Manganese-doped sodium ferrous sulfate composite positive electrode material and preparation method thereof
By doping manganese ions into sodium ferrous sulfate cathode material and combining it with graphene, the problems of slow charge carrier transport and structural instability were solved, improving the rate performance and cycle stability of the material, making it suitable for high-energy sodium-ion batteries.
Patent Information
- Application Number
- CN202511332005.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-18
- Publication Date
- 2025-12-16
AI Technical Summary
The slow charge carrier transport in sodium ferrous sulfate cathode materials and the Coulombic repulsion between iron ions cause iron migration, leading to structural instability and limiting the rate performance and cycle stability of sodium-ion batteries.
By doping sodium ferrous sulfate with trace amounts of manganese ions and combining it with highly conductive graphene, a three-dimensional conductive network is constructed, which enhances charge carrier transport capability, reduces iron ion migration, and improves structural stability.
The method significantly improves the charge carrier transport rate of sodium ferrous sulfate cathode, enhances its rate performance and cycle stability, meets the requirements of high-energy sodium-ion batteries, and has a simple and low-cost preparation method.
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Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of new energy, and relates to a manganese-doped sodium ferrous sulfate composite positive electrode material and a preparation method thereof. BACKGROUND
[0002] Sodium-ion batteries have a broad application prospect and development potential in large-scale energy storage, portable electronic devices, electric vehicles and other application scenarios due to the rich sodium resources, safety and low-temperature performance better than lithium-ion batteries, and compatibility with the existing lithium-ion battery technology system. As the core key material of sodium-ion batteries, the positive electrode material plays a decisive role in the application performance and the economy of industrialization. Among the existing sodium-ion battery positive electrode materials, polyanion compounds have high structural stability and excellent sodium ion diffusion performance, and exhibit significant advantages in practical application. In particular, sodium ferrous sulfate positive electrode material has become a new type of sodium-ion battery positive electrode material that attracts much attention due to its wide raw material sources, low cost, high working voltage, long cycle life and intrinsic safety.
[0003] Sodium ferrous sulfate has a wide band gap structure, and the intrinsic electronic conductivity is low, which hinders the rapid transmission of charge carriers, significantly limits the reaction kinetics, increases the internal impedance of the battery, and restricts the rate performance of the sodium-ion battery, which becomes a key bottleneck restricting its practical application. In addition, due to the short Fe-Fe spacing in the crystal structure of sodium ferrous sulfate, strong coulomb repulsion is generated, which causes iron ion migration and iron-sodium ion site exchange during the charging process, weakening the structural stability of sodium ferrous sulfate during the charging and discharging process. The traditional carbon coating method can improve the rate performance of the sodium ferrous sulfate positive electrode to some extent by constructing a conductive network, but the intrinsic electronic conductivity of sodium ferrous sulfate is not significantly improved. By doping low electronegative anions such as PO4 3- The Fe-Fe spacing in the crystal structure of sodium ferrous sulfate can be lengthened, the coulomb repulsion in the structure can be reduced, iron migration can be inhibited, and the cycle stability of the material can be improved, but at the same time, the working voltage of the positive electrode is reduced, which restricts the improvement of the energy density of the battery.
[0004] Therefore, it is an urgent need to develop a sodium ferrous sulfate positive electrode with high stability and high rate performance for the development of the next generation of high-energy sodium-ion batteries. SUMMARY
[0005] In view of the problems existing in the prior art, the present application provides a manganese-doped sodium ferrous sulfate composite positive electrode material and a preparation method thereof.The present application aims to improve the charge carrier transport capacity of the sodium ferrous sulfate positive electrode by manganese doping, and to improve the rate performance by compounding with graphene with high conductivity; by using the small coulomb repulsion between manganese ions and iron ions, the problems of irreversible capacity loss and reduced structural stability caused by iron migration are solved, the urgent demand of the next generation of high-energy sodium ion batteries for high-stability and high-rate performance positive electrodes is met, and the application has wide application potential.
[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is:
[0007] A preparation method of a manganese-doped sodium ferrous sulfate composite positive electrode material, the preparation method first disperses sodium sulfate, ferrous sulfate, manganese sulfate, an organic carbon source and graphene oxide in water to form a uniform dispersion liquid. Then, the dispersion liquid is spray dried to obtain a material precursor. Finally, the material precursor is heat treated in an inert atmosphere at high temperature to obtain a manganese-doped sodium ferrous sulfate composite positive electrode material. Specifically comprising the following steps:
[0008] 1) A certain molar ratio of anhydrous sodium sulfate, ferrous sulfate heptahydrate, manganese sulfate, an organic carbon source and graphene oxide are dispersed in deionized water to form a uniform dispersion liquid as a precursor solution.
