CN110589903A - A kind of large particle nickel cobalt manganese hydroxide and preparation method thereof - Google Patents

Abstract

A method for preparing large-grain nickel-cobalt-manganese hydroxides, comprising: 1. Adding pure water and a complexing agent to the reaction system as a base liquid and continuously feeding nitrogen gas at a temperature of 40-60°C, starting stirring and adding nickel Cobalt manganese salt solution, alkali solution and ammonia water, control the pH of the reaction solution at 11.0~12.0; 2. Stop the reaction when the reaction particle size reaches 12.0μm, add alkali solution to adjust pH ≥ 13.0, then add bicarbonate solution and age for 2~ 4 hours; 3. After aging, continue to add nickel-cobalt-manganese salt solution, alkali solution and ammonia water, control the pH of the reaction solution at 11.0~12.0, and stop the reaction when the particle size in the reaction system grows to the target particle size. The method of the invention can prepare the nickel-cobalt-manganese hydroxide with particle size D50 ≥ 18.0 μm, high sphericity and no cracks, has simple production process and high production capacity, and is suitable for large-scale industrial production.

Description

A kind of large particle nickel cobalt manganese hydroxide and preparation method thereof

technical field

The invention relates to the technical field of lithium ion batteries, in particular to a large particle nickel-cobalt-manganese hydroxide and a preparation method thereof.

Background technique

With the development of the new energy industry, lithium-ion batteries have attracted much attention as a new generation of green energy. Among them, as one of the key core technologies of lithium-ion batteries, cathode materials account for one-third of the production cost of lithium-ion batteries, and their performance directly affects the capacity, cycle and safety performance of lithium-ion batteries.

At present, the lithium-ion battery materials that have been successfully commercialized mainly include lithium cobaltate, lithium iron phosphate and nickel-cobalt-manganese ternary cathode materials. Among them, lithium cobaltate is the earliest positive electrode material successfully commercialized, and its compacted density of the electrode sheet is the highest among all positive electrode materials, which can reach 4.0g/cm ³ . Therefore, in the pursuit of light and thin 3C market, lithium cobalt oxide material still occupies a dominant position, but the high cost and toxicity of lithium cobalt oxide require more suitable materials to replace it.

The nickel-cobalt-manganese ternary material combines the synergistic effect of the three elements of nickel, cobalt and manganese. The substitution of nickel and manganese for part of cobalt makes the material have the advantages of higher capacity, low cost and excellent cycle performance, and gradually replaces lithium cobalt oxide in various applications. Material. However, the compacted density of the conventional ternary cathode material is only 3.5g/cm ³ , so the replacement of lithium cobaltate by the ternary cathode material will sacrifice the volume energy density of the material, thus further improving the volume energy density of the ternary lithium-ion battery It has high application value.

The mixing of large and small particles under different gradations can effectively increase the compaction density of the ternary cathode material, and find the optimal size particle blending combination to prepare the pole piece of the ternary cathode material, and the compaction density can reach 3.8~3.9g /cm ³ , which is close to the compacted density of lithium cobalt oxide. The particle size requirement of this process for large particles is D50>18.0μm. However, when the ternary precursor is prepared by co-precipitation, when the reaction particle size in the system grows to 12.0μm (deleted), the amount of material in the reaction system increases, and the stirring Under the action of shear force and inter-particle collision, the particles become smoother, and the newly generated crystal nuclei are difficult to attach to the surface of large particles for growth, so the growth rate of the particle size in the system slows down, making it difficult for the particle size to grow to more than 18.0 μm. The shear of stirring and the collision between particles can easily cause large particles to crack easily. Therefore, how to effectively increase the growth rate of large-particle precursors and maintain particle integrity, so as to realize the simplification of the production process and high productivity has become an urgent problem to be solved.

