Preparation and application of tin-protected three-dimensional zinc metal negative electrode with high cycle stability

Abstract

This invention relates to the preparation and application of a tin-protected three-dimensional zinc metal anode with high cycle stability. It addresses the critical reaction interface problem in zinc anodes by constructing a uniform tin layer with a unique three-dimensional porous structure and zinc affinity on the zinc surface through simultaneous liquid-phase deposition. Compared with existing technologies, this invention utilizes a strategy of rapid modification of the zinc metal anode with Sn(OTf)₂, which has a positive impact on the performance testing of both symmetric and asymmetric batteries, resulting in superior long-cycle stability, higher capacity retention, and a smoother deposition surface. This provides a new design scheme for the fabrication of highly stable aqueous zinc-ion batteries.

Description

Technical Field

[0001] This invention belongs to the field of electrode material preparation technology, and relates to a tin-protected three-dimensional zinc metal anode with high cycle stability, as well as its preparation and application. Background Technology

[0002] In response to the growing demands of modern lifestyles, the development of safe and economical energy storage technologies has become an inevitable trend in modern society. Weakly acidic aqueous zinc-ion batteries are considered promising energy storage systems for the future, with applications in next-generation large-scale energy storage devices and biocompatible electronics. This is due to their safe and non-toxic aqueous electrolyte, and most importantly, the low cost and abundant resources of zinc. To date, zinc's high theoretical capacity (820 mAh g / g) has been a key factor in its development. -1 With its suitable redox potential (-0.76V vs SHE, standard hydrogen electrode), zinc metal anodes dominate in aqueous zinc-ion batteries. However, key issues such as the high chemical reactivity of zinc and the uncontrollable morphology of zinc electrodeposit during battery charging pose significant obstacles to the development of practical, weakly acidic aqueous zinc-ion batteries based on zinc metal anodes.

[0003] Uncontrolled interfacial heteroelectrodeposition on the surface of zinc metal anodes primarily stems from inhomogeneous nucleation and crystal growth during repeated peeling and electroplating processes. Since the electrode / electrolyte interface is the site of electrochemical reactions, rational interface engineering shows great potential for addressing the unstable physicochemical properties of zinc metal anodes. Constructing artificial solid electrolyte interfaces (ASMEs) is a crucial strategy for improving cycle stability and preventing electrochemical parasitic reactions. Although significant progress has been made in the design and application of ASMEs for zinc metal anodes, most reported synthesis strategies rely on complex, non-in-situ processes and introduce coupling with polyvinylidene fluoride (PVDF) with poor ionic conductivity. Unfortunately, little attention has been paid to the energy and time consumption during the synthesis of ASMEs for zinc metal anodes, which is as important as the function of the ASME. Therefore, developing energy-efficient and time-saving methods to construct suitable ASMEs on zinc metal anodes is a direct approach to achieving cost-effective aqueous zinc-ion batteries. Furthermore, the precise design of ASMEs with high zinc affinity and uniform crystal orientation is equally crucial for ensuring the electrochemical reversibility of zinc metal anodes. Zinc-loving metal layers (such as tin and indium) constructed through spontaneous electrodisplacement reactions can effectively reduce the nucleation barrier, thereby promoting uniform growth of metallic zinc. However, these traditional two-dimensional metallic artificial solid electrolyte interfaces cannot adapt to volume expansion, making it difficult to maintain high stability during continuous zinc deposition.

[0004] For example, Chinese patent CN112736238A discloses a tin-zinc anode material for zinc metal batteries / capacitors and its preparation method, which is prepared by the following steps: Step 1: Polishing ordinary zinc sheets to remove the passivation layer; Step 2: Preparing a tin salt solution; dissolving 1 mol of tin salt in deionized water, and adding concentrated hydrochloric acid dropwise until the solution is just clear and transparent before adjusting the volume to 1000 mL; Step 3: Immersing the zinc sheet in the above homogeneous solution at room temperature and pressure for 30 seconds; after the reaction is completed, the tin-zinc anode material for zinc metal batteries / capacitors is obtained. This preparation method has the following three shortcomings: 1. The steps are cumbersome, requiring polishing of the zinc sheet to remove the passivation layer; 2. The amount of tin salt used is very large; 3. The electrode coating prepared by this method lacks a three-dimensional porous structure. Summary of the Invention

[0005] The purpose of this invention is to provide a tin-protected three-dimensional zinc metal anode with high cycle stability, as well as its preparation and application.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] One of the technical solutions of the present invention provides a method for preparing a tin-protected three-dimensional zinc metal anode with high cycle stability, comprising the following steps:

[0008] (1) Weigh Sn(OTf)2 and dissolve it in deionized water to prepare Sn(OTf)2 solution;

[0009] (2) Take the pretreated Zn sheet and immerse it in the Sn(OTf)2 solution in step (1). Then take it out, clean and dry it to obtain Sn@3D-Zn anode, which is the target product.

[0010] Furthermore, in step (1), the concentration of the Sn(OTf)2 solution is 0.01–0.05 mol / L.

[0011] Furthermore, in step (1), the concentration of the Sn(OTf)2 solution is 0.03 mol / L.

[0012] Furthermore, in step (2), the Zn wafer pretreatment process is as follows: first, use alcohol ultrasonic cleaning to remove any organic impurities that may exist on the surface, and then dry it in a vacuum drying oven at 60°C.

[0013] Furthermore, in step (2), the soaking is carried out at room temperature.

[0014] Furthermore, in step (2), the soaking time is 5-30 seconds.

[0015] Furthermore, in step (2), the soaking time is 10 seconds.

