Inside-tight and outside-loose type high-nickel ternary precursor and preparation method thereof

Abstract

The invention belongs to the technical field of lithium ion battery positive electrode materials, and relates to an inner-tight outer-loose type high-nickel ternary precursor and a preparation method thereof. The method comprises the following steps: 1) introducing a nickel-cobalt-manganese ternary mixed solution, a complexing agent and a precipitator into a first reaction kettle for co-deposition to prepare a nickel-cobalt-manganese compact core structure; 2) washing the inner core, quantitatively putting the inner core into a second reaction kettle again, and introducing a nickel-cobalt-manganese ternary mixed solution, a complexing agent, a precipitator and an inorganic alkali aluminum solution to prepare an aluminum-containing nickel-cobalt-manganese outer core structure; and 3) after the overall particle size reaches the target particle size, putting the reacted material into a strong alkali solution, and stirring to dissolve out aluminum hydroxide in the outer core to form a loose structure, thereby obtaining the tight-inside loose-outside high-nickel ternary precursor. The precursor prepared by the invention has good microstructure stability and rate capability, can realize industrialization without additional equipment on the basis of existing industrial equipment, and has wide industrial application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ion battery positive electrode materials, and in particular to a dissolution method for preparing an inner-tight and outer-loose high-nickel ternary precursor and a preparation method thereof. Background Art

[0002] In the field of lithium-ion battery cathode materials, the theoretical energy density of high-nickel NCM-type ternary cathode materials can reach 600Whk / g. However, as the proportion of nickel in ternary cathode materials increases, although the energy density of the materials can be improved, the reduction of cobalt content will lead to a decrease in the material rate performance, and the reduction of manganese content will lead to a decrease in the stability of the material structure and a faster decay of the cycle life. Therefore, other methods must be used to compensate for the inherent disadvantages of high-nickel ternary cathode materials in material design.

[0003] Currently, the industrialized ternary positive electrode materials are all prepared by solid-phase sintering of a ternary precursor and a lithium salt mixture. The particle size, internal pore structure, etc. of the ternary positive electrode materials have good inheritance of the ternary precursor. Therefore, the structural design of the ternary precursor plays a decisive role in the electrochemical performance of the ternary positive electrode material.

[0004] It is of great significance to design a high-nickel ternary precursor that can make high-nickel ternary cathode materials have excellent rate performance and cycle stability while giving full play to their own advantages of high specific capacity. In the field of low-nickel ternary precursors, the interior of the ternary precursor particles is generally a dense structure with few pores. The cathode materials prepared by the ternary precursor particles have a single lithium ion diffusion path, large diffusion resistance, and insufficient rate performance. In addition, the battery has always had the problem of unstable particle structure strength with repeated charging and discharging, which will easily cause cracking in the particle unit, resulting in a shorter life of lithium secondary batteries, lower capacity, and poor safety performance during use. With the increase of nickel content, the high-nickel ternary precursor gradually changes from a continuous process to an intermittent concentration process to improve the consistency between particles. However, with the increase of nickel content, the stress accumulation caused by the increase of reaction solid content, and the increase of particle size, the high-nickel precursor particles have a greater risk of cracking, and the reduction of cobalt content makes the rate performance insufficient. If a compact structure is formed in the center of the ternary cathode material and a loose, porous and well-radial structure is formed on the outside, the volume change of the material and the structural damage caused by side reactions can be effectively alleviated. The loose, porous and radial structure can form more lithium ion migration channels, accelerate the ion migration rate and effectively reduce the electrochemical polarization, so that the material has better rate performance. Therefore, it is very necessary to prepare a high-nickel ternary precursor with a tight inside and loose outside. Summary of the invention

[0005] The present invention aims to overcome the deficiencies of the prior art and provide a high-nickel ternary precursor with a tight inner and loose outer structure and a preparation method thereof. In the preparation process of the high-nickel ternary precursor, during the reaction growth of the inner core of the particles, the process is adjusted so that the primary particles are closely stacked to form a dense inner core structure to strengthen the mechanical structural strength of the material; during the reaction growth of the outer core of the particles, an inorganic aluminum alkali solution is introduced in addition to the nickel, cobalt and manganese raw materials to inhibit the growth of the primary particles, thereby obtaining a smaller size of the primary particles; the reacted material is immersed in a strong alkali solution to dissolve the generated aluminum hydroxide, so that the outer core has a porous and loose structure, thereby obtaining a high-nickel ternary precursor with a tight inner and loose outer structure, which improves the rate performance of the material while strengthening the microstructural stability of the material. The first purpose of the present invention is to provide a high-nickel ternary precursor with a tight inner and loose outer structure. The second purpose of the present invention is to provide a method for preparing a high-nickel ternary precursor with a tight inner and loose outer structure.

