A high-temperature single-crystal high-nickel cathode material, its preparation method and application

Abstract

This invention discloses a high-temperature single-crystal high-nickel cathode material, its preparation method, and its applications. The invention utilizes a coating agent to coat a single-crystal high-nickel precursor, which is then dried to obtain a coated precursor. A cobalt-aluminum co-doped modified single-crystal high-nickel cathode material is obtained after a single sintering process. A porphyrin-based microporous polymer layer and a polyurethane layer are then sequentially coated onto the surface of the modified single-crystal high-nickel cathode material. Finally, CO2 is absorbed and mineralized on the surface of the polyurethane layer, forming a porphyrin-based microporous polymer / polyurethane-calcium carbonate composite layer on the surface of the modified single-crystal high-nickel cathode material, thus creating the high-temperature single-crystal high-nickel cathode material. This high-temperature single-crystal high-nickel cathode material can reduce the gas production during high-temperature cycle charging and discharging of lithium-ion batteries prepared with it, solving the battery capacity degradation problem caused by edge lithium plating due to bubble accumulation inside the battery.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery cathode material technology, and relates to a high-temperature single-crystal high-nickel cathode material, its preparation method and application. Background Technology

[0002] Lithium-ion batteries are mainly composed of a positive electrode, a negative electrode, and an electrolyte. Most of the chemical reactions occur at the electrode / electrolyte interface, making the stability of the electrolyte at the electrode interface crucial to the overall stability of the lithium-ion battery. With the continuous improvement of lithium-ion battery energy density, the application of ternary materials, especially high-nickel single-crystal ternary materials, is becoming increasingly common. However, as the Ni content increases, the stability of the electrode interface also deteriorates, with the most common problem being gas generation during long-cycle operation at high cutoff voltages or during high-temperature storage.

[0003] Gas formation in lithium-ion batteries is an unavoidable issue during use. It typically results from the decomposition of impurities (such as LiOH and Li₂CO₃) on the surface of the positive electrode material under high voltage. High-temperature storage (≥60℃) also exacerbates gas formation. Gas buildup in lithium-ion batteries not only causes bubbles to accumulate inside the cell, leading to rapid expansion and leakage, but also results in lithium deposition at the bubble edges, causing a decrease in battery capacity.

[0004] Therefore, it is necessary to develop a high-temperature resistant cathode material to reduce the amount of gas generated in lithium-ion batteries during high-temperature cyclic charging and discharging, in order to solve the problems of rapid expansion of the battery body caused by bubble accumulation inside the cell, leading to leakage and battery capacity degradation. Summary of the Invention

[0005] The purpose of this invention is to provide a high-temperature single-crystal high-nickel cathode material, its preparation method, and its application. This high-temperature single-crystal high-nickel cathode material can reduce the gas production during high-temperature cyclic charging and discharging of lithium-ion batteries prepared from it, thus solving the problem of battery capacity degradation caused by edge lithium plating due to bubble accumulation inside the battery.

[0006] This invention discloses a method for preparing a high-temperature single-crystal high-nickel cathode material. First, a single-crystal high-nickel precursor is coated with a cobalt hydroxide and aluminum hydroxide composite layer. After drying, the coated precursor is obtained. After a single sintering, a cobalt-aluminum co-doped modified single-crystal high-nickel cathode material is obtained. Then, a porphyrin-based microporous polymer layer and a polyurethane layer are sequentially coated on the surface of the modified single-crystal high-nickel cathode material. Finally, after CO2 is absorbed and mineralized on the surface of the polyurethane layer, a porphyrin-based microporous polymer / polyurethane-calcium carbonate (PACMP / PU-CaCO3) composite layer is formed on the surface of the modified single-crystal high-nickel cathode material.

[0007] This invention provides a method for preparing a high-temperature single-crystal high-nickel cathode material, comprising the following steps:

[0008] 1) The coated single-crystal high-nickel cathode precursor was mixed with a lithium source and sintered. After crushing and sieving, the modified single-crystal high-nickel cathode material LiNi was obtained. x Co y T 1-x-y O2;

[0009] 2) The modified single-crystal high-nickel cathode material LiNi x Co y T 1-x-y O2, pyrrole, propionic acid and tetra(4-aldehyde)phenylsilane are mixed and reacted in nitrogen and / or an inert atmosphere to obtain porphyrin-based microporous polymer-coated modified single-crystal high-nickel cathode material.

[0010] 3) The monocrystalline high-nickel cathode material coated with diisocyanate and porphyrin-based microporous polymer is mixed and reacted, followed by the addition of diol and then N,N-dimethyl-N',N'-di(2-hydroxypropyl)-1,3-propanediamine and chain extender are added to continue the reaction. After the above reaction is completed, a salting agent is added for neutralization, and finally deionized water is added for high-speed emulsification to obtain a mixed slurry. The mixed slurry is spray-dried once to obtain polyurethane / porphyrin-based microporous polymer coated and modified monocrystalline high-nickel cathode material. Then, it is placed in a simulated mineralization solution for mineralization and spray-dried a second time to obtain porphyrin-based microporous polymer / polyurethane-calcium carbonate composite layer coated and modified monocrystalline high-nickel cathode material, which is the high-temperature monocrystalline high-nickel cathode material.

[0011] In the above method, step 1), preparing the single-crystal high-nickel cathode precursor coated with the coating agent includes the following steps: [The text abruptly shifts to a different topic] x Co y T 1-x-y (OH)2 is dispersed in deionized water and stirred to obtain a slurry; a coating agent is added to the slurry and the pH value is adjusted, and then the slurry is aged, filtered, washed and dried to obtain the coated single crystal high nickel cathode precursor;

[0012] The chemical formula of the single-crystal high-nickel cathode precursor is Ni. x Co y T 1-x-y (OH)2, where 0.7≤x<1, 0<y≤0.1, and T is Mn and / or Al.

[0013] In this invention, the washing process in preparing the coated single-crystal high-nickel cathode precursor involves washing with deionized water 3 to 5 times, and the drying process can be carried out at 100 to 200°C.

[0014] In the above method, the mass ratio of the single-crystal high-nickel cathode precursor, the coating agent, and the deionized water can be 1:0.1 to 0.26:3.2, specifically 1:0.1:3.2, 1:0.12:3.2, 1:0.18:3.2, 1:0.2:3.2, or 1:0.26:3.2.

[0015] The coating agent is prepared by mixing cobalt sulfate and aluminum sulfate in a mass ratio of 1:3 in a high-speed mixer for 25-60 minutes.

