Coating material for metal zinc negative electrode and preparation method of zinc ion capacitor / battery

Abstract

The invention provides a coating material for a metal zinc negative electrode and a preparation method of a zinc ion capacitor / battery, and belongs to the technical field of electrochemistry. The coating material comprises MnO2 (at) GR, a conductive agent and a binder, the preparation method of the MnO2-coated GR comprises the following steps: uniformly mixing manganese sulfate and graphene oxide in water to obtain a solution A; adding a potassium permanganate solution into the solution A under a stirring condition, and uniformly mixing to obtain a solution B; the solution B is subjected to a hydrothermal reaction, and MnO2 (at) GR is obtained. When the surface of a zinc negative electrode is coated with the coating material, side reaction and dendritic crystal generation can be greatly inhibited, excellent stability is shown, meanwhile, dissolved Mn < 2 + > can be subjected to electro-deposition again on the surface of a positive electrode to form Mn3O4 during circulation, the Mn3O4 continues to participate in follow-up energy storage, and a novel zinc ion capacitor / battery with high energy density and high power density is formed at the same time.

Description

Technical Field

[0001] This invention relates to the field of electrochemical technology, and in particular to a coating material for a zinc metal anode and a method for preparing a zinc-ion capacitor / battery. Background Technology

[0002] Driven by the urgent need for global energy transition and sustainable development, the development of novel electrochemical energy storage devices has become a core issue in addressing the efficient utilization of intermittent renewable energy and the stable operation of smart grids. Lithium-ion batteries are currently widely used due to their high energy density, but their high cost and safety issues limit their further development. Compared to lithium-ion batteries, aqueous zinc-ion capacitors (AZICs) are considered an ideal choice for energy storage devices due to their low cost, inherent safety, environmental friendliness, and low redox potential. However, the practical application of AZICs still faces key bottlenecks, with the inherent problems of the zinc anode being particularly prominent. During charging and discharging, the zinc anode is prone to dendrite growth, hydrogen evolution reaction (HER), and corrosion. These problems not only lead to decreased coulombic efficiency and shortened cycle life, but in severe cases, can even puncture the separator and cause short circuits, greatly restricting the performance and stability of the device. Therefore, the rational modification and alteration of the zinc anode has become a key path to overcome the performance bottlenecks of AZICs.

[0003] Currently, researchers are improving the reversibility of zinc anodes through methods such as zinc electrode structure design, electrolyte optimization, coating modification, and diaphragm modification. Among these, coating modification has been widely studied due to its simple operation, significant effects, and outstanding advantages such as reducing direct contact between the zinc anode and the electrolyte, thereby suppressing side reactions on the zinc anode surface. For example, patent CN116387515A describes coating NASICON-type KTi2(PO4)3 onto the surface of zinc foil to prepare a zinc anode with an ion-gate structure interface protection layer. This protective layer allows only zinc ions to pass through to the anode while shielding electron conduction and guiding Zn... 2+ Uniform deposition forms a dendrite-free zinc anode. However, the dissolution of this type of coating can cause the crystal structure to collapse, thereby rendering its protective effect on the anode ineffective. Summary of the Invention

[0004] In view of this, the present invention aims to provide a coating material for a zinc anode and a method for preparing a zinc-ion capacitor / battery. In the coating material provided by the present invention, MnO2 on the surface of the zinc anode can suppress side reactions and has the ability to embed protons and zinc ions during charging, thereby suppressing hydrogen evolution, regulating uniform zinc ion deposition, and significantly improving the stability of the zinc anode. The graphene coating gives MnO2 better conductivity and structural stability, making its improvement on the zinc anode even more significant. Furthermore, during cycling, the coating partially dissolves, and the Mn... 2+Manganese-based oxides will be electrodeposited again on the positive electrode surface, forming a new type of zinc-ion capacitor / battery with both high energy density and high power density.

