WO2024131123A1 - 富镍层状氧化物材料及其制备方法和应用 - Google Patents

富镍层状氧化物材料及其制备方法和应用 Download PDF

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WO2024131123A1
WO2024131123A1 PCT/CN2023/115761 CN2023115761W WO2024131123A1 WO 2024131123 A1 WO2024131123 A1 WO 2024131123A1 CN 2023115761 W CN2023115761 W CN 2023115761W WO 2024131123 A1 WO2024131123 A1 WO 2024131123A1
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source compound
nickel
oxide material
layered oxide
rich layered
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PCT/CN2023/115761
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English (en)
French (fr)
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李红磊
唐淼
张海天
吉长印
吕菲
徐宁
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天津巴莫科技有限责任公司
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Publication of WO2024131123A1 publication Critical patent/WO2024131123A1/zh

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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • the present application belongs to the field of battery materials, and in particular relates to a nickel-rich layered oxide material and a preparation method and application thereof.
  • LiNiO2 materials have the advantages of high specific capacity, abundant resources and low cost, but they have obvious defects such as Li + /Ni 2+ cation mixed arrangement, non-stoichiometric ratio and high delithiation safety issues, which hinder their practical application.
  • metal ions such as Co, Mn, Al, Mg, and Ti to partially replace Ni 3+ to form binary or ternary layered oxides to improve the structural stability and cycle performance of the materials.
  • the ratio of Co and Mn is flexibly adjusted to balance the material components and electrochemical properties, and nickel-rich NCM or NCA ternary positive electrode materials with higher energy density are constructed.
  • nickel-rich NCM or NCA ternary positive electrode materials with higher energy density are constructed.
  • the anisotropic contraction and expansion of primary particles caused by H2-H3 phase transition will aggravate the stress inside the material, induce the generation and expansion of microcracks inside the material, and then lead to the separation and pulverization between primary particles, accelerate the side reaction between electrolyte and microcracks, and finally lead to material failure.
  • the present application provides a nickel-rich layered oxide material, wherein the crystal structure of the nickel-rich layered oxide material is a hexagonal phase R-3m space group, and the lattice microscopic strain is ⁇ 0.25%.
  • the nickel-rich layered oxide material is in the form of particles.
  • the types of metal cations contained in B, C and D at least two metal cations are present on the surface of the primary particles of the nickel-rich layered oxide material.
  • the concentration is greater than that at the center of the primary particle.
  • A is one or more of Mg 2+ , Ni 2+ and Sr 2+ ;
  • B is one or more of Al 3+ , Co 3+ , Ga 3+ , Y 3+ , La 3+ and Yb 3+ ;
  • C is one or more of Mn 4+ , Zr 4+ , Ti 4+ , Sn 4+ and Ce 4+ ;
  • D is one or more of V 5+ , Nb 5+ , Sb 5+ , Ta 5+ , Mo 6+ and W 6+ .
  • the nickel-rich layered oxide material satisfies at least one of the following conditions:
  • the D 50 particle size of the nickel-rich layered oxide material is 2 to 20 ⁇ m
  • the specific surface area of the nickel-rich layered oxide material is 0.2 to 2 m 2 /g;
  • the nickel-rich layered oxide material has a morphology of primary particles or spherical secondary particles.
  • the present application provides a method for preparing a nickel-rich layered oxide material, comprising the following steps:
  • the components of solution I include a nickel source compound and water; the components of solution II include a first metal source compound and water; the first metal source compound is at least one of a C source compound and a D source compound, or a mixture of at least one of a C source compound and a D source compound and at least one of an A source compound and a B source compound; the A source compound is a water-soluble metal salt corresponding to a +2-valent metal cation, the B source compound is a water-soluble metal salt corresponding to a +3-valent metal cation, the C source compound is a water-soluble metal salt corresponding to a +4-valent metal cation, and the D source compound is a water-soluble metal salt corresponding to a +5-valent or higher metal cation;
  • the second metal source compound is one or more of source compound A, source compound B, source compound C and source compound D;
  • nickel-rich layered oxide material has a crystal structure of a hexagonal phase R-3m space group, and a lattice microscopic strain of ⁇ 0.25%.
  • the concentration of metal ions in the solution I is 1-5 mol/L; and the total concentration of metal ions in the solution II is 0.5-5 mol/L.
  • the sodium hydroxide is mixed in the form of a sodium hydroxide aqueous solution, and the concentration of the sodium hydroxide aqueous solution is 0.5-4 mol/L;
  • the complexing agent is one or more of ammonia water, ethylenediaminetetraacetic acid and ethylenediamine, and the complexing agent is mixed in the form of a complexing agent aqueous solution, and the concentration of the complexing agent aqueous solution is 0.5-10 mol/L.
  • step a) the complexation and precipitation reaction is carried out under stirring conditions with a stirring rate of 200 to 1000 r/min; the temperature of the complexation and precipitation reaction is 30 to 70° C.; and the time of the complexation and precipitation reaction is 10 to 50 h.
  • step c) the specific process of the stepwise calcination includes:
  • the first calcination temperature is 300-600°C; the heating rate to the first calcination temperature is 1-6°C/min; the time of the first heat preservation calcination is 4-10h;
  • the second calcination temperature is 700-1000°C; the heating rate to the second calcination temperature is 1-6°C/min; the second heat preservation calcination time is 1-5h;
  • the third roasting temperature is 700-900° C., and the third roasting temperature is less than or equal to the second roasting temperature; the rate of adjusting the temperature to the third roasting temperature is 0-10° C./min; and the time of the three heat preservation roastings is 10-20 hours.
  • oxygen is continuously introduced into the calcining equipment during the stepwise calcining process to provide an oxygen-containing atmosphere required for calcination;
  • the oxygen intake rate of step i) is 0.5-5 m 3 /h
  • the oxygen intake rate of step ii) is 0.5-5 m 3 /h
  • the oxygen intake rate of step iii) is 0.5-5 m 3 /h.
  • the first metal source compound includes an A source compound, a B source compound, a C source compound, and optionally a D source compound.
  • the A source compound, B source compound, C source compound or D source compound in the second metal source compound is a carbonate, hydroxide or oxide of a +2-valent metal cation, a +3-valent metal cation, a +4-valent metal cation or a +5-valent metal cation.
  • the present application provides a lithium-ion secondary battery, wherein the positive electrode material of the lithium-ion secondary battery comprises the nickel-rich layered oxide material described in the above technical solution or the nickel-rich layered oxide material prepared by the preparation method described in the above technical solution.
  • the present application provides a nickel-rich layered oxide material and its preparation method and application.
  • the crystal structure of the nickel-rich layered oxide material provided by the present application is a hexagonal phase R-3m space group, and the lattice microscopic strain is ⁇ 0.25%.
  • the present application uses a high entropy system design of multivalent and multi-type metal cations, combined with the optimization of precursor (hydroxide precipitation) components and calcination formulas, and utilizes the hysteresis diffusion effect of high entropy components during the calcination process to regulate the internal element distribution of the material, induce particles to grow in a low stress direction, and reduce the microscopic strain intensity in the crystal structure of the bulk material.
  • the nickel-rich layered oxide material provided by the present invention application has a low microscopic strain and has good structural stability and safety at high potentials.
  • FIG1 is a SEM image of the nickel-rich layered oxide material of Example 1 provided in the present application.
  • FIG2 is a distribution diagram of Zr and W elements at different depths on the surface of primary particles in the nickel-rich layered oxide material of Example 1 provided by the present application;
  • FIG3 is an XRD diagram of the nickel-rich layered oxide of Example 1 provided in the present application and its LeBail structure refinement diagram;
  • FIG4 is a Williamson-Hall diagram of the oxide materials prepared in Example 1 and Comparative Examples 1 to 3 provided in the present application;
  • FIG5 is a comparison chart of the cycle performance of the oxide materials prepared in Example 1 and Comparative Examples 1 to 3 provided in the present application in a lithium secondary battery test.
  • High entropy materials are single-phase materials containing five or more elements that are mutually dissolved in equal or near molar ratios. They exhibit unique effects in thermodynamics, kinetics, microstructure and performance, such as high entropy effect, hysteresis diffusion effect, lattice distortion effect, etc. This application combines the performance advantages of high entropy materials to optimize the structural characteristics of positive electrode materials, and develops lithium battery positive electrode materials with good structural stability and safety at high potentials.
  • the present application provides a nickel-rich layered oxide material and its preparation method and application.
  • the core technical problem to be solved is that the nickel-rich layered oxide positive electrode material has poor structural stability and safety due to the H2-H3 phase transition at high potential.
  • the present application designs a high-entropy system of multivalent and multi-type metal cations, combines the optimization of precursor components and calcination formulas, utilizes the hysteresis diffusion effect of high-entropy components during the calcination process, regulates the internal element distribution of the material, induces particles to grow in a low-stress direction, reduces the microscopic strain strength in the crystal structure of the bulk material, thereby reducing the stress accumulation of the material at high potential and improving the structural stability and safety.
  • the key difference between the technical solution of the present application and the traditional metal ion-doped nickel-rich layered oxide material is that the traditional single metal ion or multi-metal ion doping usually improves the stability of the crystal structure with a higher metal-oxygen bond energy; while the nickel-rich layered oxide in the present application is formed by introducing multivalent and multi-type metal cations to form a nickel-rich high-entropy solid solution, optimizing the precursor components and calcination formula, and utilizing the special effect of the high-entropy component in the calcination process (hysteresis diffusion effect) to reduce the microscopic strain in the crystal structure of the material, thereby alleviating the stress accumulation under high potential and achieving electrochemical Improved academic performance and safety.
  • the present application provides a nickel-rich layered oxide material, the crystal structure of which is a hexagonal phase R-3m space group, and the lattice microscopic strain is ⁇ 0.25%.
  • the lattice microscopic strain can be specifically 0.05%, 0.08%, 0.14%, 0.16%, 0.19% or 0.22%.
  • the general chemical formula of the nickel-rich layered oxide material can be: LiNi x A a B b C c D d O 2 ; wherein Ni is +3-valent; A is a +2-valent metal cation, for example, one or more of Mg 2+ , Ni 2+ and Sr 2+ ; B is a +3-valent metal cation, for example, one or more of Al 3+ , Co 3+ , Ga 3+ , Y 3+ , La 3+ and Yb 3+ ; C is a +4-valent metal cation, for example, one or more of Mn 4+ , Zr 4+ , Ti 4+ , Sn 4+ and Ce 4+ ; D is a +5-valent or higher metal cation, for example, one or more of V 5+ , Nb 5+ , Sb 5+ , Ta 5+ , Mo 6+ and W 6+ ; 0.8 ⁇ x ⁇ 1, a>0, b>0, c>0,
  • the nickel-rich layered oxide material may be in the form of particles.
  • at least two metal cations have a concentration greater at the surface of the primary particles of the nickel-rich layered oxide material than at the center of the primary particles.
  • the concentration gradient of two or more metal cations in the primary particles can stabilize the surface structure of the material through a synergistic effect, inhibit the loss of oxygen at high potential, and improve the electrochemical stability of the material.
  • the at least two metal cations whose concentration at the surface of the primary particle is greater than that at the center of the primary particle can be either metal cations of the same valence or metal cations of different valences, and the present application does not make any special limitation.
