Cobalt-free ultrahigh nickel positive electrode material and preparation method and application thereof

Abstract

The invention relates to a cobalt-free ultra-high nickel positive electrode material and a preparation method and application thereof, the preparation method comprises the following steps: ball-milling and mixing a nickel source, a lithium source and a dopant to obtain powder, and drying and sintering the obtained powder to obtain the cobalt-free ultra-high nickel positive electrode material, the doping agent comprises an aluminum-containing doping agent and a manganese-containing doping agent; the nickel source, the lithium source and the doping agent are mixed according to the molar ratio of the nickel element to the lithium element to the total doping element being (0.90-0.98): (1.03-1.06): (0.02-0.10). The Al and Mn elements are uniformly doped in the positive electrode material substrate through a solid-phase reaction method, the material performance is synergistically improved by utilizing the unique action mechanism of the doped elements, the electrochemical performance is synergistically improved on the premise of not depending on the cobalt element, and high initial discharge capacity, cycling stability and rate capability are kept in a wide voltage interval; and excellent capacity retention capability is shown in a wide multiplying power range.

Description

Technical Field

[0001] This invention relates to the field of cathode material technology, specifically to a cobalt-free ultra-high nickel cathode material, its preparation method, and its application. Background Technology

[0002] As a core component of lithium-ion batteries, cathode materials directly affect the overall performance of the battery. Among them, the cobalt-free ultra-high nickel cathode material LiNiO2 does not rely on cobalt, which not only reduces production costs but also alleviates supply chain risks such as cobalt resource scarcity and ethical procurement, thus aligning with global sustainable development goals.

[0003] Existing cobalt-free ultra-high nickel cathode materials will form strongly oxidizing Ni under high voltage conditions. 4+ This leads to oxygen loss and interfacial side reactions, resulting in rapid capacity decay and poor cycle stability. Simultaneously, existing doped materials often suffer from insufficient rate performance, exhibiting severe capacity decay at high current densities, limiting their application in scenarios requiring fast charging performance, such as electric vehicles. Therefore, developing a cobalt-free ultra-high nickel cathode material with stable cycle performance and excellent rate performance has become a major challenge. Summary of the Invention

[0004] This invention provides a cobalt-free ultra-high nickel cathode material, its preparation method, and its application, in order to solve the problem that cobalt-free ultra-high nickel cathode materials cannot effectively balance good cycle stability and rate performance.

[0005] In a first aspect, the present invention provides a method for preparing a cobalt-free ultra-high nickel cathode material, comprising: ball milling and mixing a nickel source, a lithium source and a dopant and drying the mixture to obtain a powder, and sintering the obtained powder to obtain a cobalt-free ultra-high nickel cathode material. The dopants include aluminum-containing dopants and manganese-containing dopants; The nickel source, lithium source, and dopant are mixed in a ratio of nickel element: lithium element: total doped metal element of 0.90-0.98:1.03-1.06:0.02-0.10.

[0006] In one alternative embodiment, the nickel source comprises Ni(OH)2; The lithium source includes LiOH; The aluminum-containing dopant includes aluminum oxide; The manganese-containing dopant includes manganese oxide; The alumina and manganese oxide are selected from nano-grade high-purity oxides.

[0007] In the total doped metal elements, the molar ratio of aluminum to manganese is 1:0.25-4.

[0008] In one optional embodiment, the ball milling mixing is carried out at 20-40°C; The ball milling time is 3-5 hours.

[0009] The ball milling is operated intermittently, and the specific "milling" and "stopping" times are not limited. The only requirement is that the slurry temperature during the ball milling process does not exceed 40°C.

[0010] In one alternative embodiment, the particle size of the powder is 1-3 μm.

[0011] In one alternative implementation, the drying is performed using a forced-air drying method.

[0012] In one optional embodiment, the drying temperature of the blower drying is 70-90°C, and the drying time is 6-8 hours.

