A lithium cobalt oxide positive electrode material, a preparation method thereof, a positive electrode sheet, and a battery
By introducing carbon into the lithium cobalt oxide cathode material and performing ball milling and carbon coating processes, the problems of insufficient discharge capacity and impedance growth at low temperatures were solved, resulting in improved high conductivity and stability of the material.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HIGHPOWER TECH HUIZHOU
- Filing Date
- 2023-06-27
- Publication Date
- 2026-06-12
AI Technical Summary
Existing lithium cobalt oxide cathode materials have insufficient discharge capacity at low temperatures and significant impedance growth during cycling, which affects the performance of battery cell products.
Cobalt tetroxide powder doped with carbon was prepared by ball milling and sintering cobalt carbonate and carbon source, and then mixed with lithium salt, ball milled and calcined, and finally carbon coated to form carbon-coated lithium cobalt oxide, which improves the conductivity of the material and blocks the side reactions between the cathode material and the electrolyte.
This improved the low-temperature discharge capability and cycle life of lithium cobalt oxide cathode materials, reduced the impedance during initial and cycling processes, and enhanced the conductivity and stability of the materials.
Smart Images
Figure CN116715278B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of battery technology, specifically relating to a lithium cobalt oxide cathode material and its preparation method, cathode sheet, and battery. Background Technology
[0002] Lithium-ion batteries, as high-energy-density chemical power sources, are widely used in mobile communications, laptops, camcorders, cameras, portable instruments, and other fields. They are also the preferred power source for electric vehicles and space power, which are being heavily researched by various countries, making them a top choice for alternative energy sources. Lithium cobalt oxide, a commonly used cathode material in the consumer electronics industry, plays a crucial role in battery cell development. However, a common problem in the development of lithium cobalt oxide is its high material impedance, which has somewhat hampered the development of battery cell products. With the diversification of application scenarios in the 3C field and the increasing demand for long-life products, how to increase the discharge capacity at low temperatures and reduce the impedance growth during cycling are issues of great concern. Summary of the Invention
[0003] To address the issues of increasing discharge capacity at low temperatures and reducing impedance growth during cycling, this invention provides a lithium cobalt oxide cathode material, its preparation method, cathode sheet, and battery.
[0004] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:
[0005] On one hand, the present invention provides a method for preparing lithium cobalt oxide cathode material, comprising the following steps:
[0006] To obtain cobalt carbonate with a particle size of 18-20 μm;
[0007] Cobalt carbonate with a particle size of 18-20 μm and carbon source A were mixed, ball-milled, sintered, and calcined to obtain carbon-doped cobalt tetroxide powder.
[0008] Carbon-doped cobalt tetroxide powder was mixed with lithium salt, ball-milled, sintered, pulverized, and calcined to obtain carbon-doped lithium cobalt oxide.
[0009] Carbon source B, carbon-doped lithium cobalt oxide, and dispersant were mixed and then subjected to wet ball milling.
[0010] The mixture after wet ball milling is calcined by passing a protective gas through it, and the sintered material is then crushed and sieved to obtain carbon-coated lithium cobalt oxide.
[0011] Optionally, carbon source A includes one or more of fructose, sucrose, tartaric acid, glucose, gluconic acid, and cellobiose; carbon source B includes one or more of polyvinyl alcohol, polyacryl alcohol, phenolic resin, and polyvinyl alcohol.
[0012] Optionally, based on the mass of the carbon-coated lithium cobalt oxide as 100%, the content of carbon source A in the carbon-coated lithium cobalt oxide is 0.2-0.5%, and the content of carbon source B in the carbon-coated lithium cobalt oxide is 1-3%.
[0013] Optionally, the preparation method of cobalt carbonate with a particle size of 18-20 μm is as follows: prepare a cobalt sulfate solution and an ammonium bicarbonate solution to synthesize cobalt carbonate with a particle size of 7-9 μm; prepare a cobalt sulfate solution and an ammonium bicarbonate solution, and use cobalt carbonate with a particle size of 7-9 μm as crystal nuclei to synthesize cobalt carbonate with a particle size of 18-20 μm.
