Positive electrode for rechargeable lithium battery, method of preparing the same, and rechargeable lithium battery including the same
A positive electrode for a rechargeable lithium battery includes a positive active material including small particle diameter monolith particles having a particle diameter of about 1 μm to about 8 μm and including a first nickel-based lithium metal oxide, and large particle diameter secondary particles having a particle diameter of about 10 μm to about 20 μm and including a second nickel-based lithium metal oxide. An X-ray diffraction peak intensity ratio (I(003)/I(104)) of the positive electrode is greater than or equal to about 3. A rechargeable lithium battery includes the positive electrode.
1. A positive electrode for a rechargeable lithium battery, the positive electrode comprising:
a positive active material, comprising
small particle diameter monolith particles having a particle diameter of about 1 μm to about 8 μm and comprising a first nickel-based lithium metal oxide, and
large particle diameter secondary particles having a particle diameter of about 10 μm to about 20 μm and comprising a second nickel-based lithium metal oxide,
wherein the large particle diameter secondary particles are a compound represented by Chemical Formula 1:
Li a Ni x Q 1 1-x O 2 , and Chemical Formula 1
wherein, in Chemical Formula 1,
0.9≤a≤1.05, 0.9≤x≤0.98, and Q 1 is at least one element selected from Co, Mn, Al, Cr, Fe, Ca, B, V, Mg, Nb, Rb, Mo, Ta, W, Cu, Zn, Ga, In, La, Ce, Pr, Sn, Zr, Te, Ru, Ti, Pb, and Hf,
wherein an X-ray diffraction peak intensity ratio (I(003)/I(104)) of the positive electrode is greater than or equal to about 3.
2. The positive electrode of claim 1 , wherein the small particle diameter monolith particles are a compound represented by Chemical Formula 2:
Li b Ni y Q 2 1-y O 2 , and Chemical Formula 2
wherein, in Chemical Formula 2,
0.9≤b≤1.05, 0.3≤y≤0.98, and Q 2 is at least one element selected from Co, Mn, Al, Cr, Fe, Ca, B, V, Mg, Nb, Rb, Mo, Ta, W, Cu, Zn, Ga, In, La, Ce, Pr, Sn, Zr, Te, Ru, Ti, Pb, and Hf.
3. The positive electrode of claim 1 , wherein a ratio of nickel ions occupying lithium sites in the positive active material is less than or equal to about 2.0 atom %.
4. The positive electrode of claim 3 , wherein the ratio of nickel ions occupying lithium sites in the positive active material is about 0.0001 atom % to about 0.3 atom %.
5. The positive electrode of claim 1 , wherein a content of residual lithium in the positive active material is less than or equal to about 0.1 wt %.
6. The positive electrode of claim 5 , a content of LiOH in the positive active material is in a range of about 0.01 wt % to about 0.06 wt %, and a content of Li 2 CO 3 in the positive active material is in a range of about 0.05 wt % to about 0.1 wt %.
7. A positive electrode for a rechargeable lithium battery, the positive electrode comprising:
a positive active material, comprising
small particle diameter monolith particles having a particle diameter of about 1 μm to about 8 μm and comprising a first nickel-based lithium metal oxide, and
large particle diameter secondary particles having a particle diameter of about 10 μm to about 20 μm and comprising a second nickel-based lithium metal oxide,
wherein the small particle diameter monolith particles comprise nickel and aluminum,
wherein an X-ray diffraction peak intensity ratio (I(003)/I(104)) of the positive electrode is greater than or equal to about 3.
8. The positive electrode of claim 7 , wherein the small particle diameter monolith particles comprise nickel, cobalt, and aluminum.
9. The positive electrode of claim 7 , wherein the small particle diameter monolith particles are a compound represented by Chemical Formula 2:
Li b Ni y Q 2 1-y O 2 , and Chemical Formula 2
wherein, in Chemical Formula 2,
0.9≤b≤1.05, 0.3≤y≤0.98, and Q 2 is Al and at least one element selected from Co, Mn, Cr, Fe, Ca, B, V, Mg, Nb, Rb, Mo, Ta, W, Cu, Zn, Ga, In, La, Ce, Pr, Sn, Zr, Te, Ru, Ti, Pb, and Hf.
