Rechargeable lithium battery
A rechargeable lithium battery including: a negative electrode having a composite negative active material of a metal and a carbonaceous material; a positive electrode having a mixed positive active material of about 90 to 99 wt % of a first positive active material selected from cobalt, manganese, phosphate acid-based, or combinations thereof and about 1 to about 10 wt % of a nickel-based second positive active material; and a non-aqueous electrolyte.
1. A rechargeable lithium battery comprising:
a negative electrode comprising a composite negative active material of a metal or a semi-metal and a carbonaceous material;
a positive electrode comprising a mixed positive active material of about 90 to about 99 wt % of a first positive active material selected from the group consisting of cobalt, manganese, phosphate-based materials, or combinations thereof, and about 1 to about 10 wt % of a nickel-based second positive active material; and a non-aqueous electrolyte;
wherein the metal or the semi-metal is one metal, semi-metal or alloy selected from the group consisting of Si, an Si-T alloy, where T is an element selected from an alkali metal, an alkaline-earth metal, a group 13 element, a group 14 element, a transition element, a rare earth element, or combinations thereof, and is not Si, Sn, a Sn—Z alloy, where Z is an element selected from an alkali metal, an alkaline-earth metal, a group 13 element, a group 14 element, a transition element, a rare earth element, or combinations thereof and is not Sn, and combination thereof; and wherein the second positive active material is a compound represented by the following Formulae 10 or 11:
Li g Ni h L 1-j O e Formula 10
wherein 0.8≦g≦2, 0≦h≦1, e is from 1 to 2, 0≦j≦1, 0≦h+j≦1, and
L is selected from Al, Mn, Mg, Zr, La, or combinations thereof,
LixNiyCo z L′1 -y-z O q Formula 11
wherein, 0.65≦x≦1, 0≦y≦1, 0≦z≦1, 0≦y+z≦1, q ranges from 1.8 to 2, 0≦y+z≦1,
and L′ is selected from Al, Mn, Mg, Zr, La, or combinations thereof.
2. The rechargeable lithium battery of claim 1 , wherein the mixed positive active material comprises 3 to 5 wt % of the second positive active material and 97 to 95 wt % of the first positive active material.
3. The rechargeable lithium battery of claim 1 , wherein the first positive active material is at least one compound selected from the group represented by the following Formulae 1 to 9:
Li -a A 1-b X b D 2 (0.90 ≦a≦ 1.8,0 ≦b< 0.5) Formula 1
Li a E 1-b X b O 2 - c D c (0.90 ≦a≦ 1.8,0 ≦b< 0.5,0 ≦c≦ 0.05) Formula 2
LiE 2-b X b O 4-c D c (0 ≦b<< 0.5,0 ≦c≦ 0.05) Formula 3
Li a CoG b O 2 (0.90 ≦a≦ 1.8,0.001≦b≦0.1) Formula 4
Li a MnG b O 2 (0.90 ≦a≦ 1.8,0.001 ≦b≦ 0.1) Formula 5
Li a Mn 2 G b O 4 (0.90 ≦a≦ 1.8,0.001 ≦b≦ 0.1) Formula 6
Li (3-f) J 2 (PO 4 ) 3 (0 ≦f≦ 2) Formula 7
Li 3 Fe 2 (PO 4 ) 3 Formula 8
LiFePO 4 Formula 9
wherein A is selected from Co, Mn, or combinations thereof,
X is selected from Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or combinations thereof,
D is selected from O, F, S, P, or combinations thereof,
E is selected from Co, Mn, or combinations thereof,
G is selected from Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or combinations thereof, and
J is selected from V, Cr, Mn, Co, Ni, Cu or combinations thereof.
4. The rechargeable lithium battery of claim 1 , wherein the rechargeable lithium battery has an N/P ratio of about 1.03 to about 1.12, which is the ratio of negative electrode capacity to positive electrode capacity.
5. The rechargeable lithium battery of claim 1 , wherein the negative electrode has a potential of about 0.9V or less, which is measured by a measuring device of electrode potential in a 3-electrode system.
6. The rechargeable lithium battery of claim 1 , wherein the composite negative active material comprises:
a crystalline carbon core formed with pores;
an amorphous carbon shell formed on the crystalline carbon core;
metal nano-particles dispersed in the pores; and
amorphous carbon present in the pores.
7. The rechargeable lithium battery of claim 1 , wherein the elements T and Z are selected from the group consisting of Mg, Ca, Sr, Ba, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Re, Bh, Fe, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, In, Ti, Ge, P, As, Sb, Bi, S, Se, Te, or combinations thereof.
8. The rechargeable lithium battery of claim 6 , wherein the composite negative active material has a porosity of about 30 to about 50 volume %.
9. The rechargeable lithium battery of claim 6 , wherein:
the metal nano-particles have an average particle diameter of 600 nm or less, and
the concentration of the metal nano-particles is about 5 wt % or more.
10. The rechargeable lithium battery of claim 9 , wherein the average particle size of the metal nano-particles is 100 nm to 500 nm.
11. The rechargeable lithium battery of claim 9 , wherein the concentration of the metal nano-particles is 5 to 30 wt %.
12. The rechargeable lithium battery of claim 6 , wherein the composite negative active material has a particle size of about 5 to about 40 μm.