阅读说明：本技术 一种新型小颗粒三元前驱体及其制备方法 (Novel small-particle ternary precursor and preparation method thereof ) 是由 朱用 袁超群 褚凤辉 王梁梁 李加闯 贺建军 于 2021-08-24 设计创作，主要内容包括：一种新型小颗粒三元前驱体及其制备方法,三元前驱体为Ni-(x)Co-(y)Mn-(z)(OH)-(2),0.50≤x＜0.98,0＜y＜0.50,0.01＜z＜0.50,且x+y+z=1。制备方法包括：一、配制Ni、Co、Mn金属液；配制氢氧化钠或氢氧化钾溶液作为沉淀剂；配制氨水溶液作为络合剂；二、向合成釜中加入氧化铝颗粒作为晶种,加入沉淀剂、纯水和络合剂配成底液,控制底液pH值为11.00～11.60,温度40～60℃；底液中的氧化铝颗粒为0.2～1.2g/L；三、将金属液、沉淀剂及络合剂分别以200～800 mL/min的流速持续加入到合成釜中进行共沉淀,生长到目标粒度时停止进液；然后调节温度到70～80℃,控制pH保持12.50～13.50进行陈化,陈化3～4h获得共沉淀产物；四、将共沉淀产物经过压滤、洗涤、干燥得到产品。本发明通过制备出内部中空的三元正极材料能够缓解充放电产生的体积膨胀,从而提高电化学性能。(Novel small-particle ternary precursor and preparation method thereof, wherein the ternary precursor is Ni x Co y Mn z (OH) 2 X is more than or equal to 0.50 and less than 0.98, y is more than 0 and less than 0.50, z is more than 0.01 and less than 0.50, and x + y + z = 1. The preparation method comprises the following steps: firstly, preparing Ni, Co and Mn metal liquid; preparing sodium hydroxide or potassium hydroxide solution as a precipitator; preparing an ammonia water solution as a complexing agent; secondly, adding alumina particles serving as seed crystals into the synthesis kettle, adding a precipitator, pure water and a complexing agent to prepare a base solution, and controlling the pH value of the base solution to be 11.00-11.60 and the temperature to be 40-60 ℃; the alumina particles in the base solution are 0.2-1.2 g/L; thirdly, continuously adding the metal liquid, the precipitator and the complexing agent into the synthesis kettle at the flow rate of 200-800 mL/min respectively for coprecipitation, and stopping liquid feeding when the metal liquid grows to the target granularity; then adjusting the temperature to 70-80 ℃, controlling the pH value to be kept at 12.50-13.50, aging, and aging for 3-4 h to obtain a coprecipitation product; and fourthly, carrying out filter pressing, washing and drying on the coprecipitation product to obtain the product. The invention can relieve charge and discharge by preparing the ternary cathode material with hollow interiorThe resulting volume expands, thereby improving electrochemical performance.)

1. A novel small-particle ternary precursor is characterized in that: has a chemical formula of Ni_xCo_yMn_z(OH)₂Wherein x is more than or equal to 0.50 and less than 0.98, y is more than 0 and less than 0.50, z is more than 0.01 and less than 0.50, and x + y + z = 1.

2. The ternary precursor according to claim 1, wherein: d50 is 3-5 um, and the tap density is 1.45 to1.95g/cm³The specific surface area is 10-25 m²/g。

