CN117208977B

CN117208977B - Precursor of high-capacity positive electrode material, and preparation method and application thereof

Info

Publication number: CN117208977B
Application number: CN202311365237.5A
Authority: CN
Inventors: 程诚; 吴桐雨; 丁睿达; 刘庭杰; 张海艳; 胡志兵
Original assignee: Hunan Changyuan Lico Co Ltd; Jinchi Energy Materials Co Ltd
Current assignee: Hunan Changyuan Lico Co Ltd; Jinchi Energy Materials Co Ltd
Priority date: 2023-10-20
Filing date: 2023-10-20
Publication date: 2024-04-26
Anticipated expiration: 2043-10-20
Also published as: CN117208977A

Abstract

The invention belongs to the technical field of lithium ion battery materials, and discloses a precursor of a high-capacity positive electrode material, a preparation method and application thereof. In the coprecipitation method, ammonia water is not required to be continuously introduced as a complexing agent, the reaction atmosphere is not required to be a protective atmosphere, and the normal atmospheric environment is achieved by adding a proper amount of complexing agent ammonia water solution into the bottom solution of a reaction kettle, and by controlling the pH value difference between a nucleation stage and a growth stage and the flow rate difference of transition metal salt solution, the precursor has loose inner core, compact surface, specific surface area of more than or equal to 20m ²/g and tap density of more than or equal to 1.55g/cm ³. The positive electrode material obtained by mixing and sintering the precursor with lithium has higher capacity.

Description

Precursor of high-capacity positive electrode material, and preparation method and application thereof

Technical Field

The invention belongs to the technical field of lithium ion battery materials, and particularly relates to a precursor of a high-capacity positive electrode material, and a preparation method and application thereof.

Background

Under the background of global energy structure transformation and rapid development of new energy industry, lithium ion battery materials are widely applied to the fields of energy storage, electric tools, electric automobiles and the like, and compared with low-nickel materials, high-nickel materials are favored in the market due to higher energy density and lower cost advantages. The precursor with high specific surface area and high tap density can be sintered to obtain the positive electrode material with high capacity.

Patent document CN202011636978.9 provides a porous positive electrode material precursor, a preparation method thereof and a ternary positive electrode material. By selecting different surfactants at different stages of the preparation process of the precursor and controlling the pH, the core layer structure of the precursor is more compact, the shell layer structure is more loose, the specific surface area is improved, the remarkable reduction of tap density is avoided, and the multiplying power performance and the structural stability of the material are improved. The preparation method needs to add pore-forming agents (such as air or glycerol) in the reaction process, and is complex in operation.

Patent document with application number of CN202210328520.X provides a method for synthesizing a precursor of a ternary positive electrode material. The precursor synthesis process comprises three stages, wherein the first stage is a rapid nucleation stage, the second stage is an intermediate uniform growth stage, and the third stage is a slow growth stage. The morphology and performance of the precursor are controlled by adjusting the pH value, the flow of the mixed salt solution, the flow of the oxidizing gas and the rotating speed at different stages. The particle size of the precursor in the growth stage can be controlled by adjusting the pH value and the flow of the mixed salt solution; the primary particles can be refined by adjusting the flow and the rotating speed of the oxidizing gas, the aggregation phenomenon of the primary particles is improved, and the sphericity of the precursor can be improved by adjusting and controlling the concentration of low ammonia, so that the precursor with loose and porous properties and high sphericity is obtained. The prepared precursor has large specific surface area and higher tap density. But the process parameters are more adjusted and the process is relatively complex.

Disclosure of Invention

Aiming at the problems existing in the prior art, the main purpose of the invention is to provide a preparation method of a precursor of a high-capacity high-nickel cathode material, which is simple in process flow.

In order to achieve the above object, the present invention provides the following specific technical solutions.