[0014] Optionally, the concentration of the cobalt sulfate solution is 1.5-1.8 mol / L, and the concentration of the ammonium bicarbonate solution is 2.1-2.5 mol / L.
[0015] Optionally, in the process of preparing cobalt carbonate with a particle size of 7-9 μm, the pH of the reaction solution is controlled at 7.2±0.2, the reaction temperature at 20-25℃, and the stirring speed at 580-600 r / min; when the particle size of cobalt carbonate is between 9-20 μm, the pH of the reaction solution is controlled at 7.2±0.2, the reaction temperature at 30-35℃, and the stirring speed at 480-500 r / min.
[0016] Optionally, when mixing carbon-doped cobalt tetroxide powder with lithium salt, the ball milling speed is 400-420 r / min, the ball milling time is 6-7 h, the particle size of the ball milling beads is 11-12 mm, the total mass ratio of carbon-doped cobalt tetroxide powder and lithium salt to the mass ratio of ball milling beads is 1:15, and the mass ratio of carbon-doped cobalt tetroxide powder to lithium salt is 1:(1.06-1.1).
[0017] Optionally, in the step of preparing cobalt tetroxide powder, the sintering and calcination temperature is 480-500℃, and the holding time is 9-10h;
[0018] In the step of preparing carbon-doped lithium cobalt oxide, the sintering and calcination temperature is 880-900℃, and the holding time is 11-12h;
[0019] In the step of preparing carbon-coated lithium cobalt oxide, the calcination temperature is 280-300℃, the sintering temperature is 380-400℃, and the holding time is 4-6h.
[0020] On the other hand, the present invention provides a cathode material prepared by the method for preparing lithium cobalt oxide cathode material as described in any one of the above claims.
[0021] On the other hand, the present invention provides a positive electrode sheet comprising the lithium cobalt oxide positive electrode material as described in any of the above claims, or the lithium cobalt oxide positive electrode material prepared by the preparation method of the lithium cobalt oxide positive electrode material as described in any of the above claims.
[0022] On the other hand, the present invention provides a battery comprising a positive electrode as described above.
[0023] In this invention, cobalt carbonate and carbon source A are mixed, ball-milled, and sintered to introduce carbon into the lattice and grain boundaries of lithium cobalt oxide, thereby improving the conductivity of the material from a bulk perspective. Simultaneously, carbon source B and carbon-doped lithium cobalt oxide are ball-milled to carbon-coat the lithium cobalt oxide. This further enhances the carbon modification process, allowing it to encapsulate the lithium cobalt oxide. This increases the material's conductivity while simultaneously blocking side reactions between the cathode material and the electrolyte. This reduces the initial and cycling impedance of the cathode material, thereby improving low-temperature discharge capability and cycle life. Attached Figure Description
[0024] Figure 1 This is a SEM image of the lithium cobalt oxide cathode material prepared in Example 1 of the present invention;
[0025] Figure 2 This is a SEM image of the lithium cobalt oxide cathode material prepared in Comparative Example 1 of the present invention;
[0026] Figure 3 The images show the XRD patterns of the lithium cobalt oxide cathode materials prepared in Example 1 and Comparative Example 1 of this invention.
[0027] Figure 4 The high-temperature cycling curves of the batteries prepared in Example 1 and Comparative Example 1 of the present invention are shown.
[0028] Figure 5 This is a graph showing the impedance growth before and after cycling of the batteries prepared in Example 1 and Comparative Example 1 of the present invention. Detailed Implementation
[0029] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
[0030] An embodiment of the present invention provides a method for preparing a lithium cobalt oxide cathode material, comprising the following steps:
[0031] To obtain cobalt carbonate with a particle size of 18-20 μm;
[0032] Cobalt carbonate with a particle size of 18-20 μm and carbon source A were mixed, ball-milled, sintered, and calcined to obtain carbon-doped cobalt tetroxide powder.
