Methods for Residual Alkali Removal in the Preparation Process of Ultra-High Nickel Ternary Cathode Materials and Their Applications

Abstract

This invention provides a method for removing residual alkali during the preparation of ultra-high nickel ternary cathode materials and its application. The method includes: sintering a first mixture containing an ultra-high nickel precursor material and a lithium source under an oxygen-containing atmosphere to obtain a first intermediate material; and then, under an inert atmosphere, fully contacting the first intermediate material with a fluoride plasma activation gas to allow lithium ions on the surface of the first intermediate material to react with the fluoride plasma activation gas, thereby obtaining a second intermediate material. The method provided by this invention utilizes the reaction between the fluoride plasma activation gas and the lithium ions on the surface of the first intermediate material. + The reaction produces LiF, avoiding Li + It reacts with H2O, CO2, etc. to produce LiOH and Li2CO3, achieving waterless washing to reduce residual alkali and solving the problem that the existing water washing process damages the material structure and leads to performance degradation.

Description

Technical Field

[0001] This invention belongs to the field of new energy technology, specifically relating to a method for removing residual alkali in the preparation process of ultra-high nickel ternary cathode materials and its application. Background Technology

[0002] Lithium-ion batteries, as a novel energy storage device, have attracted widespread attention due to their high energy density, low self-discharge, wide operating temperature range, and environmental friendliness. The demand for advanced energy storage systems with high energy density, long lifespan, and safety is becoming increasingly urgent. With the widespread application of lithium-ion batteries, higher requirements are being placed on the cathode materials used in these systems. Driven by market demand, mainstream high-nickel products are gradually evolving from Ni8 series to ultra-high nickel Ni90 and above (Ni content above 0.90%) series products. The research and development and production of ultra-high nickel series products has become one of the key areas of focus for the industry.

[0003] In some existing methods for preparing ultra-high nickel ternary cathode materials, pyrometallurgical sintering is typically required to form a primary sintered material. During the sintering process, due to the Li... + Migration and Li + / Ni 2+ Mixed discharge results in high residual alkali levels. Existing methods for removing residual alkali employ water washing, but this process damages the material structure, leading to decreased cycle performance, thermal stability, and rate capability. Therefore, providing a waterless residual alkali removal process suitable for the preparation of ultra-high nickel ternary cathode materials is one of the urgent problems to be solved in this field. Summary of the Invention

[0004] To solve all or part of the above-mentioned technical problems, the present invention provides the following technical solutions: The first aspect of this invention provides a method for removing residual alkali during the preparation process of ultra-high nickel ternary cathode materials, comprising: Under oxygen-containing atmosphere conditions, a first mixture containing ultra-high nickel precursor material and lithium source is sintered to obtain a first intermediate material; Under inert atmosphere conditions, the first intermediate material is brought into full contact with fluoride plasma activation gas, allowing lithium ions on the surface of the first intermediate material to react with the fluoride plasma activation gas, thereby obtaining the second intermediate material.

[0005] The method provided by this invention utilizes fluoride plasma activation gas and Li on the surface of the first intermediate material. + The reaction produces LiF, avoiding Li + It reacts with H2O, CO2, etc. to produce LiOH and Li2CO3, achieving waterless washing to reduce residual alkali and solving the problem that the water washing process in the existing technology damages the material structure and leads to performance degradation.

[0006] In some embodiments, the fluoride plasma activation gas is generated by applying periodic discharge-shutdown to the fluoride in a plasma reactor. This periodic discharge-shutdown process allows the fluoride in the generated plasma activation gas to fully react with the residual alkali on the material surface.

[0007] In some embodiments, within a "discharge-power-off" cycle, the discharge time is 5-15 minutes, preferably 8-12 minutes; the power-off time is 8-12 minutes. If the discharge time is too short, the removal of residual alkali will be ineffective, and excessively frequent charging / power-off will cause fluoride to accumulate on the surface, resulting in micro-uniformity; if the discharge time is too long, the Li on the surface will... + The excessive thickness of LiF formed by the reaction with fluoride plasma-activated gas on the material surface leads to an increase in internal resistance and a decrease in electrical performance.

