Preparation method and application of zinc anode of aqueous zinc ion battery

Abstract

The invention relates to the technical field of zinc anodes of aqueous zinc ion batteries, and discloses a preparation method and application of a zinc anode of an aqueous zinc ion battery. According to the method, the surface of the commercial zinc foil is reconstructed by using 0.5-0.02 mol / L of gluconic acid solution through simple chemical solution reaction, and the 3D (at) 101-Zn anode is prepared. According to the anode, a surface passivation layer is removed, a 3D hill-shaped structure is constructed, the advantageous crystal face of zinc deposition is adjusted, and the anode has high HER overpotential and excellent nucleation dynamic characteristics. The result shows that the cycle life of the 3D (at) 101-Zn3D (at) 101-Zn symmetric battery at 5.0 mA cm <-2 > exceeds 5000 hours, and the cycle life of the 3D (at) 101-Zn3D (at) 101-Zn symmetric battery at 10.0 mA cm <-2 > exceeds 2500 hours; the coulombic efficiency of the 3D (at) 101-ZnCu half cell under 4mA cm <-2 > (1mAh cm <-2 >) reaches 99.7%, the coulombic efficiency is excellent in Tafel, LSV and cyclic voltammetry (CV) tests, and the charge-discharge efficiency, the power density and the reversibility of the cell are improved. The invention provides a brand new strategy for the high stability of the highly reversible zinc metal anode and the construction of a 3D rapid ion diffusion surface, and is beneficial to promoting the wide application of the aqueous zinc-based battery.

Description

Technical Field

[0001] The present invention relates to the technical field of zinc anodes for aqueous zinc-ion batteries, and discloses a preparation method and application of a zinc anode for an aqueous zinc-ion battery. Background Art

[0002] Under the background of the global energy structure's sustainable transformation, electrochemical energy storage technology has become the focus of scientific research and engineering applications. Aqueous zinc-based batteries have attracted much attention due to the low cost of zinc anodes, high theoretical capacity, low redox potential, and environmental friendliness, and are expected to become a key technology for large-scale energy storage. However, there are many practical application problems with zinc anodes. On the one hand, dendrite growth can cause battery short circuits, the hydrogen evolution reaction consumes charge and generates hydrogen, and corrosion problems lead to the loss of active substances. On the other hand, the surface of commercial zinc foil has a natural passivation layer, with a rough surface and uneven electric field distribution, resulting in a tip effect. At high current densities, dendrites appear earlier, and the battery life is sharply reduced. These problems restrict the stability of zinc anodes and the battery cycle life, and hinder the commercialization of aqueous zinc-based batteries.

[0003] Although existing technologies can effectively alleviate these problems, many problems are also exposed. For example, the de-passivation strategy can remove the passivation layer on the surface of the zinc anode, but sandpaper polishing will leave scratches, increasing the risk of zinc dendrite formation. Constructing a 3D electrode can alleviate dendrite growth. For example, a 3D array zinc anode can restrict Zn 2+ deposition and accelerate Zn / Zn 2+ conversion, but dendrites are still inevitable, and the cost of some 3D electrode substrate materials is high, which is not conducive to commercialization. In terms of preferential crystal plane reconstruction, the crystal plane energy can inhibit the growth of zinc dendrites to a certain extent, but it is chemically unstable and is easily corroded by aqueous solutions, resulting in the disordered growth of zinc dendrites, reducing the Coulomb efficiency and limiting the battery life. Summary of the Invention

[0004] In order to overcome the deficiencies of the prior art, the present invention aims to provide a new preparation method for a zinc anode of an aqueous zinc-ion battery. By optimizing the preparation process and structural design, this method effectively inhibits the dendrite growth of the zinc anode, reduces the hydrogen evolution reaction and the generation of by-products, thereby improving the battery cycle life and performance. At the same time, this method should also have the characteristics of simple process, low cost, and easy large-scale production to meet the wide application requirements of aqueous zinc-ion batteries in fields such as electric vehicles, large-scale energy storage systems, national defense and military industries, consumer electronics, and power systems.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A preparation method of a zinc anode for an aqueous zinc-ion battery, comprising the following steps:

[0007] Dissolve gluconic acid in deionized water to obtain an aqueous solution of gluconic acid; wash a zinc foil with deionized water and absolute ethanol to obtain Bare Zn; drop the gluconic acid solution onto the bare Zn and react for 0.5 - 2 h, then rinse with deionized water and dry. Cut the prepared zinc foil into pieces to obtain the 3D@101-Zn anode.

