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CN-121974411-A - Lithium-rich disordered lithium nickel manganese oxide positive electrode material and preparation method thereof

CN121974411ACN 121974411 ACN121974411 ACN 121974411ACN-121974411-A

Abstract

The invention discloses a lithium-rich disordered lithium nickel manganese oxide positive electrode material and a preparation method thereof. The material solves the technical bottleneck that the existing spinel lithium nickel manganese oxide has low capacity and poor structural stability under high multiplying power and cannot meet the quick charge requirement by regulating and controlling the disorder degree of lithium ions and transition metal sites. The preparation method comprises the steps of mixing a lithium source, a nickel source, a manganese source and a metal ion complexing agent according to a specific molar ratio, stirring into gel through water bath, vacuum drying and two-step sintering to obtain the target material. According to the invention, through the design of lithium enrichment and disorder degree regulation, the diffusion rate of lithium ions is obviously improved, the lattice stress in the charge and discharge process is relieved, the two-phase reaction and the dissolution of transition metal are inhibited, the discharge capacity reaches 110.5 mAh/g at 10C multiplying power, the capacity retention rate after 2000 times of circulation is 97.1%, the lithium-ion-enriched lithium ion battery has excellent multiplying power performance, circulation stability and thermal stability, and the lithium-ion-enriched lithium ion battery is suitable for high-power density scenes such as electric automobile quick charge systems, energy storage power stations and the like.

Inventors

  • WU JINSONG
  • WANG GUAN

Assignees

  • 武汉理工大学

Dates

Publication Date
20260505
Application Date
20260127

Claims (10)

  1. 1. The preparation method of the lithium-rich disordered lithium nickel manganese oxide positive electrode material is characterized by comprising the following steps of: (1) Mixing a lithium source, a nickel source, a manganese source and a metal ion complexing agent according to the molar ratio of (1+x): (0.5-x): 1.5:2, wherein the value range of x is 0.03-0.1, and forming a mixed solution in deionized water; (2) Heating the mixed solution in a water bath and stirring until water evaporates to form transparent dry gel; (3) Drying the gel under vacuum at 120 ℃ to 160 ℃; (4) And carrying out two-step sintering treatment on the dried material to obtain the lithium-rich disordered lithium nickel manganese oxide positive electrode material.
  2. 2. The method according to claim 1, wherein the lithium source is at least one selected from the group consisting of anhydrous lithium acetate, lithium carbonate dihydrate, lithium acetoacetate, lithium formate, lithium benzoate and lithium oxalate hydrate, the nickel source is at least one selected from the group consisting of nickel acetate tetrahydrate, nickel glycolate, nickel hydroxide, nickel acetylacetonate and nickel oxalate dihydrate, and the manganese source is at least one selected from the group consisting of anhydrous manganese acetate, manganese acetate tetrahydrate, manganese acetylacetonate and manganese gluconate.
  3. 3. The method according to claim 1, wherein the metal ion complexing agent is at least one selected from the group consisting of citric acid, polyvinylpyrrolidone, sodium alginate and acrylonitrile.
  4. 4. The method according to claim 1, wherein in the step (2), the water bath heating is performed at a temperature of 60 ℃ to 90 ℃.
  5. 5. The method according to claim 1, wherein in the step (4), the two-step sintering process comprises first sintering at a temperature of 400 to 500 ℃ for 4 to 6 hours, followed by sintering at a temperature of 800 to 900 ℃ for 10 to 15 hours.
  6. 6. A lithium-rich disordered lithium nickel manganese oxide cathode material, characterized in that it is prepared by the preparation method of any one of claims 1 to 5.
  7. 7. A lithium-rich disordered lithium nickel manganese oxide positive electrode material is characterized in that the chemical formula of the positive electrode material is Li 1+x Ni 0.5-x Mn 1.5 O 4 , wherein x is more than or equal to 0.03 and less than or equal to 0.1, and the positive electrode material has the characteristic of high disorder degree.
  8. 8. The lithium-rich disordered lithium nickel manganese oxide cathode material of claim 7, having a spinel structure and having a diffraction peak intensity attributed to the P4 3 space group ordering structure in the X-ray diffraction pattern that is significantly reduced relative to standard stoichiometric LiNi 0.5 Mn 1.5 O 4 material.
  9. 9. The lithium-rich disordered lithium nickel manganese oxide positive electrode material according to claim 7 or 8, wherein the retention rate of specific discharge capacity is not lower than 85% after 2000 cycles under the 10C rate charge-discharge condition.
  10. 10. A lithium ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the positive electrode comprises the lithium-rich disordered lithium nickel manganese oxide positive electrode material according to any one of claims 6 to 9 as an active material.