[0009] The organic carbon source is one or more of citric acid, ascorbic acid or glucose.
[0010] The molar ratio of the anhydrous sodium sulfate, ferrous sulfate heptahydrate, manganese sulfate and organic carbon source is 13:(16-17):(0-1):9, wherein the concentration of anhydrous sodium sulfate in the dispersion liquid is 0.26 mol / L.
[0011] The graphene oxide is a commercial dispersion liquid with a concentration of 10 mg / g in the dispersion liquid.
[0012] 2) The precursor solution prepared in step 1) is spray dried to obtain a material precursor. During the spray drying process, the two metal salts of Na and Fe are atomically dispersed.
[0013] The feed amount of the precursor solution is 200-400 mL / h.
[0014] The outlet temperature of the spray drying is 100-150 DEG C.
[0015] 3) The material precursor prepared in step 2) is heat treated in an inert atmosphere at high temperature to obtain a manganese-doped sodium ferrous sulfate composite positive electrode material. In this step, manganese occupies the iron site in the bulk phase, and sodium ferrous sulfate with alluaudite crystal structure is crystallized out.
[0016] The heat treatment temperature is 350-400 DEG C, and the heat treatment time is 8-10 h.
[0017] The inert gas is hydrogen and argon mixed gas, and the volume ratio of hydrogen and argon is 8:92.
[0018] A manganese-doped sodium ferrous sulfate composite positive electrode material is prepared by the above method; the manganese-doped sodium ferrous sulfate composite positive electrode material has a hollow spherical shell structure, and the average radius is 1-5 mu m.
[0019] The application of the manganese-doped sodium ferrous sulfate composite positive electrode material is applied to the preparation of a high-rate and long-life sodium ion battery.
[0020] Compared with the prior art, the manganese-doped sodium ferrous sulfate composite positive electrode material solves the problems of slow charge carrier transport of the sodium ferrous sulfate positive electrode material and iron migration caused by the Coulomb repulsion force between iron ions, and has the beneficial effects that:
[0021] (1) A small amount of manganese ions is doped in the sodium ferrous sulfate positive electrode material, which significantly improves the charge carrier transport rate.
[0022] (2) A three-dimensional conductive network is constructed by compounding high-conductivity graphene, which further improves the rate performance of the sodium ferrous sulfate positive electrode.
[0023] (3) The small Coulomb repulsion force between manganese ions and iron ions solves the problems of irreversible capacity loss and reduced structural stability caused by iron migration, and improves the cycle stability of the sodium ferrous sulfate positive electrode.
[0024] (4) The preparation method of the manganese-doped sodium ferrous sulfate composite positive electrode material is simple, low in cost, and can be applied to large-scale industrial production.
[0025] In summary, the manganese-doped sodium ferrous sulfate composite positive electrode material can improve the charge carrier transport capacity of the sodium ferrous sulfate positive electrode, and at the same time, the rate performance is improved by compounding with high-conductivity graphene; the small Coulomb repulsion force between manganese ions and iron ions solves the problems of irreversible capacity loss and reduced structural stability caused by iron migration, meets the urgent demand of the next generation of high-energy sodium ion batteries for high-stability and high-rate performance positive electrodes, and has wide application potential. BRIEF DESCRIPTION OF DRAWINGS
[0026] Figure 1 is a scanning electron microscope photo of the manganese-doped sodium ferrous sulfate composite positive electrode material prepared in Example 1 of the present application.
[0027] Figure 2 is an XRD spectrum of the manganese-doped sodium ferrous sulfate composite positive electrode material prepared in Example 1 of the present application.
[0028] Figure 3 is the first cycle capacity-voltage curve of the manganese-doped sodium ferrous sulfate composite positive electrode material prepared in Example 1 of the present application.
[0029] Figure 4 is the coulombic efficiency and cycle stability curve of the manganese-doped sodium ferrous sulfate composite positive electrode material prepared in Example 1 of the present application. DETAILED DESCRIPTION
[0030] In view of the many defects of the prior art, the present inventors have long studied and practiced and have proposed the technical solution of the present application, which will be further explained below in terms of the technical solution, its implementation process and principles. However, it should be understood that, within the scope of the present application, each of the technical features described in the present application and in the following (Examples) can be combined with each other to form a new or preferred technical solution. The materials, reagents, etc. used in the following examples, unless otherwise specified, can be obtained from commercial channels.
