Positive active materials for rechargeable lithium battery, positive electrode including same and rechargeable lithium battery
A positive active material includes a compound represented by Chemical Formula 1, and the positive electrode including a positive active material and a rechargeable lithium battery including the same are provided. Li (1.33−0.67x−z) Mn (0.67−0.33x−0.5y) Ni (x−0.5y+z) M (y) O 2 [Chemical Formula 1] Definitions of Chemical Formula 1 are the same as in the detailed description.
1. A positive active material comprising a compound represented by Chemical Formula 1:
Li (1.33−0.67x−z) Mn (0.67−0.33x−0.5y) Ni (x−0.5y+z) M (y) O 2 [Chemical Formula 1]
wherein the M is Co, Cr, or a combination thereof, and
wherein the Li (1.33−0.67x−z) Mn (0.67−0.33x−0.5y) Ni (x−0.5y+z) M (y) O 2 comprises, on the basis of a total relative atomic amount of oxygen (O) being 2 and a total relative atomic amount of a combination of the Li, Mn, Ni and M being 2 in the Chemical Formula 1:
the M at an amount represented by the (y), wherein the y has a value greater than 0 and less than 0.13,
the Mn at an amount represented by the (0.67−0.33x−0.5y), wherein the x and y have values such that the amount of Mn is greater than 0.5 and less than 0.6,
the Li at an amount represented by the (1.33−0.67x−z), wherein the x and z have values such that the amount of Li is greater than 1 and less than 1.2, and
the Ni at an amount represented by the (x−0.5y+z), wherein the x, y and z have values such that the amount of Ni is greater than 0.2 and less than 0.5.
2. The positive active material of claim 1 , wherein the Mn comprises Mn having an oxidation number of +3 and Mn having an oxidation number of +4.
3. The positive active material of claim 2 , wherein a content (k, wt %) of the Mn having an oxidation number of +3 based on the total amount of the Mn is represented by Equation 1:
k= 100 z /(0.67−0.33 x− 0.5 y ). [Equation 1]
4. The positive active material of claim 2 , wherein the content of the Mn having an oxidation number of +3 is greater than about 0 wt % and less than about 37 wt %.
5. The positive active material of claim 2 , wherein the content of the Mn having an oxidation number of +3 is greater than about 5 wt % and less than about 10 wt %.
6. The positive active material of claim 1 , wherein in Chemical Formula 1, M is Co.
7. The positive active material of claim 1 , wherein in Chemical Formula 1, 1<1.33−0.67x−z<1.15, 0.5<0.67−0.33x−0.5y<0.6, 0.24<x−0.5y+z<0.4, and 0<y<0.13.
8. The positive active material of claim 1 , wherein in Chemical Formula 1, 0.06<y<0.09.
9. The positive active material of claim 8 , wherein in Chemical Formula 1, 0.52<0.67−0.33x−0.5y<0.56.
10. A positive electrode including a positive active material comprising a compound represented by Chemical Formula 1:
Li (1.33−0.67x−z) Mn (0.67−0.33x−0.5y) Ni (x−0.5y+z) M (y) O 2 [Chemical Formula 1]
wherein,
M is Co, Cr, or a combination thereof,
1<1.33−0.67x−z<1.2, 0.5<0.67−0.33x−0.5y<0.6, 0.2<x−0.5y+z<0.5, and 0<y<0.13.
11. A rechargeable lithium battery comprising
a positive electrode comprising:
a compound represented by Chemical Formula 1:
Li (1.33−0.67x−z) Mn (0.67−0.33x−0.5y) Ni (x−0.5y+z) M (y) O 2 [Chemical Formula 1]
wherein M is Co, Cr, or a combination thereof, and
wherein the Li (1.33−0.67x−z) Mn (0.67−0.33x−0.5y) Ni (x−0.5y+z) M (y) O 2 comprises, on the basis of a total relative atomic amount of oxygen (O) being 2 and a total relative atomic amount of a combination of the Li, Mn, Ni and M being 2 in the Chemical Formula 1:
the M at an amount represented by the (y), wherein the y has a value greater than 0 and less than 0.13,
Mn at an amount represented by the (0.67−0.33x−0.5y), wherein the x and y have values such that the amount of Mn is greater than 0.5 and less than 0.6,
Li at an amount represented by the (1.33−0.67x−z), wherein the x and z have values such that the amount of Li is greater than 1 and less than 1.2, and
Ni at an amount represented by the (x−0.5y+z), wherein the x, y and z have values such that the amount of Ni is greater than 0.2 and less than 0.5;
a negative electrode including a negative active material, and
an electrolyte.
12. The rechargeable lithium battery of claim 11 , wherein the Mn comprises Mn having an oxidation number of +3 and Mn having an oxidation number of +4.
13. The rechargeable lithium battery of claim 11 , wherein a content (k, wt %) of the Mn having an oxidation number of +3 based on the total amount of the Mn is represented by Equation 1:
k= 100 z /(0.67−0.33 x− 0.5 y ) [Equation 1].
14. The rechargeable lithium battery of claim 13 , wherein the content of the Mn having an oxidation number of +3 is greater than about 0 wt % and less than about 37 wt %.
15. The rechargeable lithium battery of claim 13 , wherein the content of the Mn having an oxidation number of +3 is greater than about 5 wt % and less than about 10 wt %.
16. The rechargeable lithium battery of claim 11 , wherein in Chemical Formula 1, M is Co.
17. The rechargeable lithium battery of claim 11 , wherein in Chemical Formula 1, 1<1.33−0.67x−z<1.15, 0.5<0.67−0.33x−0.5y<0.6, 0.24<x−0.5y+z<0.4, and 0<y<0.13.
18. The rechargeable lithium battery of claim 11 , wherein in Chemical Formula 1, 0.06<y<0.09.
19. The rechargeable lithium battery of claim 11 , wherein in Chemical Formula 1, 0.52<0.67−0.33x−0.5y<0.56.