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CN-122000336-A - Composite modified lithium nickel manganese oxide positive electrode material and preparation method and application thereof

CN122000336ACN 122000336 ACN122000336 ACN 122000336ACN-122000336-A

Abstract

The invention provides a composite modified lithium nickel manganese oxide positive electrode material, and a preparation method and application thereof, and belongs to the technical field of electrode materials. The lithium ion diffusion channel is enlarged by doping low-valence metal in the lithium nickel manganese oxide anode material, the multiplying power performance of the anode material is improved, the lattice distortion is restrained, the structural stability is improved, the M-O bond can be enhanced by doping high-valence metal, the lattice structure is stabilized, the structural stability of the anode material is improved, the valence state of manganese can be kept stable by doping high-valence metal, side reaction is reduced, meanwhile, the lithium salt of the high-valence metal growing on the surface of the co-doped lithium nickel manganese oxide anode material in situ is taken as a shell, the lithium ion diffusion channel has the advantages of fast ion conductivity, corrosion resistance, interface stability and electrochemical performance of the anode material, the bonding stability of a cladding layer and the anode material can be improved, the service life of the cladding layer is prolonged, and the structural stability and the service life of the material under high voltage can be synergistically improved by doping elements and fast ion conductor cladding.

Inventors

  • WANG GUOQING
  • BAI ZHENHUI

Assignees

  • 山东创能新材料有限公司
  • 北京创能惠通科技有限公司

Dates

Publication Date
20260508
Application Date
20260305

Claims (10)

  1. 1. A composite modified lithium nickel manganese oxide positive electrode material comprises a co-doped lithium nickel manganese oxide positive electrode material and a fast ion conductor coated outside the co-doped lithium nickel manganese oxide positive electrode material in situ; The doping elements in the co-doped lithium nickel manganese oxide positive electrode material comprise high-valence metal and low-valence metal, wherein the high-valence metal is one or more of metal with valence of +5, and the low-valence metal is one or more of metal with valence of +1 to +4 in any valence state; the fast ion conductor is a compound with a structural formula of LiMO 3 , wherein M is a high-valence metal in the co-doped lithium nickel manganese oxide positive electrode material.
  2. 2. The composite modified lithium nickel manganese oxide positive electrode material according to claim 1, wherein the thickness of the fast ion conductor is 5-30 nm.
  3. 3. The composite modified lithium nickel manganese oxide positive electrode material according to claim 1, wherein the doping amount of the high-valence metal is 0.2-1% and the doping amount of the low-valence metal is 0.1-0.5% based on the mass of the lithium nickel manganese oxide positive electrode material in the co-doped lithium nickel manganese oxide positive electrode material.
  4. 4. The composite modified lithium nickel manganese oxide positive electrode material according to claim 1, wherein the high valence metal comprises niobium, vanadium or tantalum, and the low valence metal comprises aluminum, indium, magnesium, titanium, zirconium or iron.
  5. 5. The composite modified lithium nickel manganese oxide positive electrode material according to claim 4, wherein the high-valence metal is niobium and the low-valence metal is aluminum or magnesium.
  6. 6. The method for preparing the composite modified lithium nickel manganese oxide positive electrode material according to any one of claims 1 to 5, which is characterized by comprising the following steps: mixing an oxalic acid complex of high-valence metal, an oxide containing low-valence metal and a lithium nickel manganese oxide positive electrode material to obtain a precursor; and sintering the precursor to obtain the composite modified lithium nickel manganese oxide positive electrode material, wherein the sintering temperature is 500-700 ℃, and the heat preservation time is 3-8 hours.
  7. 7. The preparation method of claim 6, wherein the total mass of the oxalic acid complex of the high-valence metal and the oxide containing the low-valence metal is 1.5-5% of the mass of the lithium nickel manganese oxide positive electrode material.
  8. 8. The method according to claim 7, wherein the mass ratio of the oxalic acid complex of the higher metal to the oxide containing the lower metal is (1-5): 1.
  9. 9. The method of claim 6, wherein the method of mixing is ball milling.
  10. 10. The lithium ion battery positive electrode is characterized in that an active material in the lithium ion battery positive electrode is the composite modified lithium nickel manganese oxide positive electrode material according to any one of claims 1-5 or the composite modified lithium nickel manganese oxide positive electrode material prepared by the preparation method according to any one of claims 6-9.