[0031] Example 1
[0032] Step 1, 1.846 g of anhydrous sodium sulfate, 4.5592 g of ferrous sulfate heptahydrate, 0.0906 g of manganese sulfate, 0.1584 g of ascorbic acid, and 220 mg of graphene oxide were dispersed in 50 mL of deionized water to form a uniform dispersion.
[0033] The molar ratio of anhydrous sodium sulfate, ferrous sulfate heptahydrate, manganese sulfate, and ascorbic acid is 13:16.4:0.6:9.
[0034] Step 2, after the precursor solution prepared in step 1) is dehydrated by spray drying, a material precursor is obtained. The feed amount of the precursor solution is 200 mL / h, and the outlet temperature of the spray drying is 100 ℃.
[0035] The material precursor prepared in step 2) is heat treated under high temperature conditions in a hydrogen-argon mixed atmosphere to obtain a manganese-doped sodium ferrous sulfate composite positive electrode material. The heat treatment temperature is 400 ℃, and the heating time is 8 h.
[0036] Figure 1 is a scanning electron microscope photograph of the manganese-doped sodium ferrous sulfate composite positive electrode material prepared in Example 1 of the present application, which can be seen to have a spherical morphology.
[0037] Figure 2 is the XRD spectrum of the manganese-doped sodium ferrous sulfate composite positive electrode material prepared in Example 1 of the present application, which can be seen to successfully prepare the manganese-doped sodium ferrous sulfate composite material without impurity phases.
[0038] Figure 3is the first cycle capacity-voltage curve of the manganese-doped sodium ferrous sulfate composite positive electrode material prepared in Example 1 of the present application. A half battery is assembled with sodium metal as the counter electrode for testing. The first discharge specific capacity of the battery is 108 mAh / g at a current density of 0.2 C (1 C = 108 mA / g).
[0039] Figure 4 is the coulombic efficiency and cycle stability curve of the manganese-doped sodium ferrous sulfate composite positive electrode material prepared in Example 1 of the present application. A half battery is assembled with sodium metal as the counter electrode for testing. The capacity retention rate is 99.7% and the average coulombic efficiency is 99.79% after the battery is cycled for 1000 times at a current density of 20 C.
[0040] Example 2
[0041] Step 1, 1.846 g of anhydrous sodium sulfate, 4.726 g of ferrous sulfate heptahydrate, 0 g of manganese sulfate, 0.1584 g of ascorbic acid, and 220 mg of graphene oxide are dispersed in 50 mL of deionized water to form a uniform dispersion.
[0042] The molar ratio of anhydrous sodium sulfate, ferrous sulfate heptahydrate, manganese sulfate, and ascorbic acid is 13:17:0:9.
[0043] Step 2, after the precursor solution prepared in step 1) is dehydrated by spray drying, the material precursor is obtained. The feeding amount of the precursor solution is 250 mL / h, and the outlet temperature of the spray drying is 120 ℃.
[0044] Step 3, the material precursor prepared in step 2) is heat treated under high temperature conditions in a hydrogen-argon mixed atmosphere to obtain a sodium ferrous sulfate composite positive electrode material. The heat treatment temperature is 350 ℃, and the heating time is 9 h.
[0045] In this example, a half battery is assembled with sodium metal as the counter electrode for testing. The first discharge specific capacity of the battery is 92 mAh / g at a current density of 0.2 C. The capacity retention rate is 92.3% and the average coulombic efficiency is 99.53% after the battery is cycled for 1000 times at a current density of 20 C.
[0046] Example 3
[0047] Step 1, 1.846 g of anhydrous sodium sulfate, 4.6704 g of ferrous sulfate heptahydrate, 0.0302 g of manganese sulfate, 0.162 g of glucose, and 220 mg of graphene oxide are dispersed in 50 mL of deionized water to form a uniform dispersion.
[0048] The molar ratio of anhydrous sodium sulfate, ferrous sulfate heptahydrate, manganese sulfate, and glucose is 13:16.8:0.2:9.
[0049] Step 2, the precursor solution prepared in step 1) is dehydrated by spray drying to obtain a material precursor. The feeding amount of the precursor solution is 300 mL / h, and the outlet temperature of the spray drying is 130 ℃.
[0050] 1) The material precursor prepared in step 2) is heat treated under high temperature conditions in a hydrogen-argon mixed atmosphere to obtain a sodium ferrous sulfate composite positive electrode material.
[0051] The heat treatment temperature is 380 ℃, and the heating time is 9 h.
