Preparation method, product and application of doped purple moon-shaped iron oxide

Abstract

The invention discloses a preparation method of doped purple moon-shaped iron oxide, which comprises the following steps: (1) taking DMF (Dimethyl Formamide), an iron source and 2-aminoterephthalic acid as reaction raw materials, taking acetic acid as a solvent, and carrying out hydrothermal reaction to obtain Fe-MIL-88NH2; (2) Fe-MIL-NH2 and absolute ethyl alcohol are used as reaction raw materials, ultrasonic dispersion is performed, and a solution A is obtained; (3) by taking (NH4) 2MoO4, absolute ethyl alcohol and deionized water as reaction raw materials, carrying out ultrasonic dispersion to obtain a solution B; and (4) rapidly pouring the solution A obtained in the step (2) into the solution B obtained in the step (3) in a water bath stirring process, stirring, and carrying out high-temperature calcination in an air atmosphere to synthesize doped purple moon-shaped iron oxide which is marked as Fe-MIL-88NH2-Mo. The invention also discloses the purple-moon-shaped iron oxide obtained by the preparation method and application of the purple-moon-shaped iron oxide in a zinc ion battery. The application of the prepared purple-moon-shaped iron oxide in the zinc ion battery shows high specific capacity, high energy density and excellent cycle performance at the same time.

Description

Technical Field

[0001] The present invention belongs to the application field of cathode materials for zinc-ion batteries and the preparation technology of birnessite, and specifically relates to a preparation method, product and application of a doped purple moon-shaped iron oxide. Background Art

[0002] In today's rapidly changing energy storage technology, lithium-ion batteries are a major component of the new energy field. With their unique advantages and challenges, they are leading the innovation and development of battery technology. However, as time goes by, their drawbacks have become increasingly prominent. Lithium-ion batteries have high costs due to the high price of cathode materials and the difficulty in purifying the electrolyte system, and there are also safety hazards and environmental pollution. For example, ternary lithium batteries are prone to thermal runaway and explosion; lithium iron phosphate batteries have a relatively low energy density and a slow charging speed; lithium cobalt oxide batteries have a high cost and are prone to thermal runaway and fire. In addition to lithium-ion batteries, sodium-ion batteries also account for a certain proportion in the battery market, but their disadvantages are also becoming increasingly prominent. The most serious one is that they are relatively large in size, have a relatively low energy density, a short lifespan, and will also cause certain pollution to the environment. Solid-state batteries have defects such as large size and being not easy to carry.

[0003] In contrast, zinc-ion batteries have become one of the most promising electrochemical energy storage devices due to their high energy density, low cost, environmental friendliness, safety and other advantages. The practical application of zinc-ion batteries is troubled by cathode obstacles. For example, the cycle stability is poor, and the cathode materials for zinc-ion batteries mainly include manganese-based oxides, vanadium-based oxides, Prussian blue analogs and organic compounds. Since zinc metal is non-toxic and environmentally friendly and can stably exist in neutral aqueous solutions, zinc-ion batteries with a long cycle life have become one of the most promising candidate devices. At present, doped materials as cathode materials for zinc-ion batteries have attracted much attention: "Research Progress of Cathode Materials for Aqueous Zinc-Ion Batteries" (Wang Peng, Zhang Guilin, Tang Jingjing, etc. Research Progress of Cathode Materials for Aqueous Zinc-Ion Batteries [J]. Nonferrous Metallurgical Equipment, 2024, 38(3): 1-9) publicly reported that Wang et al. obtained through a large number of studies that by an appropriate cation doping strategy, the structural stability and capacity structure and other properties of the cathode material can be improved, so that the zinc-ion battery can still remain stable after 20,000 cycles; for example, Chinese Patent with the publication number CN113782727A discloses a doped cathode material for zinc-ion batteries. By dissolving a vanadium source, an oxidant, a fuel and a cation doping raw material in water and mixing them evenly to obtain a mixed phase, and subjecting the mixed phase to a low-temperature combustion reaction to obtain the doped cathode material for zinc-ion batteries.

[0004] Although doping technology has been widely applied, it is still a difficult problem to achieve excellent cycling performance while maintaining a high specific capacity of the material. There has been no report on the preparation of cathode materials for zinc-ion batteries with high specific capacity, high energy density, and high cycling performance through simple methods. Summary of the Invention

[0005] The object of the present invention is to provide a preparation method of doped purple moon-shaped iron oxide. The prepared Fe-MIL-88NH2-Mo has a uniform purple moon morphology and simultaneously exhibits high specific capacity, high energy density, and excellent cycling performance in the application of zinc-ion batteries.

