Limited-range modified lithium-rich manganese-based positive electrode material as well as preparation method and application thereof
Through the confined modification preparation method, activated carbon and urea are used to construct nano-confined space, which solves the problems of microstructural heterogeneity and cycle stability of lithium-rich manganese-based positive electrode materials, achieves improvements in high specific capacity and long cycle performance, simplifies the preparation process and reduces costs.
Patent Information
- Application Number
- CN202510867981.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-26
- Publication Date
- 2025-10-10
AI Technical Summary
The existing technology for preparing lithium-rich manganese-based positive electrode materials has problems such as complex operation process and unclear performance improvement, especially in terms of microstructure and cycle stability, which are difficult to meet the needs of industrial applications.
A confined modification preparation method is adopted. By adding high specific surface area activated carbon and urea to the mixed solution, a nanoscale confined space is constructed, and a confined modified lithium-manganese-rich positive electrode material is formed by calcination. Combined with the functional modification effect of urea, the uniformity and structural stability of the material are achieved.
The specific capacity and cycle stability of the material have been significantly improved, with the initial discharge specific capacity ≥290mAh/g and the capacity retention rate >90% after 500 cycles, simplifying the preparation process and reducing costs.
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Figure CN120757157A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of lithium-ion batteries, and in particular to a confined modified lithium-rich manganese-based positive electrode material, a preparation method and applications thereof. Background Art
[0002] The cathode material is one of the key factors affecting the performance of lithium-ion batteries and is also the key to improving energy density. Compared with the currently commercialized cathode materials, lithium-rich manganese-based cathode materials have higher energy density (>250mAh g -1 ), a higher operating voltage (approximately 3.6V), and other advantages make it a very promising next-generation cathode material. Current synthesis methods for lithium-rich manganese-based cathode materials primarily include solid-phase synthesis, sol-gel synthesis, co-precipitation, and spray drying, with continued advancements towards process optimization and novel technologies.
[0003] Among them, the solid-phase method is simple, low-cost and easy to industrialize, but uneven material mixing can easily lead to a wide particle size distribution and increased structural defects, resulting in low initial Coulombic efficiency and limited cycle stability.
[0004] The sol-gel method achieves highly uniform element distribution through molecular-level mixing, improving the electrochemical consistency of the material. However, it consumes a lot of energy and is complex, leading to high mass production costs. The co-precipitation method utilizes precursors to precisely control composition and morphology, optimizing material properties. However, it is highly sensitive to pH, requires strict process control, and requires complex equipment.
[0005] The spray drying method forms uniform microspheres by rapidly drying atomized droplets. It is suitable for continuous production, but the spray parameters need to be carefully controlled to avoid component segregation.
[0006] Lithium-rich manganese-based materials synthesized by different methods differ in microstructure and other aspects, and their electrochemical properties will also be affected. In addition, the difficulty and complexity of the industrial operation of material production will also affect the actual production application. In order to break through the performance bottleneck, process optimization and modification strategies have become the focus. The existing technology uses the regulation of lithium-manganese stoichiometric ratio and the design of calcination temperature gradient (such as step-by-step sintering) to optimize the integrity of the crystal structure and reduce cation mixing. The introduction of elements such as Mg, Ti, and Al to occupy lattice sites can enhance structural stability and increase the ion diffusion rate, thereby inhibiting the cycle voltage decay. Carbon layer, oxide (such as Al2O3) or fast ion conductor (such as Li3PO4) coating is used to reduce electrolyte interface side reactions, but it is easy to introduce interface impedance or impurity phases. However, although the existing technology improves the cycle, it is difficult to fundamentally solve the problem of capacity decay. At the same time, industrial production operation is difficult and costly.
[0007] Therefore, the development of low-cost synthesis technology and new modification strategies remains the core research direction for promoting the commercial application of lithium-rich manganese-based materials. Summary of the Invention
[0008] The present invention provides a confined modified lithium-rich manganese-based positive electrode material, a preparation method and an application thereof, in order to solve the problems of the prior art in that the operation process is complicated and the performance of the obtained material is not significantly improved.
[0009] In order to achieve the above object, the technical solution of the present invention is: a method for preparing a confined modified lithium-rich manganese-based positive electrode material, comprising the following steps:
[0010] Step 1: According to the chemical formula Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 The soluble metal lithium salt, metal nickel salt, metal cobalt salt and metal manganese salt are dissolved in a solvent and stirred to obtain a mixed solution;
[0011] Step 2: Add activated carbon as a confinement material and urea as a modifying material to the mixed solution and stir evenly, evaporate the solvent while heating and stirring, and then dry to obtain a lithium-rich manganese-based cathode material precursor powder;
[0012] Step 3: calcining the precursor powder in a muffle furnace in an air atmosphere to obtain a modified lithium-rich manganese-based positive electrode material.
