A molybdenum-fluorine double-doped high-nickel cobalt-free positive electrode material, a preparation method and application thereof

Abstract

The application discloses a molybdenum-fluorine double-doped high-nickel cobalt-free positive electrode material and a preparation method and application thereof. a Ni x Mn y Mo 1‑x‑y F z O b , wherein 1<=a<=1.2, 1.9<=b<=2.1, 0.75<=x<=0.8, 0.02<=y<=0.2, 0.01<=z<=0.03; the molybdenum-fluorine double-doped high-nickel cobalt-free positive electrode material has a particle size of 2-3 mu m, and has an R-3m layered structure inside the material. When the molybdenum-fluorine double-doped high-nickel cobalt-free positive electrode material is used in a lithium ion secondary battery, the lithium ion secondary battery has excellent electrochemical performance, is environment-friendly, and can greatly control the cost of the lithium ion secondary battery. The molybdenum-fluorine double-doped high-nickel cobalt-free positive electrode material has a simple preparation process, good reproducibility and is suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention belongs to the field of new energy storage technology, and relates to a lithium-ion battery cathode material, its preparation method and application, and in particular to a high-nickel cobalt-free cathode material doped with molybdenum and fluorine, its preparation method and application. Background Technology

[0002] Lithium-ion batteries, with their advantages of high discharge specific capacity and long cycle life, have been widely used in consumer electronics, electric vehicles, and energy storage. However, with rapid socio-economic development, people have placed higher demands on power batteries in terms of energy density, safety, and environmental friendliness. As a key component of lithium-ion batteries, cathode materials have always been a research focus. Among the currently commercialized layered cathode materials, lithium cobalt oxide (LiCoO2) has become one of the earliest materials to achieve full commercialization due to its simple synthesis process and excellent cycle performance. However, its capacity density is relatively low and can no longer meet current needs. In contrast, high-nickel cobalt-manganese ternary materials (such as NCM811) have become the most promising cathode materials in the electric vehicle field due to their higher energy density. However, due to the scarcity and high price of global cobalt resources, its radioactivity and potential environmental pollution, as well as its relatively low safety, its widespread application still faces many challenges.

[0003] This invention addresses the problems existing in current lithium-ion battery cathode materials by developing a novel material system that combines high capacity and excellent cycle performance. To improve the cycle stability and rate performance of the high-nickel cobalt-free material and reduce the degree of lithium-nickel mixing, a dual doping strategy of molybdenum and fluorine anions and cations is adopted, thereby further reducing the production cost of the high-nickel cobalt-free cathode material and significantly improving its lithium storage performance. Summary of the Invention

[0004] The purpose of this invention is to address the problems existing in current lithium-ion battery cathode materials by developing a novel high-nickel cobalt-free material system that combines high capacity and excellent cycle performance. To improve the cycle stability and rate performance of the high-nickel cobalt-free cathode material, reduce lithium-nickel mixing, and lower the production cost, a dual-doping strategy using molybdenum and fluorine anions and cations is employed. This further reduces the production cost of the high-nickel cathode material and significantly improves its lithium storage performance.

[0005] The molybdenum-fluorine dual-doped high-nickel cobalt-free cathode material Li of the present invention a Ni x Mn y Mo 1-x-y F z O bWhere 1≤a≤1.2, 1.9≤b≤2.1, 0.75≤x≤0.8, 0.02≤y≤0.2, and 0.01≤z≤0.03, the dual doping of Mo and F can alleviate the irreversible phase transition process that occurs in high-nickel cobalt-free cathode materials under high cutoff voltage. This not only improves the initial coulombic efficiency (96.9%), but also improves its cycle life (after 100 cycles, a discharge specific capacity of 116.2 mAh / g and a capacity retention of 99.08% were achieved).

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A high-nickel, cobalt-free cathode material doped with molybdenum and fluorine, characterized in that Li a Ni x Mn y Mo 1-x-y F z O b Where 1≤a≤1.2, 1.9≤b≤2.1, 0.75≤x≤0.8, 0.02≤y≤0.2, and 0.01≤z≤0.03.