[0016] The working principle of the tin-protected three-dimensional zinc metal anode of the present invention is as follows:

[0017] 1. Tin trifluoromethanesulfonate (Sn(OTf)2) can produce H+ in aqueous solution through hydrolysis. + The specific equation is as follows: Sn(OTf)₂ + H₂O = Sn(OH)OTf + HOTf. Sn(OTf)₂, as a strong nucleophilic Lewis acid, can rapidly remove the oxide layer from the surface of commercial zinc foil in its aqueous solution. Simultaneously, trifluoromethanesulfonate (OTf) - The radius of ) is relatively large, which allows H to + It can perform deep etching on the same zinc foil surface to form a three-dimensional metallic zinc matrix, marked as 3D-Zn.

[0018] 2. Because the reduction potential of metallic tin is higher than that of metallic zinc (-0.14V and -0.76V respectively relative to the standard hydrogen electrode), the metallic tin interface layer can be generated on the surface of zinc foil through the following chemical process: Zn + Sn(OTf)2 → Sn + Zn(OTf)2.

[0019] The second technical solution of the present invention provides a tin-protected three-dimensional zinc metal anode with high cycle stability, which is prepared by any of the preparation methods described above.

[0020] The third technical solution of the present invention provides an application of a tin-protected three-dimensional zinc metal anode with high cycle stability, which is used to prepare aqueous zinc-ion batteries, zinc symmetric batteries or zinc-copper asymmetric batteries.

[0021] Furthermore, the specific preparation process of the aqueous zinc-ion battery is as follows:

[0022] (A-1) Weigh V2O5 and dissolve it in deionized water at room temperature by stirring. Then add aniline and add hydrochloric acid to adjust the pH of the solution to 3 to obtain a mixed solution.

[0023] (A-2) The mixed solution obtained in step (A-1) was transferred to a high-pressure hydrothermal reactor, heated to 120°C and reacted for 24 hours. Then it was cooled to room temperature and the reaction product was collected. After washing and drying, PANI-V2O5 was obtained.

[0024] (A-3) Weigh the PANI-V2O5, acetylene black and polyvinylidene fluoride obtained in step (A-2), grind and mix them, then add N-methylpyrrolidone dropwise, and continue mixing and stirring to obtain a slurry;

[0025] (A-4) The slurry obtained in step (A-3) is dropped onto carbon cloth and then dried to obtain the positive electrode of an aqueous zinc-ion battery for later use;

[0026] (A-5) Cut the glass fiber diaphragm to the designed size and prepare a ZnSO4 aqueous solution as an electrolyte for later use;

[0027] (A-6) The battery casing is of type CR2032. It is stacked in the following order: negative electrode casing → Sn@3D-Zn negative electrode → glass fiber separator → PANI-V2O5 → gasket → spring sheet → positive electrode casing. Then, it is sealed using a battery sealing machine to prepare an aqueous zinc-ion battery.

[0028] Furthermore, the specific fabrication process of the zinc symmetric battery is as follows:

[0029] (B-1) Cut the glass fiber diaphragm to the designed size and prepare a ZnSO4 aqueous solution as an electrolyte for later use;

[0030] (B-2) The battery casing is of type CR2032. It is stacked in the following order: negative electrode casing → Sn@3D-Zn → glass fiber separator → Sn@3D-Zn → gasket → spring sheet → positive electrode casing. Then, it is sealed using a battery sealing machine to obtain a zinc symmetric battery.

[0031] Furthermore, the specific fabrication process of the zinc-copper asymmetric battery is as follows:

[0032] (C-1) Cut the glass fiber diaphragm to the designed size and prepare a ZnSO4 aqueous solution as an electrolyte for later use;

[0033] (C-2) Weigh out ZnSO4·7H2O, NaCl and H3BO3 and dissolve them in water to obtain a mixed solution;

[0034] (C-3) A three-electrode system is prepared using Cu foil from step (C-1) as the working electrode, Pt sheet as the counter electrode, saturated calomel electrode as the reference electrode, and mixed solution from step (C-2) as the electrolyte.

[0035] (C-4) Utilizing -3mA cm -2 A constant current is applied to deposit Zn onto the Cu foil in the three-electrode system constructed in step (C-3) to obtain a Zn@Cu electrode sheet;

[0036] (C-5) The Zn@Cu electrode sheet obtained in step (C-4) is immersed in Sn(OTf)2 aqueous solution, taken out, washed and dried to obtain Sn@Cu;

[0037] (C-6) The battery casing is made of CR2032 type. The casing is stacked in the following order: negative electrode shell → Sn@3D-Zn → glass fiber separator → Sn@Cu → gasket → spring sheet → positive electrode shell. Then, it is sealed using a battery sealing machine to obtain a zinc-copper asymmetric battery.

[0038] This invention utilizes electrodeposition in the preparation of Sn@Cu electrodes, instead of the traditional plating method using PVDF and NMP slurry. This in-situ preparation process maximizes the reproduction of the three-dimensional plating structure of the Sn@3D-Zn anode, thus improving the reliability of test data.

[0039] Compared with the prior art, the present invention has the following advantages:

[0040] (1) This invention is the first to utilize a low-concentration (0.03M) Sn(OTf)₂ aqueous solution to simultaneously grow a tin metal protective layer—Sn@3D-Zn—on the surface of commercial zinc foil, forming a three-dimensional porous structure. This synthesis method can be carried out at room temperature and has an extremely short preparation time, requiring only 10 seconds to complete the entire process. While significantly reducing energy consumption and time costs, it also enables large-scale production, meeting the requirements of next-generation low-cost aqueous zinc-ion batteries.

