Preparation method and application of metal zinc negative electrode modified with material containing rich oxygen sites

Abstract

The present invention relates to the technical field of negative electrode materials for aqueous zinc ion batteries, and discloses a preparation method and application of a metal zinc negative electrode modified with a material containing rich oxygen sites. The method comprises: using ferric chloride, nitrilotriacetic acid, isopropyl alcohol, and deionized water as raw materials to perform a solvothermal reaction to generate a metal chelate nitrilotriacetate iron; then, nitrilotriacetate iron powder and a binder are mixed in N-methylpyrrolidone to form a uniform slurry, and preparing a nitrilotriacetate iron composite material having an artificial protective coating containing rich oxygen sites on the surface of a zinc foil. The artificial protective coating constructed by the present invention exhibits a dense nanorod-like structure, which can achieve uniform distribution and nucleation growth of zinc ions. The resulting composite metal zinc electrode has excellent cycle performance as a negative electrode material for aqueous zinc ion batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of negative electrode materials for aqueous zinc ion batteries, and in particular to a preparation method and application of a metal zinc negative electrode modified with a material rich in oxygen sites. Background Art

[0002] With the rapid development of society and the economy, many emerging industries, including new energy vehicles and smart wearables, rely on energy supplies, making today's energy demand issue increasingly urgent. While lithium-ion batteries are playing an increasingly important role in energy conversion, their high cost and safety concerns limit their application in areas such as electric vehicles. Therefore, there is an urgent need to find new secondary energy storage devices that can replace lithium-ion batteries in a green, safe, efficient, and low-cost manner.

[0003] Aqueous zinc-ion batteries have become popular in recent years due to the high ionic conductivity of aqueous electrolytes, which is two orders of magnitude higher than that of organic electrolytes. They are also non-flammable, safe, non-toxic, low-cost, and easy to prepare. Furthermore, the metallic zinc negative electrode has a low standard electrode potential (-0.763V) and a high hydrogen evolution overpotential (approximately 1.2V). Compared to other metal negative electrodes, it is safer and more stable in aqueous electrolytes. The metallic zinc negative electrode also has a high theoretical capacity (820mAh g -1 ), abundant resources, low price, low toxicity, and high conductivity. However, in actual application, the dendrite growth and interfacial side reactions of the metal zinc anode during the cycle greatly limit the cycle life and stability of aqueous zinc-ion batteries.

[0004] Therefore, the research on the modification of metallic zinc negative electrode of aqueous zinc ion batteries is of great significance. Summary of the Invention

[0005] In response to the problems in the background technology, the present invention provides a method for preparing a metal zinc negative electrode modified with a material rich in oxygen sites, and the zinc negative electrode has a long cycle life when used in a battery.

[0006] The first aspect of the present invention provides a method for preparing a metal zinc negative electrode modified with a material rich in oxygen sites, comprising the following steps:

[0007] 1) mixing ferric chloride, deionized water, and isopropyl alcohol in a mass ratio of 0.2-0.4:1:0.5-1 and stirring to obtain a mixed solution A;

[0008] 2) adding nitrilotriacetic acid to the mixed solution A obtained in step 1) and stirring to obtain a mixed solution B;

[0009] 3) transferring the transparent solution B obtained in step 2) to a reactor for solvothermal reaction at 180-200° C., and after completion of the reaction, removing the product, washing it, and drying it to obtain a white powder of nitrilotriacetic acid iron based on a central ion trivalent iron ion and a ligand of nitrilotriacetic acid;

[0010] 4) After grinding the ferric nitrilotriacetate to a uniform powder particle size, a binder and N-methylpyrrolidone are added in proportion and stirred to form a uniform slurry. The slurry is then coated on the surface of the zinc foil to form a protective coating of uniform thickness, thereby obtaining a metal zinc negative electrode modified with a material rich in oxygen sites.

[0011] The present invention utilizes a metal chelate formed from nitrilotriacetic acid and anhydrous ferric chloride, mixed with polyvinylidene fluoride, and then applied by blade coating to produce a uniform artificial protective coating with oxygen-containing sites on a metal zinc anode. This artificial protective layer provides stable protection for the metal zinc anode.

