High-conductivity ternary positive electrode material and preparation method thereof
By doping high-nickel polycrystalline and monocrystalline ternary materials with metal fluorides and borides, and by grading materials with different particle sizes, the problem of low electronic conductivity of high-nickel ternary cathode materials was solved, thereby improving the cycle performance and conductivity of lithium-ion batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GUANGDONG BRUNP RECYCLING TECH CO LTD
- Filing Date
- 2023-03-03
- Publication Date
- 2026-08-04
AI Technical Summary
The low electronic conductivity of existing high-nickel ternary cathode materials leads to poor cycle performance of lithium-ion batteries, which is difficult to improve effectively through common doping and coating methods.
A high-conductivity ternary cathode material is prepared by mixing high-nickel polycrystalline ternary materials and high-nickel single-crystal ternary materials, and by doping the core of the polycrystalline material with metal fluorides and the shell with metal borides, combined with high-temperature sintering and coating treatment. The cathode thickness is reduced and the electronic conductivity is improved by grading materials with different particle sizes.
It significantly improves the cycle performance of lithium-ion batteries and reduces cycle DC resistance, improves the electronic conductivity of materials, and enhances the structural stability and cycle performance of materials.
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Figure CN116247185B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium-ion battery materials technology, and more specifically, to a high-conductivity ternary cathode material and its preparation method. Background Technology
[0002] High-nickel ternary lithium nickel cobalt manganese oxide (Ni content ≥ 60%) is one of the most widely used cathode materials for lithium-ion batteries. Its low cost, long cycle life, and high energy density make it popular with consumers. While its advantages are obvious, its safety and cycle performance are slightly inferior to lithium iron phosphate. The safety performance of both high-nickel ternary and lithium iron phosphate batteries is mainly determined by the internal structure of the cathode material, which is generally difficult to change. However, the cycle performance of high-nickel ternary cathode materials can be optimized and improved through bulk doping and surface coating modifications to reach the level of lithium iron phosphate cathode materials.
[0003] To improve the cycle performance of high-nickel ternary cathode materials, researchers have optimized the ternary layered structure by doping with various transition metal elements and using various inorganic / organic coatings to improve the surface structure, thereby enhancing cycle performance. For example, related technologies disclose a boron-doped nickel-cobalt-manganese cathode material and its preparation method. Doping with boron stabilizes the crystal structure, improves high-temperature storage performance, and reduces battery gas generation. Related technologies also disclose a tungsten-doped boride-coated lithium-ion battery cathode material and its preparation method. The synergistic effect of w-doped boron coating improves both the internal structure and the external coating layer, thus enhancing cycle performance. Besides these common doping and coating methods to improve the internal structure and strengthen surface protection, other means can also be used to improve the surface electronic conductivity, thereby improving cycle performance.
[0004] The electronic conductivity of ternary materials is inversely proportional to their resistivity; the lower the resistivity, the higher the electronic conductivity. The resistivity of the powder material itself ultimately affects the resistance of the lithium-ion battery electrodes and exacerbates battery polarization, leading to poorer battery cycle life. The powder resistivity of the material is generally measured using the four-probe method. For thin film materials with certain conductivity, their charge transport performance along the planar direction is generally represented by sheet resistance. For a square thin film with side length l and thickness xj, its sheet resistance R can be expressed as:
[0005]
[0006] That is, the resistance R of a cubic thin film is directly proportional to the resistivity ρ and the film thickness x. jIt is inversely proportional to the square's side length l, and independent of the square's side length l. Therefore, when filling the same mass of ternary cathode material into a square cathode sheet, it can be found that if the filling thickness of the same mass of ternary cathode material can be reduced, it is equivalent to reducing the thickness of the cathode sheet. Thus, the improvement in the electronic conductivity of the ternary cathode material is equivalent to the effective improvement in the electronic conductivity of the cathode sheet.
[0007] In view of the above problems, it is necessary to provide a high-conductivity ternary cathode material and its preparation method. Summary of the Invention
[0008] The purpose of this invention is to overcome the defects of the prior art and provide a high-conductivity ternary cathode material and its preparation method.
[0009] The technical problem solved by this invention is achieved by the following technical solution.
[0010] This invention provides a high-conductivity ternary cathode material, comprising a uniformly mixed high-nickel polycrystalline ternary material and a high-nickel single-crystal ternary material. The median particle size of the high-nickel polycrystalline ternary material is 5.5-14.5 μm, and the median particle size of the high-nickel single-crystal ternary material is 2.0-4.0 μm. The mass ratio of the high-nickel polycrystalline ternary material to the high-nickel single-crystal ternary material is 0.5-9:1. The high-nickel polycrystalline ternary material has a core-shell structure, with its core doped with metal fluoride and its shell doped with metal boride. The high-nickel single-crystal ternary material is co-doped with metal fluoride and metal boride.
