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CN-122010196-A - Preparation method of lithium nickel manganese oxide positive electrode material with controllable particle size

CN122010196ACN 122010196 ACN122010196 ACN 122010196ACN-122010196-A

Abstract

The invention relates to the technical field of lithium battery anode materials, in particular to a preparation method of a lithium nickel manganese oxide anode material with a controllable particle size. The method comprises the steps of carrying out freeze drying on wet gel prepared by a sol-gel method for primary dewatering, carrying out vacuum drying for secondary dewatering, and carrying out high-temperature sintering on a dewatered solid product in an air atmosphere to obtain the monocrystal particle lithium nickel manganese oxide anode material with the particle size of 200 nanometers-2 microns. The primary dewatering of the wet gel synthesized by the sol-gel method by the freeze-drying method can effectively limit the growth of crystal grains, the secondary dewatering of the vacuum drying temperature after the freeze-drying is further regulated, the porosity degree of the xerogel can be regulated and controlled, and the lithium nickel manganese oxide particles with controllable particle sizes are obtained. According to the preparation method of the high-performance lithium nickel manganese oxide anode material with controllable particle size, 1-micrometer 'circulating' lithium nickel manganese oxide and 500-nanometer 'multiplying power' lithium nickel manganese oxide which are suitable for different working scenes are preferably prepared.

Inventors

  • PU NAN
  • Wu Huize
  • HU GUANGJIAN
  • LI FENG

Assignees

  • 中国科学院金属研究所

Dates

Publication Date
20260512
Application Date
20260119

Claims (10)

  1. 1. A preparation method of a lithium nickel manganese oxide positive electrode material with controllable particle size is characterized in that a wet gel prepared by a sol-gel method is subjected to freeze drying for primary water removal, vacuum drying is used for secondary water removal, and a solid product after water removal is subjected to high-temperature sintering in an air atmosphere to obtain a monocrystal particle lithium nickel manganese oxide positive electrode material with the particle size of 200-2 microns.
  2. 2. The preparation method of the wet gel according to claim 1 is characterized by comprising the steps of preparing aqueous solution of lithium nitrate, nickel nitrate hexahydrate and manganese nitrate hexahydrate, wherein the total concentration of metal ions is 1-2 mol/L, the molar ratio of metal elements is Li: ni: mn= (20-24): 10:30, dropwise adding aqueous solution of citric acid into the aqueous solution, the aqueous solution of citric acid is 2.5-3.5 mol/L, the molar ratio of citric acid to metal cations is (2.5-3.5): 1, heating and stirring the mixed solution in a water bath at 60-80 ℃ for 5-8 hours, and the stirring speed is 200-400 r/min.
  3. 3. The preparation method according to claim 2, wherein the wet gel is subjected to freeze drying once to remove water, the freezing temperature is-20 to-40 ℃, the freeze drying time is 12-48 hours, and the vacuum degree is 50-300 mTorr.
  4. 4. The preparation method according to claim 3, wherein the secondary water removal is performed by vacuum drying at 80-150 ℃ for 36-48 hours.
  5. 5. The preparation method of the ceramic powder according to claim 4, wherein the solid product after water removal is sintered at a high temperature in an air atmosphere, and the sintering process is divided into two steps, wherein the primary sintering temperature is 400-500 ℃, the sintering time is 5-7 hours, the heating rate is 8-10 ℃ per minute, the secondary sintering temperature is 850-950 ℃, the sintering time is 10-12 hours, and the heating rate is 8-10 ℃ per minute.
  6. 6. The preparation method of the lithium nickel manganese oxide positive electrode material is characterized in that the particle size of the lithium nickel manganese oxide positive electrode material is controllable by adjusting the drying temperature of vacuum drying and secondary water removal, wherein the particle size is obtained by performing high-temperature sintering after vacuum drying at 120-150 ℃, and the particle size is obtained by performing high-temperature sintering after vacuum drying at 80-120 ℃.
  7. 7. The preparation method of the lithium nickel manganese oxide cathode material is characterized in that when the solid product is subjected to high-temperature sintering in an air atmosphere, the primary sintering is carried out for 6 hours at 450 ℃ and the secondary sintering is carried out for 10 hours at 900 ℃ to obtain the circular lithium nickel manganese oxide cathode material with the particle size of 1 micron; or freeze drying at-40 ℃ for 48 hours when primary dewatering is performed, vacuum drying at 80 ℃ for 48 hours when secondary dewatering is performed, and sintering at 450 ℃ for 6 hours and 900 ℃ for 10 hours when high-temperature sintering is performed on the dewatered solid product in an air atmosphere, so as to obtain the 'multiplying power' lithium nickel manganese oxide anode material with the particle size of 500 nanometers.
  8. 8. The preparation method according to any one of claims 1 to 7, wherein the lithium nickel manganese oxide positive electrode material is suitable for use in a wide temperature range, and the temperature range is-40 to 60 ℃.
  9. 9. The method according to any one of claims 1 to 7, wherein the lithium nickel manganese oxide positive electrode material is applied to a lithium ion battery or a lithium metal battery.
  10. 10. The preparation method according to claim 1, wherein the method is applied to lithium nickel manganese oxide, lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium cobalt oxide or lithium-rich manganese-based cathode materials prepared by a sol-gel method.