[0008] Further, the thickness of the zinc foil is 0.05 - 0.3 mm, and the purity is ≥99.99%.

[0009] Further, after the reaction between the gluconic acid solution and the zinc foil, the number of rinsing times is 3 - 5 times.

[0010] Further, the concentration of the aqueous solution of gluconic acid is 0.005 - 0.02 mol / L.

[0011] Further, the zinc foil needs to be washed with deionized water and absolute ethanol before the reaction to remove surface oil stains and impurities.

[0012] Further, the gluconic acid used in the preparation process is of analytical pure (AR) grade.

[0013] Further, the reaction time is preferably 1 h to obtain the 3D@101-Zn anode with the best performance.

[0014] The present invention also discloses a 3D@101-Zn anode obtained by the above preparation method.

[0015] The present invention also discloses the application of the above 3D@101-Zn anode in a zinc-ion battery.

[0016] The beneficial effects of the present invention compared with the prior art are:

[0017] The present invention discloses a method for constructing a 3D@101-Zn anode. Treating commercial zinc foil with a gluconic acid solution can inhibit side reactions, reduce dendrite growth, construct a 3D hill-like structure on the zinc anode surface, provide a high-speed ion migration channel, improve the reversibility and stability of the battery under harsh conditions such as normal and high current densities, and solve the problems of poor stability and short cycle life caused by dendrite growth and side reactions of the zinc anode.

[0018] Furthermore, by controlling the reaction time of the gluconic acid solution, the structure and performance of the 3D@101-Zn anode can be optimized, and the cycle stability and electrochemical performance of the zinc-ion battery at different current densities can be further improved. This preparation method is simple and low-cost, providing a new strategy for constructing highly reversible zinc metal anodes and facilitating the wide application of aqueous zinc-based batteries.

[0019] The present invention also discloses the application of the 3D@101-Zn anode in zinc-ion batteries. The results show that the 3D@101-Zn||3D@101-Zn symmetric battery can cycle for more than 5000 hours at 5 mA cm -2 (1 mAh cm -2 ), and more than 2500 hours at 10 mA cm -2 (1 mAh cm -2 ); the 3D@101-Zn||Cu half-cell has a coulombic efficiency of 99.7% at 4 mA cm -2 (1 mAh cm -2 ). This is due to its 3D hill-like structure, (101) preferential deposition crystal plane, and removal of the surface passivation layer, which effectively inhibit dendrite growth and side reactions.

[0020] In Tafel, LSV, and cyclic voltammetry (CV) tests, the 3D@101-Zn anode performs excellently, with a low corrosion current, a more negative HER potential, and a low nucleation overpotential, showing significant advantages in inhibiting side reactions, regulating Zn 2+ deposition, and enhancing the electrochemistry reaction kinetics, thus improving the charge-discharge efficiency, power density, and reversibility of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the cycle life diagram of the symmetric battery prepared in Application Example 1 and Application Comparative Example 1;

[0022] Figure 2 is the cycle life diagram of the symmetric battery prepared in Application Example 2 and Application Comparative Example 2;

[0023] Figure 3 is the cycle life diagram of the zinc-copper asymmetric battery prepared in Application Example 3 and Application Comparative Example 3;

[0024] Figure 4 is the CV curve diagram prepared in Application Example 4 and Application Comparative Example 4;

[0025] Figure 5 is the LSV curve diagram prepared in Application Example 5 and Application Comparative Example 5;

[0026] Figure 6 is the Tafel curve diagram prepared in Application Example 6 and Application Comparative Example 6. DETAILED DESCRIPTION OF THE INVENTION

[0027] The present invention will be described in detail below through specific examples, but the protection scope of the present invention is not limited. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can all be obtained from commercial channels.

[0028] Example 1

[0029] Preparation method of zinc anode for aqueous zinc-ion battery

[0030] Step 1: Preparation of Bare Zn anode

[0031] The 0.1-mm-thick zinc foil is first ultrasonically treated in deionized water for 5 min and then in absolute ethanol for 10 min to remove surface oil stains and impurities. The obtained zinc foil is punched into circular pieces with a diameter of 12 mm as the Bare Zn anode.