The preparation method of the precursor of the high-nickel positive electrode material comprises the following steps:

(1) Coprecipitation reaction:

Continuously and circularly introducing a transition metal salt solution and a precipitant solution into the bottom solution of the reaction kettle to carry out coprecipitation reaction to obtain reaction slurry; the transition metal salt solution is a mixed solution of nickel salt solution, cobalt salt solution and manganese salt solution, the pH value of the reaction kettle bottom solution is 11-11.5, and the ammonia concentration is 1-5 g/L;

wherein the coprecipitation reaction comprises two stages of nucleation and growth;

controlling the pH value of the reaction system in the nucleation stage to be 11.0-11.5; the reaction duration of the nucleation stage is 2-10% of the total duration of the coprecipitation reaction;

Controlling the pH value of the reaction system in the growth stage to be 9.8-10.2; the flow rate of the transition metal salt solution in the growth stage is 3-8 times of that of the transition metal salt solution in the nucleation stage;

(2) And aging the reaction slurry after the granularity of the reaction slurry reaches the target granularity, filtering the reaction slurry, washing and drying the solid phase to obtain a precursor.

In a further preferred embodiment, the total concentration of metal ions in the transition metal salt solution is 1.5 to 2.5mol/L.

In a further preferred scheme, the precipitant solution is alkali liquor, and the concentration is 6-12 mol/L. It is further preferred that the precipitant solution is at least one selected from NaOH solution and KOH solution.

In a further preferable scheme, the volume of the bottom solution of the reaction kettle is 1/3-2/3 of the volume of the reaction kettle.

In a further preferred embodiment, the coprecipitation reaction is carried out under an unprotected atmosphere.

In a further preferred embodiment, the nucleation stage has a rotational speed of 7-9m/s.

In a further preferred embodiment, the rotational speed of the growth stage is 6-8m/s.

In a further preferred embodiment, the target particle size is 3 to 5 μm.

Based on the same inventive concept, the invention provides a precursor of the high-nickel positive electrode material prepared by the preparation method.

Further, the precursor chemical formula of the high-nickel positive electrode material is Ni _xCo_yMn_z(OH)₂, wherein x+y+z= 1,0.8 < x is less than or equal to 1, y is less than or equal to 0 and less than or equal to 0.1, and z is less than or equal to 0 and less than or equal to 0.1.

Further, the specific surface area of the precursor of the high-nickel positive electrode material is not less than 20m ²/g, and the tap density is not less than 1.55g/cm ³.

In addition, the invention provides application of the precursor of the high-nickel cathode material in preparation of the cathode material of the lithium ion battery.

The invention has the following obvious beneficial technical effects:

In the coprecipitation process, ammonia water is not required to be continuously introduced as a complexing agent, so that energy consumption is reduced.

In the coprecipitation process, the reaction atmosphere is not required to be protective, and the reaction atmosphere is normal atmospheric environment, so that the energy consumption and the cost are reduced, and the operation difficulty and the requirement on the operation process are also reduced.

The specific surface area of the precursor prepared by the method is more than or equal to 20m ²/g, the tap density is more than or equal to 1.55g/cm ³, and the precursor has high specific surface area and high tap density, and lays a good foundation for further preparing the anode material with good performance.

The coprecipitation process is simple and two-stage control, is simple and easy to operate, meets the requirements of the existing sites, equipment and the like of enterprises, does not need large-scale adjustment of equipment and production lines, and has great industrial practicability.

Drawings

Fig. 1 is an SEM image of the precursor obtained in example 1.

Fig. 2 is an SEM image of the precursor obtained in example 2.

Fig. 3 is a cross-sectional SEM image of the precursor obtained in example 2.

Fig. 4 is an SEM image of the precursor obtained in comparative example 1.

Fig. 5 is an SEM image of the precursor obtained in comparative example 2.

