Surface coating modification method of Prussian blue analogue sodium ion battery positive electrode material
By forming an aluminum-zirconium composite oxide coating layer on the surface of the Prussian blue analog sodium-ion battery cathode material, the problems of easy structural collapse and low conductivity were solved, and the material achieved high cycle stability and high rate performance.
Patent Information
- Application Number
- CN202510952433.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-10
- Publication Date
- 2025-11-07
AI Technical Summary
Prussian blue analogue sodium-ion battery cathode materials suffer from problems such as structural collapse, poor cycle stability, and low electronic conductivity in practical applications. Existing surface modification methods have weak adhesion, poor uniformity, and complex processes.
An aluminum-zirconium composite oxide coating layer was formed on the surface of Prussian blue analogues using an in-situ non-hydrolyzed sol-gel method. The coating layer was strongly bonded to PBA particles through Al-O-Fe/Zn and Zr-OC≡N chemical bonds, forming an amorphous coating layer that blocked electrolyte erosion and buffered volume changes, thereby improving cycle stability and electronic conductivity.
It significantly improves the cycle stability and high-rate charge-discharge performance of the material, with cycle stability improved by more than 40%, capacity retention at 2C rate ≥85%, and improved electron and ion transport efficiency.
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Figure CN120903556A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application relates to the technical field of sodium ion battery materials, in particular to a surface coating modification method of a Prussian blue analogue sodium ion battery positive electrode material. BACKGROUND
[0002] Sodium ion batteries have broad application prospects in large-scale energy storage fields due to low cost and rich resources. As a positive electrode material of sodium ion batteries, Prussian blue analogues (PBA) have the advantages of high theoretical capacity and simple synthesis process, but have obvious defects in practical application. The crystal water in the PBA structure is easy to remain, which causes the active sites to be eroded by water molecules in the electrolyte, and causes the structure to collapse. At the same time, the volume change in the sodium ion insertion / extraction process will cause the particles to be pulverized, resulting in a decrease in cycle stability. In addition, the intrinsic electronic conductivity of PBA is low, and the ion transmission resistance increases during high-rate charging and discharging, which seriously affects the rate performance.
[0003] Although the existing surface modification method can improve the performance of PBA to a certain extent, there are still problems such as weak adhesion between the coating layer and the substrate, poor uniformity, and complex process. For example, the traditional oxide coating layer is mostly attached to the surface of PBA through simple physical adsorption, which is easy to fall off during the cycle process, and cannot form a strong chemical bond. Some sol-gel methods require harsh hydrolysis conditions, and it is difficult to accurately control the thickness and composition of the coating layer. SUMMARY
[0004] In order to overcome the deficiencies of the prior art, the application provides a surface coating modification method of a Prussian blue analogue sodium ion battery positive electrode material, which can effectively solve the problems in the background art.
[0005] The technical scheme adopted by the application to solve the technical problems is:
[0006] A surface coating modification method of a Prussian blue analogue sodium ion battery positive electrode material, comprising the following steps:
[0007] Step S1: Preparation of a precursor solution: dissolve an aluminum source and a zirconium source in an organic solvent, add a chelating agent, and form a uniform and stable mixed solution;
[0008] Step S2: Pretreatment of the substrate: disperse the Prussian blue analogue (PBA) positive electrode material in an aprotic polar solvent, and ultrasonically treat to obtain a dispersion liquid;
[0009] Step S3: In-situ non-hydrolytic sol-gel coating: add the mixed solution of step S1 dropwise into the dispersion liquid of step S2, stir and react under an inert atmosphere, control the reaction temperature to be 50-80 DEG C, and the reaction time is 2-6 hours;
[0010] Step S4: heat treatment molding: after centrifugal washing of the product obtained in step S3, calcination at 200-400℃ for 2-5 hours to obtain a modified PBA material with a surface coated aluminum-zirconium composite oxide layer;
[0011] wherein the molar ratio of Al:Zr in the aluminum-zirconium composite oxide layer is (1:1)-(4:1), and the thickness of the coating layer is 5-50 nm.
