Modified zinc metal electrode and preparation and application thereof

Abstract

The invention belongs to the field of zinc battery materials, and particularly relates to a preparation method of a modified zinc metal electrode, a to-be-modified zinc metal negative electrode is placed in a polishing solution for surface modification treatment, and the modified zinc metal electrode is prepared; the polishing solution is a solution in which a compound shown as a formula 1 is dissolved. The invention also comprises the modified zinc metal electrode prepared by the preparation method as well as preparation and application of the modified zinc metal electrode. According to the invention, the zinc electrode is innovatively placed in the polishing solution containing the components in the formula 1 for surface chemical polishing and etching, so that the 002 crystal face can be accidentally and efficiently induced, the texture coefficient of 002 can be improved, moreover, the surface physical and chemical structure of the zinc electrode can be optimized, and the high-current cycle performance can be improved when the zinc electrode is used for assembling a zinc battery.

Description

Technical Field

[0001] This invention belongs to the field of zinc-ion batteries, specifically relating to the modification of zinc metal anodes in zinc batteries. Background Technology

[0002] With the increasing demand for renewable energy solutions, the necessity of developing electrochemical storage technologies that are both economically viable and environmentally friendly is becoming increasingly apparent. Aqueous zinc-ion batteries (ZIBs) have become strong competitors to traditional lithium-ion batteries due to their safety, efficiency, sustainability, and low cost. Furthermore, zinc anodes possess inherent characteristics of low redox potential and high theoretical specific capacity. However, the practical development of zinc metal anodes faces significant obstacles due to the diffusion and parasitic reactions of zinc dendrites. Commercial zinc foil is characterized by its rough surface and inhomogeneous passivation layer, inducing preferential nucleation of Zn... 2+ The uneven deposition of ions accelerates dendrite growth during cycling. This phenomenon leads to rapid electrolyte consumption and reduces coulombic efficiency (CE). Furthermore, parasitic reactions generate byproducts such as Zn₄SO₄(OH)₆·nH₂O, surface corrosion, and hydrogen evolution reaction (HER).

[0003] To address these issues, extensive research has been conducted, including designing zinc host structures, optimizing zinc interface structures, improving electrolyte composition, and developing functional membranes. Notably, the design of the electrolyte / electrode interface, particularly through the establishment of artificial solid electrolyte interphase (SEI) layers and the control of surface crystal orientation, has emerged as a promising approach to reduce dendrite growth and mitigate corrosion reactions.

[0004] However, applying these SEI layers using slurry casting methods with adhesives such as polyvinylidene fluoride (PVDF) introduces additional mass and volume, thereby reducing the volumetric and gravimetric capacity of ZIBs. Furthermore, poor adhesion between the SEI layer and Zn can lead to surface degradation, hindering the Zn²⁺ electroplating / stripping process and exacerbating dendrite growth. In addition, constructing Zn anodes with exposed (002) crystal faces has proven effective in suppressing dendrites because the (002) crystal faces exhibit a flat, regular hexagonal surface with the lowest surface energy, thus preventing the formation of zinc dendrites, HER, and corrosion reactions. For example, Chinese patent document CN118630124A describes the deposition of (002) oriented nano-zinc nuclei on the surface of a metal electrode substrate by physical vapor deposition; wherein the target material is a zinc metal target material, the target melting voltage is 1 to 10 kV, the current is 0.01 to 10 A, the polarity voltage is 10 to 100 kV, the deposition time is 1 s to 10 min, and the vacuum degree is 10⁻⁷ to 10⁻¹ Pa. In addition, existing technologies also include methods for forming a 002 intravenous zinc coating through electrodeposition. For example, Chinese patent document CN118610445A describes an electrodeposition method for constructing a three-dimensional ordered zinc metal anode material dominated by (002) crystal planes. This material includes a zinc metal substrate and a surface three-dimensional structure with (002) dominant crystal planes. The zinc metal substrate is a commercially available zinc foil, and the three-dimensional structure with (002) dominant crystal planes is obtained by controlling the current density and electrolyte concentration, while adding electrolyte additives to regulate the zinc metal electrodeposition process. As another example, Chinese patent document CN118472421A discloses an aqueous zinc-ion battery electrolyte, its preparation method, and the battery. The electrolyte contains 10 mmol / L to 50 mmol / L of an oxygen-containing cyclic sulfide additive, specifically 1,4-thiaoxane. This invention adds an oxygen-containing cyclic sulfide additive to the electrolyte of an aqueous zinc-ion battery. The additive inhibits the dissolution of the zinc anode SEI layer by regulating the activity of water molecules near the zinc side, thereby constructing a stable zinc anode / electrolyte interface. This achieves preferential orientation control of the zinc metal (002) crystal plane, thereby suppressing dendrite formation and side reactions and improving the electrochemical performance of the zinc-ion battery.

