Positive active material for rechargeable lithium battery, preparing method thereof and rechargeable lithium battery comprising positive electrode including positive active material
A positive active material for a rechargeable lithium battery includes a first positive active material including a secondary particle including at least two agglomerated primary particles, where at least one part of the primary particles has a radial arrangement structure, as well as a second positive active material having a monolith structure. The first and second positive active materials may both include nickel-based positive active materials. A method of preparing the positive active material, and a rechargeable lithium battery including a positive electrode including the positive active material are also provided.
1. A positive active material for a rechargeable lithium battery, comprising:
a first positive active material comprising a secondary particle comprising at least two agglomerated primary particles, at least one part of the primary particles having a radial arrangement structure; and
a second positive active material having a monolith structure,
wherein both of the first positive active material and the second positive active material comprise a nickel-based positive active material.
2. The positive active material of claim 1 , wherein the second positive active material is included in an amount of about 10 wt % to about 50 wt % based on a total weight of the positive active material.
3. The positive active material of claim 1 , wherein:
the secondary particle comprises a radial arrangement structure, or
the secondary particle comprises an internal part comprising an irregular porous structure and an external part comprising a radial arrangement structure.
4. The positive active material of claim 1 , wherein the primary particles have a plate shape, and
a long-axis of at least one part of the primary particles is arranged in a radial direction.
5. The positive active material of claim 1 , wherein an average length of the primary particles is about 0.01 μm to about 5 μm.
6. The positive active material of claim 1 , wherein an average particle diameter of the second positive active material is about 0.05 μm to about 10 μm.
7. The positive active material of claim 1 , wherein a residual lithium concentration in the positive active material is less than or equal to about 1200 ppm.
8. The positive active material of claim 1 , wherein the first positive active material is represented by Chemical Formula 1:
Li a (Ni 1-x-y-z Co x Mn y M z )O 2 , Chemical Formula 1
wherein, in Chemical Formula 1, M is an element selected from boron (B), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zirconium (Zr), and aluminum (Al),
0.95≤a≤1.3, x≤(1-x-y-z), y≤(1-x-y-z), 0<x<1, 0≤y<1, and 0≤z<1.
9. The positive active material of claim 1 , wherein the second positive active material is represented by Chemical Formula 1:
Li a (Ni 1-x-y-z Co x Mn y M z )O 2 Chemical Formula 1
wherein, in Chemical Formula 1, M is an element selected from boron (B), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zirconium (Zr), and aluminum (Al),
0.95≤a≤1.3, x≤(1-x-y-z), y≤(1-x-y-z), 0<x<1, 0≤y<1, and 0≤z<1.
10. A rechargeable lithium battery, comprising:
a positive electrode comprising the positive active material of claim 1 ;
a negative electrode; and
an electrolyte between the positive electrode and the negative electrode.
11. The rechargeable lithium battery of claim 10 , wherein the second positive active material is included in an amount of about 10 wt % to about 50 wt % based on a total weight of the positive active material.
12. The rechargeable lithium battery of claim 10 , wherein:
the secondary particle comprises a radial arrangement structure, or
the secondary particle comprises an internal part comprising an irregular porous structure and an external part comprising a radial arrangement structure.
13. The rechargeable lithium battery of claim 10 , wherein the primary particles have a plate shape, and
a long-axis of at least one part of the primary particles is arranged in a radial direction.
14. The rechargeable lithium battery of claim 10 , wherein a residual lithium concentration in the positive active material is less than or equal to about 1200 ppm.
15. The rechargeable lithium battery of claim 10 , wherein the first positive active material is represented by Chemical Formula 1:
Li a (Ni 1-x-y-z Co x Mn y M z )O 2 , Chemical Formula 1
wherein, in Chemical Formula 1, M is an element selected from boron (B), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zirconium (Zr), and aluminum (Al),
0.95≤a≤1.3, x≤(1-x-y-z), y≤(1-x-y-z), 0<x<1, 0≤y<1, and 0≤z<1.
16. The rechargeable lithium battery of claim 10 , wherein the second positive active material is represented by Chemical Formula 1:
Li a (Ni 1-x-y-z Co x Mn y M z )O 2 Chemical Formula 1
wherein, in Chemical Formula 1, M is an element selected from boron (B), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zirconium (Zr), and aluminum (Al),
0.95≤a≤1.3, x≤(1-x-y-z), y≤(1-x-y-z), 0<x<1, 0≤y<1, and 0≤z<1.