[0012] Nitrilotriacetic acid has three oxygen-containing functional groups and four coordination bonds, and can form a stable metal chelate with trivalent iron ions. At the same time, nitrilotriacetic acid iron and polyvinylidene fluoride form a uniform multifunctional artificial interface protective coating (non-conductive) containing abundant oxygen sites on the surface of the metal zinc negative electrode. This multifunctional insulating protective layer has regular channels, which serve as ion pathways and adsorption, helping to avoid localized concentrated zinc ion distribution. The abundant oxygen sites then induce uniform nucleation and deposition of metal zinc. The electrode material obtained by the present invention has a long cycle life when used as a negative electrode material for aqueous zinc ion batteries.

[0013] Preferably, in step 1), the stirring time is 10-25 minutes.

[0014] Preferably, in step 2), the mass ratio of nitrilotriacetic acid to deionized water is 1-1.3:1.

[0015] Preferably, in step 2), the stirring time is 5-20 minutes.

[0016] Preferably, in step 3), the solvent thermal reaction time is 18-27 hours.

[0017] Preferably, in step 3), the product nitrilotriacetic acid iron is a nanorod-like structure.

[0018] Preferably, in step 4), the protective layer is a composite phase of ferrous nitrilotriacetate containing abundant oxygen sites and a binder.

[0019] Preferably, in step 4), the binder includes one or more of polyvinylidene fluoride, styrene-butadiene rubber and hydroxymethyl cellulose.

[0020] Preferably, in step 4), the mass ratio of nitrilotriacetic acid iron powder: binder: N-methylpyrrolidone is 1:0.1-0.3:1-10.

[0021] Preferably, in step 4), the slurry is stirred for 2-4 hours.

[0022] Preferably, in step 4), the thickness of the protective layer is 50-250 microns.

[0023] The second aspect of the present invention provides a metal zinc negative electrode modified with a material rich in oxygen sites, which is prepared according to any of the methods described above.

[0024] The third aspect of the present invention provides an application of a metal zinc negative electrode modified with a material rich in oxygen sites in an aqueous zinc ion battery.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] (1) The present invention adopts a simple solvent thermal method to prepare nitrilotriacetic acid iron powder material and a scraping method to prepare an artificial protective coating with rich oxygen sites for protecting the metal zinc negative electrode. The method is simple, effective and low-cost.

[0027] (2) The metal zinc negative electrode modified with a material rich in oxygen sites prepared by the present invention is used as a negative electrode material for aqueous zinc ion batteries, which is beneficial for avoiding localized concentrated zinc ion distribution, redispersing zinc ions on the electrode surface, and inducing uniform zinc deposition. The electrode material obtained by the present invention has a long cycle life when used as a negative electrode material for aqueous zinc ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is the X-ray diffraction (XRD) pattern of the prepared nitrilotriacetic acid iron composite material;

[0029] Figure 2 (a) is a scanning electron microscope (SEM) image of pure zinc foil, (b) is an SEM image of pure zinc foil after 50 cycles, and (c) is an SEM image of the nitrilotriacetic acid iron and polyvinylidene fluoride composite electrode material after 50 cycles;

[0030] Figure 3 (a) and (b) are SEM images of the prepared nitrilotriacetic acid iron powder at different magnifications;

[0031] Figure 4 (a) and (b) are SEM images of the prepared ferric nitrilotriacetate and polyvinylidene fluoride composite materials at different magnifications;

[0032] Figure 5This is the battery cycle performance of the pure zinc foil electrode material in Comparative Example 1.

[0033] Figure 6 The battery cycle performance of the nitrilotriacetic acid iron and polyvinylidene fluoride composite electrode material prepared in Example 1;

[0034] Figure 7 This is the battery cycle performance of the nitrilotriacetic acid iron and polyvinylidene fluoride composite electrode material prepared in Example 2. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, and the present invention is not limited to the following examples. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other in the absence of conflict.

[0036] Comparative Example 1

[0037] (1) Cut the pure zinc foil electrode material with a thickness of 0.05 mm into electrode discs with a diameter of 1.2 cm. Figure 2 (a) is the scanning electron microscope (SEM) image of pure zinc foil, and (b) is the SEM image of pure zinc foil after 50 cycles. Figure 5 A symmetrical cell composed of pure zinc foil electrodes and 2 mol / L ZnSO4 electrolyte was assembled at a current density of 3 mA cm -2 , with an area capacity of 1 mAh cm -2 The time-voltage performance diagram below is shown in Table 1 for specific data.