[0006] The technical solution adopted by the present invention to solve the above problems is:

[0007] The present invention provides a method for preparing an inner-tight and outer-loose high-nickel ternary precursor, comprising the following steps:

[0008] (1) preparing a ternary mixed metal salt solution using nickel, cobalt and manganese inorganic salts; preparing an inorganic aluminum base solution; preparing a precipitant aqueous solution; and preparing a complexing agent aqueous solution;

[0009] (2) filling the first reaction kettle and the first concentrator with pure water and circulating the water, introducing a protective gas, introducing a complexing agent aqueous solution and a precipitant aqueous solution to adjust the complexing agent concentration and the first pH, and controlling the reaction temperature;

[0010] At a first stirring speed, the ternary mixed metal salt solution, the complexing agent aqueous solution and the precipitant aqueous solution are simultaneously introduced into the reaction kettle, and the reaction pH is controlled to maintain a first pH;

[0011] When the particle size of the reactants reaches the target particle size of the kernel, the introduction of the ternary mixed metal salt solution, the complexing agent aqueous solution and the precipitant aqueous solution is stopped, and the kernel slurry after the reaction is pumped into a centrifuge for washing and drying to obtain a kernel filter cake for use;

[0012] (3) Filling the second reactor and the second concentrator with pure water and circulating it, introducing protective gas, introducing a complexing agent aqueous solution and a precipitant aqueous solution to adjust the complexing agent concentration and the second pH, controlling the reaction temperature, and adding a certain amount of kernel filter cake;

[0013] Under the condition of the second stirring speed, the ternary mixed metal salt solution, the complexing agent aqueous solution, the precipitant aqueous solution and the inorganic aluminum base solution are simultaneously introduced into the reaction kettle, the reaction pH is controlled to maintain the second pH, and the reaction stirring is stepped down from the second stirring speed to the third stirring speed;

[0014] The reaction is stopped when the particle size of the reactants reaches the overall target particle size;

[0015] (4) The reacted material is transferred to an aging kettle and allowed to stand, the supernatant is removed, and a strong alkaline solution is added and stirred to dissolve the aluminum hydroxide in the outer core to form a porous and sparse structure; after post-treatment, a high-nickel ternary precursor with a tight inside and a loose outside is obtained.

[0016] Preferably, the nickel, cobalt and manganese inorganic salts in step (1) are one or more of the corresponding sulfates, nitrates and chlorides; more preferably, the nickel inorganic salt is one or more of nickel sulfate, nickel nitrate and nickel chloride, the cobalt inorganic salt is one or more of cobalt sulfate, cobalt nitrate and cobalt chloride, and the manganese inorganic salt is one or more of manganese sulfate, manganese nitrate and manganese chloride.

[0017] Preferably, the total concentration of metals (nickel, cobalt, and manganese) in the ternary mixed metal salt solution in step (1) is 1.0 to 2.3 mol / L.

[0018] Preferably, the ratio of nickel, cobalt and manganese in the ternary mixed metal salt solution in step (1) conforms to the formula Ni x Co y Mn (1-x-y) (OH)2, where 0 <x<0.98,0<y<0.40。

[0019] Preferably, the inorganic aluminum in the inorganic aluminum alkali solution in step (1) is one or more of sodium aluminate and aluminum sulfate; more preferably, the aluminum concentration in the inorganic aluminum alkali solution in step (1) is 0.10-1.0 mol / L, the alkali is one or more of sodium hydroxide and potassium hydroxide, and the pH value of the inorganic aluminum alkali solution is adjusted to 13.00-13.50.

[0020] Preferably, the precipitant in step (1) is one or more of sodium hydroxide and potassium hydroxide. More preferably, the concentration of the precipitant aqueous solution in step (1) is 5.0 to 12.0 mol / L.

[0021] Preferably, the complexing agent in step (1) is one or more of ammonia water, ammonium sulfate, sodium ascorbate, salicylic acid, and oxalic acid. More preferably, the concentration of the complexing agent aqueous solution in step (1) is 1.0 to 11.0 g / L.

[0022] Preferably, the volume of the first reactor in step (2) is 1 to 10 m 3 More preferably, the volume of the first concentrator in step (2) is 0.1 to 3 m 3 .

[0023] Preferably, the protective gas in step (2) is one or more of nitrogen or helium.

[0024] Preferably, in step (2), the reaction temperature is 45-70°C; the concentration of the reaction complexing agent is 0.5-10.0 g / L; the first pH of the reaction is 10.30-11.00; the first stirring speed is 200-540 rpm; the pumping flow rate of the ternary mixed metal salt solution is 30-600 L / h; and the target particle size of the kernel is 3.0-7.0 μm.

[0025] Preferably, in step (2), the centrifuge water washing time is 200 to 800 seconds; and the centrifuge water washing temperature is 60 to 75°C.

[0026] Preferably, the moisture content of the inner core filter cake in step (2) is 10-25%.

[0027] Preferably, the volume of the second reactor in step (3) is 1 to 10 m 3 More preferably, the volume of the second concentrator in step (3) is 0.1 to 3 m 3 .

[0028] Preferably, the protective gas in step (3) is one or more of nitrogen or helium.

[0029] Preferably, in step (3), the reaction temperature is 45-70°C; the concentration of the reaction complexing agent is 0.5-10.0 g / L; the second pH of the reaction is 10.00-11.20; the second stirring speed is 150-300 rpm; the pumping flow rate of the ternary mixed metal salt solution is 30-600 L / h; the pumping flow rate of the inorganic aluminum alkali solution is 2-100 L / h; the third stirring speed is 30-100 rpm; and the overall target particle size is 8-18 μm.

[0030] Preferably, the weight of the kernel filter cake added in step (3) is [(aV / D 3 *d 3 ) / (1-s)]kg;

[0031] Where a is a constant, ranging from 200 to 800;

[0032] V is the volume of the second reactor, in m 3 ;

[0033] D is the overall target particle size, in μm;

[0034] d is the target particle size of the core, in μm;

[0035] s is the moisture content of the filter cake, in %.

