A nano-flaky spherical structure NC high-nickel precursor for NCA positive electrode material and preparation method thereof

Abstract

The present invention relates to the technical field of positive electrode materials, and in particular to a nano-sheet spherical structure NC high-nickel precursor for NCA positive electrode materials and a preparation method thereof. The present invention adopts a continuous flow extraction method to prepare a high-nickel precursor, and the method comprises: (1) preparing a binary metal mixed solution with nickel, cobalt inorganic salts and a first complexing agent, preparing a complexing agent solution with a second complexing agent and a dispersant, and preparing a soluble hydroxide into a precipitant solution; (2) adding water and inert gas into a reactor, introducing a complexing agent solution and a precipitant solution to maintain stirring and modulating a bottom liquid; (3) continuously introducing a metal mixed solution, a complexing agent solution and a precipitant solution into the reactor, and continuously increasing the flow rate of the metal mixed solution for co-deposition reaction; (4) the reacted material is post-treated to obtain a NC high-nickel precursor. The present invention adopts a one-step synthesis of a NC high-nickel precursor for NCA positive electrode materials, which has a nano-sheet structure, good sphericity, narrow particle size distribution, good consistency and high porosity.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ion battery positive electrode materials, and in particular to a nano-sheet spherical structure NC high-nickel precursor for NCA positive electrode material and a preparation method thereof. Background Art

[0002] Lithium-ion batteries are widely used in new energy vehicles, consumer electronics, energy storage and other fields due to their high energy density, long cycle life, safety and environmental protection. x Co y Al (1-x-y) O2 (referred to as NCA) and LiNi x Co y Mn (1-x-y) O2 (abbreviated as NCM) is collectively referred to as ternary positive electrode material, which is currently the most mainstream positive electrode material for lithium-ion batteries. The Mn element and the Al element both play a role in stabilizing the material structure and do not provide capacitance. Compared with NCM, where Mn exists in a +4 valence state, Al is in a +3 valence state in NCA, thus avoiding the reduction of the valence state of the Ni element. At the same time, the Al element has a stronger structural stabilizing effect, so NCA is more suitable for ultra-high nickel positive electrode material systems.

[0003] At present, the industrialized ternary cathode materials are all sintered by hydroxide precursors and lithium sources, so the performance of ternary cathode materials is more directly determined by the quality of ternary precursors. Co-deposition reaction is the most suitable process for industrial production of hydroxide precursors, but the solubility product of Al(OH)3 is much larger than the solubility product of Ni(OH)2 and Co(OH)2, which causes problems such as difficulty in sphering particles and uneven composition. Therefore, the use of NC precursors and aluminum sources to sinter to prepare NCA cathode materials has become one of the main industrial processes. Under this process, the prepared nickel-cobalt-aluminum material has inheritance of the structure and morphology of the precursor, and its primary particle morphology is blocky, strip-shaped, etc., but the primary particle structure of these morphologies is coarse, the porosity is low, and it is difficult to fully contact with the electrolyte, which affects the full play of its electrochemical morphology. Therefore, it is of great significance to synthesize a nano-sheet spherical structure NC high nickel precursor with good sphericity, narrow particle size distribution, good consistency, and high porosity for NCA cathode materials. Summary of the invention

[0004] The purpose of the present invention is to solve the problems of the prior art and provide a nano-flaky spherical structure NC high-nickel precursor for NCA positive electrode material and a preparation method thereof. The present invention aims to effectively control the ratio of the feed rate and the reaction slurry by controlling the continuous flow method, and at the same time regulate the reaction complex strength, pH, temperature and other conditions, synthesize a nano-flaky spherical structure NC high-nickel precursor for NCA positive electrode material, control the growth of grains along a certain crystal plane, effectively reduce the size of the primary particle layer, and increase the material porosity.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] One of the purposes of the present invention is to provide a method for preparing a nano-sheet spherical structure NC high-nickel precursor for NCA positive electrode material, comprising the following steps:

[0007] (1) preparing a binary mixed metal salt solution using a nickel inorganic salt, a cobalt inorganic salt and a first complexing agent; preparing a second complexing agent aqueous solution containing a dispersant; and preparing a hydroxide precipitant aqueous solution;

