Ni based cathode material for rechargeable lithium-ion batteries
The invention provides a positive electrode material for lithium ion batteries, comprising a lithium transition metal-based oxide powder having a general formula Li 1+a ((Ni z (Ni 0.5 Mn 0.5 ) y Co x ) 1−k A k ) 1−a O 2 , wherein A is a dopant, with −0.025≤a≤0.025, 0.15≤x≤0.22, 0.42≤z≤0.52, 1.075<z/y<1.300, x+y+z=1 and k≤0.01. Different embodiments provide the following features: the lithium transition metal-based oxide powder has a carbon content ≤1000 ppm or even ≤400 ppm; the lithium transition metal-based oxide powder has a sulfur content between 0.05 and 1.0 wt %; a dopant A is Zr, and the powder further comprises up to 1 wt % of a coating comprising a boron compound and WO 3 .
1. A positive electrode material for lithium ion batteries, comprising a lithium transition metal-based oxide powder having a general formula Li 1+a ((Ni z (Ni 0.5 Mn 0.5 ) y Co x ) 1−k A k ) 1−a O 2, wherein A is a dopant, 0≤a≤0.05, 0.15≤x≤0.20, z≤0.45, 1.125<z/y<1.285, x+y+z=1 and k≤0.01, and wherein the positive electrode active material has a crystallite size 26.1 nm to less than 41.5 nm as determined by the Sherrer equation based on the peak of the (104) plane obtained from the X-ray diffraction pattern using a Cu Kα radiation source, and capacity fade rate of below 20 %/100 cycles as determined according to Testing Method 1.
2. The positive electrode material of claim 1 , wherein 0.15≤x<0.18.
3. The positive electrode material of claim 1 , wherein the powder further comprises up to 1 wt % of a coating comprising either one or more of Al 2 O 3 , WO 3 , LiA 1 O 2 , LiF, Li 3 PO 4 , Li 2 ZrO 3 , Li 2 WO 4 , MgO and Li 2 TiO 3 .
4. The positive electrode material of claim 1 , wherein the powder further comprises up to 1 wt % of a coating comprising a boron compound.
5. The positive electrode material of claim 4 , wherein the boron compound is either one or more of LiBO 2 , Li 2 B 4 O 7 , B 2 O 3 and Li 3 BO 3 .
6. The positive electrode material of claim 1 , wherein the dopant A is either one or more of Al, Ca, W, B, Si, Ti, Mg and Zr.
7. The positive electrode material of claim 1 , wherein a dopant A is Zr, and wherein the powder further comprises up to 1 wt % of a coating comprising a boron compound and WO 3 .
8. The positive electrode material of claim 1 , wherein 0≤a≤0.025.
9. The positive electrode material of claim 1 , wherein the lithium transition metal-based oxide powder has a carbon content ≤1000 ppm, wherein the carbon content in the positive electrode material is determined with an analysis of CO 2 and CO contents in a gas resulting from combustion of the positive electrode material.
10. The positive electrode material of claim 1 , wherein the lithium transition metal-based oxide powder has a sulfur content between 0.05 and 1.0 wt %.