[0038] Example 1

[0039] (1) Add 0.03394 g of black anhydrous ferric chloride to a mixed solution of 30 ml of deionized water and 30 ml of isopropanol, and stir at room temperature for 15 minutes to obtain a brown-yellow transparent mixed solution A;

[0040] (2) Slowly adding 1.2 g of nitrilotriacetic acid white powder to the mixed solution A obtained in step (1) and stirring at room temperature for 10 minutes to obtain a mixed solution B, which is yellow;

[0041] (3) The mixed solution B obtained in step (2) was transferred to a reactor for solvent thermal reaction and reacted at 180 degrees Celsius for 24 hours. After the reaction, the solution was transparent and a white precipitate was at the bottom. The solution was then washed three times with deionized water and ethanol and dried in a vacuum oven at 60 degrees Celsius for 12 hours to obtain a white powder of nitrilotriacetic acid iron based on the central ion trivalent iron ion ligand.

[0042] (4) Weigh 100 mg of white powder of nitrilotriacetic acid iron and 20 mg of polyvinylidene fluoride, pour the nitrilotriacetic acid iron into a mortar, grind for 5-10 minutes until the powder particles are uniform in size, add the weighed binder, add 0.5 ml of N-methylpyrrolidone and stir for 3 hours to form a uniform slurry, use a spatula to apply the slurry on the surface of zinc foil to form a uniform protective layer with a thickness of 100 μm, and dry it in a vacuum oven at 60 degrees Celsius for 6 hours to obtain a metal zinc negative electrode modified with a material rich in oxygen sites.

[0043] The material was then cut into electrode discs with a diameter of 1.2 cm and assembled into a symmetrical battery to test its time-voltage performance graph.

[0044] Figure 1 This is the XRD pattern of the metal chelate nitrilotriacetate iron composite material prepared in Example 1. The characteristic peaks appearing at 12.1°, 13.4°, 16.6°, 21.8° and 34.4° prove that the nitrilotriacetate iron material was successfully synthesized.

[0045] Figure 2 (c) is the SEM image of the nitrilotriacetic acid iron and polyvinylidene fluoride composite electrode material after 50 cycles. Figure 2 As can be seen from (a), (b), and (c), the surface of the metal zinc negative electrode modified with oxygen sites is relatively flat after cycling, which effectively guides the uniform deposition of zinc ions.

[0046] Figure 3 (a) and (b) are SEM images of nitrilotriacetic acid iron powder at different magnifications, and the nitrilotriacetic acid iron powder exhibits a nanorod-like structure.

[0047] Figure 4 (a) and (b) are SEM images of the composite electrode material of nitrilotriacetate iron and polyvinylidene fluoride at different magnifications. Under the good bonding effect of polyvinylidene fluoride, nitrilotriacetate iron can achieve stable and dense coating of nitrilotriacetate iron on the electrode surface.

[0048] Figure 6The figure shows the cycling performance of the symmetrical zinc battery with a 100 μm protective layer in Example 1. The electrode material is cut into electrode discs with a diameter of 1.2 cm, and the electrolyte is 2 mol / L ZnSO4. The symmetrical battery is assembled at a current density of 3 mA cm -2 , with an area capacity of 1 mAh cm -2 The time-voltage performance graph below shows that the symmetrical battery exhibits excellent electrochemical performance, with the polarization voltage remaining around 0.1 V after 550 hours of cycling. Specific data are shown in Table 1.

[0049] Example 2

[0050] (1) 0.03394 g of anhydrous ferric chloride was added to a mixed solution of 30 ml of deionized water and 30 ml of isopropyl alcohol, and stirred at room temperature for 15 minutes to obtain a mixed solution A, which was brownish yellow;

[0051] (2) Slowly adding 1.2 g of nitrilotriacetic acid to the mixed solution A obtained in step (1) and stirring at room temperature for 10 minutes to obtain a mixed solution B, which is yellow;

[0052] (3) The mixed solution B obtained in step (2) was transferred to a reactor for solvent thermal reaction and reacted at 180 degrees Celsius for 24 hours. After the reaction, the solution was transparent and a white precipitate was at the bottom. The solution was then washed three times with deionized water and ethanol and dried in a vacuum oven at 60 degrees Celsius for 12 hours to obtain a white powder of nitrilotriacetic acid iron based on the central ion trivalent iron ion ligand.