[0041] (2) The Sn@3D-Zn anode can effectively prevent electrochemical parasitic reactions and has good corrosion resistance. More importantly, the Sn@3D-Zn anode can effectively reduce Zn... 2+ The energy required for deposition is reduced, and the planar deposition of metallic zinc is guided to suppress zinc dendrite growth. Furthermore, the three-dimensional zinc matrix effectively mitigates volume changes during repeated zinc stripping and deposition. The performance of the assembled Sn@3D-Zn / / PANI-V2O5 battery demonstrates that Sn@3D-Zn can effectively improve the lifespan of aqueous zinc-ion batteries, providing a pathway for promoting the practical application of aqueous zinc-ion batteries. Attached Figure Description

[0042] Figure 1a XRD pattern of Sn@3D-Zn;

[0043] Figure 1b SEM images of Sn@3D-Zn

[0044] Figure 1c Optical photographs of Sn@3D-Zn with the initial zinc foil;

[0045] Figure 1d Optical images prepared for large-area Sn@3D-Zn fabrication;

[0046] Figure 2a SEM image of a standard zinc sheet;

[0047] Figure 2b SEM image of 0.01-Sn@3D-Zn;

[0048] Figure 2c SEM image of 0.05-Sn@3D-Zn;

[0049] Figure 2d SEM image of Sn@3D-Zn-5;

[0050] Figure 2e SEM image of Sn@3D-Zn-20;

[0051] Figure 2f SEM image of Sn@3D-Zn-30;

[0052] Figure 2g Cyclic voltammetry curves for ordinary zinc sheet, Sn@3D-Zn, and Sn@3D-Zn-5, 20, and 30;

[0053] Figure 2h Comparison of nucleation overpotentials for ordinary zinc sheet, Sn@3D-Zn, and Sn@3D-Zn-5, 20, and 30;

[0054] Figure 3a Corrosion curves of Sn@3D-Zn and ordinary zinc sheets;

[0055] Figure 3b Linear scanning voltammetric curves of Sn@3D-Zn and ordinary zinc sheets;

[0056] Figure 3c The Tafel slope of Sn@3D-Zn and ordinary zinc sheet;

[0057] Figure 4a Coulombic efficiency of Zn / / Cu asymmetric cell and Sn@3D-Zn / / Sn@Cu asymmetric cell;

[0058] Figure 4b Voltage-capacity curves for Sn@3D-Zn / / Sn@Cu asymmetric cells;

[0059] Figure 4c The voltage-capacity curve of a Zn / / Cu asymmetric cell;

[0060] Figure 4d 0.5mA cm -2 0.25mAh cm -2 Long-cycle performance of symmetric cells under test conditions;

[0061] Figure 4e 0.5mA cm -2 0.25mAh cm -2 SEM images of Sn@3D-Zn after 200 cycles under test conditions;

[0062] Figure 4f 0.5mA cm -20.25mAh cm -2 SEM images of ordinary zinc sheets after 200 cycles under test conditions;

[0063] Figure 4g 2.0mA cm -2 0.5mAh cm -2 Long-cycle performance of symmetric cells under test conditions;

[0064] Figure 4h 5.0mA cm -2 1.0mAh cm -2 Long-cycle performance of symmetric cells under test conditions;

[0065] Figure 4i Rate performance of Sn@3D-Zn symmetric cells and ordinary zinc symmetric cells;

[0066] Figure 4j Voltage polarization of Sn@3D-Zn symmetric cells and ordinary zinc symmetric cells at different current densities;

[0067] Figure 5a SEM image of PANI-V2O5;

[0068] Figure 5b The XRD pattern of PANI-V2O5;

[0069] Figure 5c Cyclic voltammetry curves of aqueous Sn@3D-Zn / / PANI-V2O5 batteries;

[0070] Figure 5d Electrochemical impedance spectroscopy (EIS) of an aqueous Sn@3D-Zn / / PANI-V2O5 battery;

[0071] Figure 5e For aqueous Sn@3D-Zn / / PANI-V2O5 batteries at 0.48 A g -1 Long-term stability under these conditions;

[0072] Figure 5f For aqueous Sn@3D-Zn / / PANI-V2O5 batteries at 0.48 A g -1 Constant current charge-discharge curves for a specific number of cycles;

[0073] Figure 5g For aqueous Zn / / PANI-V2O5 batteries at 0.48 A g -1 Constant current charge-discharge curves for a specific number of cycles;

[0074] Figure 5h For aqueous Sn@3D-Zn / / PANI-V2O5 batteries at 0.96 A g-1 Long-term stability under these conditions;

[0075] Figure 5i For aqueous Sn@3D-Zn / / PANI-V2O5 batteries at 0.96 A g -1 Constant current charge-discharge curves for a specific number of cycles;

[0076] Figure 5j For aqueous Zn / / PANI-V2O5 batteries at 0.96 A g -1 Constant current charge-discharge curves for a specific number of cycles;

[0077] Figure 5k SEM image of Sn@3D-Zn negative electrode after 100 cycles;

[0078] Figure 5l SEM image of a standard zinc negative electrode after 100 cycles;

[0079] Figure 6a The image shows the SEM image of the Zn slices in Comparative Example 1 after immersion in 0.03M SnCl4 for 10 seconds.

[0080] Figure 6b This is an optical photograph of the Zn sheet in Comparative Example 1 after immersion in 0.03M SnCl4 for 10 seconds;

[0081] Figure 6c SEM images of Zn slices after immersion in 0.03M SnCl2 for 10 seconds;

[0082] Figure 6d This is an optical photograph of a Zn sheet after immersion in 0.03M SnCl2 for 10 seconds. Detailed Implementation

[0083] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0084] The performance characterization methods used in the following embodiments are as follows:

[0085] Material phase characterization

[0086] The morphology and surface elemental distribution of the material were characterized using a Hitachi S-4800 scanning electron microscope (SEM) equipped with an energy-dispersive X-ray spectrometer. X-ray diffraction (XRD) patterns were obtained using Cu Kα rays from a Bruker D8 Advance diffractometer.