10. The positive electrode of claim 9 , Q 2 comprises Al and Co.
11. The positive electrode of claim 7 , wherein the large particle diameter secondary particles are a compound represented by Chemical Formula 1:
Li a Ni x Q 1 1-x O 2 , and Chemical Formula 1
wherein, in Chemical Formula 1,
0.9≤a≤1.05, 0.9≤x≤0.98, and Q 1 is at least one element selected from Co, Mn, Al, Cr, Fe, Ca, B, V, Mg, Nb, Rb, Mo, Ta, W, Cu, Zn, Ga, In, La, Ce, Pr, Sn, Zr, Te, Ru, Ti, Pb, and Hf.
12. The positive electrode of claim 7 , wherein a ratio of nickel ions occupying lithium sites in the positive active material is less than or equal to about 2.0 atom %.
13. The positive electrode of claim 12 , wherein the ratio of nickel ions occupying lithium sites in the positive active material is about 0.0001 atom % to about 0.3 atom %.
14. The positive electrode of claim 7 , wherein a content of residual lithium in the positive active material is less than or equal to about 0.1 wt %.
15. The positive electrode of claim 14 , a content of LiOH in the positive active material is in a range of about 0.01 wt % to about 0.06 wt %, and a content of Li 2 CO 3 in the positive active material is in a range of about 0.05 wt % to about 0.1 wt %.
16. A positive electrode for a rechargeable lithium battery, the positive electrode comprising:
a positive active material, comprising
small particle diameter monolith particles having a particle diameter of about 1 μm to about 8 μm and comprising a first nickel-based lithium metal oxide, and
large particle diameter secondary particles having a particle diameter of about 10 μm to about 20 μm and comprising a second nickel-based lithium metal oxide,
wherein the large particle diameter secondary particles have a form in which two or more primary particles are aggregated, and the primary particles have a particle diameter of about 20 nm to about 500 nm,
wherein an X-ray diffraction peak intensity ratio (I(003)/I(104)) of the positive electrode is greater than or equal to about 3.
17. The positive electrode of claim 16 , wherein the large particle diameter secondary particles are a compound represented by Chemical Formula 1:
Li a Ni x Q 1 1-x O 2 , and Chemical Formula 1
wherein, in Chemical Formula 1,
0.9≤a≤1.05, 0.9≤x≤0.98, and Q 1 is at least one element selected from Co, Mn, Al, Cr, Fe, Ca, B, V, Mg, Nb, Rb, Mo, Ta, W, Cu, Zn, Ga, In, La, Ce, Pr, Sn, Zr, Te, Ru, Ti, Pb, and Hf.
18. The positive electrode of claim 16 , wherein the small particle diameter monolith particles are a compound represented by Chemical Formula 2:
Li b Ni y Q 2 1-y O 2 , and Chemical Formula 2
wherein, in Chemical Formula 2,
0.9≤ b≤1.05, 0.3≤ y≤0.98, and Q 2 is at least one element selected from Co, Mn, Al, Cr, Fe, Ca, B, V, Mg, Nb, Rb, Mo, Ta, W, Cu, Zn, Ga, In, La, Ce, Pr, Sn, Zr, Te, Ru, Ti, Pb, and Hf.
19. The positive electrode of claim 16 , wherein a ratio of nickel ions occupying lithium sites in the positive active material is less than or equal to about 2.0 atom %.
20. The positive electrode of claim 19 , wherein the ratio of nickel ions occupying lithium sites in the positive active material is about 0.0001 atom % to about 0.3 atom %.
21. The positive electrode of claim 16 , wherein a content of residual lithium in the positive active material is less than or equal to about 0.1 wt %.
22. The positive electrode of claim 21 , a content of LiOH in the positive active material is in a range of about 0.01 wt % to about 0.06 wt %, and a content of Li 2 CO 3 in the positive active material is in a range of about 0.05 wt % to about 0.1 wt %.