Chinese patent CN201611266605 discloses a method for preparing a large-particle precursor for lithium-ion battery positive electrode materials. First, the mixed metal salt solution, precipitant and complexing agent are added to the reactor 1 for continuous reaction 1, and the overflow liquid enters In the reaction system 2, the mixed metal salt solution, the precipitating agent and the complexing agent flow into the reactor 2 at the same time to carry out the continuous reaction 2. The patent prepares precursors with large particle size and narrow particle size distribution. The series connection between reactors requires high air tightness of reaction equipment and pipelines, and the process of continuously changing materials is relatively cumbersome.

Chinese patent CN20170407336 discloses a preparation method of a nickel-rich precursor material that can prevent particle breakage. The reaction slurry is prepared and the target particle size D50=d of the precursor is set; during the preparation reaction process, the reactants generated by monitoring The real-time particle size D50 is denoted as d1; when the measured d1 value is significantly smaller than the d value, the particle size distribution Span value of the reactant is lowered by changing the process conditions, and when the measured d1 value is subsequently detected to be near d, change again The process conditions increase the Span value of the particle size distribution of the generated reactant to control the Span value within a certain range; while maintaining the Span value within the control range, continue the subsequent preparation reaction until the particle size of the produced reactant grows to a large d value. The precursor material prepared by this patent has high sphericity and complete particles, but the particle size distribution is wide and the D50 is relatively small.

Therefore, how to solve the above-mentioned deficiencies in the prior art becomes the subject to be studied and solved by the present invention.

Contents of the invention

The object of the present invention is to provide a large particle nickel cobalt manganese hydroxide and a preparation method thereof.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A large particle nickel-cobalt-manganese hydroxide, the general formula of the nickel-cobalt-manganese hydroxide is Ni _x Co _y Mn _z (OH) ₂ , wherein 0.4≤x<1.0, x+y+z=1; The average particle size of the nickel-cobalt-manganese hydroxide is ≥18 μm, the particle size distribution Span value is ≤0.70, and the TD is ≥2.0 g/cm ³ .

The relevant content in the above-mentioned technical scheme is explained as follows:

1. In the above scheme, the value of the Span is the radial distance, indicating the particle size distribution distance; the TD is the tap density.

In order to achieve the above object, another technical solution adopted by the present invention is:

A preparation method of large particle nickel cobalt manganese hydroxide; comprising the following steps:

Step 1. Add pure water and complexing agent to the reaction system as the bottom liquid and continue to feed nitrogen gas. The reaction temperature is controlled at 40~60°C. Then start stirring and add nickel-cobalt-manganese salt solution and alkali solution to the reaction system and ammonia water, adding alkali solution to control the pH of the reaction solution at 11.0~12.0;

Step 2. When the reaction particle size in step 1 reaches 12.0 μm, suspend the reaction, add alkali solution to the reaction system to adjust the pH, control the pH of the reaction system ≥ 13.0, add bicarbonate solution and age for 2~ 4 hours;

Step 3. After the aging in step 2 is completed, continue to add nickel-cobalt-manganese salt solution, alkali solution and ammonia water to the reaction system, and add alkali solution to control the pH of the reaction solution at 11.0~12.0. When the particle size in the reaction system grows to The target particle size ends the reaction.

The relevant content in the above-mentioned technical scheme is explained as follows:

1. In the above scheme, the nickel-cobalt-manganese salt solution in step 1 and step 3 is at least one of sulfate, nitrate and chloride salt of nickel-cobalt-manganese, and its salt solution concentration is 2 ~ 4mol/L;

The concentration of the alkali solution in step 1 and step 3 is 20-50%, and the concentration of ammonia water is 2-5mol/L.

2. In the above scheme, the bicarbonate solution in step 2 is at least one of ammonium bicarbonate, potassium bicarbonate, sodium bicarbonate, calcium bicarbonate and magnesium bicarbonate, wherein the concentration of the bicarbonate solution is 1 ~ 4mol/ L, and the input amount is 1~5% of the mass percentage of the material in the reaction system.

