CN112582605A - Preparation method of nickel-cobalt-manganese ternary precursor for reducing sulfur content in continuous production process - Google Patents

Preparation method of nickel-cobalt-manganese ternary precursor for reducing sulfur content in continuous production process Download PDF

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CN112582605A
CN112582605A CN202011352509.4A CN202011352509A CN112582605A CN 112582605 A CN112582605 A CN 112582605A CN 202011352509 A CN202011352509 A CN 202011352509A CN 112582605 A CN112582605 A CN 112582605A
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slurry
concentration
reaction kettle
kettle
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CN112582605B (en
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安孝坤
张洁
刘逸群
陈睿
贺克宝
董林涛
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Wanhua Chemical Group Co Ltd
Wanhua Chemical Sichuan Co Ltd
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Wanhua Chemical Sichuan Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
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    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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Abstract

The invention discloses a preparation method of a nickel-cobalt-manganese ternary precursor with reduced sulfur content in a continuous production process, which comprises the steps of injecting slurry into a washing kettle after concentration by a concentrator, washing off sulfur impurities on the surface of the precursor by hot alkali, then injecting the slurry into a reaction kettle again after concentration by the concentrator, and continuously growing precursor particles to a target diameter; wherein, the volume of the slurry in the reaction kettle is reduced after concentration, alkaline washing and concentration, at the moment, a complexing agent with the same concentration as the ammonia in the reaction bottom liquid is injected from V4, and the pH value of the reaction is automatically adjusted by a feedback system to be stable. The preparation method of the invention reduces SO of the solution in the reaction kettle4 2‑Concentration and washing off SO on the surface of the particles in the process of growing up4 2‑Thereby greatly reducing sulfur encapsulated in the interior of the granulesImpurity content, and simultaneously improves the crystallinity and true density of the precursor.

Description

Preparation method of nickel-cobalt-manganese ternary precursor for reducing sulfur content in continuous production process
Technical Field
The invention belongs to the technical field of preparation of ternary precursors of lithium ion batteries, and particularly relates to a preparation method of a nickel-cobalt-manganese ternary precursor with low sulfur content.
Background
Due to excellent electrochemical performance, the lithium ion battery is widely applied to the fields of 3C, electric automobiles, electric tools, energy storage, wearable electronic products and the like. The ternary nickel-cobalt-manganese anode material is a lithium ion battery anode material with excellent performances in all aspects, the ternary precursor is a main raw material for producing the ternary anode material, and the particle size distribution, the morphology, the impurity content and the like of the precursor are closely related to the physical and chemical properties of the anode material.
The coprecipitation method is the main method for producing the precursor industrially at present, and the adopted salt raw material is sulfate. There is a large amount of SO in the synthesis process4 2-The sulfate radical on the surface of the precursor can be removed by washing with hot alkali or hot pure water, and the crystallinity of the precursor can be damaged by excessive alkali washing, so that the product quality is poor. For example, CN107459069B and CN103342395B disclose methods for reducing sulfur content by alkali washing after removing mother liquor from precursors, but the method for washing the surface of the precursor final product by alkali washing only can wash away sulfur impurities on the surface, and is difficult to wash away SO wrapped in the particles4 2-. Generally, sulfur impurities wrapped inside are also high, for a precursor with high S impurity content, the cycle performance of the obtained anode material is poor after sintering, the capacity is low, and the produced lithium ion battery cannot meet the market requirement.
CN107611383B and CN110817975B disclose methods for removing supernatant liquid and then reducing the sulfur content in the precursor by alkaline washing the filter cake, mainly reducingSO in supernatant4 2-The content of S impurities in the precursor is reduced, but the method still cannot effectively reduce SO coated in the particles4 2-。
Therefore, a method is still needed, which can effectively reduce the content of S impurities in the precursor and on the surface of the precursor, and can avoid excessive alkali washing, so as to improve the crystallinity of the precursor and improve the cycle performance of the cathode material.
Disclosure of Invention
The invention aims to provide a preparation method of a nickel-cobalt-manganese ternary precursor for reducing sulfur content in a continuous production process, aiming at overcoming the defects of the prior art, so that the S impurity content in the interior and on the surface of the precursor can be effectively reduced, and the crystallinity of the ternary precursor can be effectively improved.
In order to achieve the purpose, the invention adopts the following technical scheme:
a preparation method of a nickel-cobalt-manganese ternary precursor for reducing sulfur content in a continuous production process comprises the steps of taking sulfates of nickel, cobalt and manganese, alkali and a complexing agent as raw materials, synthesizing the ternary precursor to a target granularity in a reaction kettle through coprecipitation, and aging, washing, drying and sieving to obtain a ternary precursor material, and is characterized in that the synthesis of the precursor is divided into two stages:
1) a nucleation stage: forming a large amount of micro particles by adopting high pH, high stirring speed and low feeding speed;
2) and (3) growth stage: the particles grow up rapidly by adopting low pH, low stirring speed and high feeding speed;
wherein, the particle size distribution is detected every 1 hour in the growth stage, and the alkali washing operation is carried out according to the size of the volume particle size distribution D50; preferably, the alkaline washing operation comprises the following steps:
s1, stopping feeding of sulfate, alkali and a complexing agent, concentrating the slurry discharged from the reaction kettle in a concentrator 1, discharging clear liquid, increasing the solid content of the slurry, and discharging SO in the solution4 2-；
S2, pumping the concentrated slurry into a washing kettle, and stirring by using thermokaliteWashing the surface of the spherical particles to remove SO on the surface of the particles4 2-Removing;
s3, pumping the washed slurry into a thickener 2 through a pump, filtering the redundant clear liquid of the slurry, pumping the filtered slurry into the reaction kettle again, and continuously growing the small spherical particles returned to the reaction kettle through coprecipitation reaction.
In a specific embodiment, after the slurry is concentrated, washed with alkali and concentrated and returned to the reaction kettle, a complexing agent with the same concentration as that of the reaction condition is immediately injected into the reaction kettle, the pH value of the reaction is automatically adjusted by a feedback system to maintain stable, and then the slurry is fed again to ensure that the small spherical particles returned to the reaction kettle continue to grow.
In a particular embodiment, the base in the feedstock is selected from any one of NaOH or KOH, preferably NaOH; the complexing agent is selected from any one or more of ammonia water, urea, ammonium acetate, ammonium sulfate, ammonium carbonate, ammonium chloride and ammonium nitrate, and preferably ammonia water.
In a specific embodiment, the pH value of the reaction kettle system in the nucleation stage is 11.5-12.0, the stirring speed is 800-; and finishing the nucleation stage after the volume particle size distribution D50 of the precursor reaches 3 mu m.
In a specific embodiment, the pH value of the growth stage reaction kettle system is 10.0-11.5, the stirring speed is 200-800rpm, and the feeding speed of the salt solution is 3-8L/h; and after the volume particle size distribution D50 of the precursor reaches 10 mu m, ending the growth stage and beginning aging.
In a specific embodiment, the particle size distribution is measured every 1 hour during the growth phase, and a hot alkaline washing operation is performed every 2 μm to 3 μm increase according to the particle volume particle size distribution D50 until the particles grow to the target particle size.