[0036] Preferably, the stirring speed in step (3) is stepped down by 20 rpm per hour. A high speed design in the early stage of the reaction can prevent the adhesion between particles to produce twin particles. As the particle size increases and the solid content of the reaction system increases, the risk of adhesion will decrease but the risk of ball cracking will increase. Reducing the speed can reduce the increase in internal stress of the particles leading to ball cracking.

[0037] Preferably, in step (3), the second stirring speed is not greater than the first stirring speed, and the second pH is not greater than the first pH.

[0038] Preferably, the standing time in step (4) is 2 to 4 hours.

[0039] Preferably, the strong base added in step (4) is at least one of sodium hydroxide and potassium hydroxide; more preferably, the mass concentration of the strong base solution is 32%, and the added volume is 0.5 to 5 m 3 More preferably, the stirring time in step (4) is 10 to 24 hours.

[0040] Preferably, the post-treatment includes washing, centrifuging, drying, batch mixing, screening, and iron removal of the dissolved material to obtain an inner-tight and outer-loose high-nickel precursor;

[0041] More preferably, the water washing temperature is 60 to 75°C;

[0042] More preferably, the drying temperature is 100-150°C.

[0043] Preferably, the compacted structure size of the ternary precursor obtained by the preparation method is 3-7 μm; more preferably, the overall particle size of the ternary precursor is 8.0-18.0 μm, and the particle size distribution is 0.2-0.45; more preferably, the tap density of the ternary precursor is 1.8-2.3 g / cm 3 More preferably, the BET of the ternary precursor is 8 to 20 m 2 / g.

[0044] The present invention also provides a ternary precursor with tight inner and loose outer parts prepared by any of the above preparation methods, wherein the internal compact structure size of the precursor is 3-7 μm, the particle size is 8.0-18.0 μm, the particle size distribution is 0.2-0.45, and the tap density is 1.8-2.3 g / cm 3 , BET is 8~20m 2 / g.

[0045] The present invention adopts a process design to pass a ternary mixed solution of nickel, cobalt and manganese, a complexing agent and a precipitant into a reactor for co-deposition to prepare a nickel, cobalt and manganese inner core structure with close packing between primary particles. After the inner core particle size reaches a target particle size, the reaction is stopped and the inner core particles are washed and separated. The inner core particles are then used as seed crystals to continue the reaction, and a ternary mixed solution of nickel, cobalt and manganese, an inorganic aluminum alkali solution, a complexing agent and a precipitant are passed into a reactor for co-deposition to prepare an aluminum-containing nickel, cobalt and manganese outer core structure. The addition of aluminum inhibits the growth of primary particles, thereby obtaining a smaller-sized primary particle morphology. After the overall particle size reaches the target particle size, the reacted material is placed in a strong alkaline solution and stirred to dissolve the aluminum hydroxide in the inner core to form a porous and loose outer core structure, thereby obtaining a high-nickel ternary precursor with tight inside and loose outside, which improves the rate performance of the material while strengthening the microstructural stability of the material.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] In the technical solution described in the present invention, the characteristics of aluminum amphoteric metals are utilized, aluminate or aluminum ions are used as aluminum sources, and nickel-cobalt-manganese-aluminum hydroxide outer cores are prepared by co-precipitation reaction with nickel-cobalt-manganese metal ions under weak alkaline conditions, and aluminum hydroxide is evenly distributed in the outer core, while the growth of primary particles is inhibited, thereby obtaining a smaller primary particle morphology. After the co-precipitation is completed, the prepared particles are stirred in a strong alkaline environment to dissolve the aluminum hydroxide in the outer core and form a porous and loose outer core structure;

[0048] In the technical scheme described in the present invention, the inner core size can be accurately controlled by reaction time, the inner core material can be weighed again after washing to accurately control the number of seed crystals, and the growth rate of the outer core can be effectively controlled. During the outer core growth process, the growth ratio of outer core aluminum hydroxide can be accurately controlled by controlling the pumping rate of alkali aluminum solution, thereby achieving the control of the outer core porosity.

[0049] Compared with the existing ternary precursor preparation technology, the technology described in the present invention can achieve quantitative control of the inner and outer core sizes and porosity, and can be industrialized without adding additional equipment on the basis of existing industrial equipment, and has broad industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1-1 , Figure 1-2 This is a scanning electron microscope image of the inner-tight and outer-loose high-nickel ternary precursor prepared by the dissolution method in Example 1;

[0051] Figure 2-1 , Figure 2-2 This is a scanning electron microscope image of the inner-tight and outer-loose high-nickel ternary precursor prepared by the dissolution method in Example 2;

[0052] Figure 3-1 , Figure 3-2SEM image of the inner-dense and outer-loose type high-nickel ternary precursor prepared by the dissolution method in Example 3;

[0053] Figure 4-1 、 Figure 4-2 SEM image of the high-nickel ternary precursor prepared in Comparative Example 1.

[0054] Figure 5-1 、 Figure 5-2 SEM image of the high-nickel ternary precursor prepared in Comparative Example 2. Detailed implementation manners

[0055] The technical solutions of the present invention will be further specifically described below through specific examples in combination with the accompanying drawings. Obviously, the following examples are only partial examples of the present invention, not all examples. It should be noted that all examples made by those skilled in the art without departing from the main concept of the present invention and making non-essential changes still fall within the protection scope of the present invention.

[0056] In the examples of the present invention, the experimental methods and conditions used are all conventional methods and conventional conditions unless otherwise specified. The materials, reagents or instruments used in the examples can be obtained from commercial channels or prepared by conventional methods unless otherwise specified. The reaction conditions reflected in the content of the present invention can all achieve the reactions and obtain the products with expected effects. Due to space limitations, some examples are listed below to further illustrate the advantages of the technical solutions of the present invention.