[0008] To achieve the above objectives, another technical solution adopted by the present invention is:

[0009] A method for preparing a molybdenum-fluorine dual-doped high-nickel cobalt-free cathode material includes the following steps:

[0010] Step 1: Add nickel salt and manganese salt to deionized water at a molar mass ratio of (0.801-0.899):(0.101-0.199) and stir continuously to obtain solution A;

[0011] Step 2: Mix ammonia water (ammonia content 25-28%) and deionized water at a volume ratio of (0.1-0.6):1 and stir continuously for 60 minutes to obtain an ammonia solution;

[0012] Step 3: Slowly add solution A to the ammonia solution at a rate of 0.1–0.8 mL / min using a peristaltic pump, while continuously stirring at 500–1000 rpm under nitrogen protection; simultaneously, add a 1–5 mol / L solution at a rate of 0.3–1 mL / min. -1 A sodium hydroxide solution was prepared, ensuring the pH of the mixed solution was between 10.2 and 11.6, and the temperature of the entire system was between 40 and 80°C. After continuous stirring for 24–48 hours, the mixture was allowed to stand at room temperature for 4–12 hours. Following centrifugation, washing, and drying, the precursor Ni for nickel-manganese binary materials was obtained. x Mn 1-x (OH)₂, where 0.79 ≤ x ≤ 0.99;

[0013] Step 4: Add the precursor Ni x Mn 1-x (OH)₂: molybdenum oxide: ammonium fluoride: lithium salt were mixed and ground in a molar ratio of 1:(0.05~0.09):(0.03~0.05):(1.01~1.08) for 30~60 min. The mixture was then heated at 850~1000℃ in an O₂ atmosphere at a heating rate of 1.0~3.0℃ / min for 10~20 h, and then naturally cooled to room temperature to obtain a high-nickel, cobalt-free cathode material Li₂ with molybdenum-fluorine dual doping and surface Mo enrichment. a Ni x Mn y Mo 1-x-y F z O b Where 1≤a≤1.2, 1.9≤b≤2.1, 0.75≤x≤0.8, 0.02≤y≤0.2, and 0.01≤z≤0.03.

[0014] Further preferred, in step (1), the nickel salt is any one of nickel sulfate, nickel chloride, and nickel nitrate.

[0015] Further preferred, in step (1), the nickel salt is any one of manganese sulfate, manganese chloride, and manganese nitrate.

[0016] Further preferred, in step (4), the lithium salt is any one of lithium hydroxide, lithium carbonate, and lithium acetate.

[0017] An application of a molybdenum-fluorine dual-doped high-nickel, cobalt-free cathode material, characterized in its use as a cathode material for lithium-ion batteries. Specifically, its application in CR2032 coin-type lithium-ion batteries includes the following steps:

[0018] (a) Mix the high-nickel cobalt-free composite material: Ketjen black: polyvinylidene fluoride = (6-8):(3-1):1 by mass ratio, stir evenly, and obtain a solid mixture;

[0019] (b) The solid mixture obtained in step (a) is mixed with N-methylpyrrolidone at a mass ratio of 1:(3-4), and stirred evenly to obtain a slurry;

[0020] (c) The slurry obtained in step (b) is coated onto copper foil, and after drying and rolling, a lithium-ion battery electrode sheet with a thickness of 13 to 22 μm is obtained.

[0021] (d) The lithium-ion battery electrode sheet obtained in step (c) is used as the negative electrode sheet, a microporous polypropylene membrane is used as the separator, and a mixture of equal volumes of dimethyl carbonate and dipropyl carbonate in 1 mol / L LiPF6 is used as the electrolyte. The mixture is assembled into a CR2032 coin cell lithium-ion battery in an argon-filled glove box.

