Lithium nickel cobalt manganese oxide positive electrode material and preparation method and application thereof

Abstract

The invention discloses a nickel cobalt lithium manganate positive electrode material as well as a preparation method and application thereof, and relates to the technical field of lithium ion batteries. The preparation method of the nickel cobalt lithium manganate positive electrode material comprises the following steps: S1, mixing a lithium salt, a nickel salt, a cobalt salt, a manganese salt and water to obtain a metal salt solution; s2, mixing the metal salt solution with a compound containing amino and carboxyl, and adjusting the pH value to 7.2-8.5 to obtain a mixed solution; s3, heating and stirring the mixed solution to obtain a nickel cobalt lithium manganate precursor; and S4, sequentially carrying out first sintering treatment and second sintering treatment on the precursor to obtain the nickel cobalt lithium manganate positive electrode material. Metal elements in the nickel cobalt lithium manganate positive electrode material prepared by the preparation method are uniformly distributed, and the nickel cobalt lithium manganate positive electrode material has high capacity and excellent cycle performance.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion batteries, and in particular to a nickel-cobalt-manganese-oxide lithium positive electrode material and a preparation method and application thereof. Background Art

[0002] Lithium-ion batteries are widely used in electronic equipment, electric vehicles and other fields due to their advantages such as environmental protection, high operating voltage and light weight. With the development of electronic equipment and electric vehicles, higher requirements are also placed on the capacity of lithium-ion batteries. The positive electrode material is an important component of lithium-ion batteries, and its performance directly affects the electrochemical performance of lithium-ion batteries.

[0003] Compared with lithium nickel oxide and lithium manganese oxide, ternary cathode materials have the advantages of high specific capacity and high safety. 0.33 Co 0.33 Mn 0.33 O2、LiNi 0.5 Co 0.2 Mn 0.3 O2、LiNi 0.8 Co 0.1 Mn 0.1 O2, as the nickel content increases, the material capacity will also increase, but at the same time, the cation mixing phenomenon will become more and more serious, the metal elements will be unevenly distributed, and the first coulombic efficiency and cycle performance will gradually deteriorate. Summary of the invention

[0004] The main purpose of the present invention is to provide a nickel cobalt manganese oxide lithium positive electrode material and its preparation method and application, so as to solve the problem in the prior art that nickel cobalt manganese oxide lithium positive electrode material is difficult to achieve both high capacity and excellent cycle performance and first coulombic efficiency.

[0005] In order to achieve the above object, the first aspect of the present invention provides a method for preparing a nickel cobalt manganese oxide positive electrode material, comprising the following steps:

[0006] Step S1, mixing lithium salt, nickel salt, cobalt salt, manganese salt and water to obtain a metal salt solution;

[0007] Step S2, mixing the metal salt solution with the compound containing amino and carboxyl groups, adjusting the pH value to 7.2-8.5, to obtain a mixed solution;

[0008] Step S3, heating and stirring the mixed solution and drying the mixed solution in sequence to obtain a lithium nickel cobalt manganese oxide precursor;

[0009] Step S4, subjecting the nickel cobalt manganese oxide precursor to a first sintering treatment and a second sintering treatment in sequence to obtain a nickel cobalt manganese oxide positive electrode material.

[0010] Furthermore, the molar ratio of the metal ions in the metal salt solution to the compound containing amino groups and carboxyl groups is 1:(1.1-1.3).

[0011] Furthermore, the molar ratio of lithium, nickel, cobalt and manganese in the metal salt solution is (0.9-1.2): (0.5-0.9): (0.08-0.2): (0.08-0.2).

[0012] Furthermore, the temperature of the heating and stirring treatment is 80-120°C, the rotation speed is 60-100r / min, and the time is 6-8h; and / or the temperature of the drying treatment is 250-300°C, and the time is 2-4h; and / or the temperature of the first sintering treatment is 450-550°C, the time is 3-5h, and the heating rate is 1-3°C / min; and / or the temperature of the second sintering treatment is 700-800°C, the time is 8-12h, and the heating rate is 2-4°C / min.

