Zinc composite negative electrode and preparation method and application thereof

Abstract

The invention belongs to the field of aqueous zinc ion batteries, and provides a zinc composite negative electrode and a preparation method and application thereof. The zinc composite negative electrode is provided with a current collector layer and two zinc foil layers, the current collector layer is arranged between the two zinc foil layers, the surface of the current collector layer is provided with a metal coating, metal is one or more than two of Bi, Ni, Sn, Te, MXene and a carbon material, and the current collector layer and the zinc foil layers are combined in a physical rolling mode. The composite negative electrode is used for the zinc ion battery, so that the service life of the zinc ion battery is prolonged, and the coulombic efficiency of the zinc ion battery under the high zinc utilization rate can be improved. Button-type and soft-package zinc ion batteries assembled by using the electrolyte have excellent cycle life. The preparation process is simple and is suitable for large-scale production.

Description

Technical Field

[0001] The present invention belongs to the field of aqueous zinc ion batteries, and relates to a zinc composite negative electrode, a preparation method thereof and an application thereof. Background Art

[0002] In recent years, aqueous zinc ion batteries have received extensive attention in the industry due to their advantages such as environmental friendliness, high safety and low cost. Among them, the zinc negative electrode has a low redox potential (-0.763 V vs. SHE), rich reserves, low cost and high theoretical capacity (820 mAh·g -1 , 5855 mAh·cm -3 ). However, the current problems of dendrite growth, hydrogen evolution reaction and passivation of the zinc negative electrode seriously limit the commercial application of zinc metal batteries. To solve these problems, researchers often use excessive zinc to ensure the continuous supply of the active material of the zinc negative electrode, which results in extremely low zinc utilization rate of the negative electrode. At the same time, the use of excessive zinc increases the cost of the battery and reduces the actual energy density. Therefore, in order to solve the problems of excessive zinc and side reactions, finding a suitable zinc negative electrode current collector becomes the breakthrough point. The design of a three-dimensional negative electrode can increase the contact area between the electrode and the electrolyte and the number of zinc nucleation sites, while reducing the local current and nucleation overpotential, thereby generating a uniform electric field and the distribution of Zn²⁺ ions, realizing uniform zinc deposition and slowing down dendrite growth.

[0003] Chinese Patent CN111916744A discloses a liquid metal composite negative electrode for a zinc ion battery, a preparation method thereof and an application thereof. The composite negative electrode includes a zinc metal matrix and a liquid alloy layer, and the liquid alloy layer is disposed on the surface of the zinc metal matrix. However, the cost of some liquid metals is relatively high, which limits industrial application, and the chemical stability of some liquid metals is poor and they are prone to react with other substances.

[0004] Chinese Patent CN113193158A discloses a three-dimensional zinc composite negative electrode, a preparation method thereof and an application thereof, including a porous metal top layer and a metal zinc bottom layer, and the metal zinc is partially filled in the porous metal layer. The three-dimensional zinc composite negative electrode has a double interface. The preparation method of the three-dimensional zinc composite negative electrode of the present invention first places the metal zinc and the porous metal material side by side and closely in contact with each other up and down, and then controls the pressure and strain rate through a mechanical deformation method to make the metal zinc partially fill the porous metal layer to obtain the product. The composite negative electrode prepared by this method may have interface problems. Due to the potential difference between the zinc metal and the metal material, the hydrogen evolution reaction may occur.

[0005] Chinese Patent CN114613980A discloses a composite zinc anode and its preparation method and application, including a zinc metal matrix and a functionalized carbon dot layer. The functionalized carbon dot layer is formed by coating a mixture of functionalized carbon dots, binder, and solvent on the surface of the zinc metal matrix. The functionalized carbon dots are carbon dots doped with at least one of nitrogen, oxygen, and sulfur. By coating a carbon dot layer on the zinc anode, the artificial SEI layer can protect the zinc anode, but it will increase the interfacial resistance and the difficulty of zinc nucleation.

[0006] The current reported current collector solutions are either complex in preparation method or expensive in cost, and it is impossible to balance both, so it is also affecting the commercialization process. Therefore, it is urgent to develop a preparation method that is simple, does not significantly increase the cost, and has a significantly improved utilization rate of the zinc anode. Summary of the Invention

[0007] The object of the present invention is to overcome the deficiencies of the prior art and provide a zinc composite anode and its preparation method and application. By electroplating an inert metal on a stainless steel mesh and then compounding it with a zinc metal anode, the problems of potential difference, hydrogen evolution reaction, and zinc nucleation between the zinc metal and the stainless steel mesh are solved. Moreover, the problem of easy detachment of the composite anode is also solved by using the method of wrapping the stainless steel mesh with zinc foils on both sides.