  • the D50 particle size of the nickel-rich layered oxide material can be 2 to 20 ⁇ m, for example, 2 ⁇ m, 3 ⁇ m, 3.2 ⁇ m, 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 7 ⁇ m, 8 ⁇ m, 9 ⁇ m, 10 ⁇ m, 10.2 ⁇ m, 10.5 ⁇ m, 11 ⁇ m, 12 ⁇ m, 12.5 ⁇ m, 13 ⁇ m, 14 ⁇ m, 15 ⁇ m, 16 ⁇ m, 17 ⁇ m, 18 ⁇ m, 19 ⁇ m or 20 ⁇ m.
  • the specific surface area of the nickel-rich layered oxide material can be 0.2 to 2 m 2 /g, for example, 0.2 m 2 /g, 0.25 m 2 /g, 0.3 m 2 /g, 0.33 m 2 /g, 0.35 m 2 /g, 0.4 m 2 /g, 0.42 m 2 /g, 0.45 m 2 /g, 0.46 m 2 /g, 0.5 m 2 /g, 0.55 m 2 /g, 0.6 m 2 /g, 0.7 m 2 /g, 0.76 m 2 /g, 0.8 m 2 /g, 0.9 m 2 /g, 1 m 2 /g, 1.1 m 2 /g, 1.2 m 2 / g, 1.3 m 2 /g, 1.4 m 2 /g, 1.5 m 2 /g, 1.6 m 2 / g , 1.7 m 2 / g
  • the nickel-rich layered oxide material may have a primary particle or a spherical secondary particle morphology.
  • the chemical formula of the nickel-rich layered oxide material is any one of the following chemical formulas: LiNi 0.874 Sr 0.0045 Co 0.058 Al 0.015 Mn 0.0388 Zr 0.0078 W 0.0019 O 2 ; LiNi 0.814 Mg 0.003 Co 0.108 Al 0.01 Mn 0.058 Ti 0.0048 Ta 0.0022 O 2 ; LiNi 3+ 0.905 Ni 2+ 0.004 Co 0.059 Y 0.005 Mn 0.019 Zr 0.0058 Nb 0.0022 O 2 ; LiNi 0.867 Mg 0.005 Co 0.108 Al 0.01 Zr 0.004 Ti 0.004 W 0.002 O 2 ; LiNi 0.818 Sr 0.006 Co 0.060 Yb 0.005 Mn 0.109 Ta 0.002 O 2 ; LiNi 3+ 0.9 Ni 2+ 0.004 Co 0.039 Al 0.01 Mn 0.039 Zr 0.006 W 0.002 O 2 ; LiNi 0.9
  • the present application also provides a method for preparing the nickel-rich layered oxide material described in the above technical solution, comprising the following steps:
  • the components of the solution I include a nickel source compound and water;
  • the nickel source compound is a soluble salt of nickel, for example, one or more of nickel sulfate, chloride and nitrate;
  • the concentration of metal ions in the solution I can be 1 to 5 mol/L, for example, 1 mol/L, 1.5 mol/L, 2 mol/L, 2.5 mol/L, 3 mol/L, 3.5 mol/L, 4 mol/L, 4.5 mol/L or 5 mol/L.
  • the components of the solution II include a first metal source compound and water; the first metal source compound is at least one of the C source compound and the D source compound, or a mixture of at least one of the C source compound and the D source compound and at least one of the A source compound and the B source compound.
  • the A source compound, the B source compound, the C source compound and the D source compound are water-soluble metal salts corresponding to the +2-valent metal cation A, +3-valent metal cation B, +4-valent metal cation C and +5-valent and above metal cation D introduced above, respectively.
  • the metal element in the water-soluble metal salt is consistent with the corresponding metal cation, and the valence state can be the same or different, without special limitation.
  • the total concentration of metal ions in the solution II is preferably 0.5-5 mol/L, specifically 0.5 mol/L, 1 mol/L, 1.5 mol/L, 2 mol/L, 2.5 mol/L, 3 mol/L, 3.5 mol/L, 4 mol/L, 4.5 mol/L or 5 mol/L.
  • the first metal source compound includes an A source compound, a B source compound, and a C source compound.
  • the first metal source compound includes an A source compound, a B source compound, a C source compound, and a D source compound.
  • the sodium hydroxide in the preparation method provided in the present application, in step a), can be mixed in the form of a sodium hydroxide aqueous solution.
  • concentration of the sodium hydroxide aqueous solution can be 0.5 to 4 mol/L, for example, 0.5 mol/L, 1 mol/L, 1.5 mol/L, 2 mol/L, 2.5 mol/L, 3 mol/L, 3.5 mol/L or 4 mol/L.
  • the complexing agent in the preparation method provided in the present application, in step a), can be ammonia water, ethylenediaminetetraacetic acid and ethyl One or more of diamines.
  • the complexing agent can be mixed in the form of a complexing agent aqueous solution.
  • the concentration of the complexing agent aqueous solution can be 0.5 to 10 mol/L, for example, 0.5 mol/L, 1 mol/L, 1.5 mol/L, 2 mol/L, 2.5 mol/L, 3 mol/L, 3.5 mol/L, 4 mol/L, 4.5 mol/L, 5 mol/L, 5.5 mol/L, 6 mol/L, 6.5 mol/L, 7 mol/L, 7.5 mol/L, 8 mol/L, 8.5 mol/L, 9 mol/L, 9.5 mol/L or 10 mol/L.
  • the stirring rate may be 200-1000 r/min, for example, 200 r/min, 250 r/min, 300 r/min, 350 r/min, 400 r/min, 450 r/min, 500 r/min, 550 r/min, 600 r/min, 650 r/min, 700 r/min, 750 r/min, 800 r/min, 850 r/min, 900 r/min, 950 r/min or 1000 r/min.
  • the temperature of the complexation and precipitation reaction may be 30-70°C, for example, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 56°C, 60°C, 65°C or 70°C.
  • the complexation and precipitation reaction time may be 10 to 50 h, for example, 10 h, 15 h, 20 h, 25 h, 30 h, 35 h, 40 h, 42 h, 45 h or 50 h.
  • the obtained hydroxide precipitate may be washed and dried.
  • the drying temperature may be 100-300°C, for example, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C or 300°C.
  • the lithium source compound in step b), can be one or more of LiOH, Li 2 CO 3 , Li 2 SO 4 , LiCl and LiNO 3.
  • the second metal source compound is one or more of A source compound, B source compound, C source compound and D source compound.
  • the A source compound, B source compound, C source compound or D source compound in the second metal source compound may be different from the A source compound, B source compound, C source compound or D source compound in the first metal source compound.
  • the A source compound, the B source compound, the C source compound or the D source compound in the second metal source compound may be a carbonate, a hydroxide or an oxide of A, B, C or D.
  • the oxygen-containing atmosphere includes but is not limited to air and pure oxygen, for example, pure oxygen.
  • the first roasting temperature may be 300-600°C, for example, 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C or 600°C.
  • the heating rate of heating to the first calcination temperature may be 1 to 6°C/min, for example, 1°C/min, 1.5°C/min, 2°C/min, 2.5°C/min, 3°C/min, 3.5°C/min, 4°C/min, 4.5°C/min, 5°C/min, 5.5°C/min or 6°C/min.
  • the time of the first heat preservation calcination may be 4 to 10h, for example, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h or 10h.
  • the second calcination temperature may be 700-1000°C, for example, 700°C, 710°C, 720°C, 730°C, 740°C, 750°C, 760°C, 770°C, 780°C, 790°C, 800°C, 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C, 890°C, 900°C, 910°C, 920°C, 930°C, 940°C, 950°C, 960°C, 970°C, 980°C, 990°C or 1000°C.
  • the heating rate of the second calcination temperature may be 1 to 6°C/min, for example, 1°C/min, 1.5°C/min, 2°C/min, 2.5°C/min, 3°C/min, 3.5°C/min, 4°C/min, 4.5°C/min, 5°C/min, 5.5°C/min or 6°C/min.
  • the time of the secondary heat preservation calcination may be 1 to 5h, for example, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h or 5h.
  • the third roasting temperature may be 700-900°C, for example, 700°C, 710°C, 720°C, 730°C, 740°C, 750°C, 760°C, 770°C, 780°C, 790°C, 800°C, 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C, 890°C or 900°C, and the third roasting temperature is ⁇ the second roasting temperature.
  • the rate of temperature adjustment to the third roasting temperature can be 0 to 10°C/min, for example, 0 (i.e., no temperature adjustment), 0.5°C/min, 1°C/min, 1.5°C/min, 2°C/min, 2.5°C/min, 3°C/min, 3.5°C/min, 4°C/min, 4.5°C/min, 5°C/min, 5.5°C/min, 6°C/min, 6.5°C/min, 7°C/min, 7.5°C/min, 8°C/min, 8.5°C/min, 9°C/min, 9.5°C/min or 10°C/min.
  • the time for the three heat preservation calcinations may be 10 to 20 hours, for example, 10 hours, 10.5 hours, 11 hours, 11.5 hours, 12 hours, 12.5 hours, 13 hours, 13.5 hours, 14 hours, 14.5 hours, 15 hours, 15.5 hours, 16 hours, 16.5 hours, 17 hours, 17.5 hours, 18 hours, 18.5 hours, 19 hours, 19.5 hours or 20 hours.
  • oxygen can be continuously introduced into the roasting equipment used during the stepwise roasting process to provide the oxygen-containing atmosphere required for roasting.
  • the oxygen intake rate of step i) can be 0.5-5m 3 /h, for example, 0.5m 3 /h, 1m 3 /h, 1.5m 3 /h, 2m 3 /h, 2.5m 3 /h, 3m 3 /h, 3.5m 3 /h, 4m 3 /h, 4.5m 3 /h or 5m 3 /h.
  • the oxygen intake rate of step ii) can be 0.5-5m 3 /h, for example, 0.5m 3 /h, 1m 3 /h, 1.5m 3 /h, 2m 3 /h, 2.5m 3 /h, 3m 3 /h, 3.5m 3 /h, 4m 3 /h, 4.5m 3 /h or 5m 3 /h.
  • the oxygen inlet rate of step iii) may be 0.5-5 m 3 /h, for example 0.5 m 3 /h, 1 m 3 /h, 1.5 m 3 /h, 2 m 3 /h, 2.5 m 3 /h, 3 m 3 /h, 3.5 m 3 /h, 4 m 3 /h, 4.5 m 3 /h or 5 m 3 /h.
  • the obtained product can be cooled and then crushed and screen.
  • the present application also provides a lithium-ion secondary battery, comprising a positive electrode, a negative electrode, an electrolyte and a separator between the positive electrode and the negative electrode; wherein the material of the positive electrode comprises the nickel-rich layered oxide material described in the above technical solution or the nickel-rich layered oxide material prepared by the preparation method described in the above technical solution.
  • the present application also provides an electrical device, wherein the electrical device is equipped with the lithium-ion secondary battery described in the above technical solution.
  • the stirring speed of the mixed solution in the reactor is set to 800 r/min, and the reaction temperature is 50 ⁇ 1°C. After the reaction is continued for 40 hours, the obtained precipitate is discharged, washed with deionized water and dried at a drying temperature of 150°C to obtain a hydroxide precursor X.