[0057] The present invention provides an inner-dense and outer-loose type high-nickel ternary precursor prepared by a dissolution method and a preparation method thereof. The steps of the preparation method are as follows:

[0058] Prepare a ternary mixed metal salt solution with a molar ratio of Ni x Co y Mn (1-x-y) (OH)2, 0 < x < 0.98, 0 < y < 0.40, and the total concentration of metals (nickel, cobalt, and manganese) is 1.0 - 2.3 mol / L; prepare an inorganic aluminum alkali solution with an aluminum concentration of 0.10 - 1.0 mol / L by using an inorganic aluminum salt and adjusting the pH value of the solution to 13.00 - 13.50 with sodium hydroxide; prepare an aqueous solution of a precipitating agent with a concentration of 5.0 - 12.0 mol / L; prepare an aqueous solution of a complexing agent with a concentration of 1.0 - 11.0 g / L;

[0059] In a first reaction kettle with a volume of 1 - 10 m 3 and a second reaction kettle with a volume of 0.1 - 3 m 3The concentrator is filled with pure water and circulated, and protective gas is introduced. The complexing agent aqueous solution and the precipitant aqueous solution are introduced to adjust the complexing agent concentration to 0.5-10.0 g / L and the first pH to 10.30-11.00, and the reaction temperature is controlled to 45-70°C. Under the condition that the first stirring speed is 200-540rpm, the ternary mixed metal salt solution is pumped into the reactor at a flow rate of 30-600L / h, and the complexing agent aqueous solution and the precipitant aqueous solution are simultaneously introduced into the reactor, the reaction pH is controlled to maintain the first pH at 10.30-11.00, and the concentration of the reaction complexing agent is 0.5-10.0g / L; when the particle size of the reactant reaches the target particle size of the kernel of 3.0-7.0μm, the introduction of the ternary mixed metal salt solution, the complexing agent aqueous solution and the precipitant aqueous solution is stopped, and the kernel slurry after the reaction is pumped into a centrifuge for water washing, the washing time is 200-800, the washing temperature is 60-75°C, and the kernel filter cake is dried until the moisture content of the filter cake is 10-25% to obtain a kernel filter cake for standby use;

[0060] In the volume of 1~10m 3 The second reactor has a volume of 0.1 to 3 m 3 The concentrator is filled with pure water and circulated, and protective gas is introduced. The complexing agent aqueous solution and the precipitant aqueous solution are introduced to adjust the complexing agent concentration to 0.5-10.0 g / L and the second pH to 10.00-11.20, and the reaction temperature is controlled to 45-70°C. The input weight is [(aV / D 3 *d 3 ) / (1-s)]kg of inner core filter cake. Under the condition of the second stirring speed of 150-300rpm, the ternary mixed metal salt solution is pumped into the reactor at a flow rate of 30-600L / h, and the complexing agent aqueous solution, the precipitant aqueous solution and the inorganic aluminum alkali solution are simultaneously introduced into the reactor, the pumping flow rate of the inorganic aluminum alkali solution is controlled to be 2-100L / h, the reaction pH is controlled to maintain the second pH at 10.00-11.20, and the complexing agent concentration is 0.5-10.0g / L; the reaction stirring is reduced by 20rpm per hour from the second stirring speed to the third stirring speed of 30-100rpm in a stepwise manner; the reaction is stopped when the reactant particle size reaches the overall target particle size of 8-18μm.

[0061] The reacted material is transferred to an aging kettle and allowed to stand for 2 to 4 hours, after which the supernatant is removed and 0.5 to 5 m of a 32% strong alkali solution is added. 3 , stirring for 10 to 24 hours to dissolve the aluminum hydroxide in the outer core to form a porous and sparse structure; the material is washed and centrifuged at a temperature of 60 to 75°C, dried at 100 to 150°C, mixed, sieved, and iron removed to obtain a high-nickel ternary precursor with inner tightness and outer looseness. The internal compact structure size of the precursor is 3 to 7 μm, the particle size is 8.0 to 18.0 μm, the particle size distribution is 0.2 to 0.45, and the tap density is 1.8 to 2.3 g / cm3 , BET is 8~20m 2 / g.

[0062] Example 1

[0063] The molar ratio of nickel, cobalt and manganese inorganic salts is Ni 0.88 Co 0.09 Mn 0.03 (OH)2, a ternary mixed metal salt solution with a total metal (nickel, cobalt, and manganese) concentration of 2.0 mol / L; sodium aluminate is used to prepare an aluminum concentration of 0.20 mol / L, and sodium hydroxide is used to adjust the solution pH to 13.20 to obtain an inorganic aluminum alkali solution; a sodium hydroxide aqueous solution with a concentration of 10 mol / L is prepared; an ammonia aqueous solution with a concentration of 8.0 g / L is prepared;

[0064] In a volume of 1m 3 The first reactor has a volume of 0.2m 3 The concentrator is filled with pure water and circulated, and nitrogen is introduced for protection. The complexing agent aqueous solution and the precipitant aqueous solution are introduced to adjust the complexing agent concentration to 3.8g / L and the first pH to 10.80, and the reaction temperature is controlled to 60°C. Under the condition of a first stirring speed of 480pm, the ternary mixed metal salt solution is pumped into the reactor at a flow rate of 30L / h, and the complexing agent aqueous solution and the precipitant aqueous solution are introduced into the reactor at the same time, and the reaction pH is controlled to maintain the first pH at 10.80; when the particle size of the reactant reaches the target particle size of the kernel of 4.0μm, the introduction of the ternary mixed metal salt solution, the complexing agent aqueous solution and the precipitant aqueous solution is stopped, and the kernel slurry after the reaction is pumped into a centrifuge for water washing, the washing time is 300s, the washing temperature is 70°C, and the kernel filter cake is dried until the moisture content of the kernel filter cake is 15% to obtain the kernel filter cake for use;