[0022] The advantages and beneficial effects of this invention are as follows: This invention combines the inherent advantages of high-nickel cobalt-free cathode materials, such as high capacity, good safety, and low cost, and further optimizes the lithium-ion transport channel structure by employing Mo and F dual doping, reducing lithium-nickel mixing and improving the lithium-ion diffusion rate, thereby improving rate performance. Therefore, when the molybdenum-fluorine dual-doped high-nickel cobalt-free cathode material obtained by combining the above effects is used in lithium-ion batteries, it can greatly improve the cycle performance, capacity, and thermal stability of lithium-ion batteries. Attached Figure Description

[0023] Figure 1 The molybdenum-fluorine dual-doped high-nickel cobalt-free cathode material Ni prepared in Example 1 of this invention 0.8 Mn 0.2 Scanning electron microscope (SEM) image of (OH)2 precursor.

[0024] Figure 2 The molybdenum-fluorine dual-doped high-nickel cobalt-free cathode material LiNi prepared in Example 1 of this invention. 0.8 Mn 0.2 Scanning electron microscope (SEM) image of O2.

[0025] Figure 3 The molybdenum-fluorine dual-doped high-nickel cobalt-free cathode material LiNi prepared in Example 1 of this invention. 0.75 Mn 0.2 Mo 0.05 F 0.03 O 1.97 Scanning electron microscope (SEM) image.

[0026] Figure 4 This refers to the molybdenum-fluorine dual-doped high-nickel cobalt-free cathode material LiNi prepared in Example 1 of this invention. 0.75 Mn 0.2 Mo 0.05 F 0.03 O 1.97 Scanning transmission electron microscopy (STEM) image.

[0027] Figure 5 The molybdenum-fluorine dual-doped high-nickel cobalt-free cathode material LiNi prepared in Example 1 of this invention is... 0.8 Mn 0.2 O2 (abbreviated as NM) and LiNi doped with Mo and F 0.75 Mn 0.2 Mo 0.05 F 0.03 O 1.97 X-ray diffraction (XRD) pattern of (abbreviated as MF-NM).

[0028] Figure 6The high-nickel, cobalt-free cathode material LiNi prepared in Example 1 of this invention is 0.8 Mn 0.2 O2 (abbreviated as NM) and LiNi doped with Mo and F 0.75 Mn 0.2 Mo 0.05 F 0.03 O 1.97 (abbreviated as MF-NM) is used as a cathode material for lithium-ion batteries at 3.0C (1C = 200mAh g). -1 Performance graph after 100 cycles at a given speed.

[0029] Figure 7 The high-nickel, cobalt-free cathode material LiNi prepared in Example 1 of this invention is 0.8 Mn 0.2 O2 (abbreviated as NM) and LiNi doped with Mo and F 0.75 Mn 0.2 Mo 0.05 F 0.03 O 1.97 (abbreviated as MF-NM) is used as a cathode material for lithium-ion batteries at 3.0C (1C = 200mAh g). -1 Coulomb efficiency diagram for each of 100 cycles at a given rate. Detailed Implementation

[0030] To enable those skilled in the art to more fully understand the present invention, preferred embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Features in the embodiments of the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and examples.

[0031] Example 1

[0032] 1. A method for preparing a high-nickel, cobalt-free cathode material doped with molybdenum and fluorine, specifically including the following steps:

[0033] (1) Weigh 12.45g of nickel sulfate and 0.25g of manganese sulfate respectively and dissolve them in 25mL of deionized water. Stir until fully dissolved to obtain solution A.

[0034] (2) Measure 5.0 mL of ammonia water (ammonia content is 25-28%) and 75.0 mL of deionized water respectively to prepare an ammonia solution, stir continuously and heat to 60°C.

