Process of making cathode material containing Ni-based lithium transition metal oxide
View Patent ↗The present invention provides for a process of making a Ni-based lithium transition metal oxide cathode active materials used in lithium ion secondary batteries. The cathode active materials are substantially free of Li 2 CO 3 impurity and soluble bases.
1. A process for making a lithium transition metal oxide comprising:
(a) combining solid Li 2 CO 3 and a solid mixed transition metal precursor to form a mixture;
(b) performing a solid state reaction of the mixture in air; and
(c) forming the lithium transition metal oxide, the lithium transition metal oxide having a composition of the general formula
Li x ((Ni 1-a-b (Ni 1/2 Mn 1/2 ) a Co b ) 1-k A k ) 2-x O 2 ,
wherein 0.65≦a+b≦0.85, 0.1≦b≦0.4,
A is a dopant,
0≦k<0.05, and
0.95≦x≦1.05,
wherein the lithium transition metal oxide is substantially free of soluble bases such that less than about 20 ml of 0.1M HCl is necessary to titrate 200 ml of a solution containing substantially all of the soluble bases present in 10 q of said lithium transition metal oxide to a pH less than 5, said solution being prepared by repeated soaking and decanting of said lithium transition metal oxide.
2. The process of claim 1 , wherein the step of performing the solid state reaction in air comprises cooking at a temperature of between 700° C. and 950° C. under air circulation and sintering at a temperature of between 850° C. and 1020° C.
3. The process of claim 1 , wherein the solid mixed transition metal precursor is mixed hydroxide, mixed carbonate or mixed oxides.
4. The process of claim 3 , wherein the mixed hydroxide has the general formula MOOH, wherein M is Ni, Mn and Co.
5. The process of claim 4 , wherein the mixed hydroxide is prepared by an ammonia-free process.
6. The process of claim 1 , wherein less than about 10 ml of 0.1M HCl is necessary to titrate 200 ml of a solution containing substantially all of the soluble bases present in 10 g of the lithium transition metal oxide to a pH less than 5.
7. A process for large scale production of a lithium transition metal oxide comprising:
(a) combining solid Li 2 CO 3 and a solid mixed transition metal precursor to form a mixture;
(b) performing a solid state reaction of the mixture in air; and
(c) forming at least about 5 kg of the lithium transition metal oxide, the lithium transition metal oxide having the composition of the general formula
Li x ((Ni 1-a-b *Ni 1/2 Mn 1/2 ) a Co b ) 1-k A k ) 2-x O 2 ,
wherein 0.65≦a+b≦0.85, 0.1≦b≦0.4,
A is a dopant,
0≦k<0.05, and
0.95≦x≦1.05,
wherein the lithium transition metal oxide is substantially free of soluble bases such that less than about 20 ml of 0.1M HCl is necessary to titrate 200 ml of a solution containing substantially all of the soluble bases present in 10 q of said lithium transition metal oxide to a pH less than 5, said solution being prepared by repeated soaking and decanting of said lithium transition metal oxide.
8. The process of claim 7 , wherein the step of performing the solid state reaction in air comprises cooking at a temperature of between 700° C. and 950° C. under air circulation and sintering at a temperature of between 850° C. and 1020° C.
9. The process of claim 7 , wherein said solid mixed transition metal precursor is mixed hydroxide, mixed carbonate or mixed oxides.
10. The process of claim 7 , wherein the mixed hydroxide has the general formula MOOH, wherein M is Ni, Mn and Co.