[0032] Step 2: Preparation of 3D@101-Zn anode

[0033] Disperse 0.06 g of gluconic acid (AR) in 40 mL of deionized water (DL water) to obtain a 0.01 m aqueous solution of gluconic acid. At the same time, wash a 10×10 cm -2 zinc foil (zinc, 0.1 mm thick, ≥99.99%) with deionized water and absolute ethanol to obtain Bare Zn. Then, the gluconic acid solution is dropped on the bare Zn for different reaction times (0.5, 1, 2 h), and then rinsed 3 times with deionized water and dried, denoted as 3D@101-Zn(X) (3D@101-Zn(0.5 h), 3D@101-Zn(1.0 h), 3D@101-Zn(2.0 h) respectively). After cutting the prepared zinc foil into sheets with a diameter of 12 mm, the 3D@101-Zn(X) anode is obtained. According to the results of the half-cell performance, diffusion behavior, and cycling performance of different anodes, the 3D@101-Zn(X) anode is selected as the experimental group for further research. 3D@101-Zn refers to 3D@101-Zn(1.0 h).

[0034] Step 3: Preparation of AC cathode

[0035] Mix activated carbon, conductive carbon black, and polyvinylidene fluoride (PVDF) in a mass ratio of 7:2:1 (0.175 g:0.05 g:0.025 g), add N-methylpyrrolidone (NMP) and stir until the appropriate viscosity, and then evenly scrape and coat it on the titanium foil with a coater, and place it in a vacuum drying oven at 80 °C for 12 h. After cutting it into circular pieces with a diameter of 14 mm, the AC cathode is obtained.

[0036] Application Example 1

[0037] Using Bare Zn as the electrode material, select Whatman glass fiber membrane (Whatman, GF / A) as the separator, and 2M ZnSO 4 electrolyte, and assemble a CR2032 coin-type symmetric battery in air using a Neware battery test system (CT4008Tn, Shenzhen, China). At a current density of 5 mA cm -2, the areal capacity is 1 mAh cm -2 The cyclic stability test was carried out under the conditions.

[0038] Application Example 2

[0039] Using Bare Zn as the electrode material, a symmetric battery was assembled in the same way as in Application Example 1. At a current density of 10 mA cm -2 , the areal capacity is 1 mAh cm -2 The cyclic stability test was carried out under the conditions.

[0040] Application Example 3

[0041] A 0.01 mm thick copper foil ( ≥99.99%) was used as the cathode, and Bare Zn was used as the anode. A half-cell was assembled under the same conditions as in Application Example 1. At a current density of 4 mA cm -2 , the areal capacity is 1 mAh cm -2 The charge-discharge cycle test was carried out under the conditions.

[0042] Application Example 4

[0043] Using Bare Zn as the anode material and commercially available activated carbon (AC) as the cathode material, 2M ZnSO 4 solution was used as the electrolyte, and a battery was assembled in the same way as in Application Example 1. The rate performance test was carried out in the range of 0.01 A g -1 -2 A g -1 The CV scanning rate increased from 2 mV s -1 to 30 mV s -1 , and the long-cycle current density was 10 A g -1 .

[0044] Application Example 5

[0045] A three-electrode system was used. The working electrode was Bare Zn, the counter electrode was a platinum sheet electrode, and the reference electrode was Hg / HgCl 2 , and the test was carried out in 1M Na 2 SO 4 solution.

[0046] Application Example 6

[0047] A three-electrode system was used. The working electrode was selected as Bare Zn, the counter electrode was a platinum sheet electrode, and the reference electrode was Hg / HgCl 2 . The test was carried out in 2M ZnSO 4 electrolyte.

[0048] Application Comparative Example 1

[0049] Using 3D@101-Zn as the electrode material, assemble a symmetric battery in the same manner as Application Example 1. At a current density of 5 mA cm -2 , and a areal capacity of 1 mAh cm -2 , perform a cycling stability test.

[0050] Application Comparative Example 2

[0051] Using 3D@101-Zn as the electrode material, assemble a symmetric battery in the same manner as Application Example 1. At a current density of 10 mA cm -2 , and a areal capacity of 1 mAh cm -2 , perform a cycling stability test.