[0013] In one alternative embodiment, the sintering includes sintering in an oxygen atmosphere.

[0014] In one optional embodiment, the sintering heating rate is 3-5℃ / min, the sintering temperature is 700-800℃, and the sintering time is 10-15h.

[0015] Secondly, the present invention also provides a cobalt-free ultra-high nickel cathode material, which is prepared by the above-described preparation method.

[0016] Thirdly, the present invention also provides an application of the above-mentioned cobalt-free ultra-high nickel cathode material in a battery.

[0017] The technical solution of this invention has the following advantages: 1. The present invention provides a method for preparing a cobalt-free ultra-high nickel cathode material, the method comprising: ball milling and mixing a nickel source, a lithium source and a dopant to obtain a powder, drying and sintering the obtained powder to obtain a cobalt-free ultra-high nickel cathode material; the dopant includes an aluminum-containing dopant and a manganese-containing dopant; the nickel source, the lithium source and the dopant are mixed in a ratio of nickel element: lithium element: total dopant element molar ratio of 0.90-0.98:1.03-1.06:0.02-0.10.

[0018] This invention utilizes a solid-state reaction method to uniformly dope Al and Mn elements into a cathode material substrate. By leveraging the unique mechanisms of these dopants, the material's performance is synergistically improved. Al, by suppressing Li / Ni cation mixing, helps maintain the stability of the layered structure, enhancing electrochemical performance and rate capability. Mn, by alleviating lattice strain, ensures ion transport efficiency. This synergistic effect, without relying on cobalt, achieves a significant improvement in electrochemical performance, maintaining high initial discharge capacity, cycle stability, and rate capability over a wide voltage range, and exhibiting excellent capacity retention over a wide rate range. The essence of aluminum and manganese co-doping is complementary performance: Al... 3+ Focusing on bulk structural stability, suppressing harmful phase transitions, reducing cation cross-contamination, and optimizing electron conduction. Mn 4+ It focuses on interface protection, inhibits oxygen loss, maintains particle integrity, and improves thermal stability. This synergistic effect solves the problems of structural collapse and capacity decay in cobalt-free ultra-high nickel cathodes under high voltage.

[0019] In addition, the material does not contain cobalt, which avoids dependence on cobalt resources and reduces production costs. It also relies on the simplified process of solid-state reaction, which does not require complex equipment and expensive reagents, resulting in low energy consumption and a controllable process. At the same time, its combined advantages of high energy density, long cycle life and excellent fast-charging performance give it outstanding industrialization value and market prospects. Detailed Implementation

[0020] The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0021] Unless otherwise specified, all experimental steps or conditions in the examples were performed according to conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0022] Example 1 This embodiment provides a method for preparing a cobalt-free ultra-high nickel cathode material, including the following steps: Raw material selection: spherical Ni(OH)2 (purity 99.9%), LiOH H2O (purity 99.5%), nano-sized Al2O3 (purity 99.99%, particle size 5-10nm), nano-sized MnO2 (purity 98%, particle size 50-100nm); Ingredient mixing: Ni(OH)2, LiOH The raw materials, H2O, Al2O3, and MnO2, were weighed with a nickel:lithium:aluminum:manganese molar ratio of 0.96:1.06:0.02:0.02. Anhydrous ethanol was added as the dispersion medium for ball milling. The ball milling was carried out intermittently with a "1 hour ball milling + 10 minute stop" operation to control the slurry temperature to not exceed 40°C during the ball milling process. The ball-to-material ratio was 10:1, the ball milling speed was 300 rpm, and the ball milling time was 5 hours. After ball milling, the particle size of the raw material was refined to 3 μm or less. Drying treatment: The ball-milled slurry was placed in an 80℃ forced-air drying oven and dried for 7 hours to obtain a dried mixed powder; Sintering: The dry powder is placed in a tube furnace for sintering. Sintering is carried out in an oxygen atmosphere, including heating to 750°C at a heating rate of 4°C / min, holding at that temperature for 12 hours, and then naturally cooling to room temperature to obtain an aluminum-manganese co-doped cobalt-free ultra-high nickel cathode material.

