High-compacted-density positive electrode material and electrochemical energy storage apparatus
This application relates to the field of battery technologies, and in particular, to a high-compacted-density positive electrode material and an electrochemical energy storage apparatus. The positive electrode material includes a lithium-nickel transition metal oxide A and a lithium-nickel transition metal oxide B. The lithium-nickel transition metal oxide A is secondary particles, whose chemical formula is shown in formula I: Li a1 (Ni b1 Co c1 Mn d1 ) x1 M 1-x1 O 2-e1 X e1 . The lithium-nickel transition metal oxide B is a monocrystalline structure or a monocrystalline-like structure, whose chemical formula is shown in formula II: Li a2 (Ni b2 Co c2 Mn d2 ) x2 M′ 1-x2 O 2-e2 X′ e2 (II). The positive electrode material of this application includes the large-particle lithium-nickel transition metal oxide A and the small-particle lithium-nickel transition metal oxide B to improve an energy density of the battery. A degree of crystallinity and particle size distribution of the mixed positive electrode material can improve a compacted density of the high-nickel active material, and ensure lower gassing and good cycle performance.
1. A positive electrode material, wherein the positive electrode material includes a lithium-nickel transition metal oxide A and a lithium-nickel transition metal oxide B, the lithium-nickel transition metal oxide A is secondary particles, and a chemical formula of the lithium-nickel transition metal oxide A is shown in Formula I:
Li a1 (Ni b1 Co c1 Mn d1 ) x1 M 1-x1 O 2-e1 X e1 (I)
in Formula I, 0.95≤a1≤1.05, 0.7≤b1≤0.98, 0.01≤c1≤0.15, 0.01≤d1≤0.3, 0.95≤x1≤1, and 0≤e1≤0.1, wherein M is selected from any one or a combination of Al, Ti, Zr, Nb, Sr, Sc, Sb, Y, Ba, B, C, Co, and Mn, and X is selected from F and/or Cl;
the lithium-nickel transition metal oxide B is monocrystalline or monocrystalline-like particles, and a chemical formula of the lithium-nickel transition metal oxide B is shown in Formula II:
Li a2 (Ni b2 Co c2 Mn d2 ) x2 M′ 1-x2 O 2-e2 X′ e2 (II)
In Formula II, 0.95≤a2≤1.05, 0.7≤b2≤0.98, 0.01≤c2≤0.15, 0.01≤d2≤0.3, 0.95≤x2≤1, and 0≤e2≤0.1, where M′ is selected from any one or a combination of Al, Ti, Zr, Nb, Sr, Sc, Sb, Y, Ba, B, C, Co, and Mn, and X′ is selected from F and/or Cl; and
a crystal size D 104 of the positive electrode material and a particle size distribution change rate ΔPSD of the positive electrode material satisfy:
50 nm≤ D 104 ×ΔPSD≤450 nm, wherein
ΔPSD is a particle size distribution change rate calculated according to the formula ΔPSD=(D v 90−D v 10)/D v 50 based on a measured particle size of volume particle distribution of the positive electrode material, and D 104 is a crystal size obtained by fitting a peak value of a 104 crystal plane through XRD ray diffraction testing on the positive electrode material.
2. The positive electrode material according to claim 1 , wherein the positive electrode material satisfies: 80 nm≤D 104 ×ΔPSD≤250 nm.
3. The positive electrode material according to claim 1 , wherein ΔPSD is within a range of 1.2 to 3.1.
4. The positive electrode material according to claim 1 , wherein ΔPSD is within a range of 1.5 to 2.2.
5. The positive electrode material according to claim 1 , wherein the lithium-nickel transition metal oxide A has a single-particle pressure-resistant strength of ≥100 MPa, and the lithium-nickel transition metal oxide B has a single-particle pressure-resistant strength of ≥50 MPa.
6. The positive electrode material according to claim 1 , wherein the lithium-nickel transition metal oxide A has D v 50 of 8 μm to 15 μm, D v 10 of 3 μm to 8 μm, and D v 90 of 15 μm to 25 μm.
7. The positive electrode material according to claim 1 , wherein the lithium-nickel transition metal oxide A comprises secondary particles composed of primary particles, and the primary particles have a particle size of 30 nm to 800 nm.
8. The positive electrode material according to claim 1 , wherein the lithium-nickel transition metal oxide A comprises secondary particles composed of primary particles, and the primary particles have a particle size of 200 nm to 500 nm.
9. The positive electrode material according to claim 1 , wherein the lithium-nickel transition metal oxide B has D v 50 of 1 μm to 7 μm, D v 10 of 1 μm to 3 μm, and D v 90 of 5 μm to 10 μm.
10. The positive electrode material according to claim 1 , wherein the lithium-nickel transition metal oxide B has D v 50 of 3 μm to 5 μm, D v 10 of 1 μm to 3 μm, and D v 90 of 5 μm to 10 μm.
11. The positive electrode material according to claim 1 , wherein a mass ratio of the lithium-nickel transition metal oxide A to the lithium-nickel transition metal oxide B is 10:1 to 1:1.
12. The positive electrode material according to claim 1 , wherein a mass ratio of the lithium-nickel transition metal oxide A to the lithium-nickel transition metal oxide B is 4:1 to 2:1.
13. The positive electrode material according to claim 1 , wherein a specific surface area of the positive electrode material is 0.5 m 2 /g to 1.5 m 2 /g.
14. The positive electrode material according to claim 1 , wherein a specific surface area of the positive electrode material is 0.6 m 2 /g to 1.0 m 2 /g.
15. The positive electrode material according to claim 1 , wherein the positive electrode material has a compacted density of 3.3 g/cm 3 to 3.7 g/cm 3 .
16. The positive electrode material according to claim 1 , wherein the lithium-nickel transition metal oxide A and/or the lithium-nickel transition metal oxide B are surface-modified, the surface modification method comprising one or a combination of doping the particle surface, oxide coating the particle surface, and carbon coating the particle surface, wherein doping and coating elements are selected from one or a combination of Mg, Al, Ti, Co, Fe, Cd, Zr, Mo, Zn, B, P, Cu, V, and Ag.
17. An electrochemical energy storage apparatus, comprising the positive electrode material according to claim 1 .