High voltage lithium nickel cobalt manganese oxide precursor, method for making the same, and high voltage lithium nickel cobalt manganese oxide cathode material

Abstract

A high voltage lithium nickel cobalt manganese oxide precursor is provided in the present disclosure. Primary particles of the lithium nickel cobalt manganese oxide precursor are in a clustered “petals” configuration. The “petal” has a sheet shape. A secondary particle of the lithium nickel cobalt manganese oxide precursor has a spherical structure with a loosened interior. A method for making the high voltage lithium nickel cobalt manganese oxide precursor is further provided in the present disclosure. In the method, through the unique design of the reaction atmosphere in combination with advantages of high-low pH phase separation as well as the appropriate matching between the output power and flow rates, the lithium nickel cobalt manganese oxide precursor having “petal-like” and sheet shaped primary particles and spherical and porous secondary particles is made. Compared to the conventional precursor, the primary particle of the present precursor has a unique structure and the secondary particle of the present precursor has a loosened and porous interior, which provide an important guiding significance for a morphology study of small particle sized lithium nickel cobalt manganese oxide precursor and a preparation process optimization. A high voltage lithium nickel cobalt manganese oxide cathode material made from the nickel cobalt manganese oxide precursor has a single-crystal structure.

Claims

1. A lithium nickel cobalt manganese oxide precursor, comprising secondary particles, wherein each secondary particle is composed of primary particles, the primary particles of the lithium nickel cobalt manganese oxide precursor are petals in a clustered configuration, the petal has a sheet shape, and the secondary particle of the lithium nickel cobalt manganese oxide precursor has a spherical structure with a loosened interior, wherein the lithium nickel cobalt manganese oxide precursor has a tap density of 1 to 1.5 g/cm.sup.3, a specific surface area of 8 to 20 m.sup.2/g, an apparent density of 0.6 to 1 g/cm.sup.3, and a sulfur content of 0.12% to 0.2%.

2. The lithium nickel cobalt manganese oxide precursor of claim 1, wherein the sheet shaped petal has a length of 400 nm to 800 nm and a thickness of 50 nm to 100 nm.

3. The lithium nickel cobalt manganese oxide precursor of claim 1, wherein particle sizes of the secondary particles are as follows: D10 is not smaller than 1.5 μm D50 is from 3 μm to 4 μm, and D90 is not greater than 8 μm; and the secondary particles have a particle size distribution of (D90−D10)/D50<1.

4. The lithium nickel cobalt manganese oxide precursor of claim 1, wherein the lithium nickel cobalt manganese oxide precursor has a molecular formula of Ni.sub.xCo.sub.yMn.sub.z(OH).sub.2, x+y+z=1, 0.5≤x≤0.9, 0<y≤0.2, and 0<z≤0.2, Ni and Co are both in a valence state of +2 in the lithium nickel cobalt manganese oxide precursor, and Mn is in mixed valence states of +2, +3, and +4 in the lithium nickel cobalt manganese oxide precursor.

5. A method for making the lithium nickel cobalt manganese oxide precursor of claim 1, comprising steps of: (1) preparing a soluble mixed salt water solution according to a stoichiometric ratio of Ni.sub.xCo.sub.yMn.sub.z(OH).sub.2, a total concentration of metal ions in the solution is 1 to 2 mol/L, wherein x+y+z=1, 0.5≤x≤0.9, 0<y≤0.2, and 0<z≤0.2; (2) adding an ammonia solution into a reaction kettle as a reaction base solution, controlling an ammonia concentration in the reaction base solution to be 2 to 6 g/L, and regulating a pH value of the reaction base solution to 12 to 13; (3) introducing high purity nitrogen gas into the reaction kettle while starting a stirrer of the reaction kettle, feeding the soluble mixed salt water solution prepared in the step (1), a strong alkali solution, and an ammonia solution simultaneously into the reaction kettle to have a reaction, and maintaining a pH value of the reaction system between 12 and 13 throughout whole reaction process of the step (3); (4) terminating the feeding of the strong alkali solution and the introducing of the high purity nitrogen gas, keeping the feeding of the soluble mixed salt water solution and the ammonia solution to reduce the pH value of the reaction system to 11 to 12 to keep the reaction; and (5) obtaining a qualified material overflowed from the reaction kettle after the reaction, thereby obtaining the lithium nickel cobalt manganese oxide precursor.