[0008] (2) adding pure water to the reaction kettle in advance, adding the second complexing agent aqueous solution and the hydroxide precipitant aqueous solution under the protection of inert gas, stirring the bottom liquid, and controlling the bottom liquid temperature, pH, second complexing agent concentration and stirring speed;

[0009] (3) continuously adding a binary mixed metal salt solution, a second complexing agent aqueous solution, and a hydroxide precipitant aqueous solution to the reactor, controlling the reaction temperature, pH, second complexing agent concentration, and stirring speed of the slurry to perform a co-precipitation reaction, continuously discharging the clear liquid in the reactor by solid-liquid separation, increasing the solid content in the reactor, controlling the slurry liquid level, and continuously increasing the flow rate of the binary mixed metal salt solution according to the reactor duration until the reaction particle size reaches the endpoint particle size;

[0010] (4) Post-treating the slurry from step (3) to obtain a NC high-nickel binary precursor.

[0011] Preferably, in step (1), the nickel inorganic salt, the cobalt inorganic salt and the first complexing agent can be simple substances (solid or liquid) or corresponding solutions, and more preferably the solution is an aqueous solution.

[0012] Preferably, in step (1), the nickel inorganic salt is one or more of nickel sulfate, nickel nitrate and nickel chloride, and the cobalt inorganic salt is one or more of cobalt sulfate, cobalt nitrate and cobalt chloride.

[0013] Preferably, in step (1), the first complexing agent is one or more of triethanolamine, ethylenediaminetetraacetic acid, sodium citrate, citric acid, and oxalic acid.

[0014] Preferably, the binary mixed metal salt solution in step (1) is an aqueous solution, that is, the solvent in the solution is water.

[0015] Preferably, the ratio of the nickel inorganic salt and the cobalt inorganic salt in the binary mixed metal salt solution in step (1) is such that the ratio of nickel to cobalt conforms to the formula Ni x Co 1-x The ratio of Ni to Co in (OH)2 is 0.6≤x<1, and more preferably 0.8≤x<1.

[0016] Preferably, the total metal concentration in the binary mixed metal salt solution in step (1) is 1.3-2.0 mol / L, and the concentration is the total concentration of the mixed metals, that is, the total concentration of nickel and cobalt metals.

[0017] Preferably, the concentration of the first complexing agent in the binary mixed metal salt solution in step (1) is 0.001 to 0.020 mol / L.

[0018] Preferably, the second complexing agent in step (1) is one or more of ammonia water and ammonium sulfate.

[0019] Preferably, the concentration of the second complexing agent in the second complexing agent aqueous solution in step (1) is 1 to 10 mol / L.

[0020] Preferably, the dispersant in step (1) is one or more of dodecyltrimethylammonium bromide, tetramethylammonium chloride, and dodecyltrimethylammonium bromide.

[0021] Preferably, in step (1), the concentration of the dispersant in the second complexing agent aqueous solution is 0.01 to 0.08 g / L.

[0022] Preferably, the hydroxide precipitant in step (1) is one or more of sodium hydroxide and potassium hydroxide.

[0023] Preferably, the concentration of the hydroxide precipitant aqueous solution in step (1) is 4 to 12 mol / L.

[0024] Preferably, the volume of the reactor in step (2) is 0.5 to 20 m 3 .

[0025] Preferably, the amount of pure water added in step (2) is 20% to 50% of the volume of the reactor.

[0026] Preferably, the inert gas in step (2) is a gas that does not react with the reactants and products, more preferably one or more of nitrogen, helium or argon.

[0027] Preferably, in step (2), the temperature, pH and concentration of the second complexing agent of the base solution are regulated to reach the target values ​​by controlling the amount of the complexing agent solution and the hydroxide precipitant aqueous solution added.

[0028] Preferably, the temperature of the base liquid in step (2) is 40-75°C.

[0029] Preferably, the pH of the base solution in step (2) is adjusted to 10.50-11.50.

[0030] Preferably, in step (2), the concentration of the second complexing agent in the base solution is 2.0-5.0 g / L.

[0031] Preferably, in step (2), the stirring speed is controlled to be 100 to 250 rpm.

[0032] Preferably, the initial flow rate of adding the binary mixed metal salt solution in step (3) is (reactor volume×1 / 100) L / h.

[0033] Preferably, in step (3), the flow rate of the binary mixed metal salt solution is controlled to increase to [initial flow rate × (1.03-1.08) x ]L / h, wherein x is the reaction time; more preferably, each unit time is per hour.

