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CN-121983561-A - Interface modified lithium manganate positive electrode material, preparation method thereof and battery

CN121983561ACN 121983561 ACN121983561 ACN 121983561ACN-121983561-A

Abstract

The invention belongs to the field of lithium ion battery materials, and particularly discloses an interface modified lithium manganate positive electrode material, a preparation method thereof and a battery, wherein the interface modified lithium manganate positive electrode material comprises a core, a first coating layer and a second coating layer, the first coating layer is coated on at least part of the surface of the core, and the second coating layer is coated on at least part of the surface of particles formed by the core and the first coating layer; the core is made of LiMn 2 O 4 material, the first coating layer is made of metal oxide, and the second coating layer is made of a mixed material of carbon and a fast ion conductor. The interface stability and the multiplying power performance of the material can be effectively improved through a multidimensional interface modification strategy.

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 (9)

  1. 1. The interface modified lithium manganate positive electrode material is characterized by comprising a core, a first coating layer and a second coating layer, wherein the first coating layer is coated on at least part of the surface of the core, and the second coating layer is coated on at least part of the surface of particles formed by the core and the first coating layer; The core is a LiMn 2 O 4 material; The first coating layer is metal oxide; the second coating layer is a mixed material of carbon and a fast ion conductor.
  2. 2. The interface-modified lithium manganate positive electrode material according to claim 1, wherein the first coating layer is one or more of Al 2 O 3 , mgO and CuO, and the fast ion conductor is one or more of LiAlO 2 、Li 3 Zr 2 (PO 4 ) 3 .
  3. 3. The interface-modified lithium manganate cathode material according to claim 1 or 2, wherein the particle size of the interface-modified lithium manganate cathode material is 100-400nm.
  4. 4. The preparation method of the interface modified lithium manganate anode material is characterized by comprising the following steps of: Step 1, mixing a LiMn 2 O 4 material and metal salt, and calcining in an air atmosphere to obtain an intermediate product; and 2, mixing the intermediate product, the fast ion conductor, the polymer and the solvent to obtain slurry, drying the slurry, and calcining the slurry in a protective atmosphere to obtain the high-voltage cable.
  5. 5. The method for preparing an interface-modified lithium manganate positive electrode material according to claim 4, wherein in the step 1, the metal salt is one or more than two of Al(NO 3 ) 3 、Mg(NO 3 ) 2 、Cu(NO 3 ) 2 、Al(CH 3 COO) 3 、Mg(CH 3 COO) 2 、Cu(CH 3 COO) 2 .
  6. 6. The method for preparing the interface-modified lithium manganate positive electrode material according to claim 4 or 5, wherein in the step 1, the molar ratio of the LiMn 2 O 4 material to the metal salt is 1:0.01-0.05, the calcination temperature is 300-400 ℃, and the calcination time is 0.5-2 hours.
  7. 7. The preparation method of the interface modified lithium manganate positive electrode material according to claim 4, which is characterized in that in the step 2, the fast ion conductor is any one or two of LiAlO 2 、Li 3 Zr 2 (PO 4 ) 3 , the polymer is any one or two of PVDF and PAM, the solvent is any one or more of NMP solution, acetone and ethanol, and the mass ratio of the intermediate product to the fast ion conductor to the polymer is 1: (0.01-0.06): (0.01-0.05).
  8. 8. The method for preparing an interface-modified lithium manganate cathode material according to claim 4 or 7, wherein in the step 2, the solid-to-liquid ratio of the slurry is 1 g:10-40 mL, the drying time is 3-20h, the drying temperature is 50-90 ℃, the calcining temperature is 400-600 ℃ and the calcining time is 0.5-2h.
  9. 9. A battery characterized by comprising the interface-modified lithium manganate positive electrode material according to any one of claims 1 to 3 or the interface-modified lithium manganate positive electrode material prepared by the preparation method according to any one of claims 4 to 8.