[0035] (3) Solution A was slowly added dropwise to the ammonia solution at a rate of 0.3 mL / min, and stirred continuously at a speed of 500–1000 rpm under nitrogen protection; simultaneously, a 2.0 mol L solution was added dropwise at a rate of 0.3 mL / min. -1 A NaOH solution was prepared, and the temperature of the entire system was maintained at 60℃, with the pH of the mixed solution at 11.0. After stirring continuously for 24 hours, the mixture was allowed to stand at room temperature for 10 hours. Then, after centrifugation, washing, and drying, the precursor Ni for nickel-manganese binary materials was obtained. 0.8 Mn 0.2 (OH)2;

[0036] (4) Add 0.51g of precursor Ni 0.8 Mn 0.2 (OH)₂, 0.12 g molybdenum oxide, 0.06 g ammonium fluoride, and 0.24 g lithium hydroxide were mixed and ground for 60 min. The mixture was then heated at 1000 °C in an O₂ atmosphere at a heating rate of 2.5 °C / min for 16 h, followed by natural cooling to room temperature to obtain a molybdenum-fluorine dual-doped high-nickel cobalt-free cathode material, LiNi. 0.75 Mn 0.2 Mo 0.05 F 0.03 O 1.97 (abbreviated as MF-NM); simultaneously, 0.51g of precursor Ni 0.8 Mn 0.2 (OH)₂ and 0.24 g of lithium hydroxide were mixed and ground for 60 min. The mixture was then kept at 1000 °C for 16 h in an O₂ atmosphere with a heating rate of 2.5 °C / min, followed by natural cooling to room temperature to obtain the high-nickel, cobalt-free cathode material LiNi. 0.8 Mn 0.2 O2 (abbreviated as NM).

[0037] 2. A method for applying a molybdenum-fluorine dual-doped high-nickel, cobalt-free cathode material to a CR2032 coin cell lithium-ion battery, comprising the following steps:

[0038] (a) Molybdenum-fluorine dual-doped high-nickel cobalt-free cathode material, polyvinylidene fluoride, and Ketjen black were mixed evenly at a mass ratio of 8:1:1 to obtain a solid mixture;

[0039] (b) The solid mixture obtained in step (a) is mixed with N-methylpyrrolidone at a mass ratio of 25:75 and stirred evenly to obtain a slurry;

[0040] (c) The slurry obtained in step (b) is coated onto aluminum foil, and after drying and rolling, a lithium-ion battery electrode sheet with a thickness of 10 to 24 μm is obtained.

[0041] (d) The lithium-ion battery electrode sheet obtained in step (c) is used as the negative electrode sheet, the lithium sheet is used as the positive electrode sheet, a microporous polypropylene membrane is used as the separator, and 1 mol / L LiPF6 and solvent are used as the electrolyte. The CR2032 button lithium-ion battery is assembled in a glove box filled with argon gas.

[0042] (e) The lithium-ion battery assembled in step (d) is tested at a voltage of 2.8 to 4.3V and a test temperature of 25°C.

[0043] Example 2

[0044] 1. A method for preparing a high-nickel, cobalt-free cathode material doped with molybdenum and fluorine, specifically including the following steps:

[0045] (1) Weigh 11.0g of nickel chloride and 0.36g of manganese chloride respectively and dissolve them in 25mL of deionized water. Stir until fully dissolved to obtain solution A.

[0046] (2) Measure 9.4 mL of ammonia water (ammonia content is 25-28%) and 90.6 mL of deionized water respectively to prepare 100 mL of ammonia water solution, stir continuously and heat to 70℃.

[0047] (3) Solution A was slowly added dropwise to the ammonia solution at a rate of 0.1 mL / min, and stirred continuously at a speed of 500–1000 rpm under nitrogen protection; simultaneously, a 4.0 mol / L solution was added dropwise at a rate of 0.3 mL / min. -1 A NaOH solution was prepared, and the temperature of the entire system was maintained at 60℃, with the pH of the mixed solution at 11.6. After stirring continuously for 24 hours, the mixture was allowed to stand at room temperature for 10 hours. Then, after centrifugation, washing, and drying, the precursor Ni for nickel-manganese binary materials was obtained. 0.85 Mn 0.15 (OH)2;

[0048] (4) Add 0.53g of precursor Ni 0.85 Mn 0.15 (OH)₂, 0.19 g molybdenum oxide, 0.03 g ammonium fluoride, and 0.35 g lithium hydroxide were mixed and ground for 60 min. The mixture was then heated at 950 °C in an O₂ atmosphere at a heating rate of 2.5 °C / min for 16 h, followed by natural cooling to room temperature to obtain a high-nickel, cobalt-free cathode material, Li₂, which is doped with molybdenum and fluorine. 1.2 Ni 0.80 Mn 0.19 Mo 0.01 F 0.01 O2.

