A metal oxide precursor and its preparation method and application

Abstract

The present invention discloses a metal oxide precursor and its preparation method and application. The precursor contains nickel, manganese and element M, and element M includes one or more of cobalt and aluminum. The preparation method comprises: preparing a mixed metal salt solution with a total metal ion concentration of 2-5 mol / L; spraying the mixed metal salt solution into a high-temperature pyrolysis furnace in the form of an aerosol to carry out a spray pyrolysis reaction; roasting the spray pyrolysis product in an oxygen-containing atmosphere for 1-4 hours at a roasting temperature of 500-700°C; dispersing the roasted product in an acidic aqueous solution, hydrothermally reacting it at 150-250°C for 1-6 hours, filtering and washing it until the filtrate conductivity is less than 50μS / cm; drying the washed product and pulverizing it with an airflow to obtain a metal oxide precursor. When used, the metal oxide precursor is mixed with a lithium source and sintered to obtain a ternary positive electrode material. The present invention removes impurities by combining low-temperature roasting and acidic hydrothermal treatment, optimizes the structure and improves the positive electrode performance.

Description

Technical Field

[0001] The present invention relates to the technical field of novel materials for ternary precursor batteries, and in particular to a metal oxide precursor and a preparation method and application thereof. Background Art

[0002] At this critical juncture of energy transition, innovations in the preparation of ternary oxide precursors, core raw materials for ternary cathode materials in lithium-ion batteries, are crucial for improving battery performance and reducing production costs. Spray pyrolysis technology, with its significant advantages such as zero wastewater discharge, low energy consumption, a short production process, and high output, has attracted significant research investment in recent years. Compared to traditional co-precipitation ternary precursor technology, spray pyrolysis offers significant competitiveness in terms of manufacturing costs.

[0003] However, this technology still faces severe challenges in practical application. The products generated by the spray pyrolysis process have the problem of excessively high levels of impurities such as chlorine and sulfur. The residues of these impurities not only generate harmful gases and corrode the kiln during the manufacturing process of the positive electrode material, but also damage the structural integrity and electrochemical performance of the ternary positive electrode material. In addition, key indicators such as the particle size distribution of the precursor (such as D50, Dmax), tap density and specific surface area also have a profound impact on the performance of the ternary positive electrode material. An unreasonable particle size distribution will make it difficult to achieve dense stacking of the material during the electrode preparation process, reduce the compaction density of the electrode, and thus affect the energy density of the battery. Insufficient tap density limits the loading amount of active material per unit volume, which is also not conducive to improving the energy storage capacity of the battery. A specific surface area that is too large or too small will affect the interfacial reaction between the material and the electrolyte, and have an adverse effect on the charge and discharge kinetics of the battery.

[0004] Therefore, how to effectively reduce the impurity content and precisely control various key performance indicators in the process of preparing ternary metal oxide precursors using spray pyrolysis technology has become a core problem that needs to be overcome urgently in this field. Summary of the Invention

[0005] The purpose of the present invention is to provide a metal oxide precursor and a preparation method and application thereof.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A metal oxide precursor comprises nickel, manganese and element M; based on the total molar number of the metal elements, the molar proportion of the nickel element is 55-85 mol%, the molar proportion of the manganese element is 0-35 mol%, and the molar proportion of the element M is 0-15 mol%. The element M comprises one or more of cobalt and aluminum.

[0008] In the above solution, the element M may also include zirconium, lanthanum, cerium, magnesium, and calcium.

[0009] Further technical solutions, the D50 of the precursor is 1.0~4.0μm, Dmax≤15μm; chlorine content ≤100ppm, sulfur content ≤300ppm; specific surface area is 6-12m 2 / g, tap density is 1.45~2.05g / cm 3 .

[0010] A further technical solution is that when the element M is cobalt, the chemical formula is Ni x Mn y Co z O n ;

[0011] When the element M is aluminum, the chemical formula is Ni x Mn y Al z O n ;

[0012] Where, 0.55≤x≤0.85, 0≤y≤0.35, 0≤z≤0.15, x + y + z = 1;

[0013] n=∑(metal ion oxidation state×atomic ratio) / 2, that is, n is uniquely determined by the oxidation state combination and charge balance of the metal ions.