[0008] The technical solution of the present invention:

[0009] The first aspect of the present invention provides a zinc composite anode (SSM-Bi-Zn), which has a current collector layer and two zinc foil layers. The current collector layer is between the two zinc foil layers, and the surface of the current collector layer has a metal coating. The metal is one or more of Bi, Ni, Sn, Te, MXene, and carbon materials. The current collector layer and the zinc foil layer are combined by physical rolling.

[0010] Further, the current collector layer is one or more of a stainless steel mesh, a titanium mesh, a copper mesh, a three-dimensional nano-copper array, a nickel alloy mesh, and an alloy mesh.

[0011] Further, the thickness of the metal coating is 5-100 μm. Preferably 5-50 μm, more preferably 10-30 μm.

[0012] Further, the thickness of the zinc foil layer is 30-200 μm. Preferably 80-120 μm, more preferably 100 μm.

[0013] The second aspect of the present invention is the preparation method of the zinc composite anode. First, a metal coating is plated on the current collector, and then the current collector plated with the metal coating is combined with the zinc foil by physical rolling.

[0014] Further, the plating method is one of electroplating, dipping, spraying, scraping, and chemical deposition.

[0015] Further, for the physical roll pressing method, the gap between the two roller wheels needs to be adjusted to 0.8 - 1.2 mm, preferably 1 mm. The roll pressing temperature is 20 - 30 °C, preferably 25 °C.

[0016] Preferably, metal Bi is electroplated on the stainless - steel mesh, and the electroplating solution is an aqueous bismuth nitrate solution with a concentration of 0.001 - 0.1 mol·L -1 The concentration of the aqueous bismuth nitrate solution is preferably 0.001 - 0.05 mol·L -1 , and further preferably 0.01 - 0.05 mol·L -1 . The electroplating time is 10 - 100 s, preferably 20 - 60 s, and further preferably 60 s. The electroplating current density is 1 - 7 mA·cm -2 . The electroplating current density is preferably 1 - 6 mA·cm -2 , and further preferably 4 - 6 mA·cm -2 .

[0017] The zinc composite negative electrode (SSM - Bi - Zn) prepared by the present invention through a simple physical roll pressing and electroplating an inert metal on the current collector not only increases the number of zinc nucleation sites, reduces the local current, thereby generating a uniform electric field and the distribution of Zn 2+ ions, realizes uniform zinc deposition and slows down dendrite growth. In addition, the inert metal element Bi in the current collector skeleton makes the current collector / zinc interface have a low lattice mismatch, which can better inhibit dendrites. The Bi metal element is considered to have high HER inhibition ability and zincophilicity, and enhances the zinc deposition density.

[0018] The third aspect of the present invention is the application of the zinc composite negative electrode in a zinc - ion battery.

[0019] Further, the positive electrode of the zinc - ion battery is manganese - based, vanadium - based, Prussian blue, etc., and the electrolyte is a zinc sulfate solution with a concentration of 1 - 2 mol·L -1 .

[0020] Advantages and technical effects of the present invention:

[0021] 1. The preparation method of the present invention has simple steps, low cost, is easy to scale up preparation and mass production. The prepared zinc composite negative electrode (SSM - Bi - Zn) can inhibit zinc dendrites and improve zinc utilization rate, which is beneficial to the industrial application of zinc - ion batteries.

[0022] 2. The stainless - steel mesh current collector can not only increase the number of zinc nucleation sites and the average current density, thereby generating a uniform electric field and Zn 2+The distribution of ions, however, the potential difference existing between the stainless steel mesh and zinc itself will lead to an accelerated hydrogen evolution reaction and the poor zincophilicity of the stainless steel mesh. Different from the past, if an inert metal and a zinc metal are combined, only the surface problem can be solved, and the problems of increasing the zinc nucleation sites and reducing the zinc consumption cannot be solved, and the zinc utilization rate cannot be improved. Therefore, the present invention proposes to electroplate an inert metal on the current collector, which not only solves the hydrogen evolution problem but also the inert metal will evenly distribute zinc ions, deposit evenly and will not block the skeleton of the current collector. In addition, the inert metal element enables the current collector / zinc interface to have a low lattice mismatch, which can better inhibit dendrites. Moreover, the good electrical conductivity of the inert metal ensures rapid charge transfer even in the case of zinc coverage, ensuring more complete subsequent stripping, thus significantly improving the electrochemical stability and Coulomb efficiency of the zinc-based battery.