[0065] In a volume of 1m 3 The second reactor has a volume of 0.2m 3 The concentrator is filled with pure water and circulated, and nitrogen is introduced as a protective gas. The complexing agent aqueous solution and the precipitant aqueous solution are introduced to adjust the complexing agent concentration to 3.8g / L and the second pH to 11.00, and the reaction temperature is controlled to 60°C. And a core filter cake weighing 17.5kg is added. Under the condition of a second stirring speed of 300rpm, the ternary mixed metal salt solution is pumped into the reactor at a flow rate of 50L / h, and the complexing agent aqueous solution, the precipitant aqueous solution and the inorganic aluminum alkali solution are simultaneously introduced into the reactor, and the pumping flow of the inorganic aluminum alkali solution is controlled to be 5L / h, and the reaction pH is controlled to maintain the second pH at 11.00; the reaction stirring is reduced by 20rpm per hour from the second stirring speed to the third stirring speed of 80rpm in a stepwise manner; the reaction is stopped when the particle size of the reactant reaches the overall target particle size of 12μm.

[0066] The reacted material was transferred to an aging kettle and allowed to stand for 3 hours, after which the supernatant was removed and 1 ml of a 32% strong alkali solution was added. 3 , and stirred for 12 hours to dissolve the aluminum hydroxide in the outer core to form a porous and sparse structure; the material was washed and centrifuged at 70°C, dried at 130°C, batch mixed, sieved, and iron removed to obtain an inner-tight and outer-loose high-nickel ternary precursor.

[0067] The ternary precursor material prepared in Example 1 of the present invention was subjected to scanning electron microscopy testing, and the test results are as follows: Figure 1-1 , Figure 1-2 As shown, it can be seen that the ternary precursor material prepared in Example 1 of the present invention has a compact structure of 3.86 microns in the center, and the outer core is a loose porous structure.

[0068] The D50 of the inner-tight and outer-loose high-nickel ternary precursor prepared in Example 1 of the present invention is 12.21 μm.

[0069] The particle size distribution of the inner-tight and outer-loose high-nickel ternary precursor prepared in Example 1 of the present invention is 0.42.

[0070] The tap density of the inner tight and outer loose high nickel ternary precursor prepared in Example 1 of the present invention is 1.94 g / cm 3 .

[0071] The BET of the inner tight outer loose high nickel ternary precursor prepared in Example 1 of the present invention is 12.68m 2 / g.

[0072] Example 2

[0073] The molar ratio of nickel, cobalt and manganese inorganic salts is Ni 0.90 Co 0.05 Mn 0.05 (OH)2, a ternary mixed metal salt solution with a total metal (nickel, cobalt, and manganese) concentration of 2.2 mol / L; sodium aluminate is used to prepare an aluminum concentration of 0.50 mol / L, and sodium hydroxide is used to adjust the solution pH to 13.00 to obtain an inorganic aluminum alkali solution; a sodium hydroxide aqueous solution with a concentration of 5 mol / L is prepared; and an ammonia aqueous solution with a concentration of 8.0 g / L is prepared;

[0074] In a volume of 10m 3 The first reactor has a volume of 2m 3The concentrator is filled with pure water and circulated, and nitrogen is introduced for protection. The complexing agent aqueous solution and the precipitant aqueous solution are introduced to adjust the complexing agent concentration to 4.5g / L and the first pH to 10.70, and the reaction temperature is controlled to 55°C. Under the condition of a first stirring speed of 250pm, the ternary mixed metal salt solution is pumped into the reactor at a flow rate of 400L / h, and the complexing agent aqueous solution and the precipitant aqueous solution are introduced into the reactor at the same time, and the reaction pH is controlled to maintain the first pH at 10.70; when the particle size of the reactant reaches the target particle size of the kernel of 6.50μm, the introduction of the ternary mixed metal salt solution, the complexing agent aqueous solution and the precipitant aqueous solution is stopped, and the kernel slurry after the reaction is pumped into a centrifuge for water washing, the water washing time is 300s, the water washing temperature is 70°C, and the kernel filter cake is dried until the moisture content of the kernel filter cake is 12% to obtain the kernel filter cake for use;

[0075] In a volume of 10m 3 The second reactor has a volume of 2m 3 The concentrator is filled with pure water and circulated, and nitrogen is introduced as protective gas. The complexing agent aqueous solution and the precipitant aqueous solution are introduced to adjust the complexing agent concentration to 4.5g / L and the second pH to 10.50, and the reaction temperature is controlled to be 55°C. And a core filter cake weighing 568kg is added. Under the condition of the second stirring speed of 160rpm, the ternary mixed metal salt solution is pumped into the reactor at a flow rate of 550L / h, and the complexing agent aqueous solution, the precipitant aqueous solution and the inorganic aluminum alkali solution are simultaneously introduced into the reactor, and the pumping flow of the inorganic aluminum alkali solution is controlled to be 22L / h, and the reaction pH is controlled to maintain the second pH at 10.50; the reaction stirring is reduced by 20rpm per hour from the second stirring speed to the third stirring speed of 40rpm in a step-by-step manner; the reaction is stopped when the reactant particle size reaches the overall target particle size of 14μm.