3. A preparation method of a novel small-particle ternary precursor is characterized by comprising the following steps: for preparing the ternary precursor of claim 1;

the preparation method comprises the following steps:

preparing Ni, Co and Mn metal liquid;

preparing sodium hydroxide or potassium hydroxide solution as a precipitator;

preparing an ammonia water solution as a complexing agent;

adding alumina particles serving as seed crystals into a closed synthesis kettle, adding the precipitant, pure water and the complexing agent to prepare a base solution, controlling the pH value of the base solution to be 11.00-11.60 by using the precipitant, and maintaining the temperature to be 40-60 ℃; the alumina particles in the base solution are 0.2-1.2 g/L;

step three, keeping the stirring of the synthesis kettle open, continuously adding the metal liquid, the precipitator and the complexing agent in the step one into the synthesis kettle at the flow rate of 200-800 mL/min respectively for coprecipitation reaction, and stopping feeding liquid when the metal liquid grows to the target granularity;

then, adjusting the temperature of the synthesis kettle to 70-80 ℃, controlling the pH value by the precipitator to keep 12.50-13.50, aging, and aging for 3-4 hours to obtain a coprecipitation product;

and step four, carrying out filter pressing, washing and drying on the coprecipitation product in the step three to obtain a ternary precursor with a hollow interior.

4. The production method according to claim 3, characterized in that: in the first step, the total molar concentration of Ni, Co and Mn is 1.5-2.5 mol/L.

5. The production method according to claim 3, characterized in that: in the second step, the particle size of the alumina particles is 0.6-1.2 um.

6. The production method according to claim 3, characterized in that: in the second step, the ammonia concentration of the base solution is 0.10-0.40 mol/L.

7. The production method according to claim 3, characterized in that: and in the third step, the pH value in the reaction process is kept at 11.00-11.60, the reaction temperature is kept at 40-60 ℃, and the rotating speed of the synthesis kettle is 500-700 r/min.

Technical Field

The invention relates to the technical field of lithium ion battery anode materials, in particular to a novel small-particle ternary precursor and a preparation method thereof.

Background

The rapid development of new energy automobiles drives the rapid increase of the demand of the anode materials of lithium ion batteries, particularly power type anode materials. Among the cathode materials, the ternary material is the first choice material for lithium battery, especially the power type ternary cathode material, because of its low price and stable performance.

Although the ternary cathode material has many advantages, some defects still remain to be solved. For example, the ternary positive electrode material is prone to generate large volume change in the charging and discharging process, and primary particles in the material are crushed and dissolved, so that the capacity is rapidly attenuated, especially under the condition of large-current charging and discharging. In order to improve the electrochemical performance of the ternary cathode material, the prepared ternary precursor with a hollow interior can effectively relieve the volume change in the charging and discharging process, increase the contact area with the electrolyte, improve the transmission efficiency of lithium ions and improve the rate capability.

Therefore, how to prepare a ternary precursor having a hollow interior to effectively solve the above problems has been the subject of the present invention.

Disclosure of Invention

The invention aims to provide a novel small-particle ternary precursor and a preparation method thereof.

In order to achieve the purpose, the technical scheme adopted by the invention on the product level is as follows:

a novel small-particle ternary precursor with chemical formula of Ni_xCo_yMn_z(OH)₂Wherein x is more than or equal to 0.50 and less than 0.980 < y < 0.50, 0.01 < z < 0.50, and x + y + z = 1.

The relevant content in the above technical solution is explained as follows:

1. in the scheme, D50 is 3-5 um, and the tap density is 1.45-1.95 g/cm³The specific surface area is 10-25 m²/g。

In order to achieve the purpose, the technical scheme adopted by the invention in the aspect of the method is as follows:

a preparation method of a novel small-particle ternary precursor comprises the following steps:

preparing Ni, Co and Mn metal liquid;

preparing sodium hydroxide or potassium hydroxide solution as a precipitator;

preparing an ammonia water solution as a complexing agent;

adding alumina particles serving as seed crystals into a closed synthesis kettle, adding the precipitant, pure water and the complexing agent to prepare a base solution, controlling the pH value of the base solution to be 11.00-11.60 by using the precipitant, and maintaining the temperature to be 40-60 ℃; the alumina particles in the base solution are 0.2-1.2 g/L;

step three, keeping the stirring of the synthesis kettle open, continuously adding the metal liquid, the precipitator and the complexing agent in the step one into the synthesis kettle at the flow rate of 200-800 mL/min respectively for coprecipitation reaction, and stopping feeding liquid when the metal liquid grows to the target granularity;

then, adjusting the temperature of the synthesis kettle to 70-80 ℃, controlling the pH value by the precipitator to keep 12.50-13.50, aging, and aging for 3-4 hours to obtain a coprecipitation product;

and step four, carrying out filter pressing, washing and drying on the coprecipitation product in the step three to obtain a ternary precursor with a hollow interior.

