Method for modifying the interface of a metal zinc negative electrode of an aqueous zinc-ion battery

Abstract

The application discloses a kind of water-based zinc ion battery metal zinc negative electrode interface modification method, to solve the technical problem that too much zinc dendrite is generated on the surface of water-based zinc ion battery electrode, side reaction occurs, belongs to the technical field of energy materials.The modification method includes the following steps: zinc foil is poured into phosphoric acid solution and etched surface;Glucose and PVP are configured into aqueous solution, adjust PH, obtain solution A;AgNO3 is configured into aqueous solution, obtain solution B;Solution B is slowly dropped into solution A, black suspension is obtained, PVP and PAM are added as binder, and gelled coating material is obtained after stirring;Gelled coating material is coated on the etched zinc foil, and water-based zinc ion battery metal zinc negative electrode is obtained after drying.After modification, zinc foil can accelerate the diffusion kinetics of Zn 2+ , ensure the uniform nucleation and efficient deposition of Zn 2+ , inhibit H2 release, reduce polarization and hydrogen evolution corrosion, improve the conductivity of pole piece, and improve the cycle performance and stability of battery.

Description

Technical Field

[0001] This invention belongs to the field of energy materials technology, specifically a method for modifying the interface of the metallic zinc anode in an aqueous zinc-ion battery. Background Technology

[0002] Electrochemical energy storage technology (i.e., batteries) has attracted increasing attention due to its advantages such as ease of use, low environmental pollution, and high conversion efficiency. Currently, lithium-ion batteries dominate the energy storage market, but the organic electrolyte system they use poses safety hazards such as toxicity and flammability. Furthermore, the low abundance and high cost of metallic lithium resources severely hinder its large-scale application. To address this issue, researchers have proposed using safer aqueous electrolytes to replace organic electrolytes in the development of novel aqueous metal-ion batteries. Among many metals, zinc has abundant natural reserves, low price, and high energy density (820 mA·h·g). -1 5855 mA·h·cm -3 Therefore, zinc-ion batteries have broad application prospects. As a new type of energy storage device that can replace lithium-ion batteries, zinc-ion batteries can be environmentally friendly, safe, and reduce battery manufacturing costs.

[0003] Zinc-ion batteries use an aqueous electrolyte, consisting of Zn. 2+ The zinc-ion battery consists of an ion storage positive electrode and a Zn metal negative electrode, exhibiting a high negative electrode capacity. During discharge and charging, Zn is reversibly stripped / deposited onto the negative electrode and reversibly inserted / extracted from the positive electrode, respectively. 2+ Zinc-ion batteries are used to store and release energy. They are inexpensive, use inexpensive materials, are easy to manufacture, and can operate in everyday environments, making them promising for large-scale energy storage applications. However, during charge-discharge cycles, uneven coating and peeling of zinc on the negative electrode surface easily leads to dendrite growth. Dendrite formation reduces coulombic efficiency (CE), and larger dendrites may puncture the separator, causing a short circuit. Dendrites have weak adhesion to the metal substrate and easily detach from the negative electrode, thus reducing its capacity. Furthermore, the hydrogen evolution reaction (HER) on the zinc surface causes the decomposition of water in the electrolyte, producing H₂. + It is reduced to H2, and the generated OH - The formation of a strongly alkaline environment generates byproducts such as Zn(OH)2 and ZnO, which not only corrode and passivate the surface of the negative electrode, but the generated gases may also lead to battery swelling and electrolyte leakage. These problems severely limit the performance of zinc metal negative electrodes. Summary of the Invention

[0004] To address the serious problems of dendrite growth and HER side reactions in aqueous zinc-ion batteries, this invention provides a method for modifying the interface of the zinc anode in aqueous zinc-ion batteries. This invention reduces dendrite growth on the anode surface and lowers HER side reactions by etching the zinc foil surface with phosphoric acid to expose the (002) crystal plane of the zinc foil surface, while simultaneously coating it with nano-silver particles. This method improves the cycle time and coulombic efficiency of the battery.

[0005] Technical solution: A method for modifying the interface of a metallic zinc anode in an aqueous zinc-ion battery, the method comprising the following steps:

[0006] S1. Immerse the zinc foil in a phosphoric acid solution for a period of time to etch it, then remove and dry it.