[0013] Furthermore, the sum of the molar concentrations of metal ions in the metal salt solution is 0.1 to 0.3 mol / L.

[0014] Furthermore, after the second sintering process, the second sintered product is ground to a D50 particle size of 2 to 9 μm to obtain a nickel cobalt manganese oxide lithium positive electrode material.

[0015] Further, the compound containing amino and carboxyl groups includes glycine; and / or, the lithium salt includes at least one of lithium acetate and lithium nitrate; and / or, the nickel salt includes at least one of nickel acetate, nickel nitrate and nickel sulfate; and / or, the cobalt salt includes at least one of cobalt acetate, cobalt nitrate and cobalt sulfate; and / or, the manganese salt includes at least one of manganese acetate, manganese nitrate and manganese sulfate.

[0016] The second aspect of the present invention provides a nickel cobalt lithium manganese oxide positive electrode material, which is prepared by the preparation method provided by the first aspect.

[0017] Furthermore, the chemical formula of the positive electrode material of lithium nickel cobalt manganese oxide is Li a Ni b Co c Mn 1-b-c O2, among which, 0.9≤a≤1.2, 0.5≤b≤0.9, 0.08≤c≤0.2.

[0018] A third aspect of the present invention provides a lithium-ion battery comprising the lithium nickel cobalt manganese oxide positive electrode material of the second aspect.

[0019] The implementation of the present invention has at least the following beneficial effects:

[0020] The preparation method of the nickel cobalt manganese oxide positive electrode material provided by the present invention uses a solution combustion method and a compound containing amino groups and carboxyl groups, so that the compound containing amino groups and carboxyl groups is used as both a fuel and a complexing agent for reacting with metal ions, thereby ensuring that the metal ions are evenly dispersed and forming a precursor, and then the nickel cobalt manganese oxide positive electrode material is obtained by two-stage sintering, further ensuring that the metal elements are evenly dispersed, which is conducive to obtaining a nickel cobalt manganese oxide positive electrode material with high capacity, excellent cycle performance and first coulomb efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is an element distribution (Mapping) diagram of the nickel cobalt manganese oxide lithium positive electrode material in Example 1 of the present invention. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0023] As described in the background of the present invention, the prior art has the problem that it is difficult for nickel cobalt manganese oxide lithium positive electrode materials to have both high capacity and excellent cycle performance. In order to solve the above problem, the first aspect of the present invention provides a method for preparing a nickel cobalt manganese oxide lithium positive electrode material, comprising the following steps:

[0024] Step S1, mixing lithium salt, nickel salt, cobalt salt, manganese salt and water to obtain a metal salt solution;

[0025] Step S2, mixing the metal salt solution with the compound containing amino and carboxyl groups, adjusting the pH value to 7.2-8.5, to obtain a mixed solution;

[0026] Step S3, heating and stirring the mixed solution and drying the mixed solution in sequence to obtain a lithium nickel cobalt manganese oxide precursor;

[0027] Step S4, subjecting the nickel cobalt manganese oxide precursor to a first sintering treatment and a second sintering treatment in sequence to obtain a nickel cobalt manganese oxide positive electrode material.

[0028] Specifically, in step S1, lithium salt, nickel salt, cobalt salt and manganese salt are all soluble salts, which are mixed with water, completely dissolved and a metal salt solution is obtained, and the water can be excessive to ensure that the metal salt is fully dissolved. In step S2, by introducing a compound containing amino and carboxyl groups, the compound containing amino and carboxyl groups can be used as a subsequent fuel, and can also be used as a complexing agent for reacting with metal ions. The compound containing amino and carboxyl groups forms a complex with metal ions, which helps the subsequent combustion reaction. The pH value can be adjusted by adding ammonia water. In step S3, by heating and stirring the mixed solution, the water in the solution will gradually evaporate during the heating process, and the compound containing amino and carboxyl groups will react with the metal salt to undergo a combustion reaction, and then after drying, the water and unreacted raw materials are removed to obtain a nickel cobalt manganese oxide lithium precursor. In step S4, by performing a two-stage sintering treatment on the nickel cobalt manganese oxide lithium precursor, it is ensured that the unreacted compounds containing amino and carboxyl groups are removed and the hydroxide precursor is fully converted into oxides to form a nickel cobalt manganese oxide lithium positive electrode material.

