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CN-121983559-A - Interface modified lithium manganate positive electrode material and preparation method thereof

CN121983559ACN 121983559 ACN121983559 ACN 121983559ACN-121983559-A

Abstract

The invention discloses an interface modified lithium manganate positive electrode material and a preparation method thereof, and belongs to the technical field of positive electrode materials. The interface modified lithium manganate positive electrode material comprises a LiMn 2 O 4 inner core, a W-and M-doped lithium manganate first coating layer coated on at least part of the surface of the inner core, and a M 2 WO 6‑z N z second coating layer coated on at least part of the surface of the first coating layer. The two coating layers form a remarkable synergistic effect, S/Se doping of the second coating layer is matched with that of the first coating layer M, W, the overall structural stability of the coating layer is enhanced, cracking and falling in long-term circulation of the coating layer are effectively restrained, the long-acting performance of protecting a lithium manganate matrix interface is guaranteed, meanwhile, lattice defects introduced by S/Se doping are synergistic and complementary with lattice matching advantages of the first coating layer, the migration kinetic rate of lithium ions is optimized, and the electronic conductivity and interface stability of the material are synchronously 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 interface modified lithium manganate positive electrode material is characterized by comprising a LiMn 2 O 4 inner core, a W-and M-doped LiMn 2 O 4 first coating layer coated on at least part of the surface of the inner core and a second coating layer coated on at least part of the surface M 2 WO 6-z N z of the first coating layer, wherein M is one or more of Sb, bi, cr and Fe, N is one or two of S and Se, and z is 0.01 percent < z is less than or equal to 1 percent.
  2. 2. The interface-modified lithium manganate cathode material of claim 1, wherein N is selected from two of S and Se.
  3. 3. The method for preparing an interface-modified lithium manganate positive electrode material according to claim 1 or 2, characterized by comprising the steps of: S1, mixing a tungsten source and an M source, placing the mixture in a sintering furnace for first-stage electric field sintering, and after sintering, introducing N source gas into the sintering furnace for second-stage electric field sintering to obtain a coating material; s2, mixing the coating material with LiMn 2 O 4 , and performing electric field sintering under an inert atmosphere to obtain the interface modified lithium manganate anode material.
  4. 4. The method for preparing an interface-modified lithium manganate positive electrode material according to claim 3, wherein in the step S1, the tungsten source is one or more of tungsten trioxide, ammonium tungstate and ammonium paratungstate; and/or M source is one or more of oxide, acetate and nitrate of M; And/or the ratio of the number of moles of W in the tungsten source to the number of moles of M in the M source is 1 (2-2.1); and/or N source gas is one or two of H 2 S and H 2 Se; and/or the ratio of the number of moles of N in the N source gas to the number of moles of W in the tungsten source is (0.01-2): 100.
  5. 5. The method for preparing an interface-modified lithium manganate positive electrode material according to claim 3, wherein in the step S1, the electric field strength of the first-stage electric field sintering or the second-stage electric field sintering is 200 to 400v/cm independently; And/or the temperature of the first section electric field sintering or the first section electric field sintering is 600-900 ℃ independently; and/or the time of the electric field sintering in the first section is 1-8 h, and the time of the electric field sintering in the second section is 0.1-0.3 h.
  6. 6. The method for preparing an interface-modified lithium manganate positive electrode material according to claim 3, wherein in the step S2, the mass of the coating material is 1-10% of the mass of LiMn 2 O 4 .
  7. 7. The method for preparing the interface-modified lithium manganate positive electrode material according to claim 3, wherein in the step S2, the inert atmosphere is nitrogen atmosphere or argon atmosphere, the electric field strength of electric field sintering is 200-300V/cm, the electric field sintering temperature is 450-550 ℃, and the electric field sintering time is 0.1-0.5 h.
  8. 8. The method for preparing the interface-modified lithium manganate positive electrode material according to claim 3, wherein in the step S2, the preparation method of the LiMn 2 O 4 comprises the steps of fully mixing manganese dioxide and lithium carbonate, and then performing pressure sintering to obtain LiMn 2 O 4 .
  9. 9. The preparation method of the interface-modified lithium manganate positive electrode material according to claim 8, wherein the molar ratio of manganese dioxide to lithium carbonate is 1 (0.25-0.253), the pressure of pressure sintering is 0.01-0.1 MPa, the temperature of pressure sintering is 700-850 ℃, and the pressure sintering time is 5-12 h.
  10. 10. A battery, characterized by comprising the interface-modified lithium manganate positive electrode material according to claim 1 or 2, or the interface-modified lithium manganate positive electrode material prepared by the preparation method according to any one of claims 3 to 9.