[0005] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of the present invention is a coating material for a zinc metal anode, comprising MnO2@GR, a conductive agent, and a binder; The preparation method of the MnO2@GR includes the following steps: Manganese sulfate and graphene oxide are mixed evenly in water to obtain solution A; Under stirring conditions, potassium permanganate solution is added to solution A and mixed thoroughly to obtain solution B; Solution B was subjected to a hydrothermal reaction to obtain the MnO2@GR.

[0006] The second technical solution of the present invention is a composite zinc electrode, comprising a zinc electrode and the above-mentioned coating material; the coating material is coated on the surface of the zinc electrode.

[0007] The third technical solution of the present invention is a zinc-ion battery, comprising the above-mentioned composite zinc electrode.

[0008] The fourth technical solution of the present invention is a zinc-ion capacitor, comprising the above-mentioned composite zinc electrode.

[0009] The present invention discloses the following technical effects: The MnO2@GR provided by this invention has a structure with MnO2 as the framework and a graphene layer coated on the surface. The graphene coating improves the conductivity of MnO2 while significantly enhancing its structural stability. Furthermore, the "three-dimensional electron transport network" formed by the graphene layer and MnO2 enables Zn... 2+ It can be rapidly and uniformly deposited, and coating it on the surface of zinc anodes can significantly suppress side reactions and dendrite formation, exhibiting excellent stability. Meanwhile, the dissolved Mn during cycling... 2+ Mn3O4 will be electrodeposited again on the positive electrode surface to continue participating in subsequent energy storage, forming a new type of zinc-ion capacitor / battery with both high energy density and high power density. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1The images shown are TEM and EDS images of the material prepared in Example 1 of this invention. In the images, a, b, and c are TEM images of α-MnO2@GR at scales of 1 μm, 100 nm, and 5 nm, respectively, and d, e, and f are EDS images of Mn, O, and C elements, respectively. Figure 2 The XRD patterns are of the materials prepared in Example 1 and Comparative Example 2 of this invention. Figure 3 Raman diagrams of the materials prepared in Example 1 and Comparative Example 2 of this invention; Figure 4 These are contact angle test diagrams of the electrodes in Embodiment 1, Comparative Example 1, and Comparative Example 2 of the present invention; Figure 5 This is a test comparison diagram of the electrodes of Embodiment 1, Comparative Example 1 and Comparative Example 2 of the present invention, where a is Tafel and b is LSV; Figure 6 These are cycle performance test diagrams of symmetrical batteries assembled with electrodes from Embodiment 1, Comparative Example 1, and Comparative Example 2 of the present invention. Figure 7 These are cycle performance test diagrams of capacitors assembled with electrodes from Embodiment 1, Comparative Example 1, and Comparative Example 2 of the present invention. Figure 8 The images show SEM and EDS images of the activated carbon positive electrode surface of the capacitor assembled in Embodiment 1 of the present invention before and after 10,000 cycles. In the images, a is the AC surface morphology before cycling, b, c, and d are the AC after 10,000 cycles at different scales, and e, f, g, and h are the EDS images of Mn, O, C, and Zn, respectively. Figure 9 This is a comparison of the XRD patterns on the surface of the activated carbon cathode of the capacitor assembled in Embodiment 1 of the present invention before and after 10,000 cycles. Detailed Implementation

[0012] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0013] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0014] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0015] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0016] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0017] The first aspect of the present invention provides a coating material for a zinc metal anode, comprising MnO2@GR, a conductive agent, and a binder; The preparation method of the MnO2@GR includes the following steps: Manganese sulfate and graphene oxide are mixed evenly in water to obtain solution A; Under stirring conditions, potassium permanganate solution is added to solution A and mixed thoroughly to obtain solution B; Solution B was subjected to a hydrothermal reaction to obtain the MnO2@GR.

[0018] In a preferred embodiment of the present invention, the mass ratio of manganese sulfate to graphene oxide is (5-31):1; and the concentration of graphene oxide in solution A is 1-2 mg / mL.

[0019] More preferably, the mass ratio of manganese sulfate to graphene oxide is 5:1, 8:1, 11:1, 14:1, 17:1, 20:1, 23:1, 26:1, 29:1, or 31:1.

