Preparation method of composite interface layer modified zinc negative electrode

Abstract

The invention provides a preparation method of a composite interface layer modified zinc negative electrode, which comprises the following steps: grinding commercial zinc foil, preparing an acetic acid solution of chitosan, adding pectin to obtain a composite solution, cleaning an electro-deposition tank, connecting a working electrode to standby zinc foil, connecting a reference electrode to a saturated calomel electrode, connecting a counter electrode to a platinum electrode, and carrying out electrodeposition to obtain the composite interface layer modified zinc negative electrode. And pouring the composite solution into an electro-deposition tank, completely immersing an electrode in the composite solution, carrying out electro-deposition, depositing a C-coated Zn material film on a standby zinc foil, and washing and drying to obtain the composite interface layer modified zinc negative electrode. The zinc negative electrode material with the chitosan modified layer is obtained through an electrochemical deposition method, the process is simple, the process is easy to control, the preparation time is short, high single yield can be achieved, and large-scale production is facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of zinc electrodes, and in particular relates to a method for preparing a composite interface layer modified zinc negative electrode. Background Art

[0002] Rechargeable zinc-ion batteries have attracted much attention due to their high specific capacity, low redox potential, low price, and environmental friendliness. They have great potential and become a strong competitor in future energy storage technologies. In particular, the unique properties of zinc metal as a charge carrier - its "host-free" characteristics can maximize the anode capacity and operating voltage. However, zinc-ion batteries face some challenges on the road to widespread commercialization. Side reactions triggered by water and oxygen and the uneven deposition of zinc ions on the negative electrode are the main difficulties that currently hinder their large-scale application. These problems not only affect the stability of battery performance, but also limit the practical application of zinc-ion batteries. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method for preparing a composite interface layer modified zinc negative electrode in view of the deficiencies of the above-mentioned prior art. The method solves the two technical problems of zinc dendrites and side reactions in the field of zinc ion batteries, and realizes a zinc negative electrode material with a chitosan modified layer through an electrochemical deposition method. The process is simple, the process is easy to control, the preparation time is short, a higher single output can be achieved, and it is conducive to large-scale production.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a composite interface layer modified zinc negative electrode, the method comprising:

[0005] S1, polish the commercial zinc foil with sandpaper to remove the passivation layer, then ultrasonically clean it with deionized water and ethanol in sequence, and after drying, obtain a spare zinc foil;

[0006] S2, adding chitosan powder into 2% acetic acid solution, stirring and dissolving, to obtain chitosan acetic acid solution;

[0007] S3, adding pectin to the acetic acid solution of chitosan obtained in S2, stirring and dissolving to obtain a composite solution;

[0008] S4, clean the electrodeposition tank, connect the working electrode to the spare zinc foil obtained in S1, connect the reference electrode to the saturated calomel electrode, and connect the counter electrode to the platinum electrode;

[0009] S5. Pour the composite solution obtained in S3 into an electrodeposition tank, completely immerse the electrode in the composite solution, perform electrodeposition, deposit a C@Zn material film on the spare zinc foil, wash with deionized water, and dry to obtain a composite interface layer modified zinc negative electrode.

[0010] Preferably, the ultrasonic cleaning time in S1 is 30 minutes, the drying temperature is 60° C. to 80° C., and the drying time is 10 minutes to 40 minutes.

[0011] Preferably, the concentration of the chitosan acetic acid solution in S2 is 0.5 mol / L to 2 mol / L, and the stirring and dissolving time is 2 h to 3 h.

[0012] Preferably, the usage ratio of the acetic acid solution of pectin and chitosan in S3 is (0.2-1) g: (10-50) mL, and the stirring and dissolving time is 4 h to 6 h.

[0013] Preferably, the electrodeposition voltage in S5 is 1V to 20V, the current is 1mA to 10mA, the temperature is room temperature, and the time is 20min to 60min.

[0014] Preferably, the deionized water washing times in S5 are 3 times, the drying temperature is 50° C. to 80° C., and the drying time is 4 h to 7 h.

[0015] Preferably, the thickness of the C@Zn material film in S5 is 30 μm to 50 μm.