[0006] To achieve the above invention object, the technical solution provided by the present invention is as follows:

[0007] A preparation method of doped purple moon-shaped iron oxide, the preparation method comprising the following steps:

[0008] (1) Using DMF, an iron source, and 2-aminoterephthalic acid as reaction raw materials, and acetic acid as a solvent, performing a hydrothermal reaction to obtain Fe-MIL-88NH2;

[0009] (2) Using Fe-MIL-NH2 and absolute ethanol as reaction raw materials, performing ultrasonic dispersion to obtain solution A;

[0010] (3) Using (NH4)2MoO4, absolute ethanol, and deionized water as reaction raw materials, performing ultrasonic dispersion to obtain solution B;

[0011] (4) Pouring solution A in step (2) into solution B in step (3) during water bath stirring, stirring, and performing high-temperature calcination in an air atmosphere to synthesize doped purple moon-shaped iron oxide, denoted as Fe-MIL-88NH2-Mo.

[0012] The technical principle of the present invention lies in: By precisely controlling the doping ratio of transition metal ions, a purple moon-shaped material with a three-dimensional pillar structure is successfully synthesized through a one-step solution method at room temperature; this special morphology greatly expands the contact interface between the material and the electrolyte, and the specific surface area is significantly improved compared with traditional materials, providing more abundant reaction active sites for zinc ions; at the same time, the lattice distortion effect of the doped ions is utilized to construct a nanoscale pillar network with a diameter of about 50-80 nm inside the material, effectively suppressing the volume expansion of the traditional layered structure during charge and discharge; thus, it is beneficial to significantly improve the rate performance and cycling stability of zinc-ion batteries.

[0013] In step (1), the volume of the DMF is 1 mL to 30 mL, the molar mass of the iron source is 0.1 to 2 mmol, the molar mass of 2-aminoterephthalic acid is 0.1 to 2 mmol, and the acetic acid is 1 to 10 mL.

[0014] The iron source is selected from one or more of iron chloride, iron nitrate, iron sulfate or potassium ferrocyanide.

[0015] In step (1), the hydrothermal reaction temperature is 100-140 °C, the hydrothermal reaction time is 2-6 hours, and the stirring time is 5-30 minutes.

[0016] In step (2), the mass of the Fe-MIL-88NH2 is 30-70 mg, the volume of absolute ethanol is 1-20 mL; the ultrasonic dispersion time is 1-10 minutes.

[0017] In step (3), the molar mass of (NH4)2MoO4 is 0.1-0.36 mol, the volume of deionized water is 20-60 mL; the ultrasonic dispersion time is 1-10 minutes.

[0018] In step (4), the water bath stirring temperature is 60-100 °C, the stirring time is 1-20 min; the high-temperature calcination temperature is 400-500 °C, and the high-temperature calcination time is 1-5 hours.

[0019] Preferably, in solution A in step 1), acetic acid is 2-5 mL, and in solution B in step 2), absolute ethanol is 1-18 mL.

[0020] Preferably, in step 1), the volume of DMF is 1 mL-22 mL, the molar mass of FeCl3 is 0.1-1.4 mmol, and the molar mass of aminoterephthalic acid is 0.1-1.2 mmol. Preferably, in step 2), the mass of Fe-MIL-88NH2 is 30-55 mg, and in step 3), the molar mass of (NH4)2MoO4 is 0.1-0.3 mol.

[0021] Preferably, the molar mass of FeCl3 is 0.7 mmol, the mass of Fe-MIL-88NH2 is 50 mg, and the molar mass of (NH4)2MoO4 is 0.1-0.3 mol; further, the molar mass of (NH4)2MoO4 is 0.1-0.2 mol; further, the molar mass of (NH4)2MoO4 is 0.1-0.15 mol. By regulating the content of the doped ions, the rate performance and cycle stability of its application in zinc ion batteries are regulated.

[0022] The present invention also provides a doped purple moon-shaped iron oxide Fe-MIL-88NH2-Mo obtained by the above preparation method.

[0023] In the Fe-MIL-88NH2-Mo, the molar mass content of the Mo element > 0.1%; the morphology of the Fe-MIL-88NH2-Mo is purple moon-shaped.

[0024] The present invention also provides an application of the above Fe-MIL-88NH2-Mo in the preparation of zinc ion batteries.

