WO2024093457A1 - 正极材料、用于制备其的方法及包含其的锂离子二次电池 - Google Patents

正极材料、用于制备其的方法及包含其的锂离子二次电池 Download PDF

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WO2024093457A1
WO2024093457A1 PCT/CN2023/114270 CN2023114270W WO2024093457A1 WO 2024093457 A1 WO2024093457 A1 WO 2024093457A1 CN 2023114270 W CN2023114270 W CN 2023114270W WO 2024093457 A1 WO2024093457 A1 WO 2024093457A1
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acid
positive electrode
electrode material
organic acid
coating layer
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English (en)
French (fr)
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李于利
杨思鸣
武志一正
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株式会社村田制作所
李于利
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Publication of WO2024093457A1 publication Critical patent/WO2024093457A1/zh

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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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • 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
    • 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
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • 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
    • 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

  • the present invention relates to the field of lithium ion secondary batteries, and in particular to a positive electrode material for a lithium battery, a method for preparing the positive electrode material, and a lithium ion secondary battery comprising the positive electrode material.
  • high-nickel materials are the main direction of positive electrode material development due to their high energy density and are widely used in the field of power batteries.
  • the residual alkali (including LiOH and Li 2 CO 3 ) on the surface of high-nickel materials will increase with the increase of nickel content, resulting in poor processing performance; and the residual alkali will cause gas production in the battery.
  • the main purpose of the present invention is to provide a positive electrode material for a lithium battery, a method for preparing the same and a lithium ion secondary battery containing the same, so as to solve the problem that the method for reducing the residual alkali on the surface of high-nickel materials in the prior art leads to increased battery impedance and deterioration of cycle performance.
  • the present invention provides a new high-nickel material with very little residual alkali on the surface of the material.
  • the surface has a RCOOLi-like substance as a coating layer, which can stabilize the material structure, reduce impedance, and greatly improve the material's cycle performance.
  • the present invention provides a positive electrode material for a lithium ion battery, comprising a high-nickel material; and a coating layer on the surface of the high-nickel material, wherein the coating layer comprises a compound of formula (I) C x H yn O z Li n (I)
  • x, y, z, and n are each independently an integer of 1 ⁇ x ⁇ 10, 2 ⁇ y ⁇ 20, 2 ⁇ z ⁇ 12, and 1 ⁇ n ⁇ 3.
  • the compound of formula (I) and the compound of formula (II) are Li salts of organic acids
  • the organic acid includes maleic acid, acrylic acid, fumaric acid, malonic acid, oxalic acid, malic acid, glycolic acid, succinic acid, citric acid, triacylglycerol and aconite.
  • acids preferably one or more of maleic acid, malonic acid and oxalic acid, most preferably maleic acid.
  • the molar percentage a of the compound of formula (I) in the coating layer is 50% ⁇ a ⁇ 100%
  • the molar percentage b of the compound of formula (II) in the coating layer is 0% ⁇ b ⁇ 50%, preferably 1 ⁇ a/b ⁇ 3.
  • the coating layer uniformly covers the surface of the high-nickel material.
  • the thickness of the coating layer is 1-100 nm, and the mass fraction of the coating layer in the high-nickel material is 0.1-10 wt %, preferably 1-5 wt %.
  • the coating layer exists simultaneously on the surface of the secondary particles of the high-nickel material and on the grain boundaries of the primary particles.
  • the present invention provides a method for preparing the positive electrode material described in any one of the above aspects, comprising the following steps: mixing an organic acid with a non-aqueous solvent to obtain an organic acid solution; adding the high-nickel material to the organic acid solution and stirring to obtain a mixed solution; filtering the mixed solution to obtain a mixture; and vacuum drying, grinding, and sieving the mixture to obtain the positive electrode material; wherein the coating layer is produced by the reaction of the organic acid with LiOH and/or Li2CO3 contained in the high-nickel material.
  • the pKa of the organic acid is 1-5.
  • the organic acid includes one or more of maleic acid, acrylic acid, fumaric acid, malonic acid, oxalic acid, malic acid, glycolic acid, succinic acid, citric acid, triglyceric acid and aconitic acid.
  • the organic acid is one or more of maleic acid, malonic acid and oxalic acid, preferably maleic acid.
  • the non-aqueous solvent includes one or more of methanol, ethanol, isopropanol, ethylene glycol and glycerol.
  • the mass fraction of the organic acid in the organic acid solution is 0.1wt%-35wt%
  • the mass ratio of the high-nickel material to the organic acid solution is 1:0.2-1:5
  • the molar ratio of the total Li amount in LiOH and/or Li2CO3 contained in the high-nickel material to the organic acid in the organic acid solution is 1:0.1-1:4.
  • the stirring is performed at a speed of 50-500 rpm for 0.1-8 h
  • the vacuum drying is performed at a temperature of 60-150° C. for 0.1-12 h
  • the sieve size used for sieving is 50-500 mesh.
  • the present invention provides a lithium-ion secondary battery, including a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte, wherein the positive electrode sheet comprises a positive electrode material described in any one of the above aspects or prepared by the method described in any one of the above aspects.
  • the positive electrode material for lithium battery, the method for preparing the positive electrode material and the lithium ion secondary battery containing the positive electrode material of the present invention can reduce the residual alkali in the high-nickel positive electrode material and improve the impedance and cycle performance at the same time.
  • FIG. 1 is a schematic diagram of a reaction process of an organic acid and a residual alkali according to an embodiment of the present invention.
  • FIG. 2 is a graph showing cycle retention rates with respect to cycle numbers of batteries prepared according to examples of the present invention and comparative examples.
  • FIG. 3 is a ToF-SIMS spectrum of the positive electrode material prepared according to Example 1 of the present invention.