[0008] In some embodiments, the metal cation in the fluoride is trivalent, and preferably, the fluoride includes AlF3 and / or LaF3.

[0009] In some embodiments, the method specifically includes: placing a first intermediate material in a plasma reactor under an inert atmosphere, and setting the plasma reactor to a periodic discharge-power-off operation mode, wherein the discharge time in one cycle is 8 min-12 min and the power-off time is 8 min-12 min; during the discharge phase, the fluoride is converted into the fluoride plasma activation gas; and the first intermediate material is agitated to allow it to fully contact the fluoride plasma activation gas for 10 min-20 min to react.

[0010] In some embodiments, the ultra-high nickel precursor material is an ultra-high nickel precursor material coated with a solid electrolyte.

[0011] In some embodiments, the ultra-high nickel precursor material coated with the solid electrolyte is prepared by a wet in-situ coating method.

[0012] In some embodiments, the preparation method of the solid electrolyte-coated ultra-high nickel precursor material includes: reacting a mixture containing a solid electrolyte, a surfactant, an ultra-high nickel ternary precursor, and a solvent at room temperature for 20-60 minutes to obtain the solid electrolyte-coated ultra-high nickel precursor material. This invention employs a wet in-situ coating method to coat a solid electrolyte onto an ultra-high nickel ternary precursor, followed by the addition of lithium salts and pyrometallurgical sintering. The solid electrolyte is further embedded into a layered structure and cured at high temperature. Compared to existing solid-phase mixing processes, the wet in-situ coating method allows for uniform coating of the solid electrolyte onto the surface of the ultra-high nickel ternary precursor, solving the problem of material electrical performance degradation caused by inhomogeneity in solid-phase mixing processes.

[0013] In-situ wet coating and waterless washing process for removing residual alkali improve the uniformity of element distribution and structural stability. The solid electrolyte also improves the conductivity of the material. Based on this, the electrochemical performance of the ultra-high nickel ternary cathode material is significantly improved.

[0014] In some embodiments, the content of solid electrolyte in the mixture is 0.10wt% to 0.30wt% of the ultra-high nickel ternary precursor. If too much solid electrolyte is added, it will lead to an increase in the coating thickness, with limited improvement in electrical performance.

[0015] In some embodiments, the surfactant content in the mixture is 45%-55% of the mixture volume.

[0016] In some embodiments, the chemical formula of the ultra-high nickel ternary precursor is Ni. x Co y Mn 1-x-y (OH)2, where 0.90≦x≦0.95 and 0.02≦y≦0.06.

[0017] In some embodiments, the surfactant includes at least one of KH550, KH560, and KH570. Adding a surfactant to the mixture helps reduce the surface tension between the solution and solid particles, aiding in the dispersion of solid electrolyte particles and thus achieving uniform solid-liquid mixing.

[0018] In some embodiments, the solid electrolyte includes at least one of LATP, LWTP, and LLZO.

[0019] In some embodiments, the solvent may include, for example, anhydrous ethanol and / or acetone, but is not limited thereto.

[0020] In some embodiments, after the reaction is completed, the obtained solid electrolyte-coated ultra-high nickel precursor material is heat-treated at 150℃-200℃ for 3h-5h to remove residual solvent and surfactant.

[0021] In some embodiments, the molar ratio of ultra-high nickel precursor material to lithium source in the first mixture is 1.03-1.05:1.

[0022] In some embodiments, the sintering process involves a first sintering stage and a second sintering stage. The temperature of the first sintering stage is 420-500℃, and the holding time is 1-3 hours. The temperature of the second sintering stage is 770℃-820℃, and the holding time is 8-12 hours.

[0023] In some embodiments, the sintering process uses a heating rate of 1 min / ℃ to 7 min / ℃.

[0024] In some embodiments, the lithium source includes lithium hydroxide.

