Composition comprising lithium compound and mixed metal hydroxides and their preparation and use
View Patent ↗The present invention relates to a particulate mixed metal hydroxide that includes nickel, cobalt and aluminium. The powder particles have a core of nickel/cobalt hydroxide, and a surface that is coated with amorphous aluminium hydroxide. A process for the continuous preparation of such mixed metal hydroxides is also described. The process includes precipitating aluminium hydroxide in the presence of a nickel/cobalt mixed hydroxide in a tube reactor. The mixed metal hydroxides of the present invention may be used to prepare active materials for positive electrodes of a secondary battery.
1. A composition comprising a lithium compound and a mixed metal hydroxide of comprising nickel, cobalt, and aluminum, wherein the mixed metal hydroxide has a particulate form comprising powder particles, and the powder particles have a core and a surface, said core of said powder particles comprising nickel/cobalt hydroxide, and said surface of said powder particles being coated with amorphous aluminum hydroxide,
said mixed metal hydroxide prepared by precipitating aluminum hydroxide in the presence of cobalt-containing nickel hydroxide, by means of:
a) feeding continuously into a tube reactor, an aqueous suspension of cobalt-containing nickel hydroxide, and an aqueous solution of an alkali metal aluminate, thereby forming a mixture of said aqueous suspension of cobalt-containing nickel hydroxide and said aqueous solution of said alkali metal, and
b) neutralizing the mixture of said aqueous suspension and said aqueous solution as it flows through said tube reactor, thereby converting the alkali metal aluminate into aluminum hydroxide, wherein said composition is a precursor of an active material for preparing positive electrode of a secondary battery.
2. The composition of claim 1 wherein said composition is calcined in an oxygen-containing atmosphere at a temperature of from 450 to 900° C.
3. The composition of claim 1 wherein said composition is calcined in an 50 to 93 mol % Ni, 5 to 30 mol % Co, and 2 to 20 mol % Al, the mole percents in each case being based on the total moles of Ni, Co and Al.