The relevant content in the above technical solution is explained as follows:

1. in the scheme, in the step one, the total molar concentration of Ni, Co and Mn is 1.5-2.5 mol/L.

2. In the scheme, in the step one, the precipitant can be sodium hydroxide or potassium hydroxide solution with the mass fraction of 20-40%.

3. In the scheme, in the first step, the complexing agent can be an ammonia water solution with the mass fraction of 2-6%.

4. In the above scheme, in the second step, the particle size of the alumina particles is 0.6-1.2 um.

5. In the scheme, in the second step, the ammonia concentration of the base solution is 0.10-0.40 mol/L.

6. In the scheme, the pH value in the reaction process in the third step is kept at 11.00-11.60, the reaction temperature is kept at 40-60 ℃, and the rotating speed of the synthesis kettle is 500-700 r/min.

7. In the scheme, in the third step, the target particle size D50 is 3-5 um.

The working principle and the advantages of the invention are as follows:

1. the invention prepares the ternary precursor with the core-shell structure by taking alumina particles as seed crystals and adopting a coprecipitation method. The temperature of the synthesis kettle is kept at 70-80 ℃, the pH value is adjusted to 12.50-13.50, the alumina in the ternary precursor can be quickly dissolved to form an internal hollow structure, and aging is carried out for 3-4 h so as to completely dissolve the alumina in the ternary precursor. The ternary cathode material with the hollow interior can increase the contact area with electrolyte, improve the lithium ion transmission efficiency and improve the multiplying power performance.

2. According to the invention, the reaction process conditions of the coprecipitation stage can be adopted to obtain the material with the D50 of 3-5 um and the tap density of 1.45-1.95 g/cm³The specific surface area is 10-25 m²A ternary precursor with a hollow interior.

3. The preparation method has the advantages of reliable process, simplicity, easy operation and easy industrial production.

In conclusion, the ternary cathode material with a hollow interior can relieve volume expansion generated by charge and discharge, so that the electrochemical performance is improved.

Drawings

FIG. 1 is an SEM image of a precursor prepared in example 1 of the present invention;

FIG. 2 is a sectional view of a precursor prepared in example 1 of the present invention;

FIG. 3 is an SEM image of a precursor prepared in example 2 of the present invention;

FIG. 4 is a cross-sectional view of a precursor prepared in example 2 of the present invention.

Detailed Description

The invention is further described with reference to the following figures and examples:

the present disclosure will be described in detail below, and it is to be understood that variations and modifications can be made by the techniques taught in the present disclosure without departing from the spirit and scope of the present disclosure by those skilled in the art after understanding the present disclosure.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure.

As used herein, the term (terms), unless otherwise indicated, shall generally have the ordinary meaning as commonly understood by one of ordinary skill in the art, in this written description and in the claims. Certain words used to describe the disclosure are discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art in describing the disclosure.

Example 1:

a preparation method of a small-particle ternary precursor sequentially comprises the following steps:

preparing Ni, Co and Mn metal liquid, wherein the total molar concentration of Ni, Co and Mn is 1.8mol/L, and the molar ratio of Ni, Co and Mn elements is 60:10: 30;

preparing 20-40% by mass of sodium hydroxide or potassium hydroxide solution as a precipitator;

preparing an ammonia water solution with the mass fraction of 2-6% as a complexing agent;