[0005] In summary, current methods for manufacturing (002) planar exposed zinc anodes, such as calcination, cumulative roll welding, and DC electrodeposition, require complex preparation processes and incur significant manufacturing costs, posing a major obstacle to widespread production and application. Furthermore, materials produced by existing methods are difficult to adapt to the requirements of high-current cycling applications. Therefore, the demand for simple, economical, effective, and reliable zinc anode surface modification methods is constantly increasing, necessitating the provision of a simple, rapid, efficient, environmentally friendly, and low-cost zinc foil surface modification method. Summary of the Invention

[0006] To address the problems of existing zinc anode modification methods being complex and difficult to adapt to high-current cycling requirements, the primary objective of this invention is to provide a method for preparing a modified zinc metal electrode, aiming to provide a modified zinc anode whose surface physicochemical structure can be optimized based on simple chemical polishing, thereby optimizing its adaptability to high-current cycling requirements.

[0007] The second objective of this invention is to provide a modified zinc metal electrode prepared by the aforementioned method and its application in zinc batteries.

[0008] A third objective of this invention is to provide a zinc battery comprising the modified zinc metal electrode.

[0009] A method for preparing a modified zinc metal electrode involves placing the zinc metal negative electrode to be modified in a polishing solution for surface modification treatment to obtain the modified zinc metal electrode.

[0010] The polishing fluid is a solution containing a compound of formula 1;

[0011]

[0012] The R is a C1 to C6 alkyl, substituted alkyl, aryl, or substituted aryl group; wherein the substituents on the substituted alkyl or substituted aryl group include at least one of a C1 to C6 alkyl group or an electron-withdrawing group.

[0013] This invention innovatively places the zinc electrode in a polishing solution containing the components of Formula 1 for surface chemical polishing and etching. This can unexpectedly and efficiently induce the 002 crystal plane, improve the texture coefficient of 002, and optimize its surface physicochemical structure. When used to assemble zinc batteries, it can improve high-current cycling performance.

[0014] In this invention, the zinc metal anode to be modified can be any elemental zinc or zinc alloy electrode, for example, it can be an ultra-thin zinc foil with a thickness between 10 and 50 μm.

[0015] This invention demonstrates that the physicochemical structure of Formula 1 is key to synergistically improving the chemical polishing effect of zinc surfaces, optimizing their 002 crystal planes, and enhancing their high-current cycling performance. Based on this, further optimization of its structure and the concentration and time of the processing stages can further improve the surface-inducing effect and further enhance the high-current performance of the prepared material.

[0016] In this invention, Formula 1 includes at least one of Formula 1A and Formula 1B;

[0017]

[0018] Wherein, R1 is a C1 to C6 alkyl group;

[0019] R2 is a C1-C6 alkyl group or an electron-withdrawing group, wherein the electron-withdrawing group is preferably at least one selected from halogen, trifluoromethyl, nitro, and carbonyl. The carbonyl group is, for example, an aldehyde, ester, or amide group.

[0020] This invention also shows that chemical polishing of zinc batteries using the Formula 1B structure, especially Formula 1B where R2 is an electron-withdrawing group, can unexpectedly further enhance the interface and crystal plane of the surface etching, which helps to further enhance the texture coefficient of the 002 crystal plane. Moreover, it can further enhance the cycling stability of the modified electrode under high current.

[0021] In this invention, the polishing fluid is made of water, or a mixture of water and an organic solvent, wherein the organic solvent is miscible with water. The organic solvent is, for example, at least one of alcohol, DMSO, and DMF. This invention also demonstrates that, based on chemical polishing according to Formula 1, further control of the concentration and processing time of Formula 1 can further enhance the polishing effect, further improve the 002 texture coefficient, and enhance the cycling performance under high current.

