Preparation method of positive electrode material, positive electrode sheet and lithium ion battery

Abstract

The application discloses a preparation method of a positive electrode material, a positive electrode sheet and a lithium ion battery. The preparation method comprises the following steps: preparing a Li2ZrO3 precursor solution; adding NCM 811 powder into the Li2ZrO3 precursor solution to prepare a first slurry; performing first treatment on the first slurry to obtain a positive electrode powder; adding the positive electrode powder into a second solvent to prepare a positive electrode suspension; adding C 10 H 14 CuO4 into the positive electrode suspension to prepare a second slurry; and performing second treatment on the second slurry to obtain the positive electrode material. The rate performance of the positive electrode material prepared by the method is improved, the long cycle stability of the NCM 811 material is greatly improved, and the electrochemical performance of the NCM 811 material is comprehensively improved. Meanwhile, the preparation method of the positive electrode material is simple in steps, convenient to operate, and low in material cost.

Description

Technical Field

[0001] This invention relates to the field of battery manufacturing technology, and in particular to a method for preparing a positive electrode material, a positive electrode sheet, and a lithium-ion battery. Background Technology

[0002] Lithium-ion batteries have seen significant development in the new energy vehicle sector, characterized by high operating voltage, high energy density, long cycle life, and environmental friendliness. With the large-scale application of lithium-ion batteries in new energy vehicles and energy storage, higher demands are being placed on energy density, rate capability, safety, and price.

[0003] Energy density is one of the key performance indicators for rechargeable lithium-ion batteries and a significant driving force for the development of power batteries in my country. Currently, commercially available lithium-ion battery cathode materials mainly include lithium cobalt oxide (LiCoCO3), lithium iron phosphate (LiFePO4), nickel-cobalt-manganese (NCM) ternary materials, and nickel-cobalt-aluminum (NCA) ternary materials. With the market demand for high energy density, the development of high-nickel ternary materials is receiving increasing attention.

[0004] As the nickel content increases, the specific capacity of ternary materials continuously improves; however, at the same time, ternary materials also exhibit Li... + / Ni 2+ Problems such as mixing, side reactions between electrode materials and electrolyte during cycling, and deterioration of thermal stability cause high-nickel ternary materials to deteriorate in performance, reduce cycling stability, and reduce thermal stability during cycling. Summary of the Invention

[0005] (I) Purpose of the Invention

[0006] The purpose of this invention is to provide a method for preparing a positive electrode material, a positive electrode sheet, and a lithium-ion battery to solve the above-mentioned problems.

[0007] (II) Technical Solution

[0008] To address the aforementioned problems, a first aspect of the present invention provides a method for preparing a cathode material, comprising: preparing a Li₂ZrO₃ precursor solution; adding NCM 811 powder to the Li₂ZrO₃ precursor solution to obtain a first slurry; subjecting the first slurry to a first treatment to obtain cathode powder; adding the cathode powder to a second solvent to obtain a cathode suspension; and adding C₂ZrO₃ powder to the cathode suspension. 10 H 14 CuO4 was used to prepare a second slurry; the second slurry was then subjected to a second treatment to obtain the cathode material.

[0009] Further, the preparation of the Li2ZrO3 precursor solution includes: adding LiNO3 and Zr(NO3)4·5H2O to a first solvent in a molar ratio of 2:1 to obtain the Li2ZrO3 precursor solution.

[0010] Furthermore, the first solvent is an ethanol solution; the second solvent is an acetone solution.

[0011] Further, the step of adding LiNO3 and Zr(NO3)4·5H2O to the first solvent in a molar ratio of 2:1 to obtain the Li2ZrO3 precursor solution comprises: adding LiNO3 and Zr(NO3)4·5H2O to the first solvent in a molar ratio of 2:1; stirring at a first temperature until the LiNO3 and Zr(NO3)4·5H2O are fully dissolved to obtain the Li2ZrO3 precursor solution.

[0012] Furthermore, the first temperature is 40-60℃.

[0013] Furthermore, the first process includes: stirring, drying, grinding, and calcining.

[0014] Furthermore, the calcination includes: calcination at a temperature of 700-800℃ and a calcination time of 100-200 min in an oxygen atmosphere.

[0015] Furthermore, the step of adding the positive electrode powder to the second solvent to obtain the positive electrode suspension includes: adding the positive electrode powder to acetone solvent and refluxing it to fully disperse the positive electrode powder in the acetone solvent, thereby obtaining the positive electrode suspension.

