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 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, wherein the air supplied is at least 2 m 3 for 10 hour per 1 of the lithium transition metal oxide; 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.
2. The process of claim 1 , wherein the air supplied is at least 10 m 3 for 10 hour per 1 kg of the lithium transition metal oxide.
3. The process of claim 1 , wherein the step of performing the solid state reaction in air, wherein the air supplied is at least 2 m 3 for 10 hour per 1 kg of the lithium transition metal oxide is done in a reactor.
4. The process of claim 3 , wherein the air is preheated in a heat exchanger before it is entered into the reactor.
5. The process of claim 1 , wherein the step of performing 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.
6. The process of claim 1 , wherein the solid mixed transition metal precursor is mixed hydroxide, mixed carbonate or mixed oxides.
7. The process of claim 6 , wherein the mixed hydroxide has the general formula MOOH, wherein M is Ni, Mn and Co.
8. The process of claim 1 , 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 g of the lithium transition metal oxide to a pH less than 5, the solution being prepared by repeated soaking and decanting of the lithium transition metal oxide.