6. The method of claim 5, wherein in the step (3), the ammonia solution has a concentration of 10 to 13 mol/L, and the strong alkali solution is a sodium hydroxide solution with a concentration of 6 to 8 mol/L.

7. The method of claim 5, wherein in the step (3), the high purity nitrogen gas is nitrogen gas with a purity of 99.999%; a stirring frequency of the stirrer is 40 to 50 Hz; a feed flow rate of the soluble mixed salt water solution is 1.5 to 4 L/h; a feed flow rate of the ammonia solution is 0.4 to 0.8 L/h, and the ammonia concentration in the reaction system is kept 4 to 6 g/L throughout the whole reaction process of the step (3); a reaction temperature is 30° C. to 40° C.; the feeding of the strong alkali solution and the introducing of the high purity nitrogen gas are terminated after feeding continuously for 2 to 3 hours in the step (3).

8. The method of claim 5, wherein the reaction is continuously carried out in the step (4) for at least 20 hours.

9. The method of claim 5, wherein the step (5) further comprises ageing, filtering under pressure, washing, drying, and sieving the qualified material overflowed from the reaction kettle.

10. The method of claim 9, wherein in the step (5), the washing process comprises: firstly adding the material in a sodium hydroxide solution with a concentration of 6 to 8 mol/L to wash, keeping a temperature for the washing to be 60° C. to 70° C., and then adding the material into pure water to wash, until a pH value of the used water is smaller than 10; and the drying comprises: drying the material at 110° C. until a water content of the material is not greater than 1%; the sieving comprises: sieving the material by using a 325 mesh sieve.

11. The method of claim 10, wherein the washing is terminated when the pH value of the used water is smaller than 9.5.

12. The method of claim 5, wherein in the step (2), the ammonia concentration in the reaction base solution is 2 to 4 g/L, and the pH value of the reaction base solution is 12.5 to 12.6.

13. The method of claim 5, wherein in the step (4), the pH value of the reaction system is controlled within the range from 11.8 to 11.9.

14. The method of claim 5, wherein in the step (5), the qualified material comprises a target particle diameter D50 of 3 to 4 μm.

15. A method for making a lithium nickel cobalt manganese oxide precursor, comprising steps of: (1) preparing a soluble mixed salt water solution according to a stoichiometric ratio of Ni.sub.xCo.sub.yMn.sub.z(OH).sub.2, a total concentration of metal ions in the solution is 1 to 2 mol/L, wherein x+y+z=1, 0.5≤x≤0.9, 0<y≤0.2, and 0<z≤0.2; (2) adding an ammonia solution into a reaction kettle as a reaction base solution, controlling an ammonia concentration in the reaction base solution to be 2 to 6 g/L, and regulating a pH value of the reaction base solution to 12 to 13; (3) introducing high purity nitrogen gas into the reaction kettle while starting a stirrer of the reaction kettle, feeding the soluble mixed salt water solution prepared in the step (1), a strong alkali solution, and an ammonia solution simultaneously into the reaction kettle to have a reaction, and maintaining a pH value of the reaction system between 12 and 13 throughout whole reaction process of the step (3), wherein in the step (3), the high purity nitrogen gas is nitrogen gas with a purity of 99.999%; a stirring frequency of the stirrer is 40 to 50 Hz; a feed flow rate of the soluble mixed salt water solution is 1.5 to 4 L/h; a feed flow rate of the ammonia solution is 0.4 to 0.8 L/h, and the ammonia concentration in the reaction system is kept 4 to 6 g/L throughout the whole reaction process of the step (3); a reaction temperature is 30° C. to 40° C.; the feeding of the strong alkali solution and the introducing of the high purity nitrogen gas are terminated after feeding continuously for 2 to 3 hours in the step (3); (4) terminating the feeding of the strong alkali solution and the introducing of the high purity nitrogen gas, keeping the feeding of the soluble mixed salt water solution and the ammonia solution to reduce the pH value of the reaction system to 11 to 12 to keep the reaction; and (5) obtaining a qualified material overflowed from the reaction kettle after the reaction, thereby obtaining a lithium nickel cobalt manganese oxide precursor comprising secondary particles, wherein each secondary particle is composed of primary particles, the primary particles of the lithium nickel cobalt manganese oxide precursor are petals in a clustered configuration, the petal has a sheet shape, and the secondary particle of the lithium nickel cobalt manganese oxide precursor has a spherical structure with a loosened interior.