Description

Lithium-rich disordered lithium nickel manganese oxide positive electrode material and preparation method thereof Technical Field The invention belongs to the technical field of lithium ion batteries, and particularly relates to a lithium-rich disordered lithium nickel manganese oxide positive electrode material and a preparation method thereof, which are suitable for high-power density lithium ion batteries, in particular to large-current density application scenes such as electric car fast charging systems, energy storage power stations and the like. Background The spinel-structured lithium nickel manganese oxide (LiNi 0.5Mn1.5O4, LNMO for short) is used as a lithium ion battery anode material, has a 4.7V high-voltage platform, is free of cobalt, low in cost and fast ion transmission capacity brought by a three-dimensional lithium ion diffusion channel, has a theoretical specific capacity of 147 mAh/g, has an energy density remarkably superior to that of the traditional lithium iron phosphate and lithium cobalt oxide materials, and is a core candidate material of a next-generation high-power-density battery. However, the practical industrial application of LNMO still faces two key technical bottlenecks, namely that firstly, the rate performance is attenuated, when the lithium ion migration path is blocked by lattice distortion during high-current charge and discharge (10C and above), the body material is easy to crack, the utilization rate of active substances is reduced, the capacity is fast attenuated, secondly, the cyclic stability is insufficient, transition metal ions (especially Mn 3+) are dissolved and electrolyte is decomposed to cause interface side reaction in the high-voltage cyclic process, the structural degradation is aggravated, and the cyclic life is difficult to meet the industrial application requirements. The existing modification strategies are mainly focused on doping modification and surface coating, for example, transition metal dissolution is inhibited by doping aliovalent ions such as Al 3+、Mg2+ or electrolyte corrosion is blocked by adopting coatings such as Al 2O3、LiPO3, but the problems of complex process, higher cost, large-scale production difficulty and the like exist in the methods, and the problem of cooperative optimization of the internal structural stability and the ion transmission efficiency of the material cannot be fundamentally solved. Therefore, the development of a novel modification method improves the electrochemical performance by regulating and controlling the intrinsic structure of the material, and becomes a key direction for breaking through the application bottleneck of the LNMO. Disclosure of Invention Aiming at the technical defects that the existing spinel lithium nickel manganese oxide positive electrode material has low discharge capacity under high multiplying power, poor structural stability and incapability of adapting to a fast charge scene due to positive and negative crosstalk reaction, the invention provides the lithium-rich disordered lithium nickel manganese oxide positive electrode material and a preparation method thereof, and the diffusion rate and the structural stability of lithium ions are synchronously improved by regulating and controlling the internal disorder degree of the material. In order to achieve the above purpose, the invention provides a preparation method of a lithium-rich disordered lithium nickel manganese oxide positive electrode material, which comprises the following steps: (1) Mixing a lithium source, a nickel source, a manganese source and a metal ion complexing agent according to the molar ratio of (1+x): (0.5-x): 1.5:2, wherein the value range of x is 0.03-0.1, and forming a mixed solution in deionized water; (2) Heating the mixed solution in a water bath and stirring until water evaporates to form transparent dry gel; (3) Drying the gel under vacuum at 120 ℃ to 160 ℃; (4) And carrying out two-step sintering treatment on the dried material to obtain the lithium-rich disordered lithium nickel manganese oxide positive electrode material. Further, the lithium source is at least one selected from anhydrous lithium acetate, lithium carbonate dihydrate, lithium acetoacetate, lithium formate, lithium benzoate or lithium oxalate hydrate, the nickel source is at least one selected from nickel acetate tetrahydrate, nickel glycolate, nickel hydroxide, nickel acetylacetonate or nickel oxalate dihydrate, and the manganese source is at least one selected from anhydrous manganese acetate, manganese acetate tetrahydrate, manganese acetylacetonate or manganese gluconate. Further, the metal ion complexing agent is at least one selected from citric acid, polyvinylpyrrolidone, sodium alginate or acrylonitrile. Further, in the step (2), the water bath heating temperature is 60 ℃ to 90 ℃. Further, in step (4), the two-step sintering process includes first sintering at a temperature of 400 to 500 ℃ for 4 to 6 hours, followed by sinterin