Method for producing lithium-transition metal mixtures
View Patent ↗The invention relates to a method for producing lithium-transition metal mixtures of general formula Li x (M 1 y M 2 1-y ) n O nz , wherein M 1 represents nickel, cobalt or manganese, M 2 represents chromium, cobalt, iron, manganese, molybdenum or aluminium, and is different from M 1 , n is 2 if M 1 represents manganese and is 1 otherwise, x is comprised between 0.9 and 1.2, y is comprised between 0.5 and 1.0 and z is comprised between 1.9 and 2.1. According to the inventive method, an intimate mixture composed of transition metal compounds containing oxygen and of a lithium compound containing oxygen is calcinated, said mixture being obtained by processing a solid powder transition metal compound with a solution of said lithium compound, and then drying. At least the M 1 compound is used in powder form having a specific surface of at least 20 m 2 /g (BET) and calcination is carried out in a fluidised bed.
1. A process for preparing lithium transition metallates of the general formula
Li x (M 1 y M 2 1-y ) n O nz ,
wherein
M 1 represents nickel, cobalt or manganese,
M 2 represents chromium, cobalt, iron, manganese, molybdenum or aluminium and is not identical to M 1 ,
n is 2 if M 1 is manganese, otherwise 1,
x is a number between 0.9 and 1.2,
y is a number between 0.5 and 1.0 and
z is a number between 1.9 and 2.1,
by calcining an intimate mixture of oxygen-containing transition metal compounds and an oxygen-containing lithium compound, which has been obtained by treating a solid powdered transition metal compound with a solution of the lithium compound and drying, wherein at least the M 1 compound is used in the form of a powder with a specific surface area of at least 10 m 2 /g (BET) and calcination is performed in a moving bed.
2. A process according to claim 1 , wherein the transition metallate is milled and sieved after calcination and the finer fraction from sieving is recycled to the moving bed.
3. A process according to claim 1 wherein a mixed transition metal compound which contains at least some of the M 2 compound is used as the M 1 compound.
4. A process according to claim 1 wherein the solution of lithium compound contains at least some of the M 2 compound.
5. A process according to claim 1 wherein calcination is performed in a rotary kiln, in a fluidised bed or in a fall-shaft reactor (downer).
6. A process according to claim 1 wherein following calcination, milling is performed and, after milling, further calcination is performed in an oxygen-containing atmosphere.
7. A process according to claim 1 wherein LiNO 3 is used as the lithium compound and Ni(OH) 2 is used as the M 1 transition metal compound.
8. A process according to claim 7 , wherein NO 2 released during calcination is recovered as nitric acid and is reacted with LiOH to give LiNO 3 which is used as the lithium compound.
9. A process according to claim 1 wherein the transition metal compound treated with the solution of a lithium compound is dried by spray drying or mixer granulation.