  • FIG. 4 is a ToF-SIMS spectrum of the positive electrode material prepared according to Comparative Example 3.
  • the prior art uses water washing modification to reduce the residual alkali on the surface of high-nickel materials, but NiO-like substances will be generated on the surface of the water-washed modified material, resulting in increased battery impedance, and lattice lithium in the material will precipitate, causing the material structure to be unstable and the cycle performance to deteriorate.
  • the present invention provides a positive electrode material for a lithium battery, wherein the high-nickel material is washed with an organic acid solution, and the organic acid reacts with the residual alkali on the surface of the material to eliminate the residual alkali, and at the same time, a substance with a RCOOLi structure is generated, which can be coated on the surface of the high-nickel material.
  • the high-nickel positive electrode material of the present invention has been washed with an organic acid, and only a trace amount of alkaline substances remain on the surface, and at the same time, it has good stability.
  • the RCOOLi substance generated by the reaction of the organic acid and the alkali can reduce impedance, and the cycle performance is also greatly improved.
  • a positive electrode material for a lithium ion battery comprising a high-nickel material; and a coating layer on the surface of the high-nickel material, wherein the coating layer of the R-Li structure comprises a compound of formula (I) C x H yn O z Li n (I)
  • x, y, z, and n are each independently an integer of 1 ⁇ x ⁇ 10, 2 ⁇ y ⁇ 20, 2 ⁇ z ⁇ 12, and 1 ⁇ n ⁇ 3.
  • the ratio of lithium to metal is slightly increased (i.e., lithium salt is appropriately excessive) to compensate for the loss caused during the sintering process. Therefore, there is excess Li in the prepared high-nickel material, mainly in the form of Li 2 O, which easily reacts with CO 2 and H 2 O in the air to generate Li 2 CO 3 and LiOH.
  • the higher the nickel content in the high-nickel material the more LiNiO 2 there is in the material, and LiNiO 2 can also react with H 2 O to generate LiOH, generating more LiOH.
  • the inventors unexpectedly found that by using a specific organic acid to wash the high-nickel material, the residual alkali on the surface of the high-nickel material can be removed, and the compound generated by the reaction of the organic acid and the residual alkali can form a coating layer of RCOOLi substance on the surface of the high-nickel material.
  • the above-mentioned coating layer according to the present invention can reduce impedance and improve cycle performance.
  • RCOOLi substance is a mixture of the product of complete reaction of organic acid and base (i.e., compound of formula (II)) and the product of incomplete reaction (i.e., compound of formula (I)).
  • the reaction will consume lithium in the lattice of the positive electrode material, reducing the active lithium of the material itself, thereby reducing the capacity.
  • all RCOOLi substances are products of incomplete reaction, their ion conductivity will be lacking and the impedance performance will be affected.
  • the compound of formula (I) and the compound of formula (II) are Li salts of organic acids
  • the coating layer of the present invention is the product of the reaction of an organic acid and residual lithium (including Li2CO3 and LiOH ), i.e., a Li salt of an organic acid, wherein the organic acid has the general formula CxHyOz .
  • the organic acid comprises one or more of maleic acid, acrylic acid, fumaric acid, malonic acid, oxalic acid, malic acid, glycolic acid, succinic acid, citric acid, trisaccharic acid and aconitic acid, preferably one or more of maleic acid, malonic acid and oxalic acid, most preferably maleic acid.
  • the molar percentage a of the compound of formula (I) in the coating layer is 50% ⁇ a ⁇ 100%, and the molar percentage b of the compound of formula (II) in the coating layer is 0% ⁇ b ⁇ 50%, preferably 1 ⁇ a/b ⁇ 3.
  • the reaction of the organic acid and the base produces a completely reacted product (i.e., a compound of formula (II)) and an incompletely reacted product (i.e., a compound of formula (I)).
  • a suitable ratio between the two helps to achieve the best coating effect. If the above ratio a/b is less than 1, it means that the complete reaction product is mostly, which will consume additional lithium in the positive electrode material lattice, resulting in a decrease in material capacity. If the ratio a/b is greater than 3, it means that the incomplete reaction product is mostly, which will cause the ionic conductivity of the coating layer to decrease, affecting the impedance.
  • the coating layer shows a characteristic peak in the range of 1600-1800 cm -1 in FTIR , a characteristic peak in the range of 288-290 eV in XPS C1s, and fragment peaks of CxHyn-1OzLin- and Cx - 1Hyn - 1Oz -2Lin- in ToF-SIMS test.
  • the fragment peaks are shown as uniformly covering the surface of the high nickel material in the two-dimensional imaging map (also known as element distribution map, mapping map) of the ToF-SIMS test.
  • the characteristic peak in the range of 1600-1800 cm -1 in FTIR represents C O
  • the peak in XPS at 285-287eV represents C O
  • the coating layer has a thickness of 1-100 nm, and a mass fraction of 0.1-10 wt %, preferably 1-5 wt % in the high nickel material.
  • the coating layer exists on the surface of the secondary particles of the high nickel material and on the grain boundaries of the primary particles.
  • the inventors have found through testing that when the mass fraction of the coating layer in the high-nickel material is 1-10wt%, it is most beneficial to the material performance.
  • the inventors also found through electron microscope observation that the thickness of the coating layer prepared according to the embodiment of the present invention is 1-100nm.
  • the high-nickel material particles are large particles formed by the agglomeration of multiple small particles.
  • the small particles are called primary particles and the large particles are called secondary particles. It was observed that the coating layer of the present invention exists simultaneously on the surface of the secondary particles of the high-nickel material and on the grain boundaries of the primary particles, which once again shows that the coating layer evenly covers the surface of the high-nickel material particles.