[0020] In a preferred embodiment of the present invention, the molar ratio of potassium permanganate to manganese sulfate in solution B is (0.1-5):1.

[0021] More preferably, the molar ratio of potassium permanganate to manganese sulfate in solution B is 0.1:1, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, or 5:1.

[0022] In a preferred embodiment of the present invention, the concentration of the potassium permanganate solution is 0.1-0.2 mol / L.

[0023] In a preferred embodiment of the present invention, the temperature of the hydrothermal reaction is 80-200 °C and the time is 8-16 h.

[0024] More preferably, the hydrothermal reaction is carried out at temperatures of 80 ℃, 100 ℃, 120 ℃, 140 ℃, 160 ℃, 180 ℃, and 200 ℃ for 8 h, 10 h, 12 h, 14 h, and 16 h.

[0025] In a preferred embodiment of the present invention, after the hydrothermal reaction is completed, the step of collecting the solid product and drying the solid product is further included.

[0026] In a preferred embodiment of the present invention, the mass ratio of MnO2@GR, conductive agent and binder is (7-8):(1-2):1.

[0027] In a preferred embodiment of the present invention, the conductive agent is acetylene black; the binder is polyvinylidene fluoride (PVDF).

[0028] The second technical solution of the present invention is a composite zinc electrode, characterized in that it includes a zinc electrode and the above-mentioned coating material; the coating material is coated on the surface of the zinc electrode.

[0029] In this invention, the composite zinc electrode is prepared by: adding MnO2@GR, a conductive agent, and a binder to a solvent, grinding them, and obtaining a slurry; then coating the slurry onto the surface of a zinc electrode and drying it to obtain the composite zinc electrode; the solvent is NMP; the coating method is spin coating, blade coating, or spray coating; the drying temperature is 60-150 ℃, and the time is 12-24 h; the zinc electrode is a zinc sheet or zinc foil.

[0030] The third technical solution of the present invention is a zinc-ion battery, comprising the above-mentioned composite zinc electrode.

[0031] The fourth technical solution of the present invention is a zinc-ion capacitor, comprising the above-mentioned composite zinc electrode. In the zinc-ion capacitor, the above-mentioned composite zinc electrode is used as the negative electrode, and the positive electrode is activated carbon. After charge-discharge cycles, the positive electrode forms a manganese oxide / activated carbon structure.

[0032] Unless otherwise specified, the technical solutions described in this invention are all conventional solutions in the field, and the reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0033] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0034] Example 1 A composite zinc electrode is prepared by the following steps: (a) Slowly add 2 mg / ml of manganese sulfate. -1 In a graphene oxide solution, the mass ratio of the two is 8.6:1. After stirring and mixing, solution A is obtained. (b) Slowly add 0.2 mol / L of solution A while it is being stirred. -1 Potassium permanganate solution was prepared to obtain solution B, in which the molar ratio of manganese sulfate to potassium permanganate was 1:2. Solution B was stirred for another 1 h to ensure thorough mixing. (c) Pour the well-mixed solution B into a hydrothermal reactor and react at 120 °C for 12 h. After centrifugation with deionized water and drying in a vacuum oven at 60 °C for 12 h, the reaction product is obtained, which is α-MnO2@GR. (d) α-MnO2@GR, conductive agent (acetylene black), and binder (PVDF) were added to a solvent (NMP) at a mass ratio of 8:1:1 and then ground to obtain a slurry; (e) The slurry was coated onto the surface of zinc foil and dried in a vacuum oven at 60 °C for 12 h to obtain α-MnO2@GR@Zn.

[0035] Comparative Example 1 After polishing the zinc foil to remove the surface oxide layer, it is rinsed with ethanol and dried to obtain a bare zinc electrode.

[0036] Comparative Example 2 Similar to Example 1, except that the addition of graphene oxide was omitted, resulting in α-MnO2@Zn.