[0033] Carbon-doped cobalt tetroxide powder was mixed with lithium salt, ball-milled, sintered, pulverized, and calcined to obtain carbon-doped lithium cobalt oxide.
[0034] The carbon source B, carbon-doped lithium cobalt oxide, and dispersant are mixed and then wet ball-milled; specifically, the dispersant is sodium dodecylbenzenesulfonate.
[0035] The mixture after wet ball milling is calcined under a protective gas, and the sintered material is then pulverized and sieved to obtain carbon-coated lithium cobalt oxide. Specifically, the pulverization process includes jaw crusher, roller mill, and air jet milling. The protective gas includes one or more of nitrogen, argon, and helium.
[0036] In this invention, cobalt carbonate and carbon source A are mixed, ball-milled, and sintered to introduce carbon into the lattice and grain boundaries of lithium cobalt oxide, thereby improving the conductivity of the material from a bulk perspective. Simultaneously, carbon source B and carbon-doped lithium cobalt oxide are ball-milled to carbon-coat the lithium cobalt oxide. This further enhances the carbon modification process, allowing it to encapsulate the lithium cobalt oxide. This increases the material's conductivity while simultaneously blocking side reactions between the cathode material and the electrolyte. This reduces the initial and cycling impedance of the cathode material, thereby improving low-temperature discharge capability and cycle life.
[0037] In some embodiments, carbon source A includes one or more of fructose, sucrose, tartaric acid, glucose, gluconic acid, and cellobiose. Carbon source B includes one or more of polyvinyl alcohol, polyacryl alcohol, phenolic resin, and polyvinyl alcohol. Carbon source A is a small organic molecule carbon source, which is small in size and easy to introduce into the grain boundaries and lattice of lithium cobalt oxide. Carbon source B is an organic polymer carbon source, which stabilizes the interface between lithium cobalt oxide and the electrolyte, while increasing the conductivity of lithium cobalt oxide.
[0038] In some embodiments, based on the mass of the carbon-coated lithium cobalt oxide as 100%, the content of carbon source A in the carbon-coated lithium cobalt oxide is 0.2-0.5%, and the content of carbon source B in the carbon-coated lithium cobalt oxide is 1-3%.
[0039] In one specific embodiment, the content of carbon source A in the carbon-coated lithium cobalt oxide is 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%. The content of carbon source B in the carbon-coated lithium cobalt oxide is 1%, 1.5%, 2%, 2.5%, or 3%.
[0040] In some embodiments, the method for preparing cobalt carbonate with a particle size of 18-20 μm is as follows: preparing a cobalt sulfate solution and an ammonium bicarbonate solution to synthesize cobalt carbonate with a particle size of 7-9 μm; preparing a cobalt sulfate solution and an ammonium bicarbonate solution, using cobalt carbonate with a particle size of 7-9 μm as crystal nuclei, to synthesize cobalt carbonate with a particle size of 18-20 μm.
[0041] In some embodiments, the concentration of the cobalt sulfate solution is 1.5-1.8 mol / L, and the concentration of the ammonium bicarbonate solution is 2.1-2.5 mol / L. Specifically, the concentration of the cobalt sulfate solution is 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, or 1.8 mol / L. The concentration of the ammonium bicarbonate solution is 2.1 mol / L, 2.2 mol / L, 2.3 mol / L, 2.4 mol / L, or 2.5 mol / L.
[0042] In some embodiments, during the preparation of cobalt carbonate with a particle size of 7-9 μm, the pH of the reaction solution is controlled at 7.2 ± 0.2, the reaction temperature at 20-25 °C, and the stirring speed at 580-600 r / min; when the cobalt carbonate particle size is between 9-20 μm, the pH of the reaction solution is controlled at 7.2 ± 0.2, the reaction temperature at 30-35 °C, and the stirring speed at 480-500 r / min. Specifically, the pH value of the solution is controlled by a pH adjuster, which includes an acid solution, an alkaline solution, or a buffer solution.