[0016] The stirring and mixing time can be 20 to 120 minutes, specifically 20 minutes, 60 minutes, or 120 minutes.

[0017] The pH value is adjusted to 9-11 using ammonia and / or sodium hydroxide, specifically 9, 9.4, 10, 10.5, or 11.

[0018] The aging temperature can be 40-60℃, specifically 40℃, 45℃, 47℃, 50℃, or 60℃, and the aging time can be 4-8 hours, specifically 4 hours, 4.5 hours, 5.6 hours, 6 hours, or 8 hours.

[0019] In the above method, the mass ratio of the coated single-crystal high-nickel cathode precursor to the lithium source in step 1) can be 2.01 to 2.32:1;

[0020] The lithium source is lithium hydroxide and / or lithium carbonate;

[0021] The sintering temperature can be 800-900℃, specifically 800℃, 840℃, 880℃, or 900℃, and the time can be 10-20h, specifically 10h, 13.5h, 15h, or 20h.

[0022] The modified single-crystal high-nickel cathode material LiNi x Co y T 1-x-y The median particle size of O2 can be 2–5 μm, specifically 2 μm, 2.65 μm, 3 μm, 4 μm, and 5 μm.

[0023] The modified single-crystal high-nickel cathode material LiNi x Co y T 1-x-y The specific surface area of ​​O2 can range from 0.55 to 0.95 m². 2 / g, specifically 0.55m 2 / g, 0.65m 2 / g, 0.72m 2 / g, 0.88m 2 / g, 0.95m 2 / g.

[0024] In the above method, in step 2), the modified single-crystal high-nickel cathode material LiNi x Co y T 1-x-y The mass ratio of O2, pyrrole, propionic acid, and tetra(4-aldehyde)phenylsilane can be 1:0.0006-0.0008:0.0004:0.1-0.26, specifically 1:0.0006:0.0004:0.1, 1:0.00062:0.0004:0.18, 1:0.00066:0.0004:0.24, 1:0.0008:0.0004:0.26, and 1:0.0008:0.0004:0.26.

[0025] The reaction temperature can be 120-150℃, specifically 120℃, 130℃, 132℃, or 135℃, and the reaction time can be 20-24h, specifically 20h, 22h, 22.2h, or 24h.

[0026] In the above method, step 2) further includes the steps of filtration, washing, and drying after the reaction is completed;

[0027] The post-filtration washing process is as follows: the filter cake is washed with deionized water 3 to 5 times, and then washed with N,N-dimethylformamide, dichloromethane, and tetrahydrofuran 3 to 5 times each in sequence.

[0028] The drying temperature can be 80-120℃, specifically 80℃, 96℃, 100℃, 110℃, or 120℃, and the drying time can be 6-12 hours, specifically 6 hours, 8 hours, 8.5 hours, 10 hours, or 12 hours.

[0029] In the above method, in step 3), the temperature of the mixing reaction can be 40-80℃, specifically 40℃, 48℃, 58℃, 62℃, or 80℃, and the time can be 1-4h, specifically 1h, 1.4h, 3.6h, or 4h.

[0030] The temperature of the reaction involving the addition of the diol can be 84–94°C, specifically 84°C, 86°C, 90°C, 92°C, or 94°C, and the time can be 4–8 hours, specifically 2.4 hours, 4 hours, 5.5 hours, 6 hours, 6.8 hours, or 8 hours.

[0031] The temperature at which N,N-dimethyl-N',N'-di(2-hydroxypropyl)-1,3-propanediamine is added can be 62–76°C, and the temperature at which it reacts with the chain extender can be 62–76°C, specifically 62°C, 68°C, 70°C, 72°C, or 76°C. The reaction time can be 3–6 hours, specifically 3 hours, 4.5 hours, 5 hours, 5.8 hours, or 6 hours.

[0032] The outlet temperature of the primary spray dryer can be 60-90℃, specifically 60℃, 75℃, 80℃, 85℃, 86℃, 88℃, or 90℃.

[0033] In the above method, the mass ratio of the porphyrin-based microporous polymer-coated modified single-crystal high-nickel cathode material, the diisocyanate, the diol, the N,N-dimethyl-N',N'-di(2-hydroxypropyl)-1,3-propanediamine, the chain extender, the salt-forming agent, and the deionized water can be 1000:2.9:4.7:0.41~0.62:0.77:0.25:0.8~1.4:2000, specifically 1000:2.9:4.7:0.41: 0.77:0.25:0.8:2000, 1000:2.9:4.7:0.55:0.77:0.25:0.96:2000, 1000:2.9:4.7:0.62:0.77:0.25:0.92:2000, 1000:2.9:4.7:0.62:0.77:0.25:1.4:2000, 1000:2.9:4.7:0.5:0.77:0.25:0.96:2000;

[0034] The diisocyanate is selected from at least one of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate;

[0035] The diol is selected from at least one of poly(1,6-hexanediol carbonate), polytetrahydrofuran ether diol, polyethylene glycol, polycaprolactone diol, and polypropylene oxide diol.

[0036] The chain extender is selected from 1,4-butanediol and / or diethylene glycol;

[0037] The salt-forming agent is selected from at least one of acetic acid, 3-carboxy-3-hydroxyglutaric acid, and 2,2-dihydroxymethylpropionic acid.

[0038] In the above method, the simulated mineralization solution is obtained by mixing deionized water, sodium chloride, sodium bicarbonate, and calcium chloride in a mass ratio of 1:0.02-0.026:0.012-0.02:0.008-0.011.

[0039] The mass ratio of the polyurethane / porphyrin-based microporous polymer-coated modified single-crystal high-nickel cathode material to the simulated mineralization solution can be 1:3 to 6, specifically 1:3, 1:4, 1:4.5, 1:5.2, or 1:6.

[0040] The mineralization time can be 18 to 24 hours, specifically 18 hours, 20 hours, 21.5 hours, or 24 hours; the mineralization temperature is room temperature, which is common knowledge in the field, and can specifically be 10 to 30°C.

[0041] The outlet temperature of the secondary spray drying can be 100-120℃, specifically 100℃, 105℃, 106℃, 110℃, 112℃, or 120℃, and the time can be 6-14h, specifically 6h, 8h, 12h, 12.5h, or 14h.

[0042] The present invention also provides a high-temperature single-crystal high-nickel cathode material prepared by the above-described preparation method.

[0043] The present invention further provides a lithium-ion battery, comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the positive electrode is made of the above-mentioned high-temperature single-crystal high-nickel positive electrode material.

