A high-voltage lithium cobalt oxide composite material and a preparation method thereof
By forming a sodium zirconate coating on the surface of lithium cobalt oxide material, the problem of structural instability under high voltage is solved, the stability and performance of the material are improved, and the production cost is reduced.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HEFEI RONGJIE ENERGY MATERIALS CO LTD
- Filing Date
- 2023-06-26
- Publication Date
- 2026-06-05
AI Technical Summary
The structure of lithium cobalt oxide materials is prone to change under high voltage, which affects cycle performance. Furthermore, existing technologies require the introduction of oxygen to improve reaction efficiency, which increases production costs.
A sodium zirconate coating layer is formed on the surface of cobalt tetroxide using zirconium dioxide and sodium carbonate. Through a high-temperature alkaline fusion reaction, combined with lithium carbonate sintering, a high-voltage lithium cobalt oxide material coated with sodium zirconate is formed, avoiding the introduction of additional oxygen.
Stabilize the lithium cobalt oxide crystal structure, improve the material's cycle performance and rate performance, and reduce production costs.
Smart Images
Figure CN116812985B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to a high-voltage lithium cobalt oxide composite material and its preparation method. Background Technology
[0002] Lithium cobalt oxide is currently the main cathode material in commercially available lithium-ion batteries. It is widely used in digital 3C consumer electronics, e-cigarettes, electronic models (airplane models, car models, etc.), wireless electric toys, and other high-power electronic devices.
[0003] As the market develops, the operating voltage of lithium cobalt oxide materials is further increasing. Excessively high voltage can cause changes in the structure of lithium cobalt oxide materials, thus affecting their cycle performance. Furthermore, the preparation of lithium cobalt oxide requires oxygen for the reaction; in high-voltage lithium cobalt oxide preparation, current technologies typically introduce a certain amount of oxygen to ensure the reaction proceeds fully, which indirectly increases production costs. Summary of the Invention
[0004] This invention uses cobalt tetroxide as the matrix and zirconium dioxide and sodium carbonate as coating raw materials, which are mixed evenly and then calcined at high temperature. Zirconium dioxide and sodium carbonate undergo an alkaline fusion reaction at high temperature, forming a sodium zirconate coating layer on the surface of cobalt tetroxide. The coated cobalt tetroxide is then mixed evenly with an appropriate amount of lithium carbonate and sintered in air. After pulverization, a high-voltage lithium cobalt oxide composite material is obtained.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0006] A method for preparing a high-voltage lithium cobalt oxide composite material includes the following steps:
[0007] (1) Preparation of raw materials: Add an appropriate amount of cobalt tetroxide to a high-speed mixer, then add industrial-grade sodium carbonate and 0.16%-0.58% nano-zirconium dioxide at a mass ratio of 0.1%-0.5%, and mix at a stirring speed of 400-600 rpm for 20-30 minutes. Note: Based on the stoichiometric relationship between zirconium dioxide and sodium carbonate in the production of sodium zirconate, the mass of zirconium dioxide is 1.16 times that of sodium carbonate.
[0008] (2) Sintering: The mixed raw materials obtained in step 1) are loaded into a crucible, the muffle furnace is heated to 800-900℃, and sintered at this temperature for 8-12 hours. Then, the mixture is naturally cooled to room temperature to obtain material B.
[0009] (3) Crushing: The material B obtained in step 2) is crushed and sieved using an air jet mill. The air jet mill has a classification frequency of 10-20Hz, a feeding frequency of 15-30Hz, and a grinding pressure of 160-180Kpa to obtain sodium zirconate-cobalt tetroxide powder C;
[0010] (4) Mixing: Take the powder C obtained in step 3) and add it to a high-speed mixer. Add battery-grade lithium carbonate at a lithium-cobalt molar ratio of 1.02-1.08. Set the stirring speed to 400-600 rpm and mix for 20-30 minutes to obtain mixture D.
[0011] (5) Calcination: The mixture D obtained in step 4) is loaded into a crucible, the muffle furnace is heated to 850-950℃, and air is injected at a rate of 40-70L / min. The mixture is kept at this temperature for 10-14h and then cooled to room temperature to obtain material E.
[0012] (6) Crushing: The material E obtained in step 5) is crushed and sieved using an air jet mill. The air jet mill has a classification frequency of 10-20Hz, a feeding frequency of 15-30Hz, a grinding pressure of 160-180Kpa, and a sieve mesh of 325 mesh, thus obtaining high-voltage lithium cobalt oxide.