[0023] 3. The present invention can greatly improve the cycling performance of zinc-ion coin and soft-pack batteries. When the utilization rate of zinc-ion batteries is increased from 25% to 60%, the cycle life is not affected. Brief Description of the Drawings

[0024] Figure 1 Coulomb efficiency diagram of SSM-Bi-Zn electroplated for different times prepared in Example 1 for assembling a zinc-ion asymmetric coin battery;

[0025] Figure 2 Cycling performance diagram of SSM-Bi-Zn, SSM-Zn, Bi@Zn-SSM and Zn negative electrode (zinc foil) prepared for assembling a zinc-ion symmetric coin battery;

[0026] Figure 3 Cycling performance diagram of SSM-Bi-Zn, SSM-Zn, Bi@Zn-SSM and Zn negative electrode (zinc foil) prepared for assembling a zinc-ion symmetric coin battery;

[0027] Figure 4 Cycling performance diagram of the Zn negative electrode (zinc foil) prepared in Comparative Example 1 for assembling a zinc-ion symmetric coin battery;

[0028] Figure 5 Cycling performance diagram of SSM-Bi-Zn, SSM-Zn, Bi@Zn-SSM for assembling a zinc-ion symmetric coin battery;

[0029] Figure 6 XRD diagram of the zinc surface after testing for SSM-Bi-Zn, SSM-Zn prepared for assembling a zinc-ion symmetric coin battery;

[0030] Figure 7The physical picture of the zinc negative electrode (zinc foil) after the pure zinc foil prepared in Comparative Example 1 was used to assemble and test the zinc-ion symmetric button battery, and the scanning electron microscope image of the zinc surface. Among them, (a) is the physical picture of the pure zinc foil after cycling; (b) is the SEM image of the pure zinc foil after cycling at 10 μm; (c) is the SEM image of the pure zinc foil after cycling at 1 μm.

[0031] Figure 8 The physical picture of the zinc negative electrode after the SSM-Zn prepared in Comparative Example 2 was used to assemble and test the zinc-ion symmetric button battery, and the scanning electron microscope image of the zinc surface. Among them, (a) is the physical picture of the SSM-Zn after cycling; (b) is the SEM image of the SSM-Zn after cycling at 10 μm; (c) is the SEM image of the SSM-Zn after cycling at 1 μm.

[0032] Figure 9 The physical picture of the zinc negative electrode after the SSM-Bi-Zn prepared in Example 1 was used to assemble and test the zinc-ion symmetric button battery, and the scanning electron microscope image of the zinc surface. Among them, (a) is the physical picture of the SSM-Bi-Zn composite negative electrode after cycling; (b) is the SEM image of the SSM-Bi-Zn composite negative electrode after cycling at 10 μm; (c) is the SEM image of the SSM-Bi-Zn composite negative electrode after cycling at 1 μm.

[0033] Figure 10 The Coulomb efficiency diagram of the SSM-Bi-Zn and SSM-Zn prepared for assembling the zinc-ion asymmetric button battery test. Among them, (a) is the time-voltage diagram of the SSM-Zn and SSM-Bi-Zn at 3 mA·cm -2 ; (b) is the cycle number-Coulomb efficiency diagram of the SSM-Zn and SSM-Bi-Zn at 3 mA·cm -2

[0034] Figure 11 The physical picture of the gas production observed when the prepared SSM-Bi-Zn, SSM-Zn, and Zn negative electrodes were immersed in the zinc sulfate electrolyte. Among them, (a) is the physical picture at the initial stage of immersion; (b) is the physical picture after soaking for one week.

[0035] Figure 12 The cycle performance diagram of the SSM-Bi-Zn prepared in Example 1 for assembling the zinc-ion symmetric soft-pack battery. Detailed Description of the Specific Embodiment

[0036] The present invention will be further described in detail below through specific embodiments. The following embodiments are only descriptive and not restrictive, and the protection scope of the present invention cannot be limited thereby.