[0044] The present invention has the following beneficial effects:

[0045] 1. This invention modifies the precursor by coating it with a coating agent, and obtains a cobalt-aluminum co-doped modified single-crystal high-nickel cathode material with a narrow median particle size and a high specific surface area after one-time sintering, crushing and sieving. The narrow median particle size distribution and high specific surface area are beneficial to improving the coating efficiency of the porphyrin-based microporous polymer / polyurethane-calcium carbonate (PACMP / PU-CaCO3) composite layer.

[0046] 2. A composite layer is used to coat and modify the modified single-crystal high-nickel cathode material. The porphyrin-based microporous polymer can effectively absorb CO2 generated by residual alkali on the surface of the cathode material under high temperature and long cycle, which effectively reduces the volume expansion rate of the prepared battery and solves the problems of edge lithium plating and battery capacity decay.

[0047] 3. The polyurethane-calcium carbonate layer in the composite layer can continuously adsorb byproducts of electrolyte decomposition and release substances containing LiPO2F2 and Ca. 2+ The active material effectively reduces the interfacial side reactions between the electrolyte and the positive electrode, inhibits the growth of lithium dendrites and the generation of alkane gases (C2H6, C2H4, CH4), and improves the cycle life of batteries made of positive electrode materials.

[0048] 4. The high-temperature single-crystal high-nickel cathode material provided by this invention, through the synergistic effect of cobalt-aluminum co-doping and porphyrin-based microporous polymer / polyurethane-calcium carbonate (PACMP / PU-CaCO3) composite layer, effectively reduces the gas generation and interfacial side reactions between the electrode and electrolyte during the high-temperature cycle charge-discharge process of the lithium-ion battery prepared by it, and solves the problems of edge lithium plating and battery capacity decay caused by bubble accumulation inside the battery. Attached Figure Description

[0049] Figure 1 This is a microscopic morphology diagram of the cathode material prepared in Example 1 of the present invention.

[0050] Figure 2 This is a microscopic morphology diagram of the cathode material prepared in Comparative Example 1 of this invention. Detailed Implementation

[0051] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0052] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0053] Example 1

[0054] A high-temperature single-crystal high-nickel cathode material is prepared by the following steps:

[0055] S1. Preparation of modified single-crystal high-nickel cathode material:

[0056] (1) Single-crystal high-nickel cathode precursor Ni 0.7 Co 0.05 Mn 0.25 (OH)₂ was dispersed in deionized water and stirred for 20 minutes to obtain a slurry. Cobalt sulfate and aluminum sulfate were then added to the slurry and mixed for 25 minutes in a high-speed mixer. Ammonia was added to adjust the pH to 9. The mixture was aged at 40°C for 4 hours, washed three times with deionized water, and dried at 100°C to obtain a cobalt hydroxide and aluminum hydroxide composite layer-coated single-crystal high-nickel cathode precursor. In the above preparation process, Ni… 0.7 Co 0.05 Mn 0.25 The mass ratio of (OH)2, cobalt sulfate, aluminum sulfate, and deionized water is 1:0.025:0.075:3.2.

[0057] (2) Coating the single-crystal high-nickel cathode precursor Ni with a cobalt hydroxide and aluminum hydroxide composite layer. 0.7 Co 0.05 Mn 0.25 (OH)₂ and lithium hydroxide were mixed at a mass ratio of 2.01:1 and sintered in a tube furnace at 800℃ for 10 hours. After pulverization and sieving, the resulting material had a median particle size of 2 μm and a specific surface area of ​​0.55 m². 2 / g modified single-crystal high-nickel cathode material LiNi 0.7 Co 0.05 Mn 0.25 O2.

[0058] S2, Preparation of single-crystal high-nickel cathode material coated with porphyrin-based microporous polymer:

[0059] The modified single-crystal high-nickel cathode material obtained in step S1, pyrrole, propionic acid, and tetra(4-aldehyde)phenylsilane were added to a reaction vessel after being magnetically stirred for 1 hour at a mass ratio of 1:0.0006:0.0004:0.1. The mixture was heated to 120℃ under nitrogen protection and reacted for 20 hours. After the reaction was completed, the mixture was filtered. The filter cake was washed three times with deionized water, and then washed three times each with N,N-dimethylformamide, dichloromethane, and tetrahydrofuran. Finally, it was dried at 80℃ for 6 hours to obtain the final product.

[0060] S3, Preparation of modified single-crystal high-nickel cathode material coated with porphyrin-based microporous polymer / polyurethane-calcium carbonate composite layer:

[0061] (1) Toluene diisocyanate and porphyrin-based microporous polymer-coated modified single-crystal high-nickel cathode material were added to a reaction vessel equipped with a stirrer and heated to 40°C for 1 hour. Then, 1,6-hexanediol polycarbonate was added and the temperature was raised to 84°C for 4 hours. After cooling to 62°C, N,N-dimethyl-N',N'-di(2-hydroxypropyl)-1,3-propanediamine and 1,4-butanediol were added and the reaction was continued for 3 hours. After the above reaction was completed, acetic acid was added for neutralization. Finally, deionized water and porphyrin-based microporous polymer-coated modified single-crystal cathode material were added. Slurry 1 was prepared by high-speed emulsification of high-nickel cathode material; slurry 1 was then spray-dried at an outlet temperature of 60℃. In the above preparation steps, the mass ratio of porphyrin-based microporous polymer-coated modified single-crystal high-nickel cathode material, toluene diisocyanate, polycarbonate 1,6-hexanediol diol, N,N-dimethyl-N',N'-di(2-hydroxypropyl)-1,3-propanediamine, 1,4-butanediol, acetic acid, and deionized water was 1000:2.9:4.7:0.41:0.77:0.25:0.8:2000.

[0062] (2) Then, a simulated mineralization solution was obtained by mixing deionized water, sodium chloride, sodium bicarbonate and calcium chloride in a mass ratio of 1:0.02:0.012:0.008. The porphyrin-based microporous polymer / polyurethane-coated modified single crystal high nickel cathode material was then placed in the simulated mineralization solution and mineralized at room temperature for 18 hours to obtain slurry 2. The slurry 2 was then spray-dried at an outlet temperature of 100℃. In the above preparation process, the mass ratio of porphyrin-based microporous polymer / polyurethane-coated modified single crystal high nickel cathode material to simulated mineralization solution was 1:3.

