Modified ultra-high-nickel positive electrode material, preparation method and application thereof
By employing rapid heating, short-time two-stage sintering, and doping modification methods, the problem of residual alkali on the surface of ultra-high nickel cathode materials was solved. This approach effectively reduced residual alkali while maintaining material performance, simplified the process, and lowered costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GEM WUXI ENERGY MATERIAL CO LTD
- Filing Date
- 2026-06-24
- Publication Date
- 2026-07-24
AI Technical Summary
In the preparation of ultra-high nickel cathode materials, existing technologies have difficulty in effectively removing residual lithium salts from the surface, which leads to slurry gelation, narrowing of the electrode processing window, increased gas generation during charge and discharge, instability of the interface film, and decreased cycle performance. Moreover, existing methods are complex and costly, making it difficult to achieve both efficient residual reduction and preservation of material performance.
A combination of rapid heating and short-time two-stage sintering process with doping modification was adopted. By simultaneously reducing residual alkali during the lithiation sintering stage, dopants such as Al2O3, Al(OH)3, and Al2(SO4)3 were used to control the lithiation reaction conditions, suppress lithium-nickel mixing, and stabilize the layered crystal structure.
Significantly reduces residual alkaline substances on the surface of ultra-high nickel cathode materials, maintains the discharge specific capacity and cycle stability of the materials, reduces water washing and acid washing steps, reduces energy consumption and time costs, and achieves synergistic optimization of material processing performance and electrochemical performance.
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Figure CN122444237A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium-ion batteries, specifically to a modified ultra-high nickel cathode material, its preparation method, and its application. Background Technology
[0002] Ultra-high nickel layered oxide cathode materials have become important candidate materials for power batteries and energy storage batteries due to their high discharge specific capacity and energy density. However, with the increase of nickel content, the material becomes increasingly sensitive to the lithiation sintering process, oxygen partial pressure, venting conditions, residual lithium salts on the surface, and particle densification. In industrial production, these materials are usually prepared by mixing a hydroxide precursor with a lithium source and then sintering at high temperature in an oxygen atmosphere. Due to the narrow lithiation reaction window and high surface activity of ultra-high nickel materials, residual lithium salts (residual alkalis) such as LiOH and Li2CO3 are easily generated on the surface during sintering due to insufficient dehydration and decomposition of the lithium source, untimely removal of H2O / CO2, or fluctuations in oxygen partial pressure. These residual alkalis can cause a series of problems such as slurry gelation, narrowing of the electrode processing window, increased gas generation during charge and discharge, unstable interfacial film, and decreased cycle performance, which seriously restricts its large-scale commercial application.
[0003] Currently, methods for reducing residual alkali on the surface of ultra-high nickel cathode materials mostly rely on post-treatment methods such as water washing, acid washing, coating modification, secondary heat treatment, or adding reactive substances to consume residual alkali. However, while water washing can dissolve and remove residual alkali, it can also lead to the degradation of Li. + / H + Exchange can lead to lithium-nickel mixing or lithium deficiency in the crystal lattice, resulting in capacity loss and cycle degradation, while also increasing wastewater treatment costs. Acid washing introduces residual acid ions, causing corrosive damage to the crystal structure. Methods such as coating, secondary sintering, or adding weak acid salts require additional steps like wet / dry mixing and secondary calcination, extending the sintering cycle, increasing furnace occupancy time and energy consumption, and making it difficult to stably control the interfacial compatibility and stability of the coating layer. Overall, existing technologies follow a "synthesize first, then process" approach. While they offer some residual reduction, they generally involve increased process complexity, higher costs, surface structure damage, or performance degradation, making it difficult to simultaneously achieve efficient residual reduction and maintain the intrinsic properties of the material.
[0004] Therefore, there is an urgent need for a preparation method that is compatible with existing ultra-high nickel cathode material production lines, requires no additional washing or secondary heat treatment processes, has lower energy and time costs, and can reduce surface residual alkali in situ while maintaining material capacity and stability. Summary of the Invention
[0005] This invention provides a modified ultra-high nickel cathode material, its preparation method, and its application to solve the above-mentioned problems.