  • hydroxide precursor X 873.6 g of LiOH and 10.9 g of Sr(OH) 2 were fully mixed using a high-speed mixer to obtain a mixture Y.
  • the mixture Y is placed in an oxygen atmosphere furnace for step-by-step roasting.
  • Oxygen is continuously introduced into the furnace during the whole roasting process.
  • the specific process is: firstly, the temperature is raised to 550°C for roasting for 4 hours (the heating rate is 3°C/min, and the oxygen intake rate is 3m3 /h), then the temperature is raised to 800°C for roasting for 1 hour (the heating rate is 3°C/min, and the oxygen intake rate is 4m3 /h), and then the temperature is lowered to 780°C for roasting for 14 hours (the cooling rate is 4°C/min, and the oxygen intake rate is 3m3 /h).
  • the furnace is cooled, and then the product is crushed and sieved to obtain a nickel-rich layered oxide material with a chemical formula of LiNi 0.874 Sr 0.0045 Co 0.058 Al 0.015 Mn 0.0388 Zr 0.0078 W 0.0019 O 2 .
  • the nickel-rich layered oxide material prepared in this example was observed by scanning electron microscopy (SEM), and the result is shown in Figure 1, which is a SEM image of the nickel-rich layered oxide material in Example 1 provided by the present application.
  • the material has a smooth surface and is a spherical secondary particle formed by agglomeration of primary particles (D 50 particle size of about 400 nm), and the particle size of the secondary particles is about 12.8 ⁇ m.
  • the D 50 particle size and specific surface area of the nickel-rich layered oxide material prepared in this example were tested, and the results showed that the median particle size D 50 was 12.5 ⁇ m, and the specific surface area was 0.45 m 2 /g.
  • the nickel-rich layered oxide prepared in this embodiment was detected by time-of-flight secondary ion mass spectrometry (ToF-SIMS).
  • the metal ion concentration at different depths of the material was detected, and the sputtering rate was set to 0.15nm/s.
  • Figure 2 is a distribution diagram of Zr and W elements at different depths on the surface of primary particles in the nickel-rich layered oxide material of Example 1 provided by the present application. It can be seen from Figure 2 that the concentration of Zr and W elements within 50nm of the surface depth of the primary particles is much higher than the concentration at the center of the primary particles.
  • the nickel-rich layered oxide material prepared in this embodiment was subjected to an X-ray diffraction (XRD) test.
  • the experimental results are shown in FIG3 , which is an XRD diagram of the nickel-rich layered oxide in Example 1 provided by the present application and its LeBail structure refinement diagram. It can be seen from FIG3 that the diffraction peak of the material corresponds to a hexagonal layered structure, R-3m space group.
  • the stirring speed of the mixed solution in the reactor was set to 800 r/min, and the reaction temperature was 55 ⁇ 1°C. After the reaction was continued for 36 hours, the obtained precipitate was discharged, washed with deionized water and dried at a drying temperature of 150°C to obtain a hydroxide precursor X.
  • the hydroxide precursor X, 769.6 g of Li 2 CO 3 , 5 g of MgCO 3 , 15.6 g of Al(OH) 3 and 9.7 g of Ta 2 O 5 were fully mixed in a high-speed mixer to obtain a mixture Y.
  • the mixture Y is placed in an oxygen atmosphere furnace for step-by-step roasting.
  • Oxygen is continuously introduced into the furnace during the whole roasting process.
  • the specific process is: firstly, the temperature is raised to 500°C for roasting for 6h (the heating rate is 4°C/min, and the oxygen intake rate is 2m3 /h), then the temperature is raised to 820°C for roasting for 2h (the heating rate is 4°C/min, and the oxygen intake rate is 5m3 /h), and then the temperature is lowered to 810°C for roasting for 10h (the cooling rate is 5°C/min, and the oxygen intake rate is 3m3 /h).
  • the product was cooled in the furnace, and then crushed and sieved to obtain nickel-rich layered oxide with the chemical formula of LiNi 0.814 Mg 0.003 Co 0.108 Al 0.01 Mn 0.058 Ti 0.0048 Ta 0.0022 O 2 .
  • the nickel-rich layered oxide material prepared in this example was characterized.
  • the results showed that the secondary particles were spherical in shape, the average particle size D 50 was 10.2 ⁇ m, the specific surface area was 0.55 m 2 /g, and the concentrations of Ti and Ta elements within 50 nm of the primary particle surface were much higher than those at the center of the primary particle.
  • hydroxide precursor X 873.6 g of LiOH, 11.3 g of Y 2 O 3 and 5.8 g of Nb 2 O 5 were fully mixed in a high-speed mixer to obtain a mixture Y.
  • the mixture Y is placed in an oxygen atmosphere furnace for step-by-step roasting.
  • Oxygen is continuously introduced into the furnace during the whole roasting process.
  • the specific process is: firstly, the temperature is raised to 500°C for roasting for 6h (the heating rate is 4°C/min, and the oxygen intake rate is 2m3 /h), then the temperature is raised to 850°C for roasting for 3h (the heating rate is 4°C/min, and the oxygen intake rate is 2m3 /h), and then the temperature is lowered to 800°C for roasting for 11h (the cooling rate is 5°C/min, and the oxygen intake rate is 2m3 /h).
  • the furnace is cooled, and then the product is crushed and sieved to obtain nickel-rich layered oxide with the chemical formula of LiNi 3+ 0.905 Ni 2+ 0.004 Co 0.059 Y 0.005 Mn 0.019 Zr 0.0058 Nb 0.0022 O 2 .
  • the nickel-rich layered oxide material prepared in this example was characterized. The results showed that the morphology was monodispersed primary particles, the median particle size D 50 was 3.0 ⁇ m, the specific surface area was 0.76 m 2 /g, and the concentrations of Y, Zr, and Nb elements within 50 nm of the primary particle surface were much higher than those at the center of the primary particles.
  • the stirring speed of the mixed solution in the reactor was set to 600 r/min, and the reaction temperature was 55 ⁇ 1°C. After the reaction was continued for 50 hours, the obtained precipitate was discharged, washed with deionized water, and dried at a drying temperature of 120°C to obtain a hydroxide precursor X.
  • hydroxide precursor X 873.6 g of LiOH, 8.4 g of MgCO 3 , 10.2 g of Al 2 O 3 and 9.3 g of WO 3 were fully mixed in a high-speed mixer to obtain a mixture Y.
  • the mixture Y is placed in an oxygen atmosphere furnace for stepwise calcination.
  • Oxygen is continuously introduced into the furnace during the whole calcination process.
  • the specific process is as follows: firstly, the temperature is raised to 550°C and calcined for 5h (the heating rate is 4°C/min, and the oxygen intake rate is 5m3 /h). Then the temperature was raised to 760°C and roasted for 2 hours (the heating rate was 4°C/min, the oxygen intake rate was 3 m 3 /h), and then the temperature was maintained at 760°C for 10 hours (the oxygen intake rate was 3 m 3 /h).
  • the furnace is cooled, and then the product is crushed and sieved to obtain nickel-rich layered oxide with a chemical formula of LiNi 0.867 Mg 0.005 Co 0.108 Al 0.01 Zr 0.004 Ti 0.004 W 0.002 O 2 .
  • the nickel-rich layered oxide material prepared in this example was characterized.
  • the results showed that the secondary particles were spherical in shape, the average particle size D 50 was 15.0 ⁇ m, the specific surface area was 0.33 m 2 /g, and the concentrations of Zr, Ti, and W within 50 nm of the primary particle surface were much higher than those at the center of the primary particle.
  • the stirring speed of the mixed solution in the reactor is set to 1000 r/min, and the reaction temperature is 50 ⁇ 1°C. After the reaction is continued for 20 hours, the obtained precipitate is discharged, washed with deionized water, and dried at a drying temperature of 180°C to obtain a hydroxide precursor X.
  • the hydroxide precursor X, 769.6 g of Li 2 CO 3 , 17.7 g of SrCO 3 , 19.7 g of Yb 2 O 3 and 8.8 g of Ta 2 O 5 were fully mixed in a high-speed mixer to obtain a mixture Y.
  • the mixture Y is placed in an oxygen atmosphere furnace for step-by-step roasting.
  • Oxygen is continuously introduced into the furnace during the whole roasting process.
  • the specific process is: firstly, the temperature is raised to 600°C for roasting for 4 hours (the heating rate is 4°C/min, and the oxygen intake rate is 5m3 /h), then the temperature is raised to 890°C for roasting for 3 hours (the heating rate is 4°C/min, and the oxygen intake rate is 2m3 /h), and then the temperature is lowered to 800°C for roasting for 11 hours (the cooling rate is 6°C/min, and the oxygen intake rate is 4m3 /h).
  • the furnace is cooled, and then the product is crushed and sieved to obtain a nickel-rich layered oxide with a chemical formula of LiNi 0.818 Sr 0.006 Co 0.060 Yb 0.005 Mn 0.109 Ta 0.002 O 2 .
  • the nickel-rich layered oxide material prepared in this example was characterized. The results showed that the morphology was monodispersed primary particles, the median particle size D 50 was 3.2 ⁇ m, the specific surface area was 0.70 m 2 /g, and the concentrations of Yb and Ta elements within 50 nm of the primary particle surface were much higher than those at the center of the primary particles.
  • agent solution IV deionized water is added into the reactor as the base liquid, and solutions I, II, III, and IV are simultaneously pumped into the reactor for complexation and precipitation reactions, and the flow rates of the NaOH solution and the ammonia complexing agent solution are controlled so that the pH of the mixed reaction liquid in the reactor is always maintained within the range of 11.0 ⁇ 0.05.
  • the stirring speed of the mixed solution in the reactor is set to 1000r/min, and the reaction temperature is 55 ⁇ 1°C. After the reaction is continued for 60h, the obtained precipitate is discharged, washed with deionized water and dried at a drying temperature of 140°C to obtain a hydroxide precursor X.
  • hydroxide precursor X 873.6 g of LiOH, 5.9 g of NiO, 15.6 g of Al(OH) 3 and 14.6 g of ZrO 2 were fully mixed using a high-speed mixer to obtain a mixture Y.
  • the mixture Y is placed in an oxygen atmosphere furnace for step-by-step roasting.
  • Oxygen is continuously introduced into the furnace during the whole roasting process.
  • the specific process is: firstly, the temperature is raised to 580°C for roasting for 5h (the heating rate is 3°C/min, and the oxygen intake rate is 4m3 /h), then the temperature is raised to 780°C for roasting for 2h (the heating rate is 3°C/min, and the oxygen intake rate is 6m3 /h), and then the temperature is lowered to 750°C for roasting for 12h (the cooling rate is 3°C/min, and the oxygen intake rate is 3m3 /h).
  • the furnace is cooled, and then the product is crushed and sieved to obtain nickel-rich layered oxide with the chemical formula of LiNi 0.9 Ni 2+ 0.004 Co 0.039 Al 0.01 Mn 0.039 Zr 0.006 W 0.002 O 2 .
  • the nickel-rich layered oxide material prepared in this example was characterized.