[0023] Example 2 This embodiment provides a method for preparing a cobalt-free ultra-high nickel cathode material, including the following steps: Raw material selection: spherical Ni(OH)2 (purity 99.9%), LiOH H2O (purity 99.5%), nano-sized Al2O3 (purity 99.99%, particle size 5-10nm), nano-sized MnO2 (purity 98%, particle size 50-100nm); Ingredient mixing: Ni(OH)2, LiOH The raw materials, H2O, Al2O3, and MnO2, were weighed with a nickel:lithium:aluminum:manganese molar ratio of 0.92:1.06:0.04:0.04. Anhydrous ethanol was added as the dispersion medium for ball milling. The ball milling was carried out intermittently with a "1 hour ball milling + 10 minute stop" operation to control the slurry temperature to not exceed 40°C during the ball milling process. The ball-to-material ratio was 15:1, the ball milling speed was 500 rpm, and the ball milling time was 3 hours. After ball milling, the particle size of the raw materials was refined to 3 μm and below. Drying treatment: The ball-milled slurry was placed in a 70℃ forced-air drying oven and dried for 8 hours to obtain a dried mixed powder; Sintering: The dry powder is placed in a tube furnace for sintering. Sintering is carried out in an oxygen atmosphere, including heating to 800°C at a heating rate of 5°C / min, holding at that temperature for 10 hours, and then naturally cooling to room temperature to obtain an aluminum-manganese co-doped cobalt-free ultra-high nickel cathode material.

[0024] Example 3 This embodiment provides a method for preparing a cobalt-free ultra-high nickel cathode material, including the following steps: Raw material selection: spherical Ni(OH)2 (purity 99.9%), LiOH H2O (purity 99.5%), nano-sized Al2O3 (purity 99.99%, particle size 5-10nm), nano-sized MnO2 (purity 98%, particle size 50-100nm); Ingredient mixing: Ni(OH)2, LiOH The raw materials, H2O, Al2O3, and MnO2, were weighed with a nickel:lithium:aluminum:manganese molar ratio of 0.98:1.06:0.01:0.01. Anhydrous ethanol was added as the dispersion medium for ball milling. The ball milling was carried out intermittently with a "1 hour ball milling + 10 minute stop" operation to control the slurry temperature to not exceed 40°C during the ball milling process. The ball-to-material ratio was 10:1, the ball milling speed was 400 rpm, and the ball milling time was 4 hours. After ball milling, the particle size of the raw materials was refined to 3 μm and below. Drying treatment: The ball-milled slurry was placed in a 90℃ forced-air drying oven and dried for 6 hours to obtain a dried mixed powder; Sintering: The dry powder is placed in a tube furnace for sintering. Sintering is carried out in an oxygen atmosphere, including heating to 750°C at a heating rate of 4°C / min, holding at that temperature for 12 hours, and then naturally cooling to room temperature to obtain an aluminum-manganese co-doped cobalt-free ultra-high nickel cathode material.

[0025] Example 4 This embodiment provides a method for preparing a cobalt-free ultra-high nickel cathode material, including the following steps: Raw material selection: spherical Ni(OH)2 (purity 99.9%), LiOH H2O (purity 99.5%), nano-sized Al2O3 (purity 99.99%, particle size 5-10nm), nano-sized MnO2 (purity 98%, particle size 50-100nm); Ingredient mixing: Ni(OH)2, LiOH The raw materials, H2O, Al2O3, and MnO2, were weighed with a nickel:lithium:aluminum:manganese molar ratio of 0.90:1.06:0.08:0.02. Anhydrous ethanol was added as the dispersion medium for ball milling. The ball milling was carried out intermittently with a "1 hour ball milling + 10 minute stop" operation to control the slurry temperature to not exceed 40°C during the ball milling process. The ball-to-material ratio was 10:1, the ball milling speed was 400 rpm, and the ball milling time was 4 hours. After ball milling, the particle size of the raw material was refined to 3 μm or less. Drying treatment: The ball-milled slurry was placed in an 80℃ forced-air drying oven and dried for 7 hours to obtain a dried mixed powder; Sintering: The dry powder is placed in a tube furnace for sintering. Sintering is carried out in an oxygen atmosphere, including heating to 800°C at a heating rate of 3°C / min, holding at that temperature for 10 hours, and then naturally cooling to room temperature to obtain an aluminum-manganese co-doped cobalt-free ultra-high nickel cathode material.

