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CN-122025619-A - Multiphase layered oxide positive electrode material and preparation method and application thereof

CN122025619ACN 122025619 ACN122025619 ACN 122025619ACN-122025619-A

Abstract

The invention provides a multiphase layered oxide positive electrode material, a preparation method and application thereof, wherein the multiphase layered oxide material is Na x MO 2 , x is more than or equal to 0.6 and less than or equal to 0.8, M comprises Ni and Mn, and the phase structure of Na x MO 2 comprises a P2 phase, a P3 phase and an O3 phase. The preparation method provided by the invention is simple and controllable, does not need to be doped with harmful elements, is suitable for large-scale production, and can effectively reduce the production cost.

Inventors

  • WEN YANLIANG
  • ZHAO YUZE
  • LIU DEXIN
  • ZHANG CHENXI
  • HONG MINGZI
  • WEI FEI

Assignees

  • 鄂尔多斯实验室

Dates

Publication Date
20260512
Application Date
20260209

Claims (10)

  1. 1. The multiphase layered oxide positive electrode material is characterized in that the multiphase layered oxide material is Na x MO 2 , x is more than or equal to 0.6 and less than or equal to 0.8, M comprises Ni and Mn, and the phase structure of Na x MO 2 comprises a P2 phase, a P3 phase and an O3 phase.
  2. 2. The multi-phase layered oxide cathode material of claim 1, wherein M further comprises any one or a combination of at least two of Cu, ti, sn, fe or Zn.
  3. 3. The multi-phase layered oxide cathode material of claim 1 or 2, wherein the weighted average ion radius of M is 0.583 a to 0.637 a.
  4. 4. The multi-phase layered oxide cathode material according to any one of claims 1-3, wherein the Na x MO 2 does not include an O'3 phase; Preferably, in all phase structures of the Na x MO 2 , the sum of mass ratios of the P2 phase, the P3 phase and the O3 phase is more than or equal to 99 percent; Preferably, the mass ratio of the P3 phase to the P2 phase to the O3 phase is (40-60): (25-50): (10-18).
  5. 5. A method for producing the multi-phase layered oxide cathode material according to any one of claims 1 to 4, comprising: s1, mixing a metal salt solution and a precipitator, and obtaining a precursor after precipitation reaction, wherein the metal salt solution comprises nickel salt and manganese salt; S2, mixing the precursor of the S1 with a sodium source, and performing calcination treatment in an air atmosphere to obtain the multiphase layered oxide cathode material, wherein the final cut-off temperature of the calcination treatment is 980-1020 ℃.
  6. 6. The method according to claim 5, wherein the metal salt solution of S1 comprises a metal salt and a solvent, the metal salt comprising a metal sulfate and/or a metal nitrate, preferably a metal sulfate; Preferably, the precipitant of S1 comprises an oxalic acid solution; preferably, the concentration of the oxalic acid solution is 2.0 mol/L-3.5 mol/L; Preferably, the temperature of the precipitation reaction in the step S1 is 65-85 ℃ and the time is 1-3 h.
  7. 7. The method of claim 5 or 6, wherein the sodium source of S2 comprises any one or a combination of at least two of sodium carbonate, sodium hydroxide or sodium bicarbonate, preferably sodium carbonate; preferably, the addition amount of the sodium source in the S2 is 104-106 wt.% of the theoretical addition amount.
  8. 8. The method according to any one of claims 5 to 7, wherein the calcination treatment of S2 comprises sequentially performing a first calcination and a second calcination; Preferably, the cut-off temperature of the first calcination is 400-500 ℃, and the heat preservation time is 4-6 hours; preferably, the cut-off temperature of the second calcination is 980 ℃ to 1020 ℃, and the heat preservation time is 14h to 16h.
  9. 9. The method according to any one of claims 5 to 8, wherein after the calcination treatment of S2, the calcined product is sequentially cooled and ground to obtain the multi-phase layered oxide cathode material; preferably, the grinding is carried out to 180-220 meshes.
  10. 10. Use of a multi-phase layered oxide cathode material according to any one of claims 1-4 in a sodium ion battery cathode.