[0022] In this invention, the concentration of the polishing liquid of Formula 1 is 0.05-0.5M, preferably 0.1-0.35M, and more preferably 0.1-0.25M.

[0023] In this invention, the surface modification treatment temperature is 15–30°C.

[0024] Preferably, the surface modification time is 1 to 20 minutes, more preferably 4 to 12 minutes, and even more preferably 4 to 8 minutes.

[0025] In this invention, the processing stage can be carried out in an inert atmosphere such as nitrogen or argon.

[0026] The present invention also provides a modified zinc metal electrode prepared by the preparation method described above.

[0027] In this invention, the preparation method can endow the prepared material with a special surface etching physicochemical structure, and the material prepared by the method can unexpectedly exhibit excellent electrochemical performance, especially cycling performance under high current.

[0028] The present invention also provides an application of the modified zinc metal electrode prepared by the above preparation method, which is used as a negative electrode in the preparation of zinc batteries.

[0029] Based on conventional principles and ideas, the modified zinc metal anode described in this invention can be used to assemble the desired zinc battery.

[0030] The present invention also provides a zinc metal battery, wherein the negative electrode is a modified zinc metal electrode prepared by the preparation method described in the present invention.

[0031] The zinc metal battery of the present invention, except for the modified zinc metal electrode described in the present invention, may have other known structures and components.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] This invention provides a simple and rapid chemical polishing method for developing a novel stable zinc anode material. This technology can effectively optimize the physicochemical structure of the zinc metal surface, particularly enabling the etching and construction of a highly oriented 002 interface. The modified zinc anode prepared by this method exhibits excellent electrochemical performance, especially demonstrating superior stability even at high current densities and large areal capacities. Attached Figure Description

[0034] Figure 1 Cyclic impedance diagrams of batteries prepared from zinc foil (materials before polishing in Example 1, after polishing in Example 1, and after polishing in Example 4B) after being immersed in polishing solution for different times.

[0035] Figure 2 A symmetrical battery prepared from the zinc foil modified in Example 1 was tested at a current density of 1 mA / cm². 2 -1mAh / cm 2 10mA / cm 2 -5mAh / cm 2 Voltage-time plot

[0036] Figure 3 Cycle number-specific capacity / coulombic efficiency curves of full cells prepared using zinc foil modified in Example 1 at 0.2 A / g and rate conditions.

[0037] Figure 4 XRD images of the zinc foil modified according to Example 1 and commercial zinc foil are compared.

[0038] Figure 5 XRD crystal orientation ratio comparison between the zinc foil modified in Example 1 and commercial zinc foil. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to specific embodiments, but the present invention is not limited to the following embodiments. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods; unless otherwise specified, the materials and reagents used are commercially available.

[0040] Example 1

[0041] (1) The polishing agent is dispersed in a solvent (water in this case) to obtain a polishing liquid. The polishing agent in this case is of formula a. Its concentration is 0.15M;

[0042] (2) Transfer the polishing liquid to a cool place at room temperature, take a zinc foil with a thickness of 50μm (bare Zn), cut it to a suitable size, put the zinc foil in it, cover it, and then vibrate and polish it at room temperature (25±5℃) for 5 minutes to obtain the modified material.

[0043] (3) After the soaking time is reached, the zinc foil is taken out, the surface is rinsed with alcohol, and then ultrasonically cleaned in deionized water for 30 minutes. After taking it out, it is naturally air-dried to obtain modified zinc foil (TsOH@Zn), which can be directly used to prepare batteries.

[0044] test:

[0045] 1.1: The modified zinc foil prepared in Example 1 was cleaned and cut into circular electrodes with a radius of 7 mm. In an atmospheric environment, the zinc electrode, glass fiber separator, prepared zinc electrode, and nickel foam were assembled into a CR2025 coin cell. A 2 mol / L zinc sulfate electrolyte was added, and the cells were finally sealed using a battery packaging machine. AC impedance testing was performed on an electrochemical workstation, with a test frequency range of 0.01-10 Hz. 6 Hz.