[0026] Example 5 This embodiment provides a method for preparing a cobalt-free ultra-high nickel cathode material, including the following steps: Raw material selection: spherical Ni(OH)2 (purity 99.9%), LiOH H2O (purity 99.5%), nano-sized Al2O3 (purity 99.99%, particle size 5-10nm), nano-sized MnO2 (purity 98%, particle size 50-100nm); Ingredient mixing: Ni(OH)2, LiOH The raw materials, H2O, Al2O3, and MnO2, were weighed with a nickel:lithium:aluminum:manganese molar ratio of 0.90:1.06:0.02:0.08. Anhydrous ethanol was added as the dispersion medium for ball milling. The ball milling was carried out in an intermittent manner with "1 hour of ball milling + 10 minutes of rest" to control the slurry temperature to not exceed 40°C during the ball milling process. The ball-to-material ratio was 10:1, the ball milling speed was 400 rpm, and the ball milling time was 4 hours. Drying treatment: The ball-milled slurry was placed in an 80℃ forced-air drying oven and dried for 7 hours to obtain a dried mixed powder; Sintering: The dry powder is placed in a tube furnace for sintering. Sintering is carried out in an oxygen atmosphere, including heating to 800°C at a heating rate of 3°C / min, holding at that temperature for 10 hours, and then naturally cooling to room temperature to obtain an aluminum-manganese co-doped cobalt-free ultra-high nickel cathode material.

[0027] Comparative Example 1 This comparative example provides a method for preparing a cobalt-free ultra-high nickel cathode material, including the following steps: Raw material selection: spherical Ni(OH)2 (purity 99.9%), LiOH H2O (purity 99.5%), nano-sized Al2O3 (purity 99.99%, particle size 5-10nm); Ingredient mixing: Ni(OH)2, LiOH The raw materials, H2O and Al2O3, were weighed with a nickel:lithium:aluminum molar ratio of 0.96:1.06:0.02. Anhydrous ethanol was added as the dispersion medium for ball milling. The ball milling was carried out intermittently with a "1 hour ball milling + 10 minute stop" operation to control the slurry temperature to not exceed 40°C during the ball milling process. The ball-to-material ratio was 10:1, the ball milling speed was 300 rpm, and the ball milling time was 5 hours. After ball milling, the particle size of the raw material was refined to 3 μm and below. Drying treatment: The ball-milled slurry was placed in an 80℃ forced-air drying oven and dried for 7 hours to obtain a dried mixed powder; Sintering: The dry powder is placed in a tube furnace for sintering. Sintering is carried out in an oxygen atmosphere, including heating to 750°C at a heating rate of 4°C / min, holding at that temperature for 12 hours, and then naturally cooling to room temperature to obtain an aluminum-doped cobalt-free ultra-high nickel cathode material.