[0049] 2. A method for applying a molybdenum-fluorine dual-doped high-nickel, cobalt-free cathode material to a CR2032 coin cell lithium-ion battery, comprising the following steps:

[0050] (a) Molybdenum-fluorine dual-doped high-nickel cobalt-free cathode material, polyvinylidene fluoride, and Ketjen black were mixed evenly at a mass ratio of 6:2:2 to obtain a solid mixture;

[0051] (b) The solid mixture obtained in step (a) is mixed with N-methylpyrrolidone at a mass ratio of 25:75 and stirred evenly to obtain a slurry;

[0052] (c) The slurry obtained in step (b) is coated onto aluminum foil, and after drying and rolling, a lithium-ion battery electrode sheet with a thickness of 10 to 24 μm is obtained.

[0053] (d) The lithium-ion battery electrode sheet obtained in step (c) is used as the negative electrode sheet, the lithium sheet is used as the positive electrode sheet, a microporous polypropylene membrane is used as the separator, and 1 mol / L LiPF6 and solvent are used as the electrolyte. The CR2032 button lithium-ion battery is assembled in a glove box filled with argon gas.

[0054] (e) The lithium-ion battery assembled in step (d) is tested at a voltage of 2.8 to 4.3V and a test temperature of 25°C.

[0055] Example 3

[0056] 1. A method for preparing a high-nickel, cobalt-free cathode material doped with molybdenum and fluorine, specifically including the following steps:

[0057] (1) Weigh 11.17g of nickel nitrate and 0.37g of manganese nitrate respectively and dissolve them in 25mL of deionized water. Stir until fully dissolved to obtain solution A.

[0058] (2) Measure 34.5 mL of ammonia water (ammonia content is 25-28%) and 65.5 mL of deionized water respectively, mix them to prepare 100 mL of ammonia water solution, stir continuously and heat to 80℃.

[0059] (3) Solution A is slowly added dropwise to the ammonia solution at a rate of 0.1 mL / min, and stirred continuously at a speed of 500–1000 rpm under nitrogen protection; simultaneously, a 4 mol L solution is added dropwise at a rate of 0.2 mL / min. -1 A NaOH solution was prepared, and the temperature of the entire system was maintained at 60℃, with the pH of the mixed solution at 10.2. After stirring continuously for 24 hours, the mixture was allowed to stand at room temperature for 10 hours. Then, after centrifugation, washing, and drying, the precursor Ni for nickel-manganese binary materials was obtained. 0.83 Mn 0.17 (OH)2;

[0060] (4) Add 0.59g of precursor Ni 0.8 Mn 0.2(OH)₂, 0.22 g molybdenum oxide, 0.04 g ammonium fluoride, and 0.28 g lithium hydroxide were mixed and ground for 60 min. The mixture was then heated at 850 °C in an O₂ atmosphere at a heating rate of 2.5 °C / min for 16 h, followed by natural cooling to room temperature to obtain a high-nickel, cobalt-free cathode material, Li₂, which is doped with molybdenum and fluorine. 1.1 Ni 0.81 Mn 0.15 Mo 0.04 F 0.02 O 1.95 .

