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CN-121974408-A - Modified lithium-rich manganese-based positive electrode material, preparation method thereof and solid-state battery

CN121974408ACN 121974408 ACN121974408 ACN 121974408ACN-121974408-A

Abstract

The invention provides a modified lithium-rich manganese-based positive electrode material, a preparation method thereof and a solid-state battery. The method comprises the steps of mixing a manganese source, a nickel source and a cobalt source, adding deionized water and a dispersing agent into the mixture, adjusting the pH value to 8.5-11.5, performing coprecipitation reaction at 40-80 ℃ to 12-36 h, filtering, washing and drying to obtain a manganese-based precursor, ball-milling and mixing the manganese-based precursor, the lithium source, a main doping agent and an auxiliary doping agent to obtain mixed powder, heating the mixed powder to 800-1050 ℃ under the protection of inert gas, and preserving heat to 8-16 h. The modified lithium-rich manganese-based positive electrode material has improved structural stability, optimized electrochemical performance, improved specific capacity and cycling stability, improved rate capability and improved interface compatibility with solid electrolyte. The solid-state battery based on the material has excellent comprehensive performance, simplified preparation process and reduced cost, and is suitable for large-scale industrial production.

Inventors

  • SUN HUAPENG
  • LI TAISHI
  • XU JIANJUN
  • XIAO KEWEN
  • CHEN HANG

Assignees

  • 郴州新能源电池材料研究中心
  • 郴州市尚亿新能源有限公司
  • 郴江实验室

Dates

Publication Date
20260505
Application Date
20260408

Claims (10)

  1. 1. The preparation method of the modified lithium-rich manganese-based positive electrode material is characterized by comprising the following steps of: (1) Mixing a manganese source, a nickel source and a cobalt source, adding deionized water and a dispersing agent into the mixture, adjusting the pH value to 8.5-11.5, performing coprecipitation reaction at 40-80 ℃ to 12-36 h, and filtering, washing and drying the mixture to obtain a manganese-based precursor; (2) Ball-milling and mixing the manganese-based precursor prepared in the step (1) with a lithium source, a main dopant and an auxiliary dopant to obtain mixed powder; (3) Heating the mixed powder obtained in the step (2) to 800-1050 ℃ at a temperature of 3-6 ℃ per min under the protection of inert gas, and preserving heat for 8-16 h, wherein: The main dopant is a mixture of Cr 2 O 3 、WO 3 and ZrO 2 , and the auxiliary dopant is a mixture of B 2 O 3 and Al 2 O 3 ; In the step (1), based on 100 percent of the total weight of the manganese source, the nickel source, the cobalt source and the dispersing agent, the manganese source accounts for 60 to 85 percent by weight, the nickel source accounts for 8 to 25 percent by weight, the cobalt source accounts for 3 to 15 percent by weight, and the dispersing agent accounts for 0.5 to 2 percent by weight; In the step (2), the manganese-based precursor accounts for 75 to 90 wt%, the lithium source accounts for 8 to 20 wt%, the main dopant accounts for 0.8 to 4.2 wt%, and the auxiliary dopant accounts for 0.1 to 1.4 wt%, based on 100% of the total weight of the manganese-based precursor, the lithium source, the main dopant and the auxiliary dopant.
  2. 2. The method for preparing a modified lithium-rich manganese-based positive electrode material according to claim 1, wherein the main dopant is a mixture of Cr 2 O 3 、WO 3 and ZrO 2 in a weight ratio of 2-4:1-3:1-2.
  3. 3. The method for preparing a modified lithium-rich manganese-based positive electrode material according to claim 1, wherein the auxiliary dopant is a mixture of B 2 O 3 and Al 2 O 3 in a weight ratio of 2:1 to 3:1.
  4. 4. The method for preparing a modified lithium-rich manganese-based positive electrode material according to claim 1, wherein the dispersing agent is a mixture of polyvinylpyrrolidone and sodium citrate in a weight ratio of 1:1-2:1.
  5. 5. The method for preparing the modified lithium-rich manganese-based positive electrode material according to claim 1, wherein the manganese source is selected from one or more of manganese sulfate, manganese chloride, manganese nitrate and manganese acetate, the nickel source is selected from one or more of nickel sulfate, nickel chloride, nickel nitrate and nickel acetate, the cobalt source is selected from one or more of cobalt sulfate, cobalt chloride, cobalt nitrate and cobalt acetate, the lithium source is selected from one or more of lithium carbonate, lithium hydroxide and lithium nitrate, and the dispersing agent is selected from one or more of polyvinylpyrrolidone, polyethylene glycol, sodium dodecyl benzene sulfonate and sodium citrate.
  6. 6. The method for preparing a modified lithium-rich manganese-based positive electrode material according to claim 1, wherein in the step (2), the ball milling speed of ball milling and mixing is 200-400 r/min, the ball milling time is 2-6 h, and the ball-material ratio is 10:1-20:1.
  7. 7. The method for preparing a modified lithium-rich manganese-based positive electrode material according to claim 1, further comprising, after step (3): (4) And (3) crushing and sieving the material obtained in the step (3).
  8. 8. The method of preparing a modified lithium-rich manganese-based positive electrode material according to claim 1, wherein in the step (1), a ratio of a weight of deionized water to a total weight of the manganese source, the nickel source, the cobalt source, and the dispersant is in a range of 1.5:1 to 4:1.
  9. 9. A modified lithium-rich manganese-based positive electrode material, characterized in that the modified lithium-rich manganese-based positive electrode material is prepared according to the method of any one of claims 1 to 8.
  10. 10. A solid-state battery comprising a positive electrode sheet, a negative electrode sheet, a solid-state electrolyte layer, and a housing, the positive electrode sheet comprising the modified lithium-rich manganese-based positive electrode material of claim 9.