[0012] As a further description of the above technical solution, the aluminum source is at least one of aluminum isopropoxide and aluminum sec-butoxide; the zirconium source is at least one of zirconium isopropoxide and zirconium n-butoxide; the organic solvent is ethanol, isopropyl alcohol or tetrahydrofuran; the chelating agent is at least one of acetylacetone and acetic acid, and its molar amount is 10-30% of the total molar amount of the aluminum source and the zirconium source.
[0013] As a further description of the above technical solution, the concentration of the mixed solution in step S1 is 0.05-0.3 mol / L.
[0014] As a further description of the above technical solution, in step S2:
[0015] the aprotic polar solvent is N-methyl pyrrolidone (NMP) or dimethyl sulfoxide (DMSO);
[0016] the mass-volume ratio of the PBA material to the solvent is 1 g:(50-200) mL.
[0017] As a further description of the above technical solution, in step S3:
[0018] the dropwise addition rate is 1-5 mL / min;
[0019] the stirring rate is 300-800 rpm;
[0020] the inert atmosphere is nitrogen or argon.
[0021] As a further description of the above technical solution, in step S3, the pH value of the system after reaction is controlled at 4.0-6.0.
[0022] As a further description of the above technical solution, in step S4, the calcination process adopts programmed temperature rising:
[0023] First stage: temperature rising at 2-5℃ / min to 100-150℃, and holding for 0.5-1 hour;
[0024] Second stage: temperature rising at 3-8℃ / min to the target temperature (200-400℃).
[0025] As a further description of the above technical scheme, the aluminum-zirconium composite oxide layer is in an amorphous state and is combined with the surface of the PBA particles through Al-O-Fe / Zn and Zr-O-C≡N chemical bonds.
[0026] As a further description of the above technical scheme, the coating layer completely covers the surface of the PBA particles without exposed areas; the cycle stability of the modified material is improved by greater than or equal to 40% (1C rate, capacity retention rate after 200 cycles); and the capacity retention rate at 2C rate is greater than or equal to 85% (compared with the initial capacity at 0.1C).
[0027] A sodium ion battery, the positive electrode of which adopts the surface-coated modified Prussian blue analog positive electrode material.
[0028] Compared with the prior art, the present application has the following beneficial effects:
[0029] The surface-coating modification method of the Prussian blue analog sodium ion battery positive electrode material has at least one of the following beneficial effects in use:
[0030] A uniform and dense aluminum-zirconium composite oxide coating layer is formed on the surface of the Prussian blue analog through in-situ non-hydrolytic sol-gel method and controllable heat treatment. The amorphous coating layer is strongly combined with the PBA particles through Al-O-Fe / Zn and Zr-O-C≡N chemical bonds, completely covers the surface of the particles (without exposed areas), effectively blocks the electrolyte corrosion, buffers the volume change caused by sodium ion intercalation / deintercalation, and reduces particle pulverization and structure collapse. The cycle stability of the modified material is improved by greater than or equal to 40% (1C rate, 200 cycles), the capacity retention rate at 2C rate is greater than or equal to 85% (compared with the initial capacity at 0.1C), the high-rate charge-discharge performance is significantly improved, the interface resistance is reduced, and the electron and ion transport efficiency is improved. By adjusting the aluminum-zirconium molar ratio (1:1-4:1), the coating layer thickness (5-50nm), and the calcination procedure, the composition and structure of the coating layer can be precisely controlled, the process conditions are mild and the steps are simple, and the method is suitable for industrial large-scale production, thereby providing an efficient solution for modification of sodium ion battery positive electrode materials. BRIEF DESCRIPTION OF DRAWINGS
[0031] Figure 1 The preparation process flow chart of the surface-coating modification method of the Prussian blue analog sodium ion battery positive electrode material is shown in the figure. DETAILED DESCRIPTION
[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.