[0007] S2. Dissolve glucose and PVP in water to prepare solution A; dissolve silver nitrate in water to prepare solution B;

[0008] S3. Solution B is added dropwise to heated solution A to obtain a black suspension;

[0009] S4. Weigh PVP and PAM and add them to a container containing black suspension. After sealing, stir on a stirring table for a period of time to obtain a gel-like coating material.

[0010] S5. Apply the gel-like coating material onto the dried zinc foil, and after natural drying, obtain the metallic zinc anode of the aqueous zinc-ion battery.

[0011] Preferably, in S1: the concentration of the phosphoric acid solution is (0.1-1) mol / L, preferably 0.5 mol / L; the etching time is (0.5-3) min, preferably 1 min; the zinc foil is 8 cm long and 4 cm wide; and the drying temperature is 60℃.

[0012] Preferably, in S2: in solution A, the concentration of glucose is 50 g / L and the concentration of PVP is 15 g / L; in solution B, the concentration of silver nitrate is 20 g / L. Solution A is adjusted to pH 11 using NaOH.

[0013] Preferably, the specific operation of S3 is as follows: Under constant temperature water bath conditions, solution A is heated to 70°C in a water bath, and then solution B is added to solution A at a rate of 30 drops / min. After the addition is complete, the mixture is stirred for 15 minutes to obtain a black suspension.

[0014] Preferably, in S4, the mass ratio of PVP, PAM, and black suspension is 5g:0.5g:3mL; and the stirring time is 12h.

[0015] The aqueous zinc-ion battery anode prepared by the method of this invention can be used to assemble zinc-ion batteries.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] (1) This invention successfully exposed the (002) crystal plane of a zinc sheet by performing phosphoric acid etching. The modified interface can accelerate the growth of Zn. 2+ Diffusion kinetics, ensuring Zn 2+ Uniform nucleation and efficient deposition, while suppressing hydrogen release, reducing polarization and hydrogen evolution corrosion side reactions, effectively improve the cycle performance of the battery.

[0018] (2) The Ag coating of this invention can effectively improve the conductivity of zinc-ion batteries and reduce the polarization voltage. At the same time, due to the presence of binders such as PVP and PAM, the zinc foil surface is isolated from the electrolyte, which can effectively reduce the formation of dendrites, inhibit the hydrogen evolution reaction, effectively improve the battery life, and make the battery more stable.

[0019] (3) The preparation process adopted in this invention is highly clean and environmentally friendly, and does not use any easily manufactured toxic or explosive chemicals throughout the process, which significantly improves the safety and reliability of the operation process and effectively avoids potential harm to the environment and personnel. The process is simple, the conditions are mild, the equipment requirements are low, and it has good scalability, which can meet the needs of large-scale industrial production. In practical applications, it has shown important promotional value and broad market prospects.

[0020] (4) The zinc-ion battery prepared in this invention operates at 1 mA·cm⁻¹ -2 Current density and 1 mA·h·cm -2 Under the given areal capacity conditions, it can stably cycle for more than 2400 hours, and its cycle life is far superior to that of bare zinc electrode materials. It exhibits excellent electrochemical stability and long-term cycling capability, and has very promising prospects for practical application. Attached Figure Description

[0021] Figure 1 Scanning electron microscope (SEM) image of the phosphoric acid etching that exposed the (002) crystal plane prepared in Example 1.

[0022] Figure 2 The image shows a scanning electron microscope (SEM) image of the PA / Ag@Zn electrode prepared in Example 2.

[0023] Figure 3 The symmetrical cell assembled from the PA / Ag@Zn electrode prepared in Example 2 operates at 1 mA·cm⁻¹. -2 1mA·h·cm -2 A comparison of voltage-time curves of symmetrical cells assembled with bare zinc electrodes under the specified conditions.

[0024] Figure 4 The symmetrical cell assembled from the PA / Ag@Zn electrode prepared in Example 2 operates at 2 mA·cm⁻¹. -21mA·h·cm -2 A comparison of voltage-time curves of symmetrical cells assembled with bare zinc electrodes under the specified conditions.