[0087] Electrochemical performance characterization of materials

[0088] The positive electrode of the battery under test was prepared by stirring the active material PANI-V2O5, the additive acetylene black, and the binder polyvinylidene fluoride in a mass ratio of 8:1:1 under N-methylpyrrolidone to form a slurry. The slurry was then coated onto a carbon cloth current collector. Specific operating procedures are detailed in Technical Scheme 5. The mass of active material on all electrode sheets was measured using an electronic balance with an accuracy of 0.01 mg. The mass of active material in the PANI-V2O5 battery positive electrode was approximately 1.6 mg / cm³. -2 Linear sweep voltammetry (LSV) curves and corrosion currents of Sn@3D-Zn and ordinary zinc sheets were measured using a three-electrode system under standard atmospheric conditions. A Pt electrode and a saturated calomel electrode were used as the counter and reference electrodes, respectively, and a 2.0 M sodium sulfate solution (Na₂SO₄) was used as the electrolyte. The three-electrode system tests and the cyclic voltammetry curves of the aqueous zinc-ion coin cell were performed at room temperature on a CHI 760E electrochemical workstation. Furthermore, the coulombic efficiency of the zinc-copper asymmetric cell, the rate performance and long-cycle testing of the zinc symmetric cell, and the long-cycle testing and galvanostatic charge-discharge curves of the aqueous zinc-ion coin cell were all performed at room temperature on a LAND testing system. For electrochemical impedance spectroscopy (EIS) measurements, an AC amplitude of 10 mV was applied to the aqueous zinc-ion coin cell in the range of 100 kHz to 10 mHz.

[0089] In the following embodiments, unless otherwise specified, the raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.

[0090] Example 1:

[0091] Preparation of Sn@3D-Zn anode:

[0092] (1) Weigh 125 mg of Sn(OTf)2 and dissolve it in 10 mL of deionized water at room temperature;

[0093] (2) Cut Zn sheets with a diameter of 14 mm, and clean the surface with alcohol and ultrasonic cleaning for any organic impurities that may be present. Then dry them in a vacuum drying oven at 60°C.

[0094] (3) Immerse the dried Zn sheet in step (2) in the 0.03M Sn(OTf)2 solution prepared in step (1), take it out after soaking for 10 seconds, then wash it with deionized water and dry it in a vacuum drying oven at 60°C.

[0095] The Sn@3D-Zn anode prepared above was used to prepare aqueous zinc-ion batteries, zinc-symmetric batteries, or zinc-copper asymmetric batteries, respectively. The specific processes are as follows:

[0096] Preparation of aqueous zinc-ion batteries:

[0097] (1) Weigh 0.36g V2O5 and dissolve it in 60mL of deionized water at room temperature by stirring. Label it as solution A.

[0098] (2) Measure 60 μL of aniline and add it to solution A, then label it as solution B;

[0099] (3) Gradually add 3M hydrochloric acid to solution B, gradually adjust the pH of solution B to about 3, and label it as solution C;

[0100] (4) After stirring solution C for 20 minutes, transfer it to a high-pressure hydrothermal reactor with a 100 mL polytetrafluoroethylene liner, heat it to 120 °C and keep it there for 24 hours.

[0101] (5) After the hydrothermal reactor cools to room temperature, the product after hydrothermal treatment is collected by centrifugation and washed three times with deionized water and anhydrous ethanol respectively. It is then dried overnight in a vacuum drying oven at 60°C for later use. The sample is labeled as PANI-V2O5.

[0102] (6) Weigh 400mg of PANI-V2O5, 50mg of acetylene black and 50mg of polyvinylidene fluoride, and grind and mix them thoroughly in a mortar.

[0103] (7) Add 200 μL of N-methylpyrrolidone to the mixture obtained after grinding in (6) and continue mixing and stirring for 12 hours;

[0104] (8) Using a pipette, drop 40 μL of the slurry obtained in (7) onto a 1×1 cm plate. 2 The carbon cloth was then placed on it and dried in a vacuum drying oven at 80°C for 12 hours to be used as the positive electrode for aqueous zinc-ion batteries.

[0105] (9) Cut a 14mm glass fiber diaphragm and prepare a 2M ZnSO4 aqueous solution as an electrolyte for later use;

[0106] (10) The battery casing is of type CR2032. It is stacked in the following order: negative electrode casing → Sn@3D-Zn → glass fiber separator → PANI-V2O5 → gasket → spring sheet → positive electrode casing. Then, it is sealed using a battery sealing machine. Note: When stacking to the glass fiber separator, add 120μL of 2M ZnSO4 aqueous solution as electrolyte.

[0107] Preparation of zinc symmetric cells

[0108] (1) Cut a 14mm glass fiber diaphragm and prepare a 2M ZnSO4 aqueous solution as an electrolyte for later use;

[0109] (2) The battery casing is of type CR2032. It is stacked in the following order: negative electrode casing → Sn@3D-Zn → glass fiber separator → Sn@3D-Zn → gasket → spring clip → positive electrode casing. Then, it is sealed using a battery sealing machine. Note: When stacking to the glass fiber separator, add 120 μL of 2M ZnSO4 aqueous solution as the electrolyte.

[0110] Preparation of zinc-copper asymmetric cells

[0111] (1) Cut a 14mm glass fiber diaphragm and Cu foil, and prepare a 2M ZnSO4 aqueous solution as an electrolyte for later use;

[0112] (2) Weigh 37.3g of ZnSO4·7H2O, 1.1g of NaCl and 1.0g of H3BO3, and dissolve them in 100mL of water;

[0113] (3) In step (1), the Cu foil is the working electrode, the Pt sheet is the counter electrode, the saturated calomel electrode is the reference electrode, and the solution in step (2) is the electrolyte to prepare a three-electrode system.