[0063] Example 2

[0064] A high-temperature single-crystal high-nickel cathode material is prepared by the following steps:

[0065] S1. Preparation of modified single-crystal high-nickel cathode material:

[0066] (1) Single-crystal high-nickel cathode precursor Ni 0.8 Co 0.1 Mn0.1 (OH)₂ was dispersed in deionized water and stirred for 40 min to obtain a slurry. Cobalt sulfate and aluminum sulfate were then added to the slurry and mixed for 45 min in a high-speed mixer. Ammonia was then added to adjust the pH to 10.5. The mixture was aged at 50°C for 6 h, washed five times with deionized water, and dried at 160°C to obtain a cobalt hydroxide and aluminum hydroxide composite layer-coated single-crystal high-nickel cathode precursor. In the above preparation process, Ni… 0.8 Co 0.1 Mn 0.1 The mass ratio of (OH)2, cobalt sulfate, aluminum sulfate, and deionized water is 1:0.05:0.15:3.2.

[0067] (2) Coating the single-crystal high-nickel cathode precursor Ni with a cobalt hydroxide and aluminum hydroxide composite layer. 0.8 Co 0.1 Mn 0.1 (OH)₂ and lithium hydroxide were mixed at a mass ratio of 2.22:1 and sintered in a tube furnace at 840℃ for 13.5 h. After crushing and sieving, the resulting particles had a median particle size of 4 μm and a specific surface area of ​​0.65 m². 2 / g modified single-crystal high-nickel cathode material LiNi 0.8 Co 0.1 Mn 0.1 O2.

[0068] S2, Preparation of single-crystal high-nickel cathode material coated with porphyrin-based microporous polymer:

[0069] The modified single-crystal high-nickel cathode material obtained in step S1, pyrrole, propionic acid, and tetra(4-aldehyde)phenylsilane were added to a reaction vessel after magnetic stirring for 2 hours at a mass ratio of 1:0.00062:0.0004:0.18. The mixture was heated to 135℃ under nitrogen protection and reacted for 22 hours. After the reaction was completed, the mixture was filtered. The filter cake was washed 5 times with deionized water, and then washed 4 times each with N,N-dimethylformamide, dichloromethane, and tetrahydrofuran. Finally, it was dried at 100℃ for 10 hours to obtain the final product.

[0070] S3, Preparation of modified single-crystal high-nickel cathode material coated with porphyrin-based microporous polymer / polyurethane-calcium carbonate composite layer:

[0071] (1) Diphenylmethane diisocyanate and porphyrin-based microporous polymer-coated modified single-crystal high-nickel cathode material were added to a reaction vessel equipped with a stirrer and heated to 48°C for 4 hours. Then, polytetrahydrofuran ether glycol was added and the temperature was raised to 90°C for 6 hours. After cooling to 72°C, N,N-dimethyl-N',N'-di(2-hydroxypropyl)-1,3-propanediamine and diethylene glycol were added and the reaction was continued for 5 hours. After the above reaction was completed, 3-carboxy-3-hydroxyglutaric acid was added for neutralization. Finally, deionized water and porphyrin-based microporous polymer-coated modified single-crystal high-nickel cathode material were added. Slurry 1 was prepared by high-speed emulsification of nickel cathode material; the slurry 1 was then spray-dried at an outlet temperature of 90℃ to obtain the final product; in the above preparation steps, the mass ratio of porphyrin-based microporous polymer-coated modified single-crystal high-nickel cathode material, diphenylmethane diisocyanate, polytetrahydrofuran ether diol, N,N-dimethyl-N',N'-di(2-hydroxypropyl)-1,3-propanediamine, diethylene glycol, 3-carboxy-3-hydroxyglutaric acid, and deionized water was 1000:2.9:4.7:0.55:0.77:0.25:0.96:2000.

[0072] (2) Then, a simulated mineralization solution was obtained by mixing deionized water, sodium chloride, sodium bicarbonate and calcium chloride in a mass ratio of 1:0.024:0.016:0.01. The porphyrin-based microporous polymer / polyurethane-coated modified single crystal high nickel cathode material was then placed in the simulated mineralization solution and mineralized at room temperature (25°C) for 20 hours to obtain slurry 2. The slurry 2 was then spray-dried at an outlet temperature of 110°C. In the above preparation process, the mass ratio of porphyrin-based microporous polymer / polyurethane-coated modified single crystal high nickel cathode material to simulated mineralization solution was 1:4.

[0073] Example 3

[0074] A high-temperature single-crystal high-nickel cathode material is prepared by the following steps:

[0075] S1. Preparation of modified single-crystal high-nickel cathode material:

[0076] (1) Single-crystal high-nickel cathode precursor Ni 0.8 Co 0.1 Al 0.1 (OH)₂ was dispersed in deionized water and stirred for 120 min to obtain a slurry. Cobalt sulfate and aluminum sulfate were then added to the slurry and stirred for 60 min in a high-speed mixer. Sodium hydroxide was added to adjust the pH to 10. The mixture was aged at 45℃ for 4.5 h, washed five times with deionized water, and dried at 120℃ to obtain a cobalt hydroxide and aluminum hydroxide composite layer coated single-crystal high-nickel cathode precursor. In the above preparation process, Ni… 0.8 Co 0.1 Al 0.1The mass ratio of (OH)2, cobalt sulfate, aluminum sulfate, and deionized water is 1:0.065:0.195:3.2.

[0077] (2) Coating the single-crystal high-nickel cathode precursor Ni with a cobalt hydroxide and aluminum hydroxide composite layer. 0.8 Co 0.1 Al 0.1 (OH)₂ and lithium carbonate were mixed at a mass ratio of 2.32:1 and sintered in a tube furnace at 880℃ for 15 hours. After crushing and sieving, the resulting material had a median particle size of 3 μm and a specific surface area of ​​0.72 m². 2 / g modified single-crystal high-nickel cathode material LiNi 0.8 Co 0.1 Al 0.1 O2.

[0078] S2, Preparation of single-crystal high-nickel cathode material coated with porphyrin-based microporous polymer:

[0079] The modified single-crystal high-nickel cathode material obtained in step S1, pyrrole, propionic acid, and tetra(4-aldehyde)phenylsilane were added to a reaction vessel after magnetic stirring for 1.5 h at a mass ratio of 1:0.00066:0.0004:0.24. The mixture was heated to 130 °C under nitrogen protection and reacted for 24 h. After the reaction was completed, the mixture was filtered. The filter cake was washed four times with deionized water, and then washed five times each with N,N-dimethylformamide, dichloromethane, and tetrahydrofuran. Finally, it was dried at 110 °C for 8 h to obtain the final product.