[0025] When used in zinc ion batteries, with the doped purple moon-shaped iron oxide as the positive electrode and the zinc sheet as the negative electrode, the voltage range can be extended to 1.8 V, and the highest electrochemical performance can reach: the specific capacity can reach 307 mAh g -1 , and the maximum energy density is 225.56 Wh kg -1 , and the maximum power density is 16.12 kW kg -1 , and when the current density is 20 Ag -1 , the capacity retention rate is 94% after 2000 cycles of charge and discharge.

[0026] The beneficial effects of the present invention are embodied in:

[0027] (1) The preparation method in the present invention has low cost, is environmentally friendly, requires less equipment investment, is simple to operate, has small batch differences, and is suitable for large-scale production.

[0028] (2) The doped purple moon-shaped iron oxide prepared by the present invention has a special and uniform purple moon-shaped morphology.

[0029] (3) The doped purple moon-shaped iron oxide prepared by the present invention is used as the positive electrode of the zinc ion battery, and the zinc sheet is used as the negative electrode of the zinc ion battery. When assembled into a button battery device, it exhibits good electrochemical performance. Description of the Drawings

[0030] Figure 1 It is the XRD pattern of the product prepared in Example 1 measured by the D8 type X-ray diffractometer of Bruker Corporation in the United States, where: the abscissa X is the diffraction angle (2θ), and the ordinate Y is the relative diffraction intensity.

[0031] Figure 2 It is the morphology diagram of the purple moon-shaped iron oxide prepared in Example 1 observed by the S-4800 type field emission scanning electron microscope (FE-SEM) of Hitachi Corporation in Japan.

[0032] Figure 3 It is the morphology diagram of the purple moon-shaped iron oxide prepared in Example 1 observed by the S-4800 type field emission scanning electron microscope (FE-SEM) of Hitachi Corporation in Japan.

[0033] Figure 4 It is the constant current charge and discharge curve of the button battery assembled with the purple moon-shaped iron oxide prepared in Example 1 tested by the CT3001A electrochemical workstation of Wuhan Blue Electric Co., Ltd.

[0034] Figure 5It is the cycle performance of the button battery for preparing purple moon-shaped iron oxide in Test Example 1 of the CT3001A electrochemical workstation of Wuhan Blue Electric Co., Ltd. Detailed implementation mode

[0035] The above content of the present invention will be further described in detail through the following examples. However, it should not be understood that the scope of the above subject matter of the present invention is limited to the following examples. All technologies implemented based on the above content of the present invention belong to the scope of the present invention.

[0036] Example 1

[0037] (1) Using 15 mL of DMF, 0.7 mmol of FeCl3, and 0.7 mmol of 2-aminoterephthalic acid as reaction raw materials, stirring for 15 min, adding 10 mL of acetic acid as a solvent, and performing a hydrothermal reaction at 120 °C for 4 h. After centrifugal washing and drying at 70 °C, Fe-MIL-88NH2 is obtained;

[0038] (2) Using 50 mg of Fe-MIL-NH2 and 10 mL of absolute ethanol as reaction raw materials, ultrasonic dispersing for 3 min to obtain solution A;

[0039] (3) Using 0.15 mol of (NH4)2MoO4, 10 mL of absolute ethanol, and 40 mL of deionized water as reaction raw materials, ultrasonic dispersing for 3 min to obtain solution B;

[0040] (4) Rapidly pouring solution A in step (2) into solution B in step (3) during stirring in a water bath at 85 °C, stirring for 10 min, centrifugal washing and drying at 70 °C, and performing high-temperature calcination at 450 °C for 4 h in an air atmosphere to synthesize Fe-MIL-88NH2-Mo.

[0041] Figure 1 is the XRD pattern of the product prepared in Example 1, where: the abscissa X is the diffraction angle (2θ), and the ordinate Y is the relative diffraction intensity; Figure 2 is the morphology diagram of the purple moon-shaped iron oxide prepared in Example 1 observed by field emission scanning electron microscopy (FE-SEM); Figure 3 is the morphology diagram of the purple moon-shaped iron oxide prepared in Example 1 observed by field emission scanning electron microscopy (FE-SEM). And it can be seen from Figure 2-3 that the material has a nanoscale pillar network with a diameter of about 50-80 nm inside.

[0042] Transmission electron microscopy shows that the synergistic effect of the purple moon-shaped morphology and the pillar structure increases the specific surface area of the material to 125 m 2 / g provides more active sites and transport channels for zinc ions. In addition, the defect structure formed by doping optimizes the electronic conductivity, reducing the charge transfer resistance of the material to 35.2 Ω, significantly improving the rate performance and cycling stability of the battery.

[0043] Comparative Example 1

[0044] (1) Using 15 mL of DMF, 0.7 mmol of FeCl3, and 0.7 mmol of 2-aminoterephthalic acid as reaction raw materials, stirring for 15 min, adding 10 mL of acetic acid as a solvent, and performing hydrothermal reaction at 120 °C for 4 h. After centrifugal washing and drying at 70 °C, Fe-MIL-88NH2 was obtained;

[0045] (2) Using 50 mg of Fe-MIL-NH2 and 10 mL of absolute ethanol as reaction raw materials, ultrasonic dispersion for 3 min to obtain Solution A;

[0046] (3) Using 0.05 mol of (NH4)2MoO4, 10 mL of absolute ethanol, and 40 mL of deionized water as reaction raw materials, ultrasonic dispersion for 3 min to obtain Solution B;

[0047] (4) During the 85 °C water bath stirring of Solution A in step (2), quickly pour it into Solution B in step (3), stir for 10 min, perform centrifugal washing and drying at 70 °C, and calcine at 450 °C for 4 h in an air atmosphere to synthesize Fe-MIL-88NH2-0.05Mo.

[0048] Example 2

[0049] (1) Using 15 mL of DMF, 0.7 mmol of FeCl3, and 0.7 mmol of 2-aminoterephthalic acid as reaction raw materials, stirring for 15 min, adding 10 mL of acetic acid as a solvent, and performing hydrothermal reaction at 120 °C for 4 h. After centrifugal washing and drying at 70 °C, Fe-MIL-88NH2 was obtained;

[0050] (2) Using 50 mg of Fe-MIL-NH2 and 10 mL of absolute ethanol as reaction raw materials, ultrasonic dispersion for 3 min to obtain Solution A;

[0051] (3) Using 0.1 mol of (NH4)2MoO4, 10 mL of absolute ethanol, and 40 mL of deionized water as reaction raw materials, ultrasonic dispersion for 3 min to obtain Solution B;

[0052] (4) During the 85 °C water bath stirring of Solution A in step (2), quickly pour it into Solution B in step (3), stir for 10 min, perform centrifugal washing and drying at 70 °C, and calcine at 450 °C for 4 h in an air atmosphere to synthesize Fe-MIL-88NH2-0.1Mo.

[0053] Example 3

[0054] (1) Using 15 mL of DMF, 0.7 mmol of FeCl3, and 0.7 mmol of 2-aminoterephthalic acid as reaction raw materials, stir for 15 min, add 10 mL of acetic acid as the solvent, perform hydrothermal reaction at 120 °C for 4 h, centrifuge and wash, and dry at 70 °C to obtain Fe-MIL-88NH2;

[0055] (2) Using 50 mg of Fe-MIL-NH2 and 10 mL of absolute ethanol as reaction raw materials, ultrasonically disperse for 3 min to obtain solution A;

[0056] (3) Using 0.2 mol of (NH4)2MoO4, 10 mL of absolute ethanol, and 40 mL of deionized water as reaction raw materials, ultrasonically disperse for 3 min to obtain solution B;

[0057] (4) Rapidly pour solution A in step (2) into solution B in step (3) during stirring in a water bath at 85 °C, stir for 10 min, centrifuge and wash, dry at 70 °C, and calcine at 450 °C in an air atmosphere for 4 h to synthesize Fe-MIL-88NH2-0.2Mo.

[0058] Example 4

[0059] (1) Using 15 mL of DMF, 0.7 mmol of FeCl3, and 0.7 mmol of 2-aminoterephthalic acid as reaction raw materials, stir for 15 min, add 10 mL of acetic acid as the solvent, perform hydrothermal reaction at 120 °C for 4 h, centrifuge and wash, and dry at 70 °C to obtain Fe-MIL-88NH2;

[0060] (2) Using 50 mg of Fe-MIL-NH2 and 10 mL of absolute ethanol as reaction raw materials, ultrasonically disperse for 3 min to obtain solution A;

[0061] (3) Using 0.31 mol of (NH4)2MoO4, 10 mL of absolute ethanol, and 40 mL of deionized water as reaction raw materials, ultrasonically disperse for 3 min to obtain solution B;

[0062] (4) Rapidly pour solution A in step (2) into solution B in step (3) during stirring in a water bath at 85 °C, stir for 10 min, centrifuge and wash, dry at 70 °C, and calcine at 450 °C in an air atmosphere for 4 h to synthesize Fe-MIL-88NH2-0.31Mo.