[0034] Preferably, in step (3), the reaction temperature is controlled at 40-75°C.

[0035] Preferably, in step (3), the flow rate of the precipitant added is controlled to control the pH of the slurry to be 10.50-11.50.

[0036] Preferably, in step (3), the flow rate of the aqueous solution of the second complexing agent is adjusted to control the concentration of the second complexing agent in the slurry to be 2.0 to 5.0 g / L.

[0037] Preferably, in step (3), the stirring speed is controlled to be 100 to 250 rpm.

[0038] Preferably, the reaction temperature, pH, second complexing agent concentration and stirring speed of the co-deposition reaction in step (3) are consistent with those in step (2).

[0039] Preferably, in step (3), the slurry level in the reactor is controlled to be maintained at 80-90% of the total volume of the reactor to further ensure the normal reaction and avoid losses caused by overflow or disruption of the reaction balance. More preferably, the slurry level in the reactor is controlled by a concentrator.

[0040] Preferably, in step (3), the particle size at the reaction endpoint is 8.0 to 15.0 μm.

[0041] Preferably, the post-treatment in step (4) includes conventional treatment steps such as solid-liquid separation, alkali washing, water washing, drying, screening, and iron removal.

[0042] More preferably, the solid-liquid separation step is a filtration step, and the solids reaching the end point particle size are separated by filtration.

[0043] More preferably, the alkaline solution in the alkaline washing is one or more of sodium hydroxide solution and sodium carbonate solution; more preferably, the concentration of the alkaline solution is 0.5-1.2 mol / L; more preferably, the temperature of the alkaline solution is 60-85° C. More preferably, the alkaline washing time is 10-30 min.

[0044] More preferably, the water temperature in the water washing is 60 to 85° C. More preferably, the water washing is performed until the sodium content is reduced to not more than 500 ppm.

[0045] More preferably, the drying temperature is 100-150°C.

[0046] More preferably, the mesh size of the sieving is 400 meshes, and large-sized foreign matter introduced or generated during the production process and a small amount of material agglomerates are filtered and removed by sieving.

[0047] Preferably, the NC high nickel binary precursor nanosheet size obtained in step (4) is 10-100 nm, the particle size is 8.0-15.0 μm, and the tap density is 1.5-2.3 g / cm 3 ; BET is 10~30m 2 / g.

[0048] Another object of the present invention is to provide a method for preparing the above-mentioned nano-flaky spherical structure NC high-nickel precursor for NCA positive electrode material, wherein the nano-flaky spherical structure NC high-nickel precursor for NCA positive electrode material is prepared, and the nano-flaky primary particle size is 10 to 100 nm, the particle size is 8.0 to 15.0 μm, and the tap density is 1.5 to 2.3 g / cm 3 ; BET is 10~30m 2 / g, good sphericity, narrow particle size distribution, good consistency and high porosity.

[0049] In the present invention, by adding a dispersant to the second complexing agent aqueous solution, the agglomeration of newly formed crystal nuclei in the initial stage of the reaction can be effectively inhibited, the sphericity of the particles can be ensured, and the consistency of the material can be increased. The dispersant and the second complexing agent solution are mixed and introduced to avoid excessive local concentration of the dispersant and metal mixed solution, thereby achieving the effect of reducing the particle size distribution of the material and enhancing the consistency.

[0050] In the present invention, the non-ammonia complexing agent (first complexing agent) is added to the binary mixed metal salt solution during the batching process, and a metal complex is formed before the solution is put into the reactor and contacts with the precipitant, thereby effectively reducing the generation rate of the coprecipitation product. After the binary mixed metal salt solution is added to the reactor, it acts together with the second complexing agent to further increase the Ni content in the solution. 2+ and Co 2+The saturation of the reactor is controlled to keep the nucleation rate and growth rate in the reactor at similar levels, so that the primary particles formed are flaky and uniform in size, and the secondary particles formed by accumulation have good sphericity. At the same time, the rate at which the binary mixed metal salt solution is added to the reactor is controlled. As the solid content of the particles in the reactor increases, the flow rate is continuously increased year-on-year, so that the number of primary particles formed increases proportionally with the total volume of secondary particles, effectively increasing the consistency of the particles.