3. In the above scheme, the general formula of the nickel-cobalt-manganese hydroxide prepared in step three is Ni _x Co _y Mn _z (OH) ₂ , where 0.4≤x<1.0, x+y+z=1; the nickel-cobalt-manganese-hydrogen The average particle size of the oxide is ≥18.0 μm, the particle size distribution Span value is ≤0.70, and the TD is ≥2.0 g/cm ³ .

Working principle of the present invention and advantage are as follows:

The invention provides a large-particle nickel-cobalt-manganese hydroxide and a preparation method thereof. The method can prepare nickel-cobalt-manganese hydroxide with a particle size D50 ≥ 18.0 μm, high sphericity and no cracks. The production process of the preparation method is simple and convenient. High production capacity, suitable for large-scale industrial production.

Compared with the prior art, the preparation method of the present invention has the following characteristics:

1. The present invention uses a specific amount of bicarbonate to react in an alkaline solution in the slow stage of particle size growth, releasing a small amount of _CO to make the surface of the particles change from smooth to loose, increasing the specific surface area of the particles, and producing crystal nuclei The uneven surface required for growth is conducive to the better attachment of newly generated crystal nuclei to the particle surface for growth;

2. In the co-precipitation reaction, as the amount of product in the system increases, the growth rate of the particles will also slow down, and it is necessary to transfer a part of the material out through more reaction vessels or reduce the rotation speed to make the particles agglomerate; The invention does not require additional use of a new reaction vessel or transfer of materials, the production process is simple, and the production capacity is high; at the same time, the rotation speed is kept constant, and as the reaction time progresses, there is no agglomeration between particles, and the degree of sphericity is high.

Description of drawings

Accompanying drawing 1 is the SEM photo that the embodiment of the present invention prepares nickel-cobalt-manganese hydroxide D50 to reach 12.0 μ m;

Accompanying drawing 2 is the particle size distribution curve figure that the embodiment of the present invention prepares nickel-cobalt-manganese hydroxide D50 to reach 12.0 μm;

Accompanying drawing 3 is the SEM photograph after adding bicarbonate after the nickel-cobalt-manganese hydroxide D50 reaches 12.0 μm prepared by the embodiment of the present invention;

Accompanying drawing 4 is the particle size distribution curve after adding bicarbonate after the nickel-cobalt-manganese hydroxide D50 of the embodiment of the present invention reaches 12.0 μm;

Accompanying drawing 5 is the SEM photo of the nickel-cobalt-manganese hydroxide D50 prepared by the embodiment of the present invention after reaching 19.5 μm;

Accompanying drawing 6 is the particle size distribution curve of the nickel-cobalt-manganese hydroxide prepared in the embodiment of the present invention after the D50 reaches 19.5 μm.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing and embodiment:

Embodiment: The following will clearly illustrate this case with drawings and detailed descriptions. After any person skilled in the art understands the embodiment of this case, he can change and modify it by the technology taught in this case without departing from the spirit of this case. with range.

The terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting of the present case. Singular forms such as "a", "the", "the", "this" and "the", as used herein, also include plural forms.

As used herein, "comprising", "comprising", "having" and the like are all open terms, meaning including but not limited to.

Regarding the terms used in this article, unless otherwise specified, generally have the ordinary meaning of each term used in this field, in the content of this case and in the special content. Certain terms used to describe the subject matter are discussed below or elsewhere in this specification to provide those skilled in the art with additional guidance in describing the subject matter.

Referring to accompanying drawings 1 to 6, a large particle nickel-cobalt-manganese hydroxide, the general formula of the nickel-cobalt-manganese hydroxide is Ni _x Co _y Mn _z (OH) ₂ , where 0.4≤x<1.0, x +y+z=1; the average particle size (D50) of the nickel-cobalt-manganese hydroxide is ≥18 μm, the particle size distribution span value is ≤0.70, and the TD is ≥2.0 g/cm ³ .