[0011] This invention also provides a method for preparing a high-conductivity ternary cathode material, comprising the following steps:
[0012] A high-nickel polycrystalline precursor with a median particle size of 5.0 μm-15.0 μm, a lithium-containing compound, and a metal fluoride are mixed evenly and sintered once. The crude product obtained from the first sintering, the lithium-containing compound, and the metal boride are mixed evenly and sintered a second time. After coating treatment, a modified high-nickel polycrystalline material with a median particle size of 5.5-14.5 μm is obtained.
[0013] A high-nickel single crystal precursor with a median particle size of 2.5-4.5 μm, a lithium-containing compound, a metal boride, and a metal fluoride are mixed evenly, sintered at high temperature, crushed, and then coated to obtain a modified high-nickel single crystal material with a median particle size of 2.0-4.0 μm.
[0014] Then, the high-nickel polycrystalline material and the high-nickel single-crystal material are graded according to the mass ratio determined by the volume density distribution ratio required in the particle size test to obtain a high-conductivity ternary cathode material.
[0015] The present invention also provides a lithium battery, wherein the positive electrode of the lithium battery comprises the above-mentioned high-conductivity ternary positive electrode material.
[0016] The present invention has the following beneficial effects:
[0017] This invention provides a high-conductivity ternary cathode material and its preparation method. The cathode material comprises two types of bulk particles doped with metal borides and metal fluorides. The large particles are high-nickel polycrystalline ternary materials with internal metal fluoride doping and a shell doping with metal borides, while the small particles are high-nickel single-crystal ternary materials co-doped with metal fluorides and metal borides. The high-conductivity ternary cathode material is obtained by matching the particle sizes. The ternary cathode material obtained through this gradation method can effectively reduce the stacking height of ternary cathode materials of the same mass, thereby indirectly reducing the thickness of the cathode sheet to optimize the electronic conductivity of the cathode sheet, improve the cycle performance of lithium-ion batteries, and reduce cycle damping rate (DCR). Attached Figure Description
[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1 This is a particle size distribution diagram of the large-particle high-nickel polycrystalline ternary cathode material in Comparative Example 1;
[0020] Figure 2 This is a particle size distribution diagram of the small-particle high-nickel single-crystal ternary cathode material in Comparative Example 2;
[0021] Figure 3 This is a particle size distribution diagram of the high-nickel ternary cathode material after gradation in Example 3;
[0022] Figure 4 This is a particle size distribution diagram of the high-nickel ternary cathode material after gradation in Example 4;
[0023] Figure 5 SEM image of the high-nickel ternary cathode material after gradation in Example 3;
[0024] Figure 6 This is a comparison chart of the cycle performance of high-nickel ternary cathode materials with large particles, small particles, and graded materials in Example 3;
[0025] Figure 7 This is a comparison chart of the cycle DCR of high-nickel ternary cathode materials with large particles, small particles, and graded materials in Example 3. Detailed Implementation
[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.
[0027] The following is a detailed description of a high-conductivity ternary cathode material and its preparation method provided by embodiments of the present invention.
[0028] In a first aspect, embodiments of the present invention provide a high-conductivity ternary cathode material, comprising a uniformly mixed high-nickel polycrystalline ternary material and a high-nickel single-crystal ternary material. The median particle size of the high-nickel polycrystalline ternary material is 5.5-14.5 μm, the median particle size of the high-nickel single-crystal ternary material is 2.0-4.0 μm, and the mass ratio of the high-nickel polycrystalline ternary material to the high-nickel single-crystal ternary material is 0.5-9:1. The high-nickel polycrystalline ternary material has a core-shell structure, with its core doped with metal fluoride and its shell doped with metal boride. The high-nickel single-crystal ternary material is co-doped with metal fluoride and metal boride.
[0029] In an optional embodiment, the doping amount of metal fluoride in the high-nickel polycrystalline ternary material is 0.02-1.0 wt%, and the doping amount of metal boride is 0.02-0.8 wt%; the doping amount of both metal fluoride and metal boride in the high-nickel single-crystal ternary material is 0.02-1.0 wt%.
[0030] In an optional implementation, the packing angle of the high-conductivity ternary cathode material is 25-40°.
[0031] Secondly, embodiments of the present invention provide a method for preparing a high-conductivity ternary cathode material, comprising the following steps:
[0032] A high-nickel polycrystalline precursor with a median particle size of 5.0 μm-15.0 μm, a lithium-containing compound, and a metal fluoride are mixed evenly and sintered once. The crude product obtained from the first sintering, the lithium-containing compound, and the metal boride are mixed evenly and sintered a second time. After coating treatment, a modified high-nickel polycrystalline material with a median particle size of 5.5-14.5 μm is obtained.
[0033] A high-nickel single crystal precursor with a median particle size of 2.5-4.5 μm, a lithium-containing compound, a metal boride, and a metal fluoride are mixed evenly, sintered at high temperature, crushed, and then coated to obtain a modified high-nickel single crystal material with a median particle size of 2.0-4.0 μm.