[0025] A second aspect of the present invention provides a method for preparing an ultra-high nickel ternary cathode material, comprising: The second intermediate material is prepared by the residual alkali removal method in the preparation process of ultra-high nickel ternary cathode material according to any of the above technical solutions; By coating the second intermediate material with a boron-containing substance, an ultra-high nickel ternary cathode material is obtained.

[0026] In some embodiments, coating the second intermediate material with a boron-containing substance specifically includes reacting a second mixture containing the boron-containing substance and the second intermediate material at 300°C-350°C for 5-7 hours.

[0027] In some embodiments, the temperature is increased from room temperature to 300°C-350°C at a heating rate of 1-5 min / °C.

[0028] In some embodiments, the boron-containing substance includes boric acid and / or boron oxide.

[0029] In some embodiments, the amount of the boron-containing substance is 800ppm-1500ppm of the second intermediate material.

[0030] A third aspect of the present invention provides an ultra-high nickel ternary cathode material, which is prepared by the preparation method of the ultra-high nickel ternary cathode material described in any of the technical solutions.

[0031] A fourth aspect of the present invention provides a positive electrode for lithium-ion batteries, comprising the ultra-high nickel ternary positive electrode material described in any of the technical solutions.

[0032] A fifth aspect of the present invention provides a lithium-ion battery, wherein the positive electrode is the positive electrode for the lithium-ion battery described above.

[0033] Compared with the prior art, the present invention has at least the following beneficial effects: The method provided by the present invention utilizes the fluoride plasma activation gas and the Li on the surface of the first intermediate material obtained during the preparation of ultra-high nickel ternary cathode material. + The reaction produces LiF, avoiding Li + It reacts with H2O, CO2, etc. to produce LiOH and Li2CO3, achieving waterless washing to reduce residual alkali and solving the problem that the water washing process in the existing technology damages the material structure and leads to performance degradation. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1a , Figure 1b All are SEM images of the first intermediate material prepared in Example 1 of this invention; Figure 2a , Figure 2b This is a SEM image of the ultra-high nickel ternary cathode material finally obtained in Example 1 of this invention; Figure 3a , Figure 3b This is a SEM image of the ultra-high nickel ternary cathode material prepared in Comparative Example 2; Figure 4 These are the XRD patterns of the ultra-high nickel ternary cathode materials prepared in Example 1 and Comparative Example 2. Detailed Implementation

[0036] The invention will be more fully understood through the following detailed description, which should be read in conjunction with the accompanying drawings. Detailed embodiments of the invention are disclosed herein; however, it should be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, the specific functional details disclosed herein should not be construed as limiting, but rather as the basis for the claims and as intended to teach those skilled in the art to employ the representative basis of the invention in different ways in any suitable detailed embodiment.

[0037] In addition, unless otherwise specified, all raw materials used in the following embodiments can be purchased from the market or other sources, and all production and testing equipment used are known in the art, as are the testing methods used.

[0038] Example 1 This embodiment provides an ultra-high nickel ternary cathode material and its preparation method, specifically including the following steps: (1) Mix anhydrous ethanol and surfactant KH550 at a volume ratio of 1:1 for 10 min, and add ultra-high nickel ternary precursor (chemical formula Ni 0.92 Co 0.04 Mn 0.04 (OH)2) and solid electrolyte LATP were added to the above uniformly mixed anhydrous ethanol and KH550 to obtain a mixed reaction solution; the amount of LATP was 0.2wt% of the nickel content of the ultra-high nickel ternary precursor, and the surfactant accounted for 50% of the volume of the mixed reaction solution. The mixed reaction solution was stirred thoroughly at 25°C for 30 min, and then solid-liquid separation was performed to obtain the precursor material coated with solid electrolyte. Then, it was heat-treated at 180°C for 4 h to remove residual anhydrous ethanol and surfactant.