[0029] According to the research of the present invention, the nickel cobalt manganese oxide positive electrode material obtained by the above-mentioned preparation method has excellent electrochemical properties. This is because the present invention uses a solution combustion method and a compound containing amino and carboxyl groups to make the compound containing amino and carboxyl groups serve as both a fuel and a chelating agent for reacting with metal ions, thereby ensuring that the metal ions are evenly dispersed and realizing the formation of a precursor. The nickel cobalt manganese oxide positive electrode material is then obtained by two-stage sintering, further ensuring that the metal elements are evenly dispersed, thereby obtaining a nickel cobalt manganese oxide positive electrode material with high capacity, excellent cycle performance and first coulomb efficiency.

[0030] The present invention does not limit the amount of the compound containing amino and carboxyl groups, as long as sufficient compounds containing amino and carboxyl groups react with metal ions. For example, in some embodiments, the molar ratio of metal ions to compounds containing amino and carboxyl groups in the metal salt solution is 1: (1.1-1.3), such as 1: 1.1, 1: 1.2, 1: 1.3 or a range consisting of any two of them. By limiting the molar ratio of metal ions to compounds containing amino and carboxyl groups in the metal salt solution to the above range, it is ensured that the compounds containing amino and carboxyl groups fully react with metal ions, while avoiding the residue caused by excessive compounds containing amino and carboxyl groups, which helps to improve the efficiency of the combustion reaction. Among them, the metal ions in the metal salt solution refer to the sum of the metal ions of lithium salts, nickel salts, cobalt salts and manganese salts.

[0031] The present invention does not limit the amount of lithium salt, nickel salt, cobalt salt and manganese salt added, which can be determined according to the stoichiometric ratio of the desired positive electrode material. In some embodiments, the molar ratio of lithium element, nickel element, cobalt element and manganese element in the metal salt solution is (0.9-1.2): (0.5-0.9): (0.08-0.2): (0.08-0.2).

[0032] The mixed solution is heated and stirred. During the heating process, the water in the solution will gradually evaporate, and the compounds containing amino and carboxyl groups will undergo combustion reactions with the metal salts. During the heating and stirring process, when black flocs are formed, the heating and stirring are stopped, the black flocs are dried, and the incompletely burned combustible fuel is fully burned to finally obtain a nickel cobalt manganese oxide lithium precursor.

[0033] The present invention does not limit the parameters of the heating and stirring treatment, as long as the combustion reaction of the mixed solution is ensured. In some embodiments, the temperature of the heating and stirring treatment is 80 to 120°C, such as 80°C, 90°C, 100°C, 110°C, 120°C or a range consisting of any two thereof, the speed is 60 to 100 r / min, such as 60 r / min, 70 r / min, 80 r / min, 90 r / min, 100 r / min or a range consisting of any two thereof, and the time is 6 to 8 hours. The heating and stirring treatment can be carried out on a heating stirring table.

[0034] The present invention does not limit the specific parameters of the drying process, and the drying process can be carried out in a dryer. In some embodiments, the drying process temperature is 250-300° C. and the time is 2-4 hours. In the specific implementation process of the present invention, the drying process can be carried out in a blast drying oven at 250-300° C. for 3 hours to remove the unreacted raw materials.

[0035] The first sintering treatment is essentially a pre-calcination, which is used to remove moisture, residual amino and carboxyl compounds, and volatile substances in the lithium nickel cobalt manganese oxide precursor, and promote chemical reactions between the raw materials. The temperature of the first sintering treatment is usually low. After the first sintering treatment, the product of the first sintering treatment is cooled to room temperature; the second sintering treatment is essentially a main calcination, which is used to make the raw materials fully react to form the desired positive electrode material. The temperature of the second sintering treatment is higher than that of the first sintering treatment. Different calcination temperatures and times can be selected according to the desired type of positive electrode material. After the second sintering treatment, the product is cooled to room temperature again.

