Zinc composite negative electrode and preparation method and application thereof

Abstract

The application belongs to the field of aqueous zinc ion batteries, and proposes a zinc composite negative electrode, a preparation method thereof and an application thereof. The zinc composite negative electrode 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 plating layer. The metal is one or more than two of Bi, Ni, Sn, Te, MXene and carbon material. The current collector layer and the zinc foil layer are combined by physical rolling. The composite negative electrode is used in a zinc ion battery. The service life of the zinc ion battery is prolonged, and the coulomb efficiency of the zinc ion battery under high zinc utilization can be improved. The 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] This invention belongs to the field of aqueous zinc-ion batteries, and relates to a zinc composite negative electrode, its preparation method, and its application. Background Technology

[0002] In recent years, aqueous zinc-ion batteries have received widespread attention in the industry due to their advantages such as environmental friendliness, high safety, and low cost. Among them, the zinc anode possesses a low redox potential (-0.763 V vs. SHE), abundant reserves, low cost, and high theoretical capacity (820 mAh·g). -1 5855 mAh·cm -3 Zinc anodes offer advantages such as [missing information - likely related to advantages]. However, the dendrite growth, hydrogen evolution reaction, and passivation problems currently existing in zinc anodes severely limit the commercial application of zinc metal batteries. To solve these problems, researchers often use excess zinc to ensure a continuous supply of zinc anode active materials, which leads to extremely low zinc utilization in the anode. Simultaneously, the use of excess zinc increases battery costs and reduces actual energy density. Therefore, finding a suitable zinc anode current collector has become a breakthrough point in addressing the problems of excess zinc and side reactions. The design of a three-dimensional anode can increase the contact area between the electrode and electrolyte and the number of zinc nucleation sites, while reducing local current and nucleation overpotential, thereby generating a uniform electric field and Zn²⁺ ion distribution, achieving uniform zinc deposition and slowing down dendrite growth.

[0003] Chinese patent CN111916744A discloses a liquid metal composite anode for zinc-ion batteries, its preparation method, and its application. This composite anode includes a zinc metal substrate and a liquid alloy layer, with the liquid alloy layer disposed on the surface of the zinc metal substrate. However, the high cost of some liquid metals limits their industrial application, and some liquid metals also exhibit poor chemical stability, readily reacting with other substances.

[0004] Chinese patent CN113193158A discloses a three-dimensional zinc composite anode, its preparation method, and its application. The anode comprises a porous metal top layer and a zinc bottom layer, with the zinc portion filling the porous metal layer. The three-dimensional zinc composite anode has a dual interface. The preparation method of this invention involves first placing zinc and porous metal materials side-by-side in close contact, and then using a mechanical deformation method to control pressure and strain rate, causing the zinc portion to fill the porous metal layer, resulting in the final product. However, this method may result in interface problems; due to the potential difference between the zinc metal and the metal material, a hydrogen evolution reaction may occur.

[0005] Chinese patent CN114613980A discloses a zinc-ion battery composite anode, its preparation method, and its application. The anode includes a zinc metal substrate and a functionalized carbon dot layer. The functionalized carbon dot layer is formed by coating functionalized carbon dots, a binder, and a solvent onto the surface of the zinc metal substrate. The functionalized carbon dots are carbon dots doped with at least one of nitrogen, oxygen, and sulfur. While coating the zinc anode surface with a carbon dot layer creates an artificial SEI layer that protects the zinc anode, it also increases the interfacial resistance and makes zinc nucleation more difficult.

[0006] Currently reported current collector solutions are either complex to prepare or expensive, failing to achieve both goals and hindering commercialization. Therefore, developing a simple preparation method that does not significantly increase costs while substantially improving zinc anode utilization is urgently needed. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a zinc composite anode, its preparation method, and its applications. By electroplating an inert metal onto a stainless steel mesh and then combining it with a zinc metal anode, the problems of potential difference between zinc metal and stainless steel mesh, hydrogen evolution reaction, and zinc nucleation are solved. Furthermore, the method of wrapping the stainless steel mesh with zinc foil on both sides also solves the problem of easy detachment of the composite anode.

[0008] The technical solution of the present invention:

[0009] The first aspect of the present invention is to provide a zinc composite negative electrode (SSM-Bi-Zn) having a current collector layer and two zinc foil layers, the current collector layer being between the two zinc foil layers, the surface of the current collector layer having a metal plating layer, the metal being one or more of Bi, Ni, Sn, Te, MXene, and carbon materials, and the current collector layer and the zinc foil layers being bonded together by a physical rolling method.