[0013] Furthermore, in step 1, the metal lithium salt is lithium acetate, lithium sulfate or lithium nitrate; the metal nickel salt is nickel acetate, nickel sulfate or nickel nitrate; the metal cobalt salt is cobalt acetate, cobalt sulfate or cobalt nitrate; the metal manganese salt is manganese acetate, manganese sulfate or manganese nitrate; and the solvent is deionized water or ethanol.
[0014] Furthermore, in step 1, the total concentration of metal ions in the mixed solution is 0.1-1 mol / L; the stirring speed during solution mixing is 300-600 rpm / min, the stirring time is 12-20 h, and the stirring temperature is 20-40°C.
[0015] Furthermore, in step 2, the activated carbon has a specific surface area of 1000-5000m 2 / g of activated carbon, the added amount is 5-10g / L; the added amount of urea is 0.015-0.1mol / L.
[0016] Furthermore, in step 2, the stirring speed during solution mixing is 300-600 rpm / min, the stirring temperature is 100-200° C.; the drying temperature is 110-150° C., and the drying time is 12-24 h.
[0017] Further, in the step three, the heating rate of the muffle furnace for calcining the precursor powder is 2-5℃ / min, the calcining temperature reaches 800-1100℃, and the calcining time is 0.1-2h, the calcining atmosphere is air, and the calcining is naturally cooled to room temperature.
[0018] Further, the lithium-rich manganese-based positive electrode material prepared by the preparation method.
[0019] Further, the lithium-rich manganese-based positive electrode material prepared by the preparation method.
[0020] Compared with the prior art, the advantages of the present application are:
[0021] 1. Compared with the current technical system, the present application firstly creatively introduces a three-dimensional limited modification strategy. The innovative core of the strategy is to cleverly use high specific surface area activated carbon to construct a nano-scale limited space. In this precisely constructed limited field, the grain growth of the lithium-rich manganese positive electrode material is effectively regulated, ensuring high uniformity of its size and completely suppressing the phenomenon of aggregation and growth, thereby fundamentally optimizing the microstructure of the material. At the same time, the present application creatively combines the functional modification effect of urea to realize efficient nitrogen reduction effect in the limited space. Thanks to this synergistic modification mechanism, the lithium-rich manganese positive electrode material prepared ultimately exhibits a significant increase in specific capacity and a significant enhancement in cycle stability. The synergistic effect of this limited structure regulation and in-situ nitrogen doping enables the material to exhibit excellent performance of specific capacity ≥ 290mAh / g and capacity retention rate > 90% after 500 cycles at a current density of 0.1C (1C = 200mA / g) in the voltage range of 2.0-4.8V.
[0022] 2. The preparation method is simple and low in cost: In the design of the preparation process of the present application, it is particularly valuable that the entire process flow achieving such superior performance is greatly simplified, and only three efficient steps are needed to complete, greatly improving the feasibility and efficiency of production. The lithium-rich manganese-based positive electrode material prepared has no impurity residues, so there is no need for steps such as separation and purification, which can reduce energy consumption, shorten the production process cycle, and facilitate practical application.
[0023] 3. Wide application range, the product of the present application has a wide application range in lithium ion batteries, and is particularly suitable for high-energy-density power battery systems. BRIEF DESCRIPTION OF DRAWINGS
[0024] Figure 1 X-ray diffraction curve (XRD) comparison chart of Comparative Example 1, Example 1, Example 2, Example 3, and Example 4;
[0025] Figure 2 Scanning electron microscope (SEM) chart of Comparative Example 1, Example 1, Example 2, Example 3, and Example 4;
[0026] Figure 3 for Example 2, and elemental mapping of the selected area SEM image of Example 2;
[0027] Figure 4 for Example 2, and elemental mapping of the selected area SEM image of Example 2;
[0028] Figure 5 for Example 2, and elemental mapping of the selected area SEM image of Example 2;
[0029] Figure 6 for Example 2, and elemental mapping of the selected area SEM image of Example 2;
[0030] Figure 7 for Example 2, and elemental mapping of the selected area SEM image of Example 2. DETAILED DESCRIPTION
[0031] The preparation method of the present application will be further illustrated by specific examples. It should be understood by those skilled in the art that the examples are only to help understand the present application and should not be regarded as specific limitations of the present application.