[0052] Application Comparative Example 3

[0053] Use a 0.01 mm thick copper foil ( ≥99.99%) as the cathode, 3D@101-Zn as the anode, and assemble a half-cell under the same conditions as Application Example 1. At a current density of 4 mA cm -2 , and a areal capacity of 1 mAh cm -2 , perform a charge-discharge cycling test.

[0054] Application Comparative Example 4

[0055] Use 3D@101-Zn as the anode material, commercially available activated carbon (AC) as the cathode material, and 2M ZnSO 4 solution as the electrolyte, and assemble a battery in the same manner as Application Example 1. Perform a rate performance test in the range of 0.01 A g -1 -2 A g -1 , and increase the CV scan rate from 2 mV s -1 to 30 mV s -1 , and the long-term cycling current density is 10 A g -1 .

[0056] Application Comparative Example 5

[0057] Adopt a three-electrode system, with the working electrode being 3D@101-Zn, the counter electrode being a platinum sheet electrode, and the reference electrode being Hg / HgCl 2 , and perform the test in 1M Na 2 SO 4 solution.

[0058] Application Comparative Example 6

[0059] Adopt a three-electrode system, select 3D@101-Zn as the working electrode, the counter electrode is a platinum sheet electrode, and the reference electrode is Hg / HgCl2. Perform the test in 2M ZnSO 4 electrolyte.

[0060] Figure 1 Under the conditions of a current density of 5 mA cm -2 and an areal capacity of 1 mAh cm -2 , the comparison of the cycle life of the Bare Zn and 3D@101-Zn symmetric cells is shown. It can be clearly observed from the figure that the 3D@101-Zn symmetric cell has excellent cycle stability, can operate stably for more than 5000 h, and the voltage curve is smooth, which can promote the orderly deposition and stripping of zinc ions, reduce dendrites and side reactions. While the Bare Zn symmetric cell short-circuited after only 190 h. This is because there are problems such as a surface passivation layer and uneven electric field distribution on the Bare Zn anode, which lead to easy dendrite growth during the deposition and stripping of zinc ions, thereby triggering cell short-circuiting and seriously affecting the cycle life of the cell. Through the Figure 1 comparison, the significant advantage of the 3D@101-Zn anode in improving the cycle stability of symmetric cells is fully demonstrated.

[0061] Figure 2 Under the conditions of a current density of 10 mA cm -2 and an areal capacity of 1 mAh cm -2 , the cycle life performance of the Bare Zn and 3D@101-Zn symmetric cells is presented. Under such harsh conditions of high current density, the 3D@101-Zn symmetric cell cycles for more than 2500 h. With its unique structure and crystal plane orientation, it provides a transport channel for zinc ions, inhibits dendrites and side reactions. While the cycle stability of the Bare Zn symmetric cell drops sharply, unable to meet the requirements of stable operation at high current for a long time. This further proves the excellent performance of the 3D@101-Zn anode in dealing with high current density working conditions.

[0062] Figure 3 The cycle life of the 3D@101-Zn||Cu zinc-copper asymmetric cell is shown, and the test conditions are 4 mA cm -2 (1 mAh cm -2 ). Under these conditions, the 3D@101-Zn||Cu half-cell achieved a remarkable Coulombic efficiency of up to 99.7%, with efficient deposition and stripping of zinc ions during charge and discharge, reduced irreversible reactions, and a long cycle life. Due to its effective regulation of zinc ion deposition to avoid dendrites, it has obvious advantages compared with traditional anodes, providing a new direction for improving the performance of zinc-based batteries.

[0063] Figure 4Cyclic voltammetry (CV) scans of Bare Zn and 3D@101-Zn. In the CV test, the battery using the 3D@101-Zn anode showed significantly different characteristics from the Bare Zn battery. As can be seen from the figure, the battery with the 3D@101-Zn anode had a lower nucleation overpotential (11 mV). This phenomenon indicates that the special structure and surface properties of the 3D@101-Zn anode can effectively promote the uniform deposition of zinc ions, reduce the possibility of non-uniform deposits formed during the zinc ion deposition process, and thus improve the reversibility of the battery. In contrast, the battery with the Bare Zn anode had a higher nucleation overpotential (17 mV), which would lead to more prone local aggregation and dendrite growth problems during the zinc ion deposition process, reducing the reversibility and cycle stability of the battery. Therefore, through the comparison of the CV scans, it fully demonstrates the important role of the 3D@101-Zn anode in improving the zinc ion deposition behavior and enhancing the battery reversibility.