[0037] Preparation of Example 1

[0038] ​3.4 g of bismuth nitrate was added to 700 mL of deionized water, stirred for 10 minutes, and mixed evenly to obtain a bismuth nitrate electroplating solution.

[0039] After cleaning the stainless steel mesh, bismuth element was electroplated onto the stainless steel mesh by electroplating method, and the current density of electroplating was 6 mA·cm -2 , the electroplating time was 60 s. After that, the stainless steel mesh was soaked in deionized water, cleaned and dried.

[0040] The dried bismuth-coated stainless steel mesh and two zinc foils with a thickness of 100 μm were combined together by physical rolling method, and the stainless steel mesh was between the two zinc foil layers to obtain an SSM-Bi-Zn zinc composite negative electrode. The two zinc foils and the bismuth-coated stainless steel mesh were placed in a rolling press. The roll gap of the rolling press was 1 mm, the rolling temperature was 25 °C, and the rolling stopped after about 10 times. The electrode sheet was cut and reserved for use.

[0041] Preparation of Comparative Example 1

[0042] The zinc foil with a thickness of 100 μm was cut into a shape of 1 cm 2 in size to prepare a Zn negative electrode.

[0043] Preparation of Comparative Example 2

[0044] After cleaning the stainless steel mesh, it was directly combined with a zinc foil with a thickness of 100 μm by physical rolling method to obtain an SSM-Zn negative electrode. The parameters of physical rolling were the same as those in Example 1.

[0045] Preparation of Comparative Example 3

[0046] 3.4 g of bismuth nitrate was added to 700 mL of deionized water, stirred for 10 minutes, and mixed evenly to obtain a bismuth nitrate solution. The 100-μm zinc foil was soaked in the bismuth nitrate solution for 60 s and then taken out, cleaned to obtain a modified zinc foil. The modified zinc foil and the cleaned stainless steel mesh were combined by physical rolling method to obtain a Bi@Zn-SSM negative electrode. The parameters of physical rolling were the same as those in Example 1.

[0047] Application Example 1

[0048] 11.5024 g of zinc sulfate heptahydrate was added to 20 mL of deionized water, stirred for one hour, and mixed evenly to obtain a pure 2 mol·L -1 ZnSO4 electrolyte.

[0049] The stainless steel meshes electroplated with bismuth layers for 10 s, 20 s, 30 s, 40 s, 50 s, 60 s, and 70 s respectively were cut into 1 cm 2The electrode sheet is used as the positive electrode. The stainless steel mesh with bismuth layers electroplated for 10 s, 20 s, 30 s, 40 s, 50 s, 60 s, and 70 s respectively and two 100-μm zinc foils are roll-pressed and then cut into 1 cm 2 The electrode sheet is used as the negative electrode and assembled into an asymmetric coin cell for testing.

[0050] Figure 1 For the asymmetric coin cell at 3 mA·cm -2 , the coulombic efficiency test at 60% DOD. It can be seen that the first-cycle coulombic efficiency of SSM-Bi-Zn electroplated for 60 s is the highest. As the number of cycles increases, the coulombic efficiency also increases. However, when the electroplating time is extended to 70 s, it is found that the first-cycle coulombic efficiency decreases. It can be seen that the longer electroplating time is not necessarily better, and the optimal electroplating time is 60 s.

[0051] Figure 2 For the coin cells assembled with the zinc negative electrode (zinc foil) of Comparative Example 1, SSM-Zn of Comparative Example 2, SSM-Bi-Zn of Example 1, and Bi@Zn-SSM of Comparative Example 3 at 1 mA·cm -2 , 1 mAh·cm -2 The test performance. It can be seen from the figure that the pure zinc foil can only operate for less than 100 hours. After combining with the stainless steel mesh, it can operate for 900 hours. After electroplating bismuth on the stainless steel mesh, with the double advantages of bismuth metal elements and the stainless steel mesh current collector, the coin cell can operate for more than 1000 hours. It can be seen from the battery cycle life that the presence of the current collector and inert metal can greatly improve the life of zinc-ion batteries. And when bismuth and zinc foil are combined and then combined with the stainless steel mesh, it can be seen that there are very large differences in performance. It can be seen that only when bismuth exists on the stainless steel mesh current collector can good performance be achieved.

