A lithium cobalt oxide cathode material, its preparation method and application

Abstract

This invention belongs to the field of lithium battery technology, specifically relating to a lithium cobalt oxide cathode material, its preparation method, and its application. When the D50 particle size of the lithium cobalt oxide cathode material is 10–20 μm, its specific surface area is 0.4–0.8 m². 2 / g; the actual density of the lithium cobalt oxide cathode material is 4.85–5.03 g / cm³. 3 The tap density is 2.35–2.50 g / cm³. 3 The lithium cobalt oxide cathode material has an R3-m space group structure, and the peak intensity ratio of the 003 peak to the 104 peak in the XRD spectrum of the lithium cobalt oxide cathode material is I(003) / I(104) ≥ 2.5. The key to this invention is to introduce an inert gas into the Li-Na hydrothermal exchange system to form an aerosol, and to carry out Li-Na exchange under the protection of the aerosol, so that the D50 particle size, specific surface area, true density, tap density, and the I(003) / I(104) of the XRD of the lithium cobalt oxide cathode material are within a specific parameter range. The resulting lithium cobalt oxide cathode material has excellent lithium insertion / extraction kinetics, thereby giving the lithium-ion battery excellent capacity and rate performance.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery technology, specifically relating to a lithium cobalt oxide cathode material, its preparation method, and its application. Background Technology

[0002] With the development and advancement of lithium-ion battery technology, increasingly higher demands are being placed on its capacity. In the composition of a lithium-ion battery, the capacity of the cathode material is a crucial factor affecting its overall capacity. One important approach to improving lithium-ion battery capacity is to increase its charge and discharge voltage. However, as the charging voltage increases, the cathode material faces a series of problems, including unstable crystal structure, rapid capacity decay, and a significant reduction in cycle performance.

[0003] Lithium cobalt oxide (LiCoO2, LCO), a common cathode material for lithium-ion batteries, is frequently used in consumer electronics (3C) batteries such as mobile phones and tablets due to its high compaction density and high energy density. Currently, existing technologies often employ sodium-based solid-state sintering of the cathode material followed by Li-Na ion exchange to obtain lithium cobalt oxide with an O2 phase stacked structure. This structure is more stable than O3 phase lithium cobalt oxide and exhibits multiple charge-discharge phase transition platforms during electrochemical processes, thus better demonstrating its electrochemical performance. However, the O2 phase lithium cobalt oxide material prepared using the above method still suffers from capacity decay in the high charging voltage range, limiting its improvement on the capacity and cycle performance of both the cathode material and the lithium-ion battery.

[0004] Therefore, improving the interfacial stability of cathode materials under high voltage and developing a lithium-ion battery cathode material with high specific capacity, rate performance and good cycle performance is a very critical task. Summary of the Invention

[0005] One of the objectives of this invention is to provide a lithium cobalt oxide cathode material that has excellent capacity and rate performance, and can be well applied in the production and manufacturing of high energy density lithium-ion batteries.

[0006] The second objective of this invention is to provide a method for preparing lithium cobalt oxide cathode material.

[0007] The third objective of this invention is to provide a lithium cobalt oxide cathode material prepared by the above method.

[0008] The fourth objective of this invention is to provide the application of the aforementioned lithium cobalt oxide cathode material in lithium-ion batteries.

[0009] Specifically, when the D50 particle size of the lithium cobalt oxide cathode material provided by this invention is 10–20 μm, its specific surface area is 0.4–0.8 m². 2 / g; the actual density of the lithium cobalt oxide cathode material is 4.85–5.03 g / cm³. 3 The tap density is 2.35–2.50 g / cm³. 3 In the XRD spectrum of the lithium cobalt oxide cathode material, the lithium cobalt oxide cathode material has an R3-m space group structure, and the peak intensity ratio of the 003 peak to the 104 peak in the XRD spectrum of the lithium cobalt oxide cathode material is I(003) / I(104)≧2.5.

[0010] In a preferred embodiment, in the XRD spectrum of the lithium cobalt oxide cathode material, the 2θ value of the 003 peak is 18.7–19.2°, and the 2θ value of the 104 peak is 45.0–45.5°.

[0011] In a preferred embodiment, the general chemical formula of the lithium cobalt oxide cathode material is Li. y Na z Co 1-a- b A a M b O2, wherein 0.93≤y≤1.02, 0≤z≤0.02, 0≤a≤0.1, 0≤b≤0.05, A is selected from Ni and / or Mn, and M is selected from at least one of Al, Mg, Ti, Tc, Mo, Ca, W, Nb, Zr, La, and Y.

[0012] In a preferred embodiment, M is selected from at least one of Al, Mg, Ti, and Y.

[0013] In a preferred embodiment, the Na content in the lithium cobalt oxide cathode material is less than 500 ppm.

[0014] The method for preparing lithium cobalt oxide cathode material provided by the present invention includes the following steps:

[0015] S1. Mix the lithium cobalt oxide cathode material precursor with a sodium source, and then sinter the resulting mixture to obtain a sodium-containing semi-finished material.

[0016] S2. After mixing the sodium-containing semi-finished material with the lithium source, an inert gas is introduced to form an aerosol. The reaction system is then subjected to a hydrothermal reaction. After the reaction is completed, the solid product is obtained by solid-liquid separation, water washing, and drying, which is the lithium cobalt oxide cathode material.

[0017] In a preferred embodiment, in step S1, the lithium cobalt oxide cathode material precursor has (Co) 1-a- b A a M b )3O4 and / or Co 1-a-b A a Mb The structure shown in (OH)2, wherein 0≤a≤0.1, 0≤b≤0.05, A is selected from Ni and / or Mn, and M is selected from at least one of Al, Mg, Ti, Tc, Mo, Ca, W, Nb, Zr, La, and Y.

[0018] In a preferred embodiment, in step S1, M is selected from at least one of Al, Mg, Ti, and Y.

[0019] In a preferred embodiment, in step S1, the sodium source is selected from at least one of sodium carbonate, sodium hydroxide, sodium bicarbonate, sodium nitrate, sodium sulfate, sodium acetate, and sodium oxalate.

[0020] In a preferred embodiment, in step S1, the molar ratio of Co in the lithium cobalt oxide cathode material to Na in the sodium source is 1:(0.75~1.20).

[0021] In a preferred embodiment, in step S1, the sintering treatment temperature is 700–1000°C and the time is 16–48 h.