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

[0011] Furthermore, the thickness of the metal coating is 5~100μm. Preferably, it is 5~50μm, and more preferably, it is 10~30μm.

[0012] Furthermore, the thickness of the zinc foil layer is 30~200μm. Preferably, it is 80~120μm, and more preferably 100μm.

[0013] The second aspect of the present invention is a method for preparing the zinc composite negative electrode, wherein firstly, a metal coating is plated on a current collector, and then the current collector plated with the metal coating is bonded to the zinc foil by a physical rolling process.

[0014] Furthermore, the plating method is one of electroplating, immersion, spraying, scraping, or chemical deposition.

[0015] Furthermore, the physical roller pressing method requires adjusting the gap between the two rollers to 0.8~1.2mm, preferably 1mm. The roller pressing temperature is 20~30℃, preferably 25℃.

[0016] Preferably, Bi metal is electroplated onto the stainless steel mesh, and the electroplating solution has a concentration of 0.001~0.1 mol·L⁻¹. -1 A bismuth nitrate aqueous solution, preferably with a concentration of 0.001~0.05 mol·L⁻¹. -1 Further optimization was performed using 0.01~0.05 mol·L⁻¹. -1 The electroplating time is 10~100s, preferably 20~60s, and more preferably 60s. The electroplating current density is 1~7 mA·cm. -2 The preferred electroplating current density is 1~6 mA·cm. -2 Further optimization of 4~6 mA·cm -2 .

[0017] This invention produces a zinc composite negative electrode (SSM-Bi-Zn) through a simple physical rolling process and electroplating of an inert metal onto a current collector. This not only increases the number of zinc nucleation sites and reduces local current, but also generates a uniform electric field and Zn. 2+ The distribution of ions ensures uniform zinc deposition and slows dendrite growth. Furthermore, the inert metal element Bi in the current collector framework provides a low lattice mismatch at the current collector / zinc interface, further suppressing dendrite formation. Bi is considered to possess high HER suppression capability and zinc affinity, and also enhances zinc deposition density.

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

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

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

[0021] 1. The preparation method of this invention is simple, low-cost, and easy to scale up for mass production. The prepared zinc composite anode (SSM-Bi-Zn) can suppress zinc dendrites and improve zinc utilization, which is beneficial to the industrial application of zinc-ion batteries.

[0022] 2. Stainless steel mesh current collectors can not only increase the number of zinc nucleation sites and average current density, thus generating a uniform electric field and Zn 2+The distribution of ions is important, but the potential difference between the stainless steel mesh and zinc itself can accelerate the hydrogen evolution reaction, and the stainless steel mesh has poor zinc affinity. Unlike previous methods, combining inert metals with zinc only solves the surface problem; it doesn't address the issues of increasing zinc nucleation sites or reducing zinc usage, thus failing to improve zinc utilization. Therefore, this invention proposes electroplating inert metals onto the current collector. This not only solves the hydrogen evolution problem but also ensures a uniform zinc ion distribution, uniform deposition, and prevents clogging of the current collector's framework. Furthermore, the inert metal element provides a low lattice mismatch at the current collector / zinc interface, better suppressing dendrite formation. Moreover, the good conductivity of the inert metal ensures rapid charge transfer even with zinc coverage, ensuring more thorough subsequent stripping, thereby significantly improving the electrochemical stability and coulombic efficiency of zinc-based batteries.

[0023] 3. This invention can significantly improve the cycle performance of zinc-ion button and soft-pack batteries, increasing the utilization rate of zinc-ion batteries from 25% to 60% without affecting the cycle life. Attached Figure Description

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

[0025] Figure 2 Cycle performance diagrams of the prepared SSM-Bi-Zn, SSM-Zn, Bi@Zn-SSM and Zn anodes (zinc foil) used to assemble zinc-ion symmetric coin cells;

[0026] Figure 3 Cycle performance diagrams of the prepared SSM-Bi-Zn, SSM-Zn, Bi@Zn-SSM and Zn anodes (zinc foil) used to assemble zinc-ion symmetric coin cells;

[0027] Figure 4 Cycle performance diagram of the Zn negative electrode (zinc foil) prepared for Comparative Example 1 used to assemble a zinc-ion symmetric coin cell;

[0028] Figure 5 Cyclic performance diagrams of SSM-Bi-Zn, SSM-Zn, and Bi@Zn-SSM prepared for use in assembling zinc-ion symmetric coin cells;

[0029] Figure 6 XRD patterns of zinc surfaces after testing SSM-Bi-Zn and SSM-Zn prepared for use in zinc-ion symmetric coin cells;

[0030] Figure 7The images show the physical images of the zinc anode (zinc foil) after the pure zinc foil prepared for Comparative Example 1 was used to assemble a zinc-ion symmetric coin cell and the scanning electron microscope (SEM) image of the zinc surface. (a) is a physical image of the pure zinc foil after cycling; (b) is a SEM image of the pure zinc foil at 10 μm after cycling; and (c) is a SEM image of the pure zinc foil at 1 μm after cycling.