[0053] (4) Pour 100 mg of nitrilotriacetic acid iron white powder and 20 mg of polyvinylidene fluoride into a mortar and grind for 5-10 minutes until the powder particles are uniform in size, then add a weighed binder, add 0.5 ml of N-methylpyrrolidone and stir for 3 hours to form a uniform slurry, use a spatula to apply the slurry on the surface of the zinc foil to form a uniform protective layer with a thickness of 150 microns, and dry it in a vacuum oven at 60 degrees Celsius for 6 hours to obtain a metal zinc negative electrode modified with a material rich in oxygen sites.

[0054] The material was then cut into electrode discs with a diameter of 1.2 cm and assembled into a symmetrical battery to test its time-voltage performance graph.

[0055] Figure 7 The electrode material with a coating of 150 μm was cut into electrode discs with a diameter of 1.2 cm. The electrolyte was 2 mol / L ZnSO4 and a symmetrical cell was assembled at a current density of 3 mA cm -2 , with an area capacity of 1 mAh cm -2 The time-voltage performance diagram is shown in Table 1.

[0056] Example 3

[0057] (1) 0.03394 g of anhydrous ferric chloride was added to a mixed solution of 30 ml of deionized water and 30 ml of isopropyl alcohol, and stirred at room temperature for 15 minutes to obtain a mixed solution A, which was brownish yellow;

[0058] (2) Slowly adding 1.2 g of nitrilotriacetic acid to the mixed solution A obtained in step (1) and stirring at room temperature for 10 minutes to obtain a mixed solution B, which is yellow;

[0059] (3) The mixed solution B obtained in step (2) was transferred to a reactor for solvent thermal reaction and reacted at 180 degrees Celsius for 24 hours. After the reaction, the solution was transparent and a white precipitate was at the bottom. The solution was then washed three times with deionized water and ethanol and dried in a vacuum oven at 60 degrees Celsius for 12 hours to obtain a white powder of nitrilotriacetic acid iron based on the central ion trivalent iron ion ligand.

[0060] (4) Pour 96 mg of nitrilotriacetic acid iron white powder and 24 mg of polyvinylidene fluoride into a mortar and grind for 5-10 minutes until the powder particles are uniform in size, then add a weighed binder, add 0.5 ml of N-methylpyrrolidone and stir for 3 hours to form a uniform slurry, use a spatula to coat the slurry on the surface of the zinc foil to form a uniform protective layer with a thickness of 100 microns, and dry it in a vacuum oven at 60 degrees Celsius for 6 hours to obtain a metal zinc negative electrode modified with a material rich in oxygen sites.

[0061] The material was then cut into electrode discs with a diameter of 1.2 cm, and assembled into a symmetrical battery in the same manner as in Example 1. The time-voltage performance diagram was tested under the same conditions.

[0062] Example 4

[0063] (1) 0.03394 g of anhydrous ferric chloride was added to a mixed solution of 30 ml of deionized water and 30 ml of isopropyl alcohol, and stirred at room temperature for 15 minutes to obtain a mixed solution A, which was brownish yellow;

[0064] (2) Slowly adding 1.2 g of nitrilotriacetic acid to the mixed solution A obtained in step (1) and stirring at room temperature for 10 minutes to obtain a mixed solution B, which is yellow;

[0065] (3) The mixed solution B obtained in step (2) was transferred to a reactor for solvent thermal reaction and reacted at 180 degrees Celsius for 24 hours. After the reaction, the solution was transparent and a white precipitate was at the bottom. The solution was then washed three times with deionized water and ethanol and dried in a vacuum oven at 60 degrees Celsius for 12 hours to obtain a white powder of nitrilotriacetic acid iron based on the central ion trivalent iron ion ligand.

[0066] (4) Pour 92 mg of nitrilotriacetic acid iron white powder and 28 mg of polyvinylidene fluoride into a mortar and grind for 5-10 minutes until the powder particles are uniform in size, then add a weighed binder, add 0.5 ml of N-methylpyrrolidone and stir for 3 hours to form a uniform slurry. Use a spatula to apply the slurry on the surface of the zinc foil to form a uniform protective layer with a thickness of 100 microns. Dry it in a vacuum oven at 60 degrees Celsius for 6 hours to obtain a metal zinc negative electrode modified with a material rich in oxygen sites.