In a preferred embodiment, the growth phase comprises a first growth phase and a second growth phase, the pH of the reaction kettle system of the first growth phase is 11.0-11.5, the stirring speed is 500-800rpm, and the feeding speed of the salt solution is 3-5L/h; starting alkali washing operation after the first stage, and ending the first growth stage after the volume particle size distribution D50 of the precursor reaches 7 mu m; preferably, after the first growth stage is finished, the reaction enters a second growth stage, the alkali washing operation is continued, the pH value of the reaction kettle system is 10.0-11.0, the stirring rotation speed is 200-500rpm, and the salt solution feeding speed is 5-8L/h; and after the volume particle size distribution D50 of the precursor reaches 10 mu m, ending the growth stage and beginning aging.
In a particular embodiment, the thermal base is selected from any one of sodium hydroxide, potassium hydroxide, barium hydroxide, preferably sodium hydroxide; the temperature of the hot alkali is 40-90 ℃, preferably 50-60 ℃; the concentration of the sodium hydroxide solution is 1-10 mol/L, preferably 2-4 mol/L.
In a specific embodiment, the pH value of the reaction bottom liquid is 11-13, preferably 11.2-11.9, the ammonia concentration is 0.2-0.6mol/L, preferably 0.25-0.5, the reaction temperature is 40-70 ℃, preferably 50-60 ℃, the rotation speed of a stirring paddle is 50-800rpm, preferably 400-800rpm, and the feeding speed of a salt solution is 1L/h-8L/h, preferably 3L/h-6L/h.
In a specific embodiment, the concentration kettle is a device with a stirring function, which can discharge clear slurry liquid and leave solid phase in the kettle to improve the solid content of the slurry.
In a specific embodiment, the nickel-cobalt-manganese ternary precursor has the chemical formula of NixCoyMnz(OH)2Wherein x + y + z is 1, and x is more than 0.20 and less than 0.90, y is more than 0.05 and less than 0.40, and z is more than 0.05 and less than 0.40.
Compared with the prior art, the invention has the following beneficial effects:
in the invention, in the synthesis process of the precursor, the particle size of the precursor grows to different stages, and hot alkali is continuously used for washing the surface of precipitate particles to ensure that SO is generated4 2-Removing; and the complexing agent with the same reaction condition is continuously used for replacing the clear liquid in the reaction kettle, SO that the SO in the reaction kettle is effectively reduced4 2-Content of preventing SO in the particles during growth4 2-The coating is coated inside the particles, so that S impurities inside the particles are reduced, and the problem that the S impurities of the precursor product exceed the standard is solved. At the same time, the preparation method of the invention is also discovered unexpectedly by controlling the time of alkaline washing and the concentration of the alkaline solutionThe problem of poor crystallinity of the precursor caused by excessive alkali washing can be solved, and the ternary precursor material with good crystallization property and high true density can be obtained.
Drawings
FIG. 1 is a schematic process flow diagram of the preparation method of the present invention.
Fig. 2 is an XRD spectrum of the ternary precursor prepared in example 1 and comparative example 3.
FIG. 3 is an SEM image of ternary precursors prepared in example 1 (right) and comparative example 3 (left) of the present invention.
Wherein, 1-reaction kettle, 2 concentration kettle A, 3 washing kettle, 4 concentration kettle B, 5 pump, 6 feed line, 7 concentration component, 8 thermokalite.
Detailed Description
The following examples will further illustrate the method provided by the present invention in order to better understand the technical solution of the present invention, but the present invention is not limited to the listed examples, and should also include any other known modifications within the scope of the claims of the present invention.
As shown in fig. 1, the preparation method of the nickel-cobalt-manganese ternary precursor with reduced sulfur content in the continuous production process of the present invention comprises the steps of carrying out coprecipitation reaction of the ternary precursor in a reaction kettle 1 with a stirring device, including a nucleation step and a growth step, growing to a certain stage, transferring the reaction solution to a concentration kettle a2, wherein the concentration kettle a2 comprises a concentration member 7, separating clear solution by concentration, transferring slurry to a washing kettle 3, feeding the high-solid ternary precursor slurry into the washing kettle 3 through hot alkali 8, transferring the slurry into a concentration kettle B4 for further concentration after hot alkali washing, returning the concentrated slurry to the reaction kettle 1 again, adding raw materials with the same concentration as the original reaction solution through a feeding pipeline 6 for continuous growth, and repeating the concentration, washing and concentration steps according to different stages of growth. The process of the specific preparation method is further described as follows:
1) preparing nickel sulfate, cobalt sulfate, manganese sulfate and pure water into a salt solution with a certain concentration.
2) And adding the mixed salt solution, the complexing agent and the sodium hydroxide solution into a reaction kettle which is continuously stirred, and carrying out coprecipitation reaction to obtain the nickel-cobalt-manganese ternary precursor.
Further, a reaction bottom liquid is required to be prepared before the reaction starts, the reaction bottom liquid can be 1/2-2/3 of the effective volume of the reaction kettle, and the pH value and the ammonia concentration of the reaction bottom liquid are the same as those of the reaction conditions. Generally, the reaction base solution is sodium hydroxide solution and ammonia solution, the concentration of which is not limited at all, the main function is to provide an initial growth environment for ternary precursor coprecipitation, and the pH of the reaction base solution is generally adjusted to be in the range of 11-13, preferably 11.2-11.9. For example, the concentration of the sodium hydroxide solution used for preparing the reaction base solution is 4 to 10mol/L, and the concentration of the aqueous ammonia solution is 0.2 to 0.6mol/L, preferably 0.25 to 0.5 mol/L; the temperature of the reaction bottom liquid is set to 40-70 ℃, preferably 50-60 ℃.
3) The first stage of the reaction is a nucleation stage, the reaction pH value is high, the stirring speed is high, the feeding speed is low, a large number of small crystal nuclei are formed in the reaction kettle, and then the small crystal nuclei are agglomerated into 3 mu m micro spherical particles. The second stage of the reaction is a growth stage, the pH value of the reaction is reduced, the stirring speed is reduced, the salt feeding speed is increased, and the growth of the tiny spherical particles is promoted. During the growth of the particles, the particle size distribution was measured every 1 hour using a laser particle sizer. According to different required levels of S impurity content, alkali washing operation can be carried out when the volume particle size distribution D50 grows to different stages.
Further, the pH value of the reaction kettle system in the nucleation stage is 11.5-12.0, the stirring rotation speed is 800-1500rpm, and the salt solution feeding speed is 1-3L/h; after the volume particle size distribution D50 of the precursor reaches 3 mu m, the nucleation stage is finished; the pH value of the growth stage reaction kettle system is 10.0-11.5, the stirring rotating speed is 200-800rpm, and the salt solution feeding speed is 3-8L/h; and after the volume particle size distribution D50 of the precursor reaches 10 mu m, ending the growth stage and beginning aging.