[0031] Figure 8 The images show the actual zinc anode and the scanning electron microscope (SEM) image of the zinc surface after testing the SSM-Zn prepared for Comparative Example 2 in a zinc-ion symmetric coin cell. (a) is the actual image of the SSM-Zn after cycling; (b) is the SEM image of the SSM-Zn after cycling at 10 μm; and (c) is the SEM image of the SSM-Zn after cycling at 1 μm.

[0032] Figure 9 The images show the actual zinc anode and the scanning electron microscope (SEM) image of the zinc surface after testing the SSM-Bi-Zn composite anode prepared in Example 1 for use in a zinc-ion symmetric coin cell. (a) is an actual image of the SSM-Bi-Zn composite anode after cycling; (b) is an SEM image of the SSM-Bi-Zn composite anode at 10 μm after cycling; and (c) is an SEM image of the SSM-Bi-Zn composite anode at 1 μm after cycling.

[0033] Figure 10 The prepared SSM-Bi-Zn and SSM-Zn were used to assemble zinc-ion asymmetric coin cells for testing coulombic efficiency diagrams, where (a) shows the coulombic efficiency of SSM-Zn and SSM-Bi-Zn at 3 mA·cm⁻¹. -2 (a) Time-voltage plots of SSM-Zn and SSM-Bi-Zn at 3mA·cm; (b) Time-voltage plots of SSM-Zn and SSM-Bi-Zn at 3mA·cm -2 The number of cycles under the given conditions - Coulomb efficiency plot.

[0034] Figure 11 The prepared SSM-Bi-Zn, SSM-Zn, and Zn anodes were immersed in zinc sulfate electrolyte to observe the gas production. (a) is a picture of the initial immersion stage; (b) is a picture of the immersion stage after one week.

[0035] Figure 12 Cyclic performance diagram of SSM-Bi-Zn prepared in Example 1 used to assemble zinc-ion symmetric pouch cells. Detailed Implementation

[0036] The present invention will be further described in detail below through specific embodiments. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0037] Preparation Example 1

[0038] Add 3.4g of bismuth nitrate to 700mL of deionized water, stir for 10 minutes, and mix well to obtain bismuth nitrate electroplating solution.

[0039] After cleaning, bismuth was electroplated onto the stainless steel mesh using a current density of 6 mA·cm². -2 The electroplating time is 60 seconds. After the electroplating is completed, the stainless steel mesh is soaked in deionized water for cleaning and then dried.

[0040] The dried bismuth-plated stainless steel mesh and two 100μm thick zinc foils were bonded together by physical rolling, with the stainless steel mesh sandwiched between the two zinc foil layers, to obtain the SSM-Bi-Zn zinc composite negative electrode. The two zinc foils and the bismuth-plated stainless steel mesh were placed in a rolling mill with a roller gap of 1mm and a rolling temperature of 25℃. The rolling was stopped after about 10 cycles, and the electrode sheets were cut for later use.

[0041] Preparation of Comparative Example 1

[0042] Cut 100μm thick zinc foil into 1cm pieces. 2 The size and shape are used to prepare Zn negative electrodes.

[0043] Preparation of Comparative Example 2

[0044] After cleaning, the stainless steel mesh is directly bonded to a 100μm thick zinc foil using a physical rolling method to obtain the SSM-Zn negative electrode. The parameters of the physical rolling are 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 and stirred for 10 minutes until homogeneous, yielding a bismuth nitrate solution. A 100 μm zinc foil was immersed in the bismuth nitrate solution for 60 seconds, then removed and washed to obtain a modified zinc foil. This modified zinc foil was then bonded to a clean stainless steel mesh using a physical rolling process to obtain the Bi@Zn-SSM anode. The parameters for the physical rolling process were the same as in Example 1.

[0047] Application Example 1

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

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

[0050] Figure 1 For asymmetric coin cells at 3 mA·cm -2 Coulombic efficiency tests were conducted with 60% DOD. It can be seen that the first cycle of SSM-Bi-Zn plating at 60 seconds yielded the highest coulombic efficiency, which increased with the number of cycles. However, as the plating time was extended to 70 seconds, the first cycle coulombic efficiency decreased, indicating that a longer plating time is not necessarily better; 60 seconds is the optimal plating time.