[0025] Figure 5 This is a comparison chart of the rate performance of a symmetrical cell assembled with PA / Ag@Zn electrodes prepared in Example 3 and a symmetrical cell assembled with bare zinc electrodes.

[0026] Figure 6 The symmetrical cell assembled with the PA / Ag@Zn electrode prepared in Example 3 and the symmetrical cell assembled with the bare zinc electrode achieved a voltage of 5 mA·cm⁻¹. -2 1mA·h·cm -2 A comparison chart of impedance performance under different conditions. Detailed Implementation

[0027] The technical solution of the present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited to the embodiments described. The phosphoric acid solution used in the experiment was obtained from Shanghai Maclean Laboratory, with a concentration of 1 mol / L.

[0028] Example 1:

[0029] (1) Prepare phosphoric acid solution: Prepare phosphoric acid solution to 0.5 mol / L and pour phosphoric acid into petri dish; at the same time, cut zinc sheet into zinc foil with a length of 8 cm and a width of 4 cm.

[0030] (2) Soak the zinc foil in a 0.5 mol / L phosphoric acid solution for 1 min.

[0031] Figure 1 This is a SEM image of the zinc foil after phosphoric acid etching in this embodiment.

[0032] Example 2:

[0033] (1) Prepare phosphoric acid solution: Prepare phosphoric acid solution to 0.5 mol / L and pour phosphoric acid into petri dish; at the same time, cut zinc sheet into zinc foil with a length of 8 cm and a width of 4 cm.

[0034] (2) Soak the zinc foil in a 0.5 mol / L phosphoric acid solution for 1 min to expose the (002) crystal plane, then remove it with tweezers and dry it in an oven at 60°C.

[0035] (3) When drying the zinc foil, take 5g of glucose and 1.5g of PVP (K30) and dissolve them in water to prepare a 100mL aqueous solution, which is labeled as solution A. Adjust the pH to 11 with NaOH solution. Weigh 2g of silver nitrate (AgNO3) and dissolve it in water to prepare another 100mL aqueous solution, which is labeled as solution B.

[0036] (4) Under constant temperature water bath conditions, solution A is heated to 70°C in a water bath, and then solution B is added to solution A at a rate of 30 drops / min. After the addition is complete, the mixture is stirred for 15 minutes to obtain a black suspension.

[0037] (5) Take out 3 mL of black suspension and pour it into a small beaker. Add 5 mg PVP (polyvinylpyrrolidone K30) and 0.5 mg PAM (polyacrylamide) binder in a mass ratio of 10:1.

[0038] Seal with sealing film and stir on a mixing table for 12 hours to obtain a gel-like coating material.

[0039] (5) Use a scraper to evenly coat the prepared gel-like coating material onto the etched zinc foil, and let it dry naturally to obtain the PA / Ag@Zn electrode. Figure 2 The image shows a SEM image of PA / Ag@Zn prepared in Example 2.

[0040] (6) Assemble two PA / Ag@Zn electrodes into a battery pair, using a 2mol / L ZnSO4 solution as the electrolyte, and test its electrochemical performance.

[0041] Figure 3 The symmetrical cell assembled from the PA / Ag@Zn electrode prepared in Example 2 operates at 1 mA·cm⁻¹. -2 1mA·h·cm -2 A comparison of voltage-time curves of a symmetrical cell assembled with a bare zinc electrode under the specified conditions. Figure 3 As shown, the PA / Ag@Zn / / PA / Ag@Zn battery system, at 1mA·cm -2 1mA·h·cm -2 Under the test conditions, the cycle life reached 2400 hours, and the polarization voltage did not change abruptly over a long period of time, demonstrating high cycle stability.

[0042] Figure 4 The symmetrical cell assembled from the PA / Ag@Zn electrode prepared in Example 2 operates at 2 mA·cm⁻¹. -2 1mA·h·cm -2 A comparison of voltage-time curves of a symmetrical cell assembled with a bare zinc electrode under the specified conditions. Figure 4 As shown, the PA / Ag@Zn / / PA / Ag@Zn battery system, at 2mA·cm -2 1mA·h·cm -2 Under the test conditions, the cycle life reached 2100h, and the polarization voltage did not change abruptly over a long period of time, demonstrating high cycle stability.