[0016] Furthermore, the stirring includes stirring at a temperature of 40-60°C for 12-24 hours.

[0017] Furthermore, the second process includes a drying process.

[0018] Further, the second treatment of the second slurry to obtain the positive electrode material includes: condensing and refluxing the second slurry for 4-10 hours; centrifuging and drying the refluxed second slurry to obtain the positive electrode material.

[0019] According to another aspect of the present invention, a positive electrode sheet is provided, which is prepared by the preparation method described in any of the above technical solutions.

[0020] According to another aspect of the present invention, a positive electrode sheet is provided, which is manufactured by using the positive electrode material described in any of the above-described technical solutions.

[0021] According to another aspect of the present invention, a lithium-ion battery is provided, comprising the positive electrode sheet described in any of the above-described technical solutions.

[0022] (III) Beneficial Effects

[0023] The above-described technical solution of the present invention has the following beneficial technical effects:

[0024] The cathode material prepared by the method of this invention improves the rate performance and significantly enhances the long-cycle stability of NCM 811 cathode material, resulting in a comprehensive improvement in the electrochemical performance of NCM 811 material. Furthermore, the preparation method of this invention is simple, convenient to operate, and uses low-cost materials. Attached Figure Description

[0025] Figure 1 This is a flowchart of a method for preparing a cathode material according to an embodiment of the present invention.

[0026] Figure 2 These are XRD characterization comparison images of NCM 811 under different conditions.

[0027] Figure 3 These are SEM morphology comparison images of NCM 811 under different conditions.

[0028] Figure 4 This is a schematic diagram of a constant current charge-discharge cycle test of a positive electrode material at room temperature, provided by one embodiment of the present invention.

[0029] Figure 5 This is a schematic diagram of the rate performance of the cathode material according to one embodiment of the present invention.

[0030] Figure 6 A schematic diagram of constant current charge-discharge cycle test of positive electrode material at a high temperature of 50 degrees Celsius is provided in one embodiment of the present invention.

[0031] 2-Theta represents twice the diffraction angle, and the unit is degrees;

[0032] Intensity (Au) represents the diffraction intensity and has no unit.

[0033] The cycle number indicates the number of charge-discharge cycles of the battery. One discharge and one charge constitute one cycle.

[0034] Discharge capacity (mAh·g) -1 The value indicates the specific capacity of the battery discharge, and the unit is milliampere-hours per gram.

[0035] Coulombic efficiency (%) represents the coulombic efficiency of a battery, which is the ratio of the battery's discharge capacity to its charge capacity. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0037] The accompanying drawings illustrate a layer structure according to an embodiment of the present invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0038] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0039] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0040] The invention will now be described in more detail with reference to the accompanying drawings. In the various drawings, the same elements are indicated by similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale.

[0041] In one embodiment of the present invention, a method for preparing a positive electrode material is provided, comprising: preparing a Li2ZrO3 precursor solution; adding NCM 811 powder to the Li2ZrO3 precursor solution to obtain a first slurry; subjecting the first slurry to a first treatment to obtain positive electrode powder; adding the positive electrode powder to a second solvent to obtain a positive electrode suspension; and adding C to the positive electrode suspension. 10 H 14 CuO4 was used to prepare a second slurry; the second slurry was then subjected to a second treatment to obtain the cathode material.

[0042] The cathode material prepared by the method of the present invention exhibits improved rate performance and significantly enhanced long-cycle stability of NCM811 material, resulting in a comprehensive improvement in the electrochemical performance of NCM811 material. Furthermore, the preparation method of the cathode material of the present invention is simple, convenient to operate, and uses low-cost materials.

[0043] Figure 1 This is a flowchart of a method for preparing a cathode material according to an embodiment of the present invention.

[0044] like Figure 1 As shown, in one embodiment of the present invention, a method for preparing a positive electrode material is provided, comprising at least the following steps:

[0045] S100, Prepare Li2ZrO3 precursor solution.

[0046] S110. Add LiNO3 and Zr(NO3)4·5H2O to the first solvent in a molar ratio of 2:1 to form the Li2ZrO3 precursor solution.

[0047] S200: NCM 811 powder is added to the Li2ZrO3 precursor solution to prepare the first slurry.

[0048] S300. Perform a first treatment on the first slurry to obtain positive electrode powder.

[0049] S400. The positive electrode powder is added to the second solvent to prepare a positive electrode suspension.

[0050] S500, C is added to the positive electrode suspension. 10 H 14 CuO4 was used to prepare the second slurry.