[0051] Figure 2 The coin cells assembled using the zinc anode (zinc foil) of Comparative Example 1, the SSM-Zn of Comparative Example 2, the SSM-Bi-Zn of Example 1, and the Bi@Zn-SSM of Comparative Example 3 were tested at 1 mA·cm⁻¹. -2 1 mAh·cm -2 The test performance is shown in the figure. As can be seen from the figure, zinc foil alone can only operate for less than 100 hours, while combining it with stainless steel mesh can achieve 900 hours. After bismuth plating the stainless steel mesh, the combined advantages of bismuth metal and the stainless steel current collector allow the coin cell to operate for over 1000 hours. The battery cycle life demonstrates that the presence of a current collector and inert metals can significantly improve the lifespan of zinc-ion batteries. Furthermore, combining bismuth and zinc foil with a stainless steel mesh shows a significant performance difference, indicating that good performance is only achieved when bismuth is present in the current collector stainless steel mesh.

[0052] Figure 3 The coin cells assembled using the zinc anode (zinc foil) of Comparative Example 1, the SSM-Zn of Comparative Example 2, the SSM-Bi-Zn of Example 1, and the Bi@Zn-SSM of Comparative Example 3 were tested at 3 mA·cm⁻¹. -2 3 mAh·cm -2 The test performance is shown in the figure. As can be seen from the figure, the zinc foil alone can only run for less than 50 hours. The performance of the battery after combining bismuth with zinc foil and stainless steel mesh is not as good as that of pure zinc foil. The zinc foil alone combined with stainless steel mesh can run for more than 200 hours. After bismuth is plated on the stainless steel mesh, the combination of the dual advantages of bismuth metal element and stainless steel mesh current collector enables the button cell battery to run for about 300 hours.

[0053] Figure 4 A coin cell assembled using the zinc anode prepared in Comparative Example 1 was tested at 3 mA·cm⁻¹. -2Performance was tested at 60% DOD. The graph shows that the zinc foil alone failed after less than one cycle.

[0054] Figure 5 The coin cells assembled using SSM-Zn (Comparative Example 2), SSM-Bi-Zn (Example 1), and Bi@Zn-SSM (Comparative Example 3) were tested at 3 mA·cm⁻¹. -2 Performance was tested at 60% DOD. The graph shows that the battery with bismuth combined with zinc foil and stainless steel mesh only lasts about 50 hours, while the battery with zinc foil combined with stainless steel mesh can last over 100 hours. After bismuth plating the stainless steel mesh and then rolling it together with zinc foil, the lifespan of the coin cell battery is extended to about 200 hours. High zinc utilization places greater demands on the zinc anode, truly demonstrating the role of the current collector in zinc-ion batteries.

[0055] Figure 6 Coin cells assembled using the zinc anode prepared in Comparative Example 1, the SSM-Zn of Comparative Example 2, and the SSM-Bi-Zn of Example 1 were tested at 3 mA·cm⁻¹. -2 The XRD patterns after running for the same amount of time at 60% DOD are shown. The figures show that a large amount of basic zinc sulfate byproducts appear on the surface of ordinary zinc foil, while only a small amount of byproducts appear on the zinc surfaces of SSM-Zn and SSM-Bi-Zn. Furthermore, the 002 crystal plane is superior to the 100 crystal plane, indicating that the stainless steel mesh provides deposition sites for zinc, and the inert bismuth metal helps to ensure uniform zinc deposition.

[0056] Figure 7 A coin cell assembled using the zinc anode prepared in Comparative Example 1 was tested at 3 mA·cm⁻¹. -2 Scanning electron microscope (SEM) images obtained after running for the same amount of time at 60% DOD. From Figure 7 As can be seen in (a) of the diagram, under high zinc utilization, the zinc anode on one side has been completely consumed, leaving only half of the electrode. From... Figure 7 As can be seen from (b) and (c), the zinc foil surface is uneven and rough, and dendrites appear on the zinc surface.

[0057] Figure 8 The coin cell assembled using SSM-Zn prepared in Comparative Example 2 was tested at 3 mA·cm⁻¹. -2 Scanning electron microscope (SEM) images obtained after running for the same amount of time at 60% DOD. From Figure 8 As can be seen in (a) under high zinc utilization, with the presence of stainless steel mesh, both zinc electrodes are present and their surfaces are intact. From the scanning electron microscope images (b) and (c), it can be seen that the zinc foil surface is uniform and flat, which indicates that the stainless steel mesh current collector can serve as a zinc deposition site.