Furthermore, the growth stage comprises a first growth stage and a second growth stage, the pH value of the reaction kettle system of the first growth stage is 11.0-11.5, the stirring rotation speed is 500-800rpm, and the feeding speed of the salt solution is 3-5L/h; starting alkali washing operation after the first stage, and ending the first growth stage after the volume particle size distribution D50 of the precursor reaches 7 mu m; preferably, after the first growth stage is finished, the reaction enters a second growth stage, the alkali washing operation is continued, the pH value of the reaction kettle system is 10.0-11.0, the stirring rotation speed is 200-500rpm, and the salt solution feeding speed is 5-8L/h; and after the volume particle size distribution D50 of the precursor reaches 10 mu m, ending the growth stage and beginning aging.
4) Stopping feeding of sulfate, alkali and a complexing agent during alkaline washing, concentrating slurry discharged from the reaction kettle in a concentrator A, discharging clear liquid, increasing the solid content of the slurry, and discharging SO in the solution4 2-. The concentrated slurry is injected into a washing kettle, and under the stirring action, hot alkali of 40-90 ℃ is used for scouring the surface of spherical particles to remove SO on the surface of the particles4 2-And (5) removing.
The concentration kettle A, B is a device with stirring function and concentration component, which can discharge slurry clear liquid, leave solid phase in the kettle and improve solid content of slurry. Specifically, for example, the concentrating member is a hollow fiber membrane.
5) And after the hot alkali washing is finished, the slurry in the hot alkali tank is pumped into a thickener B through a diaphragm pump, redundant clear liquid of the slurry is filtered and then pumped into the reaction kettle again, and after all the slurry in the reaction kettle is concentrated, alkali washed and concentrated, the solid content is very high, so that the dispersion in the particle growth process in the kettle is not facilitated. And at the moment, a complexing agent with the same concentration as that of the reaction condition is injected into the reaction kettle through a complexing agent replenishing port of the feeding pipeline, the pH value in the kettle is controlled by a pH automatic adjusting feedback system to be kept stable, when the volume of the slurry in the kettle reaches 1/2-2/3 of the effective volume, the sulfate, alkali and the complexing agent are restarted for feeding, and the small spherical particles returning to the reaction kettle continue to grow up through coprecipitation reaction.
During the growth of the particles, the SO on the surface of the particles is washed away by hot alkali for a plurality of times4 2-Simultaneously, the complexing agent is added to replace the reaction solution, SO in the clear liquid is reduced4 2-The content of S impurities coated inside during the growth of the particles can be greatly reduced.
Further, the particle size distribution is detected every 1 hour in the growth stage, and hot alkali washing operation is performed every 2-3 μm according to the particle volume particle size distribution D50 until the particles grow to a target particle size, for example, more than 10 μm, which can be specifically determined according to the downstream customer requirements.
6) And stopping feeding and starting an aging reaction when the particle size of the precipitate reaches the target particle size, and washing, drying and sieving to obtain the ternary precursor material after the completion of the aging reaction.
Wherein, the aging, washing, drying, sieving and the like are all conventional operations in the field, and refer to the post-treatment process of the ternary precursor material in the prior art, such as aging for 4h, washing for 2-3 times by deionized water, drying at 120 ℃, and sieving to obtain the ternary precursor material with the required target particle size D50. The chemical formula of the nickel-cobalt-manganese ternary precursor can be expressed as NixCoyMnz(OH)2Wherein x + y + z is 1, and x is more than 0.20 and less than 0.90, y is more than 0.05 and less than 0.40, and z is more than 0.05 and less than 0.40.
The preparation process according to the invention is further illustrated, without any limitation, by the following more specific examples.
The following examples and comparative examples used the following main raw materials:
NiSO nickel sulfate hexahydrate4·6H2O, battery grade, jinchuan group;
cobalt sulfate heptahydrate CoSO4·7H2O, battery grade, cobalt friendly industry;
manganese sulfate monohydrate MnSO4·H2O, battery grade, new materials ltd, assembled by dazohong, Guizhou;
polyvinylidene fluoride (PVDF), analytically pure, alatin;
ammonia, analytically pure, alatin;
ammonium bicarbonate, analytically pure, alatin.
The related performance test method of the ternary precursor material is as follows:
electrochemical test equipment, a Shenzhen New Wei button cell test system;
roasting equipment, namely a combined fertilizer department crystal tube type furnace with the model of OTF-1500X;
an inorganic chemical product crystal structure analysis X-ray diffraction method (GB/T30904-2014);
the method for measuring the physical and mechanical properties of coal and rock comprises the following steps: coal and rock true density determination methods (GB/T23561.2-2009);
ICP test method (EPA 6010D-2014).
The invention is further illustrated, but not limited, by the following more specific examples.
Example 1:
(1) firstly, preparing 50L of reaction base solution by using ammonia water and sodium hydroxide, enabling the pH of the prepared reaction base solution to be 11.7 and the ammonia concentration to be 0.4mol/L, heating the reaction base solution by using jacket water bath to enable the temperature to be 60 ℃, and introducing nitrogen to carry out oxygen removal treatment on the reaction base solution. The method comprises the steps of simultaneously injecting a nickel-cobalt-manganese sulfate solution, ammonia water and sodium hydroxide into a 100L reaction kettle, setting the stirring speed to be 1000rpm, the temperature of a reaction system to be 60 ℃, the ammonia concentration in the reaction kettle to be 0.4mol/L and the pH value to be 11.7, wherein the molar ratio of nickel, cobalt and manganese in a mixed salt solution is 6:1:3, the concentration of the mixed salt solution is 2mol/L, the mass percent of a raw material sodium hydroxide solution is 32%, the ammonia concentration of a raw material solution is 4.1mol/L, and the ammonia concentration of a make-up solution is 0.4 mol/L.
(2) The reaction is started to be a nucleation stage, a metal salt solution, a sodium hydroxide solution and ammonia water are injected into a reaction kettle through an electric diaphragm pump, the flow rate of the metal salt solution is 2L/h, the water flow rate of raw material liquid ammonia is 0.3L/h, the flow rate of the sodium hydroxide solution is automatically adjusted through a feedback control system to control the pH to be 11.7, the rotating speed of a stirring paddle is 1000rpm, the particle size distribution is tested by a laser particle sizer every 1 hour, and the nucleation stage is ended after the volume particle size distribution D50 reaches 3 mu m.
(3) After the nucleation is finished, the reaction enters a first stage of nuclear growth, a metal salt solution, a sodium hydroxide solution and ammonia water are injected into a reaction kettle through an electric diaphragm pump, the flow rate of the metal salt solution is increased to 4L/h, the flow rate of raw material liquid ammonia is increased to 0.6L/h, the flow rate of the sodium hydroxide solution is automatically adjusted through a feedback control system to control the pH value to be 11.3, the rotating speed of a stirring paddle is reduced to 700rpm, the particle size distribution of particles is tested every 1 hour by using a laser particle sizer, and when the particle volume particle size distribution D50 reaches 4 mu m, the metal salt solution, the ammonia water and the hydrogen hydroxideFeeding a sodium solution, opening a liquid outlet of a reaction kettle, discharging slurry with the volume of 1/2 in the kettle into a concentration kettle 1, discharging clear liquid through concentration operation, pumping the concentrated slurry into a washing kettle by using a pneumatic diaphragm pump, stirring and washing by using hot alkali of 2mol/L sodium hydroxide at 50 ℃ for 20min to remove SO on the surfaces of particles4 2-Discharging the residual slurry in the reaction kettle into a concentration kettle 1 for concentration operation, pumping the slurry into a concentration kettle 2 by using a pneumatic diaphragm pump after hot alkali washing in a washing kettle is finished, and pumping the slurry into the reaction kettle again after removing the redundant alkali liquor; through twice concentration, alkali washing and concentration operations, the volume of slurry in the reaction kettle is reduced, 0.4mol/L ammonia water is injected into the reaction kettle through a liquid supplementing hole, meanwhile, the pH value in the kettle is controlled to be maintained at 11.2 by a pH automatic adjusting feedback system, when the volume of the slurry in the kettle reaches 50L of the effective volume of the reaction kettle, the liquid supplementing is stopped, the feeding of a metal salt solution, a sodium hydroxide solution and the ammonia water is restarted, and the small spherical particles returned to the reaction kettle continue to grow up through coprecipitation reaction.
