LITHIUM-NICKEL-MANGANESE-BASED COMPOSITE OXIDE MATERIAL, SECONDARY BATTERY, AND ELECTRIC APPARATUS

1 . A lithium-nickel-manganese-based composite oxide material, wherein a K value of the lithium-nickel-manganese-based composite oxide material ranges from 1 to 2, and the K value is calculated through the following formula:

K=D v 50/ d v 50

wherein d v 50 is a volume median crystallite diameter of crystal particles of the lithium-nickel-manganese-based composite oxide material; and D v 50 is a volume median particle diameter of the lithium-nickel-manganese-based composite oxide material.

2 . The lithium-nickel-manganese-based composite oxide material according to claim 1 , wherein the volume median crystallite diameter d v 50 of the crystal particles of the lithium-nickel-manganese-based composite oxide material ranges from 5 μm to 15 μm, or optionally, 5.5 μm to 11 μm.

3 . The lithium-nickel-manganese-based composite oxide material according to claim 1 , wherein the volume median particle diameter D v 50 of the lithium-nickel-manganese-based composite oxide material ranges from 9 μm to 20 μm, or optionally, 9 μm to 11 μm.

4 . The lithium-nickel-manganese-based composite oxide material according to claim 1 , wherein the lithium-nickel-manganese-based composite oxide material comprises lithium-nickel-manganese-based composite oxide with a space group P4 3 32 and lithium-nickel-manganese-based composite oxide with a space group Fd-3m; and a percentage of the lithium-nickel-manganese-based composite oxide with the space group P4 3 32 is greater than a percentage of the lithium-nickel-manganese-based composite oxide with the space group Fd-3m.

5 . The lithium-nickel-manganese-based composite oxide material according to claim 4 , wherein a percentage by weight of the lithium-nickel-manganese-based composite oxide with the space group P4 3 32 in the lithium-nickel-manganese-based composite oxide material is greater than 50%, or optionally, ranges from 80% to 91%.

6 . The lithium-nickel-manganese-based composite oxide material according to claim 1 , wherein the lithium-nickel-manganese-based composite oxide material comprises Mn 3+ , and a percentage of Mn 3+ in the lithium-nickel-manganese-based composite oxide material is less than or equal to 5.5 wt %, or optionally, ranges from 1.0 wt % to 2.2 wt %.

7 . The lithium-nickel-manganese-based composite oxide material according to claim 1 , wherein a specific surface area of the lithium-nickel-manganese-based composite oxide material is less than 1 m 2 /g, or optionally, ranges from 0.1 m 2 /g to 0.9 m 2 /g.

8 . The lithium-nickel-manganese-based composite oxide material according to claim 1 , wherein a tap density of the lithium-nickel-manganese-based composite oxide material is greater than or equal to 1.9 g/cm 3 , or optionally, ranges from 1.9 m 2 /g to 3.0 m 2 /g.

9 . The lithium-nickel-manganese-based composite oxide material according to claim 1 , wherein the lithium-nickel-manganese-based composite oxide material comprises lithium-nickel-manganese-based composite oxide particles whose surfaces are at least partially provided with a coating layer;

optionally, a material of the coating layer comprises at least one of aluminum oxide, titanium oxide, zirconium oxide, boron oxide, rare-earth oxide, lithium salt, phosphate, borate, and fluoride;

optionally, the coating layer comprises a lithium fast-ion conductor layer; and

optionally, the coating layer has a multi-layer structure, and the coating layer comprises the lithium fast-ion conductor layer on an inner side and an aluminum oxide layer on an outer side.

10 . The lithium-nickel-manganese-based composite oxide material according to claim 9 , having one or more of the following characteristics:

(1) the lithium fast-ion conductor is selected from oxide-based, phosphate-based, borate-based, sulfide-based, and LiPON-based inorganic materials with lithium ion conductivity;

(2) the lithium fast-ion conductor comprises one or more of the following elements: phosphorus, titanium, zirconium, boron, and lithium; and

(3) the lithium fast-ion conductor is selected from Li 2 BO 3 , Li 3 PO 4 , or a combination thereof.