[0039] (2) The precursor material coated with solid electrolyte prepared above is mixed with lithium hydroxide at a molar ratio of 1.04:1. Under an oxygen-rich atmosphere, the temperature is increased from room temperature to 450°C at a heating rate of 3 min / °C and held for 2 h. Then, the temperature is increased to 800°C at a heating rate of 3 min / °C and held for 10 h. After the holding time is reached, the temperature is lowered to obtain the first intermediate material.

[0040] (3) Under a nitrogen protective atmosphere, the first intermediate material is placed in a plasma reactor, and the plasma reactor is set to a cycle operation mode of "discharge 10 min - power off 10 min". During the discharge stage, the fluoride AlF3 is converted into an active gas of plasma, and the first intermediate material is agitated and mixed, so that the Li on the surface of the first intermediate material is... + The material reacts with AlF3 plasma-activated gas to generate LiF, yielding the second intermediate material.

[0041] (4) The second intermediate material obtained by step (3) is mixed with boric acid to obtain a mixture. The amount of boric acid is 1000 ppm of the second intermediate material. The temperature is increased from room temperature to 320℃ at a heating rate of 3 min / ℃ and kept at 320℃ for 6 h. Then the temperature is reduced and the mixture is collected to obtain the ultra-high nickel ternary cathode material.

[0042] Example 2 Example 2 is basically the same as Example 1, except that in step (1) of Example 2, the amount of LATP used is 0.1 wt% of the content of ultra-high nickel ternary nickel cobalt manganese oxide. The rest is the same as in Example 1, and will not be repeated here.

[0043] Example 3 Example 3 is basically the same as Example 1, except that in step (1) of Example 3, the amount of LATP used is 0.3 wt% of the content of ultra-high nickel ternary nickel cobalt manganese oxide. The rest is the same as in Example 1, and will not be repeated here.

[0044] Example 4 Example 4 is basically the same as Example 1, except that in step (1) of Example 4, a precursor material coated with a solid electrolyte is obtained, and then heat-treated at 150°C for 4 hours to remove residual anhydrous ethanol and surfactant. The rest is the same as in Example 1, and will not be repeated here.

[0045] Example 5 Example 5 is basically the same as Example 1, except that in step (1) of Example 4, a precursor material coated with a solid electrolyte is obtained, and then heat-treated at 200°C for 4 hours to remove residual anhydrous ethanol and surfactant. The rest is the same as in Example 1, and will not be repeated here.

[0046] Example 6 Example 6 is basically the same as Example 1, except that in step (3) of Example 6, the plasma reactor operates in a cycle of "discharge 5 min - power outage 10 min".

[0047] Example 7 Example 7 is basically the same as Example 1, except that in step (3) of Example 7, the plasma reactor operates in a cycle of "discharge 15 min - power outage 10 min".

[0048] Example 8 Example 8 is basically the same as Example 1. In step (3) of Example 8, LaF3 is used instead of AlF3, that is, LaF3 is converted into LaF3 plasma activation gas by discharge in a plasma reactor. The rest is the same as in Example 1, and will not be repeated here.

[0049] Example 9 Example 9 is basically the same as Example 1, except that in step (3) of Example 9, the plasma reactor operates in a cycle of "discharge 8 min - power off 8 min". The rest is the same as in Example 1, and will not be described again here.

[0050] Example 10 Example 10 is basically the same as Example 1, except that in step (3) of Example 10, the plasma reactor operates in a cycle of "discharge 12 min - power outage 12 min". The rest is the same as in Example 1, and will not be described again here.

[0051] Example 11 Example 11 is basically the same as Example 1, except that in step (2) of Example 11, the temperature is increased from room temperature to 420°C at a heating rate of 1 min / °C and held for 1 h, then increased to 770°C at a heating rate of 1 min / °C and held for 8 h, and then cooled down after reaching the holding time to obtain the first intermediate material. The rest is the same as in Example 1, and will not be repeated here.