[0033] As shown in Figure 1 The present application provides a surface coating modification method of a Prussian blue analogue sodium ion battery positive electrode material, comprising the following steps:
[0034] Step S1: Preparation of precursor solution: Dissolve aluminum and zirconium sources in an organic solvent, add a chelating agent to form a uniform and stable mixed solution;
[0035] Step S2: Pretreatment of the substrate: Disperse the Prussian blue analogue (PBA) positive electrode material in an aprotic polar solvent, and obtain a dispersion liquid by ultrasonic treatment;
[0036] Step S3: In-situ non-hydrolytic sol-gel coating: Add the mixed solution of step S1 dropwise to the dispersion liquid of step S2, stir the reaction under an inert atmosphere, control the reaction temperature to be 50-80°C, and the reaction time to be 2-6 hours;
[0037] Step S4: Heat treatment and molding: After centrifugal washing of the product obtained in step S3, calcine at 200-400°C for 2-5 hours to obtain a modified PBA material with a surface coated aluminum-zirconium composite oxide layer;
[0038] The molar ratio of Al:Zr in the aluminum-zirconium composite oxide layer is (1:1)-(4:1), and the thickness of the coating layer is 5-50 nm.
[0039] The aluminum-zirconium composite oxide coating layer completely covers the surface of the PBA particles without exposed areas, forming a physical barrier that effectively blocks water molecules and other impurities in the electrolyte from directly contacting the PBA particles, reducing the erosion of the electrolyte on the PBA structure, thereby improving the structural stability of the material. The amorphous coating layer structure has good flexibility and adaptability, which can buffer the volume change of the PBA particles during the sodium ion insertion / extraction process, reduce the breakage and pulverization of the particles, and further improve the cycle stability of the material.
[0040] After modification, the capacity retention rate of the material at 1C rate after 200 cycles is increased by ≥40%. This is because the coating layer inhibits the corrosion of the electrolyte on the PBA particles, reduces the loss of active material, and at the same time enhances the stability of the electron conduction and ion transport path between the particles, so that the battery can maintain a high capacity during long-term cycling.
[0041] The modification method can precisely control the composition, structure and thickness of the coating layer by controlling the molar ratio of the aluminum source and the zirconium source (1:1-4:1), the thickness of the coating layer (5-50 nm), the reaction temperature, the time, the dropping speed, the stirring speed and the calcination procedure, and realizes the optimization of the modification effect of the PBA material. The process steps are simple and the conditions are mild.
[0042] The coating layer and the PBA particle surface are combined by Al-O-Fe / Zn and Zr-O-C≡N chemical bonds, forming good interfacial compatibility, reducing the interfacial resistance, and promoting the transmission of electrons between the electrode material and the electrode / electrolyte interface. This strong chemical bond also reduces the shedding and peeling of the coating layer during the charging and discharging process, ensuring the long-term effectiveness of the coating layer and further improving the overall performance of the battery.
[0043] The capacity retention rate at 2C rate is ≥85% (compared with the initial capacity at 0.1C). The presence of the coating layer improves the electronic conductivity and ion diffusion rate of the PBA particle surface, allowing sodium ions to migrate faster in the electrode material, even under high-rate charging and discharging conditions, and maintaining good electrochemical reaction activity, thereby improving the rate performance of the material.
[0044] Further, the aluminum source is at least one of aluminum isopropoxide and aluminum sec-butoxide; the zirconium source is at least one of zirconium isopropoxide and zirconium n-butoxide; the organic solvent is ethanol, isopropyl alcohol or tetrahydrofuran; and the chelating agent is at least one of acetylacetone and acetic acid, and the molar amount of the chelating agent is 10-30% of the total molar amount of the aluminum source and the zirconium source.
[0045] The aluminum source (such as aluminum isopropoxide and aluminum sec-butoxide) and the zirconium source (such as zirconium isopropoxide and zirconium n-butoxide) are dissolved in an organic solvent (ethanol, isopropyl alcohol or tetrahydrofuran), and a chelating agent (acetylacetone, acetic acid, etc.) is added. The molar amount of the chelating agent is 10-30% of the total molar amount of the aluminum source and the zirconium source, which forms a stable chelate complex with aluminum and zirconium ions, inhibits the hydrolysis reaction of metal ions, controls the release speed of metal ions in the subsequent reaction, and thus forms a uniform and stable mixed solution, providing a stable source of metal ions for the subsequent sol-gel reaction.