[0037] Effect Test Case The zinc electrodes obtained in Example 1, Comparative Example 1, and Comparative Example 2 were used to assemble zinc-ion symmetric cells and capacitors, respectively, and their electrochemical performance was tested.

[0038] Preparation of activated carbon AC positive electrode sheet: Specifically, activated carbon, acetylene black, and PVDF are mixed evenly in a ratio of 8:1:1, and NMP is used as a solvent to form a uniform slurry. This slurry is then coated onto the surface of carbon paper. The coated carbon paper is then dried in a vacuum oven at 60 °C for 12 h to obtain the positive electrode material (AC). The carbon paper before and after coating is weighed separately, and the difference in mass between the two is the loading of the coating material.

[0039] When assembling symmetrical cells, the electrodes prepared in Example 1, Comparative Example 1 and Comparative Example 2 were used as positive and negative electrodes, and an appropriate amount of 2 M ZnSO4 electrolyte was added. Glass fiber was used as a separator, and the electrochemical performance of the assembled symmetrical cells was tested.

[0040] When assembling zinc-ion capacitors, activated carbon AC electrodes were used as the positive electrode, and the electrodes prepared in Example 1, Comparative Example 1, and Comparative Example 2 were used as the negative electrode. An appropriate amount of 2 M ZnSO4 electrolyte was added, and glass fiber was used as the separator. The electrochemical performance of the assembled zinc-ion capacitors was then tested.

[0041] Figure 1 The images shown are TEM and EDS images of α-MnO2@GR synthesized in Example 1. Figure 1 In the image, a, b, and c are TEM images of α-MnO2@GR at scales of 1 μm, 100 nm, and 5 nm, respectively. It can be seen that α-MnO2@GR is in the form of nanowires. d, e, and f are EDS images of Mn, O, and C elements, respectively. It can be seen that Mn, O, and C elements are uniformly distributed on the nanowires, proving the successful coating of graphene.

[0042] Figure 2 The X-ray diffraction (XRD) patterns of α-MnO2@GR prepared in Example 1 and α-MnO2 prepared in Comparative Example 2 are shown. The XRD patterns confirm the successful synthesis of α-MnO2, while the graphene in α-MnO2@GR was not identified due to its low content.

[0043] Figure 3 Raman spectra of α-MnO2@GR prepared in Example 1 and α-MnO2 prepared in Comparative Example 2. As shown in the figure, the spectrum is located at 638 cm⁻¹. -1 The peak at 1337 cm⁻¹ can be attributed to the Mn-O bond, proving the successful preparation of α-MnO₂. -1 and 1595 cm -1 The peaks at the specified locations are the D and G peaks of graphene, indicating the presence of graphene on the surface of the α-MnO2@GR sample.

[0044] Figure 4 The figures show the contact angle test results for the electrodes of Comparative Example 1 and Comparative Example 2 in Example 1. Using 2 M ZnSO4 as the test solution, the contact angle of α-MnO2@Zn increased to 122.8° compared to bare zinc (84.8°), exhibiting hydrophobicity. The hydrophobicity of α-MnO2@GR@Zn was further improved compared to α-MnO2@Zn, with a contact angle reaching 131.2°.

[0045] Figure 5 This is a comparison chart of Tafel and LSV tests for electrodes in Example 1, Comparative Example 1, and Comparative Example 2. From the Tafel test comparison chart (... Figure 5 As shown in Figure a), the α-MnO2@GR@Zn electrode exhibits a more positive corrosion potential and a lower corrosion current compared to α-MnO2@Zn and bare zinc electrodes, demonstrating superior corrosion resistance. (From the LSV test comparison chart...) Figure 5As shown in Figure b), among the three electrodes, the hydrogen evolution current of α-MnO2@Zn is lower than that of the bare zinc electrode, while the α-MnO2@GR@Zn electrode has the lowest hydrogen evolution current. This indicates that the α-MnO2 coating can effectively suppress the hydrogen evolution reaction, and the graphene coating further improves its performance.