[0014] Furthermore, the present invention also discloses a method for preparing a metal oxide precursor, which is used to prepare the metal oxide precursor; the preparation method comprises:

[0015] Step 1: dissolving the metal salt in deionized water at a molar ratio, and adding a water-soluble dispersant and additives to prepare a mixed metal salt solution with a total metal ion concentration of 2-5 mol / L;

[0016] Step 2: spraying the mixed metal salt solution into a high-temperature pyrolysis furnace in the form of aerosol to perform a spray pyrolysis reaction;

[0017] Step 3: calcining the spray pyrolysis product in an oxygen-containing atmosphere for 1-4 hours at a calcination temperature of 500-700°C;

[0018] Step 4: Disperse the product of step 3 in an acidic aqueous solution, conduct a hydrothermal reaction at 150-250° C. for 1-6 hours, filter press, and wash with deionized water until the filtrate conductivity is less than 50 μS / cm;

[0019] Step 5: Dry the washed product at 120-180° C. and grind it by air flow to obtain a metal oxide precursor.

[0020] According to a further technical solution, in step 1, the metal salts in the mixed metal salt solution include nickel salts, manganese salts and M salts, and the M salts include cobalt salts and / or aluminum salts;

[0021] The nickel salt is selected from at least one of nickel chloride and nickel sulfate; the manganese salt is selected from at least one of chloride and sulfate; the cobalt salt is selected from at least one of cobalt chloride and cobalt sulfate; and the aluminum salt is selected from at least one of aluminum chloride and aluminum sulfate.

[0022] According to a further technical solution, in step 1, the dispersant is at least one of polyacrylic acid, polyvinyl pyrrolidone, polymaleic anhydride, carboxymethyl chitosan, and polyethylene glycol, and the added amount is 0.5-3% of the total mass of the metal salt.

[0023] According to a further technical solution, in step 1, the additive is at least one of citric acid, ammonium citrate, tartaric acid, and sulfosalicylic acid, and the added molar amount is 1-10% of the total molar number of metal ions.

[0024] According to a further technical solution, in step 2, the droplet D50 of the aerosolized mixed metal salt solution is 30-200 μm;

[0025] The high-temperature pyrolysis furnace has a top temperature of 150-350°C, a pyrolysis temperature in the furnace of 650-950°C, and a bottom temperature of 450-700°C. At the top of the furnace (150-350°C), atomized droplets undergo evaporation, crystallization, and drying reactions. At the furnace's inner temperature of 650-950°C, thermal decomposition occurs to produce metal oxides. At the bottom of the furnace (450-700°C), high-temperature dechlorination occurs.

[0026] According to a further technical solution, in step three, the oxygen-containing atmosphere is air or a nitrogen-oxygen mixture with an oxygen volume ratio of 20-50%.

[0027] In a further technical solution, in step 4, the pH value of the acidic aqueous solution at 25° C. is 1.5-6.0, and the acid used is at least one of sulfuric acid, nitric acid, and acetic acid;

[0028] The hydrothermal reaction is carried out in a hydrothermal reactor with a filling degree of 60-80%. The solid-liquid ratio of the hydrothermal impurity removal process is 1:(1-4), and the washing water temperature is 50-80°C.

[0029] Furthermore, the present invention also discloses an application of a metal oxide precursor, wherein the metal oxide precursor is mixed with a lithium source and sintered to produce a ternary positive electrode material.

[0030] The terms “include”, “including”, “have”, etc. used in this document are open-ended terms, meaning including but not limited to.

[0031] Unless otherwise noted, the terms used herein generally have their ordinary meanings in the art, in the context of this application, and in the specific context. Certain terms used to describe this application are discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art regarding the description of this application.

[0032] The working principle and advantages of the present invention are as follows:

[0033] The present invention provides a preparation method for producing ternary metal oxides with low impurity content by spray pyrolysis. Compared with the existing technology, the present invention significantly reduces the content of impurities such as chlorine and sulfur in the pyrolysis products by optimizing the process steps, thereby improving the quality of the ternary metal oxides.

[0034] This invention significantly reduces residual Cl⁻ and SO⁻ in the product through a "low-temperature roasting-acidic hydrothermal synergistic impurity removal" process. Specifically, this involves spray pyrolysis of a chloride solution containing a dispersant / complexing agent, followed by low-temperature roasting and acidic hydrothermal impurity removal. The final product contains Cl⁻ ≤ 100 ppm and S ≤ 300 ppm.

[0035] In the method for preparing the metal oxide precursor of the present invention, the calcination treatment in step three and the hydrothermal reaction in step four are the core steps for achieving low impurity content and improving product quality.