Detailed Description

When preparing precursors with both high specific surface area and relatively high tap density by co-precipitation, it is common in the art to continuously co-current add a transition metal salt solution, a precipitant solution and a complexing agent solution during co-precipitation. The invention develops a new method, and under the environment without protective atmosphere, the precursor with loose core, compact surface, specific surface area not less than 20m ²/g and tap density not less than 1.55g/cm ³ is realized by only adding a proper amount of complexing agent ammonia water solution into the bottom solution of the reaction kettle and controlling the pH value difference between the nucleation stage and the growth stage and the flow rate difference of the transition metal salt solution.

Specifically, the technical scheme provided by the invention is as follows:

(1) Coprecipitation reaction:

Ammonia water added into the bottom solution of the reaction kettle is continuously consumed along with the progress of coprecipitation reaction, namely, the ammonia concentration in the reaction system of the nucleation stage is higher, the ammonia concentration in the reaction system of the growth stage is lower, and the precursor meeting the requirements can be obtained by combining the control of the pH values of the nucleation stage and the growth stage.

The method provided by the invention can also be called a two-stage reaction, comprising low-flow nucleation with high pH value and high ammonia concentration and high-flow growth with low pH value and low ammonia concentration.

The ammonia concentration, the pH value and the flow rate of the transition metal salt solution are controlled to be complementary and matched with each other, so that the aim of the invention can be achieved.

In the nucleation stage, the pH value of the reaction system is controlled to be 11.0-11.5, and the ammonia concentration of the reaction system is relatively high and continuously reduced at the moment, if the pH value is too low, the nucleation amount is small, the particle agglomeration is serious, and the growth period is short; too high nucleation amount is too much, the reaction period is prolonged, new nuclei are easy to appear continuously, and materials are scrapped. And the flow rate of the transition metal salt solution is smaller, the number and the quality of the nuclei in the nucleation process are more satisfactory, and if the flow rate of the transition metal salt solution is larger, the reaction period is prolonged, so that the performance of the product is changed.

During the growth phase, the ammonia concentration of the reaction system is relatively low and continuously decreases. With the great reduction of the ammonia concentration of the reaction system, the reaction system fluctuates and new nuclei are easy to be produced. However, by controlling the pH value of the reaction system and the flow rate of the transition metal salt solution, the occurrence of new nuclei can be avoided. Controlling the pH value of the reaction system to be 9.8-10.2, wherein when the pH value is too low, the growth speed is too high, and the high specific surface area and the high tap density can not be realized; when the pH is too high, new nuclei are easy to appear continuously, so that materials are scrapped. Meanwhile, in the growth stage, the flow rate of the transition metal salt solution is improved, and the particle size growth rate can be improved by matching with the continuously reduced ammonia concentration and the relatively low pH value, and the risk of new nuclei in the growth stage is reduced. In addition, as the reaction proceeds, the ammonia concentration in the reaction system decreases, primary particles are refined, at this time, the flow rate of the transition metal salt solution increases and the lower pH value is controlled, so that an internal loose structure is further formed, and the specific surface area is increased.

In some specific embodiments, the total concentration of metal ions in the transition metal salt solution is 1.5-2.5 mol/L; the precipitant solution is alkali liquor, and the concentration is 6-12 mol/L. In the actual production process, the transition metal salt solution can be at least one of nitrate solution of transition metal and sulfate solution of transition metal, and the precipitant solution alkali liquor can be at least one of NaOH solution and KOH solution.

In some specific embodiments, the volume of the bottom solution of the reaction kettle is 1/3-2/3 of the volume of the reaction kettle.

In a specific embodiment, the reaction duration of the nucleation stage is 2-10% of the total duration of the coprecipitation reaction. When the nucleation time is too short, the initial nuclear quantity is insufficient, the reaction period is short, the sample index cannot be reached, when the reaction period is too long, the initial nuclear quantity is increased, the reaction period is prolonged, and when the initial ammonia concentration is continuously consumed, the reaction time is prolonged, so that the risk of a new nuclear of the system is extremely high. Through continuous fumbling, in the specific implementation process of the invention, the total duration of the coprecipitation reaction is controlled to be 20-55 h, and more preferably 25-45 h.