[0034] Then, the high-nickel polycrystalline material and the high-nickel single-crystal material are graded according to the mass ratio determined by the volume density distribution ratio required in the particle size test to obtain a high-conductivity ternary cathode material.
[0035] This invention provides a method for preparing a high-conductivity ternary cathode material. The cathode material includes two types of bulk particles doped with metal borides and metal fluorides. The large particles are core-shell structures, with the core doped with metal fluorides and the shell doped with metal borides. The small particles are high-nickel single-crystal ternary materials co-doped with metal fluorides and metal borides. The ternary cathode materials of different particle sizes are then graded. As can be seen from the above, the cathode material provided in the embodiments of the present invention improves the internal crystal structure by doping metal fluorides inside the large-particle high-nickel polycrystalline ternary material, and doping the outer shell with superconducting metal borides, thereby improving the electronic conductivity of the material shell structure and thus enhancing cycle performance. Small particles are simultaneously doped with metal fluorides and metal borides, which simultaneously improves the structural stability and electronic conductivity of the high-nickel single-crystal ternary material. Furthermore, by grading the large-particle ternary cathode material and the small-particle ternary cathode material, the thickness of the cathode sheet is reduced, thereby increasing the conductivity of the electrode sheet itself, and ultimately further improving the cycle performance and cycle DCR of the graded high-nickel ternary material.
[0036] In an optional embodiment, the high-nickel polycrystalline precursor is composed of Ni x M 1-x (OH)₂, wherein M is selected from at least two of Co, Mn, Al, Mg, Zn, V, Mo, W, Cu, and Sn, and 0.60 ≤ x < 1.00; the composition of the high-nickel single crystal precursor is Ni y M' 1-y (OH)2, wherein M' is at least two of Co, Mn, Al, Mg, Zn, V, Mo, W, Cu and Sn, and 0.6≤y<1.
[0037] In an optional embodiment, the metal fluoride has the composition AF. z Where A is at least one of Zr, Al, Mg, Y, Sn, Zn and Ce, 1≤z≤4, and the composition of the metal boride is M. x B y M is at least one of Ni, Mn, W, Nb, Mo, V, Y, La, Sr, Ta, Ce and Fe, 1≤x≤4, 1≤y≤6.
[0038] In an optional embodiment, the lithium-containing compound includes at least one of anhydrous LiOH, LiOH·H2O, lithium carbonate, lithium nitrate, lithium oxide, lithium acetate, and lithium oxalate.
[0039] In an optional embodiment, a high-nickel polycrystalline precursor with a median particle size of 5.0 μm-15.0 μm is mixed with a lithium-containing compound at a molar ratio of lithium content of the lithium-containing compound to total nickel, cobalt and manganese metal content in the high-nickel polycrystalline precursor of 0.8-1.0. At the same time, a metal fluoride is added at 0.02-1.0 wt% of the weight of the high-nickel polycrystalline precursor, and the mixture is sintered once at 400-600°C for 3-8 hours.
[0040] In an optional embodiment, the crude product obtained from the first sintering is supplemented with lithium-containing compounds at a molar ratio of lithium content of the lithium-containing compound to total nickel, cobalt and manganese metal content in the crude product obtained from the first sintering of 0-0.3, and at the same time, metal boride is supplemented at 0.02-0.8 wt% of the weight of the high-nickel polycrystalline precursor, and a second sintering is carried out at 600-850°C for 6-15 hours.
[0041] In an optional embodiment, a high-nickel single-crystal precursor with a median particle size of 2.5μm-4.5μm is mixed with a lithium-containing compound at a molar ratio of lithium content of the lithium-containing compound to total nickel, cobalt, and manganese metal content in the high-nickel single-crystal precursor of 1.0-1.1. Simultaneously, a metal fluoride is added at 0.02-1.0 wt% of the weight of the high-nickel single-crystal precursor, and a metal boride is added at 0.02-1.0 wt% of the weight of the high-nickel single-crystal precursor. The mixture is then sintered at 700-950°C for 8-16 hours.
[0042] As can be seen from the above, the present invention provides a method for preparing a high-conductivity ternary cathode material, including: preparing large-particle high-nickel polycrystalline ternary material using a two-stage sintering doping process, such as firstly incorporating metal fluoride doping into the precursor through a first-stage sintering process to improve the internal crystal structure, and then using a two-stage lithium supplementation sintering process to dope metal borides into the material shell layer, thereby improving the electronic conductivity of the material shell structure and thus enhancing cycle performance; preparing small-particle high-nickel single-crystal ternary material using a high-temperature sintering doping process, co-doping with metal fluoride and metal borides to simultaneously improve the structural stability and electronic conductivity of the small-particle high-nickel single-crystal ternary material; then grading the large-particle and small-particle ternary materials according to the mass ratio determined by the volume density distribution ratio requirement in the particle size test to reduce the thickness of the cathode sheet, thereby increasing the conductivity of the electrode sheet itself, and ultimately further improving the cycle performance and cycle DCR of the graded high-nickel ternary material.