[0028] Comparative Example 2 This comparative example provides a method for preparing a cobalt-free ultra-high nickel cathode material, including the following steps: Raw material selection: spherical Ni(OH)2 (purity 99.9%), LiOH H2O (purity 99.5%), nano-sized MnO2 (purity 98%, particle size 50-100nm); Ingredient mixing: Ni(OH)2, LiOH The raw materials, H2O and MnO2, were weighed with a nickel:lithium:manganese molar ratio of 0.96:1.06:0.02. Anhydrous ethanol was added as the dispersion medium for ball milling. The ball milling was carried out intermittently with a "1 hour ball milling + 10 minute stop" operation to control the slurry temperature to not exceed 40°C during the ball milling process. The ball-to-material ratio was 10:1, the ball milling speed was 300 rpm, and the ball milling time was 5 hours. After ball milling, the particle size of the raw material was refined to 3 μm and below. Drying treatment: The ball-milled slurry was placed in an 80℃ forced-air drying oven and dried for 7 hours to obtain a dried mixed powder; Sintering: The dry powder is placed in a tube furnace for sintering. Sintering is carried out in an oxygen atmosphere, including heating to 750°C at a heating rate of 4°C / min, holding at that temperature for 12 hours, and then naturally cooling to room temperature to obtain a manganese-doped cobalt-free ultra-high nickel cathode material.

[0029] Comparative Example 3 This comparative example provides a method for preparing a cobalt-free ultra-high nickel cathode material, including the following steps: Raw material selection: spherical Ni(OH)2 (purity 99.9%), LiOH H2O (purity 99.5%) Ingredient mixing: Ni(OH)2, LiOH The raw materials were weighed with a nickel:lithium molar ratio of 0.96:1.06 in H2O. Anhydrous ethanol was added as the dispersion medium for ball milling. The ball milling was carried out intermittently with a "1 hour ball milling + 10 minute stop" operation to control the slurry temperature to not exceed 40°C during the ball milling process. The ball-to-material ratio was 10:1, the ball milling speed was 300 rpm, and the ball milling time was 5 hours. After ball milling, the particle size of the raw material was refined to 3 μm and below. Drying treatment: The ball-milled slurry was placed in an 80℃ forced-air drying oven and dried for 7 hours to obtain a dried mixed powder; Sintering: The dry powder is placed in a tube furnace for sintering. Sintering is carried out in an oxygen atmosphere, including heating to 750°C at a heating rate of 4°C / min, holding at that temperature for 12 hours, and then naturally cooling to room temperature to obtain a cobalt-free ultra-high nickel cathode material.

[0030] Comparative Example 4 Raw material selection: spherical Ni(OH)2 (purity 99.9%), LiOH H2O (purity 99.5%), nano-sized Al2O3 (purity 99.99%, particle size 5-10nm), nano-sized MnO2 (purity 98%, particle size 50-100nm); Ingredient mixing: Ni(OH)2, LiOH The raw materials, H2O, Al2O3, and MnO2, were weighed with a nickel:lithium:aluminum:manganese molar ratio of 0.96:1.06:0.10:0.10. Anhydrous ethanol was added as the dispersion medium for ball milling. The ball milling was carried out intermittently with a "1 hour ball milling + 10 minute stop" operation to control the slurry temperature to not exceed 40°C during the ball milling process. The ball-to-material ratio was 10:1, the ball milling speed was 300 rpm, and the ball milling time was 5 hours. After ball milling, the particle size of the raw material was refined to 3 μm and below. Drying treatment: The ball-milled slurry was placed in an 80℃ forced-air drying oven and dried for 7 hours to obtain a dried mixed powder; Sintering: The dry powder is placed in a tube furnace for sintering. Sintering is carried out in an oxygen atmosphere, including heating to 750°C at a heating rate of 4°C / min, holding at that temperature for 12 hours, and then naturally cooling to room temperature to obtain an aluminum-manganese co-doped cobalt-free ultra-high nickel cathode material.