16. A method for making a lithium nickel cobalt manganese oxide precursor, comprising steps of: (1) preparing a soluble mixed salt water solution according to a stoichiometric ratio of Ni.sub.xCo.sub.yMn.sub.z(OH).sub.2, a total concentration of metal ions in the solution is 1 to 2 mol/L, wherein x+y+z=1, 0.5≤x≤0.9, 0<y≤0.2, and 0<z≤0.2; (2) adding an ammonia solution into a reaction kettle as a reaction base solution, controlling an ammonia concentration in the reaction base solution to be 2 to 6 g/L, and regulating a pH value of the reaction base solution to 12 to 13; (3) introducing high purity nitrogen gas into the reaction kettle while starting a stirrer of the reaction kettle, feeding the soluble mixed salt water solution prepared in the step (1), a strong alkali solution, and an ammonia solution simultaneously into the reaction kettle to have a reaction, and maintaining a pH value of the reaction system between 12 and 13 throughout whole reaction process of the step (3); (4) terminating the feeding of the strong alkali solution and the introducing of the high purity nitrogen gas, keeping the feeding of the soluble mixed salt water solution and the ammonia solution to reduce the pH value of the reaction system to 11 to 12 to keep the reaction; and (5) obtaining a qualified material overflowed from the reaction kettle after the reaction, thereby obtaining a lithium nickel cobalt manganese oxide precursor, wherein the step (5) further comprises ageing, filtering under pressure, washing, drying, and sieving the qualified material overflowed from the reaction kettle, wherein in the step (5), the washing process comprises: firstly adding the material in a sodium hydroxide solution with a concentration of 6 to 8 mol/L to wash, keeping a temperature for the washing to be 60° C. to 70° C., and then adding the material into pure water to wash, until a pH value of the used water is smaller than 10; and the drying comprises: drying the material at 110° C. until a water content of the material is not greater than 1%; the sieving comprises: sieving the material by using a 325 mesh sieve, and wherein the lithium nickel cobalt manganese oxide precursor comprises secondary particles, wherein each secondary particle is composed of primary particles, the primary particles of the lithium nickel cobalt manganese oxide precursor are petals in a clustered configuration, the petal has a sheet shape, and the secondary particle of the lithium nickel cobalt manganese oxide precursor has a spherical structure with a loosened interior.

17. The method of claim 16, wherein the washing is terminated when the pH value of the used water is smaller than 9.5.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a particle size distribution diagram of Ni.sub.0.6Co.sub.0.2Mn.sub.0.2(OH).sub.2 particles made in Example 1 of the present disclosure.

(2) FIG. 2 is an image of the Ni.sub.0.6Co.sub.0.2Mn.sub.0.2(OH).sub.2 particles made in Example 1 of the present disclosure observed under 50000-times electron microscope.

(3) FIG. 3 is an image of the Ni.sub.0.6Co.sub.0.2Mn.sub.0.2(OH).sub.2 particles made in Example 1 of the present disclosure observed under 30000-times electron microscope.

(4) FIG. 4 is an image of the Ni.sub.0.2Co.sub.0.2Mn.sub.0.2(OH).sub.2 particles made in Example 1 of the present disclosure observed under 5000-times electron microscope.

(5) FIG. 5 is an image showing a morphology of a lithium nickel cobalt manganese oxide cathode material made in Example 1 of the present disclosure.

(6) FIG. 6 is a particle size distribution diagram of Ni.sub.0.6Co.sub.0.2Mn.sub.0.2(OH).sub.2 particles made in Comparative Example 1 of the present disclosure.

(7) FIG. 7 is an image of the Ni.sub.0.6Co.sub.0.2Mn.sub.0.2(OH).sub.2 particles made in Comparative Example 1 of the present disclosure observed under 50000-times electron microscope.

(8) FIG. 8 is an image of the Ni.sub.0.6Co.sub.0.2Mn.sub.0.2(OH).sub.2 particles made in Comparative Example 1 of the present disclosure observed under 20000-times electron microscope.

(9) FIG. 9 is an image of the Ni.sub.0.6Co.sub.0.2Mn.sub.0.2(OH).sub.2 particles made in Comparative Example 1 of the present disclosure observed under 5000-times electron microscope.

