Method for the precipitation of particles of a metal carbonate material without use of a chelating agent
In a method for the precipitation of particles of a metal carbonate material comprising nickel and manganese in an atomic ratio of 0≤Ni:Mn≤1:3, aqueous solutions comprising sulfates or nitrates of nickel and manganese are mixed with aqueous solutions of carbonates or mixtures of carbonates and hydroxides of sodium or potassium in a stirred reactor at pH>7.5 without the use of a chelating agent. Thereby agglomerated particles are formed without any subsequent process steps, in particular no subsequent process at temperatures higher than the precipitation temperature.
1. A method for the precipitation of particles of a metal carbonate material comprising nickel and manganese in an atomic ratio of 0≤Ni:Mn≤1:3, wherein an aqueous solution comprising sulfates of nickel and manganese or an aqueous solution comprising nitrates of nickel and manganese is mixed with an aqueous solution of sodium carbonate or potassium carbonate or a mixture of sodium carbonate and sodium hydroxide or a mixture of potassium carbonate and potassium hydroxide in a stirred reactor at pH>7.5 without the use of a chelating agent, thereby forming agglomerated particles in one precipitation step without any subsequent process steps to change the shapes of the agglomerated particles before use of the agglomerated particles as a precursor for the preparation of a lithium-ion battery positive electrode material, wherein the agglomerated particles are characterized by an average circularity higher than 0.90 and simultaneously an average aspect ratio lower than 1.50.
2. Method according to claim 1 , wherein the aqueous solution comprising sulfates of nickel and manganese or the aqueous solution comprising nitrates of nickel and manganese is contained in a first vessel, and the aqueous solution of sodium carbonate or potassium carbonate or the mixture of sodium carbonate and sodium hydroxide or the mixture of potassium carbonate and potassium hydroxide is contained in a second vessel, and the mixing thereof takes place in a stirred reactor.
3. Method according to claim 1 , wherein the aqueous solution comprising sulfates of nickel and manganese or the aqueous solution comprising nitrates of nickel and manganese is mixed with the aqueous solution of sodium carbonate or potassium carbonate.
4. Method according to claim 1 , wherein the agglomerated particles are essentially spherical.
5. Method according to claim 1 , wherein the Ni:Mn atomic ratio in the metal carbonate material is 1/4≤Ni:Mn≤1/3.
6. Method according to claim 1 , wherein the pH in the stirred reactor is 7.5<pH<12.0.
7. Method according to claim 1 , wherein D50 of the precipitate is between 3 and 50 μm, where D50 of a volume-based particle size distribution is defined as the median particle size.
8. Method according to claim 7 , wherein the distribution of the agglomerate size of the precipitate is characterized in that the ratio between D90 and D10 is smaller than or equal to 4, wherein D10 is the particle size where 10% of the volume of the population lies below the value of D10, and D90 is the particle size where 90% of the volume of the population lies below the value of D90.
9. Method according to claim 1 , wherein the agglomerated particles are subjected to growth and polishing in a stirred reactor.
10. Method according to claim 9 , where the stirred reactor comprises of two or more stirred sub-reactors connected in series.
11. Method according to claim 1 , wherein the precipitate is used as a precursor for the preparation of lithium-ion battery positive electrode materials.
12. Method according to claim 1 , wherein the precipitate is used as a precursor for the preparation of lithium nickel manganese oxide-type (LNMO) lithium-ion battery positive electrode materials.
13. Method according to claim 1 , wherein the particles are of the formula Ni y Mn 2-y (CO 3 ) 2 , wherein 0≤y≤0.5.