[0016] Preferably, the multifunctional composite interface layer modified zinc negative electrode is -1 , capacity is 2mA·hg -1 The assembled symmetrical battery has a cycle life of more than 500h.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. The present invention constructs a stable composite interface layer on the zinc negative electrode, utilizes the organic functional groups (amino, carbonyl, etc.) of the composite material to regulate the deposition process of zinc ions, promotes the uniform migration of zinc ions on the electrode surface, and forms a uniform coating, thereby greatly improving the reversibility and stability of zinc in the dissolution / deposition process.

[0019] 2. The present invention improves the interface characteristics between the zinc negative electrode and the electrolyte, and enhances the performance of the zinc ion battery through electrodeposition, so that the product has higher coulombic efficiency and longer cycle life.

[0020] 3. The control parameters of the electrodeposition method in the present invention realize the precise control of the interface layer, and the interface layer remains stable after the battery is charged and discharged thousands of times.

[0021] 4. The present invention uses the chitosan composite protective layer as the interface layer of the zinc negative electrode. This interface layer has good mechanical stability and is not easily damaged during the continuous charge and discharge process. It can not only limit the free water molecules on the interface and inhibit the side reactions induced by water; it can also promote the Zn 2+ Migrate evenly on the electrode surface and inhibit the growth of zinc dendrites.

[0022] The present invention is further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a SEM plan view of the C@Zn material film prepared in Example 1 of the present invention.

[0024] Figure 2 This is a SEM cross-sectional view of the composite interface layer modified zinc negative electrode prepared in Example 1 of the present invention.

[0025] Figure 3 This is a linear curve diagram characterizing the corrosion performance of the composite interface layer modified zinc negative electrode prepared in Example 1 of the present invention.

[0026] Figure 4 This is the SEM image of the zinc negative electrode modified with a composite interface layer prepared in Example 1 of the present invention before cycling.

[0027] Figure 5 This is the SEM image of the zinc negative electrode modified with a composite interface layer prepared in Example 1 of the present invention after cycling.

[0028] Figure 6 The composite interface layer modified zinc negative electrode prepared in Example 1 of the present invention is subjected to a current density of 1 mA·cm -2 , with a capacity of 0.5 mAh cm -2 Comparison of the Coulombic efficiency of different zinc-titanium alloys.

[0029] Figure 7 The composite interface layer modified zinc negative electrode prepared in Example 1 of the present invention was subjected to a current density of 5 mA·cm -2 , capacity is 2 mAh cm -2 Below is a comparison chart of long cycle performance of different zinc-zinc symmetric batteries. DETAILED DESCRIPTION

[0030] Example 1

[0031] The preparation method of the composite interface layer modified zinc negative electrode of this embodiment is as follows:

[0032] S1. Grind a 5 cm × 5 cm commercial zinc foil with sandpaper to remove the passivation layer, then ultrasonically clean it with deionized water and ethanol for 30 min, and dry it at 60° C. for 40 min to obtain a spare zinc foil;

[0033] S2, adding chitosan powder to acetic acid solution with a mass fraction of 2%, stirring and dissolving for 2 hours to obtain an acetic acid solution of chitosan with a concentration of 2 mol / L;

[0034] S3, adding 0.2 g pectin to the acetic acid solution of chitosan obtained in 10 mL S2, stirring and dissolving for 4 h to obtain a composite solution;

[0035] S4, clean the electrodeposition tank, connect the working electrode to the spare zinc foil obtained in S1, connect the reference electrode to the saturated calomel electrode, and connect the counter electrode to the platinum electrode;

[0036] S5. Pour the composite solution obtained in S3 into an electrodeposition tank, completely immerse the electrode in the composite solution, and perform electrodeposition at a voltage of 1 V, a current of 10 mA, a temperature of room temperature, and a time of 20 min. Deposit a 30 μm thick C@Zn material film on the spare zinc foil, wash it with deionized water three times, and dry it at 50°C for 7 hours to obtain a composite interface layer modified zinc negative electrode (C@Zn electrode).