[0043] Thirdly, embodiments of the present invention also provide a lithium battery, wherein the positive electrode of the lithium battery comprises the above-mentioned high-conductivity ternary positive electrode material.
[0044] The features and performance of the present invention will be further described in detail below with reference to embodiments.
[0045] The angle of repose in the following examples and comparative examples refers to the determination of the angle of repose in GB / T 6609.24-2004 Physical Properties.
[0046] Example 1
[0047] The preparation method of the high-conductivity ternary cathode material in this embodiment includes the following steps:
[0048] S1: A ternary precursor with a Dv50 of 15.0 μm and lithium hydroxide monohydrate were mixed at a molar ratio of lithium content in lithium hydroxide monohydrate to total nickel, cobalt, and manganese metal content in the ternary precursor of 0.8. ZrF4 was added at 0.05 wt% of the ternary precursor mass and sintered at 400 °C to obtain a crude product after one sintering. Then, an appropriate amount of lithium hydroxide monohydrate was added to the sample after one sintering at a molar ratio of lithium content in lithium hydroxide monohydrate to total nickel, cobalt, and manganese metal content in the crude product after one sintering of 0.3. At the same time, W2B was added at 0.05 wt% of the precursor mass. After mixing, the sample was sintered at 600 °C and the particle size of the sample was measured using a laser particle size analyzer. Then, a low-temperature coating treatment was performed to obtain the modified large-particle high-nickel ternary cathode material NCM811, and the particle size was measured using a laser particle size analyzer.
[0049] S2: Take another ternary precursor with Dv50 = 4.5μm and mix it with lithium hydroxide monohydrate at a molar ratio of lithium content of lithium hydroxide monohydrate to total nickel, cobalt and manganese metal content in the ternary precursor of 1.0. At the same time, add MoB and ZrF4 at 1wt% of the weight of the ternary precursor. After high-temperature sintering and crushing at 700℃, the particle size is tested by a laser particle size analyzer. Then, perform two low-temperature coating treatments to obtain the modified small-particle high-nickel ternary cathode material NCM811, and perform particle size testing.
[0050] S3: Finally, weigh the large-particle high-nickel ternary material and the small-particle high-nickel ternary material according to the required mass ratio of 9:1, and mix them in a high-efficiency mixer. After the mixture is uniform, the modified high-conductivity high-nickel ternary cathode material can be obtained, and the particle size can be tested.
[0051] Example 2
[0052] S1: A ternary precursor with a Dv50 of 5.0 μm and lithium hydroxide monohydrate were mixed at a molar ratio of lithium content in lithium hydroxide monohydrate to total nickel, cobalt, and manganese metal content in the ternary precursor of 1.0. AlF3 was added at 1.0 wt% of the ternary precursor mass and sintered at 600 °C to obtain a crude product after one sintering. Then, an appropriate amount of lithium hydroxide monohydrate was added to the sample after one sintering at a molar ratio of lithium content in lithium hydroxide monohydrate to total nickel, cobalt, and manganese metal content in the crude product after one sintering of 0.3. At the same time, NiB2 was added at 1.0 wt% of the precursor mass. After mixing, the sample was sintered at 850 °C and the particle size of the sample was measured using a laser particle size analyzer. Then, a low-temperature coating treatment was performed to obtain the modified large-particle high-nickel ternary cathode material NCM712, and the particle size was measured using a laser particle size analyzer.
[0053] S2: Take another ternary precursor with Dv50 = 2.5μm and lithium hydroxide monohydrate and mix them at a molar ratio of lithium content of lithium hydroxide monohydrate to total nickel, cobalt and manganese metal content in the ternary precursor of 1.1. At the same time, add MnB and AlF3 at 0.05wt% of the weight of the ternary precursor. After high-temperature sintering at 950℃ and crushing, the particle size is tested by a laser particle size analyzer. Then, perform a low-temperature coating treatment. Finally, the modified small-particle NCM712 high-nickel ternary cathode material is obtained and the particle size is tested.
[0054] S3: Finally, weigh the large-particle high-nickel ternary material and the small-particle high-nickel ternary material according to the required mass ratio of 0.5:1, and mix them in a high-efficiency mixer. After the mixture is uniform, the modified high-conductivity high-nickel ternary cathode material can be obtained, and the particle size can be tested.
[0055] Example 3
[0056] S1: A ternary precursor with a Dv50 of 10.5 μm and lithium hydroxide monohydrate were mixed at a molar ratio of lithium content in lithium hydroxide monohydrate to total nickel, cobalt, and manganese metal content in the ternary precursor of 0.9. MgF2 was added at 0.4 wt% of the ternary precursor mass and sintered at 500 °C to obtain a crude product after one sintering. Then, an appropriate amount of lithium hydroxide monohydrate was added to the sample after one sintering at a molar ratio of lithium content in lithium hydroxide monohydrate to total nickel, cobalt, and manganese metal content in the crude product after one sintering of 0.15. At the same time, TaB2 was added at 0.5 wt% of the precursor mass. After mixing, the sample was sintered at 730 °C and the particle size of the sample was measured using a laser particle size analyzer. Then, a low-temperature coating treatment was performed to obtain the modified large-particle high-nickel ternary cathode material NCM9055, and the particle size was measured using a laser particle size analyzer.