[0022] In a preferred embodiment, in step S2, the lithium source is selected from at least one of lithium hydroxide, lithium nitrate, lithium carbonate, lithium chloride, lithium bromide, and lithium iodide.

[0023] In a preferred embodiment, in step S2, the molar ratio of Na in the sodium-containing semi-finished material to Li in the lithium source is 1:(1-4).

[0024] In a preferred embodiment, step S2, the process of mixing the sodium-containing semi-finished material with the lithium source and then introducing an inert gas to form an aerosol, includes: mixing the lithium source and water to obtain a lithium source solution, first heating the reaction system containing the lithium source solution to 80-100°C, then adding the sodium-containing semi-finished material and introducing an inert gas into the reaction system to form an aerosol.

[0025] In a preferred embodiment, in step S2, the conditions for the hydrothermal reaction include a temperature of 160–200°C and a time of 2–6 hours.

[0026] In a preferred embodiment, in step S2, the solid content of the reaction system during the hydrothermal reaction is 40-60 wt%.

[0027] In a preferred embodiment, in step S2, the inert gas is selected from at least one of nitrogen, neon, argon, xenon, and radon.

[0028] In a preferred embodiment, in step S2, the amount of inert gas introduced is such that the pressure of the reaction system is 0.3 to 2.0 MPa.

[0029] In a preferred embodiment, in step S2, the inert gas is introduced at a flow rate of 2-5 L / min for 1-5 min.

[0030] After extensive and in-depth research, the inventors of this invention discovered that in the existing technology for preparing lithium cobalt oxide materials using a combination of sodium-based solid-state sintering and Li-Na ion exchange, significant internal defects arise due to the shrinkage of the unit cell volume during the replacement process. This leads to a significant increase in the specific surface area of ​​the cathode material. An excessively large specific surface area not only reduces the crystal structure stability of the cathode material but also causes problems such as gas generation and increased side reactions when applied in lithium-ion batteries, which is detrimental to improving the capacity and rate performance of lithium-ion batteries and results in poor cycle performance. Furthermore, it was found that controlling the formation of specific crystal plane structures in the cathode material is beneficial for improving its lithium-ion insertion / extraction kinetics.

[0031] Beneficial effects: The key to this invention lies in introducing an inert gas into the Li-Na hydrothermal exchange system to form an aerosol, and carrying out Li-Na exchange under the protection of the aerosol, so that the specific surface area of ​​the lithium cobalt oxide cathode material is 0.4-0.8 m² when the D50 particle size is within 10-20 μm. 2 / g, actual density is 4.85~5.03g / cm³ 3 The tap density is 2.35–2.50 g / cm³. 3 Furthermore, the lithium cobalt oxide cathode material possesses an R3-m space group structure, and the peak intensity ratio of the 003 peak to the 104 peak in the XRD spectrum of the lithium cobalt oxide cathode material is I(003) / I(104)≧2.5. In this case, the lithium cobalt oxide cathode material exhibits excellent lithium-ion insertion / extraction kinetics, thus demonstrating superior capacity and rate performance compared to traditional lithium cobalt oxide materials. The possible reason is that due to its unique 003 and 104 crystal plane growth structure, where the 003 crystal plane is the lithium-ion insertion / extraction plane, I(003) / I(104)≧2.5 indicates the full exposure of the 003 crystal plane. Combined with the pore size and particle size morphology characteristics of the lithium cobalt oxide cathode material, this allows the cathode material to have more lithium-ion insertion / extraction channels and better lithium-ion insertion / extraction performance, making the lithium cobalt oxide cathode material more advantageous in charge / discharge kinetics and possessing good structural stability, thereby improving its capacity and rate performance.

[0032] In a preferred embodiment, when the lithium cobalt oxide cathode material further contains at least one of metal elements A and / or M, its cycle performance can be further improved while ensuring the high capacity performance of the cathode material. Detailed Implementation

[0033] The lithium cobalt oxide cathode material provided by this invention has a D50 particle size of 10–20 μm, such as 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, or any value between them; its specific surface area is 0.4–0.8 m². 2 / g, such as 0.4m 2 / g, 0.5m 2 / g, 0.6m 2 / g, 0.7m 2 / g, 0.8m 2 / g or any value between them, which is beneficial for providing more channels for the lithium cobalt oxide cathode material during the electrochemical lithium insertion / extraction process, improving the kinetic performance of lithium insertion / extraction, and ensuring the stability of the crystal structure of the material during the process, thus enabling the lithium-ion battery to have excellent capacity and rate performance. The actual density of the lithium cobalt oxide cathode material is 4.85–5.03 g / cm³. 3 For example, 4.85 g / cm³ 3 4.88 g / cm 3 4.90 g / cm 3 4.92g / cm 3 4.95g / cm 3 4.98g / cm 3 5.00g / cm 3 5.03 g / cm 3 Or any value between them, the tap density is 2.35–2.50 g / cm³. 3 For example, 2.35g / cm 3 2.38g / cm 3 2.40 g / cm 3 2.42 g / cm 3 2.45g / cm 3 2.48 g / cm 3 2.50g / cm 3Or any value between them, at which point the lithium cobalt oxide cathode material has good capacity and rate performance advantages. This is because, compared with traditional lithium cobalt oxide materials, the lower true density can increase the cell volume of the material. Under the same chemical formula, the material crystallographic c-axis is larger, which is beneficial to the lithium ion insertion and extraction during the charging and discharging process, thereby reducing the material impedance and improving the specific capacity and rate performance of the cathode material. In the XRD spectrum of the lithium cobalt oxide cathode material, the lithium cobalt oxide cathode material has an R3-m space group structure, and the peak intensity ratio of the 003 peak to the 104 peak in the XRD spectrum of the lithium cobalt oxide cathode material is I(003) / I(104)≧2.5. At this time, the lithium cobalt oxide cathode material has good capacity and rate performance advantages because the 003 crystal plane is the lithium ion insertion and extraction crystal plane. The full exposure of the 003 crystal plane can give the cathode material better lithium ion insertion and extraction channels and better lithium ion insertion and extraction performance, thus making the cathode material more advantageous in charge and discharge kinetics, thereby giving full play to capacity performance and improving rate performance. The ratio of I(003) / I(104) is preferably 2.5 to 3.8, such as 2.5, 2.6, 2.8, 3.0, 3.2, 3.5, 3.6, 3.8 or any value between them.