Description

Preparation method of lithium nickel manganese oxide positive electrode material with controllable particle size Technical Field The invention relates to the technical field of lithium battery anode materials, in particular to a preparation method of a lithium nickel manganese oxide anode material with a controllable particle size. Background Lithium nickel manganese oxide (chemical formula is LiNi 0.5Mn1.5O4) is one of the preferred positive electrode materials of high energy density lithium batteries because of its high voltage plateau (4.7V) and high theoretical energy density (650 Wh kg -1). Compared with lithium cobalt oxide and ternary nickel cobalt lithium manganate positive electrode, the nickel lithium manganate has the remarkable advantages of no cobalt, low cost and environmental friendliness. Meanwhile, the nickel lithium manganate spinel structure enables the diffusion rate of lithium ions in the material to be high, and has good electrochemical performance. However, the use of lithium nickel manganate is also accompanied by a series of challenges. The conventional lithium nickel manganese oxide material has the particle size of a plurality of micrometers, the lithium ion diffusion path is long, the multiplying power performance of the material is limited, meanwhile, the large particles have poor mechanical strength, the particles are easy to crack and lose efficacy in the circulation process, and the circulation life of the material is directly influenced. The patent of publication No. CN120622563A proposes a lithium nickel manganese oxide high-voltage single-stage positive electrode material based on ordered phase regulation and control and a preparation method thereof, wherein the average particle size of powder of the lithium nickel manganese oxide positive electrode material is 30-900 nm, and although the rate performance can be improved, too small particle size easily causes more side reactions, such as excessive electrolyte decomposition and formation of a thick interface layer, not only accelerates material capacity attenuation, but also can cause increase of internal resistance of a battery. Therefore, the lithium nickel manganese oxide anode material synthesized by the preparation method with controllable particle size is a core technology for solving the problems of poor mechanical strength caused by overlarge particle size and side reaction caused by overlarge particle size, so as to meet the use requirements under the conditions of long circulation and high multiplying power. The particle size of the lithium nickel manganese oxide anode material can be effectively controlled by adjusting the condition parameters in the material synthesis process. The sol-gel method is a common preparation method of lithium nickel manganese oxide, and the method can synthesize lithium nickel manganese oxide particles with uniform particle size and good dispersibility by adjusting parameters such as precursor concentration, pH value, reaction temperature and the like. The patent publication No. CN112421009A proposes a positive electrode material, a preparation method thereof and a secondary battery, wherein the pH value can be regulated to be neutral, the gelation temperature and the stirring rate can be regulated, and the patent publication No. CN111252813A proposes a positive electrode material of a lithium ion battery, and the vacuum degree and the temperature can be regulated. However, these conventional parameter adjustments only give particles of a specific size, and it is difficult to achieve a controllable particle size, which cannot meet the requirements under different conditions of use. Patent publication No. CN116812993A proposes a lithium nickel manganese oxide positive electrode material, a preparation method thereof and a secondary battery, and the particle size is regulated and controlled by depending on complexing agent and jet mill crushing, although D97 is less than or equal to 2 mu m, the jet mill crushing is easy to cause uneven particle aggregation, the particle size regulation and control precision is limited, and the problem of poor mechanical strength of large particles is difficult to solve. The patent of publication No. CN109704411A proposes a lithium nickel manganese oxide positive electrode material and a preparation method thereof, and particle size control is realized by a coprecipitation method and solid phase sintering, but the pH value of a reaction system is as high as 9.0-14.0, the process is complex, and the core contradiction that large particle diffusion path length and small particle side reaction are more cannot be balanced. The patent of publication No. CN119517980A proposes a high tap density lithium nickel manganese oxide positive electrode material, a preparation method and a lithium ion battery, a dual-particle-diameter mixed material is prepared by adopting a spray pyrolysis method, the core is focused to have high tap density, the upper limit of the par