CN-122010201-A - Lithium-rich manganese-based positive electrode material precursor, preparation method and lithium-rich manganese-based positive electrode material

CN122010201ACN 122010201 ACN122010201 ACN 122010201ACN-122010201-A

Abstract

The invention discloses a lithium-rich manganese-based positive electrode material precursor, a preparation method and a lithium-rich manganese-based positive electrode material, wherein the lithium-rich manganese-based positive electrode material precursor comprises secondary particles composed of primary particles, the primary particles comprise flaky primary particles and slatted primary particles, the average thickness of the flaky primary particles is 20-80 nm, the average length of the flaky primary particles is 100-500 nm, the slatted primary particles are positioned in the lithium-rich manganese-based positive electrode material precursor, the average thickness of the slatted primary particles is 110-150 nm, and the average length of the slatted primary particles is 800-1200 nm. According to the lithium-rich manganese-based positive electrode material precursor, the structure formed by synergetically assembling the flaky and lath-shaped primary particles is beneficial to considering tap density, structural strength and reactivity, the technical bottleneck that the capacity and the cycle performance of the positive electrode material prepared by the traditional precursor are difficult to consider is overcome, and the comprehensive electrochemical performance of the positive electrode material prepared subsequently is improved.

Inventors

LI DING
Deng Ruichao
LIU GENGHAO
RUAN DINGSHAN

Assignees

广东邦普循环科技有限公司
湖南邦普循环科技有限公司
宜昌邦普循环科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260226

Claims (10)

1. The precursor of the lithium-rich manganese-based positive electrode material is characterized by comprising secondary particles composed of primary particles, wherein the primary particles comprise flaky primary particles and lath-shaped primary particles, the average thickness of the flaky primary particles is 20-80 nm, the average length of the flaky primary particles is 100-500 nm, the lath-shaped primary particles are positioned in the precursor of the lithium-rich manganese-based positive electrode material, the average thickness of the lath-shaped primary particles is 110-150 nm, and the average length of the lath-shaped primary particles is 800-1200 nm.
2. The lithium-rich manganese-based positive electrode material precursor according to claim 1, wherein the secondary particles sequentially comprise a core, a middle layer and a surface layer from inside to outside, and the porosity of the core and the surface layer is smaller than that of the middle layer; And/or the secondary particles sequentially comprise an inner core, a middle layer and a surface layer from inside to outside, wherein the average pore diameter of the inner core and the surface layer is smaller than that of the middle layer; And/or the secondary particles sequentially comprise an inner core, a middle layer and a surface layer from inside to outside, wherein the lath-shaped primary particles are mainly distributed in the middle layer; and/or, in the section of the secondary particles, the proportion of the area of the lath-shaped primary particles to the total area of the section is 30% -80%.
3. The lithium-rich manganese-based positive electrode material precursor according to claim 1, wherein the sphericity of the secondary particles is 0.8 to 0.9; and/or the molecular formula of the precursor of the lithium-rich manganese-based positive electrode material is Mn x Ni 1-x (OH) 2 , wherein x is more than or equal to 0.5 and less than or equal to 0.8; and/or the Dv50 of the precursor of the lithium-rich manganese-based positive electrode material is 5.0-7.0 mu m; And/or the porosity of the lithium-rich manganese-based positive electrode material precursor is 3.0% -6.0%; and/or the diameter distance of the precursor of the lithium-rich manganese-based positive electrode material is 0.3-0.4; and/or the specific surface area of the lithium-rich manganese-based positive electrode material precursor is 22-36 m 2 /g; and/or the average value of the aspect ratio of the secondary particles is 1.1-1.2; and/or the tap density of the precursor of the lithium-rich manganese-based positive electrode material is 1.3-1.7 g/cm 3 .
4. A method for preparing the lithium-rich manganese-based positive electrode material precursor according to any one of claims 1 to 3, comprising: A nucleation stage, in which mixed metal salt solution and precipitant solution are added in parallel flow to a base solution containing precipitant under the conditions of protective atmosphere and stirring, and the pH value of a reaction system is maintained at 10.0-11.0, so as to obtain a section of slurry; In the growth stage, under the conditions of protective atmosphere and stirring, continuously feeding a mixed metal salt solution, gradually reducing the flow rate of a precipitant solution to gradually reduce the pH of a reaction system to 8.67-9.33, and maintaining the pH to 8.67-9.33 and Dv50 to 2.0-4.0 um to obtain a second-stage slurry; Under the conditions of protective atmosphere and stirring, the flow of the mixed metal salt solution and the precipitant is increased, so that the pH of a reaction system is increased by 0.3-1.0 compared with the pH of the second-stage slurry within 1-10 min, and the structure-induced slurry containing lath-shaped primary particles is obtained; continuing to grow, under the conditions of protective atmosphere and stirring, continuing to flow a mixed metal salt solution into the structure induction slurry, and reducing the flow rate of a precipitant solution to maintain the pH value of a reaction system at 8.67-9.33, so as to obtain target slurry; And (3) carrying out aftertreatment, aging, washing and drying on the target slurry in sequence under the protection atmosphere condition to obtain the precursor of the lithium-rich manganese-based positive electrode material.
5. The method for preparing a lithium-rich manganese-based positive electrode material precursor according to claim 4, wherein the mixed metal salt solution comprises nickel ions and manganese ions, and the molar ratio of nickel to manganese is (1-x): x, x is more than or equal to 0.5 and less than or equal to 0.8; And/or the total concentration of metal ions in the mixed metal salt solution is 100 g/L-120 g/L; And/or the precipitant is at least one selected from sodium hydroxide, sodium carbonate, potassium hydroxide and lithium hydroxide; And/or the pH of the base solution is 10.10-10.70; and/or the volume ratio of the base solution to the reactor is 80% -95%.
6. The method of preparing a lithium-rich manganese-based positive electrode material precursor according to claim 4, wherein the flow rate of the mixed metal salt solution in the nucleation stage and the growth stage is 0.097mol/h/L Reactor for producing a catalyst ~0.103 mol/h/L Reactor for producing a catalyst ; and/or stirring at 450-550 rpm; and/or, the nucleation time is 30-120 min.
7. The method for preparing the lithium-rich manganese-based positive electrode material precursor according to claim 4, wherein the nucleation stage, the growth stage, the structure induction and the continuous growth step all introduce a protective gas into the reactor, and the amount of the protective gas introduced per hour is 1% -3% of the volume of the reactor; And/or, the post-treatment step is to introduce a protective gas into the equipment, wherein the amount of the protective gas introduced per hour is 1% -5% of the volume of the equipment.
8. The method for preparing a lithium-rich manganese-based positive electrode material precursor according to claim 4, wherein the time of the structure induction step is 1-60 min; And/or the pH reduction rate in the growth stage is 0.02/30 min-0.06/30 min; and/or the pH of the structure inducing step is less than the pH of the nucleation stage; and/or, in the structure induction step and the continuous growth step, the flow rate of the mixed metal salt solution is 0.133mol/h/L Reactor for producing a catalyst ~0.183 mol/h/L Reactor for producing a catalyst .
9. The method for preparing a lithium-rich manganese-based positive electrode material precursor according to claim 4, wherein in the continuous growth step, when the solid content of the reaction system reaches 400-500 g/L for the first time, the solid content is adjusted to 150-300 g/L, and then the coprecipitation step is continued; and/or the solid content of the target slurry is 550 g/L-750 g/L; and/or testing the color of the target slurry by using a Lab color difference meter, wherein the L value is 50-60, the a value is 2-7, and the b value is 19-24.
10. A lithium-rich manganese-based positive electrode material, characterized in that a raw material comprises the lithium-rich manganese-based positive electrode material precursor according to any one of claims 1 to 3.