(10) FIG. 10 is an image showing a morphology of a lithium nickel cobalt manganese oxide cathode material made in Comparative Example 1 of the present disclosure.

(11) FIG. 11 is a particle size distribution diagram of Ni.sub.0.6Co.sub.0.2Mn.sub.0.2(OH).sub.2 particles made in Example 2 of the present disclosure.

(12) FIG. 12 is an image of the Ni.sub.0.6Co.sub.0.2Mn.sub.0.2(OH).sub.2 particles made in Example 2 of the present disclosure observed under 50000-times electron microscope.

(13) FIG. 13 is an image of the Ni.sub.0.6Co.sub.0.2Mn.sub.0.2(OH).sub.2 particles made in Example 2 of the present disclosure observed under 20000-times electron microscope.

(14) FIG. 14 is an image of the Ni.sub.0.6Co.sub.0.2Mn.sub.0.2(OH).sub.2 particles made in Example 2 of the present disclosure observed under 5000-times electron microscope.

(15) FIG. 15 is an image showing a morphology of a lithium nickel cobalt manganese oxide cathode material made in Example 2 of the present disclosure.

DETAILED DESCRIPTION

(16) A more comprehensive and detailed description with reference to the drawings and preferred embodiments will be made below to better understand the present disclosure. However, the protection scope of the present disclosure is not limited to the specific embodiments below.

(17) Unless expressly defined otherwise, all the terms used herein should be interpreted to have the same meaning as those commonly understood by the person skilled in the art. The terms used herein is merely to describe the specific embodiments of the present disclosure, and is not intended to limit the scope of the present disclosure.

(18) Unless expressly specified otherwise, various raw materials, reagents, instruments, and apparatuses used herein are all commercially available or can be prepared by existing methods

EXAMPLE 1

(19) A high voltage lithium nickel cobalt manganese oxide precursor, with a molecular formula of Ni.sub.0.6 Co.sub.0.2Mn.sub.0.2(OH).sub.7, is provided in the present disclosure. In the lithium nickel cobalt manganese oxide precursor, Ni and Co are both in a valence state of +2, and Mn is in a mixed valence state of +2, +3, and +4. Primary particles of the lithium nickel cobalt manganese oxide precursor are in a clustered “petals” configuration. The “petal” has a sheet shape. The primary particle sheet (i.e. the sheet shaped petal) has a length of about 500 nm and a thickness of about 80 nm (see FIG. 2). A secondary particle has a spherical structure with a loosened interior (see FIGS. 2-4). It can be seen from the microscopic inner structure that the primary particle has a petaloid shape; and the interior of the secondary structure is loosened and porous. Particle sizes of the secondary particles are as follows: D10=2.537 μm, D50=3.640 μm, and D90=5.221 μm (see FIG. 1). A particle size distribution of the secondary particles satisfies (D90−D10)/D50<1. The high voltage lithium nickel cobalt manganese oxide precursor has a tap density of 1.18 g/cm.sup.3, a specific surface area of 9.37 m.sup.2/g, an apparent density of 0.79 g/cm.sup.3, and a sulfur content of 0.18%.

(20) The method for making the high voltage lithium nickel cobalt manganese oxide precursor in the present example includes the following steps:

(21) (1) preparing a soluble metal mixed salt water solution from nickel sulfate, cobalt sulfate, and manganese sulfate according to a molar ratio of metal elements in the chemical formula Ni.sub.0.6Co.sub.0.2Mn.sub.0.2(OH).sub.2, a total concentration of metal ions in the solution is 1.5 mol/L;

(22) and preparing a sodium hydroxide solution with a concentration of 8 mol/L and an ammonia solution with a concentration of 10 mol/L;

(23) (2) adding an ammonia solution with a concentration of 10 mol/L into a 50 L reaction kettle as a base solution of the reaction kettle, controlling the concentration of the ammonia solution in the reaction kettle base solution to be 3.5 g/L, and then pumping a sodium hydroxide solution with a concentration of 8 mol/L into the reaction kettle by a peristaltic pump to regulate a pH value of the reaction kettle base solution to 12.6; and having a stirring paddle of a stirrer of the reaction kettle immersed by the reaction kettle base solution;