[0051] S600, The second slurry is subjected to a second treatment to obtain the positive electrode material.

[0052] In an alternative embodiment, the mass of the NCM 811 powder added is 20-100 times the mass of the LiNO3.

[0053] In an optional embodiment, the preparation of the Li2ZrO3 precursor solution may include: adding LiNO3 and Zr(NO3)4·5H2O to a first solvent in a molar ratio of 2:1 to obtain the Li2ZrO3 precursor solution.

[0054] In an alternative embodiment, the C 10 H 14 The mass of CuO4 accounts for 0.1%-5% of the total mass of Li2ZrO3 in the NCM 811 powder and the Li2ZrO3 precursor solution.

[0055] In an alternative embodiment, the first solvent is an ethanol solution.

[0056] In an optional embodiment, the ethanol solution is anhydrous ethanol.

[0057] In an optional embodiment, the second solvent is an acetone solution.

[0058] In an optional embodiment, the acetone solution is of analytical grade.

[0059] In an optional embodiment, the step of adding LiNO3 and Zr(NO3)4·5H2O to a first solvent in a molar ratio of 2:1 to obtain the Li2ZrO3 precursor solution comprises: adding LiNO3 and Zr(NO3)4·5H2O to a first solvent in a molar ratio of 2:1; stirring at a first temperature until the LiNO3 and Zr(NO3)4·5H2O are fully dissolved to obtain the Li2ZrO3 precursor solution.

[0060] In an optional embodiment, the first temperature is 40-60°C.

[0061] In a preferred embodiment, the first temperature is 40°C.

[0062] In an optional embodiment, the first process may include: stirring, drying, grinding, and calcining.

[0063] By calcining the first slurry, the mixed LiNO3 and Zr(NO3)4·5H2O in the first slurry can react with the Li2ZrO3 precursor solution, and the LiNO3 and Zr(NO3)4·5H2O are calcined at a temperature of 750°C to generate Li2ZrO3.

[0064] In an optional embodiment, the calcination may include: calcining at a temperature of 700-800°C for 100-200 minutes in an oxygen atmosphere.

[0065] In an optional embodiment, adding the positive electrode powder to the second solvent to obtain a positive electrode suspension may include: adding the positive electrode powder to an acetone solvent and refluxing it to fully disperse the positive electrode powder in the acetone solvent, thereby obtaining a positive electrode suspension.

[0066] Reflux can allow copper acetylacetonate (C) to be released. 10 H 14 CuO4 is fully adsorbed onto the surface of NCM 811 particles through MO bonds under the action of acetone, achieving a coating effect.

[0067] In an optional embodiment, the stirring may include stirring at a temperature of 40-60°C for 12-24 hours.

[0068] In a preferred embodiment, the mixture is stirred at 40°C for 12 hours.

[0069] In an alternative embodiment, the second process may include a drying process.

[0070] In one optional embodiment, the second treatment of the second slurry to obtain the positive electrode material may include: condensing and refluxing the second slurry for 4-10 hours; centrifuging and drying the refluxed second slurry to obtain the positive electrode material.

[0071] Figure 2 These are XRD characterization comparison images of NCM 811 under different conditions.

[0072] Figure 2 From bottom to top, the layers are: uncoated NCM811, coated with 1% Li2ZrO3, and coated with 0.8% C. 10 H 14 CuO4 NCM811, coated with 3% Li2ZrO3 and 0.8% C 10 H 14 CuO4 NCM811 and coated with 5% Li2ZrO3 and 0.8% C 10 H 14 XRD characterization of CuO4-containing NCM811 (the coating did not change the layered structure of NCM811; the percentage represents the mass percentage).

[0073] like Figure 2 As shown, the presence of cracks (006 / 102) and (108 / 110) indicates that the NCM811 material maintains a layered structure. However, as the coating amount increases, the ratios of (003) and (104) decrease sequentially, indicating that the Li / Ni mixing degree intensifies. Furthermore, when the Li2ZrO3 coating amount is 5%, C 10 H 14 When the CuO4 coating content is 0.8%, Li / Ni mixing is severe.

[0074] Figure 3 These are SEM morphology comparison images of NCM 811 under different conditions.

[0075] Figure 3 Figure (a) shows the SEM analysis of the uncoated NCM811 secondary particle spheres.

[0076] Figure 3 Figure (b) shows the SEM analysis of the surface of the uncoated NCM811 secondary particle spheres.