[0013] Compared with existing technologies, the beneficial effects of this invention are reflected in:
[0014] (1) This invention utilizes the alkaline fusion reaction of zirconium dioxide and sodium carbonate to form a sodium zirconate coating layer on the surface of cobalt tetroxide. By utilizing the property of sodium zirconate to absorb carbon dioxide, the carbon dioxide generated during the high-temperature reaction of cobalt tetroxide and lithium carbonate, as well as the high-temperature decomposition of lithium carbonate itself, is reduced, indirectly increasing the contact between oxygen and materials during the reaction, and ensuring normal production without the need for additional oxygen;
[0015] (2) In the sodium zirconate coating of this invention, when cobalt tetroxide reacts with lithium carbonate, zirconium and sodium ions are incorporated into the lithium cobalt oxide crystal structure. Zirconium ion doping stabilizes the lithium cobalt oxide crystal structure, ensuring that the crystal structure remains unchanged under high voltage conditions, thereby improving the material's cycle performance. Sodium and lithium have similar chemical properties, but the sodium ion radius is larger than that of lithium ions, which can broaden the lithium ion migration channels within the material, thus improving the material's rate performance.
[0016] (3) In the process of preparing high-voltage lithium cobalt oxide, the present invention does not require additional oxygen, which reduces the production cost of the material. Attached Figure Description
[0017] Figure 1 This is a cycle curve diagram of the battery made from the materials obtained in Example 1 and Comparative Example 1 of the present invention. Detailed Implementation
[0018] The present invention will be further described below with reference to embodiments, so that those skilled in the art can better understand and implement the present invention, but the embodiments are not intended to limit the present invention.
[0019] In addition, unless otherwise specified, the preparation processes in the following embodiments are all conventional methods in the prior art, and therefore will not be described in detail; the raw materials used in the following embodiments are all commercially available products.
[0020] Example 1
[0021] (1) Prepare the mixed raw materials: Take 100 kg of cobalt tetroxide and add it to the high-speed mixer, then add industrial grade sodium carbonate and 0.464% nano zirconium dioxide at a mass ratio of 0.4%, and mix at 500 rpm for 25 min.
[0022] (2) Sintering: The mixed raw materials obtained in step 1) are loaded into a crucible and heated to 850°C in a muffle furnace at a heating rate of 3°C / min. After holding at the temperature for 10 hours, the mixture is cooled to room temperature to obtain material B.
[0023] (3) Crushing: The material B obtained in step 2) is crushed and sieved using an air jet mill. The air jet mill has a classification frequency of 15Hz, a feeding frequency of 20Hz, and a grinding pressure of 170Kpa to obtain sodium zirconate-cobalt tetroxide powder C;
[0024] (4) Mixing: Take 50 kg of powder C obtained in step 3) and add it to a high-speed mixer. Add battery-grade lithium carbonate at a lithium-cobalt molar ratio of 1.065. Set the stirring speed to 500 rpm and stir for 25 min to obtain mixture D.
[0025] (5) Calcination: The mixture D obtained in step 4) is placed in a crucible in an oven and heated to 900°C in a muffle furnace at a heating rate of 3°C / min, while air is injected at a rate of 60L / min. The mixture is kept at this temperature for 12 hours and then cooled naturally to room temperature to obtain material E.
[0026] (6) Crushing: The material E obtained in step 5) is crushed and sieved using an air jet mill. The air jet mill has a classification frequency of 15Hz, a feeding frequency of 20Hz, a grinding pressure of 170Kpa, and a sieve mesh of 325 mesh. This yields high-voltage lithium cobalt oxide.
[0027] Example 2
[0028] Compared with Example 1, the difference in Example 2 is that the amount of industrial-grade sodium carbonate added is 0.1% of cobalt tetroxide, and the amount of nano-zirconia added is 0.16% of cobalt tetroxide. All other processes are the same as in Example 1.
[0029] Example 3
[0030] Compared with Example 1, the difference in Example 3 is that the amount of industrial-grade sodium carbonate added is 0.2% of cobalt tetroxide, and the amount of nano-zirconia added is 0.232% of cobalt tetroxide. All other processes are the same as in Example 1.
[0031] Example 4
[0032] Compared with Example 3, the difference in Example 4 is that the sintering temperature in step (2) is 800°C, while the other processes are the same as in Example 3.
[0033] Example 5
[0034] Compared with Example 3, the difference in Example 5 is that the sintering temperature in step (2) is 900°C, while the other processes are the same as in Example 3.