  • the results showed that the secondary particles were spherical in shape, the average particle size D 50 was 12.0 ⁇ m, the specific surface area was 0.46 m 2 /g, and the concentrations of Zr and W elements within 50 nm of the primary particle surface were much higher than those at the center of the primary particle.
  • the stirring speed of the mixed solution in the reactor was set to 900 r/min, and the reaction temperature was 56 ⁇ 1°C. After the reaction was continued for 48 hours, the obtained precipitate was discharged, washed with deionized water, and dried at a drying temperature of 160°C to obtain a hydroxide precursor X.
  • hydroxide precursor X 873.6 g of LiOH, 16.8 g of MgCO 3 , 15.6 g of Al(OH) 3 and 6.5 g of Sb 2 O 5 were fully mixed in a high-speed mixer to obtain a mixture Y.
  • the mixture Y is placed in an oxygen atmosphere furnace for step-by-step roasting.
  • Oxygen is continuously introduced into the furnace during the whole roasting process.
  • the specific process is: firstly, the temperature is raised to 520°C for roasting for 5h (the heating rate is 5°C/min, and the oxygen intake rate is 3m3 /h), then the temperature is raised to 770°C for roasting for 5h (the heating rate is 3°C/min, and the oxygen intake rate is 5m3 /h), and then the temperature is lowered to 740°C for roasting for 10h (the cooling rate is 5°C/min, and the oxygen intake rate is 3m3 /h).
  • the furnace is cooled, and then the product is crushed and sieved to obtain nickel-rich layered oxide with a chemical formula of LiNi 0.943 Mg 0.01 Al 0.01 Mn 0.02 Zr 0.007 Ti 0.008 Sb 0.002 O 2 .
  • the nickel-rich layered oxide material prepared in this example was characterized.
  • the results showed that the secondary particles were spherical in shape, the average particle size D 50 was 10.5 ⁇ m, the specific surface area was 0.42 m 2 /g, and the concentrations of Zr, Ti, and Sb within 50 nm of the primary particle surface were much higher than those at the center of the primary particle.
  • Example 1 The preparation method of Example 1 is referred to, except that: the mixture Y is placed in an oxygen atmosphere furnace for calcination, the temperature is raised to 780°C and maintained for 18 hours, the heating rate is 3 ° C/min, and the air intake rate is 4m3 /h; finally , a nickel - rich layered oxide material is prepared, and the chemical formula is approximately LiNi0.874Sr0.0045Co0.058Al0.015Mn0.0388Zr0.0078W0.0019O2 .
  • the electrochemical performance of the oxide materials prepared in Examples 1 to 7 and Comparative Examples 1 to 3 as positive electrode materials of lithium secondary batteries was tested in button-type lithium secondary batteries.
  • the specific preparation method of the lithium secondary battery and its positive electrode sheet was as follows: the prepared positive electrode material powder was mixed with acetylene black and polyvinylidene fluoride in a mass ratio of 90:5:5, an appropriate amount of N-methylpyrrolidone was added as a dispersant, and the mixture was ground into a slurry; then the slurry was evenly coated on an aluminum foil, vacuum dried at 120° C.

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Abstract

本申请提供一种富镍层状氧化物材料及其制备方法和应用。本申请提供的富镍层状氧化物材料的晶体结构为六方相R-3m空间群，晶格微观应变量≤0.25％。

Description

富镍层状氧化物材料及其制备方法和应用
相关申请
本申请要求2022年12月20日申请的，申请号为202211638989.X，名称为“一种富镍层状氧化物材料及其制备方法和应用”的中国专利申请的优先权，在此将其全文引入作为参考。
技术领域
本申请属于电池材料领域，尤其涉及一种富镍层状氧化物材料及其制备方法和应用。
背景技术
近年来新能源汽车的快速发展对锂二次电池的能量密度、循环寿命和功率密度提出了更高的要求，而正极材料是锂二次电池性能突破的关键因素。LiNiO2材料具有高比容量，资源丰富，成本低等优势，但存在Li+/Ni2+阳离子混排，非化学计量比以及高脱锂态安全性问题等明显的缺陷，阻碍了其实际应用。研究者通过引入Co、Mn、Al、Mg、Ti等金属离子部分取代Ni3+，形成二元或三元层状氧化物，提高材料的结构稳定性和循环性能，其中灵活调控Co和Mn的比例，平衡材料组分和电化学性能，构筑了更高能量密度的富镍NCM或NCA三元正极材料。然而，富镍三元正极材料在循环过程中，H2-H3相变产生的一次颗粒各向异性收缩和膨胀会加剧材料内部的应力，诱发材料内部微裂纹的产生与扩展，进而导致一次颗粒间的分离和粉化，加速电解液与微裂纹之间的副反应，最终导致材料失效。
发明内容
本申请提供了一种富镍层状氧化物材料，所述富镍层状氧化物材料的晶体结构为六方相R-3m空间群，晶格微观应变量≤0.25％。
一些实施例中，所述富镍层状氧化物材料的化学通式为：LiNixAaBbCcDdO2，其中，Ni为+3价，A为+2价金属阳离子，B为+3价金属阳离子，C为+4价金属阳离子，D为+5价及以上金属阳离子，0.8≤x＜1，a>0，b>0，c>0，d≥0，且x+a+b+c+d＝1。
一些实施例中，所述富镍层状氧化物材料为颗粒形式。所述B、C和D所包含的所有种类金属阳离子中，至少有两种金属阳离子在所述富镍层状氧化物材料的一次颗粒表面处 的浓度大于一次颗粒中心处。
一些实施例中，所述A为Mg2+、Ni2+和Sr2+中的一种或多种；所述B为Al3+、Co3+、Ga3+、Y3+、La3+和Yb3+中的一种或多种；所述C为Mn4+、Zr4+、Ti4+、Sn4+和Ce4+中的一种或多种；所述D为V5+、Nb5+、Sb5+、Ta5+、Mo6+和W6+中的一种或多种。
一些实施例中，所述富镍层状氧化物材料满足以下条件中的至少一个条件：
所述富镍层状氧化物材料的D50粒径为2～20μm；
所述富镍层状氧化物材料的比表面积为0.2～2m2/g；
所述富镍层状氧化物材料的形貌为一次颗粒或球形二次颗粒。
本申请提供了一种富镍层状氧化物材料的制备方法，包括以下步骤：
a)将溶液I、溶液II、氢氧化钠和络合剂混合并进行络合与沉淀反应，在反应过程中控制所述氢氧化钠和络合剂的用量使混合体系的pH值维持在10～13，得到氢氧化物沉淀；
步骤a)中，所述溶液I的成分包括镍源化合物和水；所述溶液II的成分包括第一金属源化合物和水；所述第一金属源化合物为C源化合物和D源化合物中的至少一种，或者为C源化合物和D源化合物中至少一种与A源化合物和B源化合物中至少一种的混合物；所述A源化合物为+2价金属阳离子所对应的水溶性金属盐，所述B源化合物为+3价金属阳离子所对应的水溶性金属盐，所述C源化合物为+4价金属阳离子所对应的水溶性金属盐，所述D源化合为+5价及以上金属阳离子所对应的水溶性金属盐；
b)将所述氢氧化物沉淀、锂源化合物和第二金属源化合物混合，得到混合料；
步骤b)中，所述第二金属源化合物为A源化合物、B源化合物、C源化合物和D源化合物中的一种或多种；