Description

Interface modified lithium manganate positive electrode material and preparation method thereof Technical Field The invention belongs to the technical field of positive electrode materials, and particularly relates to an interface modified lithium manganate positive electrode material and a preparation method thereof. Background The lithium ion battery is widely applied to various energy storage scenes, and the performance of the lithium ion battery is greatly dependent on the positive electrode material. Spinel type lithium manganate (LiMn 2O4) has the advantages of rich resources, low cost, environmental friendliness, good safety and outstanding multiplying power performance, becomes an important research direction of the power battery anode material, and has good commercialization potential. The spinel LiMn 2O4 has a three-dimensional tunnel structure, provides a convenient channel for reversible deintercalation of lithium ions, and has a theoretical specific capacity of 148mAh/g. In practical application, the electrochemical performance of LiMn 2O4 is limited by two major problems, namely frequent interface side reaction, reaction such as hydrofluoric acid generation, manganese dissolution and abnormal growth of CEI film caused by contact of an anode with electrolyte during charge and discharge, damage of lattice structure, degradation of battery capacity and cycle performance, poor conductivity, low material electron conductivity and ion mobility, high electron transmission resistance, influence on battery multiplying power performance and charge and discharge efficiency, and incapability of meeting high power requirements. The existing modification schemes, such as surface coating, ion doping, carbon-based compounding and the like, can only singly improve interface stability or conductivity, are difficult to realize cooperative promotion, and cannot fundamentally solve performance bottlenecks. Therefore, the technical scheme capable of simultaneously reducing the side reaction of the interface and improving the conductivity is developed, the cooperative optimization of the interface and the conductivity is realized, and the method has important significance for promoting the large-scale industrialized application of the LiMn 2O4. Disclosure of Invention Aiming at the problems, the invention aims to provide an interface modified lithium manganate positive electrode material and a preparation method thereof. In a first aspect, the invention provides an interface-modified lithium manganate positive electrode material, which comprises a LiMn 2O4 inner core, a W-and M-doped LiMn 2O4 first coating layer coated on at least part of the surface of the inner core, and a M 2WO6-zNz second coating layer coated on at least part of the surface of the first coating layer, wherein M is one or more of Sb, bi, cr and Fe, N is one or two of S and Se, and z is 0.01% < z less than or equal to 1%. Preferably, the N is selected from two of S and Se. In a second aspect, the invention provides an interface-modified lithium manganate positive electrode material, comprising the following steps: s1, mixing a tungsten source and an M source, placing the mixture in a sintering furnace for first-stage electric field sintering, and after sintering, introducing N source gas into the sintering furnace for second-stage electric field sintering to obtain the coating material. S2, mixing the coating material with LiMn 2O4, and performing electric field sintering under an inert atmosphere to obtain the interface modified lithium manganate anode material. Preferably, in step S1, the tungsten source is one or more of tungsten trioxide, ammonium tungstate, and ammonium paratungstate. Preferably, in step S1, the M source is one or more of an oxide, an acetate, and a nitrate of M. Preferably, in step S1, the ratio of the number of moles of W in the tungsten source to the number of moles of M in the M source is 1 (2 to 2.1). Preferably, in the step S1, the N source gas is one or two of H 2 S and H 2 Se, and the ratio of the number of moles of N in the N source gas to the number of moles of W in the tungsten source is (0.01-2): 100. Preferably, in the step S1, the electric field strength of the first-stage electric field sintering or the second-stage electric field sintering is 200-400V/cm independently. Preferably, in step S1, the temperature of the first stage electric field sintering or the second stage electric field sintering is 600 to 900 ℃ independently. Preferably, in the step S1, the electric field sintering time of the first section is 1-8 h, and the electric field sintering time of the second section is 0.1-0.3 h. Preferably, in step S2, the mass of the coating material is 1-10% of the mass of LiMn 2O4. Preferably, in the step S2, the inert atmosphere is nitrogen atmosphere or argon atmosphere, the electric field strength of electric field sintering is 200-300V/cm, the electric field sintering temperature is 450-550 ℃, and the electri