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CN-121983560-A - Composite modified lithium manganate positive electrode material and preparation method and application thereof

CN121983560ACN 121983560 ACN121983560 ACN 121983560ACN-121983560-A

Abstract

The invention belongs to the field of battery materials, and particularly discloses a composite modified lithium manganate positive electrode material, a preparation method and application thereof, wherein the positive electrode material comprises a core and a coating layer, the coating layer is coated on at least part of the surface of the core, the core is a LiMn 2 O 4 material, the coating layer comprises a LiM x Mn 2‑x O 4 material and a ZnMn 2 O 4 material, wherein M is any one or more than two of Zn, fe and Ni, and x is more than or equal to 0.1 and less than or equal to 0.4. The composite coating structure provided by the invention forms a synergistic system of nuclear layer ion transmission, coating layer structural support and electron conduction, the structural stability at high multiplying power is ensured by the coating layer, the electron transmission efficiency is improved, meanwhile, the coating layer material does not cause the increase of lithium ion transmission resistance, the capacity loss and polarization are reduced, and the electrochemical performance of the battery at high multiplying power is further improved.

Inventors

  • ZHANG YINGCHUN
  • LUO KUN
  • Zhou Qiangrong

Assignees

  • 四川长宏新能源技术有限公司

Dates

Publication Date
20260505
Application Date
20260403

Claims (10)

  1. 1. The composite modified lithium manganate positive electrode material is characterized by comprising a core and a coating layer, wherein the coating layer is coated on at least part of the surface of the core, the core is made of LiMn 2 O 4 material, the coating layer comprises LiM x Mn 2-x O 4 material and ZnMn 2 O 4 material, M is any one or more than two of Zn, fe and Ni, and x is more than or equal to 0.1 and less than or equal to 0.4.
  2. 2. The composite modified lithium manganate positive electrode material according to claim 1, wherein the particle surface of the composite modified lithium manganate positive electrode material is in a polyhedral shape, and the particle size of the composite modified lithium manganate positive electrode material is 100-300 nm.
  3. 3. A preparation method of a composite modified lithium manganate positive electrode material is characterized by comprising the steps of ball milling and mixing a LiMn 2 O 4 material, a LiM x Mn 2-x O 4 material and a ZnMn 2 O 4 material, and sintering in air or oxygen-containing atmosphere, wherein M is one or more than two of Zn, fe and Ni, and x is more than or equal to 0.1 and less than or equal to 0.4.
  4. 4. The method for preparing the composite modified lithium manganate positive electrode material according to claim 3, wherein the ball milling speed is 300-1000r/min, the ball milling time is 0.5-5h, the sintering temperature is 500-700 ℃ and the sintering time is 0.5-2h.
  5. 5. The method for preparing the composite modified lithium manganate positive electrode material according to claim 3 or 4, wherein the mass ratio of the LiMn 2 O 4 material, the LiM x Mn 2-x O 4 material and the ZnMn 2 O 4 material is 1 (0.01-0.04): 0.01-0.04).
  6. 6. The method for preparing the composite modified lithium manganate positive electrode material according to claim 3, wherein the preparation method of the LiM x Mn 2-x O 4 material comprises the steps of ball milling and mixing manganese dioxide, metal M oxide and a lithium source, and sintering under air or oxygen-containing atmosphere.
  7. 7. The preparation method of the composite modified lithium manganate positive electrode material according to claim 6, wherein the ball milling speed is 300-1000r/min, the ball milling time is 0.5-5h, one or more of zinc oxide, ferrous oxide and nickel oxide of metal M oxide, one or more of lithium hydroxide, lithium acetate and lithium nitrate are adopted as a lithium source, the stoichiometric ratio of M in manganese dioxide and metal M oxide to LiM x Mn 2-x O 4 material is consistent, the molar ratio of lithium in lithium source is 1-1.06 times of the stoichiometric ratio of LiM x Mn 2-x O 4 material, the sintering temperature is 880-1000 ℃, and the sintering time is 8-16h.
  8. 8. The method for preparing the composite modified lithium manganate positive electrode material according to claim 3, wherein the preparation method of the ZnMn 2 O 4 material comprises the steps of ball milling, mixing manganese dioxide and a zinc source, and sintering in air or oxygen-containing atmosphere.
  9. 9. The preparation method of the composite modified lithium manganate positive electrode material of claim 8, which is characterized in that the ball milling rotating speed is 300-1000r/min, the ball milling time is 0.5-5h, the zinc source is any one or more than two of zinc oxide, zinc acetate and zinc nitrate, the stoichiometric ratio of manganese in manganese dioxide and zinc in the zinc source to manganese dioxide and zinc source is consistent, the sintering temperature is 700-900 ℃, and the sintering time is 4-12h.
  10. 10. A battery characterized by comprising the composite modified lithium manganate positive electrode material according to any one of claims 1 to 2 or the composite modified lithium manganate positive electrode material prepared by the preparation method according to any one of claims 3 to 9.