[0046] AC impedance test results are as follows Figure 1 As shown, from Figure 1 It can be seen that the electrochemical impedance of the battery composed of zinc foil treated by the method described in Example 1 is significantly reduced, that is, removing the passivation layer on the surface of the zinc foil is beneficial to improving the kinetics of the electrochemical reaction.

[0047] 1.2: At 25℃, a current density of 1 mA / cm² was used respectively. 2 The surface capacity is 1mAh / cm². 2 and a current density of 10 mA / cm 2 The surface capacity is 5mAh / cm². 2 Current density is 20 mA / cm 2 The surface capacity is 10mAh / cm². 2 The assembled symmetrical battery was subjected to charge-discharge tests to investigate the electrochemical performance of the material. The testing instrument was the Blue Electric Electrochemical Measurement System.

[0048] Test results are as follows Figure 2 As shown in the figure, the voltage-time curves reveal that the battery life of the zinc foil treated by the method described in Example 1 is significantly improved, even at a current density of 1 mA / cm². 2 The surface capacity is 1mAh / cm². 2Under these conditions, the lifespan can be increased tenfold, and it can stably cycle for nearly 1500 hours even under high current density and large capacity conditions. In contrast, batteries assembled with untreated zinc foil short-circuited after only 200 hours of operation. The lifespan is increased by more than seven times, even under a high depth of discharge (34.2%) and a capacity of 10 mAh / cm². 2 It can still cycle for 300 hours and has excellent high-current performance.

[0049] 1.3: Using the zinc foil treated in Example 1 and NH4 + -V2O5 cathodes were assembled into button cells and subjected to charge-discharge cycles at a current of 2A / g (based on the mass of the cathode active material) on a Blue Electric charge-discharge tester. At the same time, rate tests were performed at 0.2-0.5-1-2-3-0.2A / g.

[0050] Test results are as follows Figure 3 As shown, from Figure 3 The cycle count-specific capacity / coulombic efficiency curves show that the treated zinc foil exhibits a significantly improved discharge specific capacity, reaching 360 mAh / g. It demonstrates excellent cycle stability and also exhibits higher specific capacity in rate testing. Furthermore, it can withstand cycling under various current conditions and recovers to its high specific capacity after restoring the initial current density. In contrast, batteries assembled with untreated zinc foil have low specific capacity, fail rapidly under high-rate discharge, and exhibit poor battery stability.

[0051] 1.4: To verify the effect of the treatment process in Example 1 on the crystal orientation of the zinc foil surface, XRD characterization tests were performed on the surface of the treated zinc foil and the surface of the original commercial zinc foil.

[0052] Test results are as follows Figure 4 As shown, by Figure 5 It can be seen that the strength of the (002) crystal plane of the zinc foil is significantly improved after treatment. The strength ratio of the (002) crystal plane to other crystal planes is calculated, and the results are as follows: Figure 5 As shown, I (002) / I (100) The crystal orientation intensity ratio increased from 7.71 for commercial zinc foil to 14.7. (002) / I (101) The crystal orientation intensity ratio was increased from 1.35 for commercial zinc foil to 2.46, nearly doubling, successfully constructing a zinc substrate with preferred crystal orientation.

[0053] In summary, the technical solution of this application can obtain a smooth zinc anode substrate with preferred crystal orientation through simple and efficient chemical polishing, thereby achieving cycle stability under high current and high capacity.

[0054] Example 2

[0055] Compared to Example 1, the only difference is that the polishing agent in step 1 is changed. The experimental groups are as follows:

[0056] Group A: Polishing agent is of the following type.

[0057] Group B: Polishing agent is of formula c

[0058] All other operations and parameters are the same as in Example 1.

[0059] Example 3

[0060] Compared to Example 1, the only difference is that the concentration of the polishing agent in the polishing slurry was changed. The experimental groups were as follows:

[0061] Group A: The concentration of the polishing agent is 0.1M;

[0062] Group B: The concentration of the polishing agent is 0.2M;

[0063] Group C: The concentration of the polishing agent is 0.35M;

[0064] All other operations and parameters are the same as in Example 1.