[0006] In a first aspect, the present invention provides a method for preparing a modified ultra-high nickel cathode material, comprising the following steps: S1, mixing an ultra-high nickel ternary precursor, a lithium source, and a dopant to obtain a mixture; wherein the dopant includes an Al-containing compound; S2, subjecting the mixture to a first sintering, a second sintering, cooling, crushing, and demagnetizing to obtain the modified ultra-high nickel cathode material; wherein the temperature of the first sintering is 450-600℃, the heating rate is 10-20℃ / min, and the holding time is 0.5-2h; and the temperature of the second sintering is 680-750℃, the heating rate is 10-20℃ / min, and the holding time is 1-5h.
[0007] In one optional embodiment, the amount of the dopant added accounts for 0.5-2 mol% of the total molar amount of transition metal in the ultra-high nickel ternary precursor. In one optional embodiment, the general chemical formula of the ultra-high nickel ternary precursor is Ni. x Co y A z (OH)2, wherein 0.90≤x≤0.98, 0.01≤y≤0.05, 0.01≤z≤0.05, x+y+z=1, and A is at least one of Mn and Al; In one alternative embodiment, the D50 of the modified ultra-high nickel cathode material is 3-10 μm.
[0008] In one optional embodiment, the ratio of the total molar number (Me) of Li in the lithium source to the total number of transition metals in the ultra-high nickel ternary precursor is (1.00-1.05):1.
[0009] In one optional embodiment, the dopant includes at least one of aluminum oxide, aluminum hydroxide, and aluminum salts; Optionally, the aluminum salt includes at least one of aluminum sulfate and aluminum nitrate.
[0010] In one optional embodiment, the lithium source includes at least one of lithium hydroxide and lithium carbonate.
[0011] In one alternative embodiment, the atmosphere for the first sintering, the second sintering, and the cooling is independently an oxygen atmosphere; Optionally, the oxygen volume fraction of the oxygen atmosphere is 98.5% to 99.9%.
[0012] In one optional embodiment, the magnetic field strength for demagnetization is 8000–12000 Gs, and the number of times is 1–3.
[0013] In one optional embodiment, the demagnetization method includes at least one of an electromagnetic separator, a permanent magnet separator, and a pipeline demagnetization device.
[0014] Secondly, the present invention also provides a modified ultra-high nickel cathode material prepared by the above-described preparation method.
[0015] Thirdly, the present invention also provides a positive electrode sheet of the above-mentioned modified ultra-high nickel positive electrode material.
[0016] Fourthly, the present invention also provides a lithium-ion battery comprising the above-described modified ultra-high nickel cathode material.
[0017] Those skilled in the art will understand that the lithium-ion battery provided by the present invention may include structural components such as an electrolyte, a positive electrode, a negative electrode, a separator, and a casing. During the charging and discharging process, lithium ions repeatedly insert and extract between the positive and negative electrode. The electrolyte acts as a conductor between the positive and negative electrode. The separator is disposed between the positive and negative electrode, primarily to prevent short circuits between the positive and negative electrodes, while simultaneously allowing lithium ions to pass through.
[0018] As an example, the positive electrode sheet includes a positive current collector and a positive active layer. The positive current collector has two opposing surfaces in its own thickness direction, and the positive active layer is disposed on either or both of the opposing surfaces of the positive current collector. The material of the positive electrode sheet used in the lithium-ion battery of the present invention is a modified ultra-high nickel positive electrode material prepared by the preparation method provided by the present invention.
[0019] As an example, the negative electrode sheet includes a negative electrode current collector and a negative electrode active layer. The negative electrode current collector has two opposing surfaces in its own thickness direction, and the negative electrode active layer is disposed on either or both of the opposing surfaces of the negative electrode current collector. The materials, composition, and manufacturing methods of the negative electrode sheet used in the lithium-ion battery of the present invention may include any techniques disclosed in the prior art.
[0020] The material and shape of the separator used in the lithium-ion battery of the present invention are not particularly limited, and may include any technology disclosed in the prior art.
[0021] The electrolyte used in the lithium-ion battery of the present invention may also include any technology disclosed in the prior art.
[0022] This invention does not specifically limit the preparation method of lithium-ion batteries; lithium-ion batteries can be prepared using conventional preparation methods in the art. For example, positive electrode sheets, separators, and negative electrode sheets are stacked sequentially, with the separator located between the positive and negative electrode sheets. A cell is obtained through stacking or winding processes, and then the lithium-ion battery of this invention is obtained through baking, electrolyte injection, formation, and packaging.
[0023] Fifthly, the present invention provides an electrical device comprising the above-described lithium-ion battery.