In a specific embodiment, the coprecipitation reaction of the present invention is carried out in an unprotected atmosphere.

In a specific embodiment, the nucleation stage has a rotational speed of 7-9m/s.

In a specific embodiment, the rotational speed of the growth stage is between 6 and 8m/s. Compared with the nucleation stage, the reduction of the rotation speed in the growth stage is beneficial to grain size growth, reduces equipment load, and can reduce the risk of new nuclei when the solid content is high in the later stage.

In some embodiments, the target particle size is 3-5 μm.

The invention also provides a precursor of the high-nickel positive electrode material prepared by the preparation method.

In some embodiments, the precursor chemical formula of the high nickel positive electrode material is Ni _xCo_yMn_z(OH)₂, wherein x+y+z= 1,0.8 < x.ltoreq.1, 0.ltoreq.y < 0.1, and 0.ltoreq.z < 0.1.

In some embodiments, the precursor specific surface area of the high nickel positive electrode material is not less than 20m ²/g, and tap density is not less than 1.55g/cm ³.

The preparation method of the reaction kettle bottom liquid is not particularly required, and can be prepared by adopting a method known in the art, and the reaction kettle bottom liquid is prepared by the following steps: adding water, sodium hydroxide solution and ammonia water solution into a reaction kettle; the dosages of the water, the sodium hydroxide solution and the ammonia water solution are controlled so that the pH value of the reaction kettle bottom solution is 11-11.5, the ammonia concentration is 1-5 g/L, and the volume of the reaction kettle bottom solution is 1/3-2/3 of the volume of the reaction kettle.

The method and apparatus for aging the reaction slurry and filtering the reaction slurry are not particularly limited, and may be performed by methods known in the art, and the present invention is not described in detail herein, and those skilled in the art should not understand the limitation of the present invention.

The method and apparatus for washing and drying the solid phase of the present invention are not particularly limited and may be carried out by methods known in the art, and the present invention is not described in detail herein, and those skilled in the art should not be construed as limiting the present invention.

The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments are shown, for the purpose of illustrating a further understanding of the invention, but the scope of the invention is not limited to the specific embodiments described below.

Unless defined otherwise, all technical and scientific terms used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the scope of the present invention.

Unless otherwise specifically indicated, the various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or may be prepared by existing methods.

Example 1

1) According to the mole ratio of nickel, cobalt and manganese of 0.99:0.005: and (3) preparing a sulfate mixed solution of nickel, cobalt and manganese in a proportion of 0.005, wherein the total molar concentration of metal ions in the solution is 2.0mol/L. Sodium hydroxide solution with the concentration of 10mol/L is prepared.

2) Preparing a reaction kettle base solution: adding clear water, sodium hydroxide solution and ammonia water solution into a reaction kettle to prepare base solution with the temperature of 50 ℃ and the ammonia concentration of 3.5g/L, pH and the value of 11.30, wherein the volume of the base solution is 2/3 of the volume of the reaction kettle.

3) The coprecipitation reaction is carried out, and the coprecipitation reaction is divided into two stages:

high pH nucleation stage: and (3) under the conditions of 50 ℃ and ammonia concentration of 3.5g/L and stirring linear velocity of 7m/s, the mixed solution of nickel, cobalt and manganese sulfate and the precipitant solution are added into the bottom solution of the reaction kettle in parallel flow, the flow rate of the mixed solution of nickel, cobalt and manganese sulfate is 50ml/min, the flow rate of the precipitant solution is 20ml/min, the pH value of the reaction system is controlled to be 11.3, the coprecipitation reaction is carried out, and the nucleation reaction time is 1h.

Low pH growth phase: regulating the flow of the precipitant solution, regulating the pH value of the reaction system to 10.0 and keeping the pH value at 10.0, regulating the flow of the sulfate mixed solution of nickel, cobalt and manganese to 300ml/min, regulating the stirring linear speed to 6.8m/s, reacting for 29 hours, and finishing the reaction, wherein the particle size D50 of the reaction slurry is 4 mu m.