[0061] 2. A method for applying a molybdenum-fluorine dual-doped high-nickel, cobalt-free cathode material to a CR2032 coin cell lithium-ion battery, comprising the following steps:

[0062] (a) Molybdenum-fluorine dual-doped high-nickel cobalt-free cathode material, polyvinylidene fluoride, and Ketjen black were mixed evenly at a mass ratio of 95:2.5:2.5 to obtain a solid mixture;

[0063] (b) The solid mixture obtained in step (a) is mixed with N-methylpyrrolidone at a mass ratio of 25:75 and stirred evenly to obtain a slurry;

[0064] (c) The slurry obtained in step (b) is coated onto aluminum foil, and after drying and rolling, a lithium-ion battery electrode sheet with a thickness of 10 to 24 μm is obtained.

[0065] (d) The lithium-ion battery electrode sheet obtained in step (c) is used as the negative electrode sheet, the lithium sheet is used as the positive electrode sheet, a microporous polypropylene membrane is used as the separator, and 1 mol / L LiPF6 and solvent are used as the electrolyte. The CR2032 button lithium-ion battery is assembled in a glove box filled with argon gas.

[0066] (e) The lithium-ion battery assembled in step (d) is tested at a voltage of 2.8 to 4.3V and a test temperature of 25°C.

[0067] Example 4

[0068] 1. A method for preparing a high-nickel, cobalt-free cathode material doped with molybdenum and fluorine, specifically including the following steps:

[0069] (1) Weigh 10.56g of nickel sulfate and 0.16g of manganese sulfate respectively and dissolve them in 25mL of deionized water. Stir until fully dissolved to obtain solution A.

[0070] (2) Measure 17.5 mL of ammonia water (ammonia content of 25-28%) and 82.5 mL of deionized water respectively, mix them to form 100 mL of ammonia water solution, stir continuously and heat to 60°C.

[0071] (3) Solution A is slowly added dropwise to the ammonia solution at a rate of 0.1 mL / min, and stirred continuously at a speed of 500–1000 rpm under nitrogen protection; simultaneously, a 4 mol L solution is added dropwise at a rate of 0.2 mL / min. -1 A NaOH solution was prepared, and the temperature of the entire system was maintained at 80℃, with the pH of the mixed solution at 11.5. After stirring continuously for 24 hours, the mixture was allowed to stand at room temperature for 10 hours. Then, after centrifugation, washing, and drying, the precursor Ni for nickel-manganese binary materials was obtained. 0.9 Mn 0.1 (OH)2;

[0072] (4) Add 0.53g of precursor Ni 0.9 Mn 0.1 (OH)₂, 0.39 g molybdenum oxide, 0.09 g ammonium fluoride, and 0.26 g lithium carbonate were mixed and ground for 60 min. The mixture was then heated at 1000 °C in an O₂ atmosphere at a heating rate of 2.5 °C / min for 20 h, followed by natural cooling to room temperature to obtain a high-nickel, cobalt-free cathode material, Li₂, doped with molybdenum and fluorine. 1.05 Ni 0.85 Mn 0.1 Mo 0.05 F 0.01 O 2.1 .

[0073] 2. A method for applying a molybdenum-fluorine dual-doped high-nickel, cobalt-free cathode material to a CR2032 coin cell lithium-ion battery, comprising the following steps:

[0074] (a) Molybdenum-fluorine dual-doped high-nickel cobalt-free cathode material, polyvinylidene fluoride, and Ketjen black were mixed evenly in a mass ratio of 92.5:3.75:3.75 to obtain a solid mixture;

[0075] (b) The solid mixture obtained in step (a) is mixed with N-methylpyrrolidone at a mass ratio of 25:75 and stirred evenly to obtain a slurry;

[0076] (c) The slurry obtained in step (b) is coated onto aluminum foil, and after drying and rolling, a lithium-ion battery electrode sheet with a thickness of 10 to 24 μm is obtained.

[0077] (d) The lithium-ion battery electrode sheet obtained in step (c) is used as the negative electrode sheet, the lithium sheet is used as the positive electrode sheet, a microporous polypropylene membrane is used as the separator, and 1 mol / L LiPF6 and solvent are used as the electrolyte. The CR2032 button lithium-ion battery is assembled in a glove box filled with argon gas.

