Positive electrode material formed by a lamellar-type oxide for a lithium battery
View Patent ↗A lamellar-type oxide, in particular used as active material of a positive electrode for a lithium battery and to a method for synthesizing such an oxide. The oxides are used as active materials for the positive electrode of a lithium battery. With such oxides, the specific capacity of a lithium battery is improved and stabilized on cycling.
1. A lamellar-type oxide of general formula xLi 2 MnO 3 .(1−x)LiM 1 a M 2 b M 3 c O 2 , with:
x is about 0.75,
M 1 is a chemical element selected from a first group consisting of Mn, Ni, Co, Fe, Ti, Cr, V and Cu,
M 3 is at least a chemical element selected from a second group consisting of Mg, Zn, Al, Na, Ca, Li, K, Sc, B, C, Si, P and S,
M 2 is a chemical element selected from the first group and the second group and it is different from M 1 and from M 3 , and
a+b+c=1, with a, b and c not zero.
2. The oxide according to claim 1 , wherein M 1 =Ni, M 2 =Mn, and M 3 =Mg.
3. The oxide according to claim 1 , wherein b=c.
4. The oxide according to claim 1 , wherein it is represented by the formula 0.75Li 2 MnO 3 .0.25LiNi 0.9 Mn 0.05 Mg 0.05 O 2 .
5. The oxide according to claim 1 , wherein it is represented by the formula 0.75Li 2 MnO 3 .0.25LiNi 0.6 Mn 0.2 Mg 0.2 O 2 .
6. A method for synthesizing a lamellar-type oxide of general formula xLi 2 MnO 3 .(1−x)LiM 1 a M 2 b M 3 c O 2 , with:
x is about 0.75,
M 1 is a chemical element selected from a first group consisting of Mn, Ni, Co, Fe, Ti, Cr, V and Cu,
M 3 is at least a chemical element selected from a second group consisting of Mg, Zn, Al, Na, Ca, Li, K, Sc, B, C, Si, P and S,
M 2 is a chemical element selected from the first group and the second group and it is different from M 1 and from M 3 , and
a+b+c=1, with a, b and c not zero
wherein the method comprises heat treatment of a powder obtained by mixing a precursor of general formula Mn x M l a(1-x) M 2 b(1-x) M 3 c(1-x) (OH) 2 with lithium hydroxide, followed by very rapid cooling of said powder,
wherein the heat treatment of the powder is achieved at a temperature greater than or equal to 800° C.
7. The method according to claim 6 , wherein after the very rapid cooling, the powder undergoes post-treatment in a slightly acid aqueous solution.
8. The method according to claim 6 , wherein the very rapid cooling is achieved by quenching.
9. The method according to claim 6 , wherein M 1 =Ni, M 2 =Mn, and M 3 =Mg.
10. The method according to claim 6 , wherein, wherein b=c.
11. The method according to claim 6 , wherein the precursor is represented by the general formula Mn 0.7625 Ni 0.225 Mg 0.0125 (OH) 2 .
12. The method according to claim 6 , wherein the precursor is represented by the general formula Mn 0.8 Ni 0.15 Mg 0.05 (OH) 2 .
13. A positive electrode comprising an active material wherein the active material consists of a lamellar-type oxide of general formula:
x Li 2 MnO 3 .(1− x )LiM 1 a M 2 b M 3 c O 2
with:
x is about 0.75,
M 1 is a chemical element selected from a first group consisting of Mn, Ni, Co, Fe, Ti, Cr, V and Cu,
M 3 is at least a chemical element selected from a second group consisting of Mg, Zn, Al, Na, Ca, Li, K, Sc, B, C, Si, P and S,
M 2 is a chemical element selected from the first group and the second group and it is different from M 1 and from M 3 ,
a+b+c=1, with a, b and c not zero.
14. The positive electrode according to claim 13 , wherein M 1 =Ni, M 2 =Mn, and M 3 =Mg.
15. The positive electrode according to claim 13 , wherein b=c.
16. The positive electrode according to claim 13 , wherein the lamellar-type oxide is represented by the formula 0.75Li 2 MnO 3 .0.25LiNi 0.9 Mn 0.05 Mg 0.05 O 2 .
17. The positive electrode according to claim 13 , wherein the lamellar-type oxide is represented by the formula 0.75Li 2 MnO 3 .0.25LiNi 0.6 Mn 0.2 Mg 0.2 O 2 .
18. A lithium battery including a positive electrode wherein the positive electrode comprises as active material a lamellar-type oxide of general formula
x Li 2 MnO 3 .(1− x )LiM 1 a M 2 b M 3 c O 2 , with:
x is about 0.75,
M 1 is a chemical element selected from a first group consisting of Mn, Ni, Co, Fe, Ti, Cr, V and Cu,
M 3 is at least a chemical element selected from a second group consisting of Mg, Zn, Al, Na, Ca, Li, K, Sc, B, C, Si, P and S,
M 2 is a chemical element selected from the first group and the second group and it is different from M 1 and from M 3 , and
a+b+c=1, with a, b and c not zero.
19. The lithium battery according to claim 18 , wherein M 1 =Ni, M 2 =Mn, and M 3 =Mg.
20. The lithium battery according to claim 18 , wherein b=c.
21. The lithium battery according to claim 18 , wherein the lamellar-type oxide is represented by the formula 0.75Li 2 MnO 3 .0.25LiNi 0.9 Mn 0.05 Mg 0.05 O 2 .
22. The lithium battery according to claim 18 , wherein the lamellar-type oxide is represented by the formula 0.75Li 2 MnO 3 .0.25LiNi 0.6 Mn 0.2 Mg 0.2 O 2 .