Preparation method of single-crystal lithium-rich manganese-based positive electrode material and battery
By optimizing the sintering process parameters, a single-crystal lithium-rich manganese-based cathode material with uniform particle size was prepared, which solved the problems of voltage decay and poor cycle stability, and achieved high rate performance and long cycle life, making it suitable for industrial production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHENZHEN UNIV
- Filing Date
- 2026-03-05
- Publication Date
- 2026-06-05
AI Technical Summary
Existing technologies are difficult to effectively prepare high-performance single-crystal lithium-rich manganese-based cathode materials, resulting in problems such as voltage decay and poor cycle stability. Furthermore, existing process parameters are not suitable for single-crystal growth, making it difficult to guarantee consistency and performance.
By optimizing sintering process parameters, including high-temperature sintering, annealing, and cooling rate, uniform single-crystal particles were prepared. The specific steps included precursor preparation, pre-sintering, high-temperature sintering, and annealing. Temperature and time were optimized to promote single-crystal particle growth and structural stability.
High rate performance and cycle stability of single-crystal lithium-rich manganese-based cathode materials were achieved, significantly improving the electrochemical performance of the materials while reducing energy consumption and increasing production efficiency.
Smart Images
Figure CN122147494A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium-ion battery cathode material technology, specifically to an optimized preparation method for a single-crystal lithium-rich manganese-based cathode material, as well as the single-crystal lithium-rich manganese-based cathode material prepared by the method and a lithium-ion battery containing the cathode material. Background Technology
[0002] With the rapid development of electric vehicles and large-scale energy storage, higher demands are being placed on the energy density of lithium-ion batteries. Lithium-rich manganese-based cathode materials xLi₂MnO₃·(1-x)LiM 0.6 O2 (M = Ni, Co, Mn, etc.) is considered one of the most promising cathode materials for next-generation high-energy-density lithium-ion batteries due to its reversible specific capacity of up to 280 mAh / g and excellent energy density.
[0003] However, these materials face two major challenges in practical applications: voltage decay and poor cycling stability. Single-crystalization is an effective strategy to alleviate these problems. Single-crystal materials have advantages such as small specific surface area, high structural integrity, and high tap density, which can effectively suppress side reactions and particle cracking.
[0004] However, the preparation of single-crystal lithium-rich manganese-based materials faces severe challenges: First, lithium-rich materials have complex structures, and single-crystal growth requires high-temperature and long-term sintering, resulting in high energy consumption; second, the process window is narrow, and single crystals cannot be formed at too low a temperature, while excessively high temperatures can easily lead to lithium volatilization and the formation of impurity phases; third, the single-crystal particles are relatively large, resulting in long Li⁺ diffusion paths and a decrease in rate performance; fourth, existing technologies lack sufficient research on the synergistic optimization of parameters such as sintering temperature, holding time, annealing temperature, and cooling rate, making it difficult to guarantee product consistency and performance.
[0005] Currently, there are some studies on the modification of lithium-rich manganese-based cathode materials. For example, patent application CN109309215A discloses a modified lithium-rich manganese-based cathode material, which improves performance by doping with elements such as Zr and Si; patent application CN120895612A discloses a modified lithium-rich manganese-based cathode material, which uses borides and metal hydroxides for surface coating. However, these technologies mainly target polycrystalline secondary particles or materials with undefined crystal forms, and do not involve the growth control of single-crystal particles. Moreover, the coating layer only acts on the surface and cannot improve the bulk structure, resulting in limited suppression of voltage decay. At the same time, the sintering temperature and time ranges given in these patents are wide, without providing the optimal parameter combination for single-crystal growth, making it difficult to achieve the controllable preparation of single-crystal particles with uniform particle size. Summary of the Invention
[0006] In view of this, the present invention provides a single-crystal lithium-rich manganese-based cathode material Li 1.2 Mn 0.6 Ni0.2 The optimized preparation method of O2 achieves controllable preparation of single crystal particles by systematically optimizing sintering process parameters. This improves the structural stability of the material while obtaining excellent rate performance and cycle stability, especially solving the problem of poor high-rate performance of single crystal materials.
[0007] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for preparing a single-crystal lithium-rich manganese-based cathode material, comprising the following steps: (1) Preparation of precursor: Lithium source, nickel source and manganese source are dissolved in deionized water in stoichiometric ratio to obtain mixed salt solution; precipitant is dissolved in deionized water to obtain precipitant solution; mixed salt solution is added dropwise to precipitant solution and stirred to form coprecipitate; the obtained precipitate is evaporated to dryness to obtain precursor powder; (2) Pre-calcination treatment: The precursor powder obtained in step (1) is placed in a muffle furnace and heated to 400~600℃ in an air atmosphere for 2~5 hours to remove organic matter and water of crystallization; (3) High-temperature sintering: Take out the pre-fired material, grind it, and put it back into the muffle furnace. Heat it to 800~950℃ in air atmosphere and hold it for 10~30 hours to promote the growth of single crystal particles. (4) Annealing treatment: After high-temperature sintering, the temperature is reduced to 250-400℃ at a rate of 2-8℃ / min, and the temperature is held for 3-8 hours to perform annealing treatment to obtain single-crystal lithium-rich manganese-based cathode material.
[0008] Preferably, in step (1), the lithium source is lithium acetate, the nickel source is nickel acetate, the manganese source is manganese acetate, and the precipitant is oxalic acid.
[0009] Preferably, the temperature of the pre-firing treatment in step (2) is 500°C and the holding time is 3 hours.
[0010] Preferably, the high-temperature sintering temperature in step (3) is 900°C and the holding time is 12 hours.
[0011] Preferably, the annealing temperature in step (4) is 300°C and the holding time is 5 hours.
[0012] Preferably, the cooling rate in step (4) is 5°C / minute.
[0013] Preferably, the chemical formula of the single-crystal lithium-rich manganese-based cathode material is Li. 1.2 Mn 0.6 Ni 0.2 O2.
[0014] The present invention also provides a single-crystal lithium-rich manganese-based cathode material, which is prepared by any of the preparation methods described above.
[0015] Preferably, the material is in the form of single-crystal particles with a particle size of 0.8 to 1.2 micrometers.
[0016] Preferably, the material has a discharge specific capacity of ≥145 mAh / g at a 5C rate.
[0017] Secondly, the present invention also provides a lithium-ion battery comprising the above-mentioned single-crystal lithium-rich manganese-based cathode material.
[0018] Compared to existing technologies, it has the following beneficial effects: 1) Excellent rate performance: Li prepared under optimal process conditions (900℃-12h + 300℃ annealing + 5℃ / min cooling) 1.2 Mn 0.6 Ni 0.2 O2 single crystal materials maintain a discharge specific capacity of over 150 mAh / g at both 0.5C and 2C rates, and can still reach 145 mAh / g at a high 5C rate, which is significantly better than conventional single crystal materials.
[0019] 2) Excellent cycle stability: No significant capacity decay after 250 cycles at 2C rate, and it remains stable after 250 cycles at 0.5C rate, demonstrating excellent long cycle life.
[0020] 3) Significant structural advantages: Single crystal particles with a diameter close to 1 micrometer can be obtained under the 900℃-12h condition, which is larger than the particle size under the 800℃-12h condition; the larger particle size results in a smaller specific surface area, reducing side reactions with the electrolyte and which is beneficial to high-rate cycling stability.
[0021] 4) Improved process efficiency: Compared with the 800℃-24h process, the 900℃-12h process achieves comparable or better performance while halving the heat preservation time and significantly reducing energy consumption, thus having higher industrial production value. Attached Figure Description
[0022] Figure 1 This invention relates to a one-step oxalic acid coprecipitation method for preparing Li 1.2 Mn 0.6 Ni 0.2 O2 process flow diagram.
[0023] Figure 2 This is a comparison chart of the rate performance of samples sintered at different temperatures, proving that the rate performance is optimal at 900℃.
[0024] Figure 3 These are SEM images of samples sintered at different temperatures, demonstrating that the higher the temperature, the larger the particle size.
[0025] Figure 4The graph shows the long-cycle performance of the 900℃-12h sample at different magnifications, proving that there is no attenuation after 250 cycles at 0.5C and 2C.
[0026] Figure 5 The graph shows a comparison of the magnification performance of samples annealed at different temperatures, proving that annealing at 300℃ is far superior to annealing at 500℃.
[0027] Figure 6 This is a comparison chart of the scaling performance of samples with different cooling rates, proving that 5℃ / min has better overall performance. Detailed Implementation
[0028] The present 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 only for explaining the present invention and are not intended to limit the present invention.
[0029] Before providing a further detailed description of the present invention, the nouns and terms used in the embodiments of the present invention will be explained, and the nouns and terms used in the embodiments of the present invention shall be interpreted as follows.
[0030] Please see Figure 1 This invention provides a method for preparing a single-crystal lithium-rich manganese-based cathode material, comprising the following steps: Precursor preparation: Lithium source, nickel source and manganese source are dissolved, mixed with precipitant, and the precursor precipitate is obtained by co-precipitation reaction; Pre-calcination treatment: The precursor is heated to 400~600℃ in air atmosphere and held for 2~5 hours; High-temperature sintering: The pre-fired material is heated to 800~950℃ in air and held for 10~30 hours; Annealing treatment: After high-temperature sintering, the temperature is lowered to 250~400℃ and held for 3~8 hours to obtain single-crystal lithium-rich manganese-based cathode material.
[0031] Through systematic process optimization experiments, this invention has determined the following key process parameter windows and their preferred values, as shown in Table 1.
[0032] Table 1 Example 1 (1) Precursor preparation: Lithium acetate, nickel acetate, and manganese acetate were dissolved in deionized water at a molar ratio of Li:Ni:Mn = 1.2:0.2:0.6 to prepare a mixed salt solution. Oxalic acid was dissolved in deionized water to prepare a precipitant solution. The mixed salt solution was slowly added dropwise to the oxalic acid solution, and the mixture was stirred to form a coprecipitate. The precipitate was evaporated to dryness to obtain the precursor powder.
[0033] (2) Pre-calcination treatment: The precursor powder is placed in a muffle furnace and heated to 500°C at 5°C / min under air atmosphere. It is then held for 3 hours to remove organic matter and water of crystallization.
[0034] (3) High-temperature sintering: Take out the pre-burned powder, grind it, and put it back into the muffle furnace. Under air atmosphere, heat it to 900℃ at 5℃ / min and hold it for 12 hours to carry out high-temperature sintering to promote the growth of single crystal particles.
[0035] (4) Annealing treatment: After high-temperature sintering, the temperature was lowered to 300℃ at a rate of 5℃ / min and held for 5 hours for annealing treatment to eliminate internal stress and optimize the crystal structure. Then, it was naturally cooled to room temperature, removed and ground to obtain the target product Li. 1.2 Mn 0.6 Ni 0.2 O2 single crystal material.
[0036] Performance testing: 0.5C rate: Discharge specific capacity above 150 mAh / g; 2C rate: Discharge specific capacity above 150 mAh / g, with no capacity decay after 250 cycles; 5C rate: Discharge specific capacity is approximately 145 mAh / g; SEM characterization: The single crystal particles have a diameter of approximately 1 micrometer.
[0037] Example 2 (Temperature Comparison -800℃) The sintering temperature was changed to 800℃ and held for 12 hours, with the other conditions the same as in Example 1.
[0038] Example 3 (Temperature Comparison -850℃) The sintering temperature was changed to 850℃ and held for 12 hours. The other conditions were the same as in Example 1.
[0039] Example 4 (Temperature Comparison -950℃) The sintering temperature was changed to 950℃ and held for 12 hours, with the other conditions the same as in Example 1.
[0040] Example 5 (Insulation Time Comparison - 24h) The sintering temperature was 900℃, the holding time was changed to 24 hours, and the other conditions were the same as in Example 1.
[0041] Example 6 (Annealing temperature comparison -500℃) The annealing temperature was changed to 500℃, and the other conditions were the same as in Example 1.
[0042] Example 7 (Comparison of cooling rates -2℃ / min) The cooling rate was changed to 2℃ / min, and the other conditions were the same as in Example 1.
[0043] Test Result Analysis Figure 2 The rate performance of samples sintered at different temperatures was shown. The 900℃ sample exhibited the highest discharge specific capacity at all rates, confirming that 900℃ is the optimal sintering temperature. Figure 3 SEM images show that the single crystal size gradually increases with increasing sintering temperature, reaching its maximum at 950℃, but the rate performance decreases, which may be related to lithium volatilization.
[0044] Figure 4 The long-cycle performance of the sample at 900℃-12h was demonstrated. After 250 cycles at 0.5C and 2C, the capacity remained stable with no significant decay, proving its excellent cycling stability.
[0045] Figure 5 The rate performance of samples annealed at 300℃ and 500℃ was compared. The samples annealed at 300℃ were significantly better than those annealed at 500℃ at all rates, indicating that low-temperature annealing is more conducive to maintaining the stability of the material structure.
[0046] Figure 6 The rate performance of samples with cooling rates of 2℃ / min and 5℃ / min was compared. The 5℃ / min rate showed a significant advantage at low rates. At a 5℃ rate, the rate was slightly lower than that of 2℃ / min, but the difference was very small. The overall performance was better, so the 5℃ / min rate was preferred.
[0047] A comparison of Example 5 (900℃-24h) and Example 1 (900℃-12h) revealed that extending the heat preservation time did not significantly improve the rate performance. However, the rate performance of 900℃-12h and 800℃-24h was similar, but the particle size of 900℃-12h was larger, and the heat preservation time was halved, resulting in lower energy consumption, which demonstrates the process advantages of the present invention.
[0048] In summary, this invention has successfully achieved the controllable preparation of single-crystal lithium-rich manganese-based cathode materials by systematically optimizing sintering temperature, holding time, annealing temperature, and cooling rate. The resulting materials have excellent rate performance and cycle stability, and the process is simple, energy-efficient, and suitable for industrial production.
[0049] 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 single-crystal lithium-rich manganese-based cathode material, characterized in that, Includes the following steps: Precursor preparation: Lithium source, nickel source and manganese source are dissolved, mixed with precipitant, and the precursor precipitate is obtained by co-precipitation reaction; Pre-calcination treatment: The precursor is heated to 400~600℃ in air atmosphere and held for 2~5 hours; High-temperature sintering: The pre-fired material is heated to 800~950℃ in air and held for 10~30 hours; Annealing treatment: After high-temperature sintering, the temperature is lowered to 250~400℃ and held for 3~8 hours to obtain single-crystal lithium-rich manganese-based cathode material.
2. The preparation method according to claim 1, characterized in that, The high-temperature sintering temperature is 900℃, and the holding time is 12 hours.
3. The preparation method according to claim 1, characterized in that, The annealing process is performed at a temperature of 300°C for 5 hours.
4. The preparation method according to claim 1 or 3, characterized in that, The cooling rate is 5°C / minute.
5. The preparation method according to claim 1, characterized in that, The lithium source is lithium acetate, the nickel source is nickel acetate, the manganese source is manganese acetate, and the precipitant is oxalic acid; the pre-calcination treatment temperature is 500℃, and the holding time is 3 hours.
6. The preparation method according to claim 1, characterized in that, The chemical formula of the single-crystal lithium-rich manganese-based cathode material is Li. 1.2 Mn 0.6 Ni 0.2 O2.
7. A single-crystal lithium-rich manganese-based cathode material, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 6.
8. The single-crystal lithium-rich manganese-based cathode material according to claim 7, characterized in that, The material is in the form of single-crystal particles with a particle size of 0.8~1.2 micrometers.
9. The single-crystal lithium-rich manganese-based cathode material according to claim 7 or 8, characterized in that, The material has a discharge specific capacity of ≥145 mAh / g at a 5C rate.
10. A lithium-ion battery, characterized in that, It includes the single-crystal lithium-rich manganese-based cathode material as described in any one of claims 7 to 9.