[0043] In some embodiments, when carbon-doped cobalt tetroxide powder is mixed with lithium salt, the ball milling speed is 400-420 r / min, the ball milling time is 6-7 h, the particle size of the ball milling beads is 11-12 mm, the total mass ratio of carbon-doped cobalt tetroxide powder and lithium salt to the mass ratio of ball milling beads is 1:15, and the mass ratio of carbon-doped cobalt tetroxide powder to lithium salt is 1:(1.06-1.1).
[0044] In some embodiments, in the step of preparing cobalt tetroxide powder, the sintering and calcination temperature is 480-500℃, and the holding time is 9-10h.
[0045] In the step of preparing carbon-doped lithium cobalt oxide, the sintering and calcination temperature is 880-900℃, and the holding time is 11-12h.
[0046] In the step of preparing carbon-coated lithium cobalt oxide, the calcination temperature is 280-300℃, the sintering temperature is 380-400℃, and the holding time is 4-6h.
[0047] On the other hand, one embodiment of the present invention provides a cathode material prepared by the method for preparing lithium cobalt oxide cathode material described in any of the above embodiments.
[0048] On the other hand, one embodiment of the present invention provides a positive electrode sheet, comprising the lithium cobalt oxide positive electrode material as described in any of the above claims, or the lithium cobalt oxide positive electrode material prepared by the preparation method of the lithium cobalt oxide positive electrode material as described in any of the above claims.
[0049] On the other hand, one embodiment of the present invention provides a battery including the positive electrode plate as described above. The present invention will be further described below through embodiments.
[0050] Example 1
[0051] This embodiment illustrates the lithium cobalt oxide cathode material and its preparation method disclosed in this invention, including the following steps:
[0052] A cobalt sulfate solution with a concentration of 1.5 mol / L and an ammonium bicarbonate solution with a concentration of 2.1 mol / L were used to synthesize cobalt carbonate particles of 8 μm as crystal nuclei. Before the particle size reached 8 μm, the reaction was controlled at pH 7.2 ± 0.2, reaction temperature 25℃, and stirring speed 600 r / min. When the particle size was between 8 and 20 μm, the reaction was controlled at pH 7.2 ± 0.2, reaction temperature 35℃, and stirring speed 500 r / min.
[0053] The prepared 18μm cobalt carbonate was mixed with fructose and sucrose, ball-milled, calcined at 500℃ and kept at that temperature for 10h to obtain carbon-doped cobalt tetroxide powder.
[0054] Carbon-doped cobalt tetroxide powder was mixed with lithium salt at a mass ratio of 1:1.06, and then calcined at 900℃ for 12 hours to prepare carbon-doped lithium cobalt oxide.
[0055] Polyacryl alcohol, phenolic resin, carbon-doped lithium cobalt oxide, and sodium dodecylbenzenesulfonate (dispersant) are mixed and wet-milled in a planetary ball mill. After calcination at 300°C with argon gas for 4-6 hours, the mixture is then crushed by a jaw crusher and roller mill, and sieved to obtain carbon-coated lithium cobalt oxide. The inlet pressure is 0.1-3 MPa; the gap between the jaw crusher and roller mill is 0.1-0.3 mm; the airflow pulverization frequency is 50-100 Hz; and the classification frequency is 10-150 Hz. The carbon source A content in the carbon-coated lithium cobalt oxide is 0.5%, and the carbon source B content is 3%.
[0056] Example 2
[0057] This embodiment illustrates the lithium cobalt oxide cathode material and its preparation method disclosed in this invention, including most of the operational steps in Example 1, with the following differences:
[0058] The steps for preparing cobalt carbonate with a particle size of 18-20 μm are as follows: the concentration of cobalt sulfate solution is prepared to be 1.5 mol / L, the concentration of ammonium bicarbonate solution is prepared to be 2.1 mol / L, the pH of the reaction process is controlled to be 7.2±0.2, the reaction temperature is 35℃, and the stirring speed is 500 r / min.
[0059] Example 3
[0060] This embodiment is used to illustrate the lithium cobalt oxide cathode material and its preparation method disclosed in this invention, including most of the operation steps in Example 1, except that the content of carbon source A in the carbon-coated lithium cobalt oxide is 0.2%.