[0058] Figure 9The coin cell assembled using the SSM-Bi-Zn prepared in Example 1 was tested at 3 mA·cm⁻¹. -2 Scanning electron microscope (SEM) images obtained after running for the same amount of time at 60% DOD. From Figure 9 As shown in (a), under high zinc utilization, the presence of stainless steel mesh ensures the presence of zinc electrodes on both sides with intact surfaces. Scanning electron microscopy images (b) and (c) reveal a uniform and smooth zinc foil surface, indicating that the stainless steel mesh current collector can serve as a zinc deposition site. Furthermore, it was found that zinc deposition exhibits a deposition orientation after bismuth metal electroplating on the stainless steel mesh, demonstrating that the inert metal plays an inductive role in zinc deposition.

[0059] Figure 10 The asymmetric coin cells assembled from SSM-Zn in Comparative Example 2 and SSM-Bi-Zn in Example 1 were tested at 3 mA·cm⁻¹. -2 The coulombic efficiency diagram under 100% DOD is shown. From (a), it can be seen that further improving zinc utilization results in complete zinc ion stripping. With only the stainless steel mesh current collector present, the zinc ions cannot return to their original sites, leading to failure after only about 100 hours of operation. However, after electroplating inert bismuth onto the stainless steel mesh current collector, all zinc ions are stripped. When they are electroplated back onto the stainless steel mesh current collector, the presence of bismuth allows for uniform zinc deposition, improving coulombic efficiency. From (b), it is known that the first-cycle coulombic efficiency of SSM-Zn is 90.94%, and the average coulombic efficiency is 97.85%. The first-cycle coulombic efficiency of SSM-Bi-Zn is 92.36%, and the average coulombic efficiency is 98.16%. With the assistance of inert metal Bi, it can be seen that not only is the first-cycle coulombic efficiency improved, but the average coulombic efficiency is also improved.

[0060] Figure 11 The zinc anode 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 directly observed that no bubbles are generated in the presence of stainless steel mesh, proving that stainless steel mesh does not induce hydrogen evolution reaction.

[0061] Figure 12 To assemble the SSM-Bi-Zn negative electrode of Example 1 into a pouch cell, the stainless steel mesh was cut into 80cm pieces. 2 After electroplating a bismuth layer according to the conditions of Example 1, the zinc foil was cut into 160cm pieces. 2 The size is determined by rolling a bismuth-plated stainless steel mesh wrapped with zinc foil to obtain an SSM-Bi-Zn composite negative electrode. Excess material is then trimmed, and a separator is inserted between two identical electrodes. Sufficient electrolyte is added, and the electrode is sealed and allowed to stand for operation. The electrolyte is 2 mol·L⁻¹. -1 Zinc sulfate, at 3 mA·cm -2The test performance at 60% DOD shows that amplified electrode testing did not shorten battery life; on the contrary, the advantages of the electrode were more evident during the amplification process. This also proves the feasibility and simplicity of electrode amplification.

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

Claims

1. Use of a zinc composite anode in a zinc-ion battery, characterized in that, 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 1-2 mol / L -1 The zinc composite negative electrode has a current collector layer and two zinc foil layers, the current collector layer is between the two zinc foil layers, the thickness of the zinc foil layer is 30-200 mu m, the surface of the current collector layer has a 5-50 mu m plating layer, the plating layer is a metal plating layer or a non-metal plating layer, wherein the metal plating layer is one or more of Bi, Ni, Sn and MXene, and the non-metal plating layer is one or more of Te and carbon material, the current collector layer and the zinc foil layer are combined by physical rolling, the gap between the two rollers needs to be adjusted to 0.8-1.2 mm, and the rolling temperature is 20-30 DEG C, and the current collector layer is one or more of stainless steel mesh, titanium mesh, copper mesh, three-dimensional nano-copper array, nickel alloy mesh and alloy mesh.

2. Use according to claim 1, characterized in that, The preparation method of the zinc composite negative electrode is as follows: firstly, plating a metal plating layer on the current collector, and then combining the current collector with the zinc foil through physical rolling.

3. Use according to claim 2, characterized in that, The plating method is one of electroplating, immersion, spraying, blade coating and chemical deposition.

4. Use according to claim 3, characterized in that, A stainless steel mesh is electroplated with metal Bi using an aqueous bismuth nitrate solution with a concentration of 0.001-0.1 mol·L -1 -1 for 10-100 s, and a plating current density of 1-7 mA·cm -2 -2 is set.

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