Positive electrode materials combining high safety and high power in a Li rechargeable battery
The invention relates to a Li a Ni x Co y Mn y′ M′ z O 2 composite oxide for use as a cathode material in a rechargeable battery, with a non-homogenous Ni/M′ ratio in the particles, allowing excellent power and safety properties when used as positive electrode material in Li battery. More particularly, in the formula 0.9<a<1.1, 0.3≦x≦0.9, 0<y≦0.4, 0<y′≦0.4, 0<z≦0.35, e<0.02, 0≦f≦0.05 and 0.9<(x+y+y′+z+f)<1.1; M′ consists of either one or more elements from the group Al, Mg, Ti, Cr, V, Fe, Mn and Ga; N consists of either one or more elements from the group F, Cl, S, Zr, Ba, Y, Ca, B, Sn, Sb, Na and Zn. The powder has a particle size distribution defining a D10, D50 and D90; and the x and z parameters varying with the particles size of the powder, and is characterized in that either one or both of: x 1− x 2≧0.005 and z 2− z 1≧0.005; x1 and z1 being the parameters corresponding to particles having a particle size D90; and x2 and z2 being the parameters corresponding to particles having a particle size D10.
1. A lithium metal oxide powder for use as a cathode material in a rechargeable battery, having a general formula Li a Ni x Co y Mn y′ M′ z O 2±e A f , wherein
0.9<a<1.1, 0.3≦x≦0.9, 0≦y≦0.4, 0≦y′≦0.4, 0<z≦0.35, e<0.02, 0≦f≦0.05 and 0.9<(x+y+y′+z+f)<1.1;
wherein M′ comprises one or more elements selected from the group consisting of Al, Mg, Ti, Cr, V, Fe and Ga; A comprises one or more elements selected from the group consisting of F, C, Cl, S, Zr, Ba, Y, Ca, B, Sn, Sb, Na and Zn; and the powder has a particle size distribution defining a D10 and a D90; wherein either:
x1 −x 2≧0.005; or
z 2 −z 1≧0.005; or
both x1−x2≧0.005 and z2−z1≧0.005;
x1 and z1 being molar contents of Ni and M′, respectively, of particles having a particle size D90; and x2 and z2 being molar contents of Ni and M′, respectively, of particles having a particle size D10, and
wherein the molar contents of Co and Mn are not correlated to particle size.
2. The oxide powder of claim 1 , wherein both x1−x2≧0.020 and z2−z1≧0.020.
3. The oxide powder of claim 1 , wherein the Ni content of the powder increases with increasing particle size, and the M′ content of the powder decreases with increasing particle size.
4. The oxide powder of claim 1 , wherein A comprises S and C, with f≦0.02, and M′ comprises Al.
5. The oxide powder of claim 1 , wherein A comprises C, with f≦0.01, and M′ comprises Al.
6. A process for the manufacture of the powder of claim 1 , comprising:
providing an M-precursor powder, wherein M=Ni x Co y Mn y′ M′ z A f , having a particle size distribution defining a D10 and a D90; wherein either x1−x2≧0.005; or z2−z1≧0.005; or both x1−x2≧0.005 and z2−z1≧0.005; x1 and z1 being the values of x and z of particles having a particle size D90; and x2 and z2 being the values of x and z of particles having a particle size D10,
mixing the M-precursor powder with a lithium precursor, and
heating the mixture at a temperature of at least 800° C.
7. The process of claim 6 , wherein the lithium precursor is lithium carbonate.
8. The process of claim 6 , wherein providing an M-precursor powder comprises:
providing at least two M-precursor powders having a different particle size distribution, wherein the at least two M-precursor powders have different D10 and D90 values, and wherein an M-precursor powder having a lower D10 and D90 value has either one or both of a lower Ni content and a higher M′ content than an M-precursor powder having a higher D10 and D90 value; and
mixing the at least two M-precursor powders.
9. The process of claim 8 , wherein the at least two M-precursor powders are mixed with a lithium precursor, before heating the mixture at a temperature of at least 800° C.
10. The process of claim 8 , wherein the M-precursor powders comprise hydroxide or oxyhydroxide compositions obtained by precipitating metal sulphates, nitrates, chlorides or carbonates in the presence of an alkali hydroxide and a chelating agent.
11. The process of claim 10 , wherein the chelating agent is ammonia.
12. The process of claim 8 , wherein for the at least two M-precursor powders, both the Ni content of the powder having a lower D10 and D90 value is lower than the Ni content of the powder having a higher D10 and D90 value, and the M′ content of the powder having a lower D10 and D90 value is higher than the M′ content of the powder having a higher D10 and D90 value.
13. The process of claim 8 , wherein the difference between the Co content of the M-precursor powder having a lower D10 and D90 value, and the Co content of the M-precursor powder having a higher D10 and D90 value, is less than each one of the differences between the Ni and M′ contents of the M-precursor powders; and the difference between the Mn content of the M-precursor powder having a lower D10 and D90 value, and the Mn content of the M-precursor powder having a higher D10 and D90 value, is less than the difference between each one of the Ni and M′ contents of the M-precursor powders.
14. The powder of claim 2 , wherein both x1−x2≧0.030 and z2−z1≧0.030.