Method for preparing a positive active material for a lithium secondary battery
First Claim
1. A method for preparing a positive active material for a secondary lithium battery, comprising the steps of:
- 1) synthesizing a first intermediate product of a core represented by formula LixMyN1-yO2-α
Aβ
, wherein the first intermediate product is a compound containing an element represented by M or is a compound containing elements represented by M and N;
2) adding phosphorous (P) containing source into the first intermediate product of step
1) and sintering a mixture of the phosphorous (P) containing source and the first intermediate product at 200˜
1200°
C., and obtaining a second intermediate product coated with a coating layer which does not contain lithium;
3) adding degradable lithium salt into the second intermediate product of step
2) and sintering a mixture of the second intermediate product coated with the coating layer which does not contain lithium and the degradable lithium salt at 400˜
1200°
C., and obtaining a positive active material including a core and a coating layer coating the core;
wherein the core of the positive active material is a lithium transition metal oxide represented by formula LixMyN1-yO2-α
Aβ
, the coating layer is a lithium transition metal phosphate represented by formula LiaMbN′
1-bPO4-λ
Bζ
in situ formed on a surface of the core, and the element represented by M is at least one of Ni, Co and Mn;
the element represented by N and N′
each is at least one of Na, K, Rb, Cs, Be, Mg, Ca, Sr, Ba, Ra, Al, Ga, In, Ge, Sn, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu;
element represented by A and B each is at least one of N, F, P, S, Cl, Se; and
0.9≤
x≤
1.2, 0.6≤
y≤
1.0, 0.9≤
a≤
1.1, 0.6≤
b≤
1.0, 0≤
α
≤
0.2, 0≤
β
≤
0.4, 0≤
λ
≤
0.5, 0≤
ζ
≤
0.5.
1 Assignment
0 Petitions
Accused Products
Abstract
The present invention provides a method for preparing a positive active material for a secondary lithium battery. The method includes the steps of: synthesizing an intermediate product of a core represented by formula LixMyN1-yO2-αAβ; adding P source into the intermediate product to obtain a phosphate which does not contain lithium; and adding lithium source into the mixture of the phosphate and LixMyN1-yO2-αAβ and sintering to obtain the positive active material for secondary lithium battery. The method for preparing a positive active material for a secondary lithium battery of the present invention has the following advantages: 1) the P source can be dispersed on the surface of the core more uniformly; 2) the coating layer can be bonded to the core more tightly; and 3) the positive active material has higher rate discharge performance.
3 Citations
11 Claims
-
1. A method for preparing a positive active material for a secondary lithium battery, comprising the steps of:
-
1) synthesizing a first intermediate product of a core represented by formula LixMyN1-yO2-α
Aβ
, wherein the first intermediate product is a compound containing an element represented by M or is a compound containing elements represented by M and N;2) adding phosphorous (P) containing source into the first intermediate product of step
1) and sintering a mixture of the phosphorous (P) containing source and the first intermediate product at 200˜
1200°
C., and obtaining a second intermediate product coated with a coating layer which does not contain lithium;3) adding degradable lithium salt into the second intermediate product of step
2) and sintering a mixture of the second intermediate product coated with the coating layer which does not contain lithium and the degradable lithium salt at 400˜
1200°
C., and obtaining a positive active material including a core and a coating layer coating the core;wherein the core of the positive active material is a lithium transition metal oxide represented by formula LixMyN1-yO2-α
Aβ
, the coating layer is a lithium transition metal phosphate represented by formula LiaMbN′
1-bPO4-λ
Bζ
in situ formed on a surface of the core, and the element represented by M is at least one of Ni, Co and Mn;
the element represented by N and N′
each is at least one of Na, K, Rb, Cs, Be, Mg, Ca, Sr, Ba, Ra, Al, Ga, In, Ge, Sn, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu;
element represented by A and B each is at least one of N, F, P, S, Cl, Se; and
0.9≤
x≤
1.2, 0.6≤
y≤
1.0, 0.9≤
a≤
1.1, 0.6≤
b≤
1.0, 0≤
α
≤
0.2, 0≤
β
≤
0.4, 0≤
λ
≤
0.5, 0≤
ζ
≤
0.5. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
Specification