[0046] Figure 6 This is a long-cycle test diagram of the symmetrical cells with electrodes from Example 1, Comparative Example 1, and Comparative Example 2. As shown in the figure, at 20 mA cm⁻¹... -2 The current density is 0.5 mAh cm⁻¹ -2 Under the given areal capacity conditions, the symmetric cell assembled with α-MnO2@GR@Zn electrode can operate stably for over 1000 h, and the α-MnO2@Zn symmetric cell can operate for nearly 800 h, while the symmetric cell assembled with bare zinc electrode has unstable voltage after 200 h of operation, proving that the α-MnO2@GR modified coating significantly improves the stability of the zinc anode.

[0047] Figure 7 This is a comparative graph showing the long-cycle test results of the zinc-ion capacitors assembled with electrodes from Example 1, Comparative Example 1, and Comparative Example 2. As shown in the figure, at 1 A g… -1 At a current density of [value missing], the capacitor using the α-MnO2@GR@Zn electrode can operate stably for 10,000 cycles without degradation, maintaining a capacitance of 78.5 mAh g⁻¹. -1 The capacitor using the α-MnO2@Zn electrode maintained a capacity of 65 mAh g after 10,000 cycles. -1 However, the zinc-ion capacitor assembled with bare zinc electrodes experiences a continuous decrease in capacitance due to dendrite formation and side reactions on the zinc anode surface during cycling, reaching only 16 mAh g after 10,000 cycles. -1 .

[0048] Figure 8 SEM and EDS images of the AC positive electrode surface of the capacitor assembled in Example 1 before and after 10,000 cycles. Figure 8 In the diagram, 'a' represents the surface morphology of AC before the cycle. Figure 8 The middle bd represents AC after 10,000 cycles. A layer of nanoparticles can be seen grown on the surface of AC at this point. Further EDS testing was then performed on it. Figure 8 The surface of the sample was found to be mainly composed of Mn, O, and Zn. The uniform distribution of Mn and O indicates that a layer of manganese-based oxide has grown on the surface, and the large presence of Zn indicates that the manganese-based oxide has the function of accepting zinc ions for insertion.

[0049] Figure 9This is a comparison of XRD patterns on the activated carbon cathode surface of the capacitor assembled in Example 1 before and after 10,000 cycles. It can be seen that several additional peak pairs on the AC surface after 10,000 cycles correspond to Mn3O4, combined with... Figure 8 SEM and EDS tests confirmed that after the coating on the α-MnO2@GR@Zn surface partially dissolved, the generated Mn 2+ By electrodepositing Mn3O4 on the positive electrode, a novel zinc-ion capacitor / battery is generated, which enables the device capacity to continuously increase during cycling.

[0050] Example 2 A composite zinc electrode, the steps are as follows: (a) Slowly add 2 mg / ml of manganese sulfate. -1 In a graphene oxide solution, the mass ratio of the two is 8.6:1. After stirring and mixing, solution A is obtained. (b) Slowly add 0.2 mol / L of solution A while it is being stirred. -1 Potassium permanganate solution was prepared to obtain solution B, in which the molar ratio of manganese sulfate to potassium permanganate was 1.5:1. Solution B was stirred for another 1 h to ensure thorough mixing. (c) Pour the well-mixed solution B into a hydrothermal reactor and react at 180 °C for 12 h. After centrifugation with deionized water and drying in a vacuum oven at 60 °C for 12 h, the reaction product is obtained, which is β-MnO2@GR. (d) β-MnO2@GR, conductive agent (acetylene black), and binder (PVDF) were added to a solvent (NMP) at a mass ratio of 8:1:1 and then ground to obtain a slurry; (e) The slurry was coated onto the surface of zinc foil and dried in a vacuum oven at 60 °C for 12 h to obtain β-MnO2@GR@Zn.

[0051] The composite zinc electrode obtained in Example 2 was also subjected to electrochemical testing using the same method as in Example 1. The results show that the β-MnO2@GR@Zn electrode prepared in this example exhibits excellent electrochemical performance.