[0063] Application Example

[0064] For the performance analysis of the purple moon-shaped iron oxide prepared in Example 1, take the purple moon-shaped iron oxide prepared in this example, and grind it evenly with super conductive carbon black (conductive agent) and polyvinylidene fluoride (binder) in a ratio of 8:1:1. Drop 1-methyl-2-pyrrolidone to make it a uniform mixture, and then coat it on hydrophilic carbon paper. After drying, use it as the positive electrode, a zinc sheet as the negative electrode, and 2M ZnSO4 as the electrolyte to assemble a button battery.

[0065] Perform electrochemical energy storage performance tests in the potential window of 0.4 - 1.8V to obtain the cyclic voltammetry test curves of this zinc-ion battery at different scan rates. The material has a consistent shape of oxidation-reduction peaks from 1 - 8mV s -1 indicating its reversible oxidation-reduction characteristics; Figure 4 is the charge-discharge performance test curve of the assembled button battery at different current densities. From the current density of 0.2A g -1 to 20A g -1 , its maximum capacitance performance is 221mA h g -1 . The cycle performance of the zinc-ion battery with the prepared purple moon-shaped iron oxide is as Figure 5 shown. After continuous operation for 2000 cycles, the battery performance still remains 94%. In addition, the performance of Comparative Example 1 and Examples 2 - 4 are 134, 186, 163, and 142mAh g -1 . The zinc-ion battery assembled with the purple moon-shaped iron oxide prepared by the method of the present invention has excellent battery cycle stability.

Claims

1. A preparation method of doped purple string-of-pearls-shaped iron oxide, characterized in that, The preparation method comprises the following steps: (1) Using DMF, an iron source, and 2-aminoterephthalic acid as reaction raw materials, acetic acid as a solvent, and performing a hydrothermal reaction to obtain Fe-MIL-88NH2; (2) Using Fe-MIL-NH2 and absolute ethanol as reaction raw materials, performing ultrasonic dispersion to obtain solution A; (3) Using (NH4)2MoO4, absolute ethanol, and deionized water as reaction raw materials, performing ultrasonic dispersion to obtain solution B; (4) Pouring solution A in step (2) into solution B in step (3) during water bath stirring, stirring, and performing high-temperature calcination in an air atmosphere to synthesize doped purple moon-shaped iron oxide, denoted as Fe-MIL-88NH2-Mo.

2. The preparation method of the doped purple string-of-pearls-shaped iron oxide according to claim 1, wherein In step (1), the volume of the DMF is 1 mL to 30 mL, the molar mass of the iron source is 0.1 to 2 mmol, the molar mass of 2-aminoterephthalic acid is 0.1 to 2 mmol, and the acetic acid is 1 to 10 mL.

3. The preparation method of the doped purple string-of-pearls-shaped iron oxide according to claim 1, wherein, The iron source is selected from one or more of ferric chloride, ferric nitrate, ferric sulfate, or potassium ferricyanide.

4. The preparation method of Fe-MIL-88NH2-Mo according to claim 1, characterized in that, In step (1), the hydrothermal reaction temperature is 100 to 140 °C, and the hydrothermal reaction time is 2 to 6 hours.

5. The preparation method of the doped purple string-of-pearls-shaped iron oxide according to claim 1, wherein, In step (2), the mass of the Fe-MIL-88NH2 is 30 to 70 mg, the volume of the absolute ethanol is 1 to 20 mL; the ultrasonic dispersion time is 1 to 10 minutes.

6. The preparation method of the doped string-of-pearls-shaped iron oxide according to claim 1, wherein, In step (3), the molar mass of (NH4)2MoO4 is 0.1 to 0.36 mol, the volume of the deionized water is 20 to 60 mL; the ultrasonic dispersion time is 1 to 10 minutes.

7. The preparation method of the doped string-of-pearls-shaped iron oxide according to claim 1, wherein In step (4), the water bath stirring temperature is 60 to 100 °C, the stirring time is 1 to 20 min; the high-temperature calcination temperature is 400 to 500 °C, and the high-temperature calcination time is 1 to 7 hours.

8. The doped purple moon-shaped iron oxide Fe-MIL-88NH2-Mo obtained by the preparation method according to any one of claims 1 to 7.

9. The doped string-of-pearls-shaped iron oxide according to claim 8, wherein, The molar mass content of the Mo element in the Fe-MIL-88NH2-Mo > 0.1%; the morphology of the Fe-MIL-88NH2-Mo is purple moon-shaped.

10. The application of the Fe-MIL-88NH2-Mo according to claim 8 in the preparation of a zinc ion battery.

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