(4) When the volume particle size distribution D50 reaches 7 mu m, the reaction enters a second stage of nuclear growth, a metal salt solution, a sodium hydroxide solution and ammonia water are injected into the reaction kettle through an electric diaphragm pump, the flow rate of the metal salt solution is increased to 6L/h, the flow rate of the raw material liquid ammonia is increased to 0.9L/h, the flow rate of the sodium hydroxide solution is automatically adjusted through a feedback control system to control the pH value to be 10.8, the rotating speed of a stirring paddle is reduced to 400rpm to ensure that the growth speed of spherical particles is kept relatively stable, and the alkaline washing operation in the step 3 is also carried out in the process.
(5) The concentration, alkali washing and concentration operations are carried out once for every 2 mu m increase of the particle volume and particle size distribution D50.
(6) And after the particle size reaches 10 mu m, aging the slurry in the reaction kettle for 4 hours, then putting the slurry into a hot alkali washing kettle for alkali washing, then putting the slurry into a centrifuge for washing by using pure water, demagnetizing the washed material, drying and sieving to obtain the product.
(7) Weighing 120g of LiOH and 456g of Ni (OH) according to the proportion that nLi to n (Ni + Co + Mn) is 1:12@Co(OH)2@Mn(OH)2Mixing completely, placing in a tube furnace, introducing oxygen, heating to 400 deg.C at a speed of 10 deg.C/min, and maintainingHeating for 1h, then heating to 820 ℃ at the same heating rate, preserving the heat for 12h, cooling the tube furnace, taking out the sample, and obtaining the lithium ion battery anode material LiNiO2@LiCoO2@LiMnO2。
Example 2:
the other operations were completely the same as those of example 1, except that in the step (5), concentration, alkali washing and concentration were carried out once for every 2 μm increase in the particle volume particle size distribution D50, and concentration, alkali washing and concentration were carried out once for every 3 μm increase in the particle volume particle size distribution D50.
Example 3:
(1) firstly, 50L of reaction base solution is prepared by ammonia water and sodium hydroxide, so that the pH value of the reaction base solution is 11.5, the ammonia concentration is 0.4mol/L, the reaction base solution is heated by jacket water bath at the temperature of 60 ℃, and the reaction base solution is deoxygenated by introducing nitrogen. The method comprises the steps of simultaneously injecting a nickel-cobalt-manganese sulfate solution, ammonia water and sodium hydroxide into a 100L reaction kettle, setting the stirring speed to be 1000rpm, setting the temperature of a reaction system to be 60 ℃, the ammonia concentration to be 0.4mol/L, the sodium hydroxide concentration to be 10mol/L and the pH value to be 11.5, wherein the molar ratio of nickel, cobalt and manganese in the mixed salt solution is 6:1:3, the concentration of the mixed salt solution is 2mol/L, the mass percent of the sodium hydroxide solution is 32%, the ammonia water concentration of a raw material solution is 4.1mol/L, and the ammonia water concentration of a make-up solution is 0.4 mol/L.
(2) The reaction is started to be a nucleation stage, a metal salt solution, a sodium hydroxide solution and ammonia water are injected into a reaction kettle through an electric diaphragm pump, the flow rate of the metal salt solution is 1L/h, the water flow rate of raw material liquid ammonia is 0.15L/h, the flow rate of the sodium hydroxide solution is automatically adjusted through a feedback control system to control the pH value to be 11.5, the rotating speed of a stirring paddle is 800rpm, the particle size distribution is tested by a laser particle sizer every 1 hour, and the nucleation stage is ended after the volume particle size distribution D50 reaches 3 mu m.
(3) After the nucleation is finished, the reaction enters a first stage of nuclear growth, a metal salt solution, a sodium hydroxide solution and ammonia water are injected into the reaction kettle through an electric diaphragm pump, the flow of the metal salt solution is increased to 3L/h, the flow of the raw material liquid ammonia is increased to 0.45L/h, the pH is controlled to be 11.0 by automatically adjusting the flow of the sodium hydroxide solution through a feedback control system, the rotating speed of a stirring paddle is reduced to 500rpm, and the method is beneficial to the nuclear growthTesting the particle size distribution once every 1 hour by using a laser particle size analyzer, stopping feeding of a metal salt solution, ammonia water and a sodium hydroxide solution when the particle volume particle size distribution D50 reaches 4 mu m, opening a liquid discharge port of a reaction kettle, discharging slurry with the volume of 1/2 in the kettle into a concentration kettle 1, discharging clear liquid through concentration operation, pumping the concentrated slurry into a washing kettle by using a pneumatic diaphragm pump, stirring and washing for 20min by using hot alkali with the temperature of 50 ℃ of 2mol/L sodium hydroxide to remove SO on the surfaces of particles4 2-Discharging the residual slurry in the reaction kettle into a concentration kettle 1 for concentration operation, pumping the slurry into a concentration kettle 2 by using a pneumatic diaphragm pump after hot alkali washing in a washing kettle is finished, and pumping the slurry into the reaction kettle again after removing the redundant alkali liquor; through twice concentration, alkali washing and concentration operations, the volume of slurry in the reaction kettle is reduced, 0.4mol/L ammonia water is injected into the reaction kettle through a liquid supplementing hole, meanwhile, the pH value in the kettle is controlled to be maintained at 11.0 by a pH automatic adjusting feedback system, when the volume of the slurry in the kettle reaches 50L of the effective volume of the reaction kettle, the liquid supplementing is stopped, the feeding of a metal salt solution, a sodium hydroxide solution and the ammonia water is restarted, and the small spherical particles returned to the reaction kettle continue to grow up through coprecipitation reaction.
(4) When the volume particle size distribution D50 reaches 7 mu m, the reaction enters a second stage of nuclear growth, a metal salt solution, a sodium hydroxide solution and ammonia water are injected into the reaction kettle through an electric diaphragm pump, the flow rate of the metal salt solution is increased to 5L/h, the flow rate of the raw material liquid ammonia is increased to 0.75L/h, the flow rate of the sodium hydroxide solution is automatically adjusted through a feedback control system to control the pH value to be 10.5, the rotating speed of a stirring paddle is reduced to 200rpm to ensure that the growth speed of spherical particles is kept relatively stable, and the alkaline washing operation in the step 3 is also carried out in the process.
