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CN-117602681-B - Porous structure multi-element precursor and preparation method thereof

CN117602681BCN 117602681 BCN117602681 BCN 117602681BCN-117602681-B

Abstract

The invention discloses a porous structure multielement precursor, which has a chemical general formula of Ni x Mn y Mo z (OH) 2 and has the characteristic of controllable structure. The invention also discloses a preparation method of the porous precursor with the porous structure, which comprises the following steps of preparing a solution A, a solution B, a solution C and a solution D, adding pure water into a reaction kettle, introducing nitrogen for replacement, heating, adding the solution B and the solution C as base solution, adding the solution A for nucleation, adding the solution B and the solution C, introducing the doping agent D after nucleation is finished to obtain porous precursor slurry, and carrying out solid-liquid separation, washing, drying and sieving on the precursor slurry to obtain the porous precursor. The method is easy to control in process, is suitable for industrial production, and solves the problem that the internal structure of the precursor is uncontrollable through the cooperative control of the oxygen content and the structure regulator.

Inventors

  • ZHANG PEIQI
  • CHEN WEIWEI
  • ZHANG CHENG
  • Kou liang
  • DU MENGQI
  • LIU ZENG
  • ZHU DUANXU

Assignees

  • 泾河新城陕煤技术研究院新能源材料有限公司

Dates

Publication Date
20260508
Application Date
20231123

Claims (8)

  1. 1. The preparation method of the porous structure multi-element precursor is characterized by comprising the following steps of: step 1, preparing a metal salt solution A of nickel and manganese, preparing a precipitant sodium hydroxide solution B, preparing a complexing agent solution C, preparing a doped metal salt solution D; step 2, adding pure water into the reaction kettle, introducing nitrogen for replacement for a certain time, heating to a required temperature, adding the solution B and the solution C prepared in the step 1 into the reaction kettle, and adjusting to design conditions as base solution; Step 3, firstly adding the solution A into the adjusted base solution to nucleate, adding the solution B and the solution C in the process to maintain the pH value and the ammonia value in a design range, preparing a loose core according to the requirement, introducing the doping agent D after the nucleation is finished to reduce environmental fluctuation in a nucleation stage, stabilizing the process, and adjusting the rotating speed according to the growth condition in the process until reaching a target particle size to stop the reaction to obtain loose porous precursor slurry; in the step 3, the pH value in the reaction process is maintained at 11.0-12.0, the ammonia concentration is maintained at 0.10 mol/L-0.40 mol/L, the stirring speed is 100 rpm-700 rpm, and a mixed atmosphere of nitrogen and air is conveyed into a reaction kettle to form micro oxidation, so that a loose structure from inside to outside is controlled; And 4, carrying out solid-liquid separation, washing, drying and sieving on the precursor slurry prepared in the step 3 to obtain a multi-element precursor.
  2. 2. The method for preparing porous structure porous precursor according to claim 1, wherein in step 1, the nickel and manganese salts of the metal salt solution a are selected from at least one of sulfate, halogen salt or nitrate, the precipitant B is sodium hydroxide, the complexing agent solution C is ammonia water, and the dopant solution D is at least one of ammonium molybdate or sodium molybdate.
  3. 3. The method for preparing a porous structure porous precursor according to claim 1, wherein in the step 1, the concentration of the metal salt solution A is 1.0mol/L to 3.0mol/L, the concentration of the precipitant sodium hydroxide solution B is 5mol/L to 15mol/L, the concentration of the complexing agent solution C is 4mol/L to 14mol/L, and the concentration of the doped metal salt solution D is 1.0mol/L to 3.0mol/L.
  4. 4. The method for preparing a porous structure porous precursor according to claim 1, wherein in the step2, the pure water is added in an amount of 1/3-4/5 of the volume of the reaction kettle, the nitrogen substitution flow is 100 ml/min-500 ml/min, the nitrogen substitution time is 4 h-10 h, the required temperature in the reaction kettle is 45-70 ℃, and the design condition is that the pH value is 11.8-12.5.
  5. 5. The method for preparing a porous structure porous precursor according to claim 1, wherein the flow rates of the metal salt solution a and the doped metal solution D used in the step 3 are 0.9L/h to 4.8L/h.
  6. 6. The method for preparing a porous structure porous precursor according to claim 5, wherein in the step 3, four-way feeding is adopted for the metal salt solution A, the precipitant sodium hydroxide solution B, the complexing agent solution C and the doped metal salt solution D, the shutdown granularity is 2.5-5.0 um, and the precursor ratio is 10m 2 /g ~40m 2 /g.
  7. 7. The method of preparing a porous precursor according to claim 6, wherein in step 3, the precursor has a chemical formula of ：Ni x Mn y Mo z (OH) 2 ,0.5<x<0.9,0<y<0.5,0<z<0.05,x+z+y=1.
  8. 8. The method for preparing the porous structure porous precursor according to claim 1, wherein in the step 4, solid-liquid separation, washing, drying and sieving are performed on the prepared precursor slurry, the solid-liquid separation is performed by adopting a centrifugal machine, washing is performed for multiple times by using hot alkali and hot water at 60-80 ℃, the concentration of the adopted washing hot alkali is 1.0 mol/L-4.0 mol/L, the consumption of the hot water and the hot alkali is 10-20 times that of the precursor material until the content of impurity Na in the precursor material is lower than 150ppm, the content of impurity S is lower than 2000ppm, the drying temperature of an oven is 80-120 ℃ after the washing is finished, and the moisture is lower than 1.0wt% for screening and split charging.