4) Aging the reaction slurry, filtering the reaction slurry, washing, drying the solid phase, and screening to obtain the precursor.

The precursor materials were tested for specific surface area and tap density as follows:

Specific surface area: 24.54m ²/g; tap density: 1.63g/cm ³.

Fig. 1 is an SEM image of the precursor obtained in example 1. As can be seen from the figure, the precursor primary particles are extremely elongated and have many surface voids.

Example 2

1) According to the mole ratio of nickel, cobalt and manganese of 0.85:0.01: preparing a nitrate mixed solution of nickel, cobalt and manganese in a proportion of 0.05, wherein the total molar concentration of metal ions in the solution is 1.5mol/L, and preparing a sodium hydroxide solution with a concentration of 8 mol/L.

2) Preparing a reaction kettle base solution: adding clear water, sodium hydroxide solution and ammonia water solution into a reaction kettle to prepare base solution with the temperature of 40 ℃ and the ammonia concentration of 5g/L, pH and the value of 11.0, wherein the volume of the base solution is 1/3 of the volume of the reaction kettle.

High pH nucleation stage: under the conditions of 50 ℃ of temperature, 5g/L of ammonia concentration and 7m/s of linear speed, the mixed solution of nickel, cobalt and manganese nitrate and the precipitant solution are added into the bottom solution of the reaction kettle in parallel, the pH value of the reaction system is controlled to be 11.0, the flow rate of the mixed solution of nickel, cobalt and manganese nitrate is 100ml/min, the flow rate of the precipitant solution is 36ml/min, and the reaction is carried out for 40min.

Low pH growth phase: regulating the flow of the precipitant solution, regulating the pH value of the reaction system to 10.2 and keeping the pH value at 10.2, regulating the flow of the nitrate solution of nickel, cobalt and manganese to 300ml/min, controlling the pH value of the reaction system to 10.2, regulating the stirring linear speed to 6.9m/s, continuing the reaction for 20 hours, and finishing the reaction, wherein the particle size D50 of the reaction slurry is 3 mu m.

4) Aging the reaction slurry, filtering the reaction slurry, and washing, drying and screening the obtained solid phase to obtain the precursor.

Specific surface area: 21.22m ²/g. Tap density: 1.61g/cm ³.

Fig. 2 is an SEM image of the precursor obtained in example 2, and it can be seen from the figure that the primary particles are slightly coarser than in fig. 1, with more surface voids. FIG. 3 is a cross-sectional SEM of the precursor obtained in example 2, from which it can be seen that the core is porous.

Example 3

1) According to the mole ratio of nickel, cobalt and manganese of 0.9:0.05: preparing a nitrate mixed solution of nickel, cobalt and manganese in a proportion of 0.05, wherein the total molar concentration of metal ions in the solution is 2.5mol/L, and preparing a sodium hydroxide solution with the concentration of 9 mol/L.

2) Preparing a reaction kettle base solution: adding clear water, sodium hydroxide solution and ammonia water solution into a reaction kettle to prepare base solution with the temperature of 60 ℃ and the ammonia concentration of 1g/L, pH and the value of 11.5, wherein the volume of the base solution is 1/2 of the volume of the reaction kettle.

High pH nucleation stage: under the conditions of 60 ℃ of temperature, 1g/L of ammonia concentration and 7m/s of linear speed, the mixed solution of nickel, cobalt and manganese nitrate and the precipitant solution are added into the bottom solution of the reaction kettle in parallel, the pH value of the reaction system is regulated to 11.5, the flow rate of the mixed solution of nickel, cobalt and manganese nitrate is 100ml/min, the flow rate of the precipitant solution is 36ml/min, and the reaction is carried out for 1.5h.