[0052] Example 12 Example 12 is basically the same as Example 1, except that in step (2) of Example 12, the temperature is increased from room temperature to 500°C at a heating rate of 7 min / °C and held for 3 h, then increased to 820°C at a heating rate of 7 min / °C and held for 12 h, and then cooled down after the holding time is reached to obtain the first intermediate material. The rest is the same as in Example 1, and will not be described again here.

[0053] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that step (3) of Comparative Example 1 uses a water washing process to remove residual alkali. Specifically, it includes: taking pure water at a temperature of 5-10℃ and mixing it with the first intermediate material at a water-to-material mass ratio of 1:2 for 2 minutes, then performing solid-liquid separation, and finally drying it in a vacuum drying oven to obtain the second intermediate material. The rest is the same as in Example 1 and will not be described again here.

[0054] Comparative Example 2 Comparative Example 2 provides a method for preparing ultra-high nickel ternary cathode materials using a dry solid-phase mixing process and a water washing process, specifically including: (1) Mix the ultra-high nickel ternary precursor, lithium hydroxide and solid electrolyte LATP in the same stoichiometric ratio as in Example 1. Under an oxygen-rich atmosphere, heat the resulting solid mixture from room temperature to 450°C at a heating rate of 3 min / °C and hold for 2 h. Then heat it to 800°C at a heating rate of 3 min / °C and hold for 10 h. After reaching the holding time, cool it down to obtain the first intermediate material.

[0055] (2) Washing the first intermediate material with water, specifically including: taking pure water at a temperature of 5-10℃ and mixing the first intermediate material with water at a mass ratio of 1:2 for 2 minutes, then separating the solid and liquid, and then drying it in a vacuum drying oven to obtain the second intermediate material.

[0056] (3) The second intermediate material obtained by washing with water is mixed with boric acid to obtain a mixture. The amount of boric acid is 1000 ppm of the second intermediate material. The temperature is increased from room temperature to 320℃ at a heating rate of 3 min / ℃ and kept at 320℃ for 6 h. The mixture is then cooled and collected to obtain an ultra-high nickel ternary cathode material.

[0057] The ultra-high nickel ternary cathode material obtained in the above embodiments and comparative examples is used to prepare cathode sheets, including: slurry preparation, coating, drying, rolling, and stamping processes. The above cathode sheets are then used to assemble coin cells. The coin cell assembly process is as follows: lithium-ion half-cell model CR2032; the assembly sequence is as follows: negative electrode shell, lithium sheet, electrolyte LiPF6, separator, cathode sheet based on the ultra-high nickel ternary cathode material of the embodiments and comparative examples, gasket, spring, and cathode shell.

[0058] The assembled battery was subjected to performance testing, and the testing method is as follows: (1) Capacity test: Under normal temperature conditions, the prepared battery was tested on a button cell battery test system. The charge and discharge voltage range was 2.8~4.25V. The capacity of the battery was tested at 0.1C charge and discharge.

[0059] (2) Rate performance test: Under normal temperature conditions, the prepared battery is tested on a button cell battery test system with a charge and discharge voltage range of 2.8~4.25V. The capacity during charge and discharge at 0.1C, 0.2C, 0.5C and 1C is measured.

[0060] (3) Cyclic performance test: Under normal temperature conditions, the prepared battery is tested on a button cell test system with a charge and discharge voltage range of 2.8~4.25V. The battery is cycled for 50 cycles at a current density of 1C to test the capacity retention rate.

[0061] The test results are summarized in Table 1.

[0062] Table 1. Battery performance based on ultra-high nickel ternary cathode materials in the examples and comparative examples.

[0063] Figure 1a , Figure 1b All images are SEM images of the first intermediate material prepared in Example 1 of this invention. The material has good sphericity, uniform particle size distribution, and good primary particle consistency. Figure 2a , Figure 2b These are all SEM images of the ultra-high nickel ternary cathode material finally obtained in Example 1 of this invention. The material prepared by AlF3 plasma activation gas treatment shows that the primary interparticle gaps or vacancies are well filled, and excess Li... + The reaction generates LiF, which fills the gaps. This waterless method for removing residual alkali is effective and improves the material's resistance to electrolyte corrosion and its cycle performance.