[0057] S2: Take another ternary precursor with Dv50 = 3.0μm and lithium hydroxide monohydrate and mix them at a molar ratio of lithium content of lithium hydroxide monohydrate to total nickel, cobalt and manganese metal content in the ternary precursor of 1.03. At the same time, add VB2 at 0.3wt% of the weight of the ternary precursor and ZrF4 at 0.6wt%. After high-temperature sintering at 800℃ and crushing, the particle size is tested by a laser particle size analyzer. Then, perform two low-temperature coating treatments to obtain modified small-particle NCM9055 high-nickel ternary cathode material, and perform particle size testing.
[0058] S3: Finally, weigh the large-particle high-nickel ternary material and the small-particle high-nickel ternary material according to the required mass ratio of 5:1, and mix them in a high-efficiency mixer. After the mixture is uniform, the modified high-conductivity high-nickel ternary cathode material can be obtained, and the particle size and angle of repose can be tested.
[0059] Example 4
[0060] S1: A ternary precursor with a Dv50 of 10.5 μm and lithium hydroxide monohydrate were mixed at a molar ratio of lithium content in lithium hydroxide monohydrate to total nickel, cobalt, and manganese metal content in the ternary precursor of 0.95. YF3 was added at 0.7 wt% of the ternary precursor mass, and the mixture was sintered at 500 °C to obtain a crude product after one sintering. Then, an appropriate amount of lithium hydroxide monohydrate was added to the sample after one sintering at a molar ratio of lithium content in lithium hydroxide monohydrate to total nickel, cobalt, and manganese metal content in the crude product after one sintering of 0.1. At the same time, NbB2 was added at 0.2 wt% of the precursor mass. After mixing, the mixture was sintered at 760 °C, and the particle size of the sample was measured using a laser particle size analyzer. Then, a low-temperature coating treatment was performed to obtain the modified large-particle high-nickel ternary cathode material NCM9055, and the particle size was measured using a laser particle size analyzer.
[0061] S2: Take another ternary precursor with Dv50 = 3.0μm and lithium hydroxide monohydrate and mix them at a molar ratio of lithium content of lithium hydroxide monohydrate to total nickel, cobalt and manganese metal content in the ternary precursor of 1.05. At the same time, add VB2 at 0.6wt% of the weight of the ternary precursor and CeF3 at 0.8wt%. After high-temperature sintering at 790℃ and crushing, the particle size is tested by a laser particle size analyzer. Then, perform two low-temperature coating treatments to obtain modified small-particle NCM9055 high-nickel ternary cathode material, and perform particle size testing.
[0062] S3: Finally, weigh the large-particle high-nickel ternary material and the small-particle high-nickel ternary material according to the required mass ratio of 2:1, and mix them in a high-efficiency mixer. After the mixture is uniform, the modified high-conductivity high-nickel ternary cathode material can be obtained, and the particle size and angle of repose can be tested.
[0063] Example 5
[0064] S1: A ternary precursor with a Dv50 of 7.5 μm and lithium hydroxide monohydrate were mixed at a molar ratio of lithium content in lithium hydroxide monohydrate to total nickel, cobalt, and manganese metal content in the ternary precursor of 0.92. ZrF4 was added at 0.3 wt% of the ternary precursor mass, and the mixture was sintered at 550 °C to obtain a crude product after one sintering. Then, an appropriate amount of lithium hydroxide monohydrate was added to the sample after the first sintering at a molar ratio of lithium content in lithium hydroxide monohydrate to total nickel, cobalt, and manganese metal content in the crude product after the first sintering of 0.14. CeB6 was added at 0.2 wt% of the precursor mass. After mixing, the mixture was sintered at 780 °C, and the particle size of the sample was measured using a laser particle size analyzer. Then, a low-temperature coating treatment was performed to obtain the modified large-particle high-nickel ternary cathode material NCM9055, and the particle size was measured using a laser particle size analyzer.
[0065] S2: Take another ternary precursor with Dv50 = 3.5μm and lithium hydroxide monohydrate and mix them at a molar ratio of lithium content of lithium hydroxide monohydrate to total nickel, cobalt and manganese metal content in the ternary precursor of 1.02. At the same time, add LaB6 at 0.1wt% of the weight of the ternary precursor and ZrF4 at 0.4wt%. After high-temperature sintering at 830℃ and crushing, the particle size is tested by a laser particle size analyzer. Then, perform a low-temperature coating treatment. Finally, the modified small-particle NCM811 high-nickel ternary cathode material is obtained and the particle size is tested.