[0043] Example 3:

[0044] The preparation steps were the same as in Example 2. Zinc foil was immersed in 0.5 mol / L phosphoric acid solution for 1 min, then removed and dried. 5 g glucose and 1.5 g PVP (K30) were prepared into 100 mL solution, and the pH was adjusted to 11. 2 g AgNO3 was prepared into 100 mL solution. AgNO3 was slowly added dropwise to the glucose solution at 70 °C to obtain a black suspension. 3 mL of the suspension was taken out and PVP and PAM binder were added at a ratio of 10:1. The mixture was stirred for 12 h to obtain a gel-like coating material. The prepared slurry was coated onto the etched zinc foil and dried to obtain the PA / Ag@Zn electrode.

[0045] Figure 5 This is a comparison chart of the rate performance of a symmetrical cell assembled with PA / Ag@Zn electrodes prepared in Example 3 and a symmetrical cell assembled with bare zinc electrodes.

[0046] A symmetrical battery was assembled using the two PA / Ag@Zn electrodes prepared in Example 3, with a 2 mol / L ZnSO4 solution as the electrolyte. Its electrochemical performance was tested, and the results are as follows: Figure 5 As shown, the performance of the PA / Ag@Zn / / PA / Ag@Zn battery system was not significantly affected by changes in current density, demonstrating its stability in complex environments.

[0047] A symmetrical battery was assembled using the two PA / Ag@Zn electrodes prepared in Example 3, with a 2 mol / L ZnSO4 solution as the electrolyte. Its electrochemical performance was tested, and the results are as follows: Figure 6 As shown, the PA / Ag@Zn / / PA / Ag@Zn battery system, at 5mA·cm -2 1mA·h·cm -2 Under the test conditions, it can be seen that compared with the symmetrical battery assembled with bare zinc electrodes, its resistance is significantly reduced, and it can still maintain a small resistance after 100 cycles, showing that its discharge power is significantly improved and its energy utilization is significantly improved.

[0048] Example 4:

[0049] Following the method of Example 2, but immersing zinc foil in phosphoric acid solutions of different concentrations for different times, PA / Ag@Zn electrodes were prepared. The PA / Ag@Zn electrodes prepared by immersion in phosphoric acid solutions of different concentrations for different times were observed under an optical microscope. Under controlled conditions, the phosphoric acid concentration of 0.5 mol / L and the etching time of 1 min selected in this invention were optimal.

[0050] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention.

Claims

1. A method for modifying the interface of a metallic zinc anode in an aqueous zinc-ion battery, characterized in that, The method includes the following steps: S1. Immerse the zinc foil in a phosphoric acid solution for a period of time to etch it, then remove and dry it. S2. Dissolve glucose and PVP in water to prepare solution A, and dissolve silver nitrate in water to prepare solution B; S3. Solution B is added dropwise to heated solution A to obtain a black suspension; S4. Weigh PVP and PAM and add them to a container containing black suspension. After sealing, stir on a stirring table for a period of time to obtain a gel-like coating material. S5. Apply the gel-like coating material onto the dried zinc foil and allow it to dry naturally to obtain the PA / Ag@Zn negative electrode.

2. The modification method according to claim 1, characterized in that, In S1: The concentration of the phosphoric acid solution was (0.1-1) mol / L, and the etching time was (0.5-3) min.

3. The modification method according to claim 2, characterized in that, In S1: The concentration of the phosphoric acid solution was 0.5 mol / L, and the etching time was 1 min.

4. The modification method according to claim 1, characterized in that, In S2: In solution A, the concentration of glucose is 50 g / L and the concentration of PVP is 15 g / L; in solution B, the concentration of silver nitrate is 20 g / L. Adjust the pH of solution A to 11 using NaOH.

5. The modification method according to claim 1, characterized in that, The specific operation of S3 is as follows: Under constant temperature water bath conditions, solution A is heated to 70°C in the water bath, and then solution B is added to solution A at a rate of 30 drops / min. After the addition is complete, the mixture is stirred for 15 minutes to obtain a black suspension.

6. The modification method according to claim 1, characterized in that, In S4: The mass ratio of PVP, PAM, and black suspension was 5 g: 0.5 g: 3 mL; the stirring time was 12 h.

Images