[0061] Example 4
[0062] This embodiment is used to illustrate the lithium cobalt oxide cathode material and its preparation method disclosed in this invention, including most of the operation steps in Example 1, except that the content of carbon source A in the carbon-coated lithium cobalt oxide is 0.05%.
[0063] Example 5
[0064] This embodiment is used to illustrate the lithium cobalt oxide cathode material and its preparation method disclosed in this invention, including most of the operation steps in Example 1, except that the content of carbon source A in the carbon-coated lithium cobalt oxide is 1%.
[0065] Example 6
[0066] This embodiment is used to illustrate the lithium cobalt oxide cathode material and its preparation method disclosed in this invention, including most of the operation steps in Example 1, except that the content of carbon source B in the carbon-coated lithium cobalt oxide is 1%.
[0067] Example 7
[0068] This embodiment is used to illustrate the lithium cobalt oxide cathode material and its preparation method disclosed in this invention, including most of the operation steps in Example 1, except that the content of carbon source B in the carbon-coated lithium cobalt oxide is 0.5%.
[0069] Example 8
[0070] This embodiment is used to illustrate the lithium cobalt oxide cathode material and its preparation method disclosed in this invention, including most of the operation steps in Example 1, except that the content of carbon source B in the carbon-coated lithium cobalt oxide is 5%.
[0071] Example 9
[0072] This embodiment is used to illustrate the lithium cobalt oxide cathode material and its preparation method disclosed in this invention, including most of the operation steps in Example 1, except that the carbon source A is carbon nanotubes.
[0073] Example 10
[0074] This embodiment is used to illustrate the lithium cobalt oxide cathode material and its preparation method disclosed in this invention, including most of the operation steps in Example 1, except that the carbon source B is carbon nanotubes.
[0075] Comparative Example 1
[0076] This comparative example is used to illustrate the lithium cobalt oxide cathode material and its preparation method disclosed in this invention. It includes most of the operation steps in Example 1, except that carbon source A and carbon source B are not added, carbon is not doped into lithium cobalt oxide, and a coating layer is not formed on the surface of lithium cobalt oxide.
[0077] Comparative Example 2
[0078] This comparative example is used to illustrate the lithium cobalt oxide cathode material and its preparation method disclosed in this invention. It includes most of the operation steps in Example 1, except that carbon source A was not added and carbon was not doped into the lithium cobalt oxide.
[0079] Comparative Example 3
[0080] This comparative example is used to illustrate the lithium cobalt oxide cathode material and its preparation method disclosed in this invention. It includes most of the operation steps in Example 1, except that carbon source B was not added to form a carbon coating layer.
[0081] Comparative Example 4
[0082] This comparative example is used to illustrate the lithium cobalt oxide cathode material and its preparation method disclosed in this invention. It includes most of the operational steps in Example 1, with the difference being: in the step of preparing cobalt tetroxide, the concentration of cobalt sulfate solution is 1.5 mol / L, the concentration of ammonium bicarbonate is 2.1 mol / L, and cobalt carbonate particles of 8 μm are synthesized as crystal nuclei. Before the particle size reaches 8 μm, the reaction process is controlled at pH 7.2 ± 0.2, the reaction temperature is 25 °C, and the stirring speed is 600 r / min. In the step of preparing cobalt sulfate solution, the concentration is 1.5 mol / L, the concentration of ammonium bicarbonate is 2.1 mol / L, and the concentration of aluminum chloride is 0.06-0.08 mol / L. When the particle size is between 8-20 μm, the reaction process is controlled at pH 7.2 ± 0.2, the reaction temperature is 35 °C, and the stirring speed is 500 r / min.
[0083] The prepared 18μm aluminum-doped cobalt carbonate was calcined at 500℃ and held at that temperature for 10h to obtain aluminum-doped cobalt tetroxide powder.