[0035] Comparative Example 1
[0036] (1) Prepare mixed raw materials: Take 100 kg of cobalt tetroxide and add it to the high-speed mixer. Add lithium carbonate at a lithium-cobalt ratio of 1.065 and mix at 500 rpm for 25 min.
[0037] (2) Sintering: The mixture D obtained in step 1) is loaded into a crucible, heated to 900°C in a muffle furnace at a heating rate of 3°C / min, while air is injected at a rate of 60L / min, and sintered at the temperature for 12 hours. The mixture is then cooled to room temperature to obtain material E.
[0038] (3) Crushing: The material D obtained in step 2) is crushed and sieved using an air jet mill. The air jet mill has a classification frequency of 15Hz, a feeding frequency of 20Hz, a grinding pressure of 170Kpa, and a sieve mesh of 325 mesh to obtain lithium cobalt oxide.
[0039] Comparative Example 2
[0040] (1) Preparation of mixed raw materials: Take 100 kg of cobalt tetroxide and add it to the high-speed mixer. Add lithium carbonate at a lithium-cobalt ratio of 1.065, and then add industrial-grade sodium carbonate and 0.232% nano-zirconium dioxide at a mass ratio of 0.2%. Mix at 500 rpm for 25 min.
[0041] (2) Sintering: The mixture D obtained in step 1) is loaded into a crucible, heated to 900°C in a muffle furnace at a heating rate of 3°C / min, while air is injected at a rate of 60L / min, and sintered at the temperature for 12 hours. The mixture is then cooled to room temperature to obtain material E.
[0042] (3) Crushing: The material D obtained in step 2) is crushed and sieved using an air jet mill. The air jet mill has a classification frequency of 15Hz, a feeding frequency of 20Hz, a grinding pressure of 170Kpa, and a sieve mesh of 325 mesh to obtain lithium cobalt oxide.
[0043] Comparative Example 3
[0044] (1) Prepare the mixed raw materials: Take 100 kg of cobalt tetroxide and add it to the high-speed mixer. Add lithium carbonate at a lithium-cobalt ratio of 1.065 and then add industrial-grade sodium carbonate at a mass ratio of 0.2%. Mix at 500 rpm for 25 min.
[0045] (2) Sintering: The mixture D obtained in step 1) is loaded into a crucible, heated to 900°C in a muffle furnace at a heating rate of 3°C / min, while air is introduced at a rate of 60L / min, and sintered at this temperature for 12 hours. The mixture is then allowed to cool naturally to room temperature to obtain material E.
[0046] (3) Crushing: The material D obtained in step 2) is crushed and sieved using an air jet mill. The air jet mill has a classification frequency of 15Hz, a feeding frequency of 20Hz, a grinding pressure of 170Kpa, and a sieve mesh of 325 mesh to obtain lithium cobalt oxide.
[0047] Comparative Example 4
[0048] (1) Preparation of mixed raw materials: Take 100 kg of cobalt tetroxide and add it to the high-speed mixer. Add lithium carbonate at a lithium-cobalt ratio of 1.065, and then add 0.232% nano zirconium dioxide by mass ratio. Mix at 500 rpm for 25 min.
[0049] (2) Sintering: The mixture D obtained in step 1) is loaded into a crucible, heated to 900°C in a muffle furnace at a heating rate of 3°C / min, while air is injected at a rate of 60L / min, and sintered at the temperature for 12 hours. The mixture is then cooled to room temperature to obtain material E.
[0050] (3) Crushing: The material D obtained in step 2) is crushed and sieved using an air jet mill. The air jet mill has a classification frequency of 15Hz, a feeding frequency of 20Hz, a grinding pressure of 170Kpa, and a sieve mesh of 325 mesh to obtain lithium cobalt oxide.
[0051] Comparative Example 5
[0052] (1) Prepare mixed raw materials: Take 100 kg of cobalt tetroxide and add it to the high-speed mixer. Add lithium carbonate at a lithium-cobalt ratio of 1.065 and mix at 500 rpm for 25 min.
[0053] (2) Sintering: The mixture D obtained in step 1) is loaded into a crucible, heated to 900°C in a muffle furnace at a heating rate of 3°C / min, and air is injected at a rate of 40L / min while oxygen is injected at a rate of 20L / min. The mixture is sintered at this temperature for 12 hours and then cooled to room temperature to obtain material E.