[0036] In the ternary oxide formed by spray pyrolysis, chlorine and sulfur impurities are dissolved in the form of compounds inside the crystal lattice. Through low-temperature calcination in an oxygen-containing atmosphere, the chlorine- and sulfur-containing compounds in the crystal lattice undergo oxidative decomposition reactions with oxygen to generate volatile gases. The lower temperature causes only limited migration of precursor atoms, which can not only repair lattice defects and enhance the stability of the particle structure, but also avoid excessive sintering caused by high temperature, thereby preventing the particle specific surface area from decreasing and the activity from decreasing. This low-temperature calcination process precisely targets impurities within the crystal lattice, efficiently removing chlorine and sulfur while maintaining the activity of the precursor, while reducing energy consumption and cost. In addition, the loose porous structure formed after calcination is conducive to the penetration of the hydrothermal solution in step four, further improving the efficiency of impurity removal, and laying a foundation for high-quality raw materials for the preparation of high-performance positive electrode materials.

[0037] After low-temperature calcination, some chlorine and sulfur impurities still adhere to the precursor surface. During the hydrothermal process, the high-temperature, high-pressure, acidic aqueous solution significantly increases ionic activity, allowing hydrogen ions in the solution to fully react with the chlorine and sulfur compounds on the precursor surface, converting them into soluble substances. Simultaneously, the high-temperature, high-pressure environment significantly enhances the penetration of the acidic solution, allowing it to penetrate deep into the precursor particles. Chlorine and sulfur impurities previously trapped within the particles are gradually dislodged by the acidic solution's erosion and dissolution. These impurities then diffuse into the external solution through microchannels formed by the hydrothermal process, achieving deep impurity removal. This process effectively addresses the difficulty of removing impurities entrained within the precursor, significantly reducing residual chlorine and sulfur. This deep impurity removal not only improves precursor purity but also avoids the degradation of cathode material performance caused by residual impurities. Furthermore, the improved particle structure achieved by the hydrothermal process further optimizes the precursor's processability, ensuring efficient subsequent cathode material sintering while reducing production costs.

[0038] Compared with the prior art, the preparation method of the present invention has reliable process, simple operation and is easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Attachment Figure 1 This is a scanning electron microscope image of the spray-pyrolyzed oxide precursor of Example 1 of the present invention;

[0040] Attachment Figure 2 This is a scanning electron microscope image of the spray-pyrolyzed oxide precursor of Comparative Example 1 of the present invention;

[0041] Attachment Figure 3 The graph shows the particle size distribution of the oxides obtained in Example 1 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0042] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0043] The present invention will be clearly illustrated below with drawings and detailed descriptions. After understanding the embodiments of the present invention, any person skilled in the art will be able to make changes and modifications based on the techniques taught by the present invention without departing from the spirit and scope of the present invention.

[0044] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. Example

[0045] 1. Preparation of mixed solution: Weigh nickel chloride, manganese chloride, and cobalt chloride, and dissolve them in deionized water at a molar ratio of nickel, manganese, and cobalt of x:y:z = 0.6:0.3:0.1 to prepare a mixed metal salt solution with a total metal ion concentration of 3 mol / L.

[0046] Polyethylene glycol accounting for 1% of the total mass of the metal salt is added as a water-soluble dispersant, and ammonium citrate with a total molar number of metal ions of 0.1 is added, and the mixture is stirred evenly to fully dissolve and mix the components.

[0047] 2. Spray pyrolysis: The mixed metal salt solution is sprayed into a high-temperature pyrolysis furnace by using a gas atomization device. The top temperature of the pyrolysis furnace is set to 250°C, the pyrolysis temperature in the furnace is 800°C, and the bottom temperature of the furnace is 550°C.

[0048] 3. Calcination: The product obtained by spray pyrolysis was placed in a calcination furnace in an air atmosphere and calcined at 600°C for 1 hour.

[0049] 4. Hydrothermal impurity removal: Disperse the calcined product in a sulfuric acid solution with a pH of 4.0. Control the filling degree of the hydrothermal reactor to 65% and set the solid-liquid ratio to 1:1. Place the reactor in a hydrothermal reaction at 180°C for 2 hours.

[0050] After the reaction is completed, filter pressing is performed to separate the solid product and the solution, and the solid product after filter pressing is washed multiple times with 60° C. deionized water until the conductivity of the filtrate is less than 50 μS / cm.