[0077] Figure 3 Figure (c) shows the coating of 3% Li₂ZrO₃ and 0.8% C. 10 H 14 SEM image of secondary particles of CuO4 NCM811.

[0078] Figure 3 Figure d shows the coating of 3% Li₂ZrO₃ and 0.8% C. 10 H 14 SEM image of the surface of secondary particles of CuO4 NCM811.

[0079] Figure 3 Figures (e) and (j) show the coating amounts of 3% Li₂ZrO₃ and 0.8% C, respectively. 10 H 14 Mapping diagram of CuO4 NCM811.

[0080] Figure 3 Figure (e) shows coatings with 3% Li₂ZrO₃ and 0.8% C. 10 H 14 Mn elemental distribution diagram of CuO4 NCM811.

[0081] Figure 3 Figure (f) shows the coating amounts of 3% Li₂ZrO₃ and 0.8% C. 10 H 14 Cu elemental distribution diagram of NCM811 CuO4.

[0082] Figure 3 The middle (g) figure shows coatings with 3% Li₂ZrO₃ and 0.8% C. 10 H 14 Ni element distribution diagram of CuO4 NCM811.

[0083] Figure 3 The middle (h) figure shows the coating of 3% Li2ZrO3 and 0.8% C. 10 H 14 O element distribution diagram of CuO4 NCM811.

[0084] Figure 3 Figure (i) shows coatings with 3% Li₂ZrO₃ and 0.8% C. 10 H 14 Zr elemental distribution diagram of CuO4 NCM811.

[0085] Figure 3 Figure (j) shows coatings with 3% Li₂ZrO₃ and 0.8% C. 10 H 14 Co elemental distribution diagram of CuO4 NCM811.

[0086] Figures (a) and (c) show that the secondary particles of uncoated and coated NCM811 materials are regular spherical. Comparing Figures (b) and (d), we can see that the surface of the coated NCM811 secondary particles is rough and blurred, indicating that the surface of the secondary particles is coated with a layer of material. The mapping diagram below shows that the elements are evenly distributed on the particle surface. Figure (i) shows that the Zr element is evenly distributed on the surface, indicating that Li2ZrO3 has been coated on the surface of the secondary particles.

[0087] Figure 4 This is a schematic diagram of a constant current charge-discharge cycle test of a positive electrode material at room temperature, provided by one embodiment of the present invention.

[0088] like Figure 4 As shown, through long-term cycling comparison at room temperature, it can be found that the discharge specific capacity of the uncoated NCM 811 cathode material is slightly higher than that of the coated NCM 811 cathode material before the first 100 cycles. This is mainly because the coating layer on the surface of the NCM 811 material hinders the transport of lithium ions, thus making its discharge specific capacity lower than that of the uncoated NCM 811 material. However, as the cycling progresses, after 100 cycles, the discharge specific capacity of the coated NCM 811 cathode material is significantly higher than that of the uncoated NCM 811 material, and after 200 cycles, the uncoated NCM 811 material shows a sharp decline. This is mainly because, as cycling progresses, severe side reactions occur between the uncoated NCM 811 cathode material surface and the electrolyte. These side reactions damage the material structure and produce a series of behaviors that are detrimental to lithium-ion transport, such as rock salt phase. The presence of the coating layer can prevent the NCM 811 cathode material from reacting with the electrolyte. Furthermore, as cycling progresses, the NCM 811 cathode material is fully activated, enabling Li ions to be stably inserted and extracted, thus allowing for continuous and stable charge-discharge cycling.

[0089] Figure 5 This is a schematic diagram of the rate performance of the cathode material according to one embodiment of the present invention.

[0090] like Figure 5As shown, a rate comparison reveals that there is no significant difference between the uncoated and coated NCM 811 materials before 0.2C. However, after 0.2C, the coated NCM 811 material exhibits a significantly higher discharge specific capacity at different rates than the uncoated NCM 811 material. Furthermore, at a high discharge rate of 10C, the coated NCM 811 material also maintains a discharge specific capacity of approximately 60 mAh / g⁻¹, indicating that the coated NCM 811 material possesses superior rate performance. This is primarily because Li₂ZrO₃ is a good conductor of lithium, and coating the surface of the NCM 811 cathode material facilitates rapid lithium-ion transport and prevents side reactions between the material and the electrolyte. In contrast, the uncoated NCM 811 material undergoes side reactions with the electrolyte during cycling and, at high rates, exhibits cracking and other structural damage that negatively impacts lithium-ion transport.