[0054] (3) Crushing: The material D obtained in step 2) is crushed and sieved using an air jet mill. The air jet mill has a classification frequency of 15Hz, a feeding frequency of 20Hz, a grinding pressure of 170Kpa, and a sieve mesh of 325 mesh to obtain lithium cobalt oxide.
[0055] Lithium cobalt oxide samples prepared in each embodiment and comparative example were used as the positive electrode active material. A positive electrode slurry was prepared by mixing the positive electrode active material, conductive agent (SP), and binder (PCDF) in a mass ratio of 95:5:5. This slurry was then coated onto the positive electrode current collector to form the positive electrode. A lithium sheet was used as the negative electrode. A conventional capacity-type electrolyte was selected, and the batteries were assembled into coin cells. The battery performance was tested using a battery performance tester at -20°C in a test chamber. The charge / discharge cutoff voltage was 3.0–4.55V, and the charge / discharge rates were 0.2C, 0.5C, and 1C. The test results are shown in Table 1 and [Table data missing]. Figure 1 :
[0056] Table 1. Performance test results of batteries made from materials prepared in the embodiments and comparative examples of the present invention.
[0057]
[0058] Combined with Table 1 Figure 1 Test results show that the lithium cobalt oxide prepared in the example exhibits significantly better discharge efficiency, capacity retention, and cycle performance than the control group without oxygen. This is because in the example, zirconium dioxide and sodium carbonate undergo alkali fusion on the surface of cobalt tetroxide to form a sodium zirconate coating. This allows the cobalt tetroxide to absorb the carbon dioxide produced during the reaction with lithium carbonate, indirectly improving the contact between oxygen and the material. Simultaneously, zirconium and sodium ions are incorporated during the growth of the lithium cobalt oxide crystal. Zirconium ion doping stabilizes the lithium cobalt oxide crystal structure, ensuring that the crystal structure remains unchanged under high voltage conditions, thus improving the material's cycle performance. Sodium has similar chemical properties to lithium, but its ion radius is larger than that of lithium ions, which can broaden the lithium ion migration channels within the material, thereby improving the material's rate performance.
[0059] It should be noted that in other embodiments, the objective of this invention can be achieved when the experimental process meets the following conditions:
[0060] The sintering time in step (2) is preferably 8-12h, specifically 8h, 9h or 12h.
[0061] For the lithium cobalt molar ratio of sodium zirconate-coated cobalt tetroxide powder C to lithium carbonate in step (4), the ratio is preferably 1.02-1.08, specifically 1.02, 1.04 or 1.08.
[0062] The preferred calcination temperature in step (5) is 850-950℃, specifically 850℃, 920℃ or 950℃; the preferred calcination time is 10-14h, specifically 10h, 13h or 14h.
[0063] Those skilled in the art can make appropriate selections of the above process parameters according to actual needs, and all of them can achieve the purpose of this invention.
[0064] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing a high-voltage lithium cobalt oxide composite material, characterized in that: Includes the following steps: Cobalt tetroxide, sodium carbonate, and nano-zirconium dioxide are mixed evenly to obtain a mixed raw material; the mixed raw material is sintered and pulverized to obtain cobalt tetroxide powder coated with sodium zirconate; Sodium zirconate-coated cobalt tetroxide powder and lithium carbonate are mixed evenly and then calcined. Air is introduced during calcination. After calcination, the resulting material is crushed to obtain a high-voltage lithium cobalt oxide composite material. The sodium carbonate is 0.1%-0.5% of cobalt tetroxide by mass; The nano-zirconia is 0.16%-0.58% of cobalt tetroxide by mass.
2. The method for preparing the high-voltage lithium cobalt oxide composite material according to claim 1, characterized in that: The sintering temperature is 800-900℃, and the sintering time is 8-12h.
3. The method for preparing the high-voltage lithium cobalt oxide composite material according to claim 1 or 2, characterized in that: The molar ratio of lithium to cobalt in the sodium zirconate-coated cobalt tetroxide powder and lithium carbonate is 1.02-1.
08.
4. The method for preparing the high-voltage lithium cobalt oxide composite material according to claim 3, characterized in that: The calcination temperature is 850-950℃, and the calcination time is 10-14h.
5. The method for preparing the high-voltage lithium cobalt oxide composite material according to claim 4, characterized in that: The air flow rate is 40-70 L / min.
6. A high-voltage lithium cobalt oxide composite material, characterized in that: It is prepared by the preparation method as described in any one of claims 1 to 5.