[0046] The precursor mixed solution is added dropwise into the PBA dispersion under an inert atmosphere (nitrogen or argon), the dropwise rate is controlled to be 1-5 mL / min, the stirring rate is 300-800 rpm, the reaction temperature is 50-80℃, and the reaction time is 2-6 hours. Under this condition, the aluminum and zirconium chelate complexes in the precursor solution gradually release metal ions, which undergo non-hydrolytic sol-gel reaction with the active sites on the surface of the PBA particles (such as Fe / Zn atoms and C≡N groups). As the reaction proceeds, the metal ions gradually condense to form a sol, which is then converted into a gel, forming an initial aluminum-zirconium composite oxide coating layer on the surface of the PBA particles. The pH value of the reaction system is controlled at 4.0-6.0, and a suitable pH value environment is conducive to the sol-gel reaction and promotes the uniform formation of the coating layer. The inert atmosphere prevents the oxidation of metal ions and PBA materials, ensuring the smooth progress of the reaction.
[0047] Further, the concentration of the mixed solution in step S1 is 0.05-0.3 mol / L.
[0048] As a further description of the above technical solution, in step S2:
[0049] The aprotic polar solvent is N-methyl pyrrolidone (NMP) or dimethyl sulfoxide (DMSO);
[0050] The mass-volume ratio of the PBA material to the solvent is 1 g:(50-200) mL.
[0051] Further, in step S3:
[0052] The dropwise rate is 1-5 mL / min;
[0053] The stirring rate is 300-800 rpm;
[0054] The inert atmosphere is nitrogen or argon.
[0055] Further, the pH value of the reaction system after step S3 is controlled at 4.0-6.0.
[0056] Further, in step S4, the calcination process adopts programmed temperature rise:
[0057] First stage: temperature rise at 2-5℃ / min to 100-150℃, holding for 0.5-1 hour;
[0058] Second stage: temperature rise at 3-8℃ / min to the target temperature (200-400℃).
[0059] Further, the aluminum-zirconium composite oxide layer is in an amorphous structure and is combined with the surface of the PBA particles through Al-O-Fe / Zn and Zr-O-C≡N chemical bonds.
[0060] Further, the coating layer completely covers the surface of the PBA particles without exposed areas; the cycle stability of the modified material is improved by 40% or more (1C rate, capacity retention rate after 200 cycles); and the capacity retention rate at 2C rate is 85% or more (compared with the initial capacity at 0.1C).
[0061] The PBA positive electrode material is dispersed in an aprotic polar solvent (N-methyl pyrrolidone (NMP) or dimethyl sulfoxide (DMSO)), and ultrasonic treatment is performed to fully disperse the PBA particles, thereby obtaining a uniform dispersion liquid. The aprotic polar solvent can effectively disperse the PBA particles and avoid particle agglomeration, and the ultrasonic treatment further destroys the agglomeration force between the particles, increases the specific surface area of the PBA particles, and provides a good substrate surface for the subsequent in-situ coating reaction, so that the coating layer can be uniformly deposited on the surface of the PBA particles.
[0062] A sodium ion battery, wherein the positive electrode uses the surface-coated modified Prussian blue analog positive electrode material.
[0063] After centrifugal washing of the coated product, programmed temperature calcination is performed. In the first stage, the temperature is raised to 100-150°C at a rate of 2-5°C / min, and the temperature is kept constant for 0.5-1 hour. In this stage, the residual solvent and low-boiling-point impurities are removed, and the coating layer is preliminarily solidified. In the second stage, the temperature is raised to 200-400°C at a rate of 3-8°C / min, and the calcination is performed at the target temperature for 2-5 hours, so that the aluminum-zirconium composite oxide coating layer is further dehydrated and condensed to form a stable amorphous structure. During the calcination process, the surface of the PBA particles and the coating layer are combined through Al-O-Fe / Zn and Zr-O-C≡N chemical bonds. The formation of the chemical bonds enhances the bonding force between the coating layer and the PBA particles, so that the coating layer can be firmly attached to the surface of the PBA particles to form a complete coating layer.