c)将所述混合料在含氧气氛中进行分步焙烧，得到富镍层状氧化物材料；所述富镍层状氧化物材料的晶体结构为六方相R-3m空间群，晶格微观应变量≤0.25％。
一些实施例中，步骤a)中，所述溶液I中金属离子的浓度为1～5mol/L；所述溶液II中金属离子的总浓度为0.5～5mol/L。
一些实施例中，步骤a)中，所述氢氧化钠以氢氧化钠水溶液的形式参与混合，所述氢氧化钠水溶液的浓度为0.5～4mol/L；所述络合剂为氨水、乙二胺四乙酸和乙二胺中的一种或多种，所述络合剂以络合剂水溶液的形式参与混合，所述络合剂水溶液的浓度为0.5～10mol/L。
一些实施例中，步骤a)中，所述络合与沉淀反应在搅拌条件下进行，搅拌速率为200～1000r/min；所述络合与沉淀反应的温度为30～70℃；所述络合与沉淀反应的时间为10～50h。
一些实施例中，步骤c)中，所述分步焙烧的具体过程包括：
i)从环境温度升温至第一焙烧温度，进行一次保温焙烧；
所述第一焙烧温度为300～600℃；升温至所述第一焙烧温度的升温速率为1～6℃/min；所述一次保温焙烧的时间为4～10h；
ii)继续升温至第二焙烧温度，进行二次保温焙烧；
所述第二焙烧温度为700～1000℃；升温至所述第二焙烧温度的升温速率为1～6℃/min；所述二次保温焙烧的时间为1～5h；
iii)调温至第三焙烧温度，进行三次保温焙烧；
所述第三焙烧温度为700～900℃，且第三焙烧温度小于或等于第二焙烧温度；调温至所述第三焙烧温度的速率为0～10℃/min；所述三次保温焙烧的时间为10～20h。
一些实施例中，所述分步焙烧的过程中持续向所用焙烧设备中通入氧气以提供焙烧所需的含氧气氛；步骤i)的氧气进气速率为0.5～5m3/h，步骤ii)的氧气进气速率为0.5～5m3/h，步骤iii)的氧气进气速率为0.5～5m3/h。
一些实施例中，所述第一金属源化合物包括A源化合物、B源化合物、C源化合物和任选地D源化合物。
一些实施例中，所述第二金属源化合物中的A源化合物、B源化合物、C源化合物或D源化合物为+2价金属阳离子、+3价金属阳离子、+4价金属阳离子或+5价金属阳离子的碳酸盐、氢氧化物或氧化物。
本申请提供了一种锂离子二次电池，所述锂离子二次电池的正极材料包括上述技术方案所述的富镍层状氧化物材料或上述技术方案所述制备方法制得的富镍层状氧化物材料。
本申请提供了一种用电装置，所述用电装置安装有上述技术方案所述的锂离子二次电池。
与现有技术相比，本申请提供了一种富镍层状氧化物材料及其制备方法和应用。本申请提供的富镍层状氧化物材料的晶体结构为六方相R-3m空间群，晶格微观应变量≤0.25％。本申请通过多价态、多种类金属阳离子的高熵体系设计，结合前驱体(氢氧化物沉淀)组分和煅烧制式的优化，利用高熵组分在煅烧过程中的迟滞扩散效应，调控材料内部元素分布，诱导颗粒以低应力方向生长，降低了本体材料晶体结构中的微观应变强度。本发明申请提供的富镍层状氧化物材料具有较低的微观应变量，在高电位下具备良好的结构稳定性和安全性。
附图说明
为了更清楚地说明本申请实施例或传统技术中的技术方案，下面将对实施例或传统技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据公开的附图获得其他的附图。
图1为本申请提供的实施例1富镍层状氧化物材料的SEM图；
图2是本申请提供的实施例1富镍层状氧化物材料中Zr、W元素在一次颗粒表面不同深度的分布图；
图3是本申请提供的实施例1富镍层状氧化物的XRD及其LeBail结构精修图；
图4是本申请提供的实施例1与对比例1～3所制备的氧化物材料的Williamson-Hall图；
图5为本申请提供的实施例1与对比例1～3所制备的氧化物材料在锂二次电池测试中的循环性能对比图。
具体实施方式
下面对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
高熵材料是一类含有5种及以上元素，并以等摩尔或近摩尔比相互固溶而得到的单一相材料，在热力学、动力学、微观结构和性能等方面表现出独特的效应，例如高熵效应、迟滞扩散效应、晶格畸变效应等。本申请结合高熵材料的性能优势来优化正极材料的结构特征，开发出了在高电位下具有良好结构稳定性和安全性的锂电池正极材料。
本申请提供了一种富镍层状氧化物材料及其制备方法和应用，其所要解决的核心技术问题在于：富镍层状氧化物正极材料在高电位下由于H2-H3相变，导致材料的结构稳定性差，安全性差。本申请通过多价态、多种类金属阳离子的高熵体系设计，结合前驱体组分和煅烧制式的优化，利用高熵组分在煅烧过程中的迟滞扩散效应，调控材料内部元素分布，诱导颗粒以低应力方向生长，降低了本体材料晶体结构中的微观应变强度，从而减轻材料在高电位下的应力累积，提高结构稳定性和安全性。
需要说明的是，本申请技术方案与传统的金属离子掺杂的富镍层状氧化物材料相比，其关键区别在于，传统单金属离子或多金属离子掺杂，通常以较高的金属-氧键能提升晶体结构的稳定性；而本申请中富镍层状氧化物则是通过引入多价态、多种类金属阳离子形成富镍高熵固溶体，优化前驱体组分和煅烧制式，利用高熵组分在煅烧过程中的特殊效应(迟滞扩散效应)降低材料晶体结构中的微观应变，从而缓解高电位下的应力累积，实现电化 学性能和安全性的提升。
为实现上述目的，本申请具体提出如下技术方案：
本申请提供了一种富镍层状氧化物材料，其晶体结构为六方相R-3m空间群，晶格微观应变量≤0.25％。在本申请中，所述晶格微观应变量具体可为0.05％、0.08％、0.14％、0.16％、0.19％或0.22％。
所述富镍层状氧化物材料的化学通式可以为：LiNixAaBbCcDdO2；其中，Ni为+3价；A为+2价金属阳离子，例如为Mg2+、Ni2+和Sr2+中的一种或多种；B为+3价金属阳离子，例如为Al3+、Co3+、Ga3+、Y3+、La3+和Yb3+中的一种或多种；C为+4价金属阳离子，例如为Mn4+、Zr4+、Ti4+、Sn4+和Ce4+中的一种或多种；D为+5价及以上金属阳离子，例如为V5+、Nb5+、Sb5+、Ta5+、Mo6+和W6+中的一种或多种；0.8≤x＜1，a>0，b>0，c>0，d≥0，且x+a+b+c+d＝1。
所述富镍层状氧化物材料可以为颗粒形式。在一些实施例中，所述B、C和D所包含的所有种类金属阳离子中，至少有两种金属阳离子在所述富镍层状氧化物材料的一次颗粒的表面处的浓度大于所述一次颗粒的中心处。在本申请中，一次颗粒中两种及以上金属阳离子的浓度梯度，可通过协同效应稳定材料表面结构，抑制高电位下氧的流失，提升材料电化学稳定性。
在本申请提供的富镍层状氧化物材料中，一次颗粒表面处的浓度大于一次颗粒中心处的所述至少两种金属阳离子既可以是同价态的金属阳离子，也可以是不同价态的金属阳离子，本申请不做特别限定。
所述富镍层状氧化物材料的D50粒径可以为2～20μm，例如为2μm、3μm、3.2μm、4μm、5μm、6μm、7μm、8μm、9μm、10μm、10.2μm、10.5μm、11μm、12μm、12.5μm、13μm、14μm、15μm、16μm、17μm、18μm、19μm或20μm。
所述富镍层状氧化物材料的比表面积可以为0.2～2m2/g，例如为0.2m2/g、0.25m2/g、0.3m2/g、0.33m2/g、0.35m2/g、0.4m2/g、0.42m2/g、0.45m2/g、0.46m2/g、0.5m2/g、0.55m2/g、0.6m2/g、0.7m2/g、0.76m2/g、0.8m2/g、0.9m2/g、1m2/g、1.1m2/g、1.2m2/g、1.3m2/g、1.4m2/g、1.5m2/g、1.6m2/g、1.7m2/g、1.8m2/g、1.9m2/g或2m2/g。
所述富镍层状氧化物材料的形貌可以为一次颗粒或球形二次颗粒。
在本申请提供的一些实施例中，所述富镍层状氧化物材料的化学式为以下化学式中的任一种：
LiNi0.874Sr0.0045Co0.058Al0.015Mn0.0388Zr0.0078W0.0019O2；
LiNi0.814Mg0.003Co0.108Al0.01Mn0.058Ti0.0048Ta0.0022O2；
LiNi3+ 0.905Ni2+ 0.004Co0.059Y0.005Mn0.019Zr0.0058Nb0.0022O2；
LiNi0.867Mg0.005Co0.108Al0.01Zr0.004Ti0.004W0.002O2；
LiNi0.818Sr0.006Co0.060Yb0.005Mn0.109Ta0.002O2；
LiNi3+ 0.9Ni2+ 0.004Co0.039Al0.01Mn0.039Zr0.006W0.002O2；
LiNi0.943Mg0.01Al0.01Mn0.02Zr0.007Ti0.008Sb0.002O2。
本申请还提供了一种上述技术方案所述的富镍层状氧化物材料的制备方法，包括以下步骤：
a)将溶液I、溶液II、氢氧化钠和络合剂混合并进行络合与沉淀反应，在反应过程中控制所述氢氧化钠和络合剂的用量使混合体系的pH值维持在10～13，得到氢氧化物沉淀；
b)将所述氢氧化物沉淀、锂源化合物和第二金属源化合物混合，得到混合料；
c)将所述混合料在含氧气氛中进行分步焙烧，得到富镍层状氧化物材料。
在本申请提供的制备方法中，步骤a)中，所述溶液I的成分包括镍源化合物和水；所述镍源化合物为镍的可溶性盐，例如为镍的硫酸盐、氯化物和硝酸盐中的一种或多种；所述溶液I中金属离子的浓度可以为1～5mol/L，例如可为1mol/L、1.5mol/L、2mol/L、2.5mol/L、3mol/L、3.5mol/L、4mol/L、4.5mol/L或5mol/L。
在本申请提供的制备方法中，步骤a)中，所述溶液II的成分包括第一金属源化合物和水；所述第一金属源化合物为C源化合物和D源化合物中的至少一种，或者为C源化合物和D源化合物中至少一种与A源化合物和B源化合物中至少一种的混合物。在本申请中，所述A源化合物、B源化合物、C源化合物和D源化合物分别为上文所介绍的+2价金属阳离子A、+3价金属阳离子B、+4价金属阳离子C和+5价及以上金属阳离子D所对应的水溶性金属盐，所述水溶性金属盐中的金属元素与对应金属阳离子一致，价态可以相同，也可以不同，不做特别限定。在本申请中，所述溶液II中金属离子的总浓度优选为0.5～5mol/L，具体可为0.5mol/L、1mol/L、1.5mol/L、2mol/L、2.5mol/L、3mol/L、3.5mol/L、4mol/L、4.5mol/L或5mol/L。
在一些实施例中，所述第一金属源化合物包括A源化合物、B源化合物和C源化合物。
在一些实施例中，所述第一金属源化合物包括A源化合物、B源化合物、C源化合物和D源化合物。
在本申请提供的制备方法中，步骤a)中，所述氢氧化钠可以氢氧化钠水溶液的形式参与混合。所述氢氧化钠水溶液的浓度可为0.5～4mol/L，例如可为0.5mol/L、1mol/L、1.5mol/L、2mol/L、2.5mol/L、3mol/L、3.5mol/L或4mol/L。
在本申请提供的制备方法中，步骤a)中，所述络合剂可为氨水、乙二胺四乙酸和乙 二胺中的一种或多种。所述络合剂可以络合剂水溶液的形式参与混合。所述络合剂水溶液的浓度可为0.5～10mol/L，例如可为0.5mol/L、1mol/L、1.5mol/L、2mol/L、2.5mol/L、3mol/L、3.5mol/L、4mol/L、4.5mol/L、5mol/L、5.5mol/L、6mol/L、6.5mol/L、7mol/L、7.5mol/L、8mol/L、8.5mol/L、9mol/L、9.5mol/L或10mol/L。
在本申请提供的制备方法中，步骤a)中，所述混合优选在添加有水作为底液的反应釜中进行。所述混合体系的pH值具体可维持在10、10.1、10.2、10.3、10.4、10.5、10.6、10.7、10.8、10.9、11、11.1、11.2、11.3、11.4、11.5、11.6、11.7、11.8、11.9、12、12.1、12.2、12.3、12.4、12.5、12.7、12.8、12.9或13。所述络合与沉淀反应可在搅拌的条件下进行。搅拌速率可为200～1000r/min，例如为200r/min、250r/min、300r/min、350r/min、400r/min、450r/min、500r/min、550r/min、600r/min、650r/min、700r/min、750r/min、800r/min、850r/min、900r/min、950r/min或1000r/min。所述络合与沉淀反应的温度可为30～70℃，例如为30℃、35℃、40℃、45℃、50℃、55℃、56℃、60℃、65℃或70℃。所述络合与沉淀反应的时间可为10～50h，例如为10h、15h、20h、25h、30h、35h、40h、42h、45h或50h。
在本申请提供的制备方法中，步骤a)中，可对得到的氢氧化物沉淀进行洗涤和干燥。所述干燥的温度可为100～300℃，例如为100℃、110℃、120℃、130℃、140℃、150℃、160℃、170℃、180℃、190℃、200℃、210℃、220℃、230℃、240℃、250℃、260℃、270℃、280℃、290℃或300℃。
在本申请提供的制备方法中，步骤b)中，所述锂源化合物可为LiOH，Li2CO3、Li2SO4、LiCl和LiNO3中的一种或多种。所述第二金属源化合物为A源化合物、B源化合物、C源化合物和D源化合物中的一种或多种。
在一些实施例中，所述第二金属源化合物中的A源化合物、B源化合物、C源化合物或D源化合物可与所述所述第一金属源化合物中的A源化合物、B源化合物、C源化合物或D源化合物不同。
在一些实施例中，所述第二金属源化合物中的A源化合物、B源化合物、C源化合物或D源化合物可为A、B、C或D的碳酸盐、氢氧化物或氧化物。
在本申请提供的制备方法中，步骤c)中，所述含氧气氛包括但不限于空气和纯氧，例如为纯氧。
在本申请提供的制备方法中，步骤c)中，所述分步焙烧可包括：
i)从环境温度升温至第一焙烧温度，进行一次保温焙烧；
ii)继续升温至第二焙烧温度，进行二次保温焙烧；
iii)调温至第三焙烧温度，进行三次保温焙烧。
在本申请提供的上述焙烧过程中，步骤i)中，所述第一焙烧温度可为300～600℃，例如为300℃、310℃、320℃、330℃、340℃、350℃、360℃、370℃、380℃、390℃、400℃、410℃、420℃、430℃、440℃、450℃、460℃、470℃、480℃、490℃、500℃、510℃、520℃、530℃、540℃、550℃、560℃、570℃、580℃、590℃或600℃。升温至所述第一焙烧温度的升温速率可为1～6℃/min，例如为1℃/min、1.5℃/min、2℃/min、2.5℃/min、3℃/min、3.5℃/min、4℃/min、4.5℃/min、5℃/min、5.5℃/min或6℃/min。所述一次保温焙烧的时间可为4～10h，例如为4h、4.5h、5h、5.5h、6h、6.5h、7h、7.5h、8h、8.5h、9h、9.5h或10h。
在本申请提供的上述焙烧过程中，步骤ii)中，所述第二焙烧温度可为700～1000℃，例如为700℃、710℃、720℃、730℃、740℃、750℃、760℃、770℃、780℃、790℃、800℃、810℃、820℃、830℃、840℃、850℃、860℃、870℃、880℃、890℃、900℃、910℃、920℃、930℃、940℃、950℃、960℃、970℃、980℃、990℃或1000℃。升温至所述第二焙烧温度的升温速率可为1～6℃/min，例如为1℃/min、1.5℃/min、2℃/min、2.5℃/min、3℃/min、3.5℃/min、4℃/min、4.5℃/min、5℃/min、5.5℃/min或6℃/min。所述二次保温焙烧的时间可为1～5h，例如为1h、1.5h、2h、2.5h、3h、3.5h、4h、4.5h或5h。
在本申请提供的上述焙烧过程中，步骤iii)中，所述第三焙烧温度可为700～900℃，例如为700℃、710℃、720℃、730℃、740℃、750℃、760℃、770℃、780℃、790℃、800℃、810℃、820℃、830℃、840℃、850℃、860℃、870℃、880℃、890℃或900℃，且所述第三焙烧温度≤第二焙烧温度。调温至所述第三焙烧温度的速率可为0～10℃/min，例如为0(即，不进行调温)、0.5℃/min、1℃/min、1.5℃/min、2℃/min、2.5℃/min、3℃/min、3.5℃/min、4℃/min、4.5℃/min、5℃/min、5.5℃/min、6℃/min、6.5℃/min、7℃/min、7.5℃/min、8℃/min、8.5℃/min、9℃/min、9.5℃/min或10℃/min。所述三次保温焙烧的时间可为10～20h，例如为10h、10.5h、11h、11.5h、12h、12.5h、13h、13.5h、14h、14.5h、15h、15.5h、16h、16.5h、17h、17.5h、18h、18.5h、19h、19.5h或20h。
在本申请提供的上述焙烧过程中，所述分步焙烧的过程中可持续向所用焙烧设备中通入氧气以提供焙烧所需的含氧气氛。其中，步骤i)的氧气进气速率可为0.5～5m3/h，例如为0.5m3/h、1m3/h、1.5m3/h、2m3/h、2.5m3/h、3m3/h、3.5m3/h、4m3/h、4.5m3/h或5m3/h。步骤ii)的氧气进气速率可为0.5～5m3/h，例如为0.5m3/h、1m3/h、1.5m3/h、2m3/h、2.5m3/h、3m3/h、3.5m3/h、4m3/h、4.5m3/h或5m3/h。步骤iii)的氧气进气速率可为0.5～5m3/h，例如为0.5m3/h、1m3/h、1.5m3/h、2m3/h、2.5m3/h、3m3/h、3.5m3/h、4m3/h、4.5m3/h或5m3/h。
在本申请提供的制备方法中，所述焙烧结束后，可将得到的产物冷却后进行粉碎和过 筛。
本申请还提供了一种锂离子二次电池，包括正极、负极、电解液和介于正极与负极之间的隔膜；其中，所述正极的材料包括上述技术方案所述的富镍层状氧化物材料或上述技术方案所述制备方法制得的富镍层状氧化物材料。
本申请还提供了一种用电装置，所述用电装置安装有上述技术方案所述的锂离子二次电池。
为更清楚起见，下面通过以下实施例和对比例进行详细说明。
实施例1
称取4594.6g的NiSO4溶解于去离子水中配制成2mol/L的盐溶液I，称取326.1g的CoSO4、24.6g的NaAlO2、173.1g的MnSO4、55.4g的Zr(SO4)2和10.2g的钨酸铵溶解于去离子水中配制金属离子浓度1mol/L的高熵元素溶液Ⅱ，配制浓度为1.5mol/L的NaOH溶液III和浓度为2.0mol/L的氨水络合剂溶液IV；在反应釜中加入去离子水作为底液，将溶液I、II、III、IV同时泵入反应釜中进行络合与沉淀反应，控制NaOH溶液和氨水络合剂溶液的流速，使反应釜中混合反应液的pH始终保持在11.2±0.05的范围内，反应釜内混合溶液搅拌速度设置为800r/min，反应温度为50±1℃，持续反应40h后，将得到的沉淀物排出，去离子水洗涤并烘干，烘干温度为150℃，得到氢氧化物前驱体X。
将上述氢氧化物前驱体X、873.6g的LiOH和10.9g的Sr(OH)2采用高混机进行充分混合，得到混合物Y。
将上述混合物Y放置于氧气气氛炉中进行分步焙烧，焙烧全过程中持续向炉内通入氧气，具体过程为：首先升温至550℃焙烧4h(升温速率为3℃/min，氧气进气速率为3m3/h)，然后升温至800℃焙烧1h(升温速率为3℃/min，氧气进气速率为4m3/h)，之后降温至780℃焙烧14h(降温速率为4℃/min，氧气进气速率为3m3/h)。
焙烧结束后，随炉冷却，然后将产物进行粉碎，过筛，得到富镍层状氧化物材料，化学式为LiNi0.874Sr0.0045Co0.058Al0.015Mn0.0388Zr0.0078W0.0019O2。
对本实施例制备的富镍层状氧化物材料进行扫描电镜(SEM)观察，结果如图1所示，图1为本申请提供的实施例1富镍层状氧化物材料的SEM图。通过图1可以看出，该材料具有光滑的表面，是由一次颗粒(D50粒径约400nm)团聚而成的球形二次颗粒，二次颗粒的粒径约12.8μm。
对本实施例制备的富镍层状氧化物材料进行D50粒径和比表面积检测，结果为：中粒径D50为12.5μm，比表面积为0.45m2/g。
采用飞行时间二次离子质谱仪器(ToF-SIMS)检测对本实施例制备的富镍层状氧化物 材料不同深度的金属离子浓度进行检测，溅射速率设置为0.15nm/s。实验结果如图2所示，图2是本申请提供的实施例1富镍层状氧化物材料中Zr、W元素在一次颗粒表面不同深度的分布图。通过图2可以看出，Zr和W元素在一次颗粒表面深度50nm以内的浓度远高于一次颗粒中心处的浓度。
对本实施例制备的富镍层状氧化物材料进行X射线衍射(XRD)测试，XRD测试采用的Cu-Kα靶，发射波长λ＝0.1548nm，扫描电压为40kV，电流为40mA，使用步进扫描方式，步进宽度为0.01°，步进时间为3秒，扫描范围为10°～80°。实验结果如图3所示，图3是本申请提供的实施例1富镍层状氧化物的XRD及其LeBail结构精修图。通过图3可以看出，该材料的衍射峰对应于六方层状结构，R-3m空间群。
实施例2
称取3869.6g的NiCl2溶解于去离子水中配制成2.5mol/L的盐溶液I，称取607.2g的CoSO4、258.7g的MnSO4和18.2g的TiCl4溶解于去离子水中配制金属离子浓度0.5mol/L的高熵元素溶液Ⅱ，配制浓度为2.0mol/L的NaOH溶液III和浓度为2.5mol/L的氨水络合剂溶液IV；在反应釜中加入去离子水作为底液，将溶液I、II、III、IV同时泵入反应釜中进行络合与沉淀反应，控制NaOH溶液和氨水络合剂溶液的流速，使反应釜中混合反应液的pH始终保持在12.0±0.05的范围内，反应釜内混合溶液搅拌速度设置为800r/min，反应温度为55±1℃，持续反应36h后，将得到的沉淀物排出，去离子水洗涤并烘干，烘干温度为150℃，得到氢氧化物前驱体X。
将上述氢氧化物前驱体X、769.6g的Li2CO3、5g的MgCO3、15.6g的Al(OH)3和9.7g的Ta2O5采用高混机进行充分混合，得到混合物Y。
将上述混合物Y放置于氧气气氛炉中进行分步焙烧，焙烧全过程中持续向炉内通入氧气，具体过程为：首先升温至500℃焙烧6h(升温速率为4℃/min，氧气进气速率为2m3/h)，然后升温至820℃焙烧2h(升温速率为4℃/min，氧气进气速率为5m3/h)，之后降温至810℃焙烧10h(降温速率为5℃/min，氧气进气速率为3m3/h)。