[0052] In this embodiment, a half battery is assembled with sodium metal as the counter electrode for testing. The first discharge specific capacity of the battery is 98.5 mAh / g at a current density of 0.2C. After 1000 cycles at a current density of 20C, the capacity retention rate is 95.4%, and the average coulombic efficiency is 99.65%.
[0053] Example 4
[0054] Step 1, 1.846 g of anhydrous sodium sulfate, 4.448 g of ferrous sulfate heptahydrate, 0.151 g of manganese sulfate, 0.189 g of citric acid, and 220 mg of graphene oxide are dispersed in 50 mL of deionized water to form a uniform dispersion.
[0055] The molar ratio of anhydrous sodium sulfate, ferrous sulfate heptahydrate, manganese sulfate, and citric acid is 13:16:1:9.
[0056] Step 2, the precursor solution prepared in step 1) is dehydrated by spray drying to obtain a material precursor. The feeding amount of the precursor solution is 400 mL / h, and the outlet temperature of the spray drying is 150 ℃.
[0057] Step 3, the material precursor prepared in step 2) is heat treated under high temperature conditions in a hydrogen-argon mixed atmosphere to obtain a sodium ferrous sulfate composite positive electrode material.
[0058] The heat treatment temperature is 370 ℃, and the heating time is 10 h.
[0059] In this embodiment, a half battery is assembled with sodium metal as the counter electrode for testing. The first discharge specific capacity of the battery is 99.1 mAh / g at a current density of 0.2C. After 1000 cycles at a current density of 20C, the capacity retention rate is 96.1%, and the average coulombic efficiency is 99.7%.
[0060] It should be understood that the embodiments described above are merely intended to illustrate the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the present application and to implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and principle of the present application shall be covered within the protection scope of the present application. Although the specific embodiments of the present application are described in combination with the drawings, they are not intended to limit the protection scope of the present application, and those skilled in the art should understand that various modifications or changes made on the basis of the technical solutions of the present application without creative labor are still within the protection scope of the present application.
Claims
1. A method for preparing a manganese-doped sodium ferrous sulfate composite cathode material, characterized in that, The preparation method includes the following steps: The first step involves dispersing sodium sulfate, ferrous sulfate, manganese sulfate, organic carbon source, and graphene oxide in water to form a uniform dispersion, which serves as the precursor solution. The second step is to spray-dry the precursor solution to obtain the material precursor. The third step involves heat-treating the material precursor under high temperature conditions in an inert atmosphere to obtain manganese-doped sodium ferrous sulfate composite cathode material.
2. The method for preparing a manganese-doped sodium ferrous sulfate composite cathode material according to claim 1, characterized in that, In the first step, the organic carbon source is one or more of citric acid, ascorbic acid, or glucose.
3. The method for preparing a manganese-doped sodium ferrous sulfate composite cathode material according to claim 1, characterized in that, In the first step, the molar ratio of anhydrous sodium sulfate, ferrous sulfate heptahydrate, manganese sulfate, and organic carbon source is 13:(16-17):(0-1):9, wherein the concentration of anhydrous sodium sulfate in the dispersion is 0.26 mol / L.
4. The method for preparing a manganese-doped sodium ferrous sulfate composite cathode material according to claim 1, characterized in that, In the first step, the concentration of graphene oxide in the dispersion is 10 mg / g.
5. The method for preparing a manganese-doped sodium ferrous sulfate composite cathode material according to claim 1, characterized in that, In the second step, the feed rate of the precursor solution is 200–400 mL / h.
6. The method for preparing a manganese-doped sodium ferrous sulfate composite cathode material according to claim 1, characterized in that, In the second step, the outlet temperature of the spray dryer is 100–150 °C.
7. The method for preparing a manganese-doped sodium ferrous sulfate composite cathode material according to claim 1, characterized in that, In the third step, the heat treatment temperature is 350-400 ℃ and the heat treatment time is 8-10 h.
8. The method for preparing a manganese-doped sodium ferrous sulfate composite cathode material according to claim 1, characterized in that, In the third step, the inert gas is a hydrogen-argon mixture with a volume ratio of 8:
92.
9. A manganese-doped sodium ferrous sulfate composite cathode material, characterized in that, It is prepared by any one of the preparation methods described in claims 1-8; the manganese-doped sodium ferrous sulfate composite cathode material has a hollow spherical shell structure with an average radius of 1–5 μm.
10. An application of the manganese-doped sodium ferrous sulfate composite cathode material according to claim 9, characterized in that, It is applied to sodium-ion batteries.