  • a method for preparing the positive electrode material described in any one of the above aspects comprising the following steps: mixing an organic acid with a non-aqueous solvent to obtain an organic acid solution; adding the high-nickel material to the organic acid solution and stirring to obtain a mixed solution; filtering the mixed solution to obtain a mixture; and vacuum drying, grinding, and sieving the mixture to obtain the positive electrode material; wherein the coating layer is produced by the reaction of the organic acid with LiOH and/or Li2CO3 contained in the high-nickel material.
  • the inventors unexpectedly discovered that by washing the high-nickel material with an organic acid, the organic acid reacts with the residual alkali in the material to form a coating layer covering the surface of the high-nickel material, which can improve the impedance and cycle performance of the material while removing the residual alkali.
  • the pKa of the organic acid is 1-5.
  • the organic acid comprises one or more of maleic acid, acrylic acid, fumaric acid, malonic acid, oxalic acid, malic acid, glycolic acid, succinic acid, citric acid, trisaccharic acid and aconitic acid.
  • the organic acid is one or more of maleic acid, malonic acid and oxalic acid, preferably maleic acid.
  • the non-aqueous solvent includes one or more of methanol, ethanol, isopropanol, ethylene glycol and glycerol.
  • the inventors have found that washing high-nickel materials with maleic acid, malonic acid or oxalic acid, especially maleic acid, can obtain relatively excellent material properties, and using non-aqueous solvents to prepare organic acid solutions helps reduce the impact on material impedance.
  • the mass fraction of the organic acid in the organic acid solution is 0.1wt%-35wt%
  • the mass ratio of the high-nickel material to the organic acid solution is 1:0.2-1:5
  • the molar ratio of the total Li amount in LiOH and/or Li2CO3 contained in the high- nickel material to the organic acid in the organic acid solution is 1:0.1-1:4.
  • the stirring is performed at a speed of 50-500 rpm for 0.1-8 h
  • the vacuum drying is performed at a temperature of 60-150° C. for 0.1-12 h
  • the sieve size used for sieving is 50-500 mesh.
  • the inventors have found that the process conditions of the positive electrode material preparation process have a certain influence on the performance of the prepared material. When the process parameters of the process meet the above ranges, it is conducive to preparing materials with better performance.
  • a lithium-ion secondary battery comprising a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte, wherein the positive electrode sheet comprises a positive electrode material described in any one of the above aspects or prepared by the method described in any one of the above aspects.
  • the high nickel material and lithium ion battery used in the examples were prepared by the following steps.
  • step (3) Use 90 g of the acid-washed high-nickel material prepared in step (3), 5 g of conductive carbon black as a conductive agent, and 5 g of polyvinylidene fluoride (PVDF) as a binder to make an electrode sheet, and use the above electrode sheet to make a half-cell for measuring the electrochemical performance of the battery.
  • PVDF polyvinylidene fluoride
  • the high-nickel material and battery were prepared using the same method as in Example 1, except that maleic acid was replaced with oxalic acid of the same mass.
  • the high-nickel material and battery were prepared using the same method as in Example 1, except that maleic acid was replaced with malonic acid of the same mass.
  • the high-nickel material and battery were prepared using the same method as in Example 1, except that 4 g of maleic acid was used in step (1).
  • the high-nickel material and battery were prepared using the same method as in Example 1, except that ethanol was added to 67 g in step (1).
  • the high-nickel material and battery were prepared using the same method as in Example 1, except that the stirring speed in step (2) was 200 rpm.
  • the high-nickel material and battery were prepared using the same method as in Example 1, except that the drying temperature in step (3) was 80°C.
  • the high-nickel material and battery were prepared using the same method as in Example 1, except that the sieving size in step (3) was 300 mesh.
  • the positive electrode materials prepared according to the embodiments of the present invention were subjected to FTIR, XPS C1s and ToF-SIMS tests, respectively.
  • the peaks in the range of 288-290 eV represent COOR.
  • the fragment peaks of CxHyn - 1OzLin- and Cx - 1Hyn - 1Oz -2Lin- were shown in the ToF- SIMS test.
  • the mass fraction of the coating layer prepared in the embodiment of the present invention in the high-nickel material is 1-10wt%, and the thickness of the coating layer is 1-100nm through electron microscope observation, and it is simultaneously present on the surface of the secondary particles of the high-nickel material and on the grain boundaries of the primary particles.
  • the high-nickel material and battery were prepared using the same method as in Example 1, except that the untreated high-nickel material was directly used to prepare the positive electrode sheet and the battery.
  • the high-nickel material and battery were prepared using the same method as in Example 1, except that the organic acid solution in step (1) was replaced with 100 g of deionized water.
  • a high-nickel material and a battery are prepared using the same method as in Example 1, except that: (4) after step (3), 100 g of the acid-washed high-nickel material obtained in step (3) is added to 100 g of deionized water and steps (2) and (3) are repeated to obtain an acid-washed and water-washed high-nickel material; and (5) an electrode sheet is made using 90 g of the material prepared in step (4), 5 g of conductive carbon black as a conductive agent, and 5 g of polyvinylidene fluoride (PVDF) as a binder, and the electrode sheet is used to make a half-cell.
  • PVDF polyvinylidene fluoride
  • the half-cells in the above-mentioned embodiments and comparative examples were first subjected to a 0.1C cycle test at 25°C for one time, and then the initial impedance was tested. Then, a 1C charge and 5C discharge cycle test was performed at 60°C for 100 times to determine the capacity retention rate of the battery after 100 cycles, and then the post-cycle impedance was tested.
  • the test results are shown in Table 1 below.
  • Figure 2 also shows a graph of the capacity retention rate relative to the number of cycles of Example 1 and Comparative Example 1, in which it can be seen that the positive electrode material according to the present invention is compared with the untreated high-nickel material, the water-washed high-nickel material, and the acid-washed and water-washed high-nickel material.
  • the high-nickel material and the high-nickel material washed with water after pickling have obvious improvements in capacity retention.
  • Figure 4 also shows the ToF-SIMS spectrum of the positive electrode material prepared according to Comparative Example 3. It can be seen that when the acid-washed high-nickel material is washed with water again, the surface of the high-nickel material does not have the coating layer of the present invention.
  • the methods for removing residual alkali on the surface of high-nickel materials in the prior art are to wash the high-nickel material with water, or to wash the high-nickel material after pickling with water again, the method of preparing modified high-nickel material by pickling of the present invention obtains unexpectedly improved impedance growth and capacity retention.
  • Examples 1-3 show that the specific organic acid specified in the present invention can achieve the technical effects of reducing residual alkali, improving impedance growth and capacity retention, among which maleic acid can achieve the best technical effect.
  • Examples 1, 4, and 5 show that the mass fraction of the organic acid in the solution within the specific range specified in the present invention and the mass ratio of the high-nickel material and the organic acid solution can achieve better technical effects.
  • Examples 1 and 6-8 show that the stirring speed, drying temperature, and sieving size within the specific range specified in the present invention can achieve better technical effects.
  • the impedance growth and capacity retention are improved while reducing the residual alkali level.

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Abstract

一种用于锂离子电池的正极材料、用于制备其的方法及包含其的锂离子二次电池。所述正极材料包含高镍材料、以及所述高镍材料的表面上的包覆层，其中所述包覆层包含式(I)的化合物C xH y-nO zLi n(I)和式(II)的化合物C xH y-n-1O zLi n+1(II)，其中x、y、z、n各自独立地为1≤x≤10，2≤y≤20，2≤z≤12，1≤n≤3的整数。

Description

正极材料、用于制备其的方法及包含其的锂离子二次电池 技术领域
本发明涉及锂离子二次电池领域，具体而言，涉及一种用于锂电池的正极材料、用于制备其的方法及包含其的锂离子二次电池。
背景技术
近年来，随着电子技术的不断更新，人们对用于支持电子设备的能源供应的电池装置的需求也在不断增加。现如今，需要能够存储更多电量且能够输出高功率的电池。传统铅酸电池以及镍氢电池等已经不能满足新的电子制品的需求。因此，锂电池引起了人们的广泛关注。在对锂电池的开发过程中，已经较为有效地提高了其容量和性能。
在锂电池技术中，高镍材料由于具有较高的能量密度，是目前正极材料发展的主要方向，被广泛地运用于动力电池领域。但是高镍材料表面的残碱(包括LiOH和Li2CO3)会随着镍含量的提高而升高，导致其加工性能不佳；而且残碱会导致电池的产气，锂杂质越多，产气就越严重，因此，降低高镍材料表面的残碱量成为当今的研究重点。
现在主流的水洗改性的高镍材料表面的残碱确实会有比较大的降低，但是水洗改性的材料表面会有NiO类物质生成，导致电池阻抗增加，并且材料中的晶格锂会析出，造成材料结构不稳定，循环性能明显变差。
发明内容
本发明的主要目的在于提供一种用于锂电池的正极材料、用于制备其的方法及包含其的锂离子二次电池，以解决现有技术中用于降低高镍材料表面的残碱量的方法导致电池阻抗增加和循环性能变差的问题。
为解决上述问题，本发明提供了一种新的高镍材料，该材料表面的残碱量极少，同时表面具有RCOOLi类物质作为包覆层，该包覆层可以稳定材料结构，降低阻抗，材料的循环性能也得到较大提升。
根据本发明的一个方面，本发明提供了一种用于锂离子电池的正极材料，包含高镍材料；以及所述高镍材料的表面上的包覆层，其中所述包覆层包含式(I)的化合物
CxHy-nOzLin     (I)
和式(II)的化合物
CxHy-n-1OzLin+1     (II)，
其中x、y、z、n各自独立地为1≤x≤10，2≤y≤20，2≤z≤12，1≤n≤3的整数。
进一步地，在上述正极材料中，所述式(I)的化合物和所述式(II)的化合物是有机酸的Li盐，所述有机酸具有通式CxHyOz，其中x、y、z各自独立地为1≤x≤10，2≤y≤20，2≤z≤12的整数，所述有机酸含有1-3个羧基和0-1个C＝C双键。
进一步地，在上述正极材料中，所述有机酸包括马来酸、丙烯酸、富马酸、丙二酸、草酸、苹果酸、乙醇酸、丁二酸、柠檬酸、丙三酸和乌头 酸中的一种或多种，优选马来酸、丙二酸和草酸中的一种或多种，最优选马来酸。
进一步地，在上述正极材料中，所述式(I)的化合物在所述包覆层中的摩尔百分比a为50％≤a＜100％，所述式(II)的化合物在所述包覆层中的摩尔百分比b为0％＜b≤50％，优选地1≤a/b≤3。
进一步地，在上述正极材料中，所述包覆层均匀覆盖在所述高镍材料的表面。
进一步地，在上述正极材料中，所述包覆层的厚度为1-100nm，所述包覆层在所述高镍材料中的质量分数为0.1-10wt％，优选1-5wt％。
进一步地，在上述正极材料中，所述包覆层同时存在于所述高镍材料的二次颗粒的表面和一次颗粒的粒界上。
进一步地，在上述正极材料中，所述高镍材料具有通式LiNimMnO2，其中m+n＝1，0.6≤m≤1，0≤n≤0.4，M为Co、Mn、Al、Mg、Ti、Fe、Cu、Zn、Ga、Zr、Mo、Nb和W中的一种或多种。
根据本发明的另一个方面，本发明提供了一种用于制备上述方面中的任一项所述的正极材料的方法，包括以下步骤：将有机酸与非水溶剂混合得到有机酸溶液；将所述高镍材料加入所述有机酸溶液中并搅拌，得到混合溶液；将所述混合溶液进行抽滤，得到混合物；和将所述混合物真空干燥、研磨、过筛后得到所述正极材料；其中，由所述有机酸与所述高镍材料中包含的LiOH和/或Li2CO3的反应产生所述包覆层。
进一步地，在上述方法中，所述有机酸的pKa为1-5。
进一步地，在上述方法中，所述有机酸包括马来酸、丙烯酸、富马酸、丙二酸、草酸、苹果酸、乙醇酸、丁二酸、柠檬酸、丙三酸和乌头酸中的一种或多种。
进一步地，在上述方法中，所述有机酸是马来酸、丙二酸和草酸中的一种或多种，优选马来酸。
进一步地，在上述方法中，所述非水溶剂包括甲醇、乙醇、异丙醇、乙二醇和丙三醇中的一种或多种。
进一步地，在上述方法中，所述有机酸在所述有机酸溶液中的质量分数为0.1wt％-35wt％，所述高镍材料和所述有机酸溶液的质量比为1:0.2-1:5，所述高镍材料含有的LiOH和/或Li2CO3中的总Li量与所述有机酸溶液中的所述有机酸的摩尔比为1:0.1-1:4。
进一步地，在上述方法中，所述搅拌在50-500rpm的速度下进行0.1-8h，所述真空干燥在60-150℃的温度下进行0.1-12h，所述过筛使用的筛尺寸为50-500目。
根据本发明的另一个方面，本发明提供了一种锂离子二次电池，包括正极片、负极片、隔膜以及电解液，所述正极片包含上述方面中任一项所述的或通过上述方面中任一项所述的方法制备的正极材料。
通过本发明的用于锂电池的正极材料、用于制备其的方法及包含其的锂离子二次电池，实现了降低高镍正极材料中的残碱同时改善阻抗和循环性能的效果。
附图说明
构成本申请的一部分的说明书附图用来提供对本发明的进一步理解，本发明的示意性实施例及其说明用于解释本发明，并不构成对本发明的不当限定。在附图中：
图1是根据本发明的实施方式中有机酸与残碱的反应过程的示意图。
图2是显示根据本发明的实施例以及对比例制备的电池的相对于循环次数的循环保持率的图。
图3是根据本发明实施例1制备的正极材料的ToF-SIMS图谱。
图4是根据对比例3制备的正极材料的ToF-SIMS图谱。
具体实施方式
需要说明的是，在不冲突的情况下，本申请中的实施例及实施例中的特征可以相互组合。下面将参考附图并结合实施例来详细说明本申请。
为了使本技术领域的人员更好地理解本申请的方案，下面将结合本申请实施例中的附图，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的实施例，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，都应当属于本申请保护的范围。
如在背景技术部分中所说明的，现有技术使用水洗改性降低高镍材料表面的残碱，但是水洗改性的材料表面会有NiO类物质生成，导致电池阻抗增加，并且材料中的晶格锂会析出，造成材料结构不稳定，循环性能变差。
针对上述问题，本发明提供了一种用于锂电池的正极材料，其中高镍材料经过有机酸溶液洗涤，有机酸与材料表面的残碱发生反应，消除了残碱，同时生成了RCOOLi结构的物质，能够包覆在高镍材料的表面。本发明的高镍正极材料经过了有机酸的洗涤，表面仅残余微量碱性物质，同时具有良好的稳定性，有机酸与碱反应生成的RCOOLi物质可以降低阻抗，循环性能也得到较大提升。