[0064] Figure 3a , Figure 3b The image shows a SEM image of the ultra-high nickel ternary cathode material prepared in Comparative Example 2. Figure 3a , Figure 3bIt is known that the coating on the surface of the prepared material has slight inhomogeneity and some exposed surfaces, especially with obvious voids. These voids not only have high residual alkali content, but are also susceptible to electrolyte corrosion, leading to structural collapse. Figure 4 These are the XRD patterns of the ultra-high nickel ternary cathode materials prepared in Example 1 and Comparative Example 2. The ratio of I(003) / I(104) for the material prepared in Example 1 is 2.46, and the ratio of I(003) / I(104) for the material prepared in Comparative Example 2 is 2.32. The higher the ratio, the more stable the layered structure.

[0065] As shown in Table 1, the high-nickel ternary cathode material prepared under the optimal conditions in Example 1 achieved an electrical capacity of 226.43 mAh / g. After 50 cycles at 1C, the capacity retention rate reached 96.9%, demonstrating high structural stability and superior electrochemical performance.

[0066] In Example 4, the conditions for removing residual anhydrous ethanol and surfactant were a low temperature of 150°C for 4 hours. Under this relatively low temperature, a slight residue of surfactant remained, leading to an increase in internal resistance and a slight decrease in electrical performance. In Example 5, the conditions for removing residual anhydrous ethanol and surfactant were 200°C for 4 hours. While this temperature was relatively high and effectively removed the surfactant, the high temperature also caused the loss of some hydroxyl groups on the precursor, resulting in lithium ligand shift and affecting electrical performance. Considering all factors, the optimal temperature for removing residual anhydrous ethanol and surfactant is 150°C to 200°C for 3 to 5 hours, preferably 180°C for 4 hours. This results in an ultra-high nickel ternary cathode material with good electrical performance within an acceptable range.

[0067] In Example 6, the plasma reactor operates in a cyclical mode of "5 min discharge - 10 min power outage". The shorter discharge time results in a relatively thinner fluoride thickness, a slight decrease in residual alkali reduction capacity, and slightly weaker electrical performance compared to Example 1. Example 7 uses a cyclical mode of "15 min discharge - 10 min power outage" for the plasma reactor. The extended discharge time leads to fluoride accumulation on the material surface and slight inhomogeneity, increasing internal resistance and slightly decreasing electrical performance. Considering all factors, a discharge time of 8-12 min and a power outage time of 8-12 min within a single cycle results in a suitable fluoride thickness, thus maintaining the electrical performance of the ultra-high nickel ternary cathode material within an acceptable range.

[0068] In Example 8, the fluoride used was LaF3. The electrical properties of the ultra-high nickel ternary cathode material prepared therefrom were basically equivalent to those in Example 1, indicating that trivalent fluorides all played a role in improving resistance to electrolyte corrosion. The performance of the ultra-high nickel ternary cathode materials prepared in Examples 9-12 was basically equivalent to that in Example 1, with only minor variations.

[0069] Comparative Example 1 uses a water washing process to remove residual alkali. Water washing has a certain damaging effect on the surface of the material, which reduces the material's resistance to electrolyte corrosion. At the same time, it produces Ni-O, an electrically inert substance in the rock salt phase, which leads to a decrease in electrical performance.

[0070] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0071] All aspects, embodiments, features, and examples of this invention should be considered illustrative and used to explain and illustrate the invention, but not to limit the invention. The scope of the invention is defined only by the claims.

[0072] Although the invention has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions can be made without departing from the spirit and scope of the invention, and that elements of the described embodiments can be substituted with substantially equivalents. Furthermore, many modifications can be made without departing from the scope of the invention to adapt particular situations or materials to the teachings of the invention. Therefore, this invention is not intended to be limited to the specific embodiments disclosed for carrying out the invention, but rather is intended to encompass all embodiments falling within the scope of the appended claims.