11 . The lithium-nickel-manganese-based composite oxide material according to claim 1 , wherein a general formula of the lithium-nickel-manganese-based composite oxide material is Formula I:

Li a Ni 0.5-x Mn 1.5-y M x+y O 4-z X z   Formula I

wherein in Formula I, an element M is selected from Ti, Zr, W, Nb, Al, Mg, P, Mo, V, Cr, Zn, or a combination thereof;

in Formula I, an element X is selected from F, Cl, I, or a combination thereof;

in Formula I, 0.9≤a≤1.1, −0.2≤x≤0.2, −0.2≤y≤0.3, and 0≤z≤1;

optionally, the element M is selected from Mg, Ti, or a combination thereof; and

optionally, the element X is F.

12 . A method for preparing lithium-nickel-manganese-based material composite oxide, comprising:

providing a precursor composition, wherein the precursor comprises a lithium source, a nickel source, and a manganese source; and

sintering the precursor composition to obtain the lithium-nickel-manganese-based composite oxide material, wherein

a K value of a lithium-nickel-manganese-based composite oxide material ranges from 1 to 2, and the K value is calculated through the following formula:

K=D v 50/ d v 50

wherein d v 50 is a volume median crystallite diameter of crystal particles of the lithium-nickel-manganese-based composite oxide material; and

D v 50 is a volume median particle diameter of the lithium-nickel-manganese-based composite oxide material.

13 . The method according to claim 12 , wherein a general formula of the lithium-nickel-manganese-based composite oxide material is Formula I:

Li a Ni 0.5-x Mn 1.5-y M x+y O 4-z X z   Formula I

wherein in Formula I, an element M is selected from Ti, Zr, W, Nb, Al, Mg, P, Mo, V, Cr, Zn, or a combination thereof;

in Formula I, an element X is selected from F, Cl, I, or a combination thereof; and

in Formula I, 0.9≤a≤1.1, −0.2≤x≤0.2 (for example, 0≤x≤0.2), −0.2≤y≤0.3 (for example, 0≤y≤0.3), and 0≤z≤1.

14 . The method according to claim 12 , satisfying one or more of the following:

(i) a ratio of a volume median particle diameter of the nickel source to a volume median particle diameter of the lithium-nickel-manganese-based composite oxide material ranges from 0.4 to 1;

(ii) a ratio of a volume median particle diameter of the manganese source to a volume median particle diameter of the lithium-nickel-manganese-based composite oxide material ranges from 0.4 to 1; and

(iii) a volume median particle diameter of the lithium source ranges from 1 μm to 20 μm.

15 . The method according to claim 12 , wherein the sintering comprises a first heat treatment stage; and

a peak temperature at the first heat treatment stage ranges from 950° C. to 1200° C., and a holding time of the peak temperature at the first heat treatment stage ranges from 5 hours to 30 hours.

16 . The method according to claim 15 , wherein a heating rate to the peak temperature during the first heat treatment is less than or equal to 5° C./min, or optionally, ranges from 0.5° C./min to 3° C./min.

17 . The method according to claim 12 , wherein the sintering further comprises a second heat treatment stage after the first heat treatment stage; and

a peak temperature at the second heat treatment stage ranges from 550° C. to 680° C., and a time at the second heat treatment stage ranges from 5 hours to 50 hours.

18 . The method according to claim 12 , further comprising subjecting the precursor composition to ball milling before the sintering, wherein

optionally, a ball milling time is longer than 2 hours, for example, optionally, ranges from 2 hours to 6 hours.

19 . A secondary battery, comprising a positive electrode plate, wherein the positive electrode plate comprises a positive electrode active material, and the positive electrode active material comprises the lithium-nickel-manganese-based composite oxide material according to claim 1 .

20 . An electric apparatus, comprising the secondary battery according to claim 19 .