根据本申请的一个典型的实施方式，提供了一种用于锂离子电池的正极材料，包含高镍材料；以及所述高镍材料的表面上的包覆层，其中所述R-Li结构的包覆层包含式(I)的化合物
CxHy-nOzLin   (I)
和式(II)的化合物
CxHy-n-1OzLin+1     (II)，
其中x、y、z、n各自独立地为1≤x≤10，2≤y≤20，2≤z≤12，1≤n≤3的整数。
在优选的实施方式中，所述高镍材料具有通式LiNimMnO2，其中m+n＝1，0.6≤m≤1，0≤n≤0.4，M为Co、Mn、Al、Mg、Ti、Fe、Cu、Zn、Ga、Zr、Mo、Nb和W中的一种或多种。
在本领域中，在制备高镍材料的过程中，会稍微提高锂与金属的比例(即锂盐适当过量)来弥补烧结过程中造成的损失，因此制成的高镍材料中会有Li剩余，主要以Li2O形式存在，其容易与空气中的CO2和H2O反应生成Li2CO3和LiOH。另外，高镍材料中的镍含量越高，代表材料中的LiNiO2越多，而LiNiO2也可以和H2O反应生成LiOH，生成较多的LiOH。
为了减少高镍材料中的残碱，本发明人出乎意料地发现，通过使用特定的有机酸洗涤高镍材料，能够去除高镍材料表面的残碱，同时有机酸与残碱反应生成的化合物能够在高镍材料表面形成RCOOLi物质的包覆层，而根据本发明的上述包覆层能够起到降低阻抗和改善循环性能的效果。
其中，RCOOLi物质是有机酸和碱完全反应的产物(即式(II)的化合物)与不完全反应的产物(即式(I)的化合物)的混合物，当两者同时存在时实现最佳的包覆效果。如果全部RCOOLi物质均是完全反应的产物，则反应会消耗正极材料晶格中的锂，使得材料本身活性的锂减少，从而导致容量的减少。而如果全部RCOOLi物质均是不完全反应的产物，其离子传导性会有所欠缺，阻抗性能就会受到影响。
例如，如图1中所显示的，在残碱与马来酸反应的情况下，会生成如图所示的完全反应产物和不完全反应产物。
在本申请的一些实施方式中，所述式(I)的化合物和所述式(II)的化合物是有机酸的Li盐，所述有机酸具有通式CxHyOz，其中x、y、z各自独立地为1≤x≤10，2≤y≤20，2≤z≤12的整数，所述有机酸含有1-3个羧基和0-1个C＝C双键。
如上所述，本发明的包覆层是有机酸和残锂(包括Li2CO3和LiOH)反应的产物，即有机酸的Li盐，其中有机酸具有通式CxHyOz。发明人还发现，含有1-3个羧基和0-1个C＝C双键的有机酸有助于形成本发明的包覆层。
在本申请的优选实施方式中，该有机酸包括马来酸、丙烯酸、富马酸、丙二酸、草酸、苹果酸、乙醇酸、丁二酸、柠檬酸、丙三酸和乌头酸中的一种或多种，优选马来酸、丙二酸和草酸中的一种或多种，最优选马来酸。
在本申请的一些实施方式中，所述式(I)的化合物在所述包覆层中的摩尔百分比a为50％≤a＜100％，所述式(II)的化合物在所述包覆层中的摩尔百分比b为0％＜b≤50％，优选地1≤a/b≤3。
如上所述，有机酸和碱的反应产生完全反应的产物(即式(II)的化合物)与不完全反应的产物(即式(I)的化合物)。发明人发现，二者之间合适的比例有助于实现最佳的包覆效果。如果上述比例a/b小于1，说明完全反应产物居多，其会额外消耗正极材料晶格中的锂，导致材料容量降低，如果所述比例a/b大于3，说明不完全反应产物居多，其会导致包覆层的离子电导率降低，影响阻抗。
在本申请的一些实施方式中，所述包覆层在FTIR中显示1600-1800cm-1范围内的特征峰，在XPS C1s中显示288-290eV范围内的特征峰，在ToF-SIMS测试中显示CxHy-n-1OzLin -和Cx-1Hy-n-1Oz-2Lin -的碎片峰。所述碎片峰在ToF-SIMS测试的二维成像图谱(又称元素分布图谱、mapping图谱)中显示为均匀覆盖在所述高镍材料的表面。
本发明人对根据本发明制备的正极材料分别进行了FTIR、XPS C1s和ToF-SIMS测试。其中FTIR中1600-1800cm-1范围内的特征峰代表C＝O，XPS中285-287eV的峰代表C＝O，288-290eV的峰代表COOR。因此上述测试均验证了本发明制备的正极材料的包覆层中存在上述式(I)和(II)的化合物，且包覆层均匀覆盖在高镍材料的表面。
在本申请的一些实施方式中，所述包覆层的厚度为1-100nm，在所述高镍材料中的质量分数为0.1-10wt％，优选1-5wt％。在优选的实施方式中，所述包覆层同时存在于所述高镍材料的二次颗粒的表面和一次颗粒的粒界上。
发明人通过测试发现，当包覆层在高镍材料中的质量分数为1-10wt％时，对于材料性能是最为有利的。发明人还通过电子显微镜观察发现，根据本发明的实施方式制备的包覆层的厚度为1-100nm。高镍材料颗粒是由多个小颗粒团聚而成的大颗粒，小颗粒被称为一次颗粒，大颗粒被称为二次颗粒。观察发现，本发明的包覆层同时存在于所述高镍材料的二次颗粒的表面和一次颗粒的粒界上，再次说明包覆层均匀地覆盖高镍材料颗粒表面。
根据本发明的另一个典型的实施方式，提供了一种用于制备上述方面中任一项所述的正极材料的方法，包括以下步骤：将有机酸与非水溶剂混合得到有机酸溶液；将所述高镍材料加入所述有机酸溶液中并搅拌，得到混合溶液；将所述混合溶液进行抽滤，得到混合物；和将所述混合物真空干燥、研磨、过筛后得到所述正极材料；其中由所述有机酸与所述高镍材料中包含的LiOH和/或Li2CO3的反应产生所述包覆层。
如上所述，本发明人出乎意料地发现，通过使用有机酸洗涤高镍材料，使有机酸与材料中的残碱反应形成覆盖高镍材料的表面的包覆层，在去除残碱的同时还能够改善材料的阻抗和循环性能。
在本申请的一些实施方式中，所述有机酸的pKa为1-5。