[0052] Example 3 A composite zinc electrode is prepared by the following steps: (a) Slowly add 2 mg / ml of manganese sulfate. -1 In a graphene oxide solution, the mass ratio of the two is 8.6:1. After stirring and mixing, solution A is obtained. (b) Slowly add 0.2 mol / L of solution A while it is being stirred. -1 Potassium permanganate solution was prepared to obtain solution B, in which the molar ratio of manganese sulfate to potassium permanganate was 1:10. Solution B was stirred for another 1 h to ensure thorough mixing. (c) Pour the well-mixed solution B into a hydrothermal reactor and react at 100 °C for 8 h. After centrifugation with deionized water and drying in a vacuum oven at 60 °C for 12 h, the reaction product is obtained, which is δ-MnO2@GR. (d) δ-MnO2@GR, conductive agent (acetylene black), and binder (PVDF) were added to a solvent (NMP) at a mass ratio of 8:1:1 and then ground to obtain a slurry; (e) The slurry was coated onto the surface of zinc foil and dried in a vacuum oven at 60 °C for 12 h to obtain δ-MnO2@GR@Zn.

[0053] The zinc electrode obtained in Example 3 was also subjected to electrochemical testing using the same method as in Example 1. The results showed that the δ-MnO2@GR@Zn electrode prepared in this example exhibits excellent electrochemical performance.

[0054] In summary, this invention synthesizes manganese dioxide with different crystal forms by controlling the hydrothermal time, temperature, and molar ratio of manganese sulfate and potassium permanganate. Based on this, by adding graphene oxide (GO), a graphene layer (MnO2@GR) can be uniformly coated onto the surface of MnO2 with different crystal forms. This is then combined with a conductive agent and binder to obtain a coating material. Electrochemical tests show that coating MnO2@GR onto the zinc anode surface effectively improves the corrosion resistance of the zinc anode. It suppresses hydrogen evolution by embedding protons for hydrogen storage during charging and achieves zinc storage by embedding zinc ions to regulate uniform zinc ion deposition, significantly suppressing zinc dendrite formation. Furthermore, during cycling, the coating partially dissolves, and the Mn... 2+ It will be electrodeposited again on the positive electrode surface as a manganese-based oxide and participate in subsequent energy storage, forming a new type of zinc-ion capacitor / battery with both high energy density and high power density.

[0055] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A coating material for zinc metal anodes, characterized in that, Includes MnO2@GR, conductive agent, and binder; The preparation method of MnO2@GR includes the following steps: Manganese sulfate and graphene oxide are mixed evenly in water to obtain solution A; Under stirring conditions, potassium permanganate solution is added to solution A and mixed thoroughly to obtain solution B; Solution B was subjected to a hydrothermal reaction to obtain the MnO2@GR.

2. The coating material for zinc metal anodes according to claim 1, characterized in that, The mass ratio of manganese sulfate to graphene oxide is (5-31):1; the concentration of graphene oxide in solution A is 1-2 mg / mL.

3. The coating material for zinc metal anodes according to claim 1, characterized in that, The molar ratio of potassium permanganate to manganese sulfate in solution B is (0.1-5):

1.

4. The coating material for a zinc metal anode according to claim 1, characterized in that, The hydrothermal reaction is carried out at a temperature of 80-200 ℃ for a duration of 8-16 h.

5. The coating material for a zinc metal anode according to claim 1, characterized in that, The mass ratio of MnO2@GR, conductive agent and binder is (7-8):(1-2):

1.

6. The coating material for a zinc metal anode according to claim 1 or 5, characterized in that, The conductive agent is acetylene black; the binder is polyvinylidene fluoride.

7. A composite zinc electrode, characterized in that, It includes a zinc electrode and the coating material of claim 1; the coating material is applied to the surface of the zinc electrode.

8. A zinc-ion battery, characterized in that, Includes the composite zinc electrode as described in claim 7.

9. A zinc-ion capacitor, characterized in that, Includes the composite zinc electrode as described in claim 7.

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