[0114] (4) Using -3mA cm -2 A constant current is applied to the Cu foil in step (3) to deposit Zn, and the process is maintained for 1 hour.

[0115] (5) After cleaning and drying the Zn@Cu electrode obtained in step (4), immerse it in the 0.03M Sn(OTf)2 aqueous solution prepared in Scheme 1 for 10s and then take it out. Then wash it with deionized water and dry it in a vacuum drying oven at 60℃. The sample is labeled as Sn@Cu.

[0116] (6) The battery casing is of type CR2032. It is stacked in the following order: negative electrode casing → Sn@3D-Zn → glass fiber separator → Sn@Cu → gasket → spring sheet → positive electrode casing. Then, it is sealed using a battery sealing machine. Note: When stacking to the glass fiber separator, add 120μL of 2M ZnSO4 aqueous solution as electrolyte.

[0117] Phase characterization of Sn@3D-Zn from Example 1:

[0118] Figure 1a The XRD pattern of Sn@3D-Zn is shown, where the diffraction peaks at 36.2°, 39.0°, and 43.2° correspond to the (002), (100), and (101) crystal planes of metallic Zn, respectively (PDF#04-0831). New peaks at 30.6° and 32.0° correspond to the (200) and (101) crystal planes of metallic Sn, respectively (PDF#04-0673). The XRD pattern confirms that a tin protective layer has been successfully grown on ordinary zinc foil. To further determine the surface morphology of Sn@3D-Zn, we observed it using a scanning electron microscope. Figure 1b As shown, in Example 1, the zinc foil surface has been etched to form a highly porous state, and the surface has been uniformly covered with metallic tin. Figure 1c Optical photographs of the initial zinc foil and the Sn@Zn-3D obtained in Example 1 are shown, showing the color change from the initial silvery-white to gray. Furthermore, Figure 1d This demonstrates the feasibility of large-area preparation of Sn@3D-Zn based on the process described in Example 1.

[0119] Determination of optimal preparation conditions for Sn@3D-Zn

[0120] Figure 2a This demonstrates the relatively smooth initial surface morphology of a typical zinc sheet. Figure 2b and Figure 2c The surface morphology of zinc sheets prepared by immersion in 0.01M Sn(OTf)₂ aqueous solution and 0.05M Sn(OTf)₂ aqueous solution are shown respectively. Depending on the solution concentration, the obtained samples are designated as Sn@3D-Zn-0.01 and Sn@3D-Zn-0.05, respectively. This is in contrast to the case prepared with 0.03M Sn(OTf)₂ aqueous solution (…). Figure 1b The Sn@3D-Zn-0.01 etching produces fewer and smaller pores; while the porous structure of Sn@3D-Zn-0.05 is filled due to the excessive growth of Sn crystals, losing the advantages of the original three-dimensional zinc matrix structure. Therefore, the optimal Sn(OTf)2 aqueous solution concentration for Sn@3D-Zn preparation is determined to be 0.03M.

[0121] To further determine the optimal preparation time, this invention designed different soaking times of 5s, 10s, 20s and 30s based on orthogonal experiments. According to the different soaking times, the obtained samples were recorded as Sn-3D@Zn-5, Sn-3D@Zn-10 (i.e. Example 1), Sn-3D@Zn-20 and Sn-3D@Zn-30, respectively. Figure 2d-f shows the morphology of the zinc sheet surface after different immersion times. The Sn-3D@Zn-5 sheet immersed for 5 seconds already showed a relatively large number of porous structures on its surface; however, due to the shorter immersion time, the tin crystals formed on its surface were smaller. Figure 2d As the immersion time increased to 20 seconds, the tin crystals on the Sn-3D@Zn-20 surface continued to increase in size and began to show a tendency to cover the porous structure, such as... Figure 2e As shown. After immersion time reached 30 seconds, tin crystals almost completely covered the porous structure of the zinc sheet. Figure 2f Subsequently, through Figure 2g and Figure 2h Electrochemical tests demonstrated the advantages of Sn@3D-Zn's unique metallic tin-protected three-dimensional zinc matrix structure. The electroactive surface area of ​​the zinc electrode is one of the decisive factors in electrochemical performance, due to... Figure 2g The current in the cyclic voltammetry curve is generated by the redox reaction of zinc; therefore, the estimated specific surface area can be considered as the number of corresponding electrochemical active sites. The peak current (i) in the cyclic voltammetry curve... p This can be used to estimate the electroactive surface area (A) using the Delahay equation. e ): i p =3.67×10 5 n 3 / 2 A e cD 1 / 2 v 1 / 2 Where i p It is the peak current (mA), n is the number of electrons in the reaction (2), A e Electrochemically active surface area (cm²) 2 c is Zn 2+ volume concentration (2×10) -3 mol cm -3 D is Zn 2+ diffusion coefficient (1×10) -10 cm 2 s -1 ), and scan rate v (1mV s) -1 Comparing the cyclic voltammetry curves for different soaking times, except for i p Except for the values ​​mentioned above, all other values ​​remain the same. For example... Figure 2g As shown, Sn@3D-Zn immersed in 0.03M Sn(OTf)2 aqueous solution for 10s has the highest peak current (49.1mA); therefore, Sn@3D-Zn also has the highest electroactive surface area. Figure 2h The nucleation overpotential in the data further confirms the above results. Sn@3D-Zn has the lowest nucleation overpotential (25.4 mV), indicating that Sn@3D-Zn has more nucleation sites and effectively reduces Zn. 2+Energy barrier of deposition.