adding alumina particles with the particle size of 0.9um serving as seed crystals with the concentration of 0.3g/L into a closed synthesis kettle, adding the sodium hydroxide or potassium hydroxide solution, pure water and the ammonia water solution to prepare a base solution, controlling the pH value of the base solution to be 11.00-11.60, maintaining the temperature at 40-60 ℃, and controlling the ammonia concentration in the base solution to be 0.25 mol/L;

step three, keeping stirring of the synthesis kettle open, continuously adding the metal liquid, the precipitator and the complexing agent in the step one into the synthesis kettle at the flow rate of 200-800 mL/min respectively for coprecipitation reaction, keeping the pH value in the reaction process at 11.00-11.60, keeping the reaction temperature at 40-60 ℃, keeping the rotation speed of the synthesis kettle at 550r/min, stopping feeding liquid when the target particle size is reached, adjusting the temperature of the synthesis kettle to 70-80 ℃, adjusting the pH value to 12.50-13.50 for aging, and aging for 3-4 hours to obtain a coprecipitation product;

step four, carrying out filter pressing, washing and drying on the coprecipitation product in the step three to obtain a ternary precursor with a hollow interior, wherein the chemical formula of the product is Ni_0.60Co_0.10Mn_0.30(OH)₂D50 is 4.52um, and the tap density is 1.75g/cm³The specific surface area is 12.35m²The data are shown in Table 1.

Example 2:

a preparation method of a small-particle ternary precursor sequentially comprises the following steps:

preparing Ni, Co and Mn metal liquid, wherein the total molar concentration of Ni, Co and Mn is 1.8mol/L, and the molar ratio of Ni, Co and Mn elements is 82:6: 12;

preparing 20-40% by mass of sodium hydroxide or potassium hydroxide solution as a precipitator;

preparing an ammonia water solution with the mass fraction of 2-6% as a complexing agent;

adding alumina particles with the particle size of 0.8um serving as seed crystals with the concentration of 0.25g/L into a closed synthesis kettle, adding the sodium hydroxide or potassium hydroxide solution, pure water and the ammonia water solution to prepare a base solution, controlling the pH value of the base solution to be 11.00-11.60, maintaining the temperature at 40-60 ℃, and controlling the ammonia concentration in the base solution to be 0.32 mol/L;

step three, keeping stirring of the synthesis kettle open, continuously adding the metal liquid, the precipitator and the complexing agent in the step one into the synthesis kettle at the flow rate of 200-800 mL/min respectively for coprecipitation reaction, keeping the pH value in the reaction process at 11.00-11.60, keeping the reaction temperature at 40-60 ℃, stopping feeding liquid when the pH value reaches the target granularity, adjusting the temperature of the synthesis kettle to 70-80 ℃, and aging the pH value to 12.50-13.50 for 3-4 hours, wherein the pH value in the reaction process is kept at 11.00-11.60, the reaction temperature is kept at 40-60 ℃, and the liquid feeding is stopped when the pH value reaches the target granularity;

step four, the coprecipitation product in the step three is treatedThrough filter pressing, washing and drying, a ternary precursor with a hollow interior is obtained, and the chemical formula of the product is Ni_0.82Co_0.06Mn_0.12(OH)₂D50 is 3.56um, and the tap density is 1.57g/cm³The specific surface area is 18.26m²The data are shown in Table 1.

TABLE 1 Final product data for the products obtained in the examples

Comparing the data of each example in table 1 shows that: under the condition of similar particle sizes of alumina, the tap density of the product has a certain positive correlation with the particle size, and the specific surface area of the product is in a negative correlation.

Fig. 1 to 4 are a field emission electron microscope image and a cross-sectional electron microscope image of the products prepared in examples 1 and 2, respectively, and it can be seen from the images that the alumina in the ternary precursor is completely dissolved under a higher pH condition, and a hollow structure is formed in the ternary precursor. Since example 1 uses alumina having a larger particle size than example 2, the pores in example 1 are larger than those in example 2, which also illustrates that the size of the alumina particle determines the pore size of the ternary precursor.

The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.