[0084] Performance testing
[0085] I. The lithium cobalt oxide cathode materials prepared in Example 1 and Comparative Example 1 were subjected to composition scanning, and the resulting SEM images are shown below. Figure 1 and Figure 2 As shown.
[0086] XRD was performed on the lithium cobalt oxide cathode materials prepared in Example 1 and Comparative Example 1, and the results are as follows: Figure 3 As shown in the figure. By comparing the XRD data, it was found that the lithium cobalt oxide under carbon coating modification did not undergo a change in crystal form, which confirms that this modification method did not affect the overall structure of lithium cobalt oxide.
[0087] 2. The lithium cobalt oxide cathode materials, conductive carbon black, and PVDF prepared in Examples 1-10 and Comparative Examples 1-4 were mixed evenly in a mass ratio of 8:1:1. This mixture was then uniformly coated onto aluminum foil and dried for 12 hours before being cut into regular circular pieces for later use. The assembly process was carried out in an argon-filled glove box (water and oxygen levels were both less than 0.1 ppm). During the lithium-ion battery testing and assembly process, a lithium metal sheet was used as the negative electrode, a single-layer separator was used, and the prepared electrode sheet was used as the positive electrode. LB546-B was used as the electrolyte to assemble a CR2032 coin cell. The constant current charge-discharge test of the battery was performed on a Xinwei battery tester.
[0088] The test method for the rate discharge of lithium-ion batteries is as follows: the battery is charged and discharged in a constant temperature environment of 25°C. The discharge rates for each week are 0.5C, 1.0C, 1.5C, 2.0C, and 3.0C.
[0089] The test method for lithium-ion battery low-temperature operating capability (low-temperature capacity retention capability) is as follows: The battery is charged at a rate of 0.5C at 25℃ and discharged at a rate of 0.5C at a specified temperature under different ambient temperatures. The voltage range is the same as the voltage range of the above-mentioned rate discharge test. The charge and discharge cycle is performed for several weeks, and the specified temperature for each week is 25℃, 0℃, -10℃, and -20℃. The capacity retention rate at -20℃ / 25℃ is the ratio of the capacity discharged at a rate of -20℃ to the capacity discharged at a rate of 25℃. The closer the ratio is to 100%, the better the low-temperature discharge capability.
[0090] The test method for the cycle performance of lithium-ion batteries is as follows: The battery is charged and discharged in a constant temperature environment of 45℃, with the voltage range being the same as that of the above-mentioned rate discharge test. The charge and discharge cycles are performed for multiple cycles, with a charging rate of 0.5C and a discharging rate of 1.0C. The capacity retention rate after multiple cycles at 45℃ is the ratio of the discharge capacity of the last cycle to the discharge capacity of the first cycle. The higher the ratio, the better the cycle performance of the battery.
[0091] The test results are entered into Table 1 and Table 2.
[0092] Table 1
[0093]
[0094]
[0095] Table 2
[0096]
[0097] Depend on Figure 1 and Figure 2 It can be seen that the morphology of lithium cobalt oxide did not change significantly under C coating. As shown by the test data in Tables 1 and 2, the rate performance of the battery prepared with the cathode material of this embodiment is significantly improved, and the cycling performance and... Figure 5 The results show that lithium cobalt oxide coated with C material has better stability, and the initial impedance and impedance growth during cycling are effectively reduced, thereby improving cycling performance.
[0098] According to the test results of Examples 1 and 2, by first preparing cobalt carbonate crystal nuclei, the specific capacity and high-temperature cycling performance can be improved, with the high-temperature cycling performance improved by about 6%.
[0099] According to the test results of Examples 1, 3-5, Comparative Examples 2 and 4, reducing the content of carbon source A in carbon-coated lithium cobalt oxide and changing the type of doping element mainly affects the rate capability, low temperature performance and cycle performance.
[0100] According to the test results of Examples 1, 6-8 and Comparative Example 3, increasing the content of carbon source B in carbon-coated lithium cobalt oxide will increase cycle stability.
[0101] According to the test results of Examples 1, 9, and 10, changing the type of carbon source B does not achieve the effect of Example 1.