(5) The concentration, alkali washing and concentration operations are carried out once for every 2 mu m increase of the particle volume and particle size distribution D50.
(6) And after the particle size reaches 10 mu m, aging the slurry in the reaction kettle for 4 hours, then putting the slurry into a hot alkali washing kettle for alkali washing, then putting the slurry into a centrifuge for washing by using pure water, demagnetizing the washed material, drying and sieving to obtain the product.
(7) Weighing 120g of LiOH and 456g of Ni (Mn) according to the proportion that nLi to n (Ni + Co + Mn) is 1:1OH)2@Co(OH)2@Mn(OH)2Mixing completely, placing in a tube furnace, introducing oxygen, heating to 400 ℃ at the speed of 10 ℃/min, preserving heat for 1h, heating to 820 ℃ at the same heating speed, preserving heat for 12h, cooling the tube furnace, taking out a sample, and obtaining the lithium ion battery anode material LiNiO2@LiCoO2@LiMnO2。
Example 4:
(1) firstly, 50L of reaction base solution is prepared by ammonia water and sodium hydroxide, so that the pH value of the reaction base solution is 12.0, the ammonia concentration is 0.4mol/L, the reaction base solution is heated by jacket water bath at the temperature of 60 ℃, and the reaction base solution is deoxygenated by introducing nitrogen. The method comprises the steps of simultaneously injecting a nickel-cobalt-manganese sulfate solution, ammonia water and sodium hydroxide into a 100L reaction kettle, setting the stirring speed to be 1500rpm, setting the temperature of a reaction system to be 60 ℃, the ammonia concentration to be 0.4mol/L and the pH value to be 12.0, wherein the molar ratio of nickel, cobalt and manganese in a mixed salt solution is 6:1:3, the concentration of the mixed salt solution is 2mol/L, the mass percent of the sodium hydroxide solution is 32%, the ammonia concentration of a raw material solution is 4.1mol/L, and the ammonia concentration of a supplementary solution is 0.4 mol/L.
(2) The reaction is started to be a nucleation stage, a metal salt solution, a sodium hydroxide solution and ammonia water are injected into a reaction kettle through an electric diaphragm pump, the flow rate of the metal salt solution is 3L/h, the water flow rate of raw material liquid ammonia is 0.45L/h, the flow rate of the sodium hydroxide solution is automatically adjusted through a feedback control system to control the pH value to be 12.0, the rotating speed of a stirring paddle is 1500rpm, the particle size distribution is tested once every 1 hour by using a laser particle sizer, and the nucleation stage is ended after the volume particle size distribution D50 reaches 3 microns.
(3) After the nucleation is finished, the reaction enters a first stage of nuclear growth, a metal salt solution, a sodium hydroxide solution and ammonia water are injected into a reaction kettle through an electric diaphragm pump, the flow rate of the metal salt solution is increased to 5L/h, the water flow rate of raw material liquid ammonia is increased to 0.75L/h, the pH value is controlled to be 11.5 by automatically adjusting the flow rate of the sodium hydroxide solution through a feedback control system, the rotating speed of a stirring paddle is reduced to 800rpm, the particle size distribution is tested by a laser particle sizer every 1 hour, when the particle size distribution D50 reaches 4 mu m, the feeding of the metal salt solution, the ammonia water and the sodium hydroxide solution is stopped, a liquid discharge port of the reaction kettle is opened, and 1/2 volumes ofDischarging the slurry into a concentration kettle 1, discharging clear liquid through concentration operation, pumping the concentrated slurry into a washing kettle by using a pneumatic diaphragm pump, and stirring and washing by using 2mol/L sodium hydroxide at 50 ℃ for 20min to remove SO on the surfaces of particles4 2-Discharging the residual slurry in the reaction kettle into a concentration kettle 1 for concentration operation, pumping the slurry into a concentration kettle 2 by using a pneumatic diaphragm pump after hot alkali washing in a washing kettle is finished, and pumping the slurry into the reaction kettle again after removing the redundant alkali liquor; through twice concentration, alkali washing and concentration operations, the volume of slurry in the reaction kettle is reduced, 0.4mol/L ammonia water is injected into the reaction kettle through a liquid supplementing hole, meanwhile, the pH value in the kettle is controlled to be maintained at 11.5 by a pH automatic adjusting feedback system, when the volume of the slurry in the kettle reaches 50L of the effective volume of the reaction kettle, the liquid supplementing is stopped, the feeding of a metal salt solution, a sodium hydroxide solution and the ammonia water is restarted, and the small spherical particles returned to the reaction kettle continue to grow up through coprecipitation reaction.
(4) When the volume particle size distribution D50 reaches 7 mu m, the reaction enters a second stage of nuclear growth, a metal salt solution, a sodium hydroxide solution and ammonia water are injected into the reaction kettle through an electric diaphragm pump, the flow rate of the metal salt solution is increased to 8L/h, the flow rate of the raw material liquid ammonia is increased to 1.2L/h, the flow rate of the sodium hydroxide solution is automatically adjusted through a feedback control system to control the pH value to be 11.0, the rotating speed of a stirring paddle is reduced to 500rpm to ensure that the growth speed of spherical particles is kept relatively stable, and the alkaline washing operation in the step 3 is also carried out in the process.
(5) The concentration, alkali washing and concentration operations are carried out once for every 2 mu m increase of the particle volume and particle size distribution D50.
(6) And after the particle size reaches 10 mu m, aging the slurry in the reaction kettle for 4 hours, then putting the slurry into a hot alkali washing kettle for alkali washing, then putting the slurry into a centrifuge for washing by using pure water, demagnetizing the washed material, drying and sieving to obtain the product.
(7) Weighing 120g of LiOH and 456g of Ni (OH) according to the proportion that nLi to n (Ni + Co + Mn) is 1:12@Co(OH)2@Mn(OH)2Mixing completely, placing in a tube furnace, introducing oxygen, heating to 400 deg.C at a rate of 10 deg.C/min, maintaining for 1h, heating to 820 deg.C at the same heating rate, maintaining for 12h, and standing until the temperature is reachedCooling the tube furnace, taking out the sample to obtain the positive electrode material LiNiO of the lithium ion battery2@LiCoO2@LiMnO2。
Example 5
(1) Firstly, preparing 50L of reaction base solution by using ammonia water and sodium hydroxide, enabling the pH of the prepared reaction base solution to be 11.6 and the ammonia concentration to be 0.4mol/L, heating the reaction base solution by using jacket water bath to enable the temperature to be 60 ℃, and introducing nitrogen to carry out oxygen removal treatment on the reaction base solution. The method comprises the steps of simultaneously injecting a nickel-cobalt-manganese sulfate solution, ammonia water and sodium hydroxide into a 100L reaction kettle, setting the stirring speed to be 900rpm, the reaction system temperature to be 60 ℃, the ammonia concentration in the reaction kettle to be 0.4mol/L and the pH value to be 11.6, wherein the molar ratio of nickel, cobalt and manganese in a mixed salt solution is 6:1:3, the concentration of the mixed salt solution is 2mol/L, the mass percent of a raw material sodium hydroxide solution is 32%, the ammonia concentration of a raw material solution is 4.1mol/L, and the ammonia concentration of a make-up solution is 0.4 mol/L.