[0080] S3, Preparation of modified single-crystal high-nickel cathode material coated with porphyrin-based microporous polymer / polyurethane-calcium carbonate composite layer:

[0081] (1) The monocrystalline high-nickel cathode material coated and modified with isophorone diisocyanate and porphyrin-based microporous polymer was added to a reaction vessel equipped with a stirrer and heated to 80°C for 1.4 h. Then, polyethylene glycol was added and the temperature was raised to 92°C for 6.8 h. After cooling to 70°C, N,N-dimethyl-N',N'-di(2-hydroxypropyl)-1,3-propanediamine and 1,4-butanediol were added and the reaction was continued for 4.5 h. After the above reaction was completed, 2,2-dimethylolpropionic acid was added for neutralization. Finally, deionized water and porphyrin-based microporous polymer were added for coating and modification. Slurry 1 was prepared by high-speed emulsification of single-crystal high-nickel cathode material; the slurry 1 was then spray-dried at an outlet temperature of 80℃ to obtain the final product; in the above preparation steps, the mass ratio of porphyrin-based microporous polymer-coated modified single-crystal high-nickel cathode material, isophorone diisocyanate, polyethylene glycol, N,N-dimethyl-N',N'-di(2-hydroxypropyl)-1,3-propanediamine, 1,4-butanediol, 2,2-dimethylolpropionic acid, and deionized water was 1000:2.9:4.7:0.62:0.77:0.25:0.92:2000.

[0082] (2) Then, a simulated mineralization solution was obtained by mixing deionized water, sodium chloride, sodium bicarbonate and calcium chloride in a mass ratio of 1:0.022:0.014:0.0083; porphyrin-based microporous polymer / polyurethane-coated modified single crystal high nickel cathode material was placed in the simulated mineralization solution and mineralized at room temperature for 21.5 h to obtain slurry 2. The slurry 2 was then spray-dried at an outlet temperature of 105℃. In the above preparation process, the mass ratio of porphyrin-based microporous polymer / polyurethane-coated modified single crystal high nickel cathode material to simulated mineralization solution was 1:5.2.

[0083] Example 4

[0084] A high-temperature single-crystal high-nickel cathode material is prepared by the following steps:

[0085] S1. Preparation of modified single-crystal high-nickel cathode material:

[0086] (1) Single-crystal high-nickel cathode precursor Ni 0.9 Co 0.05 Al 0.05 (OH)₂ was dispersed in deionized water and stirred for 60 min to obtain a slurry. Cobalt sulfate and aluminum sulfate were then added to the slurry and stirred for 30 min in a high-speed mixer. Sodium hydroxide was added to adjust the pH to 11. The mixture was aged at 60℃ for 8 h, washed five times with deionized water, and dried at 200℃ to obtain a cobalt hydroxide and aluminum hydroxide composite layer coated single-crystal high-nickel cathode precursor. In the above preparation process, Ni… 0.9 Co 0.05 Al 0.05 The mass ratio of (OH)2, cobalt sulfate, aluminum sulfate, and deionized water is 1:0.045:0.135:3.2.

[0087] (2) Coating the single-crystal high-nickel cathode precursor Ni with a cobalt hydroxide and aluminum hydroxide composite layer. 0.9 Co 0.05 Al 0.05 (OH)₂ and lithium carbonate were mixed at a mass ratio of 2.15:1 and sintered in a tube furnace at 900℃ for 20 hours. After crushing and sieving, the resulting material had a median particle size of 5 μm and a specific surface area of ​​0.95 m². 2 / g modified single-crystal high-nickel cathode material LiNi 0.9 Co 0.05 Al 0.05 O2.

[0088] S2, Preparation of single-crystal high-nickel cathode material coated with porphyrin-based microporous polymer:

[0089] The modified single-crystal high-nickel cathode material obtained in step S1, pyrrole, propionic acid, and tetra(4-aldehyde)phenylsilane were added to a reaction vessel after magnetic stirring for 3 hours at a mass ratio of 1:0.0008:0.0004:0.26. The mixture was heated to 150℃ under nitrogen protection and reacted for 24 hours. After the reaction was completed, the mixture was filtered. The filter cake was washed 5 times with deionized water, and then washed 5 times each with N,N-dimethylformamide, dichloromethane, and tetrahydrofuran. Finally, it was dried at 120℃ for 12 hours to obtain the final product.

[0090] S3, Preparation of modified single-crystal high-nickel cathode material coated with porphyrin-based microporous polymer / polyurethane-calcium carbonate composite layer:

[0091] (1) Hexamethylene diisocyanate and porphyrin-based microporous polymer-coated modified single-crystal high-nickel cathode material were added to a reaction vessel equipped with a stirrer and heated to 58°C for 2.4 h. Then, polycaprolactone diol was added and the temperature was raised to 94°C for 8 h. After cooling to 76°C, N,N-dimethyl-N',N'-di(2-hydroxypropyl)-1,3-propanediamine and diethylene glycol were added and the reaction was continued for 6 h. After the above reaction was completed, 2,2-dimethylolpropionic acid was added for neutralization. Finally, deionized water and porphyrin-based microporous polymer-coated modified single-crystal high-nickel cathode material were added. Slurry 1 was prepared by high-speed emulsification of high-nickel crystalline cathode material; the slurry 1 was then spray-dried at an outlet temperature of 85℃ to obtain the final product; in the above preparation steps, the mass ratio of porphyrin-based microporous polymer-coated modified single-crystal high-nickel cathode material, hexamethylene diisocyanate, polycaprolactone diol, N,N-dimethyl-N',N'-di(2-hydroxypropyl)-1,3-propanediamine, diethylene glycol, 2,2-dimethylolpropionic acid, and deionized water was 1000:2.9:4.7:0.62:0.77:0.25:1.4:2000.

[0092] (2) Then, a simulated mineralization solution was obtained by mixing deionized water, sodium chloride, sodium bicarbonate and calcium chloride in a mass ratio of 1:0.026:0.02:0.011; porphyrin-based microporous polymer / polyurethane-coated modified single crystal high nickel cathode material was placed in the simulated mineralization solution and mineralized at room temperature for 24 hours to obtain slurry 2. The slurry 2 was spray-dried after setting the outlet temperature to 112℃. In the above preparation process, the mass ratio of porphyrin-based microporous polymer / polyurethane-coated modified single crystal high nickel cathode material to simulated mineralization solution was 1:6.