[0052] Figure 3 For the coin cells assembled with the zinc negative electrode (zinc foil) of Comparative Example 1, SSM-Zn of Comparative Example 2, SSM-Bi-Zn of Example 1, and Bi@Zn-SSM of Comparative Example 3 at 3 mA·cm -2 , 3 mAh·cm -2 The test performance. It can be seen from the figure that the pure zinc foil can only operate for less than 50 hours. After bismuth is combined with zinc foil and stainless steel mesh, the battery performance is not as excellent as that of the pure zinc foil. After the pure zinc foil is combined with the stainless steel mesh, it can operate for more than 200 hours. After electroplating bismuth on the stainless steel mesh, with the double advantages of bismuth metal elements and the stainless steel mesh current collector, the coin cell can operate for about 300 hours.

[0053] Figure 4 For the coin cell assembled with the zinc negative electrode prepared in Comparative Example 1 at 3 mA·cm -2, the test performance at 60% DOD. As can be seen from the figure, the pure zinc foil can only run for less than 1 cycle and then fails.

[0054] Figure 5 The coin cells assembled with the SSM-Zn of Comparative Example 2, the SSM-Bi-Zn of Example 1, and the Bi@Zn-SSM of Comparative Example 3 at 3 mA·cm -2 , the test performance at 60% DOD. As can be seen from the figure, the battery with bismuth combined with zinc foil and stainless steel mesh can only run for about 50 hours, while the zinc foil combined with stainless steel mesh can run for more than 100 hours. After plating bismuth on the stainless steel mesh and then roll-pressing and combining it with the zinc foil, the life of the coin cell is extended to about 200 hours. At high zinc utilization rates, the test of the zinc negative electrode is more severe, and only then can the role of the current collector in zinc-ion batteries be truly reflected.

[0055] Figure 6 The coin cells assembled with the zinc negative electrode prepared in Comparative Example 1, the SSM-Zn of Comparative Example 2, and the SSM-Bi-Zn of Example 1 at 3 mA·cm -2 , the XRD patterns after running for the same time at 60% DOD. As can be seen from the figure, a large amount of by-product zinc sulfate basic salt appears on the surface of the ordinary zinc foil, while only a small amount of by-products appear on the surface of the zinc in SSM-Zn and SSM-Bi-Zn, and the 002 crystal plane is better than the 100 crystal plane. It can be concluded that the stainless steel mesh provides zinc deposition sites, and the inert bismuth metal can help zinc deposit evenly.

[0056] Figure 7 The coin cells assembled with the zinc negative electrode prepared in Comparative Example 1 at 3 mA·cm -2 , the scanning electron microscope images after running for the same time at 60% DOD. From Figure 7 (a), it can be seen that at high zinc utilization rates, one side of the zinc negative electrode has been consumed, and only half of the electrode remains. From Figure 7 (b) and (c), it can be seen that the surface of the zinc foil is uneven and not flat, and dendrites appear on the surface of the zinc.

[0057] Figure 8 The coin cells assembled with the SSM-Zn prepared in Comparative Example 2 at 3 mA·cm -2 , the scanning electron microscope images after running for the same time at 60% DOD. From Figure 8 (a), it can be seen that at high zinc utilization rates, with the presence of the stainless steel mesh, both sides of the zinc electrode exist and the surface is intact. From the scanning electron microscope images (b) and (c), it can be seen that the surface of the zinc foil is uniform and flat. It can be concluded that the stainless steel mesh current collector can serve as a zinc deposition site.

[0058] Figure 9The SEM image of the button cell assembled with SSM-Bi-Zn prepared in Example 1 after running for the same time under 3 mA·cm -2 and 60% DOD. As can be seen from (a) in Figure 9 , at high zinc utilization rate and in the presence of stainless steel mesh, both zinc electrodes on both sides exist and the surface is intact. As can be seen from SEM images (b) and (c), the surface of the zinc foil is uniform and flat, indicating that the stainless steel mesh current collector can serve as a zinc deposition site. It was also found that after electroplating bismuth metal on the stainless steel mesh, zinc deposition has a deposition orientation, proving that the inert metal plays an inducing role in zinc deposition.