[0032] Example 1, the present application provides a preparation method of a confined modified lithium-rich manganese-based positive electrode material, comprising the following steps:
[0033] Step one, according to the chemical formula Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O2, lithium acetate, nickel acetate, cobalt acetate and manganese acetate are dissolved in deionized water and stirred, and the total concentration of metal ions in the mixed solution is controlled at 0.1 mol / L; the stirring speed is 300 rpm / min, the stirring time is 12 h, and the stirring temperature is 25℃, to obtain a mixed solution;
[0034] Step two, add activated carbon with a specific surface area of 2000 m 2 / g as a confined material to the mixed solution at an amount of 5 g / L, and add 0.015 mol / L of urea as a modification material, and stir while heating, with a stirring speed of 300 rpm / min and a stirring temperature of 120℃. After the solvent is evaporated, the recrystallized material is placed in a forced air drying machine at a temperature of 120℃ for 24 h, and the lithium-rich manganese-based positive electrode material precursor powder is obtained after drying;
[0035] Step 3: The precursor powder is calcined in a muffle furnace at a heating rate of 3°C / min. After reaching 1000°C, the calcination is continued for 0.5 h. The calcination process is carried out in an air atmosphere, with air continuously supplied to the muffle furnace by a blower. After cooling naturally to room temperature, the product is ground into powder to obtain a lithium-rich manganese-based cathode material.
[0036] In Example 2, the present invention provides a method for preparing a confined modified lithium-rich manganese-based positive electrode material, comprising the following steps:
[0037] Step 1: According to the chemical formula Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 Lithium acetate, nickel acetate, cobalt acetate and manganese acetate were dissolved in deionized water with stirring at a stoichiometric ratio of 1% to 2% O2, and the total concentration of metal ions in the mixed solution was controlled at 0.15 mol / L; the stirring speed was 300 rpm / min, the stirring time was 12 h, and the stirring temperature was 25°C to obtain a mixed solution;
[0038] Step 2: Add a specific surface area of 2000m 2 / g activated carbon was added as the confinement material in an amount of 6g / L, and 0.025mol / L urea was added as the modifying material. The mixture was heated and stirred at a speed of 300rpm / min and a stirring temperature of 120°C. After the solvent was evaporated to dryness, the resulting recrystallized material was placed in a forced air dryer at 120°C for 24 hours to obtain a lithium-rich manganese-based cathode material precursor powder.
[0039] Step 3: The precursor powder is calcined in a muffle furnace at a heating rate of 3°C / min. After reaching 1000°C, the calcination is continued for 0.5 h. The calcination process is carried out in an air atmosphere, with air continuously supplied to the muffle furnace by a blower. After cooling naturally to room temperature, the product is ground into powder to obtain a lithium-rich manganese-based cathode material.
[0040] Example 3, a method for preparing a confined modified lithium-rich manganese-based positive electrode material, comprising the following steps: the difference from Example 2 is that 0.035 mol / L of urea is added as a modifying material in step 1, the calcination temperature in step 3 is 1000°C, and the calcination time is 0.2h.
[0041] Example 4 is different from Example 3 in that 0.055 mol / L urea is added as a modifying material in step 1.
[0042] Comparative Example 1 provides a method for preparing a confined modified lithium-rich manganese-based positive electrode material. The preparation method is the same as Example 1 except that urea is not added in step 1.
[0043] The above-mentioned comparative example 1 and examples 1-4 were added to a ball mill jar with a mass ratio of 8:1 with the conductive agent SuperP, and wet-milled with ethanol. The ball milling speed was 300 rpm / min, the ball-to-material ratio was 100:1, and the ball milling time was 4 hours. The wet-milled sample was dried in a forced air drying oven at 80°C for 12 hours to obtain a composite material of lithium-rich manganese-based active material and conductive agent. The composite material was then slurried with a CMC binder, and after coating, drying, and cutting, it was used as a positive electrode. The positive electrode and the counter electrode lithium sheet were assembled into a lithium-ion button half-cell, and different test parameters were set to explore the electrochemical properties of the prepared positive electrode material.
[0044] like Figure 1 As shown in the X-ray diffraction curve, Example 1, Example 2, Example 3, and Example 4 are all typical lithium-rich manganese structures, without any new impurity phases being generated, and can well correspond to the α-NaFeO2 type layered structure. The diffraction peaks at 20-24° all correspond well to the superstructure of the C2 / m phase in the lithium-rich manganese material.
[0045] pass Figure 2 The SEM test results were further analyzed for morphology and elements. The particles of the material samples of Comparative Example 1 and Examples 1-4 were evenly distributed, with no significant change in size, all approximately 300-500 nm. There was no significant change in particle morphology between Examples 1-4 and Comparative Example 1.
[0046] like Figure 3 From the particle element distribution diagram of Example 2, it can be seen that the Mn, Ni, and Co elements are evenly distributed on the surface of the material of Example 2, and are consistent with the designed Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 The stoichiometric ratio of O2 is similar, and a small amount of N element is present, indicating that urea reacts with the precursor after calcination, so that a small amount of N element is doped into the lithium-rich manganese positive electrode material.