[0093] Example 5

[0094] A high-temperature single-crystal high-nickel cathode material is prepared by the following steps:

[0095] (1) Single-crystal high-nickel cathode precursor Ni 0.9 Co 0.05 Mn 0.05(OH)₂ was dispersed in deionized water and stirred for 82 min to obtain a slurry. Cobalt sulfate and aluminum sulfate were then added to the slurry and stirred for 50 min in a high-speed mixer. Ammonia was then added to adjust the pH to 9.4. The mixture was aged at 47℃ for 5.6 h, washed four times with deionized water, and dried at 155℃ to obtain a cobalt hydroxide and aluminum hydroxide composite layer coated single-crystal high-nickel cathode precursor. In the above preparation process, Ni… 0.9 Co 0.05 Mn 0.05 The mass ratio of (OH)2, cobalt sulfate, aluminum sulfate, and deionized water is 1:0.03:0.09:3.2.

[0096] (2) Coating the single-crystal high-nickel cathode precursor Ni with a cobalt hydroxide and aluminum hydroxide composite layer. 0.9 Co 0.05 Mn 0.05 (OH)₂ and lithium hydroxide were mixed at a mass ratio of 2.18:1 and sintered in a tube furnace at 845℃ for 11.4 h. After crushing and sieving, the resulting particles had a median particle size of 2.65 μm and a specific surface area of ​​0.88 m². 2 / g modified single-crystal high-nickel cathode material LiNi 0.9 Co 0.05 Mn 0.05 O2.

[0097] S2, Preparation of single-crystal high-nickel cathode material coated with porphyrin-based microporous polymer:

[0098] The modified single-crystal high-nickel cathode material obtained in step S1, pyrrole, propionic acid, and tetra(4-aldehyde)phenylsilane were added to a reaction vessel after being magnetically stirred for 2.4 h at a mass ratio of 1:0.0008:0.0004:0.26. The mixture was heated to 132 °C and reacted for 22.2 h under nitrogen and / or inert gas protection. After the reaction was completed, the mixture was filtered. The filter cake was washed 5 times with deionized water, and then washed 3 times each with N,N-dimethylformamide, dichloromethane, and tetrahydrofuran. Finally, it was dried at 96 °C for 8.5 h to obtain the final product.

[0099] S3, Preparation of modified single-crystal high-nickel cathode material coated with porphyrin-based microporous polymer / polyurethane-calcium carbonate composite layer:

[0100] (1) Hexamethylene diisocyanate and porphyrin-based microporous polymer-coated modified single-crystal high-nickel cathode material were added to a reaction vessel equipped with a stirrer and heated to 62°C for 3.6 h. Polypropylene glycol was then added and the temperature was raised to 86°C for 5.5 h. The temperature was then lowered to 68°C and N,N-dimethyl-N',N'-di(2-hydroxypropyl)-1,3-propanediamine and diethylene glycol were added and the reaction continued for 5.8 h. After the above reaction was completed, acetic acid was added for neutralization. Finally, deionized water and porphyrin-based microporous polymer-coated modified single-crystal high-nickel cathode material were added. Slurry 1 was prepared by high-speed emulsification of single-crystal high-nickel cathode material; the slurry 1 was then spray-dried at an outlet temperature of 86℃ to obtain the final product; in the above preparation steps, the mass ratio of porphyrin-based microporous polymer-coated modified single-crystal high-nickel cathode material, hexamethylene diisocyanate, polypropylene glycol, N,N-dimethyl-N',N'-di(2-hydroxypropyl)-1,3-propanediamine, diethylene glycol, acetic acid, and deionized water was 1000:2.9:4.7:0.5:0.77:0.25:0.96:2000.

[0101] (2) Then, a simulated mineralization solution was obtained by mixing deionized water, sodium chloride, sodium bicarbonate and calcium chloride in a mass ratio of 1:0.02:0.012:0.0084. The porphyrin-based microporous polymer / polyurethane-coated modified single crystal high nickel cathode material was then placed in the simulated mineralization solution and mineralized at room temperature for 18 hours to obtain slurry 2. The slurry 2 was then spray-dried at an outlet temperature of 106℃. In the above preparation process, the mass ratio of porphyrin-based microporous polymer / polyurethane-coated modified single crystal high nickel cathode material to simulated mineralization solution was 1:4.5.

[0102] Comparative Example 1

[0103] Ni single-crystal high-nickel cathode precursor 0.7 Co 0.05 Mn 0.25 (OH)2 and lithium hydroxide were mixed and sintered in a tube furnace at 800℃ for 10 hours. The resulting material was then crushed and sieved to produce a single-crystal high-nickel cathode material.

[0104] Comparative Example 2

[0105] A single-crystal high-nickel cathode material is prepared by the following steps:

[0106] (1) Single-crystal high-nickel cathode precursor Ni 0.8 Co 0.1 Mn 0.1(OH)₂ was dispersed in deionized water and stirred for 40 min to obtain a slurry. Cobalt sulfate and aluminum sulfate were then added to the slurry and mixed for 45 min in a high-speed mixer. Ammonia was then added to adjust the pH to 10.5. The mixture was aged at 50°C for 6 h, washed five times with deionized water, and dried at 160°C to obtain a single-crystal high-nickel cathode precursor coated with a cobalt hydroxide and aluminum hydroxide composite layer. In the above preparation process, Ni… 0.8 Co 0.1 Mn 0.1 The mass ratio of (OH)2, cobalt sulfate, aluminum sulfate, and deionized water is 1:0.05:0.15:3.2.

[0107] (2) Coating the single-crystal high-nickel cathode precursor Ni with a cobalt hydroxide and aluminum hydroxide composite layer. 0.8 Co 0.1 Mn 0.1 (OH)₂ was mixed with lithium hydroxide and sintered in a tube furnace at 840℃ for 13.5 h. After crushing and sieving, the resulting material had a median particle size of 4 μm and a specific surface area of ​​0.65 m². 2 / g modified single-crystal high-nickel cathode material LiNi 0.8 Co 0.1 Mn 0.1 O2.

[0108] Comparative Example 3

[0109] A single-crystal high-nickel cathode material is prepared by the following steps:

[0110] S1, Ni single-crystal high-nickel cathode precursor 0.8 Co 0.1 Al 0.1 (OH)2 was mixed with lithium carbonate and sintered in a tube furnace at 880°C for 15 hours. After crushing and sieving, a single-crystal high-nickel cathode material was obtained.