[0078] (e) The lithium-ion battery assembled in step (d) is tested at a voltage of 2.8 to 4.3V and a test temperature of 25°C.

[0079] Figure 1 Ni prepared in Example 1 0.8 Mn 0.2 Scanning electron microscope (SEM) images of the (OH)2 high-nickel cobalt-free cathode material precursor show that the secondary particles of the precursor are uniformly and regularly spherical with a diameter of about 3 to 5 μm.

[0080] Figure 2 The high-nickel, cobalt-free cathode material LiNi prepared in Example 1 0.8 Mn 0.2 Scanning electron microscopy (SEM) images of O2 show clear morphologies of single-crystal particles with a diameter of approximately 2–3 μm. The calcined material exhibits partial breakage and aggregation.

[0081] Figure 3 The molybdenum-fluorine dual-doped high-nickel cobalt-free cathode material LiNi prepared in Example 1 0.75 Mn 0.2 Mo 0.05 F 0.03 O 1.97 The scanning electron microscope (SEM) images clearly show the morphology of the single-crystal particles, with a particle size of approximately 2–3 μm. The doped material particles are uniform and show no aggregation.

[0082] Figure 4 The molybdenum-fluorine dual-doped high-nickel cobalt-free cathode material LiNi prepared in Example 1 0.75 Mn 0.2 Mo 0.05 F 0.03 O 1.97 The STEM image shows a complete and uniform R-3m layered structure inside the material.

[0083] Figure 5 The high-nickel, cobalt-free cathode material LiNi prepared in Example 1 0.8 Mn 0.2 O2 (abbreviated as NM) and LiNi 0.75 Mn 0.2 Mo 0.05 F 0.03 O 1.97 The XRD patterns of (abbreviated as MF-NM) clearly show that both materials exhibit a distinct LiNiO2R-3m space lattice group, indicating that both materials have complete crystal structures. Furthermore, the peak of MF-NM shifts towards a smaller angle, suggesting that the dual doping of Mo and F is beneficial for increasing the lattice spacing, thereby facilitating lithium-ion transport.

[0084] Figure 6 The high-nickel, cobalt-free cathode material LiNi prepared in Example 1 0.8 Mn0.2 O2 (abbreviated as NM) and LiNi 0.75 Mn 0.2 Mo 0.05 F 0.03 O 1.97 (abbreviated as MF-NM) is used as a positive electrode material for lithium-ion batteries at 3.0C (1C = 200mAh g). -1 The cycling performance graph below shows that MF-NM maintained a discharge capacity of 116.2 mAh / g after 100 cycles, while NM's discharge capacity was only 39.6 mAh / g after 100 cycles.

[0085] Figure 7 The high-nickel, cobalt-free cathode material LiNi prepared in Example 1 0.8 Mn 0.2 O2 (abbreviated as NM) and LiNi 0.75 Mn 0.2 Mo 0.05 F 0.03 O 1.97 (abbreviated as MF-NM) is used as a positive electrode material for lithium-ion batteries at 3.0C (1C = 200mAh g). -1 Coulomb efficiency diagram for each of the next 100 cycles. The coulomb efficiency of NM is unstable and below 90%, while the coulomb efficiency of MF-NM is stable above 95%.

[0086] The molybdenum-fluorine dual-doped high-nickel cobalt-free cathode materials LiNi prepared in Examples 1-4 0.75 Mn 0.2 Mo 0.05 F 0.03 O 1.97 The performance results of the lithium-ion battery are shown in Table 1.

[0087] Table 1 shows the lithium-ion batteries of Examples 1, 2, 3, and 4 at 3.0C (1C = 200mAh g). -1 The capacity obtained from the 2nd and 100th cycles of charge-discharge testing.