[0064] It will be obvious to a person skilled in the art that the application is not limited to the details of the above-described exemplary embodiments, but that the application can be implemented in other concrete forms without departing from the spirit or essential characteristics of the application. Therefore, the embodiments should be considered as exemplary and not limiting in any way. The scope of the application is defined by the claims appended hereto rather than by the description given above, and therefore all changes coming within the meaning and range of equivalents of the claims are intended to be embraced therein. Any reference signs in the claims should not be construed as limiting the claims concerned.
Claims
1. A surface coating modification method of a Prussian blue analogue sodium-ion battery cathode material, characterized by , comprising the following steps: Step S1: Preparation of precursor solution: Dissolve aluminum source and zirconium source in organic solvent, add chelating agent to form a uniform and stable mixed solution; Step S2: Substrate pretreatment: Disperse Prussian blue analog (PBA) positive electrode material in an aprotic polar solvent, and obtain a dispersion liquid by ultrasonic treatment; Step S3: In-situ non-hydrolytic sol-gel coating: Add the mixed solution of step S1 dropwise into the dispersion liquid of step S2, stir the reaction under inert atmosphere, control the reaction temperature at 50-80℃, and the reaction time is 2-6 hours; Step S4: Heat treatment and molding: After centrifugal washing of the product obtained in step S3, calcine at 200-400℃ for 2-5 hours to obtain a modified PBA material with a surface coated aluminum-zirconium composite oxide layer; Wherein, the molar ratio of Al:Zr in the aluminum-zirconium composite oxide layer is (1:1)-(4:1), and the thickness of the coating layer is 5-50nm.
2. The surface coating modification method of a Prussian blue analog sodium ion battery positive electrode material according to claim 1, characterized in that: The aluminum source is at least one of aluminum isopropoxide and aluminum sec-butoxide; The zirconium source is at least one of zirconium isopropoxide and zirconium n-butoxide; The organic solvent is ethanol, isopropyl alcohol or tetrahydrofuran; The chelating agent is at least one of acetylacetone and acetic acid, and the molar amount is 10-30% of the total molar amount of the aluminum source and the zirconium source.
3. The surface coating modification method of a Prussian blue analogue sodium-ion battery cathode material according to claim 1, characterized in that: The concentration of the mixed solution in step S1 is 0.05-0.3 mol / L. The aprotic polar solvent in step S2 is N-methyl pyrrolidone (NMP) or dimethyl sulfoxide (DMSO); 4. The surface coating modification method of a Prussian blue analogue sodium-ion battery cathode material according to claim 1, characterized in that: The mass-volume ratio of the PBA material to the solvent is 1g:(50-200)mL. The dropwise addition rate in step S3 is 1-5mL / min; The stirring rate is 300-800rpm; 5. The surface coating modification method of a Prussian blue analogue sodium-ion battery cathode material according to claim 1, characterized in that: The inert atmosphere is nitrogen or argon. The pH value of the system after the reaction in step S3 is controlled at 4.0-6.
0. The calcination process in step S4 adopts programmed temperature rising: First stage: rise to 100-150℃ at a rate of 2-5℃ / min, and keep the temperature for 0.5-1 hour; 6. The surface coating modification method of a Prussian blue analogue sodium-ion battery cathode material according to claim 1, characterized in that: Second stage: rise to the target temperature (200-400℃) at a rate of 3-8℃ / min.
7. The surface coating modification method of a Prussian blue analog sodium-ion battery cathode material according to claim 1, characterized in that: The aluminum-zirconium composite oxide layer is in an amorphous state and is combined with the surface of the PBA particles through Al-O-Fe / Zn and Zr-O-C≡N chemical bonds.
9. The surface-coated and modified Prussian blue analog positive electrode material prepared by the method of any one of claims 1-8, characterized in that: The coating layer completely covers the surface of the PBA particles without exposed areas; 8. The surface coating modification method of a Prussian blue analogue sodium-ion battery cathode material according to claim 1, characterized in that: The cycle stability of the modified material is improved by ≥40% (1C rate, capacity retention rate after 200 cycles); The capacity retention rate at 2C rate is ≥85% (compared to the initial capacity at 0.1C). The positive electrode uses the surface-coated and modified Prussian blue analog positive electrode material of claim 9. 10. A sodium-ion battery, characterized in that: