WO2023226209A1 - 一种超高镍三元正极材料及其制备方法和应用 - Google Patents

一种超高镍三元正极材料及其制备方法和应用 Download PDF

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WO2023226209A1
WO2023226209A1 PCT/CN2022/113252 CN2022113252W WO2023226209A1 WO 2023226209 A1 WO2023226209 A1 WO 2023226209A1 CN 2022113252 W CN2022113252 W CN 2022113252W WO 2023226209 A1 WO2023226209 A1 WO 2023226209A1
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ultra
high nickel
nickel ternary
preparation
lithium
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PCT/CN2022/113252
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English (en)
French (fr)
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许开华
桑雨辰
施杨
周晓燕
陈玉君
张明龙
张文艳
张翔
谢军
李伟
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格林美（无锡）能源材料有限公司
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • 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

Definitions

  • This application belongs to the technical field of lithium-ion batteries and relates to an ultra-high nickel ternary cathode material and its preparation method and application.
  • lithium-ion batteries are widely used in electric vehicles, portable electronic equipment and energy storage power stations. and other fields.
  • people have put forward higher requirements for the cruising range of electric vehicles and the energy density of lithium-ion batteries.
  • the cathode materials for automotive lithium-ion batteries are developing in the direction of high nickel. Cathode materials are gradually becoming popular because of their high energy density and low cost.
  • the extremely high nickel content not only increases the capacity of the cathode material, but also makes the material extremely sensitive to moisture and carbon dioxide.
  • the content of LiOH and Li 2 CO 3 on the surface of the material is too high, which leads to poor structural stability, cycle performance, and safety performance of the cathode material, thereby affecting the overall performance of the battery core.
  • the residual alkali content is too high, which can easily cause side reactions with the electrolyte, increase gas production, and reduce the safety performance of the battery core.
  • the generation and expansion of microcracks during the battery core cycle concentrates the isotropic stress at the grain boundaries, resulting in intergranular Cracking and particle fragmentation destroy the morphology and structure of the material.
  • the penetration of electrolyte increases side reactions, increases impedance, affects the transmission of lithium ions, and reduces structural stability and cycle performance.
  • CN113839015A discloses an ultra-high nickel single crystal cathode material and a preparation method thereof. It uses the ultra-high nickel cathode material precursor (nickel, cobalt, manganese and aluminum hydroxide) as the base raw material. By using the force of high speed and high pressure, the precursor is fully broken, and during this period, lithium source and carbonic acid are added. Strontium can promote the mutual dissolution of the lithium source and the precursor and the crystallization and co-growth at a lower temperature, reduce the mixing of lithium and nickel, and finally obtain a quasi-single crystal material through calcination.
  • the ultra-high nickel cathode material precursor nickel, cobalt, manganese and aluminum hydroxide
  • CN112310389A discloses a method for preparing an ultra-high nickel single crystal cathode material, which includes the following steps: S1. Mix the ternary precursor and lithium hydroxide at a lithium to metal molar ratio of 1.01-1.10:1, and add doping Agent, calcined in an oxygen atmosphere to obtain primary calcined material; S2. Pass the primary calcined material through coarse crushing, fine crushing, sieving, and demagnetization to obtain pulverized material; S3. Combine the pulverized material with water at a water-to-material ratio of 0.5:1 -5:1 is added to the reaction kettle, the temperature of the reaction kettle is controlled, and then the reagent is added for reaction.
  • the ultra-high nickel cathode material described in the above scheme has the problems of poor cycle performance and high residual alkali content on the surface. Therefore, an ultra-high nickel cathode material with both low residual alkali and high cycle stability is developed to improve the material's electrical performance. The chemical properties are very necessary to meet the application of power batteries in electric vehicles.
  • the purpose of this application is to provide an ultra-high nickel ternary cathode material and its preparation method and application.
  • the structural stability of the ultra-high nickel material is improved, and the cycle performance of the material is improved;
  • the organic acid is coated / Organic acid salt, the glycine source is used to react with the lithium source and other residual alkali on the surface of the ultra-high nickel cathode material to remove it, avoiding problems such as irreversible capacity loss and battery flatulence.
  • free lithium is formed on the surface of the material by combining with other coating elements.
  • the new lithium salt compound coating can effectively prevent the electrolyte from corroding the interior of the particles, reduce impedance, and improve the cycle stability of the material.
  • this application provides a method for preparing an ultra-high nickel ternary cathode material.
  • the preparation method includes the following steps:
  • the additive in step (1) includes any three or a combination of at least four of aluminum oxide, magnesium hydroxide, zirconium oxide, yttrium oxide or tungsten oxide.
  • This application prepares ultra-high nickel ternary cathode materials through a solid-phase sintering method, adds additives of at least three metal ions, makes full use of the various characteristics of the metal ions in the additives, matches various metal ions, and improves the cycle performance of the material. and thermal stability, comprehensively improving the electrochemical performance of ultra-high nickel cathode materials.
  • the primary sintering material and the glycine source are mixed in a solid phase and then heat treated.
  • the glycine molecule has both acidic and alkaline functional groups, is ionizable in water, and has strong hydrophilicity, but it is a non-polar amino acid and is soluble in extremely It is difficult to dissolve in non-polar solvents and has a high boiling point and melting point.
  • This application utilizes the acidic functional group of glycine to undergo an acid-base neutralization reaction with the lithium source on the surface of the primary sintering product, thereby reducing the residual alkali content on the surface of the positive electrode material.
  • Glycine is directly mixed with the primary sintering material instead of being used as an additive for water or alcohol washing.
  • the pickling treatment of the material avoids the direct erosion of the surface of the cathode material by water washing or alcohol washing and promotes the dissolution of lithium and other metals, resulting in the loss of capacity. It also avoids the damage to the surface structure of the material by water washing or alcohol washing.
  • aluminum glycinate, aluminum zirconium glycinate The addition of glycinate salt also has a positive effect on the surface coating of the cathode material to form a protective coating.
  • the molten organic acid salt can react with and remove the residual alkali (OH - , CO 3 2- ) on the surface of the sintered product, making the surface Free lithium combines with other coated elements (Al or Zr, etc.) to form a lithium salt compound, forming a protective coating on the surface of the cathode material, which greatly reduces the residual alkali on the surface of the material and can effectively isolate the electrolyte from corroding the interior of the material. It inhibits the occurrence of side reactions, stabilizes the structure, improves thermal stability, reduces impedance, and improves material circulation.
  • the chemical formula of the ultra-high nickel ternary precursor in step (1) is Nix Co y Mn z (OH) 2 .
  • x+y+z 1, 0.95 ⁇ x ⁇ 1, for example: 0.95, 0.96, 0.97, 0.98 or 0.99, etc., 0.01 ⁇ y ⁇ 0.1, for example: 0.01, 0.02, 0.05, 0.08 or 0.1, etc., 0.01 ⁇ z ⁇ 0.1, for example: 0.01, 0.02, 0.05, 0.08 or 0.1, etc.
  • the lithium source includes lithium hydroxide and/or lithium carbonate.
  • the ratio of the molar amount of lithium element in the lithium source to the total molar amount of metal elements in the ultra-high nickel ternary precursor is (1.01 ⁇ 1.1):1, for example: 1.01:1, 1.02:1 , 1.05:1, 1.08:1 or 1.1:1, etc.
  • the additives in step (1) include aluminum oxide, magnesium hydroxide, zirconium oxide, yttrium oxide and tungsten oxide.
  • the mass ratio of the magnesium hydroxide to the ultra-high nickel ternary precursor is (0.1-0.4):100, for example: 0.1:100, 0.2:100, 0.3:100 or 0.4:100, etc.
  • the mass ratio of the alumina to the ultra-high nickel ternary precursor is (0.1-0.4):100, for example: 0.1:100, 0.2:100, 0.3:100 or 0.4:100, etc.
  • the mass ratio of the yttrium oxide to the ultra-high nickel ternary precursor is (0.05 ⁇ 0.3):100, for example: 0.05:100, 0.08:100, 0.1:100, 0.2:100 or 0.3: 100 etc.
  • the mass ratio of the zirconium oxide to the ultra-high nickel ternary precursor is (0.05 ⁇ 0.3):100, for example: 0.05:100, 0.08:100, 0.1:100, 0.2:100 or 0.3: 100 etc.
  • the mass ratio of the tungsten oxide to the ultra-high nickel ternary precursor is (0.05 ⁇ 0.3):100, for example: 0.05:100, 0.08:100, 0.1:100, 0.2:100 or 0.3: 100 etc.
  • Mg 2+ is low-priced and has a similar ionic radius to Li+, so it can enter the lattice of the host material and occupy the Li layer, stabilizing the structure of the material.
  • Al 3+ is more easily doped. into the crystal lattice to stabilize the structure and reduce the degree of cation mixing.
  • Mg and Al reduces the initial capacity of the material
  • an appropriate amount of Mg and Al doping can significantly improve the cycle performance and thermal stability of the material; while the addition of Zr can To make up for the problem of initial capacity reduction caused by Mg and Al doping, a small amount of Zr 4+ entering the crystal lattice can stabilize the lithium ion diffusion channel, and more Zr 4+ is concentrated on the surface of the material to form a fast ion conductor, optimize grain boundaries, and improve lithium ion conductivity.
  • the rate improves the DCR of the material; due to the increase in ionic radius, the incorporation of Y 3+ into the crystal lattice will cause an increase in the unit cell parameters of the material and an increase in the unit cell volume, thereby increasing the volume of the lithium ion transmission pathway, further improving
  • the diffusion rate of lithium ions inhibits phase transition under high voltage, improves the thermal stability of the material, and can also improve the rate performance of the material and has good electrochemical reversibility; the W element can refine the grains and improve the shape of the material. appearance and improve the recycling performance of materials.
  • the temperature of the sintering treatment in step (1) is 600-900°C, for example: 600°C, 650°C, 700°C, 800°C or 900°C, etc., preferably 650-750°C.
  • the sintering treatment time is 8 to 24 hours, such as 8 hours, 10 hours, 12 hours, 16 hours, 20 hours or 24 hours, preferably 10 hours to 20 hours.
  • the glycine source in step (2) includes glycine and/or glycinate.
  • the glycinate salt includes any one or a combination of at least two of aluminum glycinate, magnesium glycinate or aluminum zirconium glycinate.
  • the mass ratio of the glycine source and the primary sintering material in step (2) is (0.1 ⁇ 5):100, for example: 0.1:100, 0.5:100, 1:100, 2:100, 3:100, 4:100 or 5:100, etc., preferably (0.1 ⁇ 3):100.
  • the temperature of the heat treatment in step (2) is 250-600°C, for example: 250°C, 300°C, 350°C, 400°C, 500°C or 600°C, etc., preferably 300-600°C.
  • the heat treatment time is 6 to 24 hours, such as 6 hours, 10 hours, 12 hours, 16 hours, 20 hours or 24 hours, preferably 6 hours to 15 hours.
  • the present application provides an ultra-high nickel ternary cathode material.
  • the ultra-high nickel ternary cathode material is prepared by the method described in the first aspect.
  • the ultra-high nickel ternary cathode material includes an inner core and a A coating layer is provided on the surface of the core.
  • the chemical formula of the core is Li 1+y ( Nia Co b Mn 1-abc B c ) 1-y O 2 , where 0 ⁇ y ⁇ 0.1, for example: 0 , 0.01, 0.02, 0.05, 0.08 or 0.1, etc., 0.95 ⁇ a ⁇ 1, such as: 0.95, 0.96, 0.97, 0.98 or 0.99, etc., 0.01 ⁇ b ⁇ 0.1, such as: 0.01, 0.02, 0.05, 0.08 or 0.1, etc., 0 ⁇ c ⁇ 0.05, for example: 0.01, 0.02, 0.03, 0.04 or 0.05, etc.
  • B is a combination of at least three of Mg 2+ , Al 3+ , Zr 4+ , Y 3+ or W 6+ .
  • the present application provides a positive electrode piece, which contains the ultra-high nickel ternary positive electrode material as described in the second aspect.
  • the present application provides a lithium-ion battery, which includes the positive electrode sheet as described in the third aspect.
  • This application prepares ultra-high nickel ternary cathode materials through a solid-phase sintering method, adds additives of at least three metal ions, makes full use of the various characteristics of the metal ions in the additives, matches various metal ions, and improves the quality of the material.
  • the cycle performance and thermal stability of the ultra-high nickel cathode material are comprehensively improved, and the acidic functional group of glycine is used to cause an acid-base neutralization reaction with the lithium source on the surface of the primary sintering product, thereby reducing the residual alkali content on the surface of the cathode material.
  • Glycine is directly mixed with the primary sintering material, which avoids direct erosion of the surface of the cathode material by water washing or alcohol washing and promotes the dissolution of lithium and other metals, resulting in loss of capacity. It also avoids damage to the surface structure of the material by water washing or alcohol washing.
  • aluminum glycinate, glycine The addition of glycinates such as aluminum and zirconium also has a positive effect on the surface coating of the cathode material to form a protective coating.
  • the molten organic acid salt can react with and remove the residual alkali (OH - , CO 3 2- ) on the surface of the sintered product, making the
  • the free lithium on the surface combines with other coating elements (Al or Zr, etc.) to form a lithium salt compound, which forms a protective coating on the surface of the cathode material, greatly reducing the residual alkali on the surface of the material and effectively isolating the electrolyte from causing damage to the interior of the material. Erosion, inhibiting the occurrence of side reactions, stabilizing the structure, improving thermal stability, reducing impedance, and improving material circulation.
  • the first-week charge specific capacity of the battery made of the cathode material described in this application can reach more than 244.3mAh/g
  • the first-week discharge specific capacity can reach more than 216.3mAh/g
  • the first-week Coulombic efficiency can reach more than 88.9%.
  • the capacity retention rate after 50 cycles can reach over 88.9%
  • the 1C discharge specific capacity can reach over 200.2mAh/g.
  • Figure 1 is an SEM image of the ultra-high nickel cathode material described in Example 4.
  • Figure 2 is an SEM image of the ultra-high nickel cathode material described in Comparative Example 1.
  • This embodiment provides an ultra-high nickel ternary cathode material.
  • the preparation method of the ultra-high nickel ternary cathode material is as follows:
  • This embodiment provides an ultra-high nickel ternary cathode material.
  • the preparation method of the ultra-high nickel ternary cathode material is as follows:
  • This embodiment provides an ultra-high nickel ternary cathode material.
  • the preparation method of the ultra-high nickel ternary cathode material is as follows:
  • This embodiment provides an ultra-high nickel ternary cathode material.
  • the preparation method of the ultra-high nickel ternary cathode material is as follows:
  • This embodiment provides an ultra-high nickel ternary cathode material.
  • the preparation method of the ultra-high nickel ternary cathode material is as follows:
  • This embodiment provides an ultra-high nickel ternary cathode material.
  • the preparation method of the ultra-high nickel ternary cathode material is as follows:
  • Example 4 The only difference between this embodiment and Example 4 is that the total mass of glycine and aluminum glycinate is 0.05% of the calcined material, and other conditions and parameters are exactly the same as in Example 4.
  • Example 4 The only difference between this embodiment and Example 4 is that the total mass of glycine and aluminum glycinate is 4% of the calcined material, and other conditions and parameters are exactly the same as in Example 4.
  • Embodiment 4 The only difference between this embodiment and Embodiment 4 is that the temperature of the heat treatment in step (2) is 650°C, and other conditions and parameters are exactly the same as those in Embodiment 4.
  • This comparative example provides an ultra-high nickel ternary cathode material.
  • the preparation method of the ultra-high nickel ternary cathode material is as follows:
  • This comparative example provides an ultra-high nickel ternary cathode material.
  • the preparation method of the ultra-high nickel ternary cathode material is as follows:
  • Example 4 The only difference between this comparative example and Example 4 is that glycine and aluminum glycinate are replaced by graphene, and other conditions and parameters are exactly the same as in Example 4.
  • the charge and discharge test parameters are set as: voltage range 2.5V-4.25V, 0.2C/0.2C ⁇ 0.5C/1C ⁇ 0.5C/1C cycle 50 times, the test results are shown in Table 1:
  • the first-week charge specific capacity of the battery made of the cathode material described in the present application can reach more than 244.3mAh/g, and the first-week discharge specific capacity can reach 216.3mAh/g. g or above, the Coulombic efficiency in the first week can reach more than 88.9%, the capacity retention rate after 50 cycles can reach more than 88.9%, and the 1C discharge specific capacity can reach more than 200.2mAh/g.
  • Mg 2+ can enter the host material lattice and occupy Li due to its low price and similar ionic radius to Li+. layer, stabilizing the structure of the material.
  • Al 3+ is more easily incorporated into the lattice to stabilize the structure and reduce the degree of cation mixing.
  • Mg and Al reduces the initial capacity of the material, appropriate amounts of Mg and Al doping can significantly improve The cycle performance and thermal stability of the material; the addition of Zr can make up for the problem of initial capacity reduction caused by Mg and Al doping.
  • a small amount of Zr 4+ entering the crystal lattice can stabilize the lithium ion diffusion channel, and more enrichment in the material
  • a fast ion conductor is formed on the surface, the grain boundaries are optimized, the lithium ion conductivity is increased, and the DCR of the material is improved; due to the increase in the ionic radius of Y 3+ , the incorporation into the crystal lattice will cause an increase in the unit cell parameters of the material and an increase in the unit cell volume, thus making
  • the volume of the lithium ion transport pathway also increases, further increasing the diffusion rate of lithium ions, suppressing phase changes under high voltage, improving the thermal stability of the material, and also improving the rate performance of the material, with good electrochemical reversibility property;
  • W element can refine the grains, improve the morphology of the material, and improve the recycling performance of the material.
  • Example 4 it can be seen from the comparison between Example 4 and Examples 7-8 that during the preparation process of the ultra-high nickel ternary cathode material described in this application, the mass ratio of the glycine source and the primary sintering material will affect the performance of the cathode material.
  • the mass ratio of the source and primary sintering material is controlled at (0.1 ⁇ 3):100, and the cathode material obtained has better performance.
  • the mass ratio of the glycine source and the primary sintering material is too small, the residual alkali in the material cannot be effectively reduced, and the residual alkali content is too high, which will easily cause side reactions with the electrolyte to increase gas production, reduce the safety performance of the battery core, and include
  • the low coating amount will not form a good protective coating on the surface of the particles, which will be easily corroded by the electrolyte and cause metal dissolution, reducing the cycle stability of the ultra-high nickel cathode material; if the mass ratio of the glycine source and the primary sintering material is too high Although it can significantly reduce the residual alkali level of the material, the coating additive amount is too high, which causes the coating layer to thicken and the transmission distance of lithium ions to become longer, resulting in an increase in impedance and further reducing the rate and cycle performance of the material.
  • Example 4 it can be seen from the comparison between Example 4 and Examples 9-10 that during the preparation process of the ultra-high nickel ternary cathode material described in this application, the temperature of the heat treatment will affect the performance of the cathode material.
  • the temperature of the heat treatment is controlled at 300 ⁇ At 600°C, the performance of the cathode material is better. If the heat treatment temperature is too low, the glycine source additive cannot be melted well, which is not conducive to the reduction of residual alkali, resulting in the formation of an uneven protective coating on the particle surface, affecting the circulation of the material.
  • Example 1 it can be seen from the comparison between Example 1 and Comparative Examples 1-2 that this application prepares ultra-high nickel ternary cathode materials through solid-phase sintering method, adds at least three kinds of metal ion additives, and makes full use of the various characteristics of the metal ions in the additives. Matching various metal ions improves the material's cycle performance and thermal stability, and comprehensively improves the electrochemical performance of ultra-high nickel cathode materials.
  • Example 1 Comparative Example 3
  • the present application uses the acidic functional group of glycine to react with the lithium source on the surface of the primary sintering product, thereby reducing the residual alkali content on the surface of the cathode material.
  • Glycine directly interacts with the primary sintering material. Mixing rather than using it as an additive for water washing or alcohol washing to pickle the material, this avoids the direct erosion of the surface of the cathode material by water washing or alcohol washing and promotes the dissolution of lithium and other metals, resulting in loss of capacity. It also avoids the impact of water washing or alcohol washing on the material. The destruction of the surface structure.
  • glycinates such as aluminum glycinate and aluminum zirconium glycinate also has a positive effect on the surface coating of the cathode material to form a protective coating.
  • the molten organic acid salt can interact with the residual alkali (OH - , CO 3 2- ) reacts and is removed, causing the free lithium on the surface to combine with other coating elements (Al or Zr, etc.) to form a lithium salt compound, forming a protective coating on the surface of the cathode material, greatly reducing the residual alkali on the surface of the material. , can effectively isolate the electrolyte from corroding the interior of the material, inhibit the occurrence of side reactions, stabilize the structure, improve thermal stability, reduce impedance, and improve material circulation.

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Abstract

本文公布了一种超高镍三元正极材料及其制备方法和应用，所述制备方法包括以下步骤：(1)将超高镍三元前驱体、锂源和添加剂混合，经烧结处理得到一次烧结料；(2)将一次烧结料和甘氨酸源混合，经热处理后得到所述超高镍三元正极材料；其中，步骤(1)所述添加剂包括氧化铝、氢氧化镁、氧化锆、氧化钇或氧化钨中的任意三种或至少四种的组合，本申请通过多元素掺杂改性提高超高镍材料的结构稳定性，改善材料的循环性能；同时包覆甘氨酸源，避免电池胀气，以及电解液对颗粒内部的侵蚀，降低阻抗，提高材料的循环稳定性。

Description

一种超高镍三元正极材料及其制备方法和应用 技术领域
本申请属于锂离子电池技术领域，涉及一种超高镍三元正极材料及其制备方法和应用。
背景技术
近年来，在碳中和、碳达峰目标的政策驱动下，新能源领域发展迅猛，锂离子电池作为一种高效的能量转换与储存装置，广泛应用于电动汽车、便携电子设备及储能电站等领域。随着电动汽车近几年井喷式地快速发展，人们对电动汽车续航里程及锂离子电池的能量密度提出了更高的要求，车用锂离子电池正极材料正往高镍化方向发展，高镍正极材料正因其具有高能量密度、低成本等特点逐渐变得热门起来。
然而随着镍含量进一步提高，尤其是超高镍正极材料(0.95≤镍含量≤1)，极高的镍含量在提高正极材料容量的同时，也使得材料对水份及二氧化碳变得极其敏感，材料表面的LiOH和Li 2CO 3含量过高，导致正极材料结构稳定性、循环性能、安全性能变差，进而影响电芯的整体性能。其中残碱含量过高，易与电解液发生副反应产气增加，降低电芯的安全性能；同时电芯循环过程中微裂纹的产生与扩展，使各向应力集中晶界处，导致晶间开裂及颗粒破碎，破坏材料的形貌与结构，同时电解液渗入使副反应增加，阻抗升高，影响锂离子的传输，结构稳定性和循环性能下降。
CN113839015A公开了一种超高镍类单晶正极材料及其制备方法。其以超高镍正极材料前驱体(镍钴锰铝氢氧化物)为基体原料，通过利用在高转速和高压力的作用力，将前驱体充分打碎，并在此期间加入锂源和碳酸锶，可以在较低温 度下促进锂源与前驱体互溶后结晶共生长，减少锂镍混排，最后通过煅烧得到类单晶材料。
CN112310389A公开了一种超高镍单晶正极材料的制备方法，包括下列步骤：S1.将三元前驱体与氢氧化锂以锂与金属摩尔比为1.01-1.10:1进行混合，并加入掺杂剂，在氧气气氛下煅烧，得一次煅烧料；S2.将一次煅烧料通过粗破碎、精破碎、过筛、除磁得粉碎料；S3.将粉碎料与水以水料比为0.5:1-5:1加入反应釜中，控制反应釜温度，再加入试剂反应，待反应完毕后进行干燥，得混料；S4.将混料与改性包覆剂混合后置于气氛炉中进行二次煅烧，再经粗破碎、精破碎、过筛、除磁，即得三元正极材料。
上述方案所述超高镍正极材料存在有循环性能差、表面残碱量高的问题，因此，开发一种兼具低残碱和高循环稳定性的超高镍正极材料，以提升材料的电化学性能，满足动力电池在电动汽车上的应用是十分必要的。
发明内容
以下是对本文详细描述的主题的概述。本概述并非是为了限制权利要求的保护范围。
本申请的目的在于提供一种超高镍三元正极材料及其制备方法和应用，通过多元素掺杂改性提高超高镍材料的结构稳定性，改善材料的循环性能；同时包覆有机酸/有机酸盐，利用甘氨酸源与超高镍正极材料表面的锂源等残碱发生反应去除，避免不可逆容量损失及电池胀气等问题，同时游离锂通过与包覆的其他元素结合在材料表面形成新的锂盐化合物涂层，可有效避免电解液对颗粒内部的侵蚀，降低阻抗，提高材料的循环稳定性。
为达此目的，本申请采用以下技术方案：
第一方面，本申请提供了一种超高镍三元正极材料的制备方法，所述制备 方法包括以下步骤：
(1)将超高镍三元前驱体、锂源和添加剂混合，经烧结处理得到一次烧结料；
(2)将一次烧结料和甘氨酸源混合，经热处理后得到所述超高镍三元正极材料；
其中，步骤(1)所述添加剂包括氧化铝、氢氧化镁、氧化锆、氧化钇或氧化钨中的任意三种或至少四种的组合。
本申请通过固相烧结法制备超高镍三元正极材料，加入至少三种金属离子的添加剂，充分利用添加剂中金属离子的各种特性，将各种金属离子进行匹配，提高了材料的循环性能和热稳定性，综合改善了超高镍正极材料的电化学性能。
本申请将一次烧结料和甘氨酸源进行固相混合后热处理，甘氨酸分子中同时具有酸性和碱性官能团，在水中可电离，具有很强的亲水性，但属于非极性氨基酸，溶于极性溶剂，而难溶于非极性溶剂，而且具有较高的沸点和熔点。本申请利用甘氨酸的酸性官能团与一次烧结产物表面的锂源发生酸碱中和反应，从而降低正极材料表面的残碱含量，甘氨酸直接与一次烧结料混合而非作为水洗或醇洗的一种添加剂对材料酸洗处理，这避免了水洗或醇洗直接对正极材料表面侵蚀促使锂等金属的溶出导致容量的损失，同时避免水洗或醇洗对材料表面结构的破坏，另外甘氨酸铝、甘氨酸铝锆等甘氨酸盐的加入也具有积极的作用对正极材料表面包覆形成保护涂层，熔融的有机酸盐可与烧结产物表面的残碱(OH -、CO 3 2-)发生反应去除，使表面的游离锂与包覆的其他元素(Al或Zr等)结合形成锂盐化合物，在正极材料表面形成保护涂层，大大降低材料表面的残碱的同时，可有效隔绝电解液对材料内部的侵蚀，抑制副反应的发生，具有稳定结构，提升热稳定性，降低阻抗，改善材料循环的功能。
可选地，步骤(1)所述超高镍三元前驱体的化学式为Ni xCo yMn z(OH) 2。其中，x+y+z＝1，0.95≤x＜1，例如：0.95、0.96、0.97、0.98或0.99等，0.01≤y≤0.1，例如：0.01、0.02、0.05、0.08或0.1等，0.01≤z≤0.1，例如：0.01、0.02、0.05、0.08或0.1等。
可选地，所述锂源包括氢氧化锂和/或碳酸锂。
可选地，所述锂源中的锂元素的摩尔量和超高镍三元前驱体中的金属元素总摩尔量之比为(1.01～1.1):1，例如：1.01:1、1.02:1、1.05:1、1.08:1或1.1:1等。
可选地，步骤(1)所述添加剂包括氧化铝、氢氧化镁、氧化锆、氧化钇和氧化钨。
可选地，所述氢氧化镁与所述超高镍三元前驱体的质量比为(0.1～0.4):100，例如：0.1:100、0.2:100、0.3:100或0.4:100等。
可选地，所述氧化铝与所述超高镍三元前驱体的质量比为(0.1～0.4):100，例如：0.1:100、0.2:100、0.3:100或0.4:100等。
可选地，所述氧化钇与所述超高镍三元前驱体的质量比为(0.05～0.3):100，例如：0.05:100、0.08:100、0.1:100、0.2:100或0.3:100等。
可选地，所述氧化锆与所述超高镍三元前驱体的质量比为(0.05～0.3):100，例如：0.05:100、0.08:100、0.1:100、0.2:100或0.3:100等。
可选地，所述氧化钨与所述超高镍三元前驱体的质量比为(0.05～0.3):100，例如：0.05:100、0.08:100、0.1:100、0.2:100或0.3:100等。
本申请所述超高镍三元正极材料中，Mg 2+由于低价并且与Li+具有相近的离子半径从而可以进入主体材料晶格占据Li层，稳定材料的结构，同样Al 3+更容易掺入晶格稳定结构，降低阳离子混排程度，尽管Mg、Al的加入降低了材料的初始容量，但适量的Mg、Al掺杂能够显著提高材料的循环性能和热稳定性；而 Zr的加入能够弥补Mg、Al掺杂造成的初始容量降低的问题，少量的Zr 4+进入晶格能够稳定锂离子扩散通道，更多的富集在材料表面形成快离子导体，优化晶界，提高锂离子电导率改善材料的DCR；Y 3+由于离子半径加大，掺入晶格会引起材料晶胞参数的增加，晶胞体积增大，从而使锂离子传输途径的体积也随之增大，进一步提高锂离子的扩散速率，抑制高电压下的相变，提高材料的热稳定性，同时也能够提高材料的倍率性能，具有良好的电化学可逆性；W元素能够细化晶粒，改善材料的形貌，提升材料的循环性能。
可选地，步骤(1)所述烧结处理的温度为600～900℃，例如：600℃、650℃、700℃、800℃或900℃等，优选为650～750℃。
可选地，所述烧结处理的时间为8～24h，例如：8h、10h、12h、16h、20h或24h等，优选为10～20h。
可选地，步骤(2)所述甘氨酸源包括甘氨酸和/或甘氨酸盐。
可选地，所述甘氨酸盐包括甘氨酸铝、甘氨酸镁或甘氨酸铝锆中的任意一种或至少两种的组合。
可选地，步骤(2)所述甘氨酸源和一次烧结料的质量比为(0.1～5):100，例如：0.1:100、0.5:100、1:100、2:100、3:100、4:100或5:100等，优选为(0.1～3):100。
可选地，步骤(2)所述热处理的温度为250～600℃，例如：250℃、300℃、350℃、400℃、500℃或600℃等，优选为300～600℃。
可选地，所述热处理的时间为6～24h，例如：6h、10h、12h、16h、20h或24h等，优选为6～15h。
第二方面，本申请提供了一种超高镍三元正极材料，所述超高镍三元正极材料通过如第一方面所述方法制得，所述超高镍三元正极材料包括内核和设置在所述内核表面的包覆层，所述内核的化学式为Li 1+y(Ni aCo bMn 1-a-b-cB c) 1-yO 2，其 中，0≤y≤0.1，例如：0、0.01、0.02、0.05、0.08或0.1等，0.95≤a≤1，例如：0.95、0.96、0.97、0.98或0.99等，0.01≤b≤0.1，例如：0.01、0.02、0.05、0.08或0.1等，0＜c≤0.05，例如：0.01、0.02、0.03、0.04或0.05等，B为Mg 2+、Al 3+、Zr 4+、Y 3+或W 6+中的任意至少三种的组合。
第三方面，本申请提供了一种正极极片，所述正极极片包含如第二方面所述的超高镍三元正极材料。
第四方面，本申请提供了一种锂离子电池，所述锂离子电池包含如第三方面所述的正极极片。
相对于现有技术，本申请具有以下有益效果：
(1)本申请通过固相烧结法制备超高镍三元正极材料，加入至少三种金属离子的添加剂，充分利用添加剂中金属离子的各种特性，将各种金属离子进行匹配，提高了材料的循环性能和热稳定性，综合改善了超高镍正极材料的电化学性能，利用甘氨酸的酸性官能团与一次烧结产物表面的锂源发生酸碱中和反应，从而降低正极材料表面的残碱含量，甘氨酸直接与一次烧结料混合，避免了水洗或醇洗直接对正极材料表面侵蚀促使锂等金属的溶出导致容量的损失，同时避免水洗或醇洗对材料表面结构的破坏，另外甘氨酸铝、甘氨酸铝锆等甘氨酸盐的加入也具有积极的作用对正极材料表面包覆形成保护涂层，熔融的有机酸盐可与烧结产物表面的残碱(OH -、CO 3 2-)发生反应去除，使表面的游离锂与包覆的其他元素(Al或Zr等)结合形成锂盐化合物，在正极材料表面形成保护涂层，大大降低材料表面的残碱的同时，可有效隔绝电解液对材料内部的侵蚀，抑制副反应的发生，具有稳定结构，提升热稳定性，降低阻抗，改善材料循环的功能。
(2)本申请所述正极材料制成得电池的首周充电比容量可达244.3mAh/g 以上，首周放电比容量可达216.3mAh/g以上，首周库伦效率可达88.9％以上，循环50圈容量保持率可达88.9％以上，1C放电比容量可达200.2mAh/g以上。
在阅读并理解了详细描述和附图后，可以明白其他方面。
附图说明
图1是实施例4所述超高镍正极材料的SEM图。
图2是对比例1所述超高镍正极材料的SEM图。
具体实施方式
下面通过具体实施方式来进一步说明本申请的技术方案。本领域技术人员应该明了，所述实施例仅仅是帮助理解本申请，不应视为对本申请的具体限制。
实施例1
本实施例提供了一种超高镍三元正极材料，所述超高镍三元正极材料的制备方法如下：
(1)将Ni 0.96Co 0.03Mn 0.01(OH) 2与电池级单水氢氧化锂以锂与金属摩尔比1.01:1在高混机中进行混合，并加入三元前驱体质量0.1wt％的氢氧化镁、0.1wt％的氧化铝、0.05wt％的氧化锆在氧气气氛下700℃以2℃/min的升温速率保温10h，随炉自然冷却，之后经过粉碎、325目过筛、除磁，得到超高镍正极材料一次烧结料；
(2)将一次烧结料与添加量为一次烧结料质量0.3wt％的甘氨酸、0.1wt％的甘氨酸铝混合均匀，随后在氧气气氛下450℃以2℃/min的升温速率保温6h，随炉自然冷却，之后经过粉碎、325目过筛、除磁，即得到Mg、Al、Zr共掺的Li 1.01Ni 0.96Co 0.03Mn 0.01O 2超高镍正极材料。
实施例2
本实施例提供了一种超高镍三元正极材料，所述超高镍三元正极材料的制备方法如下：
(1)将Ni 0.96Co 0.03Mn 0.01(OH) 2与电池级单水氢氧化锂以锂与金属摩尔比1.01:1在高混机中进行混合，并加入三元前驱体质量0.1wt％的氢氧化镁、0.1wt％的氧化铝、0.05wt％的氧化锆、0.05wt％的氧化钇在氧气气氛下700℃以2℃/min的升温速率保温10h，随炉自然冷却，之后经过粉碎、325目过筛、除磁，得到超高镍正极材料一次烧结料；
(2)将一次烧结料与添加量为一次烧结料质量0.3wt％的甘氨酸、0.1wt％的甘氨酸铝混合均匀，随后在氧气气氛下450℃以2℃/min的升温速率保温6h，随炉自然冷却，之后经过粉碎、325目过筛、除磁，即得到Mg、Al、Zr、Y共掺的Li 1.01Ni 0.96Co 0.03Mn 0.01O 2超高镍正极材料。
实施例3
本实施例提供了一种超高镍三元正极材料，所述超高镍三元正极材料的制备方法如下：
(1)将Ni 0.96Co 0.03Mn 0.01(OH) 2与电池级单水氢氧化锂以锂与金属摩尔比1.01:1在高混机中进行混合，并加入三元前驱体质量0.1wt％的氢氧化镁、0.2wt％的氧化铝、0.1wt％的氧化锆、0.05wt％的氧化钇在氧气气氛下700℃以2℃/min的升温速率保温10h，随炉自然冷却，之后经过粉碎、325目过筛、除磁，得到超高镍正极材料一次烧结料；
(2)将一次烧结料与添加量为一次烧结料质量0.3wt％的甘氨酸、0.1wt％的甘氨酸铝锆混合均匀，随后在氧气气氛下450℃以2℃/min的升温速率保温6h，随炉自然冷却，之后经过粉碎、325目过筛、除磁，即得到Mg、Al、Zr、Y共 掺的Li 1.01Ni 0.96Co 0.03Mn 0.01O 2超高镍正极材料。
实施例4
本实施例提供了一种超高镍三元正极材料，所述超高镍三元正极材料的制备方法如下：
(1)将Ni 0.96Co 0.03Mn 0.01(OH) 2与电池级单水氢氧化锂以锂与金属摩尔比1.01:1在高混机中进行混合，并加入三元前驱体质量0.1wt％的氢氧化镁、0.2wt％的氧化铝、0.1wt％的氧化锆、0.05wt％的氧化钇、0.1wt％的氧化钨在氧气气氛下700℃以2℃/min的升温速率保温10h，随炉自然冷却，之后经过粉碎、325目过筛、除磁，得到超高镍正极材料一次烧结料；
(2)将一次烧结料与添加量为一次烧结料质量0.3wt％的甘氨酸、0.1wt％的甘氨酸铝锆混合均匀，随后在氧气气氛下450℃以2℃/min的升温速率保温6h，随炉自然冷却，之后经过粉碎、325目过筛、除磁，即得到Mg、Al、Zr、Y、W共掺的Li 1.01Ni 0.96Co 0.03Mn 0.01O 2超高镍正极材料。
所述超高镍正极材料的SEM图如图1所示。
实施例5
本实施例提供了一种超高镍三元正极材料，所述超高镍三元正极材料的制备方法如下：
(1)将Ni 0.96Co 0.03Mn 0.01(OH) 2与电池级单水氢氧化锂以锂与金属摩尔比1.01:1在高混机中进行混合，并加入三元前驱体质量0.2wt％的氢氧化镁、0.1wt％的氧化铝、0.05wt％的氧化锆、0.05wt％的氧化钇、0.1wt％的氧化钨在氧气气氛下710℃以2℃/min的升温速率保温10h，随炉自然冷却，之后经过粉碎、325目过筛、除磁，得到超高镍正极材料一次烧结料；
(2)将一次烧结料与添加量为一次烧结料质量0.3wt％的甘氨酸、0.1wt％的甘氨酸铝锆混合均匀，随后在氧气气氛下450℃以2℃/min的升温速率保温6h，随炉自然冷却，之后经过粉碎、325目过筛、除磁，即得到Mg、Al、Zr、Y、W共掺的Li 1.01Ni 0.96Co 0.03Mn 0.01O 2超高镍正极材料。
实施例6
本实施例提供了一种超高镍三元正极材料，所述超高镍三元正极材料的制备方法如下：
(1)将Ni 0.96Co 0.03Mn 0.01(OH) 2与电池级单水氢氧化锂以锂与金属摩尔比1.01:1在高混机中进行混合，并加入三元前驱体质量0.2wt％的氢氧化镁、0.2wt％的氧化铝、0.15wt％的氧化锆、0.1wt％的氧化钇、0.1wt％的氧化钨在氧气气氛下710℃以2℃/min的升温速率保温10h，随炉自然冷却，之后经过粉碎、325目过筛、除磁，得到超高镍正极材料一次烧结料；
(2)将一次烧结料与添加量为一次烧结料质量0.3wt％的甘氨酸、0.1wt％的甘氨酸铝锆混合均匀，随后在氧气气氛下450℃以2℃/min的升温速率保温6h，随炉自然冷却，之后经过粉碎、325目过筛、除磁，即得到Mg、Al、Zr、Y、W共掺的Li 1.01Ni 0.96Co 0.03Mn 0.01O 2超高镍正极材料。
实施例7
本实施例与实施例4区别仅在于，甘氨酸和甘氨酸铝的总质量为一烧材料的0.05％，其他条件与参数与实施例4完全相同。
实施例8
本实施例与实施例4区别仅在于，甘氨酸和甘氨酸铝的总质量为一烧材料的4％，其他条件与参数与实施例4完全相同。
实施例9
本实施例与实施例4区别仅在于，步骤(2)热处理的温度为250℃，其他条件与参数与实施例4完全相同。
实施例10
本实施例与实施例4区别仅在于，步骤(2)热处理的温度为650℃，其他条件与参数与实施例4完全相同。
对比例1
本对比例提供了一种超高镍三元正极材料，所述超高镍三元正极材料的制备方法如下：
(1)将Ni 0.96Co 0.03Mn 0.01(OH) 2与电池级单水氢氧化锂以锂与金属摩尔比1.01:1在高混机中进行混合，并加入三元前驱体质量0.1wt％的氢氧化镁，在氧气气氛下700℃以2℃/min的升温速率保温10h，随炉自然冷却，之后经过粉碎、325目过筛、除磁，得到超高镍正极材料一次烧结料；
(2)将一次烧结料与添加量为一次烧结料质量0.1wt％的氧化铝及0.1wt％的氧化锆混合均匀，随后在氧气气氛下450℃以2℃/min的升温速率保温6h，随炉自然冷却，之后经过粉碎、325目过筛、除磁，即得到Mg掺杂的Li 1.01Ni 0.96Co 0.03Mn 0.01O 2超高镍正极材料。
所述超高镍正极材料的SEM图如图2所示。
对比例2
本对比例提供了一种超高镍三元正极材料，所述超高镍三元正极材料的制备方法如下：
(1)将Ni 0.96Co 0.03Mn 0.01(OH) 2与电池级单水氢氧化锂以锂与金属摩尔比 1.01:1在高混机中进行混合，并加入三元前驱体质量0.1wt％的氢氧化镁、0.1wt％的氧化铝，在氧气气氛下700℃以2℃/min的升温速率保温10h，随炉自然冷却，之后经过粉碎、325目过筛、除磁，得到超高镍正极材料一次烧结料；
(2)将一次烧结料与添加量为一次烧结料质量0.3wt％的甘氨酸、0.1wt％的氧化铝及0.1wt％的氧化锆混合均匀，随后在氧气气氛下450℃以2℃/min的升温速率保温6h，随炉自然冷却，之后经过粉碎、325目过筛、除磁，即得到Mg、Al共掺的Li 1.01Ni 0.96Co 0.03Mn 0.01O 2超高镍正极材料。
对比例3
本对比例与实施例4区别仅在于，将甘氨酸和甘氨酸铝换成石墨烯，其他条件与参数与实施例4完全相同。
性能测试：
1.取实施例1-10和对比例1-3得到的正极材料，按96.9(正极材料)：1.6(粘结剂PVDF)：1.5(导电剂SP)的比例称取三种材料；
2.加入分散剂NMP在匀浆机中混合均匀制成浆料，然后使用涂布机涂布在导电铝箔平上(面密度15.0～17.0mg/cm 2)；
3.放入100℃鼓风干燥箱干燥2h，然后裁剪成直径13mm极片、称重、140℃真空烘烤3h；
4.以锂金属为负极，在氩气手套箱中组装CR2032扣式电池；
室温条件下将扣式电池放入蓝电测试系统进行充放电测试。充放电测试参数设置为：电压范围2.5V-4.25V，0.2C/0.2C→0.5C/1C→0.5C/1C循环50次，测试结果如表1所示：
表1
Figure PCTCN2022113252-appb-000001
由表1可以看出，由实施例1-10可得，本申请所述正极材料制成得电池的首周充电比容量可达244.3mAh/g以上，首周放电比容量可达216.3mAh/g以上，首周库伦效率可达88.9％以上，循环50圈容量保持率可达88.9％以上，1C放电比容量可达200.2mAh/g以上。