[0064] Figure 5 Cyclic voltammetry (CV) scans of Bare Zn and 3D@101-Zn. In the CV test, the battery using the 3D@101-Zn anode showed significantly different characteristics from the Bare Zn battery. As can be seen from the figure, the battery with the 3D@101-Zn anode had a lower nucleation overpotential (11 mV). This phenomenon indicates that the special structure and surface properties of the 3D@101-Zn anode can effectively promote the uniform deposition of zinc ions, reduce the possibility of non-uniform deposits formed during the zinc ion deposition process, and thus improve the reversibility of the battery. In contrast, the battery with the Bare Zn anode had a higher nucleation overpotential (17 mV), which would lead to more prone local aggregation and dendrite growth problems during the zinc ion deposition process, reducing the reversibility and cycle stability of the battery. Therefore, through the comparison of the CV scans, it fully demonstrates the important role of the 3D@101-Zn anode in improving the zinc ion deposition behavior and enhancing the battery reversibility. 2 SO 4 Linear sweep voltammetry (LSV) curves of Bare Zn and 3D@101-Zn in 1M Na 2 solution. It can be clearly seen from the figure that at a current density of 10 mA / cm

[0065] Figure 6 Linear sweep voltammetry (LSV) curves of Bare Zn and 3D@101-Zn in 2M ZnSO 4 electrolyte. By analyzing the Tafel curves, key information such as the corrosion current of the electrode can be obtained. From the data in the figure, the corrosion current of the 3D@101-Zn electrode was 0.158 mA / cm 2, while the corrosion current of the Bare Zn electrode is as high as 0.501 mA / cm 2 , with good corrosion resistance. Its unique surface structure and composition remove the passivation layer, construct a 3D structure, optimize the interface, and reduce the corrosion probability. The results of the Tafel curve fully demonstrate the excellent ability of the 3D@101-Zn anode in suppressing surface corrosion, which helps to improve the stability and service life of zinc-based batteries.

[0066] The above-described embodiments are only the preferred embodiments of the present invention, rather than all the feasible embodiments of the present invention. For those of ordinary skill in the art, any obvious modifications made without departing from the principles and spirit of the present invention should be considered to be included within the scope of the claims of the present invention.

Claims

1. A method for preparing a zinc anode for an aqueous zinc ion battery, characterized in that: The following steps are involved: Dissolve gluconic acid in deionized water to obtain a gluconic acid aqueous solution; wash a piece of zinc foil with deionized water and anhydrous ethanol to obtain Bare Zn; drop the gluconic acid solution on the bare Zn to react for 0.5-2h, then rinse with deionized water and dry, and cut the prepared zinc foil into sheets to obtain a 3D@101-Zn anode.

2. The method for preparing an aqueous zinc ion battery zinc anode according to claim 1, wherein When the gluconic acid solution is rinsed after reacting with the zinc foil, the number of rinses is 3 to 5 times.

3. The method for preparing an aqueous zinc ion battery zinc anode according to claim 1, wherein The concentration of the gluconic acid aqueous solution is 0.005-0.02 mol / L.

4. The method for preparing an aqueous zinc ion battery zinc anode according to claim 1, wherein: The zinc foil needs to be washed with deionized water and anhydrous ethanol before the reaction to remove surface oil and impurities.

5. The method for preparing an aqueous zinc ion battery zinc anode according to claim 1, wherein The gluconic acid used in the preparation process is of analytical grade.

6. The method for preparing a zinc anode for an aqueous zinc ion battery according to claim 1, wherein: The reaction time is 1 h to obtain the 3D@101-Zn anode with the best performance.

7. A zinc anode for an aqueous zinc ion battery, characterized in that: The preparation method is described in any one of claims 1 to 6.

8. The aqueous zinc ion battery zinc anode according to claim 7, characterized in that: Application in zinc ion batteries and zinc ion hybrid capacitors.

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