[0024] It is understood that in the electrical equipment provided by the present invention, the lithium-ion battery can be used as a power source for the electrical equipment, or as an energy storage unit for the electrical equipment. The electrical equipment may be, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
[0025] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention provides a method for preparing a modified ultra-high nickel cathode material. Through rapid heating at 10-20℃ / min and short-time two-stage sintering (first stage 0.5-2h, second stage 1-5h), combined with doping modification, the residence time of the material in the temperature range where residual alkali is easily generated can be shortened. This allows the residual alkali reduction process to be completed simultaneously during the lithiation sintering stage, significantly reducing residual alkaline substances (such as LiOH, Li2CO3) on the surface of the ultra-high nickel cathode material, inhibiting lithium-nickel mixing and stabilizing the layered crystal structure. This not only effectively maintains the discharge specific capacity, rate performance, and cycle stability of the material while reducing residual alkali, but also reduces water washing, acid washing, or complex post-processing steps, and reduces lithium loss, surface structure damage, and secondary heat treatment requirements that may be caused by the washing process, achieving synergistic optimization of material processing performance and electrochemical performance.
[0026] 2. The present invention provides a method for preparing a modified ultra-high nickel cathode material, wherein the dopant includes at least one of Al2O3, Al(OH)3, Al2(SO4)3, and Al(NO3)3. The Al element in the dopant can achieve stabilization and regulation of the lattice and surface of the ultra-high nickel cathode material, thereby enhancing the structural stability of the material. The amount of the dopant added accounts for 0.5-2 mol% of the total molar amount of transition metals in the ultra-high nickel ternary precursor, which can improve cycle performance while maintaining specific capacity. Attached Figure Description
[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0028] Figure 1 This is a SEM image of the modified ultra-high nickel cathode material prepared in Example 1 of this invention; Figure 2 This is a SEM image of the modified ultra-high nickel cathode material prepared in Comparative Example 1 of this invention. Detailed Implementation
[0029] 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.
[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having” and any variations thereof in the text of this application are intended to cover non-exclusive inclusion.
[0031] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers from a to b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed herein, and "0-5" is merely a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥ 2, it is equivalent to disclosing that the parameter can be, for example, integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
[0032] In the description of the embodiments of this application, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.
[0033] In the description of the embodiments of this application, the term "at least one" refers to one or more (including two).
[0034] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.
[0035] 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.
[0036] Example 1 This embodiment provides a modified ultra-high nickel cathode material, and the specific steps and operating parameters are as follows: S1 will use ultra-high nickel ternary precursors (Ni 0.96 Co 0.02 Mn 0.02 Lithium (OH)₂, lithium source (LiOH·H₂O), and dopant (Al(OH)₃) are mixed evenly in a high-speed mixer to obtain a mixture; the molar ratio of Li to Me in the lithium source and ultra-high nickel ternary precursor is 1.03:1; the amount of dopant added is 1 mol% of the total molar amount of Me in the ultra-high nickel ternary precursor. S2, the mixture is placed in an oxygen atmosphere furnace (oxygen volume fraction of 99.9%), and the temperature is increased from room temperature to 550℃ at a rate of 10℃ / min for the first sintering, and held for 1.5h. Then, the temperature is increased to 735℃ at a rate of 10℃ / min for the second sintering, and held for 5h. After sintering, the mixture is cooled to room temperature in an oxygen atmosphere (oxygen volume fraction of 99.8%). After crushing and sieving, the mixture is demagnetized twice using a pipeline demagnetizing device under a magnetic field strength of 10000Gs to obtain the modified ultra-high nickel cathode material with D50=5μm.
[0037] Example 2 This embodiment provides a modified ultra-high nickel cathode material, and the specific steps and operating parameters are as follows: S1 will use ultra-high nickel ternary precursors (Ni 0.92 Co 0.05 Al 0.03(OH)2), lithium source (LiOH·H2O), and dopant (Al2O3) are mixed evenly in a high-speed mixer to obtain a mixture; the molar ratio of Li to Me in the lithium source and ultra-high nickel ternary precursor is 1.02:1; the amount of dopant added is 1.5 mol% of the total molar amount of Me in the ultra-high nickel ternary precursor. S2, the mixture is placed in an oxygen atmosphere furnace (oxygen volume fraction of 99.5%), and the temperature is increased from room temperature to 500℃ at a rate of 15℃ / min for the first sintering, and held for 1 hour. The temperature is then increased to 700℃ at a rate of 15℃ / min for the second sintering, and held for 3 hours. After sintering, the mixture is cooled to room temperature in an oxygen atmosphere (oxygen volume fraction of 99.0%). After crushing and sieving, the mixture is demagnetized twice using a pipeline demagnetizing device under a magnetic field strength of 11000Gs to obtain the modified ultra-high nickel cathode material with D50=5μm.