[0066] S3: Finally, weigh the large-particle high-nickel ternary material and the small-particle high-nickel ternary material according to the required mass ratio of 4:1, and mix them in a high-efficiency mixer. After the mixture is uniform, the modified high-conductivity high-nickel ternary cathode material can be obtained, and the particle size can be tested.
[0067] Example 6
[0068] S1: A ternary precursor with a Dv50 of 10.5 μm and lithium hydroxide monohydrate were mixed at a molar ratio of lithium hydroxide monohydrate to total nickel, cobalt, and manganese metal content in the ternary precursor of 0.94. YF3 was added at 0.56 wt% of the ternary precursor mass and sintered at 500 °C to obtain a crude product after one sintering. Then, an appropriate amount of lithium hydroxide monohydrate was added to the sample after one sintering at a molar ratio of lithium hydroxide monohydrate to total nickel, cobalt, and manganese metal content in the crude product after one sintering of 0.09. At the same time, NbB2 was added at 0.25 wt% of the precursor mass. After mixing, the mixture was sintered at 745 °C and crushed to obtain modified large-particle NCM811 high-nickel ternary cathode material. The particle size of the obtained sample was measured using a laser particle size analyzer.
[0069] S2: Take another ternary precursor with Dv50 = 3.0μm and lithium hydroxide monohydrate and mix them at a molar ratio of lithium content of lithium hydroxide monohydrate to total nickel, cobalt and manganese metal content in the ternary precursor of 1.045. At the same time, add VB2 at 0.48wt% of the weight of the ternary precursor and CeF3 at 0.58wt%. After high-temperature sintering and crushing at 845℃, the modified small-particle NCM622 high-nickel ternary cathode material is obtained, and the particle size is tested by a laser particle size analyzer.
[0070] S3: Next, weigh the crushed samples from S1 and S2 according to the required mass ratio of 6:1, add the coating additives, mix them evenly in a high-efficiency mixer, and obtain the modified high-conductivity high-nickel ternary cathode material after low-temperature coating treatment, and then perform particle size testing.
[0071] Comparative Example 1
[0072] A ternary precursor with a Dv50 of 10.5 μm was mixed with lithium hydroxide monohydrate at a molar ratio of lithium content in lithium hydroxide monohydrate to total nickel, cobalt, and manganese metal content in the ternary precursor of 0.9. MgF2 was added simultaneously at 0.4 wt% of the ternary precursor mass, and the mixture was sintered at 500 °C to obtain a crude product after one sintering. Then, an appropriate amount of lithium hydroxide monohydrate was added to the sample after the first sintering at a molar ratio of lithium content in lithium hydroxide monohydrate to total nickel, cobalt, and manganese metal content in the crude product of the first sintering of 0.15. Simultaneously, TaB2 was added at 0.5 wt% of the precursor mass. After mixing, the mixture was sintered at 730 °C, and the particle size of the sample was measured using a laser particle size analyzer. A low-temperature coating treatment was then performed to obtain the modified large-particle high-nickel ternary cathode material NCM9055, and its particle size and angle of repose were measured using a laser particle size analyzer.
[0073] Comparative Example 2
[0074] Separately, a ternary precursor with a Dv50 of 3.0 μm was mixed with lithium hydroxide monohydrate at a molar ratio of lithium content in lithium hydroxide monohydrate to total nickel, cobalt, and manganese metal content in the ternary precursor of 1.03. At the same time, VB2 and ZrF4 were added at 0.3 wt% and 0.6 wt% of the cathode material weight, respectively. After high-temperature sintering at 800℃ and crushing, the particle size was tested using a laser particle size analyzer. Then, two low-temperature coating treatments were performed to obtain the modified small-particle NCM9055 high-nickel ternary cathode material, and the particle size and angle of repose were tested.
[0075] Comparative Example 3
[0076] A ternary precursor with a Dv50 of 10.5 μm was mixed with lithium hydroxide monohydrate at a molar ratio of lithium content in lithium hydroxide monohydrate to total nickel, cobalt and manganese metal content in the ternary precursor of 1.05. After mixing, the mixture was sintered at 730℃, and the particle size of the sample was measured using a laser particle size analyzer. Then, a low-temperature coating treatment was performed to obtain the modified large-particle high-nickel ternary cathode material NCM9055, and the particle size was measured using a laser particle size analyzer.
[0077] Comparative Example 4
[0078] Separately, a ternary precursor with Dv50 = 3.0 μm was mixed with lithium hydroxide monohydrate at a molar ratio of lithium content in lithium hydroxide monohydrate to total nickel, cobalt and manganese metal content in the ternary precursor of 1.03. After high-temperature sintering and crushing at 800℃, the particle size was tested using a laser particle size analyzer. Then, two low-temperature coating treatments were performed to obtain modified small-particle NCM9055 high-nickel ternary cathode material, and the particle size was tested.