[0076] The reacted material was transferred to an aging kettle and allowed to stand for 2 hours, after which the supernatant was removed and 4 ml of 32% sodium hydroxide solution was added. 3 , stirring for 15 hours to dissolve the aluminum hydroxide in the outer core to form a porous and sparse structure; the material was washed and centrifuged at 70°C, dried at 130°C, mixed, sieved, and iron removed to obtain a high-nickel ternary precursor with inner tightness and outer looseness. The internal compact structure size of the precursor is 6.54μm, the particle size D50 is 14.12μm, the particle size distribution is 0.31, and the tap density is 2.01g / cm 3 , BET is 17.82m 2 / g.

[0077] The ternary precursor material prepared in Example 2 of the present invention was tested by scanning electron microscopy. The test results are as follows: Figure 2-1 , Figure 2-2 As shown, it can be seen that the ternary precursor material prepared in Example 2 of the present invention has a compact structure of 6.54 microns in the center, and the outer core is a loose porous structure.

[0078] Example 3

[0079] The molar ratio of nickel, cobalt and manganese inorganic salts is Ni 0.95 Co 0.03 Mn 0.02 (OH)2, a ternary mixed metal salt solution with a total metal (nickel, cobalt, and manganese) concentration of 1.60 mol / L; sodium aluminate is used to prepare an aluminum concentration of 0.50 mol / L, and sodium hydroxide is used to adjust the solution pH to 13.20 to obtain an inorganic aluminum alkali solution; a sodium hydroxide aqueous solution with a concentration of 5 mol / L is prepared; and an ammonia aqueous solution with a concentration of 8.0 g / L is prepared;

[0080] In a volume of 8m 3 The first reactor has a volume of 2m 3 The concentrator is filled with pure water and circulated, and nitrogen is introduced for protection. The complexing agent aqueous solution and the precipitant aqueous solution are introduced to adjust the complexing agent concentration to 2.2g / L and the first pH to 11.20, and the reaction temperature is controlled to 60°C. Under the condition of a first stirring speed of 420rpm, the ternary mixed metal salt solution is pumped into the reactor at a flow rate of 200L / h, and the complexing agent aqueous solution and the precipitant aqueous solution are introduced into the reactor at the same time, and the reaction pH is controlled to maintain the first pH at 11.20; when the particle size of the reactant reaches the target particle size of the kernel of 5.5μm, the introduction of the ternary mixed metal salt solution, the complexing agent aqueous solution and the precipitant aqueous solution is stopped, and the kernel slurry after the reaction is pumped into a centrifuge for water washing, the washing time is 300s, the washing temperature is 70°C, and the kernel filter cake is dried until the moisture content of the kernel filter cake is 18% to obtain the kernel filter cake for use;

[0081] In a volume of 8m 3 The second reactor has a volume of 2m 3 The concentrator is filled with pure water and circulated, and nitrogen is introduced as protective gas. The complexing agent aqueous solution and the precipitant aqueous solution are introduced to adjust the complexing agent concentration to 2.2g / L and the second pH to 10.30, and the reaction temperature is controlled to 60°C. And a core filter cake weighing 451.5kg is added. Under the condition of the second stirring speed of 360rpm, the ternary mixed metal salt solution is pumped into the reactor at a flow rate of 520L / h, and the complexing agent aqueous solution, the precipitant aqueous solution and the inorganic aluminum alkali solution are simultaneously introduced into the reactor, and the pumping flow of the inorganic aluminum alkali solution is controlled to be 30L / h, and the reaction pH is controlled to maintain the second pH at 10.30; the reaction stirring is reduced by 20rpm per hour from the second stirring speed to the third stirring speed of 50rpm in a step-by-step manner; the reaction is stopped when the reactant particle size reaches the overall target particle size of 13.50μm.

[0082] The reacted material was transferred to an aging kettle and allowed to stand for 3 hours, after which the supernatant was removed and 32% sodium hydroxide solution was added for 3 minutes. 3, stirring for 18 hours to dissolve the aluminum hydroxide in the outer core to form a porous and sparse structure; the material was washed and centrifuged at 70°C, dried at 130°C, mixed, sieved, and iron removed to obtain a high-nickel ternary precursor with inner tightness and outer looseness. The internal compact structure size of the precursor is 5.63μm, the particle size D50 is 13.65μm, the particle size distribution is 0.33, and the tap density is 1.96g / cm 3 , BET is 13.98m 2 / g.

[0083] The ternary precursor material prepared in Example 3 of the present invention was tested by scanning electron microscopy. The test results are as follows: Figure 3-1 , Figure 3-2 As shown, it can be seen that the ternary precursor material prepared in Example 3 of the present invention has a compact structure of 5.63 microns in the center, and the outer core is a loose porous structure.

