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CN-122025614-A - High-air-stability ternary cathode material based on two-step plasma technology and preparation method and application thereof

CN122025614ACN 122025614 ACN122025614 ACN 122025614ACN-122025614-A

Abstract

The invention belongs to the technical field of positive electrode materials, and relates to a high-air-stability ternary positive electrode material based on a two-step plasma technology, and a preparation method and application thereof. And sintering the ternary cathode material and a zirconium source in an oxygen plasma atmosphere under normal pressure, so that efficient and uniform doping of Zr element into a bulk lattice of the material is promoted, the crystallization process of the material is synchronously completed, and bulk strengthening of a lattice structure is realized. Subsequently, the obtained Zr-doped ternary material is placed in a vacuum environment, and a fluorine source gas such as nitrogen trifluoride is introduced and excited to generate plasma for surface lithium fluoride (LiF) cladding. The invention realizes the cooperative modification of bulk phase doping and surface coating by the two-step plasma technology. After the prepared ternary positive electrode material is exposed to humid air, the capacity retention rate, the cycle life and the multiplying power performance of the ternary positive electrode material are remarkably improved, and the performance is far superior to that of an unmodified material and a single modified sample. Has wide industrialization application prospect.

Inventors

  • XIA XINHUI
  • Cai Hongning
  • XIANG JIAYUAN
  • XIA YANG
  • SHEN SHENGHUI
  • ZHANG YONGQI
  • ZHANG JUN
  • FANG RUYI
  • ZHANG WENKUI

Assignees

  • 浙江工业大学

Dates

Publication Date
20260512
Application Date
20260413

Claims (10)

  1. 1. The preparation method of the ternary positive electrode material with high air stability based on the two-step plasma technology is characterized by comprising the following steps of: (1) Placing the mixture of the ternary anode material and the zirconium source in a plasma sintering device, introducing oxygen-enriched atmosphere, and sintering to obtain a zirconium-doped ternary anode material; (2) Transferring the doped ternary anode material into a vacuum plasma treatment device, introducing fluorine source gas, and performing plasma treatment to obtain the ternary anode material with the surface in-situ generated lithium fluoride-based coating layer.
  2. 2. The preparation method of the ternary positive electrode material with high air stability based on the two-step plasma technology, which is disclosed in claim 1, is characterized in that in the step (1), the chemical formula of the ternary positive electrode material is LiNi x Co y Mn z O 2 , wherein x+y+z= 1,0.6 is less than or equal to x <1,0< y is less than or equal to 0.2, and 0< z is less than or equal to 0.2.
  3. 3. The preparation method of the ternary cathode material with high air stability based on the two-step plasma technology, which is characterized in that in the step (1), the ternary cathode material and a zirconium source are mixed by adopting wet mixing to obtain a mixture, the wet mixing step comprises the steps of mixing the ternary cathode material and the zirconium source in a solvent by a wet method, stirring the mixture under a heating condition until the solvent is completely volatilized, and then drying the obtained mixture; and/or the ethanol solvent amount is 30-100 ml, the heating and stirring temperature is 60-100 ℃, and the stirring speed is 400-800 r/min; And/or the ethanol solvent amount is 60 ml, the heating and stirring temperature is 80 ℃, and the stirring rotating speed is 650 r/min.
  4. 4. The method for preparing the ternary cathode material with high air stability based on the two-step plasma technology, which is characterized in that in the step (1), a zirconium source comprises at least one of zirconium oxychloride, zirconium nitrate, zirconium acetylacetonate, zirconium oxychloride and zirconium silicate; and/or the doping amount of the zirconium source is 0.5-2at% based on the atomic percentage of zirconium element in the total metal molar amount of nickel, cobalt, manganese and zirconium; And/or the oxygen volume ratio in the oxygen-enriched atmosphere is not less than 80%, and the flow rate of the oxygen-enriched atmosphere is 50-200 sccm based on the flow rate of oxygen; And/or sintering at 500-750 ℃ for 2-5 hours.
  5. 5. The preparation method of the ternary positive electrode material with high air stability based on the two-step plasma technology, which is characterized in that the zirconium source is zirconium nitrate; and/or the doping amount of the zirconium source is 1 at percent based on the atomic percent of zirconium element accounting for the total metal mole amount of nickel, cobalt, manganese and zirconium; and/or the oxygen-enriched atmosphere is oxygen, and the flow rate of the oxygen is 100 sccm; and/or sintering at 600 ℃ for 3 hours.
  6. 6. The method for preparing the ternary positive electrode material with high air stability based on the two-step plasma technology, which is characterized in that the fluorine source gas in the step (2) is at least one selected from nitrogen trifluoride, carbon tetrafluoride, carbonyl fluoride, hexafluorobutadiene and freon; And/or the plasma treatment condition comprises that the reaction temperature is 200-500 ℃, the reaction time is 4-10 min, and the power of the plasma device is 200-550W.
  7. 7. The method for preparing the ternary positive electrode material with high air stability based on the two-step plasma technology, which is disclosed in claim 6, is characterized in that the fluorine source gas is nitrogen trifluoride, and/or the plasma treatment conditions comprise a reaction temperature of 300 ℃, a reaction time of 6 min and a device power of 300W.
  8. 8. The preparation method of the ternary positive electrode material with high air stability based on the two-step plasma technology, which is disclosed in claim 1, is characterized in that the thickness of the surface coating layer of the ternary positive electrode material is 3-10 nm.
  9. 9. A ternary positive electrode material with high air stability based on a two-step plasma technology, which is prepared by the preparation method according to any one of claims 1-8.
  10. 10. Use of the high air stability ternary cathode material based on the two-step plasma technology according to claim 9 in the field of batteries.