Description

Porous structure multi-element precursor and preparation method thereof Technical Field The invention belongs to the technical field of lithium ion battery anode materials, relates to a porous structure multi-element precursor for a lithium ion battery, and further relates to a preparation method of the porous structure multi-element precursor for the lithium ion battery. Background Lithium ion batteries have become an indispensable energy medium in modern society as an energy storage solution with high efficiency, light weight, high energy density and repeatable charge and discharge. The method is widely applied to the fields of mobile electronic equipment, electric automobiles, energy storage systems, renewable energy facilities and the like, has profound effects on our life style and environment, and along with continuous improvement of life quality of people, the requirements on the anode material are higher and higher, so that the performance of the anode material is improved further. The current positive electrode material has the following problems that 1, lithium ions which are continuously intercalated/deintercalated in the circulation process can expand and contract the positive electrode material, mechanical stress is caused in the material, the microstructure of the positive electrode material becomes unstable due to repeated mechanical stress, cracks and particles are finally separated, the service life and the performance of a battery are reduced, and 2, the material performance is attenuated due to the change of the structure of the positive electrode material, the formation of a solid phase interface, the infiltration of electrolyte into the cracks and other side reactions. In addition, the migration rate of lithium ions is closely related to the morphology and arrangement compactness of primary particles, and the compact stacking mode is easy to cause the increase of resistance in the ion migration process, so that the rate capability of the material is obviously affected. It is well known that the morphology of the positive electrode material is determined in large part by the upstream precursor, and that the internal morphology is more important for the sintering performance of the positive electrode material than the surface morphology of the precursor. Therefore, in the most widely used technology of the ternary precursor coprecipitation method in industrialization, the addition of the structure regulator is particularly important to realize the controllable internal structure of the product. The Chinese patent publication No. CN115340133A, publication No. 2022.11.15 discloses a molybdenum doped nickel-rich ternary precursor and a preparation method thereof, and when the ternary precursor is prepared, the adopted additive has rich carboxylic acid groups in the molecular structure to limit the growth of primary particles, and the doped Mo element reduces the formation of isolated oxygen, can effectively avoid the loss of lattice oxygen during long-term circulation and stabilizes the structure. However, the additives used in the process increase the production and transportation costs, and the newly introduced additives are liable to affect the quality of the product and bring impurities. Chinese patent publication No. CN115924988a, publication No. 2023.04.07 discloses a ternary precursor with core-shell structure, a preparation method thereof, and a monocrystal, wherein a trace amount of air is introduced to form a core pore effect, and the shell is doped with elements to prepare a thicker sawtooth shell layer to prepare the monocrystal morphology. Although the natural oxidation adopted in the method realizes the internal pore effect, the oxidation degree is difficult to control, the appearance influence is larger under different manganese contents, the batch stability is not facilitated, and the later process is difficult to amplify. At present, the layered oxide precursor material prepared by the coprecipitation method is easy to generate multi-sphere adhesion under small particle size, so that micro powder is easy to generate after sintering due to poor sphericity, secondary spheres are gradually compacted after synthesis time is prolonged and solid content is increased, lithium mixing is uneven, lithium ions in the positive electrode material are difficult to insert/extract after sintering, internal stress is difficult to release due to a compact structure, and micro cracks in crystal grains are generated. There is an urgent need to develop precursors with controllable internal structures, which are simple in operation process, promote more uniform contact in the lithium mixing process so as to reduce surface residual lithium, effectively release stress in the cyclic process, promote rapid migration of lithium ions in the charge and discharge process, and improve electrochemical performance of materials. Disclosure of Invention The first object of the invention is to provide a porous