[0051] 5. Post-treatment: The washed product is then dried at 150°C and finally pulverized by air flow to obtain a metal oxide precursor with the chemical formula Ni 0.6 Mn 0.3 Co 0.1 O 3.4 / 3 . Example

[0052] 1. Preparation of mixed solution: Weigh nickel chloride, manganese chloride, and cobalt chloride, and dissolve them in deionized water at a molar ratio of nickel, manganese, and cobalt of x:y:z = 0.70:0.22:0.08 to prepare a mixed metal salt solution with a total metal ion concentration of 3.5 mol / L.

[0053] Polymaleic anhydride accounting for 1% of the total mass of the metal salt was added as a water-soluble dispersant, and tartaric acid with a total molar number of 0.1 was added, and the mixture was stirred evenly to fully dissolve and mix the components.

[0054] 2. Spray pyrolysis: The mixed metal salt solution is sprayed into a high-temperature pyrolysis furnace by using a gas atomization device. The top temperature of the pyrolysis furnace is 300°C, the pyrolysis temperature in the furnace is 850°C, and the bottom temperature is 600°C.

[0055] 3. Calcination: The product obtained by spray pyrolysis was placed in a calcination furnace in an air atmosphere and calcined at 600°C for 2 hours.

[0056] 4. Hydrothermal Impurity Removal: Disperse the calcined product in a sulfuric acid solution with a pH of 4.0. Set the hydrothermal reactor to 60% fill and a solid-to-liquid ratio of 1:2. Incubate the reaction at 200°C for 4 hours. After impurity removal, filter press the product. Wash the filtered product with 60°C deionized water until the filtrate conductivity is <50μS / cm.

[0057] 5. Post-processing: The filtered product is dried at 160°C and finally pulverized by air flow to obtain a metal oxide precursor with the chemical formula of Ni 0.70 Mn 0.22 Co 0.08 O 1.1 . Example

[0058] 1. Preparation of mixed solution: Weigh nickel sulfate, manganese sulfate, and cobalt sulfate, and dissolve them in deionized water at a molar ratio of nickel, manganese, and cobalt of 0.65:0.25:0.10 to prepare a mixed metal salt solution with a total metal ion concentration of 2.2 mol / L.

[0059] Carboxymethyl chitosan accounting for 1% of the total mass of the metal salt is added as a water-soluble dispersant, and sulfosalicylic acid with a total molar number of 0.1 is added, and the mixture is stirred evenly to fully dissolve and mix the components.

[0060] 2. Spray pyrolysis: The mixed metal salt solution is sprayed into a high-temperature pyrolysis furnace by using a gas atomization device. The top temperature of the pyrolysis furnace is 300°C, the pyrolysis temperature in the furnace is 920°C, and the bottom temperature is 650°C.

[0061] 3. Calcination: The product obtained by spray pyrolysis was placed in a calcination furnace in an air atmosphere and calcined at 650°C for 2 hours.

[0062] 4. Hydrothermal Impurity Removal: Disperse the calcined product in a nitric acid solution with a pH of 3.0. Set the hydrothermal reactor to 60% fill and a solid-to-liquid ratio of 1:2. Incubate the reaction at 220°C for 4 hours. After impurity removal, filter press the product. Wash the filtered product with 60°C deionized water until the filtrate conductivity is <50 μS / cm.

[0063] 5. Post-processing: The filtered product is dried at 160°C and finally pulverized by air flow to obtain a metal oxide precursor with the chemical formula of Ni 0.65 Mn 0.25 Co 0.10 O 3.35 / 3 .

[0064] Comparative Example 1

[0065] 1. Mixed solution preparation: As in Example 1, a mixed metal salt solution with a total metal ion concentration of 3 mol / L and a molar ratio of nickel, manganese, and cobalt of 0.6:0.3:0.1 was prepared. Polyethylene glycol accounting for 1% of the total mass of the metal salt was added as a water-soluble dispersant. Ammonium citrate with a total molar number of metal ions of 0.1 was added and stirred evenly to fully dissolve and mix the components.

[0066] 2. Spray pyrolysis: The same atomization conditions and pyrolysis furnace temperature settings as in Example 1 were used to perform spray pyrolysis to obtain a primary product of a metal oxide precursor.