Description

Interface modified lithium manganate positive electrode material, preparation method thereof and battery Technical Field The invention belongs to the field of lithium ion battery materials, relates to a positive electrode material, and in particular relates to an interface modified lithium manganate positive electrode material, a preparation method thereof and a battery. Background The LiMn 2O4 material has important roles in the field of lithium ion battery anode materials by virtue of the outstanding advantages of high power density, stable working voltage, rich manganese resource reserves, low cost, environmental friendliness and the like, and particularly has potential application value in scenes with higher requirements on cost and safety, such as power batteries, large-scale energy storage batteries and the like. However, the inherent structural characteristics of LiMn 2O4 materials and the chemical interactions of electrode-electrolyte interfaces make them face a number of performance bottlenecks during actual charge-discharge cycles, severely restricting their commercial popularization and long-term stable application. In the charge-discharge reaction, the spinel lattice of LiMn 2O4 is subjected to periodical volume expansion along with the intercalation/deintercalation of Li +, and the repeated structural deformation can cause microcracks on the particle surface, so that the fresh active surface originally wrapped inside is exposed to electrolyte. In the electrolyte system, HF generated by the reaction of lithium salt (such as LiPF 6) and trace moisture can be subjected to disproportionation reaction with Mn 3+ on the surface of LiMn 2O4, and the generated Mn 2+ is extremely easy to dissolve in the electrolyte and migrate to the negative electrode for deposition. The continuous loss of Mn element can damage the integrity of the crystal lattice, form a large number of cation vacancies, not only block the diffusion channel of Li +, but also cause lattice distortion and even phase transformation (such as cubic phase to tetragonal phase transformation), and finally lead to material structural collapse and rapid capacity decay. The surface coating is used as a direct and effective interface modification strategy, and a protective layer is constructed on the surface of LiMn 2O4 particles, so that the direct contact between the active material and electrolyte can be physically isolated, and side reactions are inhibited. However, single type of coating often has short-circuit functions, for example, conventional oxide coatings (such as Al 2O3 and ZnO) can inhibit Mn dissolution to a certain extent, but have poor self ion conductivity and can increase Li + transmission resistance, while conductive polymer or doped spinel phase coatings can improve conductivity, but have insufficient structural stability or interfacial bonding force, coating peeling easily occurs after long-term circulation, and long-term protection of material interfaces is difficult to realize. Therefore, the single coating layer has limited comprehensive improvement effect on the circulation stability and conductivity of the LiMn 2O4, and the development of a composite coating system with interface protection, structural support and ion/electron transmission functions becomes a key direction for breaking through the performance bottleneck of the LiMn 2O4. Disclosure of Invention In order to overcome the defects and shortcomings of the prior art, the invention provides an interface modified lithium manganate positive electrode material, a preparation method of the interface modified lithium manganate positive electrode material and a battery. In a first aspect, the invention provides an interface modified lithium manganate positive electrode material, which comprises a core, a first coating layer and a second coating layer, wherein the first coating layer is coated on at least part of the surface of the core, and the second coating layer is coated on at least part of the surface of particles formed by the core and the first coating layer; The core is a LiMn 2O4 material; The first coating layer is metal oxide; the second coating layer is a mixed material of carbon and a fast ion conductor. Preferably, the first coating layer is any one or more of Al 2O3, mgO, and CuO. Preferably, the fast ion conductor is any one or two of LiAlO 2、Li3Zr2(PO4)3. Preferably, the particles of the interface-modified lithium manganate positive electrode material have a polyhedral morphology and a rough surface. Preferably, the particle size of the interface-modified lithium manganate positive electrode material is 100-400nm. In a second aspect, the invention provides a preparation method of an interface modified lithium manganate positive electrode material, which comprises the following steps: Step 1, mixing a LiMn 2O4 material and metal salt, and calcining in an air atmosphere to obtain an intermediate product; step 2, mixing the intermediate product, the fas