[0065] Example 4

[0066] Compared to Example 1, the only difference is the change in polishing time; the experimental groups are as follows:

[0067] Group A: Polishing time is 10 minutes;

[0068] Group B: Polishing time is 20 minutes;

[0069] All other operations and parameters are the same as in Example 1.

[0070] Example 5

[0071] Compared with Example 2B, the only difference is that the polishing agent is of formula c, and the solvent is a water-DMSO mixture with a volume ratio of 8:2. All other operations and parameters are the same as in Example 1.

[0072] Comparative Example 1

[0073] Compared with Example 1, the only difference is that the polishing agent was not added to the polishing liquid; all other operations and parameters are the same as in Example 1.

[0074] Comparative Example 2

[0075] Compared to Example 1, the only difference is that the polishing solution uses the comparative compound. Replace the polishing agent, and all other operations and parameters are the same as in Example 1.

[0076] Comparative Example 3

[0077] Compared with Example 1, the only difference is that a 0.15M sodium hydroxide aqueous solution is used as the polishing solution, while all other operations and parameters are the same as in Example 1.

[0078] Comparative Example 4

[0079] Compared with Example 1, the only difference is that a 0.15M sulfuric acid aqueous solution is used as the polishing solution, while all other operations and parameters are the same as in Example 1.

[0080] Comparative Example 5

[0081] Compared with Example 1, the only difference is that a 0.15M citric acid aqueous solution is used as the polishing solution, while other operations and parameters are the same as in Example 1.

[0082] Comparative Example 6

[0083] Compared with Example 1, the only difference is that when assembling the battery, the electrolyte of Formula a is added, and all other operations and parameters are the same as in Example 1.

[0084] The test structures for each case are as follows:

[0085] Table 1

[0086]

[0087]

[0088] As can be seen from Examples 1 and 2, the polishing agent of the present invention, especially the preferred polishing agent with electron-withdrawing groups and benzene rings, can obtain a better 002 crystal facet induction effect. In addition, it can effectively improve the stability of the polished material under high current. Furthermore, in the water-organic solvent system, this surface-induced polishing effect can be further optimized, and its performance under high current can be further enhanced.

Claims

1. A method for preparing a modified zinc metal electrode, characterized in that, The zinc metal anode to be modified is placed in a polishing solution for surface modification treatment to obtain a modified zinc metal electrode. The polishing fluid is a solution containing a compound of formula 1; The R is a C1 to C6 alkyl, substituted alkyl, aryl, or substituted aryl group; wherein the substituents on the substituted alkyl or substituted aryl group include at least one of a C1 to C6 alkyl group or an electron-withdrawing group.

2. The method for preparing the modified zinc metal electrode as described in claim 1, characterized in that, The zinc metal anode to be modified is an ultrathin zinc foil with a thickness between 10 and 50 μm.

3. The method for preparing the modified zinc metal electrode as described in claim 1, characterized in that, Formula 1 includes at least one of Formula 1A and Formula 1B; Wherein, R1 is a C1 to C6 alkyl group; The R2 is a C1-C6 alkyl group or an electron-withdrawing group, wherein the electron-withdrawing group is preferably at least one of halogen, trifluoromethyl, nitro, and carbonyl.

4. The method for preparing the modified zinc metal electrode as described in claim 1, characterized in that, The polishing fluid is made of water or a mixture of water and an organic solvent, wherein the organic solvent is a water-miscible organic solvent.

5. The method for preparing the modified zinc metal electrode as described in claim 1, characterized in that, In the polishing liquid, the concentration of Formula 1 is 0.05-0.5M, preferably 0.1-0.35M.

6. The method for preparing the modified zinc metal electrode as described in claim 1, characterized in that, The surface modification treatment temperature is 15–30°C.

7. The method for preparing the modified zinc metal electrode as described in claim 1, characterized in that, The surface modification time is 1–20 min, and further 4–12 min.

8. A modified zinc metal electrode prepared by the preparation method according to any one of claims 1 to 7.

9. The application of a modified zinc metal electrode prepared by the preparation method according to any one of claims 1 to 7, characterized in that, It is used as the negative electrode in the preparation of zinc batteries.

10. A zinc metal battery, characterized in that, Its negative electrode is a modified zinc metal electrode prepared by the preparation method according to any one of claims 1 to 7.

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