Lithium ion battery and positive active material thereof
The present invention provides a positive electrode active material includes a first lithium transition metal oxide represented by formula Li a (Ni b Co c Mn d ) 1-e M e O 2 or Li a (Ni b Co c Al d ) 1-e M′ e O 2 , wherein 0.9<a<1.1, 0.6≤b<0.9, 0.1≤c<0.4, 0.05≤d<0.4, 0≤e≤0.1, b+c+d=1, M is at least one of Al, Mg, Ti, Zr, M′ is at least one of Mg, Ti, Zr, and a second lithium transition metal oxide represented by formula Li x Ni y Co z M″ s O 2 , wherein 0.9<x<1.1, 0.4≤y<0.6, 0.2≤z<0.5, 0.2≤s<0.5, y+z+s=1, M″ is at least one of Mn, Al, Mg, Ti, Zr, Fe, Cr, V, Ti, Cu, B, Ca, Zn, Nb, Mo, Sr, Sb, W, Bi. The positive electrode active material for a lithium ion battery of the present invention shows a high compacted density. The present invention also provides a lithium ion battery using the positive electrode active material of the present invention. The lithium ion battery has high gram capacity, high energy density, good storage performance, and good cycle stability.
1. A positive active material for a lithium ion battery, comprising:
a first lithium transition metal oxide represented by formula Li a (Ni b Co c Mn d ) 1-e M e O 2 or Li a (Ni b Co c Al d ) 1-e M′ e O 2 , wherein 0.9<a<1.1, 0.6≤b<0.9, 0.1≤c<0.4, 0.05≤d<0.4, 0≤e≤0.1, b+c+d=1, M is at least one of Al, Mg, Ti, Zr, M′ is at least one of Mg, Ti, Zr, and
a second lithium transition metal oxide represented by formula Li x Ni y Co z M″ s O 2 , wherein 0.9<x<1.1, 0.4≤y<0.6, 0.2≤z<0.5, 0.2≤s<0.5, y+z+s=1, M″ is at least one of Al, Mg, Ti, Zr, Fe, Cr, V, Cu, B, Ca, Zn, Nb, Mo, Sr, Sb, W, Bi, and wherein a weight ratio of the first lithium transition metal oxide to the second lithium transition metal oxide is 50:50 to 60:40.
2. The positive active material of claim 1 , wherein the first lithium transition metal oxide has a median particle size of 10 μm<D50≤20 μm, and the second lithium transition metal oxide has a median particle size of 6 μm<D50≤10 μm.
3. The positive active material of claim 1 , wherein a compacted density of the positive electrode active material is more than 3.4 g/cm 3 .
4. The positive active material of claim 1 , wherein in the second lithium transition metal oxide represented by formula Li x Ni y Co z M″ s O 2 , 0.9<x<1.1, 0.5≤y≤0.55, 0.2≤z<0.5, 0.2≤s<0.5, y+z+s=1, M″ is Al.
5. A lithium ion battery, comprising a positive electrode plate containing a positive active material, a negative electrode plate containing a negative active material, a separator interposed between the positive electrode plate and the negative electrode plate, and an electrolyte, wherein the positive active material is the positive active material of any one of claim 1 .
6. The lithium ion battery of claim 5 , wherein the electrolyte comprises a lithium salt, and the lithium salt is selected from at least one of LiN(C p F 2p+1 SO 2 )(C q F 2q+1 SO 2 ), LiPF 6 , LiBF 4 , LiBOB, LiAsF 6 , LiCF 3 SO 3 , LiClO 4 , wherein p, q is a natural number.
7. The lithium ion battery of claim 5 , wherein the negative active material is selected from at least one of soft carbon, hard carbon, artificial graphite, natural graphite, silicon, silicon oxide compound, silicon carbon composite, lithium titanate, and a metal that can form an alloy with lithium.