[0088] Table 1

[0089]

[0090] As can be seen from Table 1, the high-nickel, cobalt-free cathode material LiNi with molybdenum and fluorine dual doping of the present invention is effective. 0.75 Mn 0.2 Mo 0.05 F 0.03 O 1.97When applied to lithium-ion batteries, the charging capacity can still be maintained above 110mAh / g after 100 cycles at a high rate of 3.0C, demonstrating excellent cycle performance, which is superior to currently commercialized high-nickel cathode materials such as NCM811 and NCA622.

[0091] The foregoing has shown and described the basic principles and main features of the present invention, as well as its advantages. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A high-nickel, cobalt-free cathode material doped with molybdenum and fluorine, characterized in that, The chemical formula of the molybdenum-fluorine dual-doped high-nickel cobalt-free cathode material is Li. a Ni x Mn y Mo 1-x-y F z O b Where 1≤a≤1.2, 1.9≤b≤2.1, 0.75≤x≤0.8, 0.02≤y≤0.2, 0.01≤z≤0.03; the molybdenum-fluorine dual-doped high-nickel cobalt-free cathode material has a particle size of 2-3μm and an R-3m layered structure inside the material.

2. The method for preparing a high-nickel, cobalt-free cathode material with molybdenum and fluorine dual doping according to claim 1, characterized in that, Includes the following steps: Step 1: Add nickel salt and manganese salt to deionized water at a molar mass ratio of (0.801-0.899):(0.101-0.199) and stir continuously to obtain solution A; Step 2: Mix ammonia water (25-28% ammonia content) and deionized water at a volume ratio of (0.1-0.6):1 and stir continuously for 60 minutes to obtain an ammonia solution. Step 3: Slowly add solution A to the ammonia solution at a rate of 0.1–0.8 mL / min using a peristaltic pump, while continuously stirring at 500–1000 rpm under nitrogen protection; simultaneously, add a 1–5 mol / L solution at a rate of 0.3–1 mL / min. -1 A sodium hydroxide solution was prepared, and the temperature of the entire system was maintained between 40 and 80°C, and the pH of the mixed solution was maintained between 10.2 and 11.

6. The mixture was stirred continuously for 24 to 48 hours, then allowed to stand at room temperature for 4 to 12 hours. After centrifugation, washing, and drying, the precursor Ni for nickel-manganese binary materials was obtained. x Mn 1-x (OH)₂, where 0.79 ≤ x ≤ 0.99; Step 4: Add the precursor Ni x Mn 1-x (OH)₂: molybdenum oxide: ammonium fluoride: lithium salt were mixed and ground in a molar ratio of 1:(0.05~0.09):(0.03~0.05):(1.01~1.08) for 30~60 min. The mixture was then heated at 850~1000℃ in an O₂ atmosphere at a heating rate of 1.0~3.0℃ / min for 10~20 h, and then naturally cooled to room temperature to obtain a high-nickel, cobalt-free cathode material, Li₂, which is doped with molybdenum and fluorine. a Ni x Mn y Mo 1-x-y F z O b , where 1≤a≤1.2, 1.9≤b≤2.1, 0.75≤x≤0.8, 0.02≤y≤0.2, and 0.01≤z≤0.

03.

3. The method for preparing a high-nickel, cobalt-free cathode material with molybdenum and fluorine dual doping according to claim 2, characterized in that, In step (1), the nickel salt is any one of nickel sulfate, nickel chloride, and nickel nitrate.

4. The method for preparing a high-nickel, cobalt-free cathode material with molybdenum and fluorine dual doping according to claim 2, characterized in that, In step (1), the manganese salt is any one of manganese sulfate, manganese chloride, and manganese nitrate.

5. The method for preparing a high-nickel, cobalt-free cathode material with molybdenum and fluorine dual doping according to claim 2, characterized in that, In step (4), the lithium salt is any one of lithium hydroxide, lithium carbonate, and lithium acetate.

6. The application of the molybdenum-fluorine dual-doped high-nickel cobalt-free cathode material according to claim 1, characterized in that: Applications as cathode materials for lithium-ion batteries.

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