[0036] The present invention does not limit the specific parameters of the first sintering treatment. For example, in some embodiments, the temperature of the first sintering treatment is 450-550°C, such as 450°C, 480°C, 500°C, 520°C, 550°C or any two of them, the time is 3-5h, such as 3h, 4h, 5h or any two of them, and the heating rate is 1-3°C / min, such as 1°C / min, 2°C / min, 3°C / min or any two of them. By limiting the heating rate of the first sintering treatment to the above range, the reaction is ensured to be complete while preventing the material from agglomerating.

[0037] The present invention does not limit the specific parameters of the second sintering treatment. For example, in some embodiments, the temperature of the second sintering treatment is 700-800°C, such as 700°C, 720°C, 750°C, 780°C, 800°C or any two of them, the time is 8-12h, such as 8h, 9h, 10h, 11h, 12h or any two of them, and the heating rate is 2-4°C / min, such as 2°C / min, 3°C / min, 4°C / min or any two of them. By limiting the heating rate of the second sintering treatment to the above range, the reaction is ensured to be complete while preventing the material from agglomerating.

[0038] In some embodiments, the sum of the molar concentrations of metal ions in the metal salt solution is 0.1-0.3 mol / L.

[0039] The product formed by the second sintering treatment may be post-processed as needed, such as crushing, screening, washing, etc., to obtain the desired positive electrode material. For example, in some embodiments, after the second sintering treatment, the second sintering product is also ground to a D50 particle size of 2 to 9 μm to obtain a nickel cobalt manganese oxide positive electrode material. This ensures that the D50 particle size of the nickel cobalt manganese oxide positive electrode material is 2 to 9 μm, such as 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or any two of them.

[0040] The present invention does not limit the specific type of raw materials, as long as the lithium salt, nickel salt, cobalt salt, and manganese salt are all dissolved in water to form a metal salt solution. For example, it can be acetate or nitrate. Specifically, in some embodiments, the compound containing amino and carboxyl groups includes glycine; and / or, the lithium salt includes at least one of lithium acetate and lithium nitrate; and / or, the nickel salt includes at least one of nickel acetate, nickel nitrate, and nickel sulfate; and / or, the cobalt salt includes at least one of cobalt acetate, cobalt nitrate, and cobalt sulfate; and / or, the manganese salt includes at least one of manganese acetate, manganese nitrate, and manganese sulfate.

[0041] The second aspect of the present invention provides a nickel cobalt lithium manganese oxide positive electrode material, which is prepared by the preparation method of the first aspect.

[0042] Since the nickel cobalt manganese oxide lithium positive electrode material is prepared by the above-mentioned specific preparation method, it has both high capacity and excellent cycle performance.

[0043] In some embodiments, the chemical formula of the lithium nickel cobalt manganese oxide positive electrode material is Li a Ni b Co c Mn 1-b-cO2, wherein 0.9≤a≤1.2, 0.5≤b≤0.9, 0.08≤c≤0.2. Preferably, the chemical formula of the nickel cobalt manganese oxide positive electrode material is LiNi 0.8 Co 0.1 Mn 0.1 O2.

[0044] The third aspect of the present invention provides a lithium-ion battery, comprising the lithium nickel cobalt manganese oxide positive electrode material provided in the second aspect.

[0045] Due to the inclusion of the above-mentioned nickel cobalt manganese oxide lithium positive electrode material, the lithium ion battery has excellent capacity and first coulomb efficiency (first efficiency).

[0046] The present invention is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed by the present invention.

[0047] Example 1

[0048] The preparation of the lithium nickel cobalt manganese oxide positive electrode material of this embodiment includes the following steps:

[0049] Step S1, according to LiNi 0.8 Co 0.1 Mn 0.1 The required lithium nitrate 6.895 g, nickel nitrate hexahydrate 23.2632 g, cobalt nitrate hexahydrate 2.9104 g, and manganese nitrate tetrahydrate 2.5101 g are dissolved in ultrapure water in a stoichiometric ratio of 1:100 g to 2:100 g to form a metal salt solution; wherein the molar concentration of the metal ions in the metal salt solution is 0.1 mol / L;