(2) The reaction is started to be a nucleation stage, a metal salt solution, a sodium hydroxide solution and ammonia water are injected into a reaction kettle through an electric diaphragm pump, the flow rate of the metal salt solution is 3L/h, the water flow rate of raw material liquid ammonia is 0.45L/h, the flow rate of the sodium hydroxide solution is automatically adjusted through a feedback control system to control the pH value to be 11.6, the rotating speed of a stirring paddle is 900rpm, the particle size distribution is tested by a laser particle sizer every 1 hour, and the nucleation stage is ended after the volume particle size distribution D50 reaches 3 microns.
(3) After the nucleation is finished, the reaction enters a nuclear growth stage, a metal salt solution, a sodium hydroxide solution and ammonia water are injected into the reaction kettle through an electric diaphragm pump, the flow rate of the metal salt solution is increased to 6L/h, the flow rate of the raw material liquid ammonia is increased to 0.9L/h, the flow rate of the sodium hydroxide solution is automatically adjusted by a feedback control system to control the pH value to be maintained at 11.0, the rotating speed of a stirring paddle is reduced to 600rpm, the particle size distribution of the particles is tested once every 1 hour by using a laser particle sizer, when the particle volume and particle size distribution D50 reaches 4 μm, stopping feeding the metal salt solution, ammonia water and sodium hydroxide solution, opening the liquid outlet of the reaction kettle, discharging slurry with 1/2 volume in the kettle into the concentration kettle 1, discharging clear liquid through concentration operation, and then pumping the concentrated slurry into a washing kettle by using a pneumatic diaphragm pump, and stirring and washing the slurry for 20min by using 2mol/L sodium hydroxide at 50 ℃ to remove the particle surface.SO4 of noodle2-Discharging the residual slurry in the reaction kettle into a concentration kettle 1 for concentration operation, pumping the slurry into a concentration kettle 2 by using a pneumatic diaphragm pump after hot alkali washing in a washing kettle is finished, and pumping the slurry into the reaction kettle again after removing the redundant alkali liquor; through twice concentration, alkali washing and concentration operations, the volume of slurry in the reaction kettle is reduced, 0.4mol/L ammonia water is injected into the reaction kettle through a liquid supplementing hole, meanwhile, the pH value in the kettle is controlled to be maintained at 11.0 by a pH automatic adjusting feedback system, when the volume of the slurry in the kettle reaches 50L of the effective volume of the reaction kettle, the liquid supplementing is stopped, the feeding of a metal salt solution, a sodium hydroxide solution and the ammonia water is restarted, and the small spherical particles returned to the reaction kettle continue to grow up through coprecipitation reaction.
(4) The concentration, alkali washing and concentration operations are carried out once for every 2 mu m increase of the particle volume and particle size distribution D50.
(5) And after the particle size reaches 10 mu m, aging the slurry in the reaction kettle for 4 hours, then putting the slurry into a hot alkali washing kettle for alkali washing, then putting the slurry into a centrifuge for washing by using pure water, demagnetizing the washed material, drying and sieving to obtain the product.
(6) Weighing 120g of LiOH and 456g of Ni (OH) according to the proportion that nLi to n (Ni + Co + Mn) is 1:12@Co(OH)2@Mn(OH)2Mixing completely, placing in a tube furnace, introducing oxygen, heating to 400 ℃ at the speed of 10 ℃/min, preserving heat for 1h, heating to 820 ℃ at the same heating speed, preserving heat for 12h, cooling the tube furnace, taking out a sample, and obtaining the lithium ion battery anode material LiNiO2@LiCoO2@LiMnO2。
Comparative example 1:
the other operations were completely the same as those of example 1 except that after the clear liquid was discharged by the concentration operation in step (3), the slurry was not subjected to alkali washing.
Discharging clear liquid through concentration operation in the step (3), and pumping concentrated slurry into a reaction kettle by using a pneumatic diaphragm pump; through concentration operation, the volume of slurry in the reaction kettle is reduced, 0.4mol/L ammonia water is injected into the reaction kettle through the liquid supplementing hole, meanwhile, the pH value in the kettle is controlled to be maintained at 11.2 by the pH automatic adjusting feedback system, when the volume of the slurry in the kettle reaches 50L of the effective volume of the reaction kettle, liquid supplementing is stopped, feeding of a metal salt solution, a sodium hydroxide solution and the ammonia water is restarted, and the small spherical particles returned to the reaction kettle continue to grow up through coprecipitation reaction.
Comparative example 2:
the other operations are completely the same as those of example 1, except that after the clear liquid is discharged by the concentration operation in step (3), the slurry is not subjected to alkaline washing, and no new complexing agent solution is added after the slurry is returned to the reaction kettle.
Namely, when the particle volume and particle size distribution D50 reaches 4 μm in the step (3), slurry in the reaction kettle is injected into a concentration kettle for concentration operation, clear liquid is discharged, then the concentrated slurry is injected into the reaction kettle by using a pneumatic diaphragm pump, and the particles enter the reaction solution again for growth.
Comparative example 3:
the other operations were completely the same as those of example 1, except that the concentration, alkali wash and concentration operations were carried out every 2 μm increase in the particle volume particle size distribution D50 in the step (5) instead of the concentration, alkali wash and concentration operations every 1 μm increase.
Comparative example 4:
the other operations were completely the same as those of example 1 except that in the step (3), the hot alkali washing with 2mol/L of 50 ℃ sodium hydroxide was changed from 20 minutes to 40 minutes by using 6mol/L of 50 ℃ sodium hydroxide.
Because the concentration of the sodium hydroxide solution in the alkali washing process is too high, the alkali washing time is too long, and a product with the D50 of 10 mu m is not synthesized.
Comparative example 5:
compared with example 1, the difference is that the coprecipitation reaction is not divided into a nucleation stage and a growth stage, i.e. the coprecipitation reaction is carried out according to reaction conditions such as uniform pH value, uniform feeding speed and the like. The method comprises the following specific steps:
(1) preparing 50L of reaction base solution, wherein the pH value of the reaction base solution is 11.7, the ammonia concentration is 0.4mol/L, heating the reaction base solution in a jacket water bath to 60 ℃, and introducing nitrogen to carry out oxygen removal treatment on the reaction base solution. The method comprises the steps of simultaneously injecting a nickel-cobalt-manganese sulfate solution, ammonia water and sodium hydroxide into a 100L reaction kettle, setting the stirring speed to be 1000rpm, setting the temperature of a reaction system to be 60 ℃, setting the ammonia concentration to be 0.4mol/L and setting the pH value to be 11.7, wherein the molar ratio of nickel, cobalt and manganese in a mixed salt solution is 6:1:3, the concentration of the mixed salt solution is 2mol/L, the mass percent of a sodium hydroxide solution is 32%, the ammonia concentration of a raw material solution is 4.1mol/L, and the ammonia concentration of a supplementary solution is 0.4 mol/L.
(2) The metal salt solution, the sodium hydroxide solution and the ammonia water are injected into the reaction kettle through the electric diaphragm pump, the flow of the metal salt solution is 2L/h, the flow of the raw material liquid ammonia is 0.3L/h, and the pH value is controlled to be 11.7 by automatically adjusting the flow of the sodium hydroxide solution through the feedback control system.