[0038] Example 3 This embodiment provides a modified ultra-high nickel cathode material, and the specific steps and operating parameters are as follows: S1 will use ultra-high nickel ternary precursors (Ni 0.90 Co 0.05 Al 0.05 (OH)2), lithium source (LiOH·H2O), and dopant (Al2O3) are mixed evenly in a high-speed mixer to obtain a mixture; the molar ratio of Li to Me in the lithium source and ultra-high nickel ternary precursor is 1:1; the amount of dopant added is 2 mol% of the total molar amount of Me in the ultra-high nickel ternary precursor. S2, the mixture is placed in an oxygen atmosphere furnace (oxygen volume fraction of 98.5%), and the temperature is increased from room temperature to 450℃ at a rate of 20℃ / min for the first sintering, and held for 2 hours. Then, the temperature is increased to 750℃ at a rate of 10℃ / min for the second sintering, and held for 1 hour. After sintering, the mixture is cooled to room temperature in the furnace under an oxygen atmosphere (oxygen volume fraction of 99.9%). After crushing and sieving, the mixture is demagnetized three times using a pipeline demagnetizing device under a magnetic field strength of 8000Gs to obtain the modified ultra-high nickel cathode material with D50=3μm.
[0039] Example 4 This embodiment provides a modified ultra-high nickel cathode material, and the specific steps and operating parameters are as follows: S1 will use ultra-high nickel ternary precursors (Ni 0.98 Co 0.01 Mn 0.01(OH)2), lithium source (LiOH·H2O), and dopant (Al2(SO4)3) are mixed evenly in a high-speed mixer to obtain a mixture; the molar ratio of Li to Me in the lithium source and ultra-high nickel ternary precursor is 1.05:1; the amount of dopant added is 0.5 mol% of the total molar amount of Me in the ultra-high nickel ternary precursor. S2, the mixture is placed in an oxygen atmosphere furnace (oxygen volume fraction of 99.9%), and the temperature is increased from room temperature to 600℃ at a rate of 10℃ / min for the first sintering, and held for 0.5h. Then, the temperature is increased to 680℃ at a rate of 20℃ / min for the second sintering, and held for 5h. After sintering, the mixture is cooled to room temperature in the furnace under an oxygen atmosphere (oxygen volume fraction of 98.5%). After crushing and sieving, the mixture is demagnetized once using a pipeline demagnetizing device under a magnetic field strength of 12000Gs to obtain the modified ultra-high nickel cathode material with D50=10μm.
[0040] Comparative Example 1 This comparative example provides a modified ultra-high nickel cathode material, which differs from Example 1 only in the refined control of the parameters in the two sintering stages in S2. The specific operation is as follows: In S2, the mixture is placed in an oxygen atmosphere furnace (oxygen volume fraction of 99.8%), and the temperature is increased from room temperature to 500℃ at a rate of 2℃ / min for the first sintering, and held for 5 hours. Then, the temperature is increased to 720℃ at a rate of 2℃ / min for the second sintering, and held for 15 hours. After sintering, the mixture is cooled to room temperature in the furnace under an oxygen atmosphere. After crushing and sieving, it is demagnetized twice using a pipeline demagnetizing device under a magnetic field strength of 10000Gs to obtain the modified ultra-high nickel cathode material with D50=5μm.
[0041] Comparative Example 2 This comparative example provides a modified ultra-high nickel cathode material, which differs from Example 4 only in that the parameters of the first sintering are lower than the range values. The specific operation is as follows: In S2, the temperature of the first sintering is 400℃, the heating rate is 8℃ / min, and the holding time is 0.2h.
[0042] Comparative Example 3 This comparative example provides a modified ultra-high nickel cathode material, which differs from Example 4 only in that the parameters of the first sintering are higher than the range values. The specific operation is as follows: In S2, the temperature of the first sintering is 650℃, the heating rate is 25℃ / min, and the holding time is 2.5h.