Description

Composite modified lithium manganate positive electrode material and preparation method and application thereof Technical Field The invention belongs to the field of battery materials, and relates to a positive electrode material, in particular to a composite modified lithium manganate positive electrode material, and a preparation method and application thereof. Background The LiMn 2O4 anode material is one of the anode materials of the lithium ion battery with optimal development potential due to the advantages of low cost, high energy density, no pollution, good safety, rich resources and the like. However, the rate performance of LiMn 2O4 is limited by the bulk and interfacial transmission rate of lithium ions, and the core reasons are that the bulk diffusion is slow, the interfacial migration resistance is large, and the requirement of high current on rapid ion transmission under high rate cannot be matched. In bulk terms, the spinel structure of LiMn 2O4 provides a diffusion path for lithium ions of 8a→16c→8a, but the channel has a small effective cross section, and electrostatic repulsion of Mn 3+/Mn4+ in the lattice increases the Li + transport energy barrier, resulting in a Li + phase of LiMn 2O4 that diffuses much slower than a positive electrode material such as LiCoO 2. Meanwhile, particle cracks caused by Li + intercalation/deintercalation in circulation can cut off a diffusion channel, and lattice parameters caused by phase change are changed dramatically, so that channel space can be further compressed, and the bottleneck of bulk phase transmission is aggravated. From the interface, electrolyte decomposition in circulation can form an SEI film with poor ion conductivity on the surface of LiMn 2O4, the film can thicken along with the circulation and block micropores, the migration path of Li + is prolonged, the resistance is increased, the large current can accelerate the volume deformation of particles under high multiplying power, the interface between the particles and a conductive agent and the adhesive is peeled off, a contact gap is formed, the ion transmission path is cut off, and meanwhile, the excessive decomposition of the electrolyte is aggravated due to local high current density, more impedance substances are generated, and the migration environment of the interface is worsened. Under a high-rate scene, the requirement of embedding/deintercalating a large amount of Li + in a short time forms supply-demand unbalance with low transmission efficiency of a bulk phase and an interface, the Li + on the surface of the positive electrode is excessively consumed due to slow transmission during charging, the lithium removal amount is reduced due to rapid voltage rise to a cut-off voltage, the Li + on the negative electrode side can not reach an active site in time during discharging, the Li + on the negative electrode side can only be consumed through side reaction, and the capacity is rapidly reduced and the voltage polarization is aggravated finally. That is, the transmission efficiency of two key links of bulk diffusion and interface migration of LiMn 2O4 cannot match the requirement of high current on rapid ion transport at high magnification. Disclosure of Invention In order to overcome the defects and shortcomings of the prior art, the invention provides a composite modified lithium manganate positive electrode material, a preparation method of the composite modified lithium manganate positive electrode material and a battery. In a first aspect, the invention provides a composite modified lithium manganate positive electrode material, which comprises a core and a coating layer, wherein the coating layer is coated on at least part of the surface of the core; The core is made of LiMn 2O4 material, and the coating layer comprises LiM xMn2-xO4 material and ZnMn 2O4 material, wherein M is any one or more than two of Zn, fe and Ni, and x is more than or equal to 0.1 and less than or equal to 0.4. Preferably, the particle surface of the composite modified lithium manganate positive electrode material is in a polyhedral shape. Preferably, the particle size of the composite modified lithium manganate positive electrode material is 100-300 nm. The second aspect of the invention provides a preparation method of a composite modified lithium manganate positive electrode material, which comprises the steps of ball milling and mixing a LiMn 2O4 material, a LiM xMn2-xO4 material and a ZnMn 2O4 material, and sintering in air or an oxygen-containing atmosphere, wherein M is one or more than two of Zn, fe and Ni, and x is more than or equal to 0.1 and less than or equal to 0.4. Preferably, the ball milling rotating speed is 300-1000r/min, and the ball milling time is 0.5-5h. Preferably, the mass ratio of the LiMn 2O4 material, the LiM xMn2-xO4 material and the ZnMn 2O4 material is 1 (0.01-0.04): 0.01-0.04. Preferably, the sintering temperature is 500-700 ℃ and the sintering time is 0.5-2h. Preferably, t