[0091] Figure 6 A schematic diagram of constant current charge-discharge cycle test of positive electrode material at a high temperature of 50 degrees Celsius is provided in one embodiment of the present invention.

[0092] like Figure 6 As shown, long-cycle testing at 50°C revealed that the coated material exhibited a significantly higher discharge specific capacity than the uncoated NCM 811 material at 50°C. Furthermore, its coulombic efficiency during recycle was also significantly higher than that of the uncoated NCM 811 cathode material. This indicates that during cycling, lithium ions from the uncoated NCM 811 material cannot all return to the cathode material, resulting in a decrease in discharge specific capacity and thus reducing cycle life.

[0093] In another embodiment of the present invention, a positive electrode material is provided, which is prepared by any of the preparation methods described in the above technical solutions.

[0094] In another embodiment of the present invention, a positive electrode sheet is provided, which is manufactured by using the positive electrode material described in any of the above technical solutions.

[0095] In another embodiment of the present invention, a lithium-ion battery is provided, which may include the positive electrode sheet described in any of the above technical solutions.

[0096] This invention provides a method for preparing a positive electrode material, a positive electrode sheet, and a lithium-ion battery. The method for preparing the positive electrode material includes: preparing a Li₂ZrO₃ precursor solution; adding NCM 811 powder to the Li₂ZrO₃ precursor solution to obtain a first slurry; subjecting the first slurry to a first treatment to obtain positive electrode powder; adding the positive electrode powder to a second solvent to obtain a positive electrode suspension; and adding C to the positive electrode suspension. 10 H14 CuO4 is used to prepare a second slurry; the second slurry undergoes a second treatment to obtain the cathode material. The cathode material prepared by the method of the present invention exhibits improved rate performance and significantly enhanced long-cycle stability of NCM811 material, resulting in a comprehensive improvement in the electrochemical performance of NCM811 material. Furthermore, the preparation method of the cathode material of the present invention is simple, convenient to operate, and uses low-cost materials.

[0097] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A method for preparing a positive electrode material, characterized in that, include: Preparation of Li₂ZrO₃ precursor solution; The first slurry was prepared by adding NCM 811 powder to the Li2ZrO3 precursor solution. The first slurry is subjected to a first treatment to obtain positive electrode powder; The positive electrode powder is added to the second solvent to prepare a positive electrode suspension; C was added to the positive electrode suspension 10 H 14 CuO4 was used to prepare the second slurry; The second slurry is subjected to a second treatment to obtain the positive electrode material; The preparation of the Li2ZrO3 precursor solution includes: adding LiNO3 and Zr(NO3)4·5H2O to a first solvent in a molar ratio of 2:1 to obtain the Li2ZrO3 precursor solution; The first solvent is an ethanol solution; the second solvent is an acetone solution; The first process includes: stirring, drying, grinding, and calcining; The calcination includes: calcination at a temperature of 700-800℃ and a calcination time of 100-200 min in an oxygen atmosphere; The second treatment of the second slurry to obtain the positive electrode material includes: The second slurry is refluxed for 4-10 hours. The second slurry after reflux is centrifuged and then dried to obtain the positive electrode material.

2. The method for preparing the cathode material according to claim 1, characterized in that, The step of adding LiNO3 and Zr(NO3)4·5H2O to the first solvent in a molar ratio of 2:1 to obtain the Li2ZrO3 precursor solution includes: LiNO3 and Zr(NO3)4·5H2O were added to the first solvent in a molar ratio of 2:1; The mixture is stirred at a first temperature until the LiNO3 and Zr(NO3)4·5H2O are fully dissolved to obtain the Li2ZrO3 precursor solution.

3. The method for preparing the cathode material according to claim 2, characterized in that, The first temperature is 40-60℃.

4. The method for preparing the cathode material according to claim 1, characterized in that, The step of adding the positive electrode powder to the second solvent to prepare the positive electrode suspension includes: The positive electrode powder is added to acetone solvent and refluxed to fully disperse the positive electrode powder in the acetone solvent, thus obtaining a positive electrode suspension.

5. The method for preparing the cathode material according to claim 1, characterized in that, The stirring includes: Stir at 40-60℃ for 12-24 hours.

6. The method for preparing the cathode material according to claim 1, characterized in that, The second process includes a drying process.

7. A positive electrode material, characterized in that, It is prepared by the preparation method according to any one of claims 1-6.

8. A lithium-ion battery, characterized in that, Includes the cathode material as described in claim 7.

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