim 1 , wherein the lithium composite oxide further contains Mn.
7. The positive electrode active material according to claim 1 , wherein the lithium composite oxide has an average composition represented by the following composition formula (I):
Li x Me y O α Q β (I)
where Me is at least one selected from the group consisting of Mn, Co, Ni, Fe, Cu, V, Nb, Mo, Ti, Cr, Zr, Zn, Na, K, Ca, Mg, Pt, Au, Ag, Ru, W, B, Si, P, and Al,
Q is at least one selected from the group consisting of F, Cl, N, and S, and
the following four mathematical formulas are satisfied:
1.05≤ x≤ 1.5,
0.6≤ y≤ 1.0,
1.2≤α≤2.0, and
0≤β≤0.8.
8. The positive electrode active material according to claim 7 , wherein Me includes at least one selected from the group consisting of Mn, Co, Ni, Fe, Cu, V, Ti, Cr, and Zn.
9. The positive electrode active material according to claim 7 , wherein Me includes at least one selected from the group consisting of Mn, Co, Ni, Al, and Mg.
10. The positive electrode active material according to claim 8 , wherein the Me includes Mn.
11. The positive electrode active material according to claim 10 , wherein a molar ratio of Mn to Me is greater than or equal to 0.6.
12. The positive electrode active material according to claim 7 , wherein Q includes F.
13. The positive electrode active material according to claim 7 , wherein the following two mathematical formulas are satisfied:
1.166≤ x≤ 1.4, and
0.67≤ y≤ 1.0.
14. The positive electrode active material according to claim 7 , wherein the following two mathematical formulas are satisfied:
1.33≤α<2.0, and
0≤β≤0.67.
15. The positive electrode active material according to claim 14 , wherein the following two mathematical formulas are satisfied:
1.33≤α≤1.9, and
0.1≤β≤0.67.
16. The positive electrode active material according to claim 1 , wherein the lithium composite oxide is contained as a main component in the positive electrode active material.
17. A battery comprising:
a positive electrode containing the positive electrode active material according to claim 1 ;
a negative electrode; and
an electrolyte.
18. The battery according to claim 17 , wherein
the negative electrode contains at least one selected from the group consisting of
(i) a negative electrode active material capable of intercalating and deintercalating lithium ions, and
(ii) a material from which lithium metal dissolves into the electrolyte during discharging and on which the lithium metal deposits during charging, and
the electrolyte is a non-aqueous electrolyte solution.
19. The battery according to claim 17 , wherein
the negative electrode contains at least one selected from the group consisting of
(i) a negative electrode active material capable of intercalating and deintercalating lithium ions, and
(ii) a material from which lithium metal dissolves into the electrolyte during discharging and on which the lithium metal deposits during charging, and
the electrolyte is a solid electrolyte.