[0037] Figure 1 The SEM plane image of the prepared composite material. After the electrodeposition reaction is completed, the surface of the zinc foil is covered with a thin film. Through the scanning electron microscope, it can be observed that the surface of the film is dense and smooth, and it evenly covers the zinc electrode.

[0038] Unlike the scraping method, the scraping method is easy to squeeze the gas into the coating due to the shear force of the scraper on the coating, which easily generates bubbles when preparing the film, resulting in loose and uneven films. In addition, the scraping method requires manual operation, so it is not suitable for large-scale and high-frequency material production.

[0039] Figure 2 This is a SEM cross-sectional image of the prepared C@Zn material. The film is evenly attached to the surface of zinc metal. Thanks to the advantages of mild electrodeposition conditions and easy control, the thickness of the electrodeposited composite film is controlled at 30μm.

[0040] In addition, the present invention has the following advantages: (1) relatively low cost: the electrodeposition process is simple, easy to operate, and environmentally friendly, and the production method is flexible and suitable for large-scale industrial production; (2) improving the interface bonding between the film and the substrate: electrodeposition can achieve good bonding between the coating material and the substrate, which is beneficial for improving the adhesion and durability of the film; (3) strong controllability: by controlling the process conditions (such as deposition voltage, current, solution pH, temperature, concentration, deposition time, etc.), the thickness, chemical composition and structure of the deposited layer can be precisely controlled.

[0041] Figure 3The figure is a linear curve that characterizes the corrosion performance. The inhibitory effect of chitosan coating on zinc corrosion reaction was analyzed by linear polarization experiment. Compared with pure zinc electrode, the corrosion potential of C@Zn is significantly positively shifted, indicating that it is less prone to corrosion reaction. In addition, it can be observed that the corrosion current of C@Zn is lower, indicating that the interface layer can reduce the corrosion reaction rate.

[0042] Figure 4 This is the SEM image of the prepared electrode material before cycling. Figure 5 The SEM image of the prepared electrode material after cycling. By observing the surface morphology of the electrode before and after cycling, it was found that after multiple cycles, the surface of the pure zinc electrode was extremely uneven, with a large number of zinc dendrites, and the surface had been severely damaged.

[0043] In contrast, the surface of the C@Zn electrode is flat, and the morphology changes only slightly after cycling, and no obvious zinc dendrite growth is observed.

[0044] Figure 6 At a current density of 1 mA·cm -2 , with a capacity of 0.5 mAh cm -2 Comparison of coulombic efficiency of different zinc-titanium batteries. Coulombic efficiency can evaluate the reversibility of zinc plating / stripping behavior on the zinc electrode. Figure 6 As shown, when the current density is 1 mA cm -2 Capacity: 0.5 mAh cm -2 The zinc-titanium half-cell exhibited a very stable Coulombic efficiency value within 300 hours, with an average value of 99.05%, demonstrating good cycle reversibility.

[0045] Figure 7 At a current density of 5 mA cm -2 , capacity is 2 mAh cm -2 The following is a comparison of the long cycle of different zinc-zinc symmetric batteries. The symmetric battery assembled with pure zinc can no longer operate after about 200 hours, while the symmetric battery assembled with zinc negative electrode modified by composite materials still shows an excellent service life of more than 500 hours.

[0046] The improved zinc-ion battery products can be tested and verified in different energy storage devices, such as flexible devices, portable rechargeable devices, low-power devices, etc. This can help solve the limitations of traditional lithium batteries and provide new ideas for the development of cleaner, safer and more economical battery products.