[0122] Corrosion resistance of Sn@3D-Zn (i.e., the sample prepared in Example 1)

[0123] Corrosion resistance is a fundamental requirement for achieving long cycle life in zinc metal anodes. Generally, a higher corrosion potential indicates a lower tendency for corrosion reactions (such as passivation caused by hydrogen evolution and dissolved oxygen), while a lower corrosion current density indicates a lower corrosion rate. Compared to ordinary zinc sheets, the corrosion potential of Sn@3D-Zn increases from -1.036V to -1.028V, with a corresponding increase in corrosion current density from 4.48 mA / cm². -2 Reduced to 3.42 mA cm -2 ( Figure 3a This confirms that the self-corrosion of the zinc metal anode was effectively suppressed by the tin protective layer. In the electrochemical process, the onset of the hydrogen evolution reaction can be determined from the hydrogen evolution initiation potential of its linear sweep voltammetry curve. To verify the suppression of the hydrogen evolution side reaction by the Sn@3D-Zn electrode, the linear sweep voltammetry curves of Sn@3D-Zn and ordinary zinc sheets were tested in 2M Na2SO4 electrolyte at a scan rate of 5 mV s. -1 .like Figure 3b As shown, the Sn@3D-Zn electrode consistently exhibits a lower H2 evolution current density between -1.1V and -2.1V, and the onset potential of the hydrogen evolution reaction (-1.93V vs. SCE) is higher than that of a conventional zinc electrode (-1.80V vs. SCE). Furthermore, Figure 3c The linear scanning voltammetric curve fitting of ordinary zinc sheet showed that the corresponding Tafel slope was much smaller than that of Sn@3D-Zn(355.8 vs 571.9 mVdec). -1 This fully demonstrates that the Sn@3D-Zn electrode has an excellent ability to inhibit water decomposition.

[0124] Sn@3D-Zn (i.e., the sample prepared in Example 1) guides Zn 2+ Stable deposition

[0125] The electrochemical performance of Sn@3D-Zn was further evaluated using zinc-symmetric and zinc-copper asymmetric cells. The coulombic efficiency of the Zn / / Cu asymmetric cell reflects the reversibility of zinc plating and stripping during long-term cycling. Measurements were performed using two different copper foils (ordinary copper foil and tin-plated copper foil) under test conditions of 0.5 mA cm⁻¹. -2 The current density and 0.25 mA h cm -2 The surface capacity. For example... Figure 4aAs shown, conventional Zn / / Cu asymmetric cells exhibit poor cycle life, with significant fluctuations in coulombic efficiency after 500 cycles, primarily due to zinc dendrite growth. The uneven zinc plating and stripping process, caused by the "tip effect" of zinc ion deposition, inevitably leads to the formation and growth of zinc dendrites, eventually causing short-circuit failure as the internal dendrites pierce the separator. However, using Sn@Cu as the electrode effectively avoids the short-circuit problem of Zn / / Cu asymmetric cells. The Sn@3D-Zn / / Sn@Cu asymmetric cell maintains an average coulombic efficiency of 99.1% over more than 1000 cycles. Figure 4b and Figure 4c The voltage-capacity curves of Zn / / Cu asymmetric cells and Sn@3D-Zn / / Sn@Cu asymmetric cells at a specific number of cycles are shown. The voltage polarization of the Sn@3D-Zn / / Sn@Cu cell is consistently lower than that of the Zn / / Cu asymmetric cell and remains stable during long-cycle testing. In contrast, the voltage polarization of the Zn / / Cu asymmetric cell increases continuously with the number of cycles and suddenly increases just before the cell fails.

[0126] The stability of zinc metal anodes is an important indicator for determining their performance. This invention studies this using a classic symmetrical battery long-cycle method. Next, at 0.5 mA cm⁻¹... -2 The current density and 0.25 mA h cm -2 At the areal capacity, long-term constant current cycling performance tests were conducted on the zinc symmetric cell. Impressively, as... Figure 4d As shown, an ultra-long cycle life of 4000 hours was achieved using a symmetric cell with Sn@3D-Zn. Figure 4e and Figure 4f The surface morphology evolution of the Sn@3D-Zn electrode and the ordinary zinc electrode after continuous electroplating and stripping visually demonstrates the role of the metallic tin protective layer and the three-dimensional metallic zinc substrate in suppressing zinc dendrite growth and alleviating electrode surface passivation. After 200 cycles, the SEM image of the ordinary zinc electrode (…) Figure 4e This indicates that its surface is covered with zinc dendrites and corrosion pits, and some glass fibers from the diaphragm can be observed within the zinc dendrites. Compared to... Figure 4f The Sn@3D-Zn electrode surface remained smooth, indicating that the tin protective layer and the three-dimensional zinc substrate effectively guided the smooth deposition of zinc ions. When the test current density and deposition surface capacity were increased to 2 mA cm⁻¹, the surface area remained consistent. -2 0.5mA h cm -2 ( Figure 4g ) and 5A cm -2 1.0mAh cm -2 ( Figure 4hWhen using Sn@3D-Zn, the zinc symmetric cell consistently maintains a cycle life superior to that of ordinary zinc sheets. Figure 4i The rate performance of Sn@3D-Zn symmetric cells and ordinary zinc symmetric cells was demonstrated when the current density changed from 0.25, 0.5, 1.0, 2.0 to 4.0 mA cm⁻¹. -2 At this time, the voltage polarization of Sn@3D-Zn remains stable and lower than that of zinc symmetric cells. Specific voltage polarization values ​​are as follows: Figure 4j As shown, the rapid synthesis of Sn(OTf)2 effectively extended the lifespan of the zinc metal anode by combining a metallic Sn protective layer with a three-dimensional zinc substrate. The ultra-long cycle life and high stability of the zinc symmetric battery assembled using Sn@3D-Zn strongly demonstrate the effectiveness of this strategy.