[0051] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention provides a nano-sheet spherical structure NC high-nickel precursor for NCA positive electrode material and a preparation method thereof, wherein the method controls the reaction nucleation rate and growth rate through the synergistic effect of a double complexing agent to form nano-sheet primary particles, and simultaneously continuously increases the flow to control the uniform accumulation of the primary particles to form an NC high-nickel precursor with good sphericity, narrow particle size distribution, good consistency, and high porosity. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 , Figure 2 , Figure 3 This is a scanning electron microscope image of the nano-sheet-shaped spherical structure NC high-nickel precursor for NCA positive electrode material prepared in Example 1;

[0053] Figure 4 , Figure 5 , Figure 6 This is a scanning electron microscope image of the nano-sheet-shaped spherical structure NC high-nickel precursor for NCA positive electrode material prepared in Example 2;

[0054] Figure 7 , Figure 8 , Fig. 9 This is a scanning electron microscope image of the high-nickel precursor prepared in Comparative Example 1. DETAILED DESCRIPTION

[0055] The technical solution of the present invention is further described in detail below through specific embodiments and in combination with the accompanying drawings. Obviously, the following embodiments are only some embodiments of the present invention, not all embodiments. It should be pointed out that all embodiments made by those skilled in the art without departing from the main concept of the present invention and making non-essential changes are still within the protection scope of the present invention.

[0056] The present invention provides a nano-sheet spherical structure NC high-nickel precursor for NCA positive electrode material and a preparation method thereof, wherein the preparation method comprises the following steps:

[0057] Nickel inorganic salt and cobalt inorganic salt are used, and the feeding ratio is based on the molar ratio of nickel to cobalt: Ni x Co y(OH)2, (x+y=1, x≥0.6), and adding a first complexing agent, which is one or more of ethylenediaminetetraacetic acid, triethanolamine, sodium citrate, citric acid, and oxalic acid, to prepare a binary mixed metal salt solution with a total metal salt concentration (total nickel and cobalt concentration) of 1.3-2.0 mol / L and a first complexing agent concentration of 0.001-0.020 mol / L, and the solvent is water;

[0058] A 1-10 mol / L ammonia water or ammonium sulfate solution containing 0.01-0.08 g / L of a dispersant is prepared, and the solvent is water, as a second complexing agent aqueous solution (also referred to as a second complexing agent solution in the present invention); the dispersant can be one or more of dodecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, and tetramethylammonium chloride;

[0059] A hydroxide precipitant aqueous solution (also referred to as a precipitant aqueous solution in the present invention) having a concentration of 4 to 12 mol / L is prepared, wherein the hydroxide precipitant is one or more of sodium hydroxide and potassium hydroxide;

[0060] In the volume of 0.5~20m 3 Add 20% to 50% of the volume of the reactor into the reactor in advance, pump in the second complexing agent solution and the precipitant aqueous solution under the protection of an inert atmosphere such as nitrogen, argon, etc., keep stirring to adjust the bottom liquid, control the bottom liquid temperature to 40 to 75°C, the pH to 10.50 to 11.50, the second complexing agent concentration to 2.0 to 5.0 g / L, and the stirring speed to 100 to 250 rpm.

[0061] The binary mixed metal salt solution, the second complexing agent solution and the precipitant aqueous solution are continuously pumped into the reactor, the reaction temperature is controlled to be 40-75°C, the pH is 10.50-11.50, the concentration of the second complexing agent is 2.0-5.0 g / L, and the stirring speed is 105-250 rpm for co-precipitation reaction. The initial flow rate of the binary mixed metal salt solution is (reactor volume × 1 / 100) L / h. The PLC system controls the binary mixed metal salt solution pumping flow rate to increase to [initial flow rate × (1.03-1.08)] per hour. x ]L / h, where x is the reaction time. The clear liquid in the reactor is continuously discharged through the concentrator solid-liquid separation to increase the solid content in the reactor, and the slurry liquid level (slurry volume) in the reactor is controlled to be maintained at 80-90% of the total volume of the reactor until the reaction particle size reaches the end point particle size of 8.0-15.0μm, and the reaction is stopped;

[0062] After filtering the slurry after the reaction, the solid is washed with a sodium hydroxide alkaline solution or a sodium carbonate alkaline solution with a concentration of 0.5-1.2 mol / L and a temperature of 60-85°C for 10-30 minutes, washed with hot pure water at a temperature of 60-85°C, dried at a temperature of 100-150°C, sieved, and iron removed to obtain a NC high-nickel binary precursor. The obtained NCA positive electrode material has a nano-sheet spherical structure NC high-nickel precursor, whose nano-sheet size is 10-100nm, the particle size is 8.0-15.0μm, and the tap density is 1.5-2.3g / cm 3 ; BET is 10~30m 2 / g, good sphericity, narrow particle size distribution, good consistency and high porosity.