Low pH growth phase: regulating the flow of the precipitant solution, regulating the pH value of the reaction system to 9.8 and keeping the pH value at 9.8, regulating the flow of the nitrate solution of nickel, cobalt and manganese to 800ml/min, regulating the stirring linear speed to 6.6m/s, continuing the reaction for 19 hours, and then, regulating the particle size D50 of the reaction slurry to 5 mu m, and ending the reaction.

Specific surface area: 26.35m ²/g. Tap density: 1.58g/cm ³.

Comparative example 1

The difference from example 1 is in step 3):

High pH nucleation stage: and (3) in the reaction kettle bottom solution with the ammonia concentration of 3.5g/L, pH and the value of 11.3, adding the mixed solution of nickel, cobalt and manganese sulfate, the precipitant solution and the ammonia water solution into the reaction kettle bottom solution in parallel, wherein the stirring linear speed is 7m/s, the flow rate of the mixed solution of nickel, cobalt and manganese sulfate is 50ml/min, the flow rate of the precipitant solution is 20ml/min, the pH value of the reaction system is controlled to be 11.3, the ammonia concentration is 3.5g/L, and the coprecipitation reaction is carried out for 1h.

Low pH growth phase: regulating the flow rate of the sulfate mixed solution of nickel, cobalt and manganese to 300ml/min; regulating the flow of the precipitant solution, regulating the pH value of the reaction system to 10.0 and keeping the pH value at 10.0; the ammonia concentration of the reaction system was adjusted to 3.5g/L, the stirring line speed was adjusted to 6.9m/s, and after 58 hours of reaction, the particle diameter D50 of the reaction slurry was 4. Mu.m, and the reaction was completed.

specific surface area: 7.69m ²/g. Tap density: 1.97g/cm ³.

Fig. 4 is an SEM image of the precursor obtained in comparative example 1, from which it can be seen that the primary particles are thick and have less surface voids.

Comparative example 2

The difference from example 1 is in step 3):

Low pH growth phase: the flow rate of the precipitant solution is regulated, the pH value of the reaction system is regulated to 10.0 and kept at 10.0, the flow rate of the sulfate mixed solution of nickel, cobalt and manganese is still 50ml/min, the stirring linear speed is regulated to 6.8m/s, the particle size D50 of the reaction slurry is 4.0 mu m after the reaction is carried out for 40 hours, and the reaction is finished.

specific surface area: 10.36m ²/g. Tap density: 1.7g/cm ³.

Fig. 5 is an SEM image of the precursor obtained in comparative example 2, from which it can be seen that the primary particles are thicker and have fewer surface voids.

Comparative example 3

The difference from example 1 is in step 3):

Low pH growth phase: regulating the flow rate of the sulfate mixed solution of nickel, cobalt and manganese to 300ml/min; regulating the flow of the precipitant solution, regulating the pH value of the reaction system to 10.0 and keeping the pH value at 10.0; the ammonia concentration of the reaction system is controlled to be 1.5g/L, the stirring linear speed is regulated to be 6.8m/s, the particle size D50 of the reaction slurry is 4.0 mu m after the reaction is carried out for 35 hours, and the reaction is finished.

Specific surface area: 14.48m ²/g. Tap density: 1.74g/cm ³.

Specific surface area and tap density pairs of the precursors prepared in examples 1 to 3 and comparative examples 1 to 3 are shown in table 1.

TABLE 1

The precursor lithium mixture prepared in examples 1-3 and comparative examples 1-3 was sintered to obtain a positive electrode material, and the specific process was as follows: according to the mole ratio of Li to Me (the sum of Ni, co and Mn atoms) element of 1.03:

1. Carrying out high-speed ball milling and mixing on the precursor and LiOH; placing the uniformly mixed materials in a muffle furnace filled with oxygen for sintering; heating to 700 ℃ at a heating rate of 5 ℃/min, sintering at a constant temperature of 10h, and cooling with a furnace; and crushing and dissociating the cooled material by using a pair roller and an air flow mill, and sieving the crushed and dissociated material with a 325-mesh sieve to obtain a sample.