在优选的实施方式中，所述有机酸包括马来酸、丙烯酸、富马酸、丙二酸、草酸、苹果酸、乙醇酸、丁二酸、柠檬酸、丙三酸和乌头酸中的一种或多种。
在优选的实施方式中，所述有机酸是马来酸、丙二酸和草酸中的一种或多种，优选马来酸。
在本申请的一些实施方式中，所述非水溶剂包括甲醇、乙醇、异丙醇、乙二醇和丙三醇中的一种或多种。
本发明人发现，使用马来酸、丙二酸或草酸，尤其是马来酸进行高镍材料的洗涤能够得到较为优秀的材料性能，而采用非水溶剂制备有机酸溶液有助于减少对材料阻抗的影响。
在本申请的一些实施方式中，所述有机酸在所述有机酸溶液中的质量分数为0.1wt％-35wt％，所述高镍材料和所述有机酸溶液的质量比为1:0.2-1:5，所述高镍材料含有的LiOH和/或Li2CO3中的总Li量与所述有机酸溶液中的所述有机酸的摩尔比为1:0.1-1:4。
发明人发现，当洗涤中使用的有机酸和高镍材料的用量符合上述比例范围时，有利于制备性能更好的材料。其中，当高镍材料和所述有机酸溶液的质量比过低时，溶剂使用多，产生浪费，增加成本；当质量比过高时，高镍正极材料难以在溶液中均匀分散，影响反应的均匀性。
在本申请的一些实施方式中，所述搅拌在50-500rpm的速度下进行0.1-8h，所述真空干燥在60-150℃的温度下进行0.1-12h，所述过筛使用的筛尺寸为50-500目。
发明人发现，正极材料制备过程的工艺条件对于制备的材料的性能存在一定影响。其中当过程的工艺参数符合上述范围时，有利于制备性能更好的材料。
根据本发明的另一个典型的实施方式，提供了一种锂离子二次电池，包括正极片、负极片、隔膜以及电解液，所述正极片包含上述方面中任一项所述的或通过上述方面中任一项所述的方法制备的正极材料。
以下结合具体实施例对本发明作进一步详细描述，这些实施例不应理解为用来限制本发明所要求保护的范围。
实施例
实施例1
通过以下步骤制备实施例中使用的高镍材料和锂离子电池。
(1)称取2g马来酸倒进烧杯中，加入乙醇至100g，搅拌1h得到马来酸溶液；(2)称取100g高镍正极材料(LiNi0.8Co0.1Al0.1O2)，加入步骤(1)中的溶液中，在350rpm下搅拌1h，得到混合溶液；(3)将步骤(2)的混合溶液抽滤，得到的固体物质放进真空干燥箱中120℃干燥8h，研磨过筛(200目)后得到酸洗后的高镍材料；(4)利用步骤(3)中制备出的酸洗后的高镍材料90g、5g作为导电剂的导电炭黑和5g作为粘结剂的聚偏氟乙烯(PVDF)制作成电极片，并且利用上述电极片制作成半电池，用于测量电池的电化学性能。
实施例2
使用与实施例1相同的方法制备高镍材料和电池，区别在于将马来酸替换为相同质量的草酸。
实施例3
使用与实施例1相同的方法制备高镍材料和电池，区别在于将马来酸替换为相同质量的丙二酸。
实施例4
使用与实施例1相同的方法制备高镍材料和电池，区别在于步骤(1)中使用的马来酸为4g。
实施例5
使用与实施例1相同的方法制备高镍材料和电池，区别在于步骤(1)中加入乙醇至67g。
实施例6
使用与实施例1相同的方法制备高镍材料和电池，区别在于步骤(2)中搅拌速度为200rpm。
实施例7
使用与实施例1相同的方法制备高镍材料和电池，区别在于步骤(3)中干燥温度为80℃。
实施例8
使用与实施例1相同的方法制备高镍材料和电池，区别在于步骤(3)中过筛尺寸为300目。
如上文所述，对根据本发明实施例制备的正极材料分别进行了FTIR、XPS C1s和ToF-SIMS测试。其中FTIR中显示1600-1800cm-1范围内的特征峰，代表C＝O，XPS中显示285-287eV的峰，代表C＝O，288-290eV的峰代表COOR。在ToF-SIMS测试中显示CxHy-n-1OzLin -和Cx-1Hy-n-1Oz-2Lin -的碎片峰。该碎片峰在ToF-SIMS测试的二维成像图谱中显示为均匀覆盖在高镍材料的表面(参见图3)。因此上述测试验证了本发明实施例制备的正极材料的包覆层中存在上述式(I)和(II)的化合物，且包覆层均匀覆 盖在高镍材料的表面。同样通过测试发现，本发明实施例制备的包覆层在高镍材料中的质量分数为1-10wt％，通过电子显微镜观察发现包覆层的厚度为1-100nm，且同时存在于所述高镍材料的二次颗粒的表面和一次颗粒的粒界上。
对比例1
使用与实施例1相同的方法制备高镍材料和电池，区别在于直接使用未处理的高镍材料制备正极片和电池。
对比例2
使用与实施例1相同的方法制备高镍材料和电池，区别在于将步骤(1)中的有机酸溶液替换为100g去离子水。
对比例3
使用与实施例1相同的方法制备高镍材料和电池，区别在于，(4)在步骤(3)之后，将步骤(3)得到的酸洗后的高镍材料100g加入100g去离子水中并重复步骤(2)和步骤(3)，得到酸洗后水洗的高镍材料；(5)利用步骤(4)中制备出的材料90g、5g作为导电剂的导电炭黑和5g作为粘结剂的聚偏氟乙烯(PVDF)制作成电极片，并且利用上述电极片制作成半电池。
将上述实施例及对比例中的半电池首先在25℃下进行0.1C的循环测试1次，结束后测试初始阻抗，然后在60℃下进行1C充电5C放电的循环测试100次，确定电池的100次循环之后的容量保持率，结束后测试循环后阻抗。测试结果如下表1所示。
表1
*阻抗增长倍数＝循环后阻抗/初期阻抗