[0084] Comparative Example 1

[0085] The molar ratio of nickel, cobalt and manganese inorganic salts is Ni 0.95 Co 0.03 Mn 0.02 (OH)2, a ternary mixed metal salt solution with a total metal (nickel, cobalt, and manganese) concentration of 1.60 mol / L; a sodium hydroxide aqueous solution with a concentration of 5 mol / L; and an ammonia aqueous solution with a concentration of 8.0 g / L;

[0086] In a volume of 8m 3 The first reactor has a volume of 2m 3 The concentrator is filled with pure water and circulated, and nitrogen is introduced for protection. The complexing agent aqueous solution and the precipitant aqueous solution are introduced to adjust the complexing agent concentration to 2.2g / L and the first pH to 11.20, and the reaction temperature is controlled to 60°C. Under the condition of a first stirring speed of 420rpm, the ternary mixed metal salt solution is pumped into the reactor at a flow rate of 200L / h, and the complexing agent aqueous solution and the precipitant aqueous solution are introduced into the reactor at the same time, and the reaction pH is controlled to maintain the first pH at 11.20; when the particle size of the reactant reaches the target particle size of the kernel of 5.5μm, the introduction of the ternary mixed metal salt solution, the complexing agent aqueous solution and the precipitant aqueous solution is stopped, and the kernel slurry after the reaction is pumped into a centrifuge for water washing, the washing time is 300s, the washing temperature is 70°C, and the kernel filter cake is dried until the moisture content of the kernel filter cake is 18% to obtain the kernel filter cake for use;

[0087] In a volume of 8m 3 The second reactor has a volume of 2m 3The concentrator is filled with pure water and circulated, and nitrogen is introduced as protective gas. The complexing agent aqueous solution and the precipitant aqueous solution are introduced to adjust the complexing agent concentration to 2.2g / L and the second pH to 10.30, and the reaction temperature is controlled to 60°C. And a core filter cake weighing 451.5kg is added. Under the condition of the second stirring speed of 360rpm, the ternary mixed metal salt solution is pumped into the reactor at a flow rate of 520L / h, and the complexing agent aqueous solution and the precipitant aqueous solution are simultaneously added, and the reaction pH is controlled to maintain the second pH at 10.30; the reaction stirring is reduced by 20rpm per hour from the second stirring speed to the third stirring speed of 50rpm in a stepwise manner; the reaction is stopped when the reactant particle size reaches the overall target particle size of 13.50μm.

[0088] The reacted material was transferred to an aging kettle and allowed to stand for 3 hours, after which the supernatant was removed and 32% sodium hydroxide solution was added for 3 minutes. 3 After stirring for 18 hours, the material was washed and centrifuged at 70°C, dried at 130°C, batch mixed, sieved, and iron removed to obtain a high-nickel ternary precursor with tight inside and loose outside.

[0089] The ternary precursor material prepared in comparative example 1 of the present invention was subjected to scanning electron microscopy test, and the test results are as follows: Figure 4-1 , Figure 4-2 As shown, it can be seen that the ternary precursor material prepared in Comparative Example 1 of the present invention presents a compact structure as a whole.

[0090] The D50 of the ternary precursor prepared in Comparative Example 1 of the present invention is 13.58 μm.

[0091] The particle size distribution of the ternary precursor prepared in Comparative Example 1 of the present invention is 0.34 μm.

[0092] The tap density of the ternary precursor prepared in Comparative Example 1 of the present invention is 2.06 g / cm 3 .

[0093] The BET of the ternary precursor prepared in Comparative Example 1 of the present invention is 5.85m 2 / g.

[0094] 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.

[0095] Comparative Example 2

[0096] The molar ratio of nickel, cobalt and manganese inorganic salts is Ni 0.95 Co 0.03 Mn 0.02(OH)2, a ternary mixed metal salt solution with a total metal (nickel, cobalt, and manganese) concentration of 1.60 mol / L; a sodium hydroxide aqueous solution with a concentration of 5 mol / L; and an ammonia aqueous solution with a concentration of 8.0 g / L;

[0097] In a volume of 8m 3 The first reactor has a volume of 2m 3 The concentrator is filled with pure water and circulated, and nitrogen is introduced for protection. The complexing agent aqueous solution and the precipitating agent aqueous solution are introduced to adjust the complexing agent concentration to 2.2g / L and the first pH to 11.20, and the reaction temperature is controlled to 60°C. Under the condition of a first stirring speed of 420rpm, the ternary mixed metal salt solution is pumped into the reactor at a flow rate of 200L / h, and the complexing agent aqueous solution and the precipitating agent aqueous solution are simultaneously introduced into the reactor, and the reaction pH is controlled to maintain the first pH at 11.20; after the particle size reaches 5.5 microns, the stirring speed is adjusted to a second stirring speed of 360rpm, and the ternary mixed metal salt solution is adjusted to a flow rate of 520L / h and pumped into the reactor, and the reaction pH is controlled to be adjusted to a second pH of 10.30; the reaction stirring is reduced by 20rpm per hour from the second stirring speed to the third stirring speed of 50rpm in a stepwise manner; the reaction is stopped when the reactant particle size reaches the overall target particle size of 13.50μm.

[0098] The reacted material was transferred to an aging kettle and allowed to stand for 3 hours, after which the supernatant was removed and 32% sodium hydroxide solution was added for 3 minutes. 3 After stirring for 18 hours, the material was washed and centrifuged at 70°C, dried at 130°C, batch mixed, sieved, and iron removed to obtain a high-nickel ternary precursor with tight inside and loose outside.

[0099] The ternary precursor material prepared in Comparative Example 2 of the present invention was subjected to scanning electron microscopy testing, and the test results are as follows: Figure 5-1 , Figure 5-2 As shown, it can be seen that the ternary precursor material prepared in Comparative Example 2 of the present invention presents a compact structure as a whole, and the particles have obvious spherical cracking phenomenon.

[0100] The D50 of the ternary precursor prepared in Comparative Example 2 of the present invention is 13.63 μm.

[0101] The particle size distribution of the ternary precursor prepared in Comparative Example 2 of the present invention is 0.36 μm.