Description

Lithium-rich manganese-based positive electrode material precursor, preparation method and lithium-rich manganese-based positive electrode material Technical Field The invention relates to the technical field of battery materials, in particular to a precursor of a lithium-rich manganese-based positive electrode material, a preparation method and the lithium-rich manganese-based positive electrode material. Background With the rapid development of the fields of new energy automobiles, large-scale energy storage and the like, the market has raised higher requirements on the energy density, the cycle life and the cost of lithium ion batteries. The lithium-rich manganese-based positive electrode material has the advantages of high specific capacity and low cost exceeding 250 mAh/g in theory, and is considered as one of the key positive electrode materials of the next-generation high-energy-density lithium ion battery. However, commercial applications still face a serious series of challenges including firstly, low first-turn efficiency, serious voltage decay, poor cycle performance and other long-standing problems, and secondly, the pursuit of high capacity often results in lower compaction density of materials, thereby limiting the improvement of volumetric energy density of the battery. The root of these problems is closely related to the instability of the crystal structure of the material itself and the phase change during lithium ion deintercalation. As a basis for the preparation of lithium-rich manganese-based materials, the physical and chemical properties of the precursor (typically manganese-nickel-based hydroxide), such as morphology, particle size, porosity, tap density and microstructure, directly determine the properties of the final sintered product. At present, most of precursors prepared by a conventional coprecipitation method are spherical secondary particles formed by agglomeration of primary particles. In order to increase the specific surface area to increase the reactivity, it is generally necessary to decrease the primary particle size or increase the porosity, but this tends to result in a decrease in the tap density of the precursor and a decrease in the structural strength. In the subsequent high-temperature sintering and battery cycle process, the anode material derived from the precursor with unstable structure is easy to generate particle breakage or structural collapse, and the accelerated performance decline is realized. Conversely, if high tap density and high structural strength are simply pursued, the reactivity and specific capacity of the material may be sacrificed. Therefore, how to design and prepare a lithium-rich manganese-based precursor with high reactivity and high structural stability, and realize the synergistic optimization of the capacity, the cycle life and the compaction density of the positive electrode material prepared by the lithium-rich manganese-based precursor becomes a key technical problem to be solved in the field. Disclosure of Invention The invention aims to provide a precursor of a lithium-rich manganese-based positive electrode material, a preparation method and the lithium-rich manganese-based positive electrode material, which are beneficial to considering tap density and reactivity. The invention is realized in the following way: The invention provides a lithium-rich manganese-based positive electrode material precursor, which comprises secondary particles composed of primary particles, wherein the primary particles comprise flaky primary particles and lath-shaped primary particles, the average thickness of the flaky primary particles is 20-80 nm, the average length of the flaky primary particles is 100-500 nm, the lath-shaped primary particles are positioned in the lithium-rich manganese-based positive electrode material precursor, the average thickness of the lath-shaped primary particles is 110-150 nm, and the average length of the lath-shaped primary particles is 800-1200 nm. In an alternative embodiment, the secondary particles sequentially comprise a core, a middle layer and a surface layer from inside to outside, wherein the porosity of the core and the surface layer is smaller than that of the middle layer; And/or the secondary particles sequentially comprise an inner core, a middle layer and a surface layer from inside to outside, wherein the average pore diameter of the inner core and the surface layer is smaller than that of the middle layer; And/or the secondary particles sequentially comprise an inner core, a middle layer and a surface layer from inside to outside, wherein the lath-shaped primary particles are mainly distributed in the middle layer; and/or, in the section of the secondary particles, the proportion of the area of the lath-shaped primary particles to the total area of the section is 30% -80%. In an alternative embodiment, the sphericity of the secondary particles is 0.8-0.9; and/or the molecular formula of the precurs