在表1的结果中，通过实施例1-8与对比例1-3的对比可以看出，根据本发明的正极材料以及根据本发明的方法制备的正极材料，其中高镍材料表面上具有包覆层，包覆层包含式(I)和式(II)的化合物，相比未处理的高镍材料、水洗处理的高镍材料以及酸洗后水洗的高镍材料，具有较低的残碱水平，并且在阻抗增长和容量保持率方面获得明显改善。这种表面具有特定组成的包覆层的高镍正极材料在现有技术中没有描述。此外，图2也显示了实施例1与对比例1的相对于循环次数的容量保持率的图，其中可以看出，根据本发明的正极材料相比未处理的高镍材料、水洗处理 的高镍材料以及酸洗后水洗的高镍材料在容量保持率具有明显的改善。图4还显示了根据对比例3制备的正极材料的ToF-SIMS图谱，可以看出，在对酸洗的高镍材料再进行水洗的情况下，高镍材料的表面不具有本发明的包覆层。考虑到现有技术中用于去除高镍材料的表面残碱的方法均是对高镍材料进行水洗处理，或者对酸洗后的高镍材料再进行水洗处理，本发明的通过酸洗制备改性高镍材料的方法获得了出乎意料的改善的阻抗增长和容量保持率。
此外，实施例1-3显示了本发明规定的特定的有机酸能够实现降低残碱、改善阻抗增长和容量保持率的技术效果，其中马来酸能够实现最优的技术效果。实施例1、4、5显示了本发明规定的特定范围内的有机酸在溶液中的质量分数以及高镍材料和有机酸溶液的质量比能够实现更好的技术效果。实施例1和6-8显示了本发明规定的特定范围内的搅拌速度、干燥温度和过筛尺寸能够实现更好的技术效果。
总之，通过使用根据本发明的正极材料以及根据本发明的方法制备的正极材料，与根据现有技术的正极材料相比，在降低残碱水平的同时在阻抗增长和容量保持率方面获得了改善。
以上所描述的仅为本发明的优选实施例，并不用于限制本发明，对于本领域的技术人员来说，本发明可以有各种更改和变化。凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (16)

  1. 一种用于锂离子电池的正极材料，包含：
    高镍材料；以及
    所述高镍材料的表面上的包覆层，其中所述包覆层包含：
    式(I)的化合物
    CxHy-nOzLin  (I)
    和式(II)的化合物
    CxHy-n-1OzLin+1  (II)，
    其中x、y、z、n各自独立地为1≤x≤10，2≤y≤20，2≤z≤12，1≤n≤3的整数。
  2. 根据权利要求1所述的正极材料，其特征在于，所述式(I)的化合物和所述式(II)的化合物是有机酸的Li盐，所述有机酸具有通式CxHyOz，其中x、y、z各自独立地为1≤x≤10，2≤y≤20，2≤z≤12的整数，所述有机酸含有1-3个羧基和0-1个C＝C双键。
  3. 根据权利要求2所述的正极材料，其特征在于，所述有机酸包括马来酸、丙烯酸、富马酸、丙二酸、草酸、苹果酸、乙醇酸、丁二酸、柠檬酸、丙三酸和乌头酸中的一种或多种，优选马来酸、丙二酸和草酸中的一种或多种，最优选马来酸。
  4. 根据权利要求1所述的正极材料，其特征在于，所述式(I)的化合物在所述包覆层中的摩尔百分比a为50％≤a＜100％，所述式(II)的化合物在所述包覆层中的摩尔百分比b为0％＜b≤50％，优选地1≤a/b≤3。
  5. 根据权利要求1所述的正极材料，其特征在于，所述包覆层均匀覆盖在所述高镍材料的表面。
  6. 根据权利要求1所述的正极材料，其特征在于，所述包覆层的厚度为1-100nm，所述包覆层在所述正极材料中的质量分数为0.1-10wt％，优选1-5wt％。
  7. 根据权利要求1所述的正极材料，其特征在于，所述包覆层同时存在于所述高镍材料的二次颗粒的表面和一次颗粒的粒界上。
  8. 根据权利要求1所述的正极材料，其特征在于，所述高镍材料具有通式LiNimMnO2，其中m+n＝1，0.6≤m≤1，0≤n≤0.4，M为Co、Mn、Al、Mg、Ti、Fe、Cu、Zn、Ga、Zr、Mo、Nb和W中的一种或多种。
  9. 一种用于制备权利要求1-8中任一项所述的正极材料的方法，包括以下步骤：
    将有机酸与非水溶剂混合得到有机酸溶液；
    将所述高镍材料加入所述有机酸溶液中并搅拌，得到混合溶液；
    将所述混合溶液进行抽滤，得到混合物；和
    将所述混合物真空干燥、研磨、过筛后得到所述正极材料；
    其中，由所述有机酸与所述高镍材料中包含的LiOH和/或Li2CO3的反应产生所述包覆层。
  10. 根据权利要求9所述的方法，其特征在于，所述有机酸的pKa为1-5。
  11. 根据权利要求9或10所述的方法，其特征在于，所述有机酸包括马来酸、丙烯酸、富马酸、丙二酸、草酸、苹果酸、乙醇酸、丁二酸、柠檬酸、丙三酸和乌头酸中的一种或多种。
  12. 根据权利要求11所述的方法，其特征在于，所述有机酸是马来酸、丙二酸和草酸中的一种或多种，优选马来酸。
  13. 根据权利要求9所述的方法，其特征在于，所述非水溶剂包括甲醇、乙醇、异丙醇、乙二醇和丙三醇中的一种或多种。
  14. 根据权利要求9所述的方法，其特征在于，所述有机酸在所述有机酸溶液中的质量分数为0.1wt％-35wt％，所述高镍材料和所述有机酸溶液的质量比为1:0.2-1:5，所述高镍材料含有的LiOH和/或Li2CO3中的总Li量与所述有机酸溶液中的所述有机酸的摩尔比为1:0.1-1:4。
  15. 根据权利要求9所述的方法，其特征在于，所述搅拌在50-500rpm的速度下进行0.1-8h，所述真空干燥在60-150℃的温度下进行0.1-12h，所述过筛使用的筛尺寸为50-500目。
  16. 一种锂离子二次电池，包括正极片、负极片、隔膜以及电解液，其特征在于，所述正极片包含权利要求1-8中任一项所述的或通过权利要求9-15中任一项所述的方法制备的正极材料。
PCT/CN2023/114270 2022-10-31 2023-08-22 正极材料、用于制备其的方法及包含其的锂离子二次电池 WO2024093457A1 (zh)

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