[0127] Practical application of Sn@3D-Zn (i.e., the sample prepared in Example 1) in aqueous zinc-ion batteries

[0128] To test the performance of Sn@3D-Zn negative electrode in rechargeable aqueous zinc-ion batteries, this invention uses 2M ZnSO4 solution as electrolyte and PANI-V2O5 as active material for assembling and testing zinc-ion batteries. Figure 5a and Figure 5b The morphology and XRD pattern of PANI-V2O5 are shown respectively. Figure 5c The two pairs of oxidation / reduction peaks represent V during discharge / charge, respectively. 3+ / V 4+ and V 4+ / V 5+ Multi-step redox pairs, through the Figure 5c Analysis of the cyclic voltammetry curves revealed that the electrode polarization between the two pairs of oxidation / reduction peaks in the Sn@3D-Zn / / PANI-V2O5 battery was lower than that in the Zn / / PANI-V2O5 battery. This phenomenon indicates that Sn@3D-Zn exhibits better reversibility. Simultaneously, the Sn@3D-Zn / / PANI-V2O5 battery demonstrates a higher current response, which is attributed to the larger reaction region and faster ion migration pathways provided by Sn@3D-Zn. Figure 5d Electrochemical impedance spectra of two batteries are shown. The Sn@3D-Zn / / PANI-V2O5 battery has a smaller radius, which means it has a smaller charge transfer internal resistance.

[0129] Figure 5e and Figure 5f , 5g The cycling performance of Sn@3D-Zn / / PANI-V2O5 and Zn / / PANI-V2O5 batteries, respectively, and their performance at 0.48 A g are demonstrated. -1The constant current charge-discharge curves at current densities from 10 to 300 volts are shown between 0.2 and 1.5 V. After 300 cycles, the Sn@3D-Zn / / PANI-V2O5 battery still provides 210 mAh g / L. -1 considerable capacity ( Figure 5f The average discharge coulombic efficiency is 99.2%, and the capacity retention is 60%, which is far higher than the 97.5 mAh g of ordinary Zn / / PANI-V2O5 batteries. -1 capacity ( Figure 5g With a capacity retention of 30.45%, the current density was increased to 0.96 A g. -1 The long-cycle performance of ordinary Zn / / PANI-V2O5 batteries and Sn@3D-Zn / / PANI-V2O5 batteries was further compared below, such as... Figure 5h As shown, the Sn@3D-Zn / / PANI-V2O5 battery provides 187.1 mAh g after 1000 cycles. -1 The reversible capacity is greater than that of ordinary Zn / / PANI-V2O5 batteries, which only retain 45.1mAh g. -1 Its meager capacity. Figure 5i and Figure 5j The changes in the galvanostatic charge-discharge curves of Sn@3D-Zn / / PANI-V2O5 batteries and ordinary Zn / / PANI-V2O5 batteries from 10th to 1000th cycles are shown respectively. Furthermore, as... Figure 5l As shown, the surface of a conventional zinc anode exhibits a significantly uneven and loose structure after cycling, but the Sn@3D-Zn anode still maintains a uniform and dense appearance after cycling. Figure 5k This indicates that Sn@3D-Zn can maintain a dendrite-free zinc deposition and stripping cycle during full-cell testing. These results demonstrate that, for both zinc-symmetric and zinc-ion batteries, the tin plating layer and the three-dimensional zinc substrate can indeed improve the cycle stability of the zinc anode.

[0130] Comparative Example 1:

[0131] The majority of the contents are the same as in Example 1, except that the Sn(OTf)2 solution is replaced with equimolar concentrations of tin chloride and stannous chloride solutions.

[0132] Figures 6a to 6d The SEM image and optical photograph of the zinc anode prepared in Comparative Example 1 are shown. Figure 6a As can be seen, the zinc sheet soaked in 0.03M SnCl4 showed no etched holes on its surface, and the amount of Sn crystals generated was also small. Figure 6bThis is an optical photograph of a Zn sheet after immersing it in 0.03M SnCl4 for 10 seconds. It is almost identical to a regular zinc sheet, showing no change from silver to gray. Figure 6c The image shows a SEM image of a Zn sheet after immersion in 0.03M SnCl2 for 10 seconds. It can be observed that there are no etched holes on the electrode surface, and the generated Sn crystals are not particularly uniform. Figure 6d The image shows an optical photograph of a Zn sheet after immersion in 0.03 MS nCl2 for 10 seconds. The gray color on the surface is not uniform.

[0133] In summary, this invention provides an economical, efficient, and industrially compatible method for converting ordinary commercial zinc foil into an aqueous zinc-ion battery anode suitable for long-term energy storage. A uniform metallic tin layer with a unique three-dimensional porous structure and zinc affinity is constructed on the zinc surface via simultaneous liquid-phase deposition to address the critical reaction interface problem in zinc anodes. Based on the analysis of the above experimental results, Sn@3D-Zn has the following advantages: 1. Enhanced ion transfer kinetics; 2. Reduced occurrence of electrochemical parasitic reactions and improved corrosion resistance of the zinc metal anode in weakly acidic aqueous electrolytes; 3. The three-dimensional zinc matrix results in a more uniform zinc ion concentration distribution, leading to a smoother zinc electrodeposition process. Benefiting from these characteristics, the strategy of rapidly modifying the zinc metal anode using Sn(OTf)2 has a positive impact on the performance testing of both symmetric and asymmetric batteries, exhibiting superior long-cycle stability, higher capacity retention, and a smoother deposition surface, providing a new design scheme for the fabrication of highly stable aqueous zinc-ion batteries.