Description

Multiphase layered oxide positive electrode material and preparation method and application thereof Technical Field The invention belongs to the technical field of sodium ion battery anode materials, and relates to a multiphase layered oxide anode material, a preparation method and application thereof. Background With the rapid development of renewable energy sources, the need for efficient energy storage systems is becoming increasingly stringent. Although lithium ion batteries are widely used, the scarcity and maldistribution of lithium resources limit their use in large-scale energy storage applications. Sodium ion batteries become a potential supplement or even alternative because of abundant sodium resources, low cost and similar working principles to lithium ion batteries. The positive electrode material is a key component that determines the performance of the sodium ion battery. The layered oxide has the characteristics of high ionic conductivity, high diffusion speed, high specific capacity and the like, and becomes a research hot spot of the positive electrode material of the sodium ion battery. However, the conventional layered oxide has structural diversity (such as P2, O3, P3 phases), and a single structure is prone to generate harmful phase change in the charge and discharge process, resulting in problems of poor cycle stability, poor rate performance, and the like. For example, pure O3 phase material is prepared by increasing Mn 4+ duty cycle (ion radius to 0.53A) to increase sodium content and initial capacity, and pure P2 phase material is prepared by increasing Ni 2+ duty cycle (ion radius to 0.69A) to optimize rate capability. However, the scheme has the inherent defects of low pure P2 phase capacity and insufficient cycle stability, and poor pure O3 phase multiplying power performance, and is easy to generate harmful phase change in the charge and discharge process to cause structural collapse. In the prior art, the performance optimization for layered oxides has mainly focused on doping modification or simple recombination in an attempt to improve the drawbacks of single phase structures, for example, by forming a P2/O3 dual phase structure by simple recombination or doping, in an attempt to combine some of the advantages of both. However, the existing scheme lacks controllability in the formation of a dual-phase structure, the phase content ratio cannot be accurately regulated and controlled, and an effective inter-phase synergistic effect is not formed, so that the performance improvement is limited. Or the phase transition is suppressed by introducing a hetero element (such as Mg, al, etc.), but the doping element does not generally participate in the electrochemical reaction, resulting in capacity sacrifice, and it is difficult to improve both the rate performance and the cycle stability. The method can not fundamentally solve the problem that the high capacity, the high multiplying power and the high stability are difficult to consider, 1, the single-phase structure is difficult to meet the requirements of high capacity, high stability and rapid ion diffusion, 2, the formation mechanism of the multiphase structure is ambiguous, a controllable preparation method is lacked, 3, the influence of the phase content on the electrochemical performance is unquantized, and the material performance is difficult to accurately optimize. Therefore, the development of the sodium ion battery anode material which has excellent comprehensive performance and controllable preparation has important significance. Disclosure of Invention Aiming at the defects existing in the prior art, the invention aims to provide a multiphase layered oxide positive electrode material, and a preparation method and application thereof. According to the invention, by regulating and controlling the multiphase structure and the phase content, the harmful phase change in the charge and discharge process is inhibited by utilizing the synergistic effect (such as the structure constraint effect) of different phases, and the cycle stability and the multiplying power performance of the material are obviously improved; in addition, the preparation method provided by the invention is simple and controllable, does not need to be doped with harmful elements, is suitable for large-scale production, and can effectively reduce the production cost. In order to achieve the aim of the invention, the invention adopts the following technical scheme: In a first aspect, the invention provides a multiphase layered oxide positive electrode material, wherein the multiphase layered oxide positive electrode material is Na xMO2, x is more than or equal to 0.6 and less than or equal to 0.8, M comprises Ni and Mn, and the phase structure of Na xMO2 comprises a P2 phase, a P3 phase and an O3 phase. For example, x is 0.6, 0.62, 0.68, 0.72, 0.75, 0.78, or 0.8, etc. Fig. 1 shows layered crystal structures of P2 phase (hexagonal stack, uniform Na + layer s