(24) (3) introducing high purity nitrogen gas with a concentration of 99.999% into the reaction kettle after the step (2) while starting the stirrer of the reaction kettle, a stirring revolution speed of the stirrer is set to 50 Hz;

(25) (4) feeding the soluble metal mixed salt water solution, the sodium hydroxide solution, and the ammonia solution prepared in the step (1) into the reaction kettle in parallel flows by peristaltic pumps, stirring and reacting; throughout the reaction under stirring, a temperature in the reaction kettle is controlled to be 40° C., a feed flow rate of the soluble metal mixed salt water solution is controlled to be 1.8 L/h, and a feed flow rate of the ammonia solution is controlled to be 0.5 L/h; a pH value of the reaction system is controlled to be 12.6 throughout the reaction by controlling a feed flow rate of the sodium hydroxide solution;

(26) (5) feeding continuously for 3 hours, then reducing the flow rate of the alkali pump to zero while closing an inlet of the nitrogen gas to reduce the pH value of the reaction system to 11.9, keeping feeding the soluble metal mixed salt water solution and the ammonia solution to keep the reaction (a reaction time is 2.0 hours); increasing an ammonia content of the reaction system through the ammonia pump to 4.5 g/L; measuring sizes of particles in the slurry once every 2 hours by a laser particle size analyzer in the reaction process during which fine particles produced in the reaction are gradually grown, and sphericity of the fine particles are gradually improved with the continuous feeding during the reaction; collecting qualified material when it is detected that the particle sizes of secondary particles or aggregations in the reaction kettle reach the target particle sizes: D50=3 to 4 μm; having the qualified material overflowed into an ageing kettle to age the qualified material, and reserving the unqualified material as seed crystals to be used in the next production (next high voltage lithium nickel cobalt manganese oxide precursor production);

(27) (6) removing an upper clear liquid after ageing for 2.5 hours; filtering under pressure by using a plate-frame press machine after the ageing is terminated, and adding a sodium hydroxide solution with a concentration of 6 mol/L to wash the material with alkaline, and controlling a temperature of the washing liquid to be 60° C. to 70° C.;

(28) (7) after the alkaline wash, washing the material with pure water until a pH value of the used water is smaller than 9.5, then drying the washed material at 110° C., and sieving the dried material by using a 325 mesh sieve, thereby obtaining the high voltage lithium nickel cobalt manganese oxide precursor;

(29) (8) mixing lithium carbonate with the lithium nickel cobalt manganese oxide precursor in a molar ratio of 1.05:1 uniformly in a high speed mixer, and sintering the mixture in an oxygen atmosphere at a temperature of 930° C. for 12 hours, thereby obtaining a lithium nickel cobalt manganese oxide cathode material.

(30) FIG. 5 shows a morphology of the lithium nickel cobalt manganese oxide cathode material. The lithium nickel cobalt manganese oxide cathode material has a single-crystal structure. A battery is made by using the lithium nickel cobalt manganese oxide cathode material. An electrochemical performance of the battery is shown in Table 1.

COMPARATIVE EXAMPLE 1

(31) A high voltage lithium nickel cobalt manganese oxide precursor in the present comparative example was made by a method including the following steps:

(32) (1) preparing a soluble metal mixed salt water solution according to a molar ratio of metal elements in the chemical formula of Ni.sub.0.6Co.sub.0.2Mn.sub.0.2(OH).sub.2, a total concentration of metal ions in the solution is 1.5 mol/L; and preparing a sodium hydroxide solution with a concentration of 8 mol/L and an ammonia solution with a concentration of 10 mol/L;

(33) (2) adding an ammonia solution into a 50 L reaction kettle as a base solution of the reaction kettle, controlling the concentration of the ammonia solution in the reaction kettle base solution to be 3.5 g/L, and then pumping a sodium hydroxide solution with a concentration of 8 mol/L into the reaction kettle by a peristaltic pump to regulate a pH value of the reaction kettle base solution to be 12.6; and having a stirring paddle of a stirrer of the reaction kettle immersed by the reaction kettle base solution;

(34) (3) introducing 99.999% nitrogen gas into the reaction kettle after the step 2) while starting the stirrer of the reaction kettle, a stirring revolution speed of the stirrer is set to 50 Hz;