[0034] In addition, the term "D50 particle size" refers to the particle size at which the cumulative particle size distribution percentage of a sample reaches 50%.

[0035] In this invention, in the XRD spectrum of the lithium cobalt oxide cathode material, the 2θ value of the 003 peak is preferably 18.7 to 19.2°, and the 2θ value of the 104 peak is preferably 45.0 to 45.5°.

[0036] In this invention, the preferred chemical formula of the lithium cobalt oxide cathode material is Li. y Na z Co 1-a-b A a M bO2. Preferably, 0.93 ≤ y ≤ 1.02, where y can be 0.93, 0.95, 0.98, 1.00, 1.01, 1.02, or any value between them. Preferably, 0 ≤ z ≤ 0.02, where z can be 0, 0.005, 0.01, 0.015, 0.01, or any value between them. Preferably, 0 ≤ a ≤ 0.1, where a can be 0, 0.02, 0.05, 0.08, 0.1, or any value between them. Preferably, 0 ≤ b ≤ 0.05, where b can be 0, 0.01, 0.02, 0.03, 0.04, 0.05, or any value between them. The preferred element A is Ni and / or Mn. In this case, the lithium cobalt oxide cathode material exhibits better electrochemical cycling performance because Ni and / or Mn can provide stability to the Co layer structure, thereby delaying structural collapse during the electrochemical lithium insertion / extraction process and improving the material's cycling performance. The preferred element M is at least one selected from Al, Mg, Ti, Tc, Mo, Ca, W, Nb, Zr, La, and Y. In this case, the lithium cobalt oxide cathode material exhibits better rate performance and cycling performance because M doping can significantly reduce the metal-O bond length in the cathode material structure and reduce polarization. The preferred element M is at least one selected from Al, Mg, Ti, and Y, which is more conducive to improving the cathode material's cycling performance.

[0037] In this invention, the Na content in the lithium cobalt oxide cathode material is preferably less than 500 ppm. This has the advantage of improving cycle performance because an appropriate amount of Na doping can help support the cathode material structure, reduce the volume change rate of the cathode material after lithium extraction, and further optimize cycle performance.

[0038] The method for preparing lithium cobalt oxide cathode material provided by the present invention includes the following steps:

[0039] S1. Mix the lithium cobalt oxide cathode material precursor with a sodium source, and then sinter the resulting mixture to obtain a sodium-containing semi-finished material.

[0040] S2. The sodium-containing semi-finished material is subjected to a hydrothermal reaction with a lithium source. The hydrothermal reaction is carried out under the protection of an aerosol formed by an inert gas. After the reaction is completed, the solid product is obtained by solid-liquid separation, water washing and drying, which is the lithium cobalt oxide cathode material.

[0041] In this invention, in step S1, the lithium cobalt oxide cathode material precursor preferably has (Co) 1-a-b A a M b )3O4 or Co 1-a-b A a M bThe structure shown in (OH)₂ indicates that the lithium cobalt oxide cathode material precursor can be at least one of cobalt tetroxide, cobalt hydroxide, cobalt tetroxide containing A, cobalt hydroxide containing A, cobalt tetroxide containing M, cobalt hydroxide containing M, cobalt tetroxide containing both A and M, and cobalt hydroxide containing both A and M. It possesses (Co)₂... 1-a-b A a M b )3O4 or Co 1-a-b A a M b Compounds with the structure shown in (OH)₂ can be purchased or prepared using existing methods. Specifically, Co 1-a-b A a M b (OH)₂ can be prepared by coprecipitation: cobalt salt and optionally salts A and M are coprecipitated with an alkaline precipitant, and the solid product after washing and drying is Co. 1-a-b A a M b (OH)2. Specifically, (Co 1-a-b A a M b Cobalt 3O4 can be obtained by heat treatment of cobalt salt and optional A salt and M salt, or by first co-precipitating cobalt salt and optional A salt and M salt with an alkaline precipitant, and then heat-treating the solid product after washing and drying. Wherein, 0 ≤ a ≤ 0.1, where a can be 0, 0.02, 0.05, 0.08, 0.1 or any value between them; 0 ≤ b ≤ 0.05, where b can be 0, 0.01, 0.02, 0.03, 0.04, 0.05 or any value between them; A is preferably from Ni and / or Mn; M is preferably from at least one of Al, Mg, Ti, Tc, Mo, Ca, W, Nb, Zr, La, and Y, more preferably from at least one of Al, Mg, Ti, and Y.

[0042] In this invention, in step S1, the sodium source can be any of the existing Na-containing compounds used to prepare cathode materials, including but not limited to at least one of sodium carbonate, sodium hydroxide, sodium bicarbonate, sodium nitrate, sodium sulfate, sodium acetate, and sodium oxalate.

[0043] In this invention, in step S1, the molar ratio of Co in the lithium cobalt oxide cathode material to Na in the sodium source is preferably 1:(0.75~1.20), such as 1:0.75, 1:0.80, 1:0.85, 1:0.90, 1:0.95, 1:1.00, 1:1.05, 1:1.10, 1:1.15, 1:1.20 or any value between them.

[0044] In this invention, in step S1, the sintering temperature is preferably 700-1000℃, such as 700℃, 750℃, 800℃, 850℃, 900℃, 950℃, 1000℃ or any value between them; the time is preferably 16-48h, such as 16h, 20h, 24h, 28h, 30h, 36h, 40h, 44h, 48h or any value between them.

[0045] In this invention, in step S2, the lithium source can be any existing Li-containing compound used to prepare cathode materials, including but not limited to at least one of lithium hydroxide, lithium nitrate, lithium carbonate, lithium chloride, lithium bromide, and lithium iodide.

[0046] In this invention, in step S2, the molar ratio of Na in the sodium-containing semi-finished material to Li in the lithium source is preferably 1:(1-4), such as 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4 or any value between them.

