Microcube-shaped potassium ion battery positive electrode material and preparation method thereof
By preparing the microcube-shaped potassium ion battery positive electrode material, the problems of unstable and poor circulation performance of the potassium ion battery positive electrode material are solved, high-rate performance and long-cycle stability are achieved, and the cubes are assembled through hydrothermal reaction and calcination to form porous nanoparticles, which improves the electrochemical performance of the material.
Patent Information
- Application Number
- CN202510710900.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-29
- Publication Date
- 2025-08-26
AI Technical Summary
The existing potassium ion battery positive electrode material has unstable structure, poor circulation performance, and the ion transfer rate limits the development of high-rate performance.
The preparation method of the positive electrode material of a microcube-shaped potassium ion battery is adopted. Through hydrothermal reaction and calcination, a secondary microcube assembled with nanoparticles with porous structure is formed. CTAB is used as a cationic surfactant to provide specific spatial structure limitations, and a regular sheet-like self-assembly form a cube structure.
The specific surface area and K+ diffusion path of the material are improved, the electrochemical polarization and interface resistance are reduced, and the rapid K+ transfer and high rate performance are achieved, while alleviating the structural stability of the material during long cycles is maintained, and high capacity retention is maintained.
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Figure CN120535023A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of preparation of battery positive electrode materials, and particularly relates to a microcubic potassium ion battery positive electrode material and a preparation method thereof. Background Art
[0002] In recent years, lithium-ion batteries have received widespread attention in energy storage devices and have been widely used in various fields. However, the low natural abundance and uneven distribution of lithium make lithium-ion batteries more expensive. Therefore, there is an urgent need to develop a new type of battery that can replace lithium-ion batteries, such as sodium-ion batteries, potassium-ion batteries, magnesium-ion batteries, and calcium-ion batteries.
[0003] Potassium-ion battery cathode materials primarily include Prussian blue analogs, layered metal oxides, polyanionic compounds, and organic cathode materials. Layered metal oxides have attracted significant attention due to their ease of synthesis, compact layered structure, high theoretical capacity and volumetric density, low preparation cost, and environmental friendliness. Among various potassium-ion battery cathode materials, layered metal oxides have attracted significant attention due to their low molar mass and large interlayer spacing, which provide two-dimensional alkali metal ion diffusion channels. Layered cobalt-based oxides contribute to capacity changes through the intercalation and deintercalation of alkali metal ions between the layers during charge and discharge. However, due to the large ionic radius of potassium ions and the strong electrostatic repulsion between ions, stress accumulates during intercalation and deintercalation, leading to structural instability. Furthermore, current ion transport rates limit the development of high-rate materials, and the complex preparation process complicates the process. Existing potassium-ion cathode materials still suffer from low discharge capacity, instability, and poor cycling performance. Therefore, to address these shortcomings, a potassium-ion battery cathode material with long-term cycling stability and high-rate performance is needed. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to provide a microcubic potassium ion battery positive electrode material and a preparation method thereof, so as to solve the technical problems of instability and poor cycle performance of the potassium ion battery positive electrode material.
[0005] To achieve the above object, the technical solution adopted by the present invention is: to provide a method for preparing a microcubic potassium ion battery positive electrode material, comprising the following steps:
[0006] S1. Dissolve a cobalt salt, a manganese salt, and a surfactant in water at a molar ratio of 7-8:2-3:0.5-3, then adjust the pH value of the mixture to 8.5-9.5, and then place the mixture at 180-220° C. for a hydrothermal reaction for 12-18 hours. After cooling to room temperature, wash and dry to obtain a carbonate precursor;
[0007] S2. The carbonate precursor is placed at 450-550 ° C for the first calcination for 3-5 hours, and then dissolved in water with a sodium source at a molar ratio of 0.8-1.2:0.7-0.75, and dried at 70-100 ° C for 10-14 hours. Finally, the reactant is placed at 800-900 ° C for a second calcination for 12-15 hours. At this time, the carbonate decomposes into oxides and carbon dioxide. The material is originally a cube self-assembled by the sheets, but due to gas escape and material decomposition, it is transformed into a cube assembled by tiny sheets.
[0008] On the basis of the above technical solution, the present invention can also be improved as follows:
[0009] Furthermore, the cobalt salt is cobalt acetate or cobalt sulfate, the manganese salt is manganese acetate or manganese sulfate, and the surfactant is a cationic surfactant.
[0010] Furthermore, the surfactant is CTAB or CTAC. During the hydrothermal process, CTAB, as a cationic surfactant, provides specific spatial structural constraints for the reaction product, inducing the formation of regular flakes, which then self-assemble into a cubic structure.