Description

Composite modified lithium nickel manganese oxide positive electrode material and preparation method and application thereof Technical Field The invention belongs to the technical field of electrode materials, and particularly relates to a composite modified lithium nickel manganese oxide positive electrode material, and a preparation method and application thereof. Background Lithium ion batteries have been widely used in the fields of mobile electronic devices, electric vehicles, large-scale energy storage devices, and the like due to their high energy density and long cycle life. The existing commercial anode materials comprise LiCoO2、LiFePO4、LiNixMnyO4、LiNixCoyMn1-x-y and the like, and although the performance of the commercial anode materials is good in different performance dimensions, the conventional commercial anode materials still have certain limitations in a high-power output and long-period stability method, and the use requirements of electric traffic and energy storage systems are difficult to meet. The spinel-structured lithium nickel manganese oxide (LiNi xMnyO4, x+y=2) has the advantages of three-dimensional lithium ion diffusion channel, excellent rate performance, low cost and the like, and becomes a high-voltage positive electrode material with great application potential. The material has a working voltage of about 4.7V, can provide higher energy density, and is suitable for power batteries and high-magnification application scenes. However, the material has technical bottlenecks in practical application, namely firstly, electrolyte is easy to be subjected to oxidative decomposition under high voltage to generate corrosive substances such as hydrofluoric acid and the like, so that the surface of the material is continuously corroded to destroy the surface structure and induce transition metal to dissolve out, and secondly, interface side reactions (such as unstable interface layer of a negative electrode, oxidation of a solvent and the like) induced by high voltage exacerbate capacity attenuation in the circulating process, and the circulating stability and the service life of the material are obviously influenced. In order to overcome the above problems, the prior art adopts modification means such as element doping or surface coating. The element doping can reduce phase change and volume change in the cyclic process, is beneficial to stabilizing the crystal structure and improving the stability of the material, but the element doping is difficult to combine the structural stability and the surface corrosion resistance, and has limited improvement effect. The surface coating is to coat a lithium-based compound such as LiNbO 3、Li3PO4 on the surface of the positive electrode material, and is used for constructing a protective layer to prevent the electrolyte from directly contacting with the active material, so that the interface stability is improved, the surface coating is easy to be damaged by stress and further to lose efficacy in long-term circulation although the interface stability is improved, and the surface coating cannot optimize the bulk phase structure of the material and cannot directly improve the stability of the material. Disclosure of Invention The invention aims to provide a composite modified lithium nickel manganese oxide positive electrode material, and a preparation method and application thereof. The composite modified lithium nickel manganese oxide anode material provided by the invention can simultaneously improve the structural stability and the interface stability of the material, and is suitable for high-rate, high-voltage and long-service-life lithium ion batteries. In order to achieve the above object, the present invention provides the following technical solutions: The invention provides a composite modified lithium nickel manganese oxide positive electrode material, which comprises a co-doped lithium nickel manganese oxide positive electrode material and a fast ion conductor coated outside the co-doped lithium nickel manganese oxide positive electrode material in situ; The doping elements in the co-doped lithium nickel manganese oxide positive electrode material comprise high-valence metal and low-valence metal, wherein the high-valence metal is one or more of metal with valence of +5, and the low-valence metal is one or more of metal with valence of +1 to +4 in any valence state; the fast ion conductor is a compound with a structural formula of LiMO 3, wherein M is a high-valence metal in the co-doped lithium nickel manganese oxide positive electrode material. Preferably, the thickness of the fast ion conductor is 5-30 nm. Preferably, the doping amount of the high-valence metal is 0.2-1% and the doping amount of the low-valence metal is 0.1-0.5% based on the mass of the lithium nickel manganese oxide positive electrode material in the co-doped lithium nickel manganese oxide positive electrode material. Preferably, the higher-valence metal comprises nio