[0102] The tap density of the ternary precursor prepared in Comparative Example 2 of the present invention is 2.11 g / cm 3 .

[0103] The BET of the ternary precursor prepared in Comparative Example 2 of the present invention is 4.61m 2 / g.

[0104] 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 an inner tight and outer loose high nickel ternary precursor, characterized in that: The steps include: (1) preparing a ternary mixed metal salt solution using nickel, cobalt and manganese inorganic salts; preparing an inorganic aluminum base solution; preparing a precipitant aqueous solution; and preparing a complexing agent aqueous solution; (2) filling the first reaction kettle and the first concentrator with pure water and circulating the water, introducing a protective gas, introducing a complexing agent aqueous solution and a precipitant aqueous solution to adjust the complexing agent concentration and the first pH, and controlling the reaction temperature; At a first stirring speed, the ternary mixed metal salt solution, the complexing agent aqueous solution and the precipitant aqueous solution are simultaneously introduced into the reaction kettle, and the reaction pH is controlled to maintain a first pH; When the particle size of the reactants reaches the target particle size of the kernel, the feed liquid is stopped, and the kernel slurry after the reaction is pumped into a centrifuge for washing and drying to obtain a kernel filter cake; (3) Filling the second reactor and the second concentrator with pure water and circulating it, introducing protective gas, introducing a complexing agent aqueous solution and a precipitant aqueous solution to adjust the complexing agent concentration and the second pH, controlling the reaction temperature, and adding a certain amount of kernel filter cake; Under the condition of the second stirring speed, the ternary mixed metal salt solution, the complexing agent aqueous solution, the precipitant aqueous solution and the inorganic aluminum base solution are simultaneously introduced into the reaction kettle, the reaction pH is controlled to maintain the second pH, and the reaction stirring is stepped down from the second stirring speed to the third stirring speed; The reaction is stopped when the particle size of the reactants reaches the overall target particle size; (4) transferring the reacted material to an aging kettle, allowing it to stand, removing the supernatant, adding a strong alkaline solution and stirring; and obtaining an inner-tight and outer-loose high-nickel ternary precursor after post-treatment.

2. The method for preparing a high-nickel ternary precursor with tight inside and loose outside according to claim 1, characterized in that: In the step (1), the nickel, cobalt and manganese inorganic salts are one or more of the corresponding sulfates, nitrates and chlorides, the total metal concentration in the ternary mixed metal salt solution is 1.0 to 2.3 mol / L, and the ratio of nickel, cobalt and manganese in the ternary mixed metal salt solution conforms to the formula Ni x Co y Mn (1-x-y) (OH)2, where 0 <x<0.98,0<y<0.40。 3. The method for preparing a high-nickel ternary precursor with tight inside and loose outside according to claim 1, characterized in that: The inorganic aluminum in the inorganic aluminum alkali solution in step (1) is one or more of sodium aluminate and aluminum sulfate; the aluminum concentration in the inorganic aluminum alkali solution is 0.10-1.0 mol / L, the alkali is one or more of sodium hydroxide and potassium hydroxide, and the pH value is 13.00-13.

50.

4. The method for preparing a high-nickel ternary precursor with tight inside and loose outside according to claim 1, characterized in that: In the step (1), the precipitant is one or more of sodium hydroxide and potassium hydroxide, and the concentration of the precipitant aqueous solution is 5.0-12.0 mol / L.

5. The method for preparing a high-nickel ternary precursor with tight inside and loose outside according to claim 1, characterized in that: In the step (1), the complexing agent is one or more of ammonia water, ammonium sulfate, sodium ascorbate, salicylic acid, and oxalic acid, and the concentration of the complexing agent aqueous solution is 1.0 to 11.0 g / L.

6. The method for preparing a high-nickel ternary precursor with tight inside and loose outside according to claim 1, characterized in that: In the step (2), the reaction temperature of the first reactor is 45-70°C; the concentration of the reaction complexing agent is 0.5-10.0 g / L; the first pH of the reaction is 10.30-11.00; the first stirring speed is 200-540 rpm; the pumping flow rate of the ternary mixed metal salt solution is 30-600 L / h; and the target particle size of the kernel is 3.0-7.0 μm.

7. The method for preparing a high-nickel ternary precursor with tight inside and loose outside according to claim 1, characterized in that: In the step (2), the centrifuge washing time is 200 to 800 seconds; the moisture content of the inner core filter cake is 10 to 25%.

8. The method for preparing a high-nickel ternary precursor with tight inside and loose outside according to claim 1, characterized in that: The reaction temperature of the second reaction kettle in step (3) is 45-70°C; the concentration of the complexing agent is 0.5-10.0 g / L; the second pH of the reaction is 10.00-11.20; the weight of the kernel filter cake added is (aV / D 3 *d 3 )kg; the second stirring speed is 150-300rpm, the third stirring speed is 30-100rpm; the pumping flow rate of the ternary mixed metal salt solution is 30-600L / h; the pumping flow rate of the inorganic aluminum base solution is 2-100L / h; the overall target particle size is 8-18μm.

9. The method for preparing a high-nickel ternary precursor with tight inside and loose outside according to claim 1, characterized in that: The strong base added in step (4) is at least one of sodium hydroxide and potassium hydroxide, and the added volume is 0.5 to 5 m 3 , stirring time is 10 to 24 hours.

10. A high-nickel ternary precursor with tight inside and loose outside prepared by the preparation method according to any one of claims 1 to 9.

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