[0079] Comparative Example 5
[0080] Similar to the steps in Example 1, the only difference is that the mass ratio of the large and small particles after conversion by volume density ratio is 10:1.
[0081] Comparative Example 6
[0082] Similar to the steps in Example 1, the only difference is that the mass ratio of the large and small particles after conversion by volume density ratio is 1:4.
[0083] Comparative Example 7
[0084] The steps are similar to those in Example 1, except that the doping amounts of ZrF4, W2B, and MoB used in the doping of the ternary materials of varying particle sizes are 1.05 wt%.
[0085] Comparative Example 8
[0086] The steps are similar to those in Example 1, except that the doping amounts of ZrF4, W2B, and MoB used in the doping of the ternary materials of different particle sizes are 0.01 wt%.
[0087] The bulk density distribution curves of the corresponding ternary lithium nickel cobalt manganese oxide materials in Comparative Examples 1 and 2 after testing with a Malvern laser particle size analyzer are shown below. Figure 1 and Figure 2 As shown in Examples 3 and 4, by adjusting... Figure 3 and Figure 4The volume density ratio of A to B shown is calculated using Origin software through simple peak splitting, resulting in a required particle size ratio of 5:1 and 2:1 for gradation. After comparison, it is evident that gradation of ternary nickel-cobalt-manganese lithium oxide materials with two different particle sizes will form new peaks at the smaller particle size. After peak splitting of the new peaks, the optimal particle size ratio can be obtained, thereby achieving the best effect of reducing powder resistivity. Figure 5 The image shown is an electron microscope image of Example 3 after bulk density gradation. It can be seen that this distribution effectively reduces dead zones in the packing, thereby reducing the packing height and improving powder resistivity. Simultaneously, from... Figure 6 and Figure 7 It can be seen that the cycle performance and DC resistance (DCR) of the ternary nickel-cobalt-manganese lithium oxide cathode material after gradation improvement in Example 3 are significantly better than those of single small-particle and large-particle ternary nickel-cobalt-manganese lithium oxide.
[0088] In Comparative Examples 5 and 6, the mixing ratio of large and small particles was adjusted according to the volume density distribution ratio to 10:1 and 1:4, respectively, outside the protection range. At these mixing ratios, the resistivity of the ternary material powder is also beneficial for both purely large and small particles, but the effect is not as good as within the 0.5-9:1 range. In Comparative Examples 7 and 8, increasing or decreasing the metal fluoride and boride content to outside the protection range also resulted in a series of problems such as excessively low positive electrode capacity and poor battery cycle life.
[0089] The powder resistivity of the samples in the above cases was characterized, as shown in Table 1 below.
[0090] Table 1: Comparison of resistivity of high-nickel ternary cathode material powders
[0091]
[0092] As can be seen from Comparative Examples 1-4, metal boride M x B y and metal fluorides AF z After doping and crushing, the powder resistivity of the large-particle ternary nickel-cobalt-manganese lithium oxide material decreased from 152 Ω·cm to 96 Ω·cm, and the powder resistivity of the small-particle ternary nickel-cobalt-manganese lithium oxide material decreased from 218 Ω·cm to 131 Ω·cm, showing a significant improvement in powder resistivity. Further improvements in gradation as described in Examples 3 and 4 revealed that the powder resistivity of the ternary nickel-cobalt-manganese lithium oxide material was also improved after gradation. Furthermore, the high-conductivity ternary cathode materials obtained after gradation, such as those in Examples 3 and 4, had packing angles of 29.82° and 33.29°, respectively, indicating that the packing angle of the graded materials also reflected the improved powder resistivity.
[0093] In summary, the embodiments of the present invention provide a high-conductivity ternary cathode material and its preparation method. The cathode material includes two bulk-doped metal borides M xB y (where 1≤x≤4, 1≤y≤6, and metal M is Ni, Mn, W, Nb, Mo, V, Y, La, Sr, Ta, Ce, Fe, etc.) and metal fluoride AF z (Where A represents Zr, Al, Mg, Y, Zn, Sn, and Ce, 1≤z≤4) The graded high-nickel ternary cathode material obtained after sintering and particle size matching, with metal boride M... x B y As a superconducting material, ternary cathode materials with different particle sizes are mixed in a mass ratio of (0.5-9):1. This invention improves the internal structural stability and external electronic conductivity of the ternary cathode material by doping with metal borides and metal fluorides. Furthermore, by distributing the ternary cathode materials with different particle sizes in different mass ratios, the stacking height of the ternary cathode material for the same mass can be effectively reduced, thereby indirectly reducing the thickness of the cathode sheet to optimize its electronic conductivity, improve the cycle performance of lithium-ion batteries, and reduce cycle damping rate (DCR).