(3) The reaction is started to be a nucleation stage, the pH is kept to be 11.7, the rotating speed of a stirring paddle is 1000rpm, the flow rate of the metal salt solution is 2L/h, the particle size distribution is tested once every 1 hour by using a laser particle sizer, the volume particle size distribution D50 reaches 3 mu m, the reaction enters a particle growth stage, the pH is kept at 11.7, the stirring rotating speed is kept at 1000rpm, and the feeding speed of the metal salt solution is 2L/h; when the particle volume and particle size distribution D50 reaches 4 mu m, stopping feeding of the metal salt solution, ammonia water and sodium hydroxide, opening a liquid outlet of the reaction kettle, discharging slurry with the volume of 1/2 in the kettle into a concentration kettle 1, discharging clear liquid through concentration operation, pumping the concentrated slurry into a washing kettle by using a pneumatic diaphragm pump, washing for 20min by using hot alkali to remove SO on the surfaces of the particles4 2-At the moment, the residual slurry in the reaction kettle is discharged into a concentration kettle 1 for concentration operation, the slurry is pumped into a concentration kettle 2 by using a pneumatic diaphragm pump after the hot alkali washing in a washing kettle is finished, and the slurry is pumped into the reaction kettle again after the redundant sodium hydroxide solution is removed; through twice concentration, alkali washing and concentration operations, the volume of slurry in the reaction kettle is reduced, 0.4mol/L ammonia water is injected into the reaction kettle through a liquid supplementing hole, meanwhile, the pH value in the kettle is controlled to be maintained at 11.7 by a pH automatic adjusting feedback system, when the volume of the slurry in the kettle reaches 50L of the effective volume of the reaction kettle, the liquid supplementing is stopped, the feeding of a metal salt solution, a sodium hydroxide solution and the ammonia water is restarted, and the small spherical particles returned to the reaction kettle continue to grow up through coprecipitation reaction.
(4) The concentration, alkali washing and concentration operations are carried out once for every 2 mu m increase of the particle volume and particle size distribution D50.
(5) And after the particle size reaches 10 mu m, aging the slurry in the reaction kettle for 4 hours, then putting the slurry into a hot alkali washing kettle for alkali washing, then putting the slurry into a centrifuge for washing by using pure water, demagnetizing the washed material, drying and sieving to obtain the product.
Comparative example 6:
the other operations were exactly the same as those of example 1 except that the hot alkaline washing with 2mol/L of 50 ℃ sodium hydroxide in step (3) was changed to the hot pure water washing at 50 ℃.
The S contents of the ternary precursor materials prepared in examples 1 to 2 and comparative examples 1 to 6 were measured by ICP, XRD, archimedes buoyancy method, and the results are shown in table 1. Comparative example 4 no product with a D50 of 10 μm was synthesized due to too long alkaline wash time, no relevant test was performed.
Table 1 example and comparative example precursor S impurity content grain size
Figure BDA0002801704730000191
As can be seen from the ICP test results, example 1 reduces SO in solution by displacing the solution in the autoclave4 2-Content of SO on the surface of the particles washed with hot alkali4 2-Effectively removes sulfur impurities in the precursor. From XRD, although the S impurity content of comparative example 3 is lower, the washing is too frequent, the continuity of crystal growth is damaged, the crystallinity is poor, and qualified products cannot be synthesized. This is also confirmed from the XRD pattern of fig. 2, and the peak intensity of comparative example 3 is significantly weaker than that of example 1, indicating that comparative example 3 has poor crystallinity.
The grain sizes of the precursor in the 001 direction and the 100 direction are calculated by XRD, and the thickness of the grains in the two directions is increased after the content of S impurities in the precursor is reduced, which shows that the crystallinity of the precursor can be improved and the product quality can be improved by reducing the content of S impurities.
The real density of the precursor is further detected by adopting an Archimedes buoyancy method, as shown in Table 1, the real density of the precursor prepared in the embodiment of the invention is superior to that of a comparative example, particularly the real density of the embodiment 1 is the highest, which shows that the real density of the precursor is effectively improved after the S impurity content is reduced by adopting the method disclosed by the invention, so that the compaction density of the battery is favorably improved, and the capacity of the battery is improved.
As shown in fig. 3, SEM pictures of the precursor product in comparative example 1 (right image) and comparative example 5 (left image) show that, in example 1, the process method of high reaction pH value, high stirring rotation speed, low salt solution feeding speed in the nucleation stage is adopted, reaction pH is reduced in the growth stage, stirring rotation speed is reduced, and salt feeding speed is increased, so that the dispersibility of the pellet particles in the nucleation stage is effectively enhanced, the sphericity and morphology of the product are improved, and the product quality is improved.
In order to further verify the electrochemical performance of the ternary precursor material, the ternary precursor positive electrode materials obtained in examples 1,2 and 4 and comparative example 1 are assembled into a button cell, and the assembling steps are as follows: according to the positive electrode material: weighing and mixing Super p: PVDF (polyvinylidene fluoride) in a mass ratio of 8:1:1, uniformly grinding, uniformly coating the ground mixture on an aluminum foil current collector, placing the aluminum foil current collector in a vacuum box, drying the aluminum foil current collector for 12 hours at the temperature of 80 ℃ to prepare a positive plate, cutting the positive plate into a round shape with the size of a button battery by using a punching machine, wherein the electrolyte adopts 1mol/L LiPF6The solution of (1) was prepared in a glove box, and the assembly of the coin cell was completed using a Clegard 2400 type separator as the separator and a lithium plate as the negative electrode.
Electrochemical performance test conditions: and (3) carrying out constant current charge and discharge tests on the button cell under the constant temperature condition of 25 ℃, wherein the voltage range is 2.8-4.3V, carrying out the charge and discharge performance test of the first 3 periods under the condition of 0.1C, adopting the charge and discharge multiplying power of 0.3C after the 3 rd time, and recording the charge and discharge specific capacity and the first effect after the first time and 50 cycles. Specific electrochemical performance test data are shown in table 2.
TABLE 2 electrochemical Performance data
Figure BDA0002801704730000211
As can be seen from the comparison of the electrochemical performance data of the examples 1 and 2 and the comparative example 5, the precursors synthesized in the nucleation stage and the growth stage have more compact particles, so that the compaction density of the battery pole piece is improved, and the electrochemical performance is more excellent.
In conclusion, the invention adopts the key control means of controlling the conditions of the nucleation stage and the growth stage and replenishing the new complexing agent liquid after the slurry is subjected to alkaline washing and returns to the reaction kettle, so as to obtain the ternary precursor material with low S impurity content and good crystallization property, and the lithium ion battery prepared by the anode of the ternary precursor material has better capacity and cycle performance.
While the present invention has been described in detail with reference to the preferred embodiments, it should be understood that the above description should not be taken as limiting the invention. It will be appreciated by those skilled in the art that modifications or adaptations to the invention may be made in light of the teachings of the present specification. Such modifications or adaptations are intended to be within the scope of the present invention as defined in the claims.