[0050] Step S2, adding glycine to the metal salt solution, and then adding a certain amount of ammonia water, adjusting the pH value of the solution to 8, to obtain a mixed solution; wherein the molar ratio of glycine to the metal ions in the metal salt solution is 1.2:1;

[0051] Step S3, continuously stirring and heating the mixed solution at 100° C. on a magnetic heating stirring table at a stirring speed of 80 r / min until black flocs are generated; treating the mixed solution in a blast drying oven at 280° C. for 3 hours to obtain a nickel cobalt manganese oxide lithium precursor;

[0052] Step S4, heating the lithium nickel cobalt manganese oxide precursor to 500°C in a muffle furnace at a heating rate of 2°C / min, treating for 3 hours, cooling to room temperature, and then heating to 850°C at a heating rate of 5°C / min and calcining for 10 hours to obtain a sintered product; grinding the sintered product in a mortar for 10 minutes until the D50 particle size is 5 μm to obtain a lithium nickel cobalt manganese oxide positive electrode material.

[0053] Example 2

[0054] The preparation of the lithium nickel cobalt manganese oxide positive electrode material of this embodiment includes the following steps:

[0055] Step S1, according to LiNi 0.8 Co 0.1 Mn 0.1 The required lithium nitrate 6.895 g, nickel nitrate hexahydrate 23.2632 g, cobalt nitrate hexahydrate 2.9104 g, and manganese nitrate tetrahydrate 2.5101 g are dissolved in ultrapure water in a stoichiometric ratio of 1:100 g to 2:100 g to form a metal salt solution; wherein the molar concentration of the metal ions in the metal salt solution is 0.1 mol / L;

[0056] Step S2, adding glycine to the metal salt solution, and then adding a certain amount of ammonia water, adjusting the pH value of the solution to 8.5, to obtain a mixed solution; wherein the molar ratio of glycine to the metal ions in the metal salt solution is 1.1:1;

[0057] Step S3, continuously stirring and heating the mixed solution at 100° C. on a magnetic heating stirring table at a stirring speed of 80 r / min until black floccules are generated; treating the mixed solution in a blast drying oven at 250° C. for 3 hours to obtain a nickel cobalt manganese oxide lithium precursor;

[0058] Step S4, heating the lithium nickel cobalt manganese oxide precursor to 500°C in a muffle furnace at a heating rate of 2°C / min, treating for 3 hours, cooling to room temperature, and then heating to 850°C at a heating rate of 5°C / min and calcining for 10 hours to obtain a sintered product; grinding the sintered product in a mortar for 10 minutes until the D50 particle size is 5 μm to obtain a lithium nickel cobalt manganese oxide positive electrode material.

[0059] Example 3

[0060] The preparation of the lithium nickel cobalt manganese oxide positive electrode material of this embodiment includes the following steps:

[0061] Step S1, according to LiNi 0.8 Co 0.1 Mn 0.1 The required lithium nitrate 6.895 g, nickel nitrate hexahydrate 23.2632 g, cobalt nitrate hexahydrate 2.9104 g, and manganese nitrate tetrahydrate 2.5101 g are dissolved in ultrapure water in a stoichiometric ratio of 1:100 g to 2:100 g to form a metal salt solution; wherein the molar concentration of the metal ions in the metal salt solution is 0.1 mol / L;

[0062] Step S2, adding glycine to the metal salt solution, and then adding a certain amount of ammonia water, adjusting the pH value of the solution to 8, to obtain a mixed solution; wherein the molar ratio of glycine to the metal ions in the metal salt solution is 1.3:1;

[0063] Step S3, continuously stirring and heating the mixed solution at 100° C. on a magnetic heating stirring table at a stirring speed of 80 r / min until black floccules are generated; treating the mixed solution in a blast drying oven at 300° C. for 3 hours to obtain a nickel cobalt manganese oxide lithium precursor;

[0064] Step S4, heating the lithium nickel cobalt manganese oxide precursor to 500°C in a muffle furnace at a heating rate of 2°C / min, treating for 3 hours, cooling to room temperature, and then heating to 850°C at a heating rate of 5°C / min and calcining for 10 hours to obtain a sintered product; grinding the sintered product in a mortar for 10 minutes until the D50 particle size is 5 μm to obtain a lithium nickel cobalt manganese oxide positive electrode material.