焙烧结束后，随炉冷却，然后将产物进行粉碎，过筛，得到富镍层状氧化物，化学式为LiNi0.814Mg0.003Co0.108Al0.01Mn0.058Ti0.0048Ta0.0022O2。
对本实施例制备的富镍层状氧化物材料进行表征，结果为：形貌为球形二次颗粒，中粒径D50为10.2μm，比表面积为0.55m2/g，Ti、Ta元素在材料一次颗粒表面深度50nm以内的浓度远高于一次颗粒中心处浓度。
实施例3
称取4778.6g的NiSO4溶解于去离子水中配制成4.0mol/L的盐溶液I，称取280.8g的 CoCl2、84.8g的MnSO4和41.2g的Zr(SO4)2溶解于去离子水中配制金属离子浓度2.5mol/L的高熵元素溶液Ⅱ，配制浓度为3.0mol/L的NaOH溶液III和浓度为5.0mol/L的EDTA络合剂溶液IV；在反应釜中加入去离子水作为底液，将溶液I、II、III、IV同时泵入反应釜中进行络合与沉淀反应，控制NaOH溶液和EDTA络合剂溶液的流速，使反应釜中混合反应液的pH始终保持在12.3±0.05的范围内，反应釜内混合溶液搅拌速度设置为1000r/min，反应温度为58±1℃，持续反应30h后，将得到的沉淀物排出，去离子水洗涤并烘干，烘干温度为180℃，得到氢氧化物前驱体X。
将上述氢氧化物前驱体X、873.6g的LiOH、11.3g的Y2O3和5.8g的Nb2O5采用高混机进行充分混合，得到混合物Y。
将上述混合物Y放置于氧气气氛炉中进行分步焙烧，焙烧全过程中持续向炉内通入氧气，具体过程为：首先升温至500℃焙烧6h(升温速率为4℃/min，氧气进气速率为2m3/h)，然后升温至850℃焙烧3h(升温速率为4℃/min，氧气进气速率为2m3/h)，之后降温至800℃焙烧11h(降温速率为5℃/min，氧气进气速率为2m3/h)。
焙烧结束后，随炉冷却，然后将产物进行粉碎，过筛，得到富镍层状氧化物，化学式为LiNi3+ 0.905Ni2+ 0.004Co0.059Y0.005Mn0.019Zr0.0058Nb0.0022O2。
对本实施例制备的富镍层状氧化物材料进行表征，结果为：形貌为单分散一次颗粒，中粒径D50为3.0μm，比表面积为0.76m2/g，Y、Zr、Nb元素在材料一次颗粒表面深度50nm以内的浓度远高于一次颗粒中心处浓度。
实施例4
称取4557.8g的NiSO4溶解于去离子水中配制成1.5mol/L的盐溶液I，称取513.9g的CoCl2、28.4g的Zr(SO4)2和15.2g的TiCl4溶解于去离子水中配制金属离子浓度3.0mol/L的高熵元素溶液Ⅱ，配制浓度为2.0mol/L的NaOH溶液III和浓度为6.0mol/L的氨水络合剂溶液IV；在反应釜中加入去离子水作为底液，将溶液I、II、III、IV同时泵入反应釜中进行络合与沉淀反应，控制NaOH溶液和氨水络合剂溶液的流速，使反应釜中混合反应液的pH始终保持在11.5±0.05的范围内，反应釜内混合溶液搅拌速度设置为600r/min，反应温度为55±1℃，持续反应50h后，将得到的沉淀物排出，去离子水洗涤并烘干，烘干温度为120℃，得到氢氧化物前驱体X。
将上述氢氧化物前驱体X、873.6g的LiOH、8.4g的MgCO3、10.2g的Al2O3和9.3g的WO3采用高混机进行充分混合，得到混合物Y。
将上述混合物Y放置于氧气气氛炉中进行分步焙烧，焙烧全过程中持续向炉内通入氧气，具体过程为：首先升温至550℃焙烧5h(升温速率为4℃/min，氧气进气速率为5m3/h)， 然后升温至760℃焙烧2h(升温速率为4℃/min，氧气进气速率为3m3/h)，之后维持760℃继续焙烧10h(氧气进气速率为3m3/h)。
焙烧结束后，随炉冷却，然后将产物进行粉碎，过筛，得到富镍层状氧化物，化学式为LiNi0.867Mg0.005Co0.108Al0.01Zr0.004Ti0.004W0.002O2。
对本实施例制备的富镍层状氧化物材料进行表征，结果为：形貌为球形二次颗粒，中粒径D50为15.0μm，比表面积为0.33m2/g，Zr、Ti、W元素在材料一次颗粒表面深度50nm以内的浓度远高于一次颗粒中心处浓度。
实施例5
称取3874.3g的NiCl2溶解于去离子水中配制成2.0mol/L的盐溶液I，称取331.7g的CoSO4和427.5g的MnCl2溶解于去离子水中配制金属离子浓度4.0mol/L的高熵元素溶液Ⅱ，配制浓度为1.5mol/L的NaOH溶液III和浓度为6.0mol/L的乙二胺络合剂溶液IV；在反应釜中加入去离子水作为底液，将溶液I、II、III、IV同时泵入反应釜中进行络合与沉淀反应，控制NaOH溶液和乙二胺络合剂溶液的流速，使反应釜中混合反应液的pH始终保持在12.5±0.05的范围内，反应釜内混合溶液搅拌速度设置为1000r/min，反应温度为50±1℃，持续反应20h后，将得到的沉淀物排出，去离子水洗涤并烘干，烘干温度为180℃，得到氢氧化物前驱体X。
将上述氢氧化物前驱体X、769.6g的Li2CO3、17.7g的SrCO3、19.7g的Yb2O3和8.8g的Ta2O5采用高混机进行充分混合，得到混合物Y。
将上述混合物Y放置于氧气气氛炉中进行分步焙烧，焙烧全过程中持续向炉内通入氧气，具体过程为：首先升温至600℃焙烧4h(升温速率为4℃/min，氧气进气速率为5m3/h)，然后升温至890℃焙烧3h(升温速率为4℃/min，氧气进气速率为2m3/h)，之后降温至800℃焙烧11h(降温速率为6℃/min，氧气进气速率为4m3/h)。
焙烧结束后，随炉冷却，然后将产物进行粉碎，过筛，得到富镍层状氧化物，化学式为LiNi0.818Sr0.006Co0.060Yb0.005Mn0.109Ta0.002O2。
对本实施例制备的富镍层状氧化物材料进行表征，结果为：形貌为单分散一次颗粒，中粒径D50为3.2μm，比表面积为0.70m2/g，Yb、Ta元素在材料一次颗粒表面深度50nm以内的浓度远高于一次颗粒中心处浓度。
实施例6
称取4278.4g的NiCl2溶解于去离子水中配制成3.0mol/L的盐溶液I，称取219.3g的CoSO4、154.4g的MnCl2和10.8g的钨酸铵溶解于去离子水中配制金属离子浓度1.0mol/L的高熵元素溶液Ⅱ，配制浓度为4.0mol/L的NaOH溶液III和浓度为8.0mol/L的氨水络合 剂溶液IV；在反应釜中加入去离子水作为底液，将溶液I、II、III、IV同时泵入反应釜中进行络合与沉淀反应，控制NaOH溶液和氨水络合剂溶液的流速，使反应釜中混合反应液的pH始终保持在11.0±0.05的范围内，反应釜内混合溶液搅拌速度设置为1000r/min，反应温度为55±1℃，持续反应60h后，将得到的沉淀物排出，去离子水洗涤并烘干，烘干温度为140℃，得到氢氧化物前驱体X。
将上述氢氧化物前驱体X、873.6g的LiOH、5.9g的NiO、15.6g的Al(OH)3和14.6g的ZrO2采用高混机进行充分混合，得到混合物Y。
将上述混合物Y放置于氧气气氛炉中进行分步焙烧，焙烧全过程中持续向炉内通入氧气，具体过程为：首先升温至580℃焙烧5h(升温速率为3℃/min，氧气进气速率为4m3/h)，然后升温至780℃焙烧2h(升温速率为3℃/min，氧气进气速率为6m3/h)，之后降温至750℃焙烧12h(降温速率3℃/min，氧气进气速率为3m3/h)。
焙烧结束后，随炉冷却，然后将产物进行粉碎，过筛，得到富镍层状氧化物，化学式为LiNi0.9Ni2+ 0.004Co0.039Al0.01Mn0.039Zr0.006W0.002O2。
对本实施例制备的富镍层状氧化物材料进行表征，结果为：形貌为球形二次颗粒，中粒径D50为12.0μm，比表面积为0.46m2/g，Zr、W元素在材料一次颗粒表面深度50nm以内的浓度远高于一次颗粒中心处浓度。
实施例7
称取4957.4g的NiSO4溶解于去离子水中配制成4.0mol/L的盐溶液I，称取89.2g的MnSO4、49.7g的Zr(SO4)2和30.3g的TiCl4溶解于去离子水中配制金属离子浓度1.0mol/L的高熵元素溶液Ⅱ，配制浓度为2.0mol/L的NaOH溶液III和浓度为6.0mol/L的EDTA络合剂溶液IV；在反应釜中加入去离子水作为底液，将溶液I、II、III、IV同时泵入反应釜中进行络合与沉淀反应，控制NaOH溶液和EDTA络合剂溶液的流速，使反应釜中混合反应液的pH始终保持在12.3±0.05的范围内，反应釜内混合溶液搅拌速度设置为900r/min，反应温度为56±1℃，持续反应48h后，将得到的沉淀物排出，去离子水洗涤并烘干，烘干温度为160℃，得到氢氧化物前驱体X。
将上述氢氧化物前驱体X、873.6g的LiOH、16.8g的MgCO3、15.6g的Al(OH)3和6.5g的Sb2O5采用高混机进行充分混合，得到混合物Y。
将上述混合物Y放置于氧气气氛炉中进行分步焙烧，焙烧全过程中持续向炉内通入氧气，具体过程为：首先升温至520℃焙烧5h(升温速率为5℃/min，氧气进气速率为3m3/h)，然后升温至770℃焙烧5h(升温速率为3℃/min，氧气进气速率为5m3/h)，之后降温至740℃焙烧10h(降温速率5℃/min，氧气进气速率为3m3/h)。
焙烧结束后，随炉冷却，然后将产物进行粉碎，过筛，得到富镍层状氧化物，化学式为LiNi0.943Mg0.01Al0.01Mn0.02Zr0.007Ti0.008Sb0.002O2。
对本实施例制备的富镍层状氧化物材料进行表征，结果为：形貌为球形二次颗粒，中粒径D50为10.5μm，比表面积为0.42m2/g，Zr、Ti、Sb元素在材料一次颗粒表面深度50nm以内的浓度远高于一次颗粒中心处浓度。
对比例1
按照摩尔比Ni/Co/Mn＝90:6:4的比例称取硫酸镍、硫酸钴、硫酸锰，并溶解于去离子水中配制成2mol/L的混合盐溶液I，配制浓度为1.5mol/L的NaOH溶液II和浓度为2.0mol/L的氨水络合剂溶液III；在反应釜中加入去离子水作为底液，将溶液I、II、III同时泵入反应釜中进行络合与沉淀反应，控制NaOH溶液和氨水络合剂溶液的流速，使反应釜中混合反应液的pH始终保持在11.2±0.05的范围内，反应釜内混合溶液搅拌速度设置为800r/min，反应温度为50±1℃，持续反应40h后，将得到的沉淀物排出，去离子水洗涤并烘干，烘干温度为150℃，得到锰镍钴氢氧化物前驱体X。
将上述锰镍钴氢氧化物前驱体X和873.6g的LiOH采用高混机进行充分混合，得到混合物Y。
将上述混合物Y放置于氧气气氛炉中进行分步焙烧，焙烧全过程中持续向炉内通入氧气，具体过程为：首先升温至550℃焙烧6h(升温速率为3℃/min，氧气进气速率为3m3/h)，然后升温至800℃焙烧1h(升温速率为3℃/min，氧气进气速率为4m3/h)，之后降温至780℃持续保温14h(降温速率为4℃/min，氧气进气速率为3m3/h)。
焙烧结束后，随炉冷却，然后将产物进行粉碎，过筛，得到富镍层状氧化物材料，化学式为LiNi0.90Co0.06Mn0.04O2。
对本对比例制备的富镍层状氧化物材料进行表征，结果为：形貌为球形二次颗粒，中粒径D50为13.2μm，比表面积为0.39m2/g。