[0031] Experimental Example 1 1. Electrochemical performance testing The cathode materials prepared in Examples 1-5 and Comparative Examples 1-4 were used to fabricate coin cells, and their electrochemical performance was tested. The process included: weighing the doped cathode material, conductive carbon black, and PVDF binder at a mass ratio of 96:2:2, adding an appropriate amount of N-methylpyrrolidone solvent (solid content controlled at 50%), and stirring at 1000 rpm for 5 hours in a planetary mixer to prepare a uniform slurry; then coating the slurry onto a 20-micron thick aluminum foil current collector using a 120-micron doctor blade, controlling the wet film thickness to 150 microns, and subsequently drying it in a vacuum oven at 110°C for 12 hours; next, compacting the electrode sheet to a density of 3.5 g / cm³ using a roller mill under 120 MPa pressure, and punching it into a 12 mm diameter disc; finally, assembling a CR2032 type coin cell in an argon-protected glove box, using a lithium metal sheet as the counter electrode. The separator was 2400, and an EC / DEC electrolyte of 1 mol / L LiPF6 (volume ratio 1:1) was injected, with the electrolyte volume for each battery precisely controlled at 100 μL. Using the Blue Electric CT3001 testing system, initial charge-discharge tests were conducted at a rate of 0.1C within a voltage range of 3.0–4.3V, followed by cycle performance tests at a rate of 1C (100 cycles). The test environment temperature was 25 ± 2℃. The test results are shown in Table 1.

[0032] Table 1 Performance test results of batteries prepared with cathode materials from the examples and comparative examples.

[0033] As can be seen from the data in Table 1, although the undoped Comparative Example 3 had the highest initial discharge capacity (220.1 mAh / g), its initial coulombic efficiency (86.7%), capacity retention after 100 cycles (75.3%), and rate performance (62.4%) were the worst. Comparing Comparative Example 3 with Examples 1-5 demonstrates that aluminum-manganese co-doping significantly improves the cycle stability and rate performance of the cathode material. Comparative Examples 1 and 2, doped with pure aluminum or pure manganese, showed improved performance, but still lagged behind the aluminum-manganese co-doped Examples 1-5. The co-doped samples all achieved initial coulombic efficiencies above 92.5%, and capacity retention after 100 cycles ranged from 85.7% to 93.1%. Their 1C / 0.1C capacity utilization was also superior to the single-doped and undoped samples. Comparative Example 4, with its excessively high total doping content, exhibited unsatisfactory performance across all aspects, demonstrating the crucial importance of controlling the doping element content. Example 2 exhibited the best overall performance, balancing high coulombic efficiency, excellent cycle stability, and rate performance.

[0034] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a cobalt-free ultra-high nickel cathode material, characterized in that, The preparation method includes: Nickel source, lithium source and dopant are ball-milled and mixed and then dried to obtain powder. The obtained powder is then sintered to obtain cobalt-free ultra-high nickel cathode material. The dopants include aluminum-containing dopants and manganese-containing dopants; The nickel source, lithium source, and dopant are mixed in a ratio of nickel element: lithium element: total doped metal element of 0.90-0.98:1.03-1.06:0.02-0.

10.

2. The preparation method according to claim 1, characterized in that, The nickel source includes Ni(OH)2; And / or, the lithium source includes LiOH; And / or, the aluminum-containing dopant includes aluminum oxide; And / or, the manganese-containing dopant includes manganese oxide; And / or, in the total doped metal elements, the molar ratio of aluminum to manganese is 1:0.25-4.

3. The preparation method according to claim 1, characterized in that, The ball milling and mixing are carried out at 20-40°C. And / or, the ball milling time is 3-5 hours.

4. The preparation method according to claim 1, characterized in that, The particle size of the powder is 1-3 μm.

5. The preparation method according to claim 1, characterized in that, The drying process employs a forced-air drying method.

6. The preparation method according to claim 5, characterized in that, The drying temperature of the blower drying is 70-90℃, and the drying time is 6-8 hours.

7. The preparation method according to claim 1, characterized in that, The sintering includes sintering in an oxygen atmosphere.

8. The preparation method according to claim 7, characterized in that, The sintering heating rate is 3-5℃ / min, the sintering temperature is 700-800℃, and the sintering time is 10-15h.

9. A cobalt-free ultra-high nickel cathode material, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

10. The application of the cobalt-free ultra-high nickel cathode material as described in claim 9 in a battery.

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