[0102] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing a lithium cobalt oxide cathode material, characterized in that, The following steps are included: To obtain cobalt carbonate with a particle size of 18-20 μm; Cobalt carbonate with a particle size of 18-20 μm and carbon source A were mixed, ball-milled, and calcined to obtain carbon-doped cobalt tetroxide powder. Carbon-doped cobalt tetroxide powder was mixed with lithium salt, ball-milled, calcined, and pulverized to obtain carbon-doped lithium cobalt oxide. Carbon source B, carbon-doped lithium cobalt oxide, and dispersant were mixed and then subjected to wet ball milling. The mixture after wet ball milling is calcined by passing a protective gas through it, and the calcined material is crushed and sieved to obtain carbon-coated lithium cobalt oxide. Based on the mass of the carbon-coated lithium cobalt oxide being 100%, the content of carbon source A in the carbon-coated lithium cobalt oxide is 0.2-0.5%, and the content of carbon source B in the carbon-coated lithium cobalt oxide is 1-3%. The carbon source A includes one or more of fructose, sucrose, tartaric acid, glucose, gluconic acid, and cellobiose; the carbon source B includes one or more of polyvinyl alcohol, polyacryl alcohol, phenolic resin, and polyvinyl alcohol.
2. The method for preparing lithium cobalt oxide cathode material according to claim 1, characterized in that, The preparation method of cobalt carbonate with a particle size of 18-20 μm is as follows: prepare cobalt sulfate solution and ammonium bicarbonate solution to synthesize cobalt carbonate with a particle size of 7-9 μm; prepare cobalt sulfate solution and ammonium bicarbonate solution, and use cobalt carbonate with a particle size of 7-9 μm as crystal nuclei to synthesize cobalt carbonate with a particle size of 18-20 μm.
3. The method for preparing lithium cobalt oxide cathode material according to claim 2, characterized in that, The concentration of the cobalt sulfate solution is 1.5-1.8 mol / L, and the concentration of the ammonium bicarbonate solution is 2.1-2.5 mol / L.
4. The method for preparing lithium cobalt oxide cathode material according to claim 2, characterized in that, In the preparation of cobalt carbonate with a particle size of 7-9 μm, the pH of the reaction solution was controlled at 7.2±0.2, the reaction temperature at 20-25℃, and the stirring speed at 580-600 r / min; when the particle size of cobalt carbonate was between 9-20 μm, the pH of the reaction solution was controlled at 7.2±0.2, the reaction temperature at 30-35℃, and the stirring speed at 480-500 r / min.
5. The method for preparing the lithium cobalt oxide cathode material according to claim 1, characterized in that, When mixing carbon-doped cobalt tetroxide powder with lithium salt, the ball milling speed is 400-420 r / min, the ball milling time is 6-7 h, the particle size of the ball milling beads is 11-12 mm, the total mass ratio of carbon-doped cobalt tetroxide powder and lithium salt to the mass ratio of ball milling beads is 1:15, and the mass ratio of carbon-doped cobalt tetroxide powder to lithium salt is 1:(1.06-1.1).
6. The method for preparing the lithium cobalt oxide cathode material according to claim 1, characterized in that, In the step of preparing cobalt tetroxide powder, the calcination temperature is 480-500℃, and the holding time is 9-10h; In the step of preparing carbon-doped lithium cobalt oxide, the calcination temperature is 880-900℃ and the holding time is 11-12h; In the step of preparing carbon-coated lithium cobalt oxide, the calcination temperature is 280-300℃, and the holding time is 4-6h.
7. A lithium cobalt oxide cathode material, characterized in that, It is prepared by the method for preparing lithium cobalt oxide cathode material according to any one of claims 1-6.
8. A positive electrode plate, characterized in that, Includes the lithium cobalt oxide cathode material as described in claim 7, or the lithium cobalt oxide cathode material prepared by the preparation method of the lithium cobalt oxide cathode material as described in any one of claims 1-6.
9. A battery, characterized in that, Includes the positive electrode sheet as described in claim 8.