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CN-122010200-A - Bulk phase gradient high-aluminum doped lithium-rich manganese precursor, preparation method and application

CN122010200ACN 122010200 ACN122010200 ACN 122010200ACN-122010200-A

Abstract

The invention discloses a bulk phase gradient high-aluminum doped lithium-rich manganese precursor, a preparation method and application thereof, wherein the chemical general formula of the precursor is Mn x Ni y Co 1‑x‑y (OH) 2 or Mn x Ni y Co 1‑x‑y CO 3 , x is 0.6-0.8, y is 0.2-0.4, the structure comprises an inner core layer, an intermediate layer and a shell layer, the total doping amount of aluminum element is 10000-20000 ppm, and the doping concentration of aluminum is continuously increased in a gradient manner from inside to outside. The preparation method comprises the steps of simultaneously introducing a manganese-based mixed salt solution, a precipitator solution, a complexing agent solution and a first-concentration aluminum solution into a base solution, performing a first coprecipitation reaction to complete nucleation and form an inner core layer, introducing a second-concentration aluminum solution into the inner core layer system, performing a second coprecipitation reaction to realize crystal growth of an intermediate layer, and finally switching to a third-concentration aluminum solution to perform a third coprecipitation reaction to complete crystal growth and aging of a shell layer, thereby finally obtaining the gradient doped lithium-rich manganese precursor. The material is used for manufacturing a battery anode.

Inventors

  • JIANG MIN
  • WANG BO
  • LIN ZIHUA
  • CHEN WEIPENG

Assignees

  • 深圳市速方新能源科技有限公司

Dates

Publication Date
20260512
Application Date
20260213

Claims (7)

  1. 1. A bulk phase gradient high-aluminum doped lithium-rich manganese precursor is characterized by having a chemical general formula of Mn x Ni y Co 1-x-y (OH) 2 or Mn x Ni y Co 1-x-y CO 3 , wherein x is 0.6-0.8, y is 0.2-0.4, structurally comprises an inner core layer, an intermediate layer and a shell layer from inside to outside, the total doping amount of aluminum element is 10000-20000 ppm, and the doping concentration of aluminum is continuously increased in a gradient manner from inside to outside.
  2. 2. The bulk phase gradient high-alumina doped lithium-manganese-rich precursor according to claim 1, wherein the particle sizes of an inner core layer, an intermediate layer and a shell layer of the precursor are distributed in a gradient manner, wherein the D50 of the inner core layer is 2.0-4.0 mu m, the D50 of the intermediate layer is 8.0-11.0 mu m, and the D50 of the shell layer is 12.0-15.0 mu m.
  3. 3. A method for preparing the bulk-phase gradient high-aluminum-doped lithium-manganese-rich precursor according to claim 1, which is characterized in that: S1, simultaneously introducing a manganese-based mixed salt solution, a precipitator solution, a complexing agent solution and a first-concentration aluminum solution into a base solution, and performing a first coprecipitation reaction to complete nucleation and form a core layer, wherein the temperature during the first coprecipitation reaction is 50-55 ℃, and the pH value is 8.0-8.1; S2, introducing a second concentration aluminum solution into the kernel layer system to perform a second coprecipitation reaction to realize crystal growth of the middle layer, wherein the temperature during the second coprecipitation reaction is 56-58 ℃, and the pH value is 8.2-8.3; S3, switching to a third-concentration aluminum solution, performing a third coprecipitation reaction, completing crystal growth and aging of a shell layer, and finally obtaining the gradient doped lithium-rich manganese precursor, wherein the temperature is 59-62 ℃ and the pH value is 8.4-8.6 during the third coprecipitation reaction; the first coprecipitation reaction, the first coprecipitation reaction and the third coprecipitation reaction are all completed under the nitrogen atmosphere; Wherein, the concentration of the third concentration aluminum solution is higher than the concentration of the second concentration aluminum solution is higher than the concentration of the first concentration aluminum solution, so that the doping concentration of aluminum in the inner core layer, the middle layer and the shell layer is continuously increased in a gradient manner.
  4. 4. The method of claim 3, wherein the complexing agent solution is any one of ammonia water, citric acid, sodium oxalate and EDTA or a mixed solution of at least two of them in any ratio, the precipitant solution is sodium oxide solution or sodium carbonate solution, the concentration of sodium hydroxide solution or sodium carbonate solution is 2mol/L, and the concentration of complexing agent solution is 10g/L.
  5. 5. The method of claim 3, wherein the manganese-based mixed salt solution is a soluble aqueous solution of nickel salt, cobalt salt and manganese salt, and the total metal ion concentration of the manganese-based mixed salt solution is 2.0-2.2mol/L.
  6. 6. The method of claim 5, wherein the nickel salt, cobalt salt and manganese salt are nickel sulfate, cobalt sulfate and manganese sulfate, respectively.
  7. 7. The application of the bulk phase gradient high-alumina doped lithium-rich manganese precursor according to claim 1 or 2, which is characterized in that the bulk phase gradient high-alumina doped lithium-rich manganese precursor is mixed with a lithium source for sintering to obtain the lithium-rich manganese-based positive electrode material, wherein the sintering process is that the temperature is raised to the presintering temperature at the heating rate of 2-5 ℃ per minute, the temperature is kept for 1-2h at 300-500 ℃ to fully remove volatile matters and realize preliminary oxidation, and then the temperature is raised to 700-850 ℃ at 5 ℃ per minute, and the temperature is kept for 8-12h.