The preparation method of described large particle nickel cobalt manganese hydroxide comprises the following steps:

Step 1. Add pure water and complexing agent to the reaction system as the bottom liquid and continue to feed nitrogen gas. The reaction temperature is controlled at 40~60°C. Then start stirring and pump nickel-cobalt-manganese salt into the reaction system through a metering pump. Solution, alkali solution and ammonia water, add alkali solution to control the pH of the reaction solution at 11.0~12.0;

Step 2. When the reaction particle size in step 1 reaches 12.0 μm, suspend the reaction, add alkali solution to the reaction system to adjust the pH, and control the pH of the reaction system to ≥ 13.0. The effect is to increase the concentration of ^OH- ions in the solution and inhibit HCO ^3- The ions are hydrolyzed to form a small amount of H ₂ CO ₃ to avoid the hydrolysis reaction of nickel-cobalt-manganese hydroxide; after the pH adjustment, add bicarbonate solution and age for 2-4 hours;

Step 3. After the aging in step 2 is completed, continue to pump nickel-cobalt-manganese salt solution, alkali solution and ammonia water into the reaction system through a metering pump, and add alkali solution to control the pH of the reaction solution at 11.0~12.0. This condition compares It is suitable for the growth of large particle products. If the pH is too low, the precipitation of nickel, cobalt and manganese metal ions is not complete. If the pH is too high, the crystal growth rate is too slow, which is not conducive to the growth of large particle products; when the particle size in the reaction system grows to the target particle size (D50≥18.0μm ) to end the reaction.

Wherein, the nickel-cobalt-manganese salt solution in step 1 and step 3 is at least one of sulfate, nitrate and chloride salt of nickel-cobalt-manganese, and its salt solution concentration is 2 ~ 4mol/L;

The concentration of the alkali solution in step 1 and step 3 is 20-50%, and the concentration of ammonia water is 2-5mol/L.

Wherein, the bicarbonate solution in step 2 is at least one of ammonium bicarbonate, potassium bicarbonate, sodium bicarbonate, calcium bicarbonate and magnesium bicarbonate, wherein the concentration of the bicarbonate solution is 1 ~ 4mol/L, And the input amount is 1-5% of the mass percentage of the material in the reaction system.

Wherein, the general formula of nickel-cobalt-manganese hydroxide prepared in step three is Ni _x Co _{y Mnz} (OH) ₂ , where 0.4≤x<1.0, and x+y+z=1; D50≥18.0 μm, particle size distribution Radial distance Span value ≤ 0.70.

The preparation method of large particle nickel-cobalt-manganese hydroxide of the present invention can carry out with reference to following steps during concrete experiment:

Step (1), add 2500L of pure water to the reaction system of 10m³, and then start adding the 2mol/L nickel-cobalt-manganese mixed flow rate salt solution and 3mol/L ammonia solution respectively through the metering pump in parallel flow mode, wherein The molar coefficient ratio of metal nickel, cobalt and manganese in raw materials is 60:20:20; at the same time, 4mol/L sodium hydroxide solution is supplied to control the pH value of the process to be 11.5±0.1; nitrogen (or other inert gas) protection is introduced during the feeding process, And control the ammonia concentration in the reaction solution at 1.0±0.2mol/L, the stirring speed at 150 rpm and the reaction system temperature at 50±4°C.

Step (2), real-time monitoring of particle size changes during the reaction process, when the particle size grows to 12.0 μm, stop the reaction, add alkali solution to make the pH of the reaction system 13.0, and then put 2mol/L ammonium bicarbonate solution into the reaction system 300L for aging for 4 hours.

Step (3), after the aging is completed, the 2mol/L nickel-cobalt-manganese mixed flow rate salt solution and the 3mol/L ammonia solution are respectively started to add liquid through the metering pump at an equal speed and concurrent flow, and at the same time supply 4mol/L sodium hydroxide solution Control the pH value of the process to 11.5±0.1 to continue the reaction until the particle size grows to the target particle size D50>18.0 μm to end the reaction.