[0111] S2, Preparation of single-crystal high-nickel cathode material coated with porphyrin-based microporous polymer:

[0112] The single-crystal high-nickel cathode material obtained in step S1, pyrrole, propionic acid, and tetra(4-aldehyde)phenylsilane were added to a reaction vessel after magnetic stirring for 1.5 h at a mass ratio of 1:0.00066:0.0004:0.24. The mixture was heated to 130 °C under nitrogen protection and reacted for 24 h. After the reaction was completed, the mixture was filtered. The filter cake was washed four times with deionized water, and then washed five times each with N,N-dimethylformamide, dichloromethane, and tetrahydrofuran. Finally, it was dried at 110 °C for 8 h to obtain the final product.

[0113] S3, Preparation of single-crystal high-nickel cathode material coated with porphyrin-based microporous polymer / polyurethane-calcium carbonate composite layer:

[0114] Isophorone diisocyanate and porphyrin-based microporous polymer-coated single-crystal high-nickel cathode material were added to a reaction vessel equipped with a stirrer and heated to 80°C for 1.4 h. Polyethylene glycol was then added and the temperature was raised to 92°C for 6.8 h. The temperature was then lowered to 70°C, and N,N-dimethyl-N',N'-di(2-hydroxypropyl)-1,3-propanediamine and 1,4-butanediol were added, and the reaction continued for 4.5 h. After the above reaction was completed, 2,2-dimethylolpropionic acid was added for neutralization. Finally, deionized water and porphyrin-based microporous polymer-coated single-crystal cathode material were added. Slurry 1 was prepared by high-speed emulsification of high-nickel cathode material; the slurry 1 was then spray-dried at an outlet temperature of 80℃ to obtain the final product; in the above preparation steps, the mass ratio of porphyrin-based microporous polymer-coated single-crystal high-nickel cathode material, isophorone diisocyanate, polyethylene glycol, N,N-dimethyl-N',N'-di(2-hydroxypropyl)-1,3-propanediamine, 1,4-butanediol, 2,2-dimethylolpropionic acid, and deionized water was 1000:2.9:4.7:0.62:0.77:0.25:0.92:2000.

[0115] (2) Then, a simulated mineralization solution was obtained by mixing deionized water, sodium chloride, sodium bicarbonate and calcium chloride in a mass ratio of 1:0.022:0.014:0.0083; porphyrin-based microporous polymer / polyurethane-coated single-crystal high-nickel cathode material was placed in the simulated mineralization solution and mineralized at room temperature for 21.5 h to obtain slurry 2. The slurry 2 was then spray-dried at an outlet temperature of 105℃. In the above preparation process, the mass ratio of porphyrin-based microporous polymer / polyurethane-coated single-crystal high-nickel cathode material to simulated mineralization solution was 1:5.2.

[0116] Test methods

[0117] Ternary lithium-ion pouch batteries were prepared using the ternary cathode materials obtained in the comparative examples and embodiments above, with the same proportion of active materials. These were labeled as Test Examples 1-5 and Comparative Test Examples 1-3, respectively. The cathode electrode was prepared by mixing, coating, and rolling with a positive active material:PVDF:CNTs mass ratio of 98:1:1. The anode electrode was prepared by mixing, coating, and rolling with a negative active material (graphite):CMC (carboxymethyl cellulose):SP (conductive carbon black) mass ratio of 96.2:3:0.8. Finally, the cathode, PP and / or PE porous separator, and anode were stacked in sequence, sealed with tape, and packaged with aluminum-plastic film with perforations. 10-15g of electrolyte was injected using a 1mol / L LiPF6 solution dissolved in a mixed solution of ethylene carbonate and dimethyl carbonate (wt% = 1:1). The battery cell was then evacuated and sealed to obtain the experimental battery cell. The ternary lithium-ion pouch batteries are identical in all materials except the cathode material, dosage, and manufacturing method. The following tests were conducted:

[0118] (1) Test of the rate retention rate of soft pack battery: charge from 2.8V to 4.2V at 1C constant current, maintain 4.2V constant voltage charging, cut off current 0.05C; then discharge to 2.8V at 1C, 2C and 3C respectively, and record the discharge capacity retention rate at different rates in turn;

[0119] (2) Soft-pack battery volume expansion rate test: The water displacement method was used for testing. The specific test steps are as follows: The battery cell made of the positive electrode material prepared using the example and comparative example was immersed in a beaker containing water, and the scale was recorded and marked as V0; then the battery after being cycled at 65℃ for 100, 200 and 300 cycles was immersed in a beaker containing water, and the scale was recorded and marked as V1, V2 and V3 respectively; the expansion rate was calculated according to the formula: (Vm-V0) / V0*100, m=1, 2, 3; the cycle steps are as follows: charge from 2.8V to 4.2V at 1C constant current, maintain 4.2V constant voltage charging, cut off current 0.05C; then charge and discharge cyclically from 1C to 2.8V;

[0120] (3) Gas composition test of soft pack battery: Take the battery from (2) after 300 cycles of charge and discharge, place it in a high temperature oven at 90°C for 7 days, and then place it in a glove box to extract the gas in the battery. Gas composition test is performed by gas chromatography.

[0121] The test results for the battery rate retention rate and battery volume expansion rate are shown in Table 1.

[0122] Table 1

[0123]

[0124] Table 2 shows the test results of the proportion of gas components in the battery.

[0125] Table 2

[0126]

[0127]

[0128] Based on the test data in Table 1 and the cathode material preparation schemes of Examples 1-5 and Comparative Example 2, it can be seen that, compared with Comparative Examples 1 and 3, Examples 1-5 and Comparative Example 2 all maintained a capacity retention rate of over 90% at 3C rate. Furthermore, combining the test results of Examples 1-5 and Comparative Example 3, it can be seen that the volume expansion rate after cycling at 65°C is significantly lower than that of Comparative Examples 1 and 2, indicating that the composite layer coating can effectively reduce the gas generation during battery cycling, thereby solving the battery volume expansion problem.

[0129] As can be seen from Table 2, the proportion of CO2 in the gas composition measured in Test Examples 1-5 and Comparative Test Example 3 is much smaller than that in Comparative Test Examples 1 and 2, indicating that the coating of the composite layer can effectively absorb CO2 generated by residual alkali during high-temperature cycling and storage. In addition, the coating effect of the composite layer improves the interfacial side reactions between the electrolyte and the positive electrode, thereby reducing the production of C2H6, C2H4 and CH4 during high-temperature cycling of the battery.

[0130] Depend on Figure 1 As can be seen from the test microstructure images, compared with Comparative Example 1, the composite coating layer prepared in Example 1 is more uniform and effectively coated on its surface.