Description

High-air-stability ternary cathode material based on two-step plasma technology and preparation method and application thereof Technical Field The invention relates to a high-air-stability ternary positive electrode material based on a two-step plasma technology, and a preparation method and application thereof, and belongs to the technical field of positive electrode materials of lithium ion batteries. Background Lithium ion batteries are used as a new generation of green high-energy chemical power supply and are widely applied to the fields of consumer electronics, electric automobiles and large-scale energy storage. The layered ternary cathode material LiNi xCoyMnZO2 (NCM) is regarded as a key cathode material for realizing long endurance mileage of an electric vehicle by virtue of its high specific capacity and high energy density. Since Ni 3+/4+ has a strong oxidizing property, its bond energy with O 2- is weak, resulting in that lattice oxygen is easily oxidized under electrochemical or environmental conditions and even precipitates as oxygen. This intrinsic thermodynamic instability is the root cause of the sensitivity of materials to ambient atmospheres (e.g., H 2 O and CO 2). During the synthesis and storage of the material, the unstable lattice structure promotes lithium ions to migrate to the particle surface and react with water vapor and carbon dioxide in the air to generate residual alkali species such as Li 2CO3 and LiOH. This process not only consumes active lithium sources, resulting in irreversible capacity loss, but also induces structural defects in the near-surface region. With the continuous loss of lithium and the reconstruction of the valence state of transition metal, the lamellar structure of the surface layer of the material is subjected to irreversible phase transformation and is converted into an electrochemically inert rock salt phase (such as NiO). The rock salt phase serves as a layer of compact insulating barrier, so that diffusion kinetics of lithium ions at an interface is seriously hindered, interface impedance is obviously improved, and therefore, the rate capability of a material is deteriorated, and the rock salt phase becomes a core cause of capacity continuous attenuation and voltage polarization in a circulation process. Therefore, the ternary positive electrode material is required to rely on strict low-humidity environment control in the production, storage and electrode preparation processes, and the process complexity and the manufacturing cost are greatly increased. The key point is to enhance the stability of the lattice structure, in particular to strengthen the binding capacity of lattice oxygen, so as to inhibit the occurrence of the chain degradation reaction from the source. In order to improve the electrochemical performance and stability of the high-nickel ternary material, two modification strategies of bulk doping and surface cladding are commonly adopted in the industry, but the paths of the prior art have obvious defects. For example, CN202211726223.7 authorizes a preparation method of a zirconium-doped ternary cathode material, the ternary cathode material and application thereof, and the preparation method comprises the steps of S1, preparing a first precursor by adopting a soluble nickel salt, a soluble cobalt salt and a soluble salt containing M element through a first coprecipitation reaction according to the stoichiometric ratio of each element in the zirconium-doped ternary cathode material, wherein the first precursor contains nickel element, cobalt element and manganese element, the stoichiometric ratio in the first precursor is Ni: co: mn=8:1:1, S2, depositing zirconium dioxide on the surface of the first precursor through a second coprecipitation reaction to obtain a second precursor, the particle size of the zirconium dioxide is less than or equal to 100 nm, S3, mixing the second precursor with a lithium source according to the stoichiometric ratio of each element in the zirconium-doped ternary cathode material, heating to 480 ℃ at a temperature rising rate of 5 ℃ per min, then heating to be 5 ℃ at a temperature rising rate of 5 ℃ for 5 hours, and then heating to be 800 ℃ at a temperature rising rate of 5 ℃ for 20 ℃ to obtain the zirconium-doped ternary cathode material, and preparing the zirconium-doped ternary cathode material at a temperature of 0.20 ℃ through a second coprecipitation reaction. The technical core of the method is that the single-dimensional bulk zirconium doping is realized by a complex multi-step wet process and long-time high-temperature sintering (750-900 ℃), so that the method has the advantages of high energy consumption, long process, easiness in introducing impurities and complete failure in solving the key industrialization bottleneck of poor air stability caused by residual lithium on the surface of the high-nickel ternary material. And requires sintering at 750-900 ℃ for a long time (12-24 hours), and has ex