[0094] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A high conductive ternary cathode material, characterized in that, The material comprises a uniformly mixed high-nickel polycrystalline ternary material and a high-nickel single-crystal ternary material. The median particle size of the high-nickel polycrystalline ternary material is 5.5-14.5 μm, and the median particle size of the high-nickel single-crystal ternary material is 2.0-4.0 μm. The mass ratio of the high-nickel polycrystalline ternary material to the high-nickel single-crystal ternary material is 0.5-9:
1. The packing angle of the high-conductivity ternary cathode material is 25-40°. The high-nickel polycrystalline ternary material has a core-shell structure, with the core doped with metal fluoride and the shell doped with metal boride. The high-nickel single-crystal ternary material is co-doped with metal fluoride and metal boride. The metal fluoride has the composition AF. z Where A is at least one of Zr, Al, Mg, Y, Sn, Zn and Ce, 1≤z≤4, and the composition of the metal boride is M. x B y M is at least one of Ni, Mn, W, Nb, Mo, V, Y, La, Sr, Ta, Ce and Fe, 1≤x≤4, 1≤y≤6, the doping amount of metal fluoride in the high-nickel polycrystalline ternary material is 0.02-1.0wt%, and the doping amount of metal boride is 0.02-0.8wt%; the doping amount of metal fluoride and metal boride in the high-nickel single-crystal ternary material is 0.02-1.0wt%.
2. The method for preparing the high-conductivity ternary cathode material according to claim 1, characterized in that, Includes the following steps: A high-nickel polycrystalline precursor with a median particle size of 5.0 μm-15.0 μm, a lithium-containing compound, and a metal fluoride are mixed evenly and sintered once. The crude product obtained from the first sintering, the lithium-containing compound, and the metal boride are mixed evenly and sintered a second time. After coating treatment, a modified high-nickel polycrystalline material with a median particle size of 5.5-14.5 μm is obtained. A high-nickel single-crystal precursor with a median particle size of 2.5-4.5 μm, a lithium-containing compound, a metal boride, and a metal fluoride are mixed evenly, sintered at high temperature, crushed, and then coated to obtain a modified high-nickel single-crystal material with a median particle size of 2.0-4.0 μm. The high-nickel polycrystalline material and the high-nickel single-crystal material are then graded according to the mass ratio determined by the volume density distribution ratio requirement in the particle size test to obtain the high-conductivity ternary cathode material.
3. The production method according to claim 2, characterized by, The high-nickel polycrystalline precursor is composed of Ni a M'' 1-a (OH)₂, wherein M'' is selected from at least two of Co, Mn, Al, Mg, Zn, V, Mo, W, Cu, and Sn, and 0.60 ≤ a < 1.00; the high-nickel single crystal precursor is composed of Ni b M' 1-b (OH)2, wherein M' is at least two of Co, Mn, Al, Mg, Zn, V, Mo, W, Cu and Sn, and 0.6 ≤ b < 1.
4. The preparation method according to claim 2, characterized in that, The metal fluoride has the composition AF. z Where A is at least one of Zr, Al, Mg, Y, Sn, Zn and Ce, 1≤z≤4, and the composition of the metal boride is M. x B y M is at least one of Ni, Mn, W, Nb, Mo, V, Y, La, Sr, Ta, Ce and Fe, 1≤x≤4, 1≤y≤6, and the lithium-containing compound includes at least one of anhydrous LiOH, LiOH·H2O, lithium carbonate, lithium nitrate, lithium oxide, lithium acetate and lithium oxalate.
5. The preparation method according to claim 2, characterized in that, The high-nickel polycrystalline precursor with a median particle size of 5.0 μm-15.0 μm is mixed with the lithium-containing compound at a molar ratio of lithium content of the lithium-containing compound to total nickel, cobalt and manganese metal content in the high-nickel polycrystalline precursor of 0.8-1.
0. At the same time, the metal fluoride is added at 0.02-1.0 wt% of the weight of the high-nickel polycrystalline precursor, and the mixture is sintered once at 400-600℃ for 3-8 hours.
6. The preparation method according to claim 2, characterized in that, The crude product obtained from the first sintering is supplemented with the lithium-containing compound at a molar ratio of 0-0.3 between the lithium content of the lithium-containing compound and the total nickel, cobalt and manganese metal content in the crude product obtained from the first sintering, and the metal boride is supplemented at 0.02-0.8 wt% of the weight of the high-nickel polycrystalline precursor. The mixture is then subjected to a second sintering at 600-850°C for 6-15 hours.
7. The preparation method according to claim 2, characterized in that, The high-nickel single-crystal precursor with a median particle size of 2.5-4.5 μm and the lithium-containing compound are mixed at a molar ratio of lithium content of the lithium-containing compound to total nickel, cobalt and manganese metal content in the high-nickel single-crystal precursor of 1.0-1.
1. At the same time, the metal fluoride and the metal boride are added at 0.02-1.0 wt% of the weight of the high-nickel single-crystal precursor, and the mixture is sintered at 700-950℃ for 8-16 h.
8. A lithium battery, characterized by The lithium battery cathode comprises the high-conductivity ternary cathode material as described in claim 1.