[0047] In this invention, step S2, the process of mixing the sodium-containing semi-finished material with a lithium source and then introducing an inert gas to form an aerosol, preferably includes: mixing the lithium source and water to obtain a lithium source solution; first heating the reaction system containing the lithium source solution to 80-100°C; then adding the sodium-containing semi-finished material and introducing an inert gas into the reaction system to form an aerosol. The temperature at which the sodium-containing semi-finished material is added to the reaction system is preferably controlled at 80-100°C, such as 80°C, 85°C, 90°C, 95°C, 100°C, or any value between them. This feed temperature is more conducive to increasing the Li-Na replacement rate while reducing the H-Na replacement rate, allowing Li-Na to be fully replaced to provide more lithium ions that can be inserted and extracted into the cathode material and improving the material's structural stability, thereby improving the cycle performance of the cathode material.

[0048] In this invention, the solid content of the reaction system during the hydrothermal reaction is preferably 40–60 wt%, such as 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, or any value between them. This is more conducive to the Li-Na substitution reaction, and more conducive to controlling the Na content of the lithium cobalt oxide cathode material to within 500 ppm, thereby increasing the Li concentration of the lithium cobalt oxide cathode material and thus improving the capacity and rate performance of the cathode material.

[0049] In this invention, specific examples of the inert gas include, but are not limited to, at least one of nitrogen, neon, argon, xenon, and radon.

[0050] In this invention, the amount of inert gas introduced is preferably such that the pressure of the reaction system is 0.3–2.0 MPa. Specifically, the flow rate of the inert gas is preferably 2–5 L / min, such as 2 L / min, 2.5 L / min, 3 L / min, 3.5 L / min, 4 L / min, 4.5 L / min, 5 L / min, or any value between them, and the introduction time is preferably 1–5 min, such as 1 min, 2 min, 3 min, 4 min, 5 min, or any value between them. The resulting lithium cobalt oxide cathode material exhibits better capacity and rate performance because an appropriate amount of inert gas helps form an aerosol layer on the material surface, controlling the degree of defect formation during the replacement process, thereby increasing the specific surface area of ​​the material and providing more lithium-ion insertion / extraction channels for the cathode material, which is beneficial to improving the specific capacity and rate performance of the cathode material.

[0051] This invention also provides the application of the above-mentioned lithium cobalt oxide cathode material in lithium-ion batteries. Specifically, this invention provides a lithium-ion battery containing the above-mentioned lithium cobalt oxide cathode material.

[0052] The present invention will be described in detail below through specific embodiments. These embodiments are intended to explain the invention and should not be construed as limiting it. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0053] Preparation Example 1

[0054] This embodiment is used to illustrate the precursor (Co) 0.95 Ni 0.03 Al 0.02 The specific process for preparing 3O4 is as follows:

[0055] S1. Dissolve 58.2g cobalt sulfate (CoSO4·7H2O), 1.72g nickel sulfate (NiSO4·6H2O) and 0.75g aluminum sulfate (Al2(SO4)3) in 1L of deionized water and stir until clear and free of precipitate;

[0056] S2. Prepare another 500 mL of 1.0 M sodium carbonate (Na2CO3) solution as a precipitant;

[0057] S3. At room temperature (25℃), sodium carbonate solution is added dropwise to nickel cobalt aluminum sulfate solution at a rate of 20 mL / min, and the mixture is stirred continuously at a speed of 200 rpm.

[0058] S4. After the addition is complete, continue stirring for 1 hour to produce pink nickel cobalt aluminum carbonate (Co). 0.95 Ni0.03 Al 0.02 CO3) precipitation;

[0059] S5. The precipitate was washed three times by centrifugation with deionized water and then washed once with anhydrous ethanol to remove impurity ions. The precipitate was then dried in an oven at 80°C for 12 hours to obtain the carbonate precursor.

[0060] S6. Place the dried precursor into a muffle furnace, heat it to 700℃ at 5℃ / min in air atmosphere, hold it at that temperature for 3 hours, and after natural cooling, grind it to obtain nickel cobalt aluminum oxide (Co). 0.95 Ni 0.03 Al 0.02 3O4 powder.

[0061] Preparation Example 2

[0062] This embodiment is used to illustrate the precursor (Co) 0.95 Mn 0.03 Mg 0.02 The specific process for preparing 3O4 is as follows:

[0063] S1. Dissolve 58.2g cobalt sulfate (CoSO4·7H2O), 1.11g manganese sulfate (MnSO4·H2O) and 0.53g magnesium sulfate (MgSO4) in 1L of deionized water and stir until clear and free of precipitate;

[0064] S2. Prepare another 500 mL of 1.0 M sodium carbonate (Na2CO3) solution as a precipitant;

[0065] S3. At room temperature (25℃), sodium carbonate solution is added dropwise to nickel cobalt aluminum sulfate solution at a rate of 20 mL / min, and the mixture is stirred continuously at a speed of 200 rpm.

[0066] S4. After the addition is complete, continue stirring for 1 hour to produce pink nickel cobalt aluminum carbonate (Co). 0.95 Mn 0.03 Mg 0.02 CO3) precipitation;

[0067] S5. The precipitate was washed three times by centrifugation with deionized water and then washed once with anhydrous ethanol to remove impurity ions. The precipitate was then dried in an oven at 80°C for 12 hours to obtain the carbonate precursor.

[0068] S6. Place the dried precursor into a muffle furnace, heat it to 700℃ at 5℃ / min in air atmosphere, hold it at that temperature for 3 hours, and after natural cooling, grind it to obtain nickel cobalt aluminum oxide (Co). 0.95 Mn 0.03 Mg 0.02 3O4 powder.

[0069] Preparation Example 3

[0070] This embodiment is used to illustrate the precursor (Co) 0.95 Ni 0.03 Ti 0.02 The specific process for preparing 3O4 is as follows:

[0071] The precursor (Co) was prepared according to the method of Preparation Example 1. 0.95 Ni 0.03 Ti 0.02 The difference is that in step S1, 0.70 g of titanium oxysulfate (TiOSO4) is used instead of 0.75 g of aluminum sulfate (Al2(SO4)3), and all other conditions are the same as in Preparation Example 1. This yields the precursor (Co). 0.95 Ni 0.03 Ti 0.02 )3O4.

[0072] Preparation Example 4

[0073] This embodiment is used to illustrate the precursor (Co) 0.95 Mn 0.03 Y 0.02 The specific process for preparing 3O4 is as follows:

[0074] The precursor (Co) was prepared according to the method of Preparation Example 2. 0.95 Mn 0.03 Y 0.02 The difference is that in step S1, 0.56 g of yttrium nitrate (Y(NO3)3·6H2O) is used instead of 0.53 g of magnesium sulfate (MgSO4), and the other conditions are the same as in preparation example 2. Thus, the precursor (Co) is prepared. 0.95 Mn 0.03 Y 0.02 )3O4.

