Lithium nickel manganese oxide composite material, preparation method thereof and lithium ion battery
Provided are a lithium nickel manganese oxide composite material, a preparation method thereof and a lithium ion battery. The preparation method includes: a first calcining process is performed on a nano-oxide and a nickel-manganese precursor, to obtain an oxide-coated nickel-manganese precursor; and a second calcining process is performed on the precursor and a lithium source material, to obtain the lithium nickel manganese oxide, and a temperature of the first calcining process is lower than the second calcining process. A a lower temperature, the nano-oxide may be melted, a denser nano-oxide coating layer is formed on the surface of the precursor, so the oxide-coated nickel-manganese precursor is obtained. At a higher temperature, the nano-oxide, a nickel-manganese material and a lithium element may be more deeply combined. A problem that the nano-oxide layer is easy to fall off is solved, and cycle performance of the lithium nickel manganese oxide is greatly improved.
1. A preparation method for a lithium nickel manganese oxide composite material, the preparation method comprises:
performing a first calcining process on a nano-oxide and a nickel-manganese precursor, to obtain an oxide-coated nickel-manganese precursor; wherein the nickel-manganese precursor is represented by Ni x Mn y (OH) 2 , 0.50≤x≤0.92, 0.50≤y≤0.8; the nano-oxide is selected from two or more in a group consisting of an aluminum oxide, a zirconium oxide, a titanium oxide, a niobium oxide, a tungsten oxide, a lanthanum oxide and a molybdenum oxide; and
performing a second calcining process on the oxide-coated nickel-manganese precursor and a lithium source material, to obtain the lithium nickel manganese oxide composite material, and a temperature of the first calcining process is lower than a temperature of the second calcining process.
2. The preparation method according to claim 1 , wherein before performing the first calcining process, the preparation method further comprises:
performing a first mixing step on the nano-oxide and the nickel-manganese precursor, to obtain a first mixture;
wherein the first mixing step process is mixed for 10-20 min at a rotation speed of 2000-3000 rpm.
3. The preparation method according to claim 2 , wherein the first calcining process is a temperature programmed process;
the first calcining process comprises:
in an oxygen atmosphere, increasing a temperature of a first calcining reaction to a first target temperature at a rate of 3-5° C./min, and a holding time is 4-6 h, wherein the first target temperature is 300-600° C.; and
decreasing the temperature of the first calcining reaction to a room temperature, to obtain the oxide-coated nickel-manganese precursor.
4. The preparation method according to claim 3 , wherein the nano-oxide is a mixture of zirconium oxide and aluminum oxide, a weight ratio of the zirconium oxide, the aluminum oxide and the nickel-manganese precursor is (0.001-0.003):(0.001-0.003):1.
5. The preparation method according to claim 4 , wherein before performing the second calcining process, the preparation method further comprises:
performing a second mixing step on the oxide-coated nickel-manganese precursor and the lithium source material, to obtain a second mixture;
wherein the second mixing step process is mixed for 10-20 min at a rotation speed of 2000-3000 rpm.
6. The preparation method according to claim 5 , wherein the second calcining process is a temperature programmed process;
the second calcining process comprises:
in an oxygen atmosphere, increasing a temperature of a second calcining reaction to a second target temperature at a rate of 3-5° C./min, and holding time is 8-12 h, wherein the second target temperature is 910-950° C.; and
decreasing the temperature of the second calcining reaction to a room temperature, to obtain the lithium nickel manganese oxide composite material.
7. The preparation method according to claim 3 , wherein before performing the second calcining process, the preparation method further comprises:
performing a second mixing step on the oxide-coated nickel-manganese precursor and the lithium source material, to obtain a second mixture;
wherein the second mixing step process is mixed for 10-20 min at a rotation speed of 2000-3000 rpm.
8. The preparation method according to claim 2 , wherein the nano-oxide is a mixture of zirconium oxide and aluminum oxide, a weight ratio of the zirconium oxide, the aluminum oxide and the nickel-manganese precursor is (0.001-0.003):(0.001-0.003):1.
9. The preparation method according to claim 2 , wherein before performing the second calcining process, the preparation method further comprises:
performing a second mixing step on the oxide-coated nickel-manganese precursor and the lithium source material, to obtain a second mixture;
wherein the second mixing step process is mixed for 10-20 min at a rotation speed of 2000-3000 rpm.
10. The preparation method according to claim 1 , wherein before performing the second calcining process, the preparation method further comprises:
performing a second mixing step on the oxide-coated nickel-manganese precursor and the lithium source material, to obtain a second mixture;
wherein the second mixing step process is mixed for 10-20 min at a rotation speed of 2000-3000 rpm.
11. The preparation method according to claim 10 , wherein the second calcining process is a temperature programmed process;
the second calcining process comprises:
in an oxygen atmosphere, increasing a temperature of a second calcining reaction to a second target temperature at a rate of 3-5° C./min, and holding time is 8-12 h, wherein the second target temperature is 910-950° C.; and
decreasing the temperature of the second calcining reaction to a room temperature, to obtain the lithium nickel manganese oxide composite material.
12. The preparation method according to claim 10 , wherein a ratio of a mole number of a Li element in the lithium source material to a sum of mole numbers of a Ni element and a Mn element in the oxide-coated nickel-manganese precursor is (1.00˜1.05):1.
13. The preparation method according to claim 10 , wherein the second calcining process further comprises: decreasing the temperature of the second calcining reaction to the room temperature, to obtain a second calcined product; and performing ultracentrifugal grinding and sieving on the product of the second calcining process, wherein a sieving aperture of the sieving process is 300-400 meshes, to obtain the lithium nickel manganese oxide composite material in the form of a single crystal.
14. A lithium nickel manganese oxide composite material, wherein the lithium nickel manganese oxide composite material is prepared by the preparation method according to claim 1 .
15. The lithium nickel manganese oxide composite material according to claim 14 , wherein in the lithium nickel manganese oxide composite material, a coating amount of the nano-oxide is 0.1-0.3%.
16. A lithium ion battery, comprising a positive electrode material, wherein the positive electrode material comprises the lithium nickel manganese oxide composite material according to claim 14 .
17. The lithium nickel manganese oxide composite material according to claim 14 , wherein before performing the first calcining process, the preparation method further comprises:
performing a first mixing step on the nano-oxide and the nickel-manganese precursor, to obtain a first mixture;
wherein the first mixing step process is mixed for 10-20 min at a rotation speed of 2000-3000 rpm.
18. The lithium nickel manganese oxide composite material according to claim 17 , wherein the nano-oxide is a mixture of zirconium oxide and aluminum oxide, a weight ratio of the zirconium oxide, the aluminum oxide and the nickel-manganese precursor is (0.001-0.003):(0.001-0.003):1.
19. The preparation method according to claim 1 , wherein a particle size of the nano-oxide is 300-700 nm.
20. The preparation method according to claim 1 , the preparation method further comprises: sieving a product of the first calcining process, to obtain the oxide-coated nickel-manganese precursor, and a sieving aperture of the sieving process is 300-400 meshes.