[0063] The technical solutions described in the present invention can all be implemented and have corresponding effects. The technical solutions and effects of the present invention are further illustrated by specific embodiments below. However, it should be noted that the following embodiments are only used to further illustrate the technical solutions of the present invention, but are not used to constitute any limitation on the technical solutions of the present invention.

[0064] Example 1

[0065] Nickel sulfate and cobalt sulfate inorganic salts are used according to the molar ratio of nickel to cobalt inorganic salts: Ni 0.95 Co 0.05 (OH)2 is added as a feed, and ethylenediaminetetraacetic acid is added to prepare a binary metal mixed solution with a total metal salt concentration of 1.5 mol / L and an ethylenediaminetetraacetic acid concentration of 0.003 mol / L; an ammonia solution with an ammonia concentration of 8 mol / L and containing 0.05 g / L of dodecyltrimethylammonium bromide dispersant is prepared as a complexing agent solution; and sodium hydroxide with a concentration of 5 mol / L is prepared as a precipitant aqueous solution.

[0066] In a volume of 1m 3 Add 30% pure water of the reactor volume into the reactor in advance, pump in the complexing agent solution and the precipitant solution under nitrogen protection to keep stirring to prepare the bottom liquid, control the bottom liquid temperature to 65°C, pH to 11.10, ammonia concentration to 3.0g / L, and stirring speed to 250rpm.

[0067] The metal mixed solution, complexing agent solution and precipitant solution were continuously pumped into the reactor, the reaction temperature was controlled to be 65°C, the pH was 11.10, the ammonia concentration was 3.0 g / L, and the stirring speed was 250 rpm for co-precipitation reaction. The initial flow rate of the metal mixed solution was 10 L / h. The PLC system controlled the metal mixed solution pumping flow rate to increase by [10×1.04 x]L / h, where x is the reaction time. The clear liquid in the reactor is continuously discharged through the concentrator for solid-liquid separation to increase the solid content in the reactor. The reactor liquid level is controlled to maintain the total reactor liquid level at 80-90% until the reaction particle size reaches 10.0μm, and the reaction is stopped.

[0068] The slurry after the reaction was washed with a sodium hydroxide alkaline solution with a concentration of 0.8 mol / L and a temperature of 75°C for 20 minutes, washed with hot pure water at a temperature of 75°C, dried at a temperature of 110°C, sieved through 400 mesh, and iron removed to obtain an NC high-nickel binary precursor with a yield of not less than 98.5%.

[0069] The high nickel ternary precursor material prepared in Example 1 of the present invention was tested by scanning electron microscopy. The test results are as follows: Figure 1 , Figure 2 , Figure 3 As shown, it can be seen that the high nickel ternary precursor material prepared in Example 1 of the present invention has good sphericity, high particle consistency, a primary particle size of nanometer level, and a significant nano-flaky spherical structure.

[0070] The high-nickel NC high-nickel binary precursor prepared in Example 1 of the present invention has a D50 of 8.85 μm and a tap density of 1.86 g / cm 3 , BET is 11.33m 2 / g, the particle size distribution ((D90-D10) / D50) is 0.39, the particle size distribution is narrow, and it has a significant nano-sheet structure with a size of 26nm.

[0071] Example 2

[0072] Nickel sulfate and cobalt sulfate inorganic salts are used according to the molar ratio of nickel to cobalt inorganic salts: Ni 0.88 Co 0.12 (OH)2, and add oxalic acid to prepare a binary metal mixed solution with a total metal salt concentration of 1.6 mol / L and an oxalic acid concentration of 0.02 mol / L; prepare an ammonia solution with an ammonia concentration of 8 mol / L and containing 0.08 g / L of tetramethylammonium chloride dispersant as a complexing agent solution; prepare sodium hydroxide with a concentration of 10 mol / L as a precipitant aqueous solution.