[0075] Preparation Example 5

[0076] This embodiment is used to illustrate the precursor (Co) 0.95 Ni 0.03 Ca 0.02 The specific process for preparing 3O4 is as follows:

[0077] The precursor (Co) was prepared according to the method of Preparation Example 1. 0.95 Ni 0.03 Ca 0.02 The difference is that in step S1, 0.59 g of calcium sulfate (CaSO4) is used instead of 0.75 g of aluminum sulfate (Al2(SO4)3), while the other conditions are the same as in Preparation Example 1. This yields the precursor (Co). 0.95 Ni 0.03 Ca 0.02 )3O4.

[0078] Preparation Example 6

[0079] This embodiment is used to illustrate the precursor (Co) 0.95 Ni 0.05 The specific process for preparing 3O4 is as follows:

[0080] The precursor (Co) was prepared according to the method of Preparation Example 1. 0.95 Ni 0.05 The difference is that in step S1, 58.2 g of cobalt sulfate (CoSO4·7H2O) and 2.86 g of nickel sulfate (NiSO4·6H2O) are dissolved in 1 L of deionized water, and the other conditions are the same as in Preparation Example 1. This yields the precursor (CoSO4·7H2O). 0.95 Ni 0.05 )3O4.

[0081] Preparation Example 7

[0082] This embodiment is used to illustrate the precursor (Co) 0.95 Al 0.05 The specific process for preparing 3O4 is as follows:

[0083] The precursor (Co) was prepared according to the method of Preparation Example 1. 0.95 Al 0.05 The difference is that in step S1, 58.2 g of cobalt sulfate (CoSO4·7H2O) and 1.86 g of aluminum sulfate (Al2(SO4)3) are dissolved in 1 L of deionized water. All other conditions are the same as in Preparation Example 1, thus preparing the precursor (CoSO4·7H2O). 0.95 Al 0.05 )3O4.

[0084] Example 1

[0085] This embodiment illustrates the preparation of a lithium cobalt oxide cathode material, and the specific process is as follows:

[0086] S1. The precursor (Co) obtained in Example 1 was prepared... 0.95 Ni 0.03 Al 0.02 Co:Na was mixed with 3O4 and sodium hydroxide at a molar ratio of 1:0.75. The mixture was then sintered in a muffle furnace at 900℃ for 48 hours. After sintering, the material was passed through a jaw crusher and sieved to obtain sodium-containing semi-finished material Na. 0.75 Co 0.95 Ni 0.03 Al 0.02 O2;

[0087] S2. A Li-Na hydrothermal replacement reaction was carried out on sodium-containing semi-finished materials. The content of the replacement solids was 40 wt%. In the replacement system, the sodium-containing semi-finished materials Na 0.75 Co 0.95 Ni 0.03 Al 0.02 O2 and Li in solution + The molar ratio is 1:3. The substitution process is as follows: Lithium hydroxide is dissolved in water according to the stoichiometric ratio to prepare the lithium source solution, which is then pumped into a hydrothermal reactor using a peristaltic pump. The hydrothermal reactor is heated from room temperature to 180°C for 2 hours. When the hydrothermal reactor is heated from room temperature to 90°C, sodium-containing semi-finished material is added, and nitrogen gas is introduced into the solution (flow rate 3 L / min, introduction time 3 min). The hydrothermal reactor is then heated to 180°C and subjected to a hydrothermal reaction at this temperature for 4 hours. After the reaction, the temperature is lowered to room temperature, the mixture is discharged, and filtered. After filtration, deionized water is added to wash the solid until the conductivity of the mother liquor is <200 μS / cm. The washed solid material is then vacuum dried at 200°C for 24 hours and sieved through a 325-mesh sieve to obtain the lithium cobalt oxide cathode material, whose general chemical formula is Li. 0.995 Na 0.005 Co 0.95 Ni 0.03 Al 0.02 O2.

[0088] Example 2

[0089] This embodiment illustrates the preparation of a lithium cobalt oxide cathode material, and the specific process is as follows:

[0090] S1. Prepare the precursor (Co) obtained in Example 2. 0.95 Mn 0.03 Mg 0.02 Co:Na was mixed with 3O4 and sodium nitrate at a molar ratio of 1:0.75. The mixture was then sintered in a muffle furnace at 800℃ for 36 hours. After sintering, the material was passed through a jaw crusher and sieved to obtain sodium-containing semi-finished material Na. 0.75 Co 0.95 Mn 0.03 Al 0.02 O2;

[0091] S2. A Li-Na hydrothermal replacement reaction was carried out on sodium-containing semi-finished materials. The content of the replacement solids was 50 wt%. In the replacement system, the sodium-containing semi-finished materials Na 0.75 Co 0.95 Mn 0.03 Mg 0.02 O2 and Li in solution +The molar ratio is 1:3. The substitution process is as follows: Lithium nitrate is dissolved in water according to the stoichiometric ratio to prepare the lithium source solution, which is then pumped into a hydrothermal reactor using a peristaltic pump. The hydrothermal reactor is heated from room temperature to 160°C for 2 hours. When the hydrothermal reactor is heated from room temperature to 80°C, sodium-containing semi-finished material is added, and nitrogen gas is introduced into the solution (flow rate 3 L / min, introduction time 3 min). The hydrothermal reactor is then heated to 160°C and subjected to a hydrothermal reaction at this temperature for 6 hours. After the reaction, the temperature is lowered to room temperature, the mixture is discharged, and filtered. After filtration, deionized water is added to wash the solid until the conductivity of the mother liquor is <200 μS / cm. The washed solid material is then vacuum dried at 200°C for 24 hours and sieved through a 325-mesh sieve to obtain the lithium cobalt oxide cathode material, whose general chemical formula is Li. 0.99 5Na 0.005 Co 0.95 Mn 0.03 Mg 0.02 O2.