[0134] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a tin-protected three-dimensional zinc metal anode with high cycle stability, characterized in that, Includes the following steps: (1) Weigh Sn(OTf)2 and dissolve it in deionized water to prepare Sn(OTf)2 solution; (2) Take the pretreated Zn sheet and immerse it in the Sn(OTf)2 solution in step (1). Then take it out, clean and dry it to obtain Sn@3D-Zn anode, which is the target product.

2. The method for preparing a tin-protected three-dimensional zinc metal anode with high cycle stability according to claim 1, characterized in that, In step (1), the concentration of Sn(OTf)2 solution is 0.01~0.05mol / L.

3. The method for preparing a tin-protected three-dimensional zinc metal anode with high cycle stability according to claim 1, characterized in that, In step (1), the concentration of Sn(OTf)2 solution is 0.03 mol / L.

4. The method for preparing a tin-protected three-dimensional zinc metal anode with high cycle stability according to claim 1, characterized in that, In step (2), the Zn wafer pretreatment process is as follows: first, use alcohol ultrasonic cleaning to remove any organic impurities that may exist on the surface, and then dry it in a vacuum drying oven at 60°C.

5. The method for preparing a tin-protected three-dimensional zinc metal anode with high cycle stability according to claim 1, characterized in that, In step (2), the soaking is carried out at room temperature.

6. The method for preparing a tin-protected three-dimensional zinc metal anode with high cycle stability according to claim 1, characterized in that, In step (2), the soaking time is 5-30 seconds.

7. The method for preparing a tin-protected three-dimensional zinc metal anode with high cycle stability according to claim 1, characterized in that, In step (2), the soaking time is 10 seconds.

8. A tin-protected three-dimensional zinc metal anode with high cycle stability, which is prepared by the preparation method according to any one of claims 1 to 7.

9. The application of the tin-protected three-dimensional zinc metal anode with high cycle stability as described in claim 8, characterized in that, This tin-protected three-dimensional zinc metal anode is used to prepare aqueous zinc-ion batteries, zinc-copper asymmetric batteries, or zinc-symmetric batteries.

10. The application of the tin-protected three-dimensional zinc metal anode with high cycle stability as described in claim 9, characterized in that, The specific preparation process of aqueous zinc-ion batteries is as follows: (A-1) Weigh V2O5 and dissolve it in deionized water at room temperature by stirring. Then add aniline and add hydrochloric acid to adjust the pH of the solution to 3 to obtain a mixed solution. (A-2) The mixed solution obtained in step (A-1) was transferred to a high-pressure hydrothermal reactor, heated to 120°C and reacted for 24 hours. Then it was cooled to room temperature and the reaction product was collected. After washing and drying, PANI-V2O5 was obtained. (A-3) Weigh the PANI-V2O5, acetylene black and polyvinylidene fluoride obtained in step (A-2), grind and mix them, then add N-methylpyrrolidone dropwise, and continue mixing and stirring to obtain a slurry; (A-4) The slurry obtained in step (A-3) is dropped onto carbon cloth and then dried to obtain the positive electrode of an aqueous zinc-ion battery for later use; (A-5) Cut the glass fiber diaphragm to the designed size and prepare a ZnSO4 aqueous solution as the electrolyte for later use; (A-6) The battery casing is of type CR2032. The casing is stacked in the following order: negative electrode shell → Sn@3D-Zn negative electrode → glass fiber separator → aqueous zinc-ion battery positive electrode → gasket → spring sheet → positive electrode shell. Then, the casing is sealed using a battery sealing machine to prepare an aqueous zinc-ion battery. When stacking the glass fiber separator, ZnSO4 aqueous solution is added as electrolyte. The specific preparation process of zinc symmetric solar cells is as follows: (B-1) Cut the glass fiber diaphragm to the designed size and prepare a ZnSO4 aqueous solution as the electrolyte for later use; (B-2) The battery casing is of type CR2032. It is stacked in the following order: negative electrode shell → Sn@3D-Zn → glass fiber separator → Sn@3D-Zn → gasket → spring sheet → positive electrode shell. Then, it is sealed using a battery sealing machine to prepare a zinc symmetric battery. When stacking the glass fiber separator, ZnSO4 aqueous solution is added as electrolyte. The specific preparation process of the zinc-copper asymmetric battery is as follows: (C-1) Cut glass fiber diaphragms and Cu foils to the designed dimensions and prepare ZnSO4 aqueous solution as electrolyte for later use; (C-2) Weigh out ZnSO4·7H2O, NaCl and H3BO3 and dissolve them in water to obtain a mixed solution; (C-3) A three-electrode system is prepared using Cu foil from step (C-1) as the working electrode, Pt sheet as the counter electrode, saturated calomel electrode as the reference electrode, and mixed solution from step (C-2) as the electrolyte. (C-4) using -3 mA cm -2 A constant current is applied to the Cu foil in the three-electrode system constructed in step (C-3) to deposit Zn, resulting in a Zn@Cu electrode sheet; (C-5) The Zn@Cu electrode sheet obtained in step (C-4) is immersed in Sn(OTf)2 aqueous solution, taken out, washed and dried to obtain Sn@Cu; (C-6) The battery casing is of type CR2032. It is stacked in the following order: negative electrode shell → Sn@3D-Zn → glass fiber separator → Sn@Cu → gasket → spring sheet → positive electrode shell. Then, it is sealed using a battery sealing machine to prepare a zinc-copper asymmetric battery. When stacking the glass fiber separator, ZnSO4 aqueous solution is added as electrolyte.

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