[0073] In a volume of 8m 3 Add 30% pure water of the reactor volume into the reactor in advance, pump in the complexing agent solution and the precipitant solution under nitrogen protection and keep stirring to prepare the bottom liquid, control the bottom liquid temperature to 60°C, pH to 10.70, ammonia concentration to 4.5g / L, and stirring speed to 180rpm.

[0074] The metal mixed solution, complexing agent solution and precipitant solution were continuously pumped into the reactor, the reaction temperature was controlled at 60°C, pH was 10.70, ammonia concentration was 4.5 g / L, and the stirring speed was 180 rpm for co-precipitation reaction. The initial flow rate of the metal mixed solution was 80 L / h. The PLC system controlled the metal mixed solution pumping flow rate to increase by [80 × 1.03 x ]L / h, where x is the reaction time. The clear liquid in the reactor is continuously discharged through the concentrator for solid-liquid separation to increase the solid content in the reactor. The reactor liquid level is controlled to maintain the total reactor liquid level at 80-90% until the reaction particle size reaches 14.0μm, and the reaction is stopped.

[0075] The slurry after the reaction was washed with a sodium carbonate alkaline solution with a concentration of 0.5 mol / L and a temperature of 75°C for 10 minutes, washed with hot pure water at a temperature of 75°C, dried at a temperature of 120°C, sieved, and iron removed to obtain an NC high-nickel binary precursor.

[0076] The high nickel ternary precursor material prepared in Example 2 of the present invention was subjected to scanning electron microscopy testing, and the test results are as follows: Figure 4 , Figure 5 , Figure 6 As shown, it can be seen that the high nickel ternary precursor material prepared in Example 2 of the present invention has good sphericity, high particle consistency, and a primary particle size of nanometer level.

[0077] The high-nickel NC high-nickel binary precursor prepared in Example 2 of the present invention has a D50 of 13.89 μm, a tap density of 1.96 g / cm3, a BET of 14.33 m2 / g, and has a significant nano-sheet structure with a size of 22 nm.

[0078] Comparative Example 1

[0079] Nickel sulfate and cobalt sulfate inorganic salts are used according to the molar ratio of nickel to cobalt inorganic salts: Ni 0.90 Co 0.10 (OH)2 is added to prepare the total concentration of metal salt to be 1.6 mol / L; an ammonia solution with an ammonia concentration of 8 mol / L is prepared as a complexing agent solution; and sodium hydroxide with a concentration of 10 mol / L is prepared as a precipitant aqueous solution.

[0080] In a volume of 8m 3 Add 30% pure water of the reactor volume into the reactor in advance, pump in the complexing agent solution and the precipitant solution under nitrogen protection to keep stirring to prepare the bottom liquid, control the bottom liquid temperature to 60°C, pH to 11.00, ammonia concentration to 4.0g / L, and stirring speed to 180rpm.

[0081] The metal mixed solution, complexing agent solution and precipitant solution were continuously pumped into the reactor, the reaction temperature was controlled to be 60°C, pH to be 11.00, ammonia concentration to be 4.0g / L, and the stirring speed to be 180rpm for co-precipitation reaction. The initial flow rate of the metal mixed solution was 150L / h, and the flow rate was increased to 450L / h after the particle size reached 6 microns. The clear liquid in the reactor was continuously discharged through the concentrator solid-liquid separation to increase the solid content in the reactor, and the liquid level of the reactor was controlled to maintain the total liquid level of the reactor at 80-90%, until the reaction particle size reached 14.0μm, and the reaction was stopped.

[0082] The slurry after the reaction was washed with a sodium hydroxide alkaline solution with a concentration of 0.8 mol / L and a temperature of 75°C for 20 minutes, washed with hot pure water at a temperature of 75°C, dried at a temperature of 110°C, sieved, and iron removed to obtain an NC high-nickel binary precursor.

[0083] The high-nickel NC high-nickel binary precursor prepared in Comparative Example 1 of the present invention has a D50 of 14.31 μm, a tap density of 2.10 g / cm3, a BET of 3.45 m2 / g, and a primary particle size of 276 nm.