[0011] Furthermore, the reagent used to adjust the pH value in S1 is urea. If an alkali solution containing sodium is used to adjust the pH value of the mixed solution, excess sodium source will be attached to the material, affecting the subsequent quantitative addition of the sodium source.
[0012] Furthermore, the cleaning liquid used for cleaning is deionized water and / or anhydrous ethanol.
[0013] Furthermore, the drying temperature in S1 and S2 is 70-100° C., and the drying time is 10-14 h.
[0014] Furthermore, the sodium source is sodium hydroxide or sodium carbonate.
[0015] Furthermore, the temperature of the primary calcination is 500° C., and the time of the primary calcination is 4 h; the temperature of the secondary calcination is 850° C., and the time of the primary calcination is 12 h.
[0016] The invention also discloses a microcubic potassium ion battery positive electrode material prepared by the preparation method.
[0017] On the basis of the above technical solution, the present invention can also be improved as follows:
[0018] Furthermore, the molecular formula of the microcubic potassium ion battery cathode material is Na 0.7 Co 0.75 Mn 0.25 O2.
[0019] The beneficial effects of the present invention are as follows: the potassium ion battery positive electrode material prepared by the present invention has a large specific surface area due to the hierarchical secondary microcube structure, which can increase the contact with the electrolyte through the layered porous structure, thereby increasing K + diffusion path, while reducing K + The diffusion distance is shortened, the electrochemical polarization is reduced, and the interface resistance is lowered, so that fast K + Transfer, get excellent rate performance. At the same time, this secondary microcube structure assembled by nanoparticles can effectively relieve the material lattice stress and reduce the large size K + The stress accumulation caused by repeated expansion / contraction between layers during insertion / extraction can maintain structural stability after long cycles and achieve high capacity retention. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 for Na 0.7 Co 0.75 Mn 0.25 X-ray diffraction pattern of O2 porous microcubic material;
[0021] Figure 2 for Na 0.7 Co 0.75 Mn 0.25 SEM image of the product made of O2 porous microcube material;
[0022] Figure 3 for Na 0.7 Co 0.75 Mn 0.25 SEM image of O2 porous microcube material;
[0023] Figure 4 for Na 0.7 Co 0.75 Mn 0.25 TEM image of O2 porous microcube material;
[0024] Figure 5 for Na 0.7 Co 0.75 Mn 0.25 TEM image of O2 porous microcube material;
[0025] Figure 6 for Na 0.7 Co 0.75 Mn 0.25 Co element X-ray photoelectron spectrum of O2 porous microcube material;
[0026] Figure 7 for Na 0.7 Co 0.75 Mn 0.25X-ray photoelectron spectrum of Mn element in O2 porous microcube material;
[0027] Figure 8 This is the Co element X-ray photoelectron spectrum of the material prepared in the comparative example;
[0028] Figure 9 This is the X-ray photoelectron spectrum of the Mn element of the material prepared in the comparative example;
[0029] Figure 10 Electrochemical cycle diagrams of materials prepared in Examples 1 to 3 and the comparative example;
[0030] Figure 11 Graphs showing rate performance of materials prepared in Examples 1 to 3 and the comparative example. DETAILED DESCRIPTION
[0031] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. In the examples, where specific conditions are not specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used where the manufacturer is not specified are conventional products that can be purchased commercially. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. It is obvious to those skilled in the art that various modifications are within the spirit and scope of the present invention as defined and determined by the appended claims, and all inventions and creations utilizing the present invention are protected.
[0032] Example 1
[0033] A method for preparing a microcubic potassium ion battery positive electrode material comprises the following steps:
[0034] S1. Dissolve 7.5 mmol of cobalt acetate, 2.5 mmol of manganese acetate, 1.4 mmol of CTAB, and 50 mmol of urea in 80 mL of deionized water. After stirring, the pH value of the mixture is 9. The mixture is then subjected to a hydrothermal reaction at 200° C. for 15 h. After cooling to room temperature, the mixture is washed with deionized water and anhydrous ethanol, and dried at 80° C. for 12 h to obtain a carbonate precursor.
[0035] S2, the carbonate precursor was placed in a tube furnace and calcined at 500 ° C for 4 hours. Then 1 mmol of the calcined product and 0.735 mmol of sodium hydroxide were dissolved in 5 mL of deionized water, ultrasonically mixed at 1100W for 10 minutes, and then placed in an oven and dried at 80 ° C for 12 hours. Finally, the reactant was placed in a tube furnace and calcined at 850 ° C for 12 hours to obtain Na 0.7 Co 0.75 Mn 0.25 O2 porous microcube material.