[0059] Figure 10 The Coulomb efficiency diagrams of the asymmetric button cells assembled with SSM-Zn of Comparative Example 2 and SSM-Bi-Zn of Example 1 under 3 mA·cm -2 and 100% DOD. As can be seen from (a), when further increasing the zinc utilization rate and all zinc ions are stripped, in the presence of only the stainless steel mesh current collector, zinc ions cannot return to the original site, so it can only operate for more than 100 hours and then fails. However, after electroplating the inert metal bismuth on the stainless steel mesh current collector, when all zinc ions are stripped and then electroplated back onto the stainless steel mesh current collector, due to the presence of bismuth, zinc can be deposited uniformly and the Coulomb efficiency can be improved. As can be seen from (b), the initial Coulomb efficiency of SSM-Zn is 90.94% and the average Coulomb efficiency is 97.85%. While the initial Coulomb efficiency of SSM-Bi-Zn is 92.36% and the average Coulomb efficiency is 98.16%. With the assistance of the inert metal Bi, it can be seen that not only the initial Coulomb efficiency is improved, but also the average Coulomb efficiency is increased.

[0060] Figure 11 The zinc negative electrode of Comparative Example 1, SSM-Zn of Comparative Example 2, and SSM-Bi-Zn of Example 1 were immersed in zinc sulfate electrolyte. It can be visually observed that in the presence of stainless steel mesh, no bubbles are generated, proving that the stainless steel mesh does not induce the occurrence of hydrogen evolution reaction.

[0061] Figure 12 The SSM-Bi-Zn negative electrode of Example 1 was assembled into a soft-pack battery. The stainless steel mesh was cut into a size of 80 cm 2 . After electroplating a bismuth layer under the conditions of Example 1, the zinc foil was cut into a size of 160 cm 2 . The zinc foil wrapped the stainless steel mesh electroplated with a bismuth layer and was roll-pressed to obtain the SSM-Bi-Zn composite negative electrode. Then the excess part was cut off. A separator was inserted between two identical electrode sheets, and after adding sufficient electrolyte and encapsulating, it was left to stand and operate. The electrolyte was 2 mol·L -1 zinc sulfate, under 3 mA·cm -2, Test performance at 60% DOD. It can be seen that when testing the enlarged electrode, the battery life is not shortened. Instead, during the enlargement process, the advantages of the electrode sheet can be more clearly demonstrated. This also proves the feasibility and simplicity of enlarging the electrode sheet.

[0062] In summary, the above embodiments are only for explaining the relevant principles and implementation methods, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made to the present invention without departing from the principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A zinc composite negative electrode, characterized in that, It has a current collector layer and two zinc foil layers, the current collector layer is between the two zinc foil layers, the surface of the current collector layer has a metal coating, and the metal is one or more of Bi, Ni, Sn, Te, MXene, and carbon materials. The current collector layer and the zinc foil layer are combined by physical rolling.

2. The zinc composite negative electrode according to claim 1, wherein, The current collector layer is one or more of a stainless steel mesh, a titanium mesh, a copper mesh, a three-dimensional nano-copper array, a nickel alloy mesh, and an alloy mesh.

3. The zinc composite negative electrode according to claim 1, wherein, The thickness of the metal coating is 5 to 100 μm.

4. The zinc composite negative electrode according to claim 1, wherein The thickness of the zinc foil layer is 30 to 200 μm.

5. The preparation method of the zinc composite negative electrode according to any one of claims 1-4, characterized in that, First, a metal coating is plated on the current collector, and then the current collector with the metal coating is combined with the zinc foil by physical rolling.

6. The preparation method of the zinc composite negative electrode according to claim 5, characterized in that, The plating method is one of electroplating, soaking, spraying, scraping, and chemical deposition.

7. The preparation method of the zinc composite negative electrode according to claim 5, characterized in that, For the physical rolling method, the gap between the two rollers needs to be adjusted to 0.8 to 1.2 mm, and the rolling temperature is 20 to 30 °C.

8. The preparation method of the zinc composite negative electrode according to claim 5, characterized in that, Electroplate metallic Bi on a stainless-steel mesh, and use an aqueous bismuth nitrate solution with a concentration of 0.001~0.1 mol·L -1 as the electroplating solution. The electroplating time is 10 s~100 s, and the electroplating current density is set to 1~7 mA·cm -2 .

9. Application of a zinc composite negative electrode as described in any one of claims 1-4 in a zinc ion battery.

10. The application according to claim 9, wherein The positive electrode of the zinc-ion battery is manganese-based, vanadium-based, or Prussian blue, and the electrolyte is a zinc sulfate solution with a concentration of 1 to 2 mol·L -1 .

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