[0084] The high nickel precursor material prepared in comparative example 1 of the present invention was subjected to scanning electron microscopy test, and the electron microscope results are as follows: Figure 7 , Figure 8 , Fig. 9 As shown, combined with the specific data, it can be seen that the high nickel ternary precursor material prepared in Comparative Example 1 of the present invention has poor sphericity, significantly lower particle consistency, and large primary particle size. Compared with the embodiment of the present invention, it can be seen that the method provided by the present invention can significantly improve the sphericity, consistency and primary particle size of the prepared precursor, thereby having broad application prospects and research significance.

[0085] The above-described embodiments are only preferred solutions of the present invention and are not intended to limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

Claims

1. A method for preparing a nano-sheet spherical structure NC high-nickel precursor for NCA positive electrode material, characterized in that: The steps include: (1) preparing a binary mixed metal salt solution using a nickel inorganic salt, a cobalt inorganic salt and a first complexing agent; preparing a second complexing agent aqueous solution containing a dispersant; and preparing a hydroxide precipitant aqueous solution; (2) Under the protection of inert gas, adding a second complexing agent aqueous solution and a hydroxide precipitant aqueous solution into a reaction kettle containing water to prepare a base solution; (3) continuously adding a binary mixed metal salt solution, a second complexing agent aqueous solution and a hydroxide precipitant aqueous solution to the reactor in step (2) to carry out a co-precipitation reaction, and continuously increasing the flow rate of the added binary mixed metal salt solution according to the reaction time until the end particle size is reached; (4) post-treating the slurry in step (3) to obtain a NC high-nickel binary precursor; The first complexing agent is one or more selected from triethanolamine, ethylenediaminetetraacetic acid, sodium citrate and citric acid, and the concentration of the first complexing agent in the binary mixed metal salt solution is 0.001-0.020 mol / L; the second complexing agent is one or more selected from ammonia water and ammonium sulfate, and the concentration of the second complexing agent is 1-10 mol / L; the initial flow rate of adding the binary mixed metal salt solution in step (3) is (volume of the reactor × 1 / 100) L / h; the flow rate of adding the binary mixed metal salt solution is increased to [initial flow rate × (1.03-1.08) x] L / h per unit time, wherein x is the reaction time.

2. The method for preparing a nano-sheet spherical structure NC high-nickel precursor for NCA positive electrode material according to claim 1, characterized in that: In the step (1), the ratio of the nickel inorganic salt and the cobalt inorganic salt in the binary mixed metal salt solution is such that the ratio of nickel to cobalt conforms to the formula Ni x Co 1-x The ratio of Ni to Co in (OH)2 is calculated, where 0.6≤x<1; the total metal concentration in the binary mixed metal salt solution is 1.3~2.0mol / L.

3. The method for preparing a nano-sheet spherical structure NC high-nickel precursor for NCA positive electrode material according to claim 1, characterized in that: The dispersant in step (1) is one or more of dodecyltrimethylammonium bromide, tetramethylammonium chloride, and dodecyltrimethylammonium bromide, and the concentration of the dispersant in the second complexing agent aqueous solution is 0.01-0.08 g / L.

4. The method for preparing a nano-sheet spherical structure NC high-nickel precursor for NCA positive electrode material according to claim 1, characterized in that: The hydroxide precipitant in step (1) is one or more of sodium hydroxide and potassium hydroxide, with a concentration of 4-12 mol / L.

5. The method for preparing a nano-sheet spherical structure NC high-nickel precursor for NCA positive electrode material according to claim 1, characterized in that: In step (2), the amount of water in the reactor is 20% to 50% of the volume of the reactor.

6. The method for preparing a nano-sheet spherical structure NC high-nickel precursor for NCA positive electrode material according to claim 1, characterized in that: In step (2), the temperature of the base liquid is 40-75° C., the pH is 10.50-11.50, the concentration of the second complexing agent in the base liquid is 2.0-5.0 g / L, and the stirring speed is 100-250 rpm.

7. The method for preparing a nano-sheet spherical structure NC high-nickel precursor for NCA positive electrode material according to claim 1, characterized in that: The particle size at the reaction end point in step (3) is 8.0-15.0 μm.

8. A nano-sheet spherical structure NC high-nickel precursor for NCA positive electrode material prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The NC high nickel binary precursor nanosheet size is 10~100nm, the particle size is 8.0~15.0μm, and the tap density is 1.5~2.3g / cm 3 ; BET is 10~30m 2 / g.

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