[0092] Example 3

[0093] This embodiment illustrates the preparation of a lithium cobalt oxide cathode material, and the specific process is as follows:

[0094] S1. The precursor (Co) obtained in Example 3 was prepared... 0.95 Ni 0.03 Ti 0.02 3O4 and sodium nitrate were mixed at a Co:Na molar ratio of 1:1. The homogeneous mixture was then sintered in a muffle furnace at 1000℃ for 24 hours. After sintering, the material was passed through a jaw crusher and sieved through rollers to obtain the sodium-containing semi-finished material NaCo. 0.95 Ni 0.03 Ti 0.02 O2;

[0095] S2. A Li-Na hydrothermal replacement reaction was carried out on sodium-containing semi-finished materials, with a replacement solid content of 60 wt%. In the replacement system, the sodium-containing semi-finished materials NaCo... 0.95 Ni 0.03 Ti 0.02 O2 and Li in solution +The molar ratio is 1:3. The substitution process is as follows: Lithium nitrate is dissolved in water according to the stoichiometric ratio to prepare the lithium source solution, which is then pumped into a hydrothermal reactor using a peristaltic pump. The hydrothermal reactor is heated from room temperature to 200°C for 2 hours. When the hydrothermal reactor is heated from room temperature to 100°C, sodium-containing semi-finished material is added, and nitrogen gas is introduced into the solution (flow rate 4 L / min, introduction time 3 min). The hydrothermal reactor is then heated to 200°C and subjected to a hydrothermal reaction at this temperature for 2 hours. After the reaction, the temperature is lowered to room temperature, the mixture is discharged, and filtered. After filtration, deionized water is added to wash the solid until the conductivity of the mother liquor is <200 μS / cm. The washed solid material is then vacuum dried at 200°C for 24 hours and sieved through a 325-mesh sieve to obtain the lithium cobalt oxide cathode material, whose general chemical formula is Li. 0.995 Na 0.005 Co 0.95 Ni 0.03 Ti 0.02 O2.

[0096] Example 4

[0097] This embodiment illustrates the preparation of a lithium cobalt oxide cathode material, and the specific process is as follows:

[0098] Lithium cobalt oxide cathode material was prepared according to the method of Example 2, except that the precursor (Co) obtained in Example 4 was used in step S1. 0.95 Mn 0.03 Y 0.02 Li3O4 and sodium hydroxide were mixed in a Co:Na molar ratio of 1:0.75, and all other conditions were the same as in Example 2. This yielded a lithium cobalt oxide cathode material with the chemical formula Li. 0.995 Na 0.005 Co 0.95 Mn 0.03 Y 0.02 O2.

[0099] Example 5

[0100] This embodiment illustrates the preparation of a lithium cobalt oxide cathode material, and the specific process is as follows:

[0101] Lithium cobalt oxide cathode materials were prepared according to the method of Example 1, except that the precursor (Co) obtained in Example 5 was used in step S1. 0.95 Ni 0.03 Ca 0.02 Li3O4 and sodium hydroxide were mixed in a Co:Na molar ratio of 1:0.75, and all other conditions were the same as in Example 1. This yielded a lithium cobalt oxide cathode material with the chemical formula Li. 0.995 Na 0.005 Co 0.95Ni 0.03 Ca 0.02 O2.

[0102] Example 6

[0103] This embodiment illustrates the preparation of a lithium cobalt oxide cathode material, and the specific process is as follows:

[0104] Lithium cobalt oxide cathode material was prepared according to the method of Example 1, except that in step S1, the precursor Co3O4 and sodium hydroxide were mixed in a Co:Na molar ratio of 1:0.75. All other conditions were the same as in Example 1. The resulting lithium cobalt oxide cathode material has the chemical formula Li. 0.995 Na 0.005 CoO2.

[0105] Example 7

[0106] This embodiment illustrates the preparation of a lithium cobalt oxide cathode material, and the specific process is as follows:

[0107] Lithium cobalt oxide cathode material was prepared according to the method of Example 1, except that in step S2, the lithium source solution was first mixed with sodium-containing semi-finished material, pumped into a hydrothermal reactor using a peristaltic pump, and nitrogen gas was introduced. Then, the hydrothermal reactor was heated from room temperature to 180°C, while the remaining conditions were the same as in Example 1. This yielded lithium cobalt oxide cathode material with the general chemical formula Li. 0.99 Na 0.01 Co 0.95 Ni 0.03 Al 0.02 O2.

[0108] Example 8

[0109] This embodiment illustrates the preparation of a lithium cobalt oxide cathode material, and the specific process is as follows:

[0110] Lithium cobalt oxide cathode materials were prepared according to the method of Example 1, except that the precursor (Co) obtained in Example 6 was used in step S1. 0.95 Ni 0.05 Li3O4 and sodium hydroxide were mixed in a Co:Na molar ratio of 1:0.75, and all other conditions were the same as in Example 1. This yielded a lithium cobalt oxide cathode material with the chemical formula Li. 0.995 Na 0.005 Co 0.95 Ni 0.05 O2.

[0111] Example 9

[0112] This embodiment illustrates the preparation of a lithium cobalt oxide cathode material, and the specific process is as follows:

[0113] Lithium cobalt oxide cathode materials were prepared according to the method of Example 1, except that the precursor (Co) obtained in Example 7 was used in step S1. 0.95 Al 0.05 Li3O4 and sodium hydroxide were mixed in a Co:Na molar ratio of 1:0.75, and all other conditions were the same as in Example 1. This yielded a lithium cobalt oxide cathode material with the chemical formula Li. 0.995 Na 0.005 Co 0.95 Al 0.05 O2.

[0114] Comparative Example 1

[0115] This comparative example illustrates the preparation of a reference lithium cobalt oxide cathode material, and the specific process is as follows:

[0116] The reference lithium cobalt oxide cathode material was prepared according to the method of Example 1. The difference was that in step S2, nitrogen gas was not introduced when the sodium-containing semi-finished material was added to the hydrothermal reactor. All other conditions were the same as in Example 1. The reference lithium cobalt oxide cathode material was thus prepared.

[0117] Comparative Example 2

[0118] This comparative example illustrates the preparation of a reference lithium cobalt oxide cathode material, and the specific process is as follows:

[0119] Precursor (Co) 0.95 Ni 0.03 Al 0.02 3O4 and lithium hydroxide were mixed in a Co:Li molar ratio of 1:1.05. The mixture was then placed in a muffle furnace for sintering at a temperature of 900℃ for 48 hours. After sintering, the material was sieved through a jaw crusher to obtain a reference lithium cobalt oxide cathode material.