[0065] Example 4

[0066] The preparation of the lithium nickel cobalt manganese oxide positive electrode material of this embodiment includes the following steps:

[0067] Step S1, according to LiNi 0.8 Co 0.1 Mn 0.1 The required lithium acetate, nickel acetate, cobalt acetate and manganese acetate are dissolved in ultrapure water in a stoichiometric ratio of O2 to form a metal salt solution;

[0068] Step S2, adding glycine to the metal salt solution, and then adding a certain amount of ammonia water, adjusting the pH value of the solution to 8, to obtain a mixed solution; wherein the molar ratio of glycine to the metal ions in the metal salt solution is 1.2:1;

[0069] Step S3, continuously stirring and heating the mixed solution at 100° C. on a magnetic heating stirring table at a stirring speed of 80 r / min until black floccules are generated; treating the mixed solution in a blast drying oven at 250° C. for 3 hours to obtain a nickel cobalt manganese oxide lithium precursor;

[0070] Step S4, heating the lithium nickel cobalt manganese oxide precursor to 500°C in a muffle furnace at a heating rate of 2°C / min, treating for 3 hours, cooling to room temperature, and then heating to 850°C at a heating rate of 5°C / min and calcining for 10 hours to obtain a sintered product; grinding the sintered product in a mortar for 10 minutes until the D50 particle size is 5 μm to obtain a lithium nickel cobalt manganese oxide positive electrode material.

[0071] Comparative Example 1

[0072] The preparation of the nickel cobalt lithium manganese oxide positive electrode material of this comparative example comprises the following steps:

[0073] Step S1, according to LiNi 0.8 Co 0.1 Mn 0.1The required lithium nitrate 6.895 g, nickel nitrate hexahydrate 23.2632 g, cobalt nitrate hexahydrate 2.9104 g, and manganese nitrate tetrahydrate 2.5101 g are dissolved in ultrapure water in a stoichiometric ratio of 1:100 g to 2:100 g to form a metal salt solution; wherein the molar concentration of the metal ions in the metal salt solution is 0.1 mol / L;

[0074] Step S2, adding sodium hydroxide and ammonia water to the metal salt solution, adjusting the pH value of the solution to 7.5-8.5, to obtain a mixed solution;

[0075] Step S3, continuously stirring and heating the mixed solution at 60° C. on a magnetic heating stirring table at a stirring speed of 80 r / min until a precipitate is generated; treating the mixed solution in a blast drying oven at 300° C. for 3 hours to obtain a nickel-cobalt-manganese precursor;

[0076] Step S4, heating the lithium hydroxide monohydrate and the nickel cobalt manganese precursor to 500°C in a muffle furnace at a heating rate of 2°C / min, treating for 3 hours, cooling to room temperature, and then heating to 850°C at a heating rate of 5°C / min and calcining for 10 hours to obtain a sintered product; grinding the sintered product in a mortar for 10 minutes until the D50 particle size is 5 μm to obtain a nickel cobalt manganese oxide lithium positive electrode material.

[0077] Comparative Example 2

[0078] The preparation of the nickel cobalt lithium manganese oxide positive electrode material of this comparative example comprises the following steps:

[0079] Step S1, according to LiNi 0.8 Co 0.1 Mn 0.1 The required lithium nitrate 6.895 g, nickel nitrate hexahydrate 23.2632 g, cobalt nitrate hexahydrate 2.9104 g, and manganese nitrate tetrahydrate 2.5101 g are dissolved in ultrapure water in a stoichiometric ratio of 1:100 g to 2:100 g to form a metal salt solution; wherein the molar concentration of the metal ions in the metal salt solution is 0.1 mol / L;

[0080] Step S2, adding glycine to the metal salt solution, and then adding a certain amount of ammonia water, adjusting the pH value of the solution to 8, to obtain a mixed solution; wherein the molar ratio of glycine to the metal ions in the metal salt solution is 1.5:1;