[0036] Example 2
[0037] The difference between this embodiment and embodiment 1 is that the amount of CTAB added is adjusted to 0.5 mmol, and the remaining components and preparation steps are the same as those in embodiment 1. 0.7 Co 0.75 Mn 0.25 O2 porous microcube material.
[0038] Example 3
[0039] The difference between this embodiment and embodiment 1 is that the amount of CTAB added is adjusted to 3 mmol, and the remaining components and preparation steps are the same as those in embodiment 1. 0.7 Co 0.75 Mn 0.25 O2 porous microcube material.
[0040] Example 4
[0041] A method for preparing a microcubic potassium ion battery positive electrode material comprises the following steps:
[0042] S1. Dissolve 7 mmol of cobalt sulfate, 2 mmol of manganese sulfate, 3 mmol of CTAC, and 60 mmol of urea in 80 mL of deionized water. Stir the mixture until the pH value is 9.5. Then, subject the mixture to a hydrothermal reaction at 180° C. for 18 h. After cooling to room temperature, rinse with deionized water, and dry at 70° C. for 14 h to obtain a carbonate precursor.
[0043] S2, the carbonate precursor was placed in a tube furnace and calcined at 450 ° C for 5 hours. Then 0.8 mmol of the calcined product and 0.75 mmol of sodium carbonate were dissolved in 5 mL of deionized water, ultrasonically mixed at 1000 W for 15 minutes, and then placed in an oven and dried at 100 ° C for 10 hours. Finally, the reactants were placed in a tube furnace and calcined at 800 ° C for 15 hours to obtain Na 0.7 Co 0.75 Mn 0.25 O2 porous microcube material.
[0044] Example 5
[0045] A method for preparing a microcubic potassium ion battery positive electrode material comprises the following steps:
[0046] S1. Dissolve 8 mmol of cobalt acetate, 3 mmol of manganese sulfate, 0.5 mmol of CTAB, and 40 mmol of urea in 80 mL of deionized water. Stir the mixture until the pH value is 8.5. Then, subject the mixture to a hydrothermal reaction at 220° C. for 12 h. After cooling to room temperature, wash the mixture and dry it at 100° C. for 10 h to obtain a carbonate precursor.
[0047] S2, the carbonate precursor was placed in a tube furnace and calcined at 550 ° C for 3 hours. Then 1.2 mmol of the calcined product and 0.7 mmol of sodium hydroxide were dissolved in 5 mL of deionized water, ultrasonically mixed at 1200W for 5 minutes, and then placed in an oven and dried at 70 ° C for 14 hours. Finally, the reactants were placed in a tube furnace and calcined at 900 ° C for 12 hours to obtain Na 0.7 Co 0.75 Mn 0.25 O2 porous microcube material.
[0048] Comparative Example
[0049] S1. Grind 2.5 mmol of cobalt trioxide, 2.5 mmol of manganese acetate, and 3.675 mmol of sodium carbonate in a mortar for 3 h. Then, place the mixed powder in a muffle furnace and keep it at 850°C for 12 h.
[0050] S2, the calcined powder was taken out and ground for 1 hour, then placed in a muffle furnace and kept at 850 ° C for 12 hours to obtain P2-Na 0.7 Co 0.75 Mn 0.25 O2 bulk material.
[0051] Experimental example
[0052] Taking Example 1 as an example, the materials prepared in Example 1 and the comparative example were observed. Figures 1-9 shown.
[0053] Figure 1 for Na 0.7 Co 0.75 Mn 0.25 X-ray diffraction diagram of O2 porous microcube material, where the black line is the XRD test data of the porous microcube material, and the red line is the PDF card of XRD. Figure 1 It can be seen that the Na prepared by the present invention 0.7 Co 0.75 Mn 0.25 The O2 porous microcube material is of P2 type, which has open triangular prism diffusion channels for alkali metal ions.
[0054] Figure 2 and Figure 3SEM images of the materials prepared in Example 1 and the comparative example are shown. Example 1 shows a porous microcube structure composed of primary particles of 50-150 nm, while the material prepared in Comparative Example 1, using a conventional solid-phase method, is a bulk structure of stacked layers. Compared to conventional bulk stacking structures, the porous microcube structure has a larger specific surface area, enabling more complete contact between the material and the electrolyte. Furthermore, the secondary microcube structure, formed by the accumulation of primary nanoparticles, can alleviate lattice stress accumulated during potassium storage and stabilize the interlayer structure.