[0131] In summary, through the synergistic effect of co-doping of cobalt and aluminum and the porphyrin-based microporous polymer / polyurethane-calcium carbonate (PACMP / PU-CaCO3) composite layer, the gas generation and interfacial side reactions between the electrode and electrolyte in the prepared lithium-ion battery during high-temperature cycle charging and discharging are effectively reduced, thus solving the problem of battery capacity degradation caused by edge lithium plating due to bubble accumulation inside the battery.

[0132] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a high-temperature single-crystal high-nickel cathode material, characterized in that, Includes the following steps: 1) The coated single-crystal high-nickel cathode precursor was mixed with a lithium source and sintered. After crushing and sieving, the modified single-crystal high-nickel cathode material LiNi was obtained. x Co y T 1-x-y O2; In step 1), the preparation of the coated single-crystal high-nickel cathode precursor includes the following steps: coating the single-crystal high-nickel cathode precursor Ni x Co y T 1-x-y (OH)2 is dispersed in deionized water and stirred to obtain a slurry; a coating agent is added to the slurry and the pH value is adjusted, and then the slurry is aged, filtered, washed and dried to obtain the coated single crystal high nickel cathode precursor; The coating agent is prepared by mixing cobalt sulfate and aluminum sulfate in a mass ratio of 1:3 in a high-speed mixer for 25-60 minutes. 2) The modified single-crystal high-nickel cathode material LiNi x Co y T 1-x-y O2, pyrrole, propionic acid and tetra(4-aldehyde)phenylsilane are mixed and reacted in nitrogen and / or an inert atmosphere to obtain porphyrin-based microporous polymer-coated modified single-crystal high-nickel cathode material. 3) The monocrystalline high-nickel cathode material coated with diisocyanate and porphyrin-based microporous polymer is mixed and reacted, followed by the addition of diol and then N,N-dimethyl-N',N'-di(2-hydroxypropyl)-1,3-propanediamine and chain extender are added to continue the reaction. After the above reaction is completed, a salting agent is added for neutralization, and finally deionized water is added for high-speed emulsification to obtain a mixed slurry. The mixed slurry is spray-dried once to obtain polyurethane / porphyrin-based microporous polymer coated and modified monocrystalline high-nickel cathode material. Then, it is placed in a simulated mineralization solution for mineralization and spray-dried a second time to obtain porphyrin-based microporous polymer / polyurethane-calcium carbonate composite layer coated and modified monocrystalline high-nickel cathode material, which is the high-temperature monocrystalline high-nickel cathode material.

2. The method according to claim 1, characterized in that, In step (1), the chemical formula of the modified single-crystal high-nickel cathode precursor is Ni. x Co y T 1-x-y (OH)2, where 0.7≤x<1, 0<y≤0.1, and T is Mn and / or Al.

3. The method according to claim 2, characterized in that, The mass ratio of the single-crystal high-nickel cathode precursor, the coating agent, and the deionized water is 1:0.1~0.26:3.2; The stirring and mixing time is 20~120 min; The pH value was adjusted to 9-11 using ammonia and / or sodium hydroxide. The aging temperature is 40~60℃, and the aging time is 4~8h.

4. The method according to claim 1 or 2, characterized in that, In step 1), the mass ratio of the coated single-crystal high-nickel cathode precursor to the lithium source is 2.01~2.32:1; The lithium source is lithium hydroxide and / or lithium carbonate; The sintering temperature is 800~900℃, and the time is 10~20h; The modified single-crystal high-nickel cathode material LiNi x Co y T 1-x-y The median particle size of O2 is 2~5μm; The modified single-crystal high-nickel cathode material LiNi x Co y T 1-x-y The specific surface area of ​​O2 is 0.55~0.95m². 2 / g.

5. The method according to claim 1 or 2, characterized in that, In step 2), the mass ratio of modified single-crystal high-nickel cathode material, pyrrole, propionic acid, and tetrakis(4-aldehyde)phenylsilane is 1:0.0006~0.0008:0.0004:0.1~0.26; The reaction temperature is 120~150℃, and the reaction time is 20~24h.

6. The method according to claim 1 or 2, characterized in that, In step 2), after the reaction is completed, the steps of filtration, washing, and drying are also included; The post-filtration washing process is as follows: the filter cake is washed with deionized water 3-5 times, and then washed with N,N-dimethylformamide, dichloromethane, and tetrahydrofuran 3-5 times each in sequence. The drying temperature is 80~120℃, and the drying time is 6~12h.

7. The method according to claim 1 or 2, characterized in that, In step 3), the temperature of the mixing reaction is 40~80℃, and the time is 1~4h; The reaction temperature for adding the diol is 84~94℃, and the time is 4~8h; The temperature at which N,N-dimethyl-N',N'-di(2-hydroxypropyl)-1,3-propanediamine is added is 62~76℃, the temperature at which it reacts with the chain extender is 62~76℃, and the reaction time is 3~6h. The outlet temperature of the spray dryer is 60~90℃.

8. The method according to claim 1 or 2, characterized in that, The mass ratio of the porphyrin-based microporous polymer-coated modified single-crystal high-nickel cathode material, the diisocyanate, the diol, the N,N-dimethyl-N',N'-di(2-hydroxypropyl)-1,3-propanediamine, the chain extender, the salt-forming agent, and the deionized water is 1000:2.9:4.7:0.41~0.62:0.77:0.25:0.8~1.4:2000; The diisocyanate is selected from at least one of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate; The diol is selected from at least one of poly(1,6-hexanediol carbonate), polytetrahydrofuran ether diol, polyethylene glycol, polycaprolactone diol, and polypropylene oxide diol. The chain extender is selected from 1,4-butanediol and / or diethylene glycol; The salt-forming agent is selected from at least one of acetic acid, 3-carboxy-3-hydroxyglutaric acid, and 2,2-dihydroxymethylpropionic acid.

9. The method according to claim 1 or 2, characterized in that, The simulated mineralization solution was obtained by mixing deionized water, sodium chloride, sodium bicarbonate, and calcium chloride in a mass ratio of 1:0.02~0.026:0.012~0.02:0.008~0.

011. The mass ratio of the polyurethane / porphyrin-based microporous polymer-coated modified single-crystal high-nickel cathode material to the simulated mineralization solution is 1:3~6; The mineralization time is 18-24 hours; The outlet temperature of the secondary spray dryer is 100~120℃.

10. The high-temperature single-crystal high-nickel cathode material prepared by the preparation method according to any one of claims 1-8.

11. A lithium-ion battery, characterized in that, It includes a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the positive electrode is made of the high-temperature single-crystal high-nickel positive electrode material as described in claim 10.

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