[0120] Test case

[0121] This test example is used to illustrate the relevant performance of the lithium cobalt oxide cathode materials prepared by the above examples and comparative examples. The results are shown in Table 1 and Table 2.

[0122] 1. Microstructure testing

[0123] (1) D50 particle size test: A laser particle size analyzer (Malvern Mastersizer 3000) was used. The dispersion medium was deionized water and the dispersant was 0.5% sodium hexametaphosphate (NaPO3)6 (to prevent particle agglomeration).

[0124] The testing steps are as follows:

[0125] a. Take about 50 mg of sample and add it to 50 mL of dispersion medium. Disperse by ultrasonication for 5 to 10 min (power 200 W, frequency 40 kHz).

[0126] b. Inject the dispersed suspension into the instrument's sample cell and perform background calibration before testing.

[0127] c. Set the refractive index (1.52) and absorptivity (0.1) to activate the dynamic light scattering (DLS) mode.

[0128] d. Repeat the test 3 times and take the average value as the final result.

[0129] (2) Specific surface area test: The specific surface area was tested using a Micromeritics ASAP 2460 analyzer. The test steps are as follows: a. Take 100-200 mg of sample and degas it under vacuum at 120℃ for 4 h to remove surface adsorbates; b. At liquid nitrogen temperature (77 K), the N2 adsorption-desorption isotherm was obtained and the BET specific surface area was calculated (relative pressure P / P0 range: 0.05-0.3).

[0130] (3) True density test: The test was conducted using a helium specific gravity meter (AccuPyc II 1340). The test method is as follows: a. Weigh 5-10g of dry sample and place it in the sample cell, then introduce high-purity helium (99.999%) to remove pore gas; b. Measure the volume using the gas displacement method and calculate the true density (repeat 3 times and take the average value).

[0131] (4) Tap density test: The tap density meter (Hosokawa PT-E) was used for the test. The test method is as follows: a. Take a 50mL graduated cylinder and put 20g of sample into it. The initial volume is recorded as V0; b. Vibrate at a frequency of 250 times / min for 500 times and record the volume after tapping V1. c. Tap density = mass (20g) / V1.

[0132] (5) XRD testing: X-ray diffractometer (Bruker D8 Advance) was used for testing. Parameter conditions: Target material was Cu Kα. The voltage was 40 kV, the current was 40 mA, the scanning range was 10–80° (2θ), the step size was 0.02°, and the scanning speed was 5° / min. The peak intensity ratio I(003) / I(104) of the 003 peak and the 104 peak was calculated based on the obtained XRD spectrum data.

[0133] 2. Electrochemical performance testing

[0134] (1) Preparation of button cell: Lithium cobalt oxide cathode material, acetylene black, and polyvinylidene fluoride (PVDF) were weighed and mixed in a mass ratio of 90:5:5. The viscosity of the slurry was controlled to be 8000 mPa·s in a degassing machine. Then, the slurry was uniformly coated onto aluminum foil using an automatic coating machine to form the original electrode sheet. The electrode sheet was dried in a vacuum oven at 130°C for 4 hours and then placed in a forced-air oven at 80°C for 12 hours to obtain the test sheet. Several small electrode sheets were cut from different positions of the test sheet using a punch die with a diameter of 14 mm. The small electrode sheets with regular shape, smooth surface and edges were selected. The small electrode pieces were weighed using a balance with a weight of 0.0001 g / L. The weighed small electrode pieces were placed in a vacuum drying oven and evacuated to 0.1 MPa to obtain the positive electrode piece, which was then stored for later use. In an inert gas glove box with water and oxygen content of less than or equal to 0.0005%, coin cells were assembled according to the battery specifications of CR2023. The negative electrode was a lithium sheet, the separator was a polypropylene membrane, the high-voltage electrolyte solvent was a mixed solution of ethylene carbonate and diethyl carbonate with a volume ratio of 1:1, and the conductive salt was 1M lithium hexafluorophosphate. After assembly, the cells were encapsulated at 800 Pa for 5 seconds to obtain a coin cell.

[0135] (2) Charge and discharge performance test: The coin cell assembled according to the method in (1) was charged at a constant current of 0.1C to a voltage of 4.6V under normal temperature battery laboratory conditions, and then charged at a constant voltage of 4.6V to a current of 0.05C. After standing for 5 minutes, the charging capacity was recorded. Then the coin cell was discharged at a constant current of 0.1C to a voltage of 3.0V, and the discharge capacity was recorded. The first charge specific capacity and the first coulombic efficiency at 0.1C were calculated (first efficiency = discharge capacity / charge capacity * 100%).

[0136] (3) Rate performance test: The coin cell assembled according to the method in (1) is charged at a constant current of 0.5C to a voltage of 4.6V under normal temperature battery laboratory conditions, and then charged at a constant voltage of 4.6V to a current of 0.05C. After standing for 5 minutes, the charging capacity is recorded. Then the coin cell is discharged at a constant current of 0.5C to a voltage of 3.0V, and the discharge capacity is recorded. The discharge capacity at 0.5C is calculated, and the ratio of the discharge capacity at 0.5C to the initial discharge capacity at 0.1C is calculated.

[0137] (4) The button cell assembled according to the method in (1) is subjected to 50 charge-discharge cycles at a constant current of 1C in a voltage range of 3.0 to 4.6V under normal temperature battery laboratory conditions, and the capacity retention rate of the battery before and after the cycle is calculated.

[0138] Table 1

[0139]

[0140]

[0141] Table 2

[0142]

[0143] As shown in Table 1, compared to Comparative Examples 1 and 2, when the D50 particle size of the lithium cobalt oxide cathode material is similar, the lithium cobalt oxide cathode materials obtained in Examples 1-9 of this invention have a more suitable specific surface area, true density, tap density, and a higher I(003) / I(104) ratio. As shown in Table 2, compared to Comparative Examples 1 and 2, the lithium cobalt oxide cathode materials obtained in Examples 1-9 of this invention have higher charge specific capacity performance, 0.5C / 0.1C reversible specific capacity retention rate, and cycle retention rate.