[0043] Comparative Example 4 This comparative example provides a modified ultra-high nickel cathode material, which differs from Example 4 only in that the parameters of the second sintering are lower than the range values. The specific operation is as follows: In S2, the second sintering temperature is 650℃, the heating rate is 8℃ / min, and the holding time is 0.5h.
[0044] Comparative Example 5 This comparative example provides a modified ultra-high nickel cathode material, which differs from Example 4 only in that the parameters of the second sintering are higher than the range values. The specific operation is as follows: In S2, the second sintering temperature is 800℃, the heating rate is 25℃ / min, and the holding time is 6h.
[0045] Comparative Example 6 This comparative example provides a modified ultra-high nickel cathode material. The only difference from Example 4 is the change of the dopant in S1. Specifically, Al2(SO4)3 in S1 is replaced with an equimolar amount of MgSO4.
[0046] Experimental Example 1 50g of the modified ultra-high nickel cathode material provided in each example and comparative example was weighed, dispersed in deionized water, stirred and soaked, and then filtered. The contents of LiOH and Li2CO3 were determined by acid-base titration, and the total alkali content was calculated. The specific test results are shown in Table 1. Table 1 Residual Alkali Test Data
[0047] As shown in Table 1, by precisely controlling the temperature, heating rate, and holding time of the two-stage sintering process, Examples 1-4 of this invention successfully controlled the total residual alkali content of the ultra-high nickel cathode material to below 0.90%, which is significantly better than all comparative examples (>0.93%). Key comparative analysis shows that whether the sintering parameters of the first or second stage are below or above the limit range (as in Comparative Examples 2-5), the residual alkali content will increase sharply due to insufficient lithiation reaction or over-sintering. At the same time, the effect of the specific Al dopant (Example 4) is better than that of Mg dopant (Comparative Example 6). Furthermore, the rapid heating and short-time sintering strategy of this invention is more effective in suppressing surface side reactions than the traditional slow sintering process (Comparative Example 1). This fully demonstrates the core technical advantages of this two-stage refined sintering process in reducing residual alkali and improving material purity.
[0048] Experiment Example 2 The modified ultra-high nickel cathode materials provided in the various embodiments and comparative examples were applied to lithium-ion batteries, and then their electrical performance was tested.
[0049] The method for preparing the lithium-ion battery includes the following steps: The modified ultra-high nickel cathode material prepared in the above embodiments or comparative examples was used as the cathode active material and mixed with polyvinylidene fluoride and carbon black in a mass ratio of 95:2.5:2.5 to form a slurry, which was then coated. The compacted density of the electrode sheet was 3.2 g / cm³. 3 The obtained electrode sheet was used as the positive electrode, a lithium metal sheet as the counter electrode, and glass fiber as the separator. A 1 mol / L lithium hexafluorophosphate solution of ethylene carbonate (EC) and dimethyl carbonate (DMC) (EC to DMC volume ratio of 1:1) was used as the electrolyte. The cells were assembled into CR2032 coin cells in an argon-filled glove box. Finally, the cells were placed in the Blue Electric testing system for electrical performance testing.
[0050] The specific method for the electrical performance test is as follows: (1) First charge and discharge performance test At 25°C, the initial charging capacity is defined as the capacity obtained by constant charging at 0.2C until the voltage reaches 4.25V, and the initial discharge capacity is defined as the capacity obtained by constant discharging at 0.2C until the cutoff voltage reaches 2.5V. The discharge specific capacity (mAh / g) is calculated as follows: ; Where D1 is the initial discharge capacity (mAh) at a specified rate (e.g., 1C). m is the mass (g) of the active material (i.e., the modified ultra-high nickel cathode material) in the cathode sheet.
[0051] (2) Cyclic stability test The assembled coin cell was charged at a constant current of 1C to 4.25V, and then discharged at a constant current of 1C until the cutoff voltage of 2.5V was reached. This charge-discharge cycle was repeated 50 times. The discharge specific capacity and cycle capacity retention rate of the battery after 50 cycles were calculated. The cycle capacity retention rate (%) was calculated as follows: .