Step (4), age the product obtained in step (3) for 2 hours, and centrifuge and wash until the material is neutral, and finally dry it completely at 150°C to obtain the final sample, which is the nickel-cobalt-manganese ternary precursor Ni _0.6 Co _0.2 Mn _0.2 (OH) ₂ .

Combining Figure 1 and Figure 2, it can be seen that after the reaction particle size grows to 12.0 μm, the surface of the particle is smooth, and after aging in the ammonium bicarbonate solution, the surface roughness of the particle increases, and the sphericity does not decrease. At the same time, it can be seen from Figure 3 and Figure 4 that after the ammonium bicarbonate solution is aged, the particle size in the system does not change.

It can be seen from Figure 5 that after the reaction, the surface of the product is smooth, the particles have a high degree of sphericity, and there is no cracking. Combining with Figure 6, it can be seen that the particle size distribution of the product is narrow and the particle size uniformity is high.

The above-mentioned embodiments are only to illustrate the technical concept and characteristics of the present invention, and the purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and not to limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention shall fall within the protection scope of the present invention.

Claims (5)

1. A large-particle nickel cobalt manganese hydroxide is characterized in that: the general formula of the nickel-cobalt-manganese hydroxide is Ni_xCo_yMn_z(OH)₂Wherein x is more than or equal to 0.4 and less than 1.0, and x + y + z = 1; the average particle size of the nickel-cobalt-manganese hydroxide is more than or equal to 18 mu m, the particle size distribution Span value is less than or equal to 0.70, and the TD is more than or equal to 2.0g/cm³。

2. A preparation method of large-particle nickel-cobalt-manganese hydroxide; the method is characterized in that:

the method comprises the following steps:

step one, adding pure water and a complexing agent into a reaction system to serve as a base solution, continuously introducing nitrogen, controlling the reaction temperature to be 40 ~ 60 ℃, then starting stirring, adding a nickel-cobalt-manganese salt solution, an alkali solution and ammonia water into the reaction system, and adding the alkali solution to control the pH of the reaction solution to be 11.0 ~ 12.0.0;

step two, when the reaction granularity in the step one reaches 12.0 mu m, stopping the reaction, adding an alkali solution into the reaction system to adjust the pH value, controlling the pH value of the reaction system to be more than or equal to 13.0, and adding a bicarbonate solution and aging for 2 ~ 4 hours after the pH value is adjusted;

and step three, after the aging of the step two is finished, continuously adding the salt solution of nickel, cobalt and manganese, the alkali solution and ammonia water into the reaction system, adding the alkali solution to control the pH value of the reaction solution to be 11.0 ~ 12.0.0, and finishing the reaction when the granularity in the reaction system grows to the target granularity.

3. The method according to claim 2, wherein the nickel cobalt manganese salt solution in the first step and the third step is at least one of sulfate, nitrate and chloride of nickel cobalt manganese, and the concentration of the salt solution is 2 ~ 4 mol/L;

the concentration of the alkali solution in the first step and the third step is 20 ~ 50%, and the concentration of the ammonia water is 2 ~ 5 mol/L.

4. The preparation method according to claim 2, wherein the bicarbonate solution in the second step is at least one of ammonium bicarbonate, potassium bicarbonate, sodium bicarbonate, calcium bicarbonate and magnesium bicarbonate, wherein the concentration of the bicarbonate solution is 1 ~ 4mol/L, and the input amount is 1 ~ 5% of the mass percentage of the materials in the reaction system.

5. The method of claim 2, wherein: the general formula of the nickel-cobalt-manganese hydroxide prepared in the third step is Ni_xCo_yMn_z (OH)₂Wherein x is more than or equal to 0.4 and less than 1.0, and x + y + z = 1; the average particle size of the nickel-cobalt-manganese hydroxide is more than or equal to 18.0 mu m, the particle size distribution Span value is less than or equal to 0.70, and the TD is more than or equal to 2.0g/cm 3.