[0067] 3. Post-processing: The spray pyrolysis product is directly subjected to air flow pulverization to obtain a metal oxide precursor with the chemical formula of Ni 0.6 Mn 0.3 Co 0.1 O 3.4 / 3 .

[0068] Comparative Example 2

[0069] 1. Mixed solution preparation: As in Example 2, a mixed metal salt solution with a total metal ion concentration of 3 mol / L and a molar ratio of nickel, manganese, and cobalt of 0.7:0.2:0.1 was prepared. Polymaleic anhydride accounting for 1% of the total mass of the metal salt was added as a water-soluble dispersant. Tartaric acid with a total molar number of 0.1 was added and stirred evenly to fully dissolve and mix the components.

[0070] 2. Spray pyrolysis: The same atomization conditions and pyrolysis furnace temperature settings as in Example 2 were used to perform spray pyrolysis to obtain a primary product of a metal oxide precursor.

[0071] 3. Calcination: The product obtained by spray pyrolysis was placed in a calcination furnace in an air atmosphere and calcined at 450°C for 2 hours.

[0072] 4. Hydrothermal Impurity Removal: Disperse the calcined product in a sulfuric acid solution with a pH of 4.0. Control the hydrothermal reactor to a 65% fill level and a 1:1 solid-to-liquid ratio. Allow the reactor to react at 120°C for 2 hours. After the reaction, perform a filter press to separate the solid product from the solution. Wash the filtered solid product multiple times with 60°C deionized water until the filtrate conductivity is <50 μS / cm.

[0073] 5. Post-treatment: The washed product is dried at 150°C and finally pulverized by air flow to obtain a metal oxide precursor with the chemical formula of Ni 0.70 Mn 0.22 Co 0.08 O 1.1 .

[0074] The metal oxides prepared in Examples 1-2 and Comparative Examples 1-2 were tested and characterized, and their physical and chemical data are shown in Table 1:

[0075] Table 1 Physical and chemical data of metal oxides

[0076]

[0077] The metal oxides prepared in the above Examples 1-3 and Comparative Examples 1-2 were mixed with a lithium source and sintered to prepare a ternary positive electrode material.

[0078] The positive electrode material, conductive agent and binder PVDF were mixed into a slurry in a mass ratio of 96:2:2 and coated on aluminum foil to make a positive electrode sheet. Metal lithium sheet was used as the negative electrode sheet and assembled into a button battery. The charge and discharge cycle voltage was 3.0~4.45V. The first week charge and discharge capacity was tested at a current density of 0.1C, and the capacity retention rate was tested at a current density of 1C for 50 weeks.

[0079] Table 2 Performance of positive electrode materials

[0080]

[0081] Comparing the data of each instance in Table 1, we can see that:

[0082] In Examples 1-3, due to the use of a low-temperature calcination and acidic hydrothermal synergistic impurity removal process, chlorine and sulfur impurities in the lattice and particle surface were effectively removed. At the same time, Dmax was reduced through crystallization reconstruction, and the particle size distribution and microstructure were optimized. Therefore, the precursor impurity content was low (Cl ≤ 100ppm, S ≤ 300ppm), and the specific surface area (BET) and tap density (TD) were in the ideal range. The prepared ternary positive electrode material exhibited excellent electrochemical performance, with the first discharge specific capacity exceeding 200mAh / g at 0.1C, and the capacity retention rate of 50 weeks at 1C reaching more than 97%.

[0083] Comparative Example 1, however, did not undergo calcination and hydrothermal treatment, resulting in significant residual chlorine and sulfur impurities (Cl reaching 897 ppm and S reaching 554 ppm), a high Dmax of 17.627 μm, and uneven particle size distribution. This resulted in a first-cycle efficiency of only 89.6% for the cathode material, and a 50-cycle capacity retention rate of only 95.6% at 1C, significantly lower than that of the examples. Furthermore, although Comparative Example 2 underwent calcination and hydrothermal treatment, the low calcination temperature and suboptimal hydrothermal conditions resulted in incomplete impurity removal (Cl 289 ppm and S 377 ppm), resulting in a still-large Dmax of 14.748 μm. This also compromised the charge-discharge performance of the cathode material, resulting in a capacity retention rate of only 95.3%.