[0067] The material was then cut into electrode discs with a diameter of 1.2 cm, and assembled into a symmetrical battery in the same manner as in Example 1. The time-voltage performance diagram was tested under the same conditions.

[0068] The composite material of ferric nitrilotriacetate containing an artificial protective coating rich in oxygen sites for protecting the metallic zinc negative electrode in Comparative Example 1 and Examples 1-4 and pure zinc foil as aqueous zinc ion electrode materials were assembled into a zinc symmetric battery. The polarization voltage and cycle time at the same current density and areal capacity are shown in Table 1:

[0069] Table 1

[0070] Polarization voltage (v) Maximum cycle time (h) Comparative Example 1 0.2 65 Example 1 0.1 550 Example 2 0.15 90 Example 3 0.15 200 Example 4 0.18 150

[0071] As can be seen from Table 1, the aqueous zinc-ion battery exhibits different electrochemical properties as the coating thickness and raw material ratio of the nitrilotriacetic acid iron and polyvinylidene fluoride composite material are changed. When the test conditions are constant, reducing the coating thickness leads to an overall improvement in the performance of the electrode material. Comparison of Examples 1-4 with Comparative Example 1 reveals that the coating material indeed protects the metallic zinc negative electrode, extending its service life. In particular, the symmetrical cell in Example 1 exhibits excellent electrochemical performance, with the polarization voltage remaining around 0.1V after 550 hours of cycling, demonstrating excellent cycling performance.

[0072] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a metal zinc negative electrode modified with a material rich in oxygen sites, characterized in that: The following steps are involved: 1) mixing ferric chloride, deionized water, and isopropyl alcohol in a mass ratio of 0.2-0.4:1:0.5-1 and stirring to obtain a mixed solution A; 2) adding nitrilotriacetic acid to the mixed solution A obtained in step 1) and stirring to obtain a mixed solution B; 3) transferring the transparent solution B obtained in step 2) to a reactor for a solvothermal reaction at 180-200° C., removing the product after the reaction, washing it, and drying it to obtain a product nitrilotriacetic acid-containing ferric ion as a central ion and a nitrilotriacetic acid ligand, wherein the product nitrilotriacetic acid-containing ferric ion has a nanorod-like structure; 4) After the ferrous nitrilotriacetate is ground into a powder with uniform particle size, a binder and N-methylpyrrolidone are added in proportion and stirred to form a uniform slurry. The slurry is then coated on the surface of the zinc foil to form a protective coating with uniform thickness. The protective coating is a composite phase of the ferrous nitrilotriacetate containing rich oxygen sites and the binder. After drying, a metal zinc negative electrode modified with a material containing rich oxygen sites is obtained.

2. The method for preparing a metal zinc negative electrode modified with a material rich in oxygen sites according to claim 1, characterized in that: In the step 1), the stirring time is 10-25 minutes.

3. The method for preparing a metal zinc negative electrode modified with a material containing rich oxygen sites according to claim 1, characterized in that: In the step 2), the mass ratio of nitrilotriacetic acid to deionized water is 1-1.3:1, and / or the stirring time is 5-20 minutes.

4. The method for preparing a metal zinc negative electrode modified with a material rich in oxygen sites according to claim 1, characterized in that: In the step 3), the solvent thermal reaction time is 18-27 hours.

5. The method for preparing a metal zinc negative electrode modified with a material containing rich oxygen sites according to claim 1, characterized in that: In the step 4), the binder comprises one or more of polyvinylidene fluoride, styrene-butadiene rubber and hydroxymethyl cellulose, and / or the mass ratio of nitrilotriacetic acid iron powder: binder: N-methylpyrrolidone is 1:0.1-0.3:1-10.

6. The method for preparing a metal zinc negative electrode modified with a material containing rich oxygen sites according to claim 1, characterized in that: In step 4), the slurry is stirred for 2-4 hours, and / or dried in a vacuum oven at 50-80 degrees Celsius for 4-8 hours.

7. The method for preparing a metal zinc negative electrode modified with a material containing rich oxygen sites according to claim 1, characterized in that: In the step 4), the thickness of the protective layer is 50-250 microns.

8. A metal zinc negative electrode modified with a material rich in oxygen sites, characterized in that: Prepared according to any one of claims 1 to 7.

9. Use of a metal zinc negative electrode modified with a material rich in oxygen sites according to claim 8 in an aqueous zinc ion battery.

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