[0047] Example 2

[0048] The preparation method of the composite interface layer modified zinc negative electrode of this embodiment is as follows:

[0049] S1. Grind a 5 cm × 5 cm commercial zinc foil with sandpaper to remove the passivation layer, then ultrasonically clean it with deionized water and ethanol for 30 min, and dry it at 80° C. for 10 min to obtain a spare zinc foil;

[0050] S2, adding chitosan powder to 2% acetic acid solution by mass, stirring and dissolving for 3 hours, to obtain 0.5 mol / L chitosan acetic acid solution;

[0051] S3, adding 1 g of pectin to the acetic acid solution of chitosan obtained in 50 mL of S2, stirring and dissolving for 6 h to obtain a composite solution;

[0052] S4, clean the electrodeposition tank, connect the working electrode to the spare zinc foil obtained in S1, connect the reference electrode to the saturated calomel electrode, and connect the counter electrode to the platinum electrode;

[0053] S5. Pour the composite solution obtained in S3 into an electrodeposition tank, completely immerse the electrode in the composite solution, and perform electrodeposition at a voltage of 20 V, a current of 1 mA, a temperature of room temperature, and a time of 60 min. Deposit a 50 μm thick C@Zn material film on the spare zinc foil, wash it with deionized water three times, and dry it at 80°C for 4 hours to obtain a composite interface layer modified zinc negative electrode.

[0054] The multifunctional composite interface layer modified zinc negative electrode prepared in this example was subjected to a current density of 2 mA·g -1 , capacity is 1mA·hg -1 The Coulomb efficiency can be as high as 98.99%.

[0055] The multifunctional composite interface layer modified zinc negative electrode prepared in this example was subjected to a current density of 5 mA·g -1 , capacity is 2mA·hg -1 The cycle life of the assembled symmetrical battery can exceed 500h.

[0056] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a composite interface layer modified zinc negative electrode, characterized in that: The method is: S1, polish the commercial zinc foil with sandpaper to remove the passivation layer, then ultrasonically clean it with deionized water and ethanol in sequence, and after drying, obtain a spare zinc foil; S2, adding chitosan powder into 2% acetic acid solution, stirring and dissolving, to obtain chitosan acetic acid solution; S3, adding pectin to the acetic acid solution of chitosan obtained in S2, stirring and dissolving to obtain a composite solution; S4, clean the electrodeposition tank, connect the working electrode to the spare zinc foil obtained in S1, connect the reference electrode to the saturated calomel electrode, and connect the counter electrode to the platinum electrode; S5. Pour the composite solution obtained in S3 into an electrodeposition tank, completely immerse the electrode in the composite solution, perform electrodeposition, deposit a C@Zn material film on the spare zinc foil, wash with deionized water, and dry to obtain a composite interface layer modified zinc negative electrode.

2. The method for preparing a multifunctional composite interface layer modified zinc negative electrode according to claim 1, characterized in that: The ultrasonic cleaning time in S1 is 30 minutes, the drying temperature is 60° C. to 80° C., and the drying time is 10 minutes to 40 minutes.

3. The method for preparing a multifunctional composite interface layer modified zinc negative electrode according to claim 1, characterized in that: The concentration of the chitosan acetic acid solution in S2 is 0.5 mol / L to 2 mol / L, and the stirring and dissolving time is 2 h to 3 h.

4. The method for preparing a multifunctional composite interface layer modified zinc negative electrode according to claim 1, characterized in that: The dosage ratio of the acetic acid solution of pectin and chitosan in S3 is (0.2-1) g: (10-50) mL, and the stirring and dissolving time is 4 h to 6 h.

5. The method for preparing a multifunctional composite interface layer modified zinc negative electrode according to claim 1, characterized in that: The electrodeposition voltage in S5 is 1V to 20V, the current is 1mA to 10mA, the temperature is room temperature, and the time is 20min to 60min.

6. The method for preparing a multifunctional composite interface layer modified zinc negative electrode according to claim 1, characterized in that: The number of deionized water washing in S5 is 3 times, the drying temperature is 50° C. to 80° C., and the drying time is 4 h to 7 h.

7. The method for preparing a multifunctional composite interface layer modified zinc negative electrode according to claim 1, characterized in that: The thickness of the C@Zn material film described in S5 is 30 μm to 50 μm.

8. The method for preparing a multifunctional composite interface layer modified zinc negative electrode according to claim 1, characterized in that: The multifunctional composite interface layer modified zinc anode described in S5 was subjected to a current density of 5 mA·g -1 , capacity is 2mA·hg -1 The assembled symmetrical battery has a cycle life of more than 500h.

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