(35) (4) feeding the soluble metal mixed salt water solution, the sodium hydroxide solution, and the ammonia solution prepared in the step (1) into the reaction kettle in parallel flows by peristaltic pumps, stirring and reacting; throughout the reaction under stirring, a temperature in the reaction kettle is controlled to be 40° C., a feed flow rate of the soluble metal mixed salt water solution is controlled to be 1.8 L/h, and a feed flow rate of the ammonia solution is controlled to be 0.3 L/h; a pH value of the reaction system is controlled to be 11.9 throughout the reaction by controlling a feed flow rate of the sodium hydroxide solution;

(36) (5) measuring sizes of particles in the slurry once every 2 hours by a laser particle size analyzer in the reaction process during which fine particles produced in the reaction are gradually grown, and sphericity of the fine particles are gradually improved with the continuous feeding during the reaction; collecting qualified material when it is detected that the particle sizes of secondary particles or aggregations in the reaction kettle reach the target particle sizes: D50=3 to 4 μm; having the qualified material overflowed into an ageing kettle to age the qualified material, and reserving the unqualified material as seed crystals to be used in the next production;

(37) (6) removing an upper clear liquid after ageing for 2.5 hours; filtering under pressure by using a plate-frame press machine after the ageing is terminated, and adding a sodium hydroxide solution with a concentration of 6 mol/L to wash the material with alkaline, while controlling a temperature of the washing liquid to be 60° C. to 70° C.;

(38) (7) after the alkaline wash, washing the material with pure water until a pH value of the used water is smaller than 9.5, then drying the washed material at 110° C., and sieving the dried material by using a 325 mesh sieve, thereby obtaining Ni.sub.0.6Co.sub.0.2Mn.sub.0.2(OH).sub.7 of the present comparative example;

(39) (8) mixing lithium carbonate with the lithium nickel cobalt manganese oxide precursor in a molar ratio of 1.05:1 uniformly in a high speed mixer, and sintering the mixture in an oxygen atmosphere at a temperature of 950° C. for 12 hours, thereby obtaining a lithium nickel cobalt manganese oxide cathode material.

(40) FIG. 6 shows a particle size distribution of Ni.sub.0.6Co.sub.0.2Mn.sub.0.2(OH).sub.2 made in the present comparative example. The primary particles have an average particle size of 600 nm and a thickness of 200 nm. D10=2.111 μm, D50=3.442 μm, and D90=5.610 μm. A tap density is 1.56 g/cm.sup.3. An apparent density is 1.2 g/cm.sup.3. A sulfur content is 0.16%. A specific surface area is 5.6 m.sup.2/g. FIGS. 7-9 are electron microscope photographs of Ni.sub.0.6Co.sub.0.2Mn.sub.0.2(OH).sub.2 made in the present comparative example. As shown in FIGS. 7-9, the primary particles of the precursor have a plate shape, and the secondary particles of the precursor having bumps are seriously aggregated.

(41) FIG. 10 shows a morphology of the lithium nickel cobalt manganese oxide cathode material made in the present comparative example. A battery is made by using the lithium nickel cobalt manganese oxide cathode material. An electrochemical performance of the battery is shown in Table 1.

EXAMPLE 2

(42) A high voltage lithium nickel cobalt manganese oxide precursor, with a molecular formula of Ni.sub.0.6Co.sub.0.2Mn.sub.0.2(OH).sub.2, is provided in the present disclosure. In the lithium nickel cobalt manganese oxide precursor, Ni and Co are both in a valence state of +2, and Mn is in a mixed valence state of +2, +3, and +4. Primary particles of the lithium nickel cobalt manganese oxide precursor are in a clustered “petals” configuration. The “petal” has a sheet shape. Primary particle sheet has a length of 400 nm and a thickness of 100 nm (see FIG. 12). A secondary particle has a spherical structure with a loosened interior. It can be seen from the microscopic inner structure that the primary particle has a petaloid shape; and the secondary particle has a loosened and porous interior (see FIGS. 12-14). Particle sizes of the secondary particles are as follows: D10=2.180 μm, D50=3.472 μm, and D90=5.848 μm (see FIG. 11). A particle size distribution of the secondary particles satisfies (D90−D10)/D50<1. The high voltage lithium nickel cobalt manganese oxide precursor has a tap density of 1.15 g/cm.sup.3, a specific surface area of 12.69 m.sup.2/g, an apparent density of 0.9 g/cm.sup.3, and a sulfur content of 0.17%.