对比例2
参照对比例1的制备方法，其区别在于：在制备混合物Y的过程中，将锰镍钴氢氧化物前驱体X、873.6g的LiOH、10.9g的Sr(OH)2、23.4g的Al(OH)3、19.0g的ZrO2和10.2g的钨酸铵采用高混机进行充分混合，得到混合物Y；最终制备获得了多组分掺杂的富镍层状氧化物材料，化学式近似为LiNi0.874Sr0.0045Co0.058Al0.015Mn0.0388Zr0.0078W0.0019O2。
对本对比例制备的多组分掺杂的富镍层状氧化物材料进行表征，结果为：形貌为球形二次颗粒，中粒径D50为13.0μm，比表面积为0.42m2/g，Zr、W元素在球形二次颗粒表面呈岛状偏析，在一次颗粒中未检测出Zr、W元素。
对比例3
参照实施例1的制备方法，其区别在于：将混合物Y放置于氧气气氛炉中煅烧，升温至780℃持续保温18h，升温速率为3℃/min，进气速率为4m3/h；终制备获得了富镍层状氧化物材料，化学式近似为LiNi0.874Sr0.0045Co0.058Al0.015Mn0.0388Zr0.0078W0.0019O2。
对本对比例制备的富镍层状氧化物材料进行表征，结果为：形貌为球形二次颗粒，中粒径D50为12.5μm，比表面积为0.42m2/g，Zr、W元素主要在球形二次颗粒表面呈岛状偏析，在一次颗粒中仅检测出少量Zr、W元素。
性能效果评价
对实施例1～7和对比例1～3所制备的氧化物材料进行晶格微观应变情况和电化学性能的评价，具体如下：
(1)晶格微观应变情况：
将实施例1、对比例1、对比例2、对比例3制备的氧化物材料进行LeBail结构精修后得到的Williamson-Hall图谱，结果如图4所示，图4是本申请提供的实施例1与对比例1～3所制备的氧化物材料的Williamson-Hall图。由于晶体尺寸细化和晶格微观应变(ε)都能使粉末XRD图谱的衍射峰变宽，然而晶粒尺寸和微应变的影响可以用Williamson-Hall方程分离，该方程可简述为：D·cosθ＝a+b·sinθ。其中，a，b常数项，D为粉末XRD图谱衍射峰的半峰宽(FWHM)，θ为衍射角的1/2。根据Scherrer公式可知晶粒尺寸引起的衍射峰宽化与1/cosθ成正比，而结构微应变引起的宽化Γ＝4·ε·tanθ，即与tanθ成正比。由上述可知，Williamson-Hall图谱斜率与样品中晶格微观应变成正比，截距与晶粒尺寸相关。因此可以看出，实施例1相较于对比例1、对比例2以及对比例3得到的氧化物材料的Williamson-Hall图斜率更低，即实施例1氧化物材料具有更低的晶格微观应变。
同时，通过晶格间距偏差计算得到晶格微观应变量ε的值，其中ε＝Δd/d。实施例1～7和对比例1～3所制备的氧化物材料的晶格微观应变量的具体计算结果如表1所示：
表1

通过表1可以看出，相较于对比例1～3，实施例1～7得到的富镍层状氧化物材料具有更低的晶格微观应变量，晶格微观应变量均低于0.25％，表明材料的结构稳定性得到明显改善。
(2)电化学性能：
在扣式锂二次电池中测试实施例1～7和对比例1～3所制备的氧化物材料作为锂二次电池正极材料时的电化学性能，锂二次电池及其正极极片的具体制作方式为：将所制备的正极材料粉末与乙炔黑、聚偏氟乙烯按照90:5:5的质量比混合，加入适量的N-甲基吡咯烷酮作为分散剂，研磨成浆料；随后将浆料均匀涂覆在铝箔上，120℃真空干燥10h，用对辊机将干燥好的极片进行辊压，使用切片机对铝箔进行裁剪，裁成直径为1.3cm的圆形极片，活性材料的负载量控制在12±0.2mg/cm2左右；在氩气气氛手套箱中组装半电池，水分压≤0.1ppm，氧分压≤0.1ppm；以金属锂为对电极，以1M LiPF6(EC/DMC，体积比为1:1:1)溶液为电解液，组装规格为CR2032型扣式电池，使用恒流充放电模式在室温条件下进行充放电，电压范围为2.5～4.3V，电流密度为60mA/g(0.3C倍率)进行充放电循环100圈。
为分析所制材料的热稳定性，将所制材料组装电池充电至4.3V后，在充满氩气的手套箱内拆开取出正极极片，并用DMC溶液冲洗数次，真空干燥后从极片上回收活性物，放置于差示扫描量热仪的样品坩埚中，然后采用N2气氛并控制温升速率为5℃/min进行DSC热分析，对比材料放热量与放热峰位置。
实施例1与对比例1～3所制备的氧化物材料在锂二次电池测试中的循环性能测试结果如图5所示，图5为本申请提供的实施例1与对比例1～3所制备的氧化物材料在锂二次电池测试中的循环性能对比图；实施例1～7与对比例1～3所制备的氧化物材料在锂二次电池测试中的首周充电比容量、首周放电比容量、首周库伦效率，100周后容量保持率以及DSC测试数据如表2所示：
表2

通过表2可以看出，相较于对比例1～3，实施例1～7得到的富镍层状氧化物材料在锂二次电池测试中具有更好的循环性能、更高的放热峰温度和更低的放热量，表明材料的安全性得到明显改善。
以上所述仅是本申请的优选实施方式，应当指出，对于本技术领域的普通技术人员来说，在不脱离本申请原理的前提下，还可以做出若干改进和润饰，这些改进和润饰也应视为本申请的保护范围。

Claims (16)

  1. 一种富镍层状氧化物材料，其特征在于，所述富镍层状氧化物材料的晶体结构为六方相R-3m空间群，晶格微观应变量≤0.25％。
  2. 根据权利要求1所述的富镍层状氧化物材料，其特征在于，所述富镍层状氧化物材料的通式为：LiNixAaBbCcDdO2，其中，Ni为+3价，A为+2价金属阳离子，B为+3价金属阳离子，C为+4价金属阳离子，D为+5价及以上金属阳离子，0.8≤x＜1，a>0，b>0，c>0，d≥0，且x+a+b+c+d＝1；
    优选地，所述富镍层状氧化物材料为颗粒形式，
    优选地，所述B、C和D所包含的所有种类金属阳离子中，至少有两种金属阳离子在所述富镍层状氧化物材料的一次颗粒的表面处的浓度大于所述一次颗粒的中心处。
  3. 根据权利要求2所述的富镍层状氧化物材料，其特征在于，所述A为Mg2+、Ni2+和Sr2+中的一种或多种；所述B为Al3+、Co3+、Ga3+、Y3+、La3+和Yb3+中的一种或多种；所述C为Mn4+、Zr4+、Ti4+、Sn4+和Ce4+中的一种或多种；所述D为V5+、Nb5+、Sb5+、Ta5+、Mo6+和W6+中的一种或多种。
  4. 根据权利要求1～3任一项所述的富镍层状氧化物材料，其特征在于，所述富镍层状氧化物材料满足以下条件中的至少一个条件：
    所述富镍层状氧化物材料的D50粒径为2～20μm；
    所述富镍层状氧化物材料的比表面积为0.2～2m2/g；
    所述富镍层状氧化物材料的形貌为一次颗粒或球形二次颗粒。
  5. 一种富镍层状氧化物材料的制备方法，其特征在于，包括以下步骤：
    a)将溶液I、溶液II、氢氧化钠和络合剂混合并进行络合与沉淀反应，在反应过程中控制所述氢氧化钠和络合剂的用量使混合体系的pH值维持在10～13，得到氢氧化物沉淀；
    步骤a)中，所述溶液I包括镍源化合物和水；所述溶液II包括第一金属源化合物和水；所述第一金属源化合物为C源化合物和D源化合物中的至少一种，或者为C源化合物和D源化合物中至少一种与A源化合物和B源化合物中至少一种的混合物；所述A源化合物为+2价金属阳离子所对应的水溶性金属盐，所述B源化合物为+3价金属阳离子所对应的水溶性金属盐，所述C源化合物为+4价金属阳离子所对应的水溶性金属盐，所述D源化合为+5价及以上金属阳离子所对应的水溶性金属盐；
    b)将所述氢氧化物沉淀、锂源化合物和第二金属源化合物混合，得到混合料；
    步骤b)中，所述第二金属源化合物为A源化合物、B源化合物、C源化合物和D源化合物中的一种或多种；
    c)将所述混合料在含氧气氛中进行分步焙烧，得到富镍层状氧化物材料；所述富镍层状氧化物材料的晶体结构为六方相R-3m空间群，晶格微观应变量≤0.25％。
  6. 根据权利要求5所述的制备方法，其特征在于，步骤a)中，所述溶液I中金属离子的浓度为1～5mol/L；所述溶液II中金属离子的总浓度为0.5～5mol/L。
  7. 根据权利要求5或6所述的制备方法，其特征在于，步骤a)中，所述氢氧化钠满足以下条件的至少之一：
    所述氢氧化钠以氢氧化钠水溶液的形式参与混合，
    所述氢氧化钠水溶液的浓度为0.5～4mol/L。
  8. 根据权利要求5～7任一项所述的制备方法，其特征在于，步骤a)中，所述络合剂满足以下条件的至少之一：
    所述络合剂为氨水、乙二胺四乙酸和乙二胺中的一种或多种；
    所述络合剂以络合剂水溶液的形式参与混合。
  9. 根据权利要求8所述的制备方法，其特征在于，步骤a)中，所述络合剂水溶液的浓度为0.5～10mol/L。
  10. 根据权利要求5～9任一项所述的制备方法，其特征在于，步骤a)中，所述络合与沉淀反应满足以下条件的至少之一：
    所述络合与沉淀反应在搅拌条件下进行，搅拌速率为200～1000r/min；
    所述络合与沉淀反应的温度为30～70℃；
    所述络合与沉淀反应的时间为10～50h。
  11. 根据权利要求5～10任一项所述的制备方法，其特征在于，步骤c)中，所述分步焙烧的具体过程包括：
    i)从环境温度升温至第一焙烧温度，进行一次保温焙烧；
    所述第一焙烧温度为300～600℃；升温至所述第一焙烧温度的升温速率为1～6℃/min；所述一次保温焙烧的时间为4～10h；
    ii)继续升温至第二焙烧温度，进行二次保温焙烧；
    所述第二焙烧温度为700～1000℃；升温至所述第二焙烧温度的升温速率为1～6℃/min；所述二次保温焙烧的时间为1～5h；
    iii)调温至第三焙烧温度，进行三次保温焙烧；
    所述第三焙烧温度为700～900℃，且≤第二焙烧温度；调温至所述第三焙烧温度的速率 为0～10℃/min；所述三次保温焙烧的时间为10～20h。
  12. 根据权利要求11所述的制备方法，其特征在于，所述分步焙烧的过程中持续向所用焙烧设备中通入氧气以提供焙烧所需的含氧气氛；步骤i)的氧气进气速率为0.5～5m3/h，步骤ii)的氧气进气速率为0.5～5m3/h，步骤iii)的氧气进气速率为0.5～5m3/h。
  13. 根据权利要求5所述的制备方法，其特征在于，所述第一金属源化合物包括A源化合物、B源化合物、C源化合物和任选地D源化合物。
  14. 根据权利要求5所述的制备方法，其特征在于，所述第二金属源化合物中的A源化合物、B源化合物、C源化合物或D源化合物为+2价金属阳离子、+3价金属阳离子、+4价金属阳离子或+5价金属阳离子的碳酸盐、氢氧化物或氧化物。
  15. 一种锂离子二次电池，其特征在于，所述锂离子二次电池的正极材料包括权利要求1～4任一项所述的富镍层状氧化物材料或权利要求5～14任一项所述制备方法制得的富镍层状氧化物材料。
  16. 一种用电装置，其特征在于，所述用电装置安装有权利要求15所述的锂离子二次电池。
PCT/CN2023/115761 2022-12-20 2023-08-30 富镍层状氧化物材料及其制备方法和应用 WO2024131123A1 (zh)

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