[0055] Figure 4 and Figure 5 The TEM images of Example 1 and the comparative example are shown respectively. The d(100) of the material prepared in Example 1 is 0.243 nm, and the d(100) of the material prepared in the comparative example is 0.245 nm, which is consistent with the XRD pattern ( Figure 1 ) shows the P2 type structure; however, the lattice distribution of Example 1 is more uniform, while the lattice distribution of Comparative Example 1 is more distorted. This is because the porous structure of the material of the present invention disperses the stress during the synthesis process, thereby alleviating stress accumulation.
[0056] Figure 6 and Figure 7 The Na 0.7 Co 0.75 Mn 0.25 XPS graphs of Co and Mn elements of O2 porous microcube materials, Figure 8 and Figure 9 The XPS graphs of Co and Mn elements of the materials prepared in the comparative example are shown respectively. 3+ and Mn 3+ Moreover, the radii of the two ions are close, so the lattice distortion is reduced and the structure is more stable during potassium storage.
[0057] Figure 10 The materials prepared in Examples 1 to 3 and the comparative example are shown to have a high -1 The electrochemical cycle diagram below shows that the initial capacities of the four samples are similar, but compared with the comparative example (1000 cycles, capacity retention rate of 72%), the porous microcube structure of Example 1 gives it higher cycle stability (1000 cycles, capacity retention rate of 87%; 4000 cycles, capacity retention rate of 56%). Compared with Example 2 (1000 cycles, capacity retention rate of 69%) and Example 3 (1000 cycles, capacity retention rate of 66%), the adjustment of CTAB can improve the cycle stability of the material.
[0058] Figure 11The rate performance graphs for the materials prepared in Examples 1-3 and the comparative example are presented at different current densities within the voltage range of 1.5-3.9 V. As shown, due to the large specific surface area of the porous microcube morphology synthesized in the present invention, which allows for sufficient contact with the electrolyte and provides more ion transfer channels, Examples 1-3 perform better than Comparative Example 1 at high rates. These results also demonstrate that the material morphology prepared in Example 1 has the most excellent electrochemical performance.
Claims
1. A method for preparing a microcubic potassium ion battery positive electrode material, characterized in that: The following steps are involved: S1. Dissolve a cobalt salt, a manganese salt, and a surfactant in water at a molar ratio of 7-8:2-3:0.5-3, then adjust the pH value of the mixture to 8.5-9.5, and then place the mixture at 180-220° C. for a hydrothermal reaction for 12-18 hours. After cooling to room temperature, wash and dry to obtain a carbonate precursor; S2. The carbonate precursor is calcined at 450-550° C. for a primary time for 3-5 hours, then dissolved in water with a sodium source at a molar ratio of 0.8-1.2:0.7-0.75, dried, and finally the dried product is calcined at 800-900° C. for a secondary time for 12-15 hours to obtain the product.
2. The method for preparing a microcubic potassium ion battery cathode material according to claim 1, wherein: The cobalt salt is cobalt acetate or cobalt sulfate, the manganese salt is manganese acetate or manganese sulfate, and the surfactant is a cationic surfactant.
3. The method for preparing the microcubic potassium ion battery positive electrode material according to claim 1, wherein The surfactant is CTAB or CTAC.
4. The method for preparing the microcubic potassium ion battery positive electrode material according to claim 1, wherein The reagent used to adjust the pH value in S1 is urea.
5. The method for preparing the microcubic potassium ion battery positive electrode material according to claim 1, wherein The cleaning liquid used for the cleaning is deionized water and / or anhydrous ethanol.
6. The method for preparing the microcubic potassium ion battery positive electrode material according to claim 1, wherein The drying temperature in S1 and S2 is 70-100° C., and the drying time is 10-14 hours.
7. The method for preparing the microcubic potassium ion battery positive electrode material according to claim 1, wherein: The sodium source is sodium hydroxide or sodium carbonate.
8. The method for preparing the microcubic potassium ion battery positive electrode material according to claim 1, wherein: The temperature of the primary calcination is 500° C., and the time of the primary calcination is 4 hours; the temperature of the secondary calcination is 850° C., and the time of the primary calcination is 12 hours.
9. A microcubic potassium ion battery positive electrode material, characterized in that: The method is prepared according to any one of claims 1 to 8.
10. The microcubic potassium ion battery positive electrode material according to claim 9, characterized in that The molecular formula of the microcubic potassium ion battery positive electrode material is Na 0.7 Co 0.75 Mn 0.25 O2.