[0144] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A lithium cobalt oxide cathode material, characterized in that, When the D50 particle size of the lithium cobalt oxide cathode material is 10 - 20 μm, its specific surface area is 0.5 - 0.7 m y / g; the true density of the lithium cobalt oxide cathode material is 4.85 - 5.03 g / cm 3 , and the tapped density is 2.35 - 2.50 g / cm 3 ; the lithium cobalt oxide cathode material has a R3 - m space group structure, and the intensity ratio I(003) / I(104) of the 003 peak and the 104 peak in the XRD pattern of the lithium cobalt oxide cathode material is 2.5 - 3.8; the chemical general formula of the lithium cobalt oxide cathode material is Li y Na z Co 1-a-b A a M b O2, where 0.93 ≤ y ≤ 1.02, 0 < z ≤ 0.02, 0 < a ≤ 0.1, 0 < b ≤ 0.05, A is selected from Ni and / or Mn, and M is selected from at least one of Al, Mg, Ti, Tc, Mo, Ca, W, Nb, Zr, La, Y; the preparation method of the lithium cobalt oxide cathode material includes the following steps: S1. The lithium cobalt oxide cathode material precursor is mixed with a sodium source, and the resulting mixture is sintered to obtain a sodium-containing semi-finished material. S2. After mixing sodium-containing semi-finished material with lithium source, inert gas is introduced to form aerosol. Then, the reaction system is subjected to hydrothermal reaction. The hydrothermal reaction is carried out under the protection of aerosol formed by inert gas. After the reaction is completed, solid-liquid separation, water washing and drying are performed. The resulting solid product is lithium cobalt oxide cathode material. In step S1, the lithium cobaltate cathode material precursor has a structure shown by (Co 1-a-b A a M b )3O4 and / or Co 1-a-b A a M b (OH)2, where 0 < a ≤ 0.1, 0 < b ≤ 0.05, A is selected from Ni and / or Mn, and M is selected from at least one of Al, Mg, Ti, Tc, Mo, Ca, W, Nb, Zr, La, and Y; In step S2, the process of mixing the sodium-containing semi-finished material with the lithium source and then introducing an inert gas to form an aerosol includes: mixing the lithium source and water to obtain a lithium source solution; first heating the reaction system containing the lithium source solution to 80~100℃; then adding the sodium-containing semi-finished material and introducing an inert gas into the reaction system to form an aerosol; the amount of inert gas introduced is based on ensuring that the pressure of the reaction system is 0.3~2.0MPa.

2. The lithium cobalt oxide cathode material according to claim 1, characterized in that, In the XRD spectrum of the lithium cobalt oxide cathode material, the 2θ value of the 003 peak is 18.7~19.2°, and the 2θ value of the 104 peak is 45.0~45.5°.

3. The lithium cobalt oxide cathode material according to claim 1, characterized in that, M is selected from at least one of Al, Ti, Y, and Mg.

4. The lithium cobalt oxide cathode material according to claim 1, characterized in that, The Na content in the lithium cobalt oxide cathode material is less than 500 ppm.

5. A method for preparing a lithium cobalt oxide cathode material, characterized in that, The method includes the following steps: S1. The lithium cobalt oxide cathode material precursor is mixed with a sodium source, and the resulting mixture is sintered to obtain a sodium-containing semi-finished material. S2. After mixing sodium-containing semi-finished material with lithium source, inert gas is introduced to form aerosol. Then, the reaction system is subjected to hydrothermal reaction. The hydrothermal reaction is carried out under the protection of aerosol formed by inert gas. After the reaction is completed, solid-liquid separation, water washing and drying are performed. The resulting solid product is lithium cobalt oxide cathode material. In step S1, the lithium cobaltate cathode material precursor has a structure represented by (Co 1-a-b A a M b )3O4 and / or Co 1-a-b A a M b (OH)2, where 0 < a ≤ 0.1, 0 < b ≤ 0.05, A is selected from Ni and / or Mn, and M is selected from at least one of Al, Mg, Ti, Tc, Mo, Ca, W, Nb, Zr, La, and Y; In step S2, the process of mixing the sodium-containing semi-finished material with the lithium source and then introducing an inert gas to form an aerosol includes: mixing the lithium source and water to obtain a lithium source solution; first heating the reaction system containing the lithium source solution to 80~100℃; then adding the sodium-containing semi-finished material and introducing an inert gas into the reaction system to form an aerosol; the amount of inert gas introduced is based on ensuring that the pressure of the reaction system is 0.3~2.0MPa.

6. The method for preparing the lithium cobalt oxide cathode material according to claim 5, characterized in that, M is selected from at least one of Al, Mg, Ti, and Y.

7. The method for preparing the lithium cobalt oxide cathode material according to claim 5, characterized in that, The sodium source is selected from at least one of sodium carbonate, sodium hydroxide, sodium bicarbonate, sodium nitrate, sodium sulfate, sodium acetate, and sodium oxalate.

8. The method for preparing the lithium cobalt oxide cathode material according to claim 5, characterized in that, The molar ratio of Co to Na in the sodium source in the lithium cobalt oxide cathode material is 1:(0.75~1.20).

9. The method for preparing the lithium cobalt oxide cathode material according to claim 5, characterized in that, The sintering process is carried out at a temperature of 700~1000℃ for 16~48h.

10. The method for preparing the lithium cobalt oxide cathode material according to claim 5, characterized in that, Step S2, wherein the lithium source is selected from at least one of lithium hydroxide, lithium nitrate, lithium carbonate, lithium chloride, lithium bromide and lithium iodide.

11. The method for preparing the lithium cobalt oxide cathode material according to claim 5, characterized in that, The molar ratio of Na to Li in the lithium source in the sodium-containing semi-finished material is 1:(1~4).

12. The method for preparing the lithium cobalt oxide cathode material according to claim 5, characterized in that, The conditions for the hydrothermal reaction include a temperature of 160~200℃ and a time of 2~6h.

13. The method for preparing the lithium cobalt oxide cathode material according to claim 5, characterized in that, The solid content of the reaction system during the hydrothermal reaction is 40~60wt%.

14. The method for preparing the lithium cobalt oxide cathode material according to claim 5, characterized in that, The inert gas is selected from at least one of nitrogen, neon, argon, xenon, and radon.

15. The method for preparing the lithium cobalt oxide cathode material according to claim 5, characterized in that, The inert gas is introduced at a flow rate of 2-5 L / min for 1-5 min.

16. A lithium cobalt oxide cathode material prepared by the method according to any one of claims 5 to 15.

17. The application of the lithium cobalt oxide cathode material according to any one of claims 1 to 4 and 16 in lithium-ion batteries.

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