Claims

1. A method for removing residual alkali during the preparation of ultra-high nickel ternary cathode materials, characterized in that, include: Under oxygen-containing atmosphere conditions, a first mixture containing ultra-high nickel precursor material and lithium source is sintered to obtain a first intermediate material; Under inert atmosphere conditions, the first intermediate material is brought into full contact with fluoride plasma activation gas, allowing lithium ions on the surface of the first intermediate material to react with the fluoride plasma activation gas, thereby obtaining the second intermediate material.

2. The method for removing residual alkali during the preparation process of ultra-high nickel ternary cathode material according to claim 1, characterized in that: The fluoride plasma activation gas is generated by applying periodic discharge-shutdown to the fluoride in a plasma reactor; preferably, the discharge time is 8 min-12 min and the shutdown time is 8 min-12 min in one cycle. And / or, the metal cation in the fluoride is trivalent; And / or, the fluoride includes AlF3 and / or LaF3; And / or, the molar ratio of ultra-high nickel precursor material to lithium source in the first mixture is 1.03-1.05:1; And / or, the sintering process sequentially goes through a first sintering stage and a second sintering stage, wherein the temperature of the first sintering stage is 420℃-500℃ and the holding time is 1h-3h, and the temperature of the second sintering stage is 770℃-820℃ and the holding time is 8h-12h. And / or, the lithium source includes lithium hydroxide.

3. The method for removing residual alkali during the preparation process of ultra-high nickel ternary cathode material according to claim 1, characterized in that: The ultra-high nickel precursor material is an ultra-high nickel precursor material coated with a solid electrolyte.

4. The method for removing residual alkali during the preparation process of ultra-high nickel ternary cathode material according to claim 3, characterized in that, The preparation method of the solid electrolyte-coated ultra-high nickel precursor material includes: reacting a mixture containing a solid electrolyte, a surfactant, an ultra-high nickel ternary precursor and a solvent at room temperature for 20 min-60 min to obtain the solid electrolyte-coated ultra-high nickel precursor material.

5. The method for removing residual alkali during the preparation process of ultra-high nickel ternary cathode material according to claim 4, characterized in that: The content of solid electrolyte in the mixture is 0.10wt%~0.30wt% of the ultra-high nickel ternary precursor, and / or the content of surfactant in the mixture accounts for 45%-55% of the volume of the mixture; And / or, the chemical formula of the ultra-high nickel ternary precursor is Ni x Co y Mn 1-x-y (OH)2, where 0.90≦x≦0.95 and 0.02≦y≦0.06; And / or, the surfactant includes at least one of KH550, KH560, and KH570; And / or, the solid electrolyte includes at least one of LATP, LWTP, and LLZO; And / or, after the reaction is completed, the obtained solid electrolyte-coated ultra-high nickel precursor material is heat-treated at 150℃~200℃ for 3h~5h to remove residual solvent and surfactant.

6. A method for preparing an ultra-high nickel ternary cathode material, characterized in that, include: The second intermediate material is prepared by the method according to any one of claims 1-5; By coating the second intermediate material with a boron-containing substance, an ultra-high nickel ternary cathode material is obtained.

7. The method for preparing ultra-high nickel ternary cathode material according to claim 6, characterized in that, The coating of the second intermediate material with a boron-containing substance specifically includes: reacting a second mixture containing the boron-containing substance and the second intermediate material at 300℃-350℃ for 5h-7h; And / or, the boron-containing substance includes boric acid and / or boron oxide; And / or, the amount of the boron-containing substance used is 800ppm-1500ppm of the second intermediate material.

8. A high-nickel ternary cathode material, characterized in that, It is prepared by the method for preparing ultra-high nickel ternary cathode material according to any one of claims 6-7.

9. A positive electrode for a lithium-ion battery, characterized in that, Including the ultra-high nickel ternary cathode material as described in claim 8.

10. A lithium-ion battery, characterized in that, Its positive electrode is the positive electrode for the lithium-ion battery as described in claim 9.

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