[0052] The specific test results are shown in the table below: Table 2 Electrical performance test data
[0053] Table 2 shows that the cycle stability of the ultra-high nickel cathode materials prepared in Examples 1-4 of this invention is significantly better than that of all comparative examples. The ultra-high nickel cathode material prepared in Example 1 exhibits the best long-term cycle performance while maintaining high initial capacity, while the cycle retention rate of Comparative Example 1 is significantly worse than that of Example 1 due to the use of a traditional slow-sintering process. Comparing with Example 4 as a benchmark, both Comparative Example 2 (low first-stage sintering parameters) and Comparative Example 3 (high first-stage sintering parameters) result in a reduction in the cycle life of the ultra-high nickel cathode material. The damage is particularly severe in Comparative Example 4 (insufficient second-stage sintering temperature), while Comparative Example 5 (excessively high second-stage sintering temperature) also leads to a decrease in material stability. Furthermore, after replacing the aluminum doping in Example 4 with magnesium doping in Comparative Example 6, the cycle retention rate of the resulting ultra-high nickel cathode material shows a sharp decline compared to Example 4. The electrochemical performance is significantly negatively correlated with the residual alkali content, confirming that this invention significantly improves the cycle stability of the material while ensuring high capacity through two-stage refined sintering and the synergistic effect of specific doping.
[0054] Figure 1 This is a SEM image of the modified ultra-high nickel cathode material prepared in Example 1 of this invention. Figure 1 It can be seen that the surface of the ultra-high nickel cathode material particles prepared in Example 1 is relatively clean, and no obvious residual alkali crystals or agglomerates are observed, indicating that the residual alkali content on the surface of the material is low.
[0055] Figure 2 This is a SEM image of the modified ultra-high nickel cathode material prepared in Comparative Example 1 of this invention. Figure 2 It can be seen that the ultra-high nickel cathode material prepared in Comparative Example 1 has a lot of residual alkali deposits on its surface, and some particles have obvious flaky or blocky residues on their surface, indicating that the material has a high residual alkali content.
[0056] 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 modified ultra-high nickel cathode material, characterized in that, Includes the following steps: S1, mix the ultra-high nickel ternary precursor, lithium source and dopant to obtain a mixture; The dopant includes Al-containing compounds; S2, the mixture is subjected to a first sintering, a second sintering, cooling, crushing, and demagnetizing to obtain the modified ultra-high nickel cathode material; The first sintering temperature is 450-600℃, the heating rate is 10-20℃ / min, and the holding time is 0.5-2h; The second sintering temperature is 680-750℃, the heating rate is 10-20℃ / min, and the holding time is 1-5h.
2. The preparation method according to claim 1, characterized in that, The amount of the dopant added accounts for 0.5-2 mol% of the total molar amount of transition metal in the ultra-high nickel ternary precursor; And / or, the general chemical formula of the ultra-high nickel ternary precursor is Ni x Co y A z (OH)2, wherein 0.90≤x≤0.98, 0.01≤y≤0.05, 0.01≤z≤0.05, x+y+z=1, and A is at least one of Mn and Al; And / or, the D50 of the modified ultra-high nickel cathode material is 3-10 μm.
3. The preparation method according to claim 1 or 2, characterized in that, The ratio of the total molar number of Li in the lithium source to the total molar number of transition metals in the ultra-high nickel ternary precursor is (1.00-1.05):
1.
4. The preparation method according to any one of claims 1-3, characterized in that, The dopant includes at least one of aluminum oxide, aluminum hydroxide, and aluminum salts; Optionally, the aluminum salt includes at least one of aluminum sulfate and aluminum nitrate; And / or, the lithium source includes at least one of lithium hydroxide and lithium carbonate.
5. The preparation method according to any one of claims 1-4, characterized in that, The atmosphere for the first sintering, the second sintering, and the cooling is independently an oxygen atmosphere; Optionally, the oxygen volume fraction of the oxygen atmosphere is 98.5% to 99.9%.
6. The preparation method according to any one of claims 1-5, characterized in that, The magnetic field strength for demagnetization is 8000–12000 Gs; And / or, the number of times the demagnetization is performed is 1 to 3.
7. A modified ultra-high nickel cathode material prepared by the preparation method according to any one of claims 1-6.
8. A positive electrode sheet, characterized in that, The material comprises the modified ultra-high nickel cathode material as described in claim 7.
9. A lithium-ion battery, characterized in that, It includes the positive electrode sheet as described in claim 8.
10. An electrical appliance, characterized in that, It includes the lithium-ion battery as described in claim 9.