Description

Modified lithium-rich manganese-based positive electrode material, preparation method thereof and solid-state battery Technical Field The invention belongs to the technical field of solid-state batteries, and particularly relates to a modified lithium-rich manganese-based positive electrode material, a preparation method thereof and a solid-state battery. Background The lithium-rich manganese-based positive electrode material is used as an important branch of a layered oxide lithium battery positive electrode material, takes manganese as a main transition metal element, has higher lithium content than a conventional layered positive electrode material, and has a solid solution or two-phase composite structure. The theoretical specific capacity of the lithium-rich manganese-based positive electrode material can reach 400-450 mAh/g by means of a charge compensation mechanism of cooperation of transition metal cations and lattice oxygen anions, is superior to the traditional positive electrodes such as lithium cobaltate, ternary materials and the like, has the advantages of high energy density, low cost and high safety, becomes a core candidate material of a next-generation high-energy-density battery, and has wide application prospect in the field of solid-state batteries. Since the first report of the 90 th century, research on lithium-rich manganese-based cathode materials has been continuously advanced, and early Li-Mn-O systems have the problems of low specific capacity, poor cycle stability and the like, and subsequently, by introducing elements such as Ni, co and the like for doping modification, the actual specific capacity is increased to 250-300 mAh/g, so that the lithium-rich manganese-based cathode materials become a research hotspot. With the rise of solid-state battery technology, the matching research of the material and solid-state electrolytes such as halides, sulfides and the like is gradually in depth, and the material becomes an important direction for improving the energy density of the solid-state battery. At present, modification means such as bulk phase doping, surface coating, structure reconstruction and the like are mainly adopted in the industry to optimize the performance, wherein the bulk phase doping can pertinently inhibit the problems of Jahn-Teller effect, transition metal ion dissolution, cation mixing and the like by introducing different types of ions. Although research has been advanced to a certain extent, the lithium-rich manganese-based positive electrode material still has a plurality of technical defects in practical application, and particularly in a solid-state battery system, related problems are more prominent, so that the commercialization process of the lithium-rich manganese-based positive electrode material is restricted. Firstly, the structural stability is poor, the voltage attenuation is serious, the irreversible degradation of the lattice structure is easy to occur in the charge-discharge cycle, the layered structure is converted to spinel phase and rock salt phase, meanwhile, the cation mixing and discharging block Li + from diffusing, and the lattice oxygen is irreversibly separated out to form oxygen vacancies, so that the initial coulomb efficiency is lower, and the voltage attenuation rate is faster. Secondly, transition metal ions are easy to dissolve and migrate, side reactions are generated with the solid electrolyte, the electrolyte is catalyzed to decompose and destroy electrode/electrolyte interfaces, interface impedance is increased, battery cycle stability and rate capability are obviously reduced, and the problem is particularly serious in a halide solid electrolyte system. Thirdly, in the prior art, single ion doping or multi-element doping is adopted, but the content proportion is lack of optimization, so that the defect of multiple performances is difficult to solve simultaneously, and the component content is represented by the molar ratio, so that the accurate proportion of raw materials in industrial production is not facilitated, and the performance of the product is fluctuated. Fourth, the preparation process is complex and high in cost, the main stream high-temperature sintering, sol-gel method and the like have the problems of high sintering temperature, long heat preservation time and high raw material cost, the uniform dispersion of the multi-component doping components is difficult to realize, the performance difference among product batches is large, and the large-scale production difficulty is high. Therefore, development of the multielement synergistic modified lithium-rich manganese-based positive electrode material suitable for the solid-state battery and a simple and efficient preparation method have important industrial application values. Disclosure of Invention Based on the technical problems described above, the invention aims to overcome the defects of poor structural stability, serious voltage attenuation, poor interf