[0047] First charge and discharge curve from 0.1C (1C = 200mA / g) Figure 4 It can be seen that compared with the first discharge capacity of 275 mAh / g of comparative example 1, the first discharge capacity of Examples 1-4 at 0.1C is improved. Among them, the first discharge capacity of Example 2 is as high as 292 mAh / g, which is about 20 mAh / g higher than the first discharge capacity of comparative example 1, and its first coulombic efficiency is also improved to 82%. From the 500 long cycle graph at 1C ( Figure 5 ) It can be seen that the capacity retention rate of comparative example 1 is 66%, while the cycle performance of the embodiments is greatly improved, among which the capacity retention rate of embodiment 2 is 94%, and the capacity retention rate of embodiment 4 is 91%.
[0048] The data in Table 1 shows that, under the conditions of room temperature 29℃ and voltage range 2.0-4.8V, the modified examples 1-4 significantly improve the first discharge specific capacity of the positive electrode material, the first cycle coulombic efficiency is improved, and the long cycle performance is better. Figure 4 Figure 5
[0049] Table 1 Characteristic parameters of the electrochemical performance in the comparative examples and examples
[0050]
[0051]
[0052] Through XPS test ( Figure 6 ), the transition metal ions in the modified positive electrode material mainly exist in mixed valence state, and the ratio of Mn 4+ / Mn 3+ , Ni 3+ / Ni 2+ and Co 2+ / Co 3+ shows that example 2 mainly exists in Mn 3+ , Ni 2+ and Co 2+ valence state. Figure 7 The TEM and SEAD images of example 2 are shown, and it can be seen from the images that the particle size of example 2 is uniform, the test lattice fringe is found to be 0.468nm, which corresponds to the (003) crystal face of the lithium-rich manganese positive electrode material. The existence of (003) crystal face is further confirmed by the diffraction pattern of SEAD image, which shows that the crystal structure of the lithium-rich manganese positive electrode material after confinement modification does not change.
[0053] In the above examples, example 2 is the best embodiment.
[0054] In summary, the lithium-rich manganese-based positive electrode material prepared by the method of the present application has high first discharge specific capacity, high first charge-discharge efficiency and good capacity retention rate under long cycle.
[0055] The above examples only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as a limitation on the scope of the application. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of protection of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.
Claims
1. A method for preparing a confined modified lithium-rich manganese-based positive electrode material, characterized in that: The specific steps include: Step 1: According to the chemical formula Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 The soluble metal lithium salt, metal nickel salt, metal cobalt salt and metal manganese salt are dissolved in a solvent and stirred to obtain a mixed solution; Step 2: Add activated carbon as a confinement material and urea as a modifying material to the mixed solution and stir evenly, evaporate the solvent while heating and stirring, and then dry to obtain a lithium-rich manganese-based cathode material precursor powder; Step 3: calcining the precursor powder in a muffle furnace in an air atmosphere to obtain a modified lithium-rich manganese-based positive electrode material.
2. The method for preparing a confined modified lithium-rich manganese-based positive electrode material according to claim 1, characterized in that: In step 1, the metal lithium salt is lithium acetate, lithium sulfate or lithium nitrate; the metal nickel salt is nickel acetate, nickel sulfate or nickel nitrate; the metal cobalt salt is cobalt acetate, cobalt sulfate or cobalt nitrate; the metal manganese salt is manganese acetate, manganese sulfate or manganese nitrate; and the solvent is deionized water or ethanol.
3. The method for preparing a confined modified lithium-rich manganese-based positive electrode material according to claim 1, characterized in that: In the step 1, the total concentration of metal ions in the mixed solution is 0.1-1 mol / L; the stirring speed during solution mixing is 300-600 rpm / min, the stirring time is 12-20 h, and the stirring temperature is 20-40°C.
4. The method for preparing a chloride-modified lithium-rich manganese-based positive electrode material according to claim 1, characterized in that: In the step 2, the activated carbon has a specific surface area of 1000-5000 m 2 / g of activated carbon, the amount added is 5-10 g / L; the amount of urea added is 0.015-0.1 mol / L.
5. The method for preparing a confined modified lithium-rich manganese-based cathode material according to claim 1, characterized in that: In the step 2, the stirring speed during solution mixing is 300-600 rpm / min, the stirring temperature is 100-200° C.; the drying temperature is 110-150° C., and the drying time is 12-24 h.
6. The method for preparing a confined modified lithium-rich manganese-based cathode material according to claim 1, characterized in that: In the step 3, the precursor powder is calcined in a muffle furnace at a heating rate of 2-5°C / min, and the calcination temperature reaches 800-1100°C and then calcined for 0.1-2 h in an air atmosphere. After calcination, the precursor powder is naturally cooled to room temperature.
7. The lithium-rich manganese-based positive electrode material obtained by the preparation method according to claim 1.
8. Use of the lithium-rich manganese-based positive electrode material according to claim 7 in lithium-ion batteries.