[0081] Step S3, continuously stirring and heating the mixed solution at 100° C. on a magnetic heating stirring table at a stirring speed of 80 r / min until black flocs are generated; treating the mixed solution in a blast drying oven at 280° C. for 3 hours to obtain a nickel cobalt manganese oxide lithium precursor;

[0082] Step S4, heating the lithium nickel cobalt manganese oxide precursor to 500°C in a muffle furnace at a heating rate of 2°C / min, treating for 3 hours, cooling to room temperature, and then heating to 850°C at a heating rate of 5°C / min and calcining for 10 hours to obtain a sintered product; grinding the sintered product in a mortar for 10 minutes until the D50 particle size is 5 μm to obtain a lithium nickel cobalt manganese oxide positive electrode material.

[0083] Comparative Example 3

[0084] The preparation of the nickel cobalt lithium manganese oxide positive electrode material of this comparative example comprises the following steps:

[0085] Step S1, according to LiNi 0.8 Co 0.1 Mn 0.1 The required lithium nitrate 6.895 g, nickel nitrate hexahydrate 23.2632 g, cobalt nitrate hexahydrate 2.9104 g, and manganese nitrate tetrahydrate 2.5101 g are dissolved in ultrapure water in a stoichiometric ratio of 1:100 g to 2:100 g to form a metal salt solution; wherein the molar concentration of the metal ions in the metal salt solution is 0.1 mol / L;

[0086] Step S2, adding urea to the metal salt solution, and then adding a certain amount of ammonia water, adjusting the pH value of the solution to 8, to obtain a mixed solution; wherein the molar ratio of urea to the metal ions in the metal salt solution is 1.2:1;

[0087] Step S3, continuously stirring and heating the mixed solution at 100° C. on a magnetic heating stirring table at a stirring speed of 80 r / min until black flocs are generated; treating the mixed solution in a blast drying oven at 280° C. for 3 hours to obtain a nickel cobalt manganese oxide lithium precursor;

[0088] Step S4, heating the lithium nickel cobalt manganese oxide precursor to 500°C in a muffle furnace at a heating rate of 2°C / min, treating for 3 hours, cooling to room temperature, and then heating to 850°C at a heating rate of 5°C / min and calcining for 10 hours to obtain a sintered product; grinding the sintered product in a mortar for 10 minutes until the D50 particle size is 5 μm to obtain a lithium nickel cobalt manganese oxide positive electrode material.

[0089] Test example

[0090] 1. Assembly of button battery

[0091] The nickel cobalt manganese oxide positive electrode material, carbon black and polytetrafluoroethylene of the embodiment and the comparative example are dispersed in N-methylpyrrolidone (NMP) solvent, and fully stirred and mixed to form a uniform positive electrode slurry; wherein the mass ratio of the nickel cobalt manganese oxide positive electrode material to the carbon black and polytetrafluoroethylene is 96:2:2;

[0092] The positive electrode slurry is evenly coated on the positive electrode current collector, rolled, and then punched into a small disc with a diameter of 12 mm using a mold. After drying and weighing, in a glove box under a nitrogen atmosphere, a 2025 button battery shell is used, a lithium metal disc is used as the negative electrode, and an electrolyte is injected to assemble a button battery. The electrolyte is a lithium hexafluorophosphate solution with a concentration of 2 mol / L, and the solvent is ethylene carbonate, diethyl carbonate, and propylene carbonate in a mass ratio of 2:5:3.

[0093] 2. Test the button cell as follows

[0094] 1. Gram capacity and first effect test

[0095] The button cell was tested for cycle performance at 25°C. The test process was as follows: the battery was charged to 4.5V at a constant current of 0.1C, then charged to 4.5V at a constant voltage of 0.05C, and then discharged to 3V at a discharge rate of 0.1C. The cycle was repeated three times. The charge and discharge capacity and the first efficiency of the first cycle were determined, and the gram capacity Q was calculated. 0.1C =Q 0.1C放 / m 正极活性物质的质量 and the first effect Q = Q 0.1C充 / Q 0.1C放 ×100%. Test results are shown in Table 1