Claims (10)

1. A preparation method of a nickel-cobalt-manganese ternary precursor for reducing sulfur content in a continuous production process comprises the steps of taking sulfates of nickel, cobalt and manganese, alkali and a complexing agent as raw materials, synthesizing the ternary precursor to a target granularity in a reaction kettle through coprecipitation, and aging, washing, drying and sieving to obtain a ternary precursor material, and is characterized in that the synthesis of the precursor is divided into two stages:
1) a nucleation stage: forming a large amount of micro particles by adopting high pH, high stirring speed and low feeding speed;
2) and (3) growth stage: the particles grow up rapidly by adopting low pH, low stirring speed and high feeding speed;
wherein, the particle size distribution is detected every 1 hour in the growth stage, and the alkali washing operation is carried out according to the size of the volume particle size distribution D50; preferably, the alkaline washing operation comprises the following steps:
s1, stopping feeding of sulfate, alkali and a complexing agent, concentrating the slurry discharged from the reaction kettle in a concentrator 1, discharging clear liquid, increasing the solid content of the slurry, and discharging SO in the solution4 2-；
S2, washing the concentrated slurryThe kettle is used for flushing the surface of the spherical particles by hot alkali under the stirring action to remove SO on the surface of the particles4 2-Removing;
s3, pumping the washed slurry into a thickener 2 through a pump, filtering the redundant clear liquid of the slurry, pumping the filtered slurry into the reaction kettle again, and continuously growing the small spherical particles returned to the reaction kettle through coprecipitation reaction.
2. The method for preparing the nickel-cobalt-manganese ternary precursor with the reduced sulfur content in the continuous production process according to claim 1, wherein the slurry is concentrated, washed with alkali, concentrated and returned to the reaction kettle, then immediately a complexing agent with the same concentration as the reaction condition is injected into the reaction kettle, and meanwhile, the pH value of the reaction is automatically adjusted by a feedback system to maintain stable, and then the slurry is re-fed to enable the pellet particles returned to the reaction kettle to continue to grow.
3. The method for preparing the nickel-cobalt-manganese ternary precursor with the reduced sulfur content in the continuous production process according to claim 1, wherein the base in the raw material is selected from any one of NaOH or KOH, preferably NaOH; the complexing agent is selected from any one or more of ammonia water, urea, ammonium acetate, ammonium sulfate, ammonium carbonate, ammonium chloride and ammonium nitrate, and preferably ammonia water.
4. The method as claimed in claim 1, wherein the pH of the reaction kettle system in the nucleation stage is 11.5-12.0, the stirring speed is 800-1500rpm, and the feeding speed of the salt solution is 1-3L/h; and finishing the nucleation stage after the volume particle size distribution D50 of the precursor reaches 3 mu m.
5. The method as claimed in claim 1, wherein the pH of the growth stage reaction kettle system is 10.0-11.5, the stirring speed is 200-800rpm, and the feeding speed of the salt solution is 3-8L/h; after the volume particle size distribution D50 of the precursor reaches 10 mu m, ending the growth stage and beginning aging; preferably, the particle size distribution is detected every 1 hour in the growth stage, and hot alkali washing operation is carried out every 2-3 μm increase according to the particle volume particle size distribution D50 until the particles grow to the target particle size.
6. The method as claimed in claim 5, wherein the growth stage comprises a first growth stage and a second growth stage, the pH of the reaction kettle system in the first growth stage is 11.0-11.5, the stirring speed is 500-800rpm, and the feeding speed of the salt solution is 3-5L/h; starting alkali washing operation after the first stage, and ending the first growth stage after the volume particle size distribution D50 of the precursor reaches 7 mu m; preferably, after the first growth stage is finished, the reaction enters a second growth stage, the alkali washing operation is continued, the pH value of the reaction kettle system is 10.0-11.0, the stirring rotation speed is 200-500rpm, and the salt solution feeding speed is 5-8L/h; and after the volume particle size distribution D50 of the precursor reaches 10 mu m, ending the growth stage and beginning aging.
7. The method for preparing the nickel-cobalt-manganese ternary precursor with the reduced sulfur content in the continuous production process according to claim 6, wherein the hot alkali is selected from any one of sodium hydroxide, potassium hydroxide and barium hydroxide, and is preferably sodium hydroxide; the temperature of the hot alkali is 40-90 ℃, preferably 50-60 ℃; the concentration of the sodium hydroxide solution is 1-10 mol/L, preferably 2-4 mol/L.
8. The method for preparing the nickel-cobalt-manganese ternary precursor with the sulfur content reduced in the continuous production process according to claim 1, wherein the pH value of the reaction base solution is 11-13, preferably 11.2-11.9, the ammonia concentration is 0.2-0.6mol/L, preferably 0.25-0.5mol/L, and the reaction temperature is 40-70 ℃, preferably 50-60 ℃.
9. The method for preparing the nickel-cobalt-manganese ternary precursor with the reduced sulfur content in the continuous production process according to claim 1, wherein the concentration kettle is a device with a stirring function, which can discharge clear slurry liquid, leave solid phase in the kettle and increase the solid content of the slurry.
10. The method for preparing the nickel-cobalt-manganese ternary precursor with reduced sulfur content in the continuous production process according to any one of claims 1 to 9, wherein the chemical formula of the nickel-cobalt-manganese ternary precursor is NixCoyMnz(OH)2Wherein x + y + z is 1, and x is more than 0.20 and less than 0.90, y is more than 0.05 and less than 0.40, and z is more than 0.05 and less than 0.40.
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CN113321245A (en) * 2021-05-25 2021-08-31 华友新能源科技（衢州）有限公司 Nickel-cobalt-manganese hydroxide and preparation method thereof
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CN113451565A (en) * 2021-05-06 2021-09-28 福建常青新能源科技有限公司 Production process of high-tap-density high-sphericity internal radial ternary precursor
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CN115520906B (en) * 2021-06-24 2024-05-10 华友新能源科技（衢州）有限公司 Narrow-distribution large-particle nickel cobalt manganese hydroxide and preparation method thereof
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WO2024011751A1 (en) * 2022-07-14 2024-01-18 广东邦普循环科技有限公司 Preparation method for low-sulfur ternary positive electrode precursor material with high specific surface area
GB2628196A (en) * 2022-07-14 2024-09-18 Guangdong Brunp Recycling Technology Co Ltd Method for preparing ternary cathode precursor material with low sulfur content and high specific surface area
CN115490273B (en) * 2022-08-17 2023-09-22 四川顺应动力电池材料有限公司 Method for continuously preparing ternary precursor with large specific surface and prepared precursor
CN115490273A (en) * 2022-08-17 2022-12-20 四川顺应动力电池材料有限公司 Method for continuously preparing large-ratio table ternary precursor and precursor prepared by method
WO2024058481A1 (en) * 2022-09-15 2024-03-21 주식회사 엘지화학 Method for preparing cathode active material precursor
CN116081709A (en) * 2022-12-29 2023-05-09 荆门市格林美新材料有限公司 Low-sulfur low-tap-density ternary precursor small particle and preparation method thereof
CN116253369A (en) * 2023-04-25 2023-06-13 荆门市格林美新材料有限公司 Low-sulfur lithium-rich manganese-based precursor and preparation method and application thereof
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