[0084] In summary, the present invention realizes the core steps of lattice impurity removal and crystal reconstruction through low-temperature calcination and deep removal of surface impurities by acidic hydrothermal method, significantly reducing the content of impurities such as chlorine and sulfur in the pyrolysis products, optimizing the particle size distribution and structure of the precursor, and thus greatly improving the charge and discharge capacity, first efficiency and cycle stability of the positive electrode material, effectively solving the performance defects of the ternary precursor prepared by spray pyrolysis technology.

[0085] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A method for preparing a metal oxide precursor, characterized in that: The precursor contains nickel, manganese, and element M; Based on the total molar number of metal elements, the molar proportion of nickel element is 55-85 mol%, the molar proportion of manganese element is 0-35 mol%, and the molar proportion of element M is 0-15 mol%, and the element M includes one or more of cobalt and aluminum; The preparation method comprises: Step 1: dissolving the metal salt in deionized water at a molar ratio, and adding a water-soluble dispersant and additives to prepare a mixed metal salt solution with a total metal ion concentration of 2-5 mol / L; The dispersant is at least one of polyacrylic acid, polyvinyl pyrrolidone, polymaleic anhydride, carboxymethyl chitosan, and polyethylene glycol, and the added amount is 0.5-3% of the total mass of the metal salt; The additive is at least one of citric acid, ammonium citrate, tartaric acid, and sulfosalicylic acid, and the added molar amount is 1-10% of the total molar number of metal ions; Step 2: spraying the mixed metal salt solution into a high-temperature pyrolysis furnace in the form of aerosol to perform a spray pyrolysis reaction; Step 3: calcining the spray pyrolysis product in an oxygen-containing atmosphere for 1-4 hours at a calcination temperature of 500-700°C; Step 4: Disperse the product of step 3 in an acidic aqueous solution, conduct a hydrothermal reaction at 150-250° C. for 1-6 hours, filter press, and wash with deionized water until the filtrate conductivity is less than 50 μS / cm; Step 5: Dry the washed product at 120-180° C. and grind it by air flow to obtain a metal oxide precursor.

2. The method for preparing a metal oxide precursor according to claim 1, wherein: In step 1, the metal salts in the mixed metal salt solution include nickel salts, manganese salts and M salts, and the M salts include cobalt salts and / or aluminum salts; The nickel salt is selected from at least one of nickel chloride and nickel sulfate; The manganese salt is selected from at least one of chloride and sulfate; The cobalt salt is selected from at least one of cobalt chloride and cobalt sulfate; The aluminum salt is selected from at least one of aluminum chloride and aluminum sulfate.

3. The method for preparing a metal oxide precursor according to claim 1, wherein: In step 2, the droplet D50 of the atomized mixed metal salt solution is 30-200 μm; The top temperature of the high-temperature pyrolysis furnace is 150-350°C, the pyrolysis temperature in the furnace is 650-950°C, and the bottom temperature is 450-700°C.

4. The method for preparing a metal oxide precursor according to claim 1, wherein: In step 3, the oxygen-containing atmosphere is air or a nitrogen-oxygen mixture with an oxygen volume ratio of 20-50%.

5. The method for preparing a metal oxide precursor according to claim 1, wherein: In step 4, the pH value of the acidic aqueous solution at 25° C. is 1.5-6.0, and the acid used is at least one of sulfuric acid, nitric acid, and acetic acid; The hydrothermal reaction is carried out in a hydrothermal reactor with a filling degree of 60-80%. The solid-liquid ratio of the hydrothermal impurity removal process is 1:(1-4), and the washing water temperature is 50-80°C.

6. A metal oxide precursor, characterized in that: The metal oxide precursor is prepared by the preparation method of any one of claims 1 to 5, wherein the precursor has a D50 of 1.0 to 4.0 μm, a Dmax of ≤15 μm, a chlorine content of ≤100 ppm, a sulfur content of ≤300 ppm, and a specific surface area of ​​6 to 12 m 2 / g, tap density is 1.45~2.05g / cm 3 .

7. The metal oxide precursor according to claim 6, wherein: When the element M is cobalt, the chemical formula is Ni x Mn y Co z O n ; When the element M is aluminum, the chemical formula is Ni x Mn y Al z O n ; Where, 0.55≤x≤0.85, 0≤y≤0.35, 0≤z≤0.15, x + y + z = 1; n = ∑(metal ion oxidation state × atomic ratio) / 2.

8. An application of a metal oxide precursor, characterized in that: The metal oxide precursor according to claim 6 or 7 is mixed with a lithium source and sintered to obtain a ternary positive electrode material.

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