(43) The method for making the high voltage lithium nickel cobalt manganese oxide precursor in the present example includes the following steps:

(44) (1) preparing a soluble metal mixed salt water solution from nickel sulfate, cobalt sulfate, and manganese sulfate according to a molar ratio of metal elements in the chemical formula Ni.sub.0.6Co.sub.0.2Mn.sub.0.2(OH).sub.2, a metal ion total concentration of 1.8 mol/L;

(45) and preparing a sodium hydroxide solution with a concentration of 6 mol/L and an ammonia solution with a concentration of 10 mol/L;

(46) (2) adding an ammonia solution with a concentration of 10 mol/L into a 50 L reaction kettle as a base solution of the reaction kettle, controlling the concentration of the ammonia solution in the reaction kettle base solution to be 3 g/L, and then pumping a sodium hydroxide solution with a concentration of 6 mol/L into the reaction kettle by a peristaltic pump to regulate a pH value of the reaction kettle base solution to be 12.5; and having a stirring paddle of a stirrer of the reaction kettle immersed by the reaction kettle base solution;

(47) (3) introducing high purity nitrogen gas with a purity of 99.999% into the reaction kettle after the step (2), while starting the stirrer of the reaction kettle, a stirring revolution speed of the stirrer is set to 50 Hz;

(48) (4) feeding the soluble metal mixed salt water solution, the sodium hydroxide solution, and the ammonia solution prepared in the step (1) into the reaction kettle in parallel flows by peristaltic pumps, stirring and reacting; throughout the reaction under stirring, a temperature in the reaction kettle is controlled to be 40° C., a feed flow rate of the soluble metal mixed salt water solution is controlled to be 2 L/h, and a feed flow rate of the ammonia solution is controlled to be 0.6 L/h; a pH value of the reaction system is controlled to be 12.5 throughout the reaction;

(49) (5) feeding continuously for 3 hours, then reducing the flow rate of the alkali pump to zero while closing an inlet of the nitrogen gas to reduce the pH value of the reaction system to 11.8, increasing an ammonia content of the reaction system through the ammonia pump to 4 g/L; measuring sizes of particles in the slurry once every 2 hours by a laser particle size analyzer in the reaction process during which fine particles produced in the reaction are gradually grown, and sphericity of the fine particles are gradually improved with the continuous feeding during the reaction; collecting qualified material when it is detected that the particle sizes of secondary particles or aggregations in the reaction kettle reach target particle sizes: D50=3 to 4 μm (reacting for 16 to 18 hours); having the qualified material overflowed into an ageing kettle to age the qualified material, and reserving the unqualified material as seed crystals to be used in the next production;

(50) (6) removing an upper clear liquid after ageing for 2.5 hours; filtering under pressure by using a plate-frame press machine after the ageing is terminated, and adding a sodium hydroxide solution with a concentration of 6 mol/L to wash the material with alkaline, and controlling a temperature of the washing liquid to be 60° C. to 70° C.;

(51) (7) after the alkaline wash, washing the material with pure water until a pH value of the used water is smaller than 9.5, then drying the washed material at 110° C., and sieving the dried material by using a 325 mesh sieve, thereby obtaining the high voltage lithium nickel cobalt manganese oxide precursor;

(52) (8) mixing lithium carbonate with the lithium nickel cobalt manganese oxide precursor in a molar ratio of 1.05:1 uniformly in a high speed mixer, and sintering the mixture in an oxygen atmosphere at a temperature of 930° C. for 12 hours, thereby obtaining a lithium nickel cobalt manganese oxide cathode material.

(53) FIG. 15 shows a morphology of the lithium nickel cobalt manganese oxide cathode material. The lithium nickel cobalt manganese oxide cathode material has a single-crystal structure. battery is made by using the lithium nickel cobalt manganese oxide cathode material. An electrochemical performance of the battery is shown in Table 1.

(54) TABLE-US-00001 TABLE 1 electrochemical performances of batteries made from lithium nickel cobalt manganese oxides of examples and comparative example first discharge capacity capacity mAh/g retention % (discharge at rate after 50 cycles 0.2 C. at normal capability (charging temperature, (2 C./ and voltage range: 0.2 C.) discharge 3-4.35 V) % at 1 C.) Example 1 182 94 95 Example 2 180 93.8 94 Comparative 175 92 91 example 1