Description

Bulk phase gradient high-aluminum doped lithium-rich manganese precursor, preparation method and application Technical Field The invention belongs to the technical field of lithium ion battery anode battery materials, and particularly relates to a bulk phase high-aluminum doped lithium-rich manganese precursor, a preparation method and application thereof. Background With the rapid development of the fields of new energy automobiles, large-scale energy storage and the like, the market has put forward higher requirements on the energy density, the cycling stability and the safety of lithium ion batteries. The lithium-rich manganese-based positive electrode material is regarded as one of important candidate materials of next-generation high-energy-density lithium ion batteries because of the advantages of ultra-high specific capacity (theoretical specific capacity is more than 250 mAh/g), low cost, environmental friendliness and the like. However, the lithium-rich manganese-based material still has obvious defects in practical application, namely, manganese element is easy to dissolve in the circulation process, so that the material structure gradually collapses, the circulation stability is reduced, and the problems of rapid capacity attenuation, low first coulomb efficiency, easiness in volume expansion and microcracking in the circulation and the like are commonly existed, so that the large-scale application of the lithium-rich manganese-based material is restricted. To ameliorate the above problems, aluminum doping is often employed in the industry to modify, either by occupying lattice sites with aluminum atoms or by forming stable phases to enhance structural stability. At present, most common aluminum doping modes are surface doping, and although certain protection can be formed on the surface of a material, aluminum elements are unevenly distributed, have weak binding force with a matrix and are easy to lose effectiveness after long-term circulation. In addition, the aluminum doping amount in the existing lithium-rich manganese anode material is generally less than 10000ppm, and the stabilization effect of aluminum on the material structure is difficult to fully play. Therefore, the development of the preparation method of the lithium-rich manganese precursor which can realize high aluminum doping of the bulk phase, controllable component gradient and stable structure becomes a key way for breaking through the application bottleneck of the lithium-rich manganese-based material. Disclosure of Invention The invention aims to solve the problems of uneven aluminum doping distribution, poor structural stability, insufficient cycle performance and the like of the existing lithium-rich manganese precursor, and provides a bulk phase gradient high-aluminum doping lithium-rich manganese precursor and a preparation method thereof. In order to achieve the above object, the technical scheme of the present invention is as follows: The bulk phase gradient high-aluminum doped lithium-manganese-rich precursor has a chemical general formula of Mn xNiyCo1-x-y(OH)2 or Mn xNiyCo1-x-yCO3, wherein x is 0.6-0.8, y is 0.2-0.4, structurally, the bulk phase gradient high-aluminum doped lithium-manganese-rich precursor comprises an inner core layer, an intermediate layer and a shell layer from inside to outside, the total doping amount of aluminum element is 10000-20000 ppm, and the doping concentration of aluminum is continuously increased in a gradient manner from inside to outside. As an improvement to the technical scheme, the particle sizes of the inner core layer, the middle layer and the shell layer of the precursor are distributed in a gradient mode, wherein the D50 of the inner core layer is 2.0-4.0 mu m, the D50 of the middle layer is 8.0-11.0 mu m, and the D50 of the shell layer is 12.0-15.0 mu m. The invention also provides a preparation method of the bulk phase gradient high-aluminum doped lithium-rich manganese precursor, which comprises the following steps: S1, simultaneously introducing a manganese-based mixed salt solution, a precipitator solution, a complexing agent solution and a first-concentration aluminum solution into a base solution, performing a first coprecipitation reaction, completing nucleation and forming an inner core layer (corresponding to a seed crystal preparation stage), wherein the temperature is 50-55 ℃, the pH value is 8.0-8.1, and the concentration of the aluminum solution is 0.3-0.4g/L; S2, introducing a second concentration aluminum solution (the concentration is higher than the first concentration) into the inner nuclear layer system, and performing a second coprecipitation reaction to realize the crystal growth of the intermediate layer, wherein the temperature is 56-58 ℃, the pH value is 8.2-8.3, and the concentration of the aluminum solution is 0.4-0.5g/L; S3, switching to a third-concentration aluminum solution (the concentration is higher than the second concentration), performing