[0096] Table 1

[0097] serial number D50 <![CDATA[Gram capacity Q 0.1C > First Effect Q Example 1 5μm 212mAh / g 90％ Example 2 5μm 200mAh / g 87％ Example 3 5μm 205mAh / g 84％ Example 4 5μm 208mAh / g 86％ Comparative Example 1 5μm 195mAh / g 85％ Comparative Example 2 5μm 191mAh / g 80％ Comparative Example 3 5μm 200mAh / g 83％

[0098] Figure 1 This is the element distribution diagram of the nickel cobalt manganese oxide positive electrode material in Example 1, and the element distribution diagram is obtained by transmission electron microscopy and EDS spectrum analysis. Figure 1 It can be seen that the elements are evenly distributed in the nickel cobalt manganese oxide positive electrode material prepared in Example 1. According to Table 1, the nickel cobalt manganese oxide positive electrode material prepared by the preparation method provided by the present invention has excellent capacity and initial efficiency.

[0099] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a nickel-cobalt-manganese-oxide lithium positive electrode material, characterized in that: The following steps are involved: Step S1, mixing lithium salt, nickel salt, cobalt salt, manganese salt and water to obtain a metal salt solution; Step S2, mixing the metal salt solution with a compound containing amino groups and carboxyl groups, adjusting the pH value to 7.2 to 8.5, to obtain a mixed solution; Step S3, heating and stirring the mixed solution and drying the mixed solution in sequence to obtain a lithium nickel cobalt manganese oxide precursor; Step S4, subjecting the lithium nickel cobalt manganese oxide precursor to a first sintering treatment and a second sintering treatment in sequence to obtain a lithium nickel cobalt manganese oxide positive electrode material.

2. The preparation method according to claim 1, characterized in that: The molar ratio of the metal ions in the metal salt solution to the compound containing amino groups and carboxyl groups is 1:(1.1-1.3).

3. The preparation method according to claim 1 or 2, characterized in that: The molar ratio of lithium, nickel, cobalt and manganese in the metal salt solution is (0.9-1.2): (0.5-0.9): (0.08-0.2): (0.08-0.2).

4. The preparation method according to claim 1 or 2, characterized in that: The temperature of the heating and stirring treatment is 80-120°C, the rotation speed is 60-100r / min, and the time is 6-8h; and / or, the temperature of the drying treatment is 250-300°C, and the time is 2-4h; and / or, the temperature of the first sintering treatment is 450-550°C, the time is 3-5h, and the heating rate is 1-3°C / min; and / or, the temperature of the second sintering treatment is 700-800°C, the time is 8-12h, and the heating rate is 2-4°C / min.

5. The preparation method according to claim 1 or 2, characterized in that: The sum of the molar concentrations of metal ions in the metal salt solution is 0.1-0.3 mol / L.

6. The preparation method according to claim 1 or 2, characterized in that: After the second sintering treatment, the second sintering product is further ground to obtain the nickel cobalt manganese oxide lithium positive electrode material.

7. The preparation method according to claim 1 or 2, characterized in that: The compound containing amino and carboxyl groups includes glycine; and / or the lithium salt includes at least one of lithium acetate and lithium nitrate; and / or the nickel salt includes at least one of nickel acetate, nickel nitrate and nickel sulfate; and / or the cobalt salt includes at least one of cobalt acetate, cobalt nitrate and cobalt sulfate; and / or the manganese salt includes at least one of manganese acetate, manganese nitrate and manganese sulfate.

8. A nickel-cobalt-manganese-oxide lithium positive electrode material, characterized in that: The method is prepared according to any one of claims 1 to 7.

9. The nickel-cobalt-manganese-oxide lithium positive electrode material according to claim 8, characterized in that: The chemical formula of the lithium nickel cobalt manganese oxide positive electrode material is Li a Ni b Co c Mn 1-b-c O2, among which, 0.9≤a≤1.2, 0.5≤b≤0.9, 0.08≤c≤0.

2.

10. A lithium ion battery, characterized in that: Including the nickel cobalt manganese oxide lithium positive electrode material as described in claim 8 or 9.

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