The positive electrode material obtained by testing has the effect on the performance of the battery, and the specific testing means are as follows:

(1) Preparation of positive plate

The prepared positive electrode material, a conductive agent SuperP and a binder polyvinylidene fluoride (PVDF) are mixed according to the mass ratio of 90:5:5 and N-methyl pyrrolidone (NMP) are mixed and stirred uniformly to prepare positive electrode slurry (the solid content is about 40%), the positive electrode slurry is coated on a current collector aluminum foil, the positive electrode slurry is dried at 105 ℃, rolled at room temperature until the surface density is 2.8-3.3 g/cm ³, punched and sheared into wafers with phi 14mm, and then the positive electrode plate is prepared.

(2) Assembly of lithium ion batteries

The button cell was assembled in a glove box. The electrolyte was assembled in the order of "negative electrode case-nickel foam sheet-8 drops of electrolyte-separator-8 drops of electrolyte-positive electrode sheet-positive electrode case", wherein the electrolyte consisted of Ethylene Carbonate (EC), ethylmethyl carbonate (EMC) and dimethyl carbonate (DMC) (EC: EMC: DMC volume ratio=1:1:1), containing LiPF ₆ of 1.0M.

Wherein, the diameter of the positive plate is 14mm, the diameter of the lithium plate is 18mm, the diameter of the diaphragm is 22mm, and the size of the battery cases (positive electrode case and negative electrode case) is 24mm. The separator was a 16 μm thick separator. The assembled button cell was put in a mold cavity of a hydraulic sealer (purchased from Shenzhen Kogyo Zhida technology Co., ltd.) and locked, pressurized with >450kg/cm ², and then unlocked, and the sealed button cell was taken out.

Performance test of button cell:

And detecting the charge-discharge cycle characteristics of the button cell by using a blue electric test cabinet at 25 ℃, charging and discharging in a voltage interval of 2.8V-4.3V at a charge-discharge rate of 0.1C, specifically, charging to 4.3V at a constant current of 0.1C, charging to a cut-off current of 0.02C at a constant voltage of 4.3V, standing for 5min, discharging to 2.8V at a constant voltage of 0.1C, standing for 5min, and recording the charge-discharge capacity after the first cycle.

The results are shown in Table 2.

TABLE 2

As can be seen from table 2, the positive electrode material obtained by the technical scheme provided by the invention has better capacity performance.

The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.

Claims

1. The preparation method of the precursor of the high-nickel positive electrode material is characterized by comprising the following steps of:

(1) Coprecipitation reaction:

Continuously and circularly introducing a transition metal salt solution and a precipitator solution into the bottom solution of the reaction kettle, and performing coprecipitation reaction without introducing a complexing agent solution to obtain reaction slurry; the transition metal salt solution is a mixed solution of nickel salt solution, cobalt salt solution and manganese salt solution, the pH value of the reaction kettle bottom solution is 11-11.5, and the ammonia concentration is 1-5 g/L;

Wherein the coprecipitation reaction is carried out under an unprotected atmosphere, and comprises two stages of nucleation and growth;

2. The method according to claim 1, wherein the total concentration of transition metal ions in the transition metal salt solution is 1.5 to 2.5mol/L.

3. The preparation method of claim 1 or 2, wherein the precipitant solution is alkali liquor with a concentration of 6-12 mol/L.

4. The method according to claim 3, wherein the precipitant solution is at least one selected from a NaOH solution and a KOH solution.

5. The preparation method according to claim 1 or 2, wherein the volume of the reaction kettle bottom liquid is 1/3-2/3 of the volume of the reaction kettle.

6. The process according to claim 1, wherein the nucleation stage has a stirring line speed of 7-9m/s.

7. The method of claim 1 or 6, wherein the stirrer line speed in the growth stage is 6-8m/s.

8. The method of claim 1, wherein the target particle size is 3-5 μm.