由实施例1和实施例2-6对比可得，本申请所述超高镍三元正极材料中， Mg 2+由于低价并且与Li+具有相近的离子半径从而可以进入主体材料晶格占据Li层，稳定材料的结构，同样Al 3+更容易掺入晶格稳定结构，降低阳离子混排程度，尽管Mg、Al的加入降低了材料的初始容量，但适量的Mg、Al掺杂能够显著提高材料的循环性能和热稳定性；而Zr的加入能够弥补Mg、Al掺杂造成的初始容量降低的问题，少量的Zr 4+进入晶格能够稳定锂离子扩散通道，更多的富集在材料表面形成快离子导体，优化晶界，提高锂离子电导率改善材料的DCR；Y 3+由于离子半径加大，掺入晶格会引起材料晶胞参数的增加，晶胞体积增大，从而使锂离子传输途径的体积也随之增大，进一步提高锂离子的扩散速率，抑制高电压下的相变，提高材料的热稳定性，同时也能够提高材料的倍率性能，具有良好的电化学可逆性；W元素能够细化晶粒，改善材料的形貌，提升材料的循环性能。
由实施例4和实施例7-8对比可得，本申请所述超高镍三元正极材料的制备过程中，甘氨酸源和一次烧结料的质量比会影响制得正极材料的性能，将甘氨酸源和一次烧结料的质量比控制在(0.1～3):100，制得正极材料性能较好。若甘氨酸源和一次烧结料的质量比过小，致使材料的残碱不能得到有效的降低，残碱含量过高，易与电解液发生副反应产气增加，降低电芯的安全性能，同时包覆量较低导致不能很好的在颗粒表面形成保护涂层，易受到电解液的侵蚀而使金属溶出，降低超高镍正极材料的循环稳定性；若甘氨酸源和一次烧结料的质量比过大，虽能明显降低材料的残碱水平，但包覆添加剂量过高导致包覆涂层增厚，锂离子的传输距离变长，致使阻抗增加，进一步降低材料的倍率与循环性能。
由实施例4和实施例9-10对比可得，本申请所述超高镍三元正极材料的制 备过程中，热处理的温度会影响制得正极材料的性能，将热处理的温度控制在300～600℃，制得正极材料性能较好，若热处理的温度过低，甘氨酸源添加剂不能很好的熔融，不利于残碱的降低，导致在颗粒表面形成不均匀的保护涂层，影响材料的循环性能，同时甘氨酸分解不充分会有碳的残留，会影响容量的发挥；若热处理的温度过高，甘氨酸源添加剂分解过快，不能很好的降低残碱，同时温度过高使材料晶粒尺寸变大，阻碍锂离子的传输，降低材料的倍率性能。
由实施例1和对比例1-2对比可得，本申请通过固相烧结法制备超高镍三元正极材料，加入至少三种金属离子的添加剂，充分利用添加剂中金属离子的各种特性，将各种金属离子进行匹配，提高了材料的循环性能和热稳定性，综合改善了超高镍正极材料的电化学性能。
由实施例1和对比例3对比可得，本申请利用甘氨酸的酸性官能团与一次烧结产物表面的锂源发生酸碱中和反应，从而降低正极材料表面的残碱含量，甘氨酸直接与一次烧结料混合而非作为水洗或醇洗的一种添加剂对材料酸洗处理，这避免了水洗或醇洗直接对正极材料表面侵蚀促使锂等金属的溶出导致容量的损失，同时避免水洗或醇洗对材料表面结构的破坏，另外甘氨酸铝、甘氨酸铝锆等甘氨酸盐的加入也具有积极的作用对正极材料表面包覆形成保护涂层，熔融的有机酸盐可与烧结产物表面的残碱(OH -、CO 3 2-)发生反应去除，使表面的游离锂与包覆的其他元素(Al或Zr等)结合形成锂盐化合物，在正极材料表面形成保护涂层，大大降低材料表面的残碱的同时，可有效隔绝电解液对材料内部的侵蚀，抑制副反应的发生，具有稳定结构，提升热稳定性，降低阻抗，改善材料循环的功能。
申请人声明，以上所述仅为本申请的具体实施方式，但本申请的保护范围 并不局限于此，所属技术领域的技术人员应该明了，任何属于本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到的变化或替换，均落在本申请的保护范围和公开范围之内。

Claims (10)

  1. 一种超高镍三元正极材料的制备方法，其中，所述制备方法包括以下步骤：
    (1)将超高镍三元前驱体、锂源和添加剂混合，经烧结处理得到一次烧结料；
    (2)将一次烧结料和甘氨酸源混合，经热处理后得到所述超高镍三元正极材料；
    其中，步骤(1)所述添加剂包括氧化铝、氢氧化镁、氧化锆、氧化钇或氧化钨中的任意三种或至少四种的组合。
  2. 如权利要求1所述的制备方法，其中，步骤(1)所述超高镍三元前驱体的化学式为Ni xCo yMn z(OH) 2；其中，x+y+z＝1，0.95≤x＜1，0.01≤y≤0.1，0.01≤z≤0.1；
    可选地，所述锂源包括氢氧化锂和/或碳酸锂；
    可选地，所述锂源中的锂元素的摩尔量和超高镍三元前驱体中的金属元素总摩尔量之比为(1.01～1.1):1。
  3. 如权利要求1或2所述的制备方法，其中，步骤(1)所述添加剂包括氧化铝、氢氧化镁、氧化锆、氧化钇和氧化钨；
    可选地，所述氢氧化镁与所述超高镍三元前驱体的质量比为(0.1～0.4):100；
    可选地，所述氧化铝与所述超高镍三元前驱体的质量比为(0.1～0.4):100；
    可选地，所述氧化钇与所述超高镍三元前驱体的质量比为(0.05～0.3):100；
    可选地，所述氧化锆与所述超高镍三元前驱体的质量比为(0.05～0.3):100；
    可选地，所述氧化钨与所述超高镍三元前驱体的质量比为(0.05～0.3):100。
  4. 如权利要求1-3任一项所述的制备方法，其中，步骤(1)所述烧结处理的温度为600～900℃，优选为650～750℃；
    可选地，所述烧结处理的时间为8～24h，优选为10～20h。
  5. 如权利要求1-4任一项所述的制备方法，其中，步骤(2)所述甘氨酸源包括甘氨酸和/或甘氨酸盐；
    可选地，所述甘氨酸盐包括甘氨酸铝、甘氨酸镁或甘氨酸铝锆中的任意一种或至少两种的组合。
  6. 如权利要求1-5任一项所述的制备方法，其中，步骤(2)所述甘氨酸源和一次烧结料的质量比为(0.1～5):100，优选为(0.1～3):100。
  7. 如权利要求1-6任一项所述的制备方法，其中，步骤(2)所述热处理的温度为250～600℃，优选为300～600℃；
    可选地，所述热处理的时间为6～24h，优选为6～15h。
  8. 一种超高镍三元正极材料，其中所述超高镍三元正极材料通过如权利要求1-7任一项所述方法制得，所述超高镍三元正极材料包括内核和设置在所述内核表面的包覆层，所述内核的化学式为Li 1+y(Ni aCo bMn 1-a-b-cB c) 1-yO 2，其中，0≤y≤0.1，0.95≤a＜1，0.01≤b≤0.1，0≤c≤0.05，B为Mg 2+、Al 3+、Zr 4+、Y 3+或W 6+中的任意至少三种的组合。
  9. 一种正极极片，其中所述正极极片包含如权利要求8所述的超高镍三元正极材料。
  10. 一种锂离子电池，其中所述锂离子电池包含如权利要求9所述的正极极片。
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