Zinc negative electrode of aqueous zinc ion battery as well as preparation method and application of zinc negative electrode

Abstract

The invention discloses a zinc negative electrode of a water-based zinc ion battery as well as a preparation method and application of the zinc negative electrode, and relates to the technical field of water-based zinc ion batteries. Aiming at dendritic crystal growth existing in a zinc negative electrode in an aqueous zinc ion battery, anions Cl <-> and SO4 < 2-> in a specific proportion are adopted, a solvation structure of Zn < 2 + > and electrode / electrolyte interface behaviors are regulated and controlled, electrochemical deposition kinetics of zinc is optimized, and finally a Zn < 2 + > migration path and a desolvation energy barrier are synergistically optimized. According to the zinc negative electrode provided by the invention, the uniformity and reversibility of zinc deposition are remarkably improved, an efficient and low-cost interface regulation and control strategy is provided for development of a high-performance water-based zinc ion battery, and the prepared water-based zinc ion battery has the advantages that the cycle life is excellent, coulombic efficiency attenuation is slowed down, the surface is free of dendritic crystals after circulation, and the service life is long. The method is suitable for the field of large-scale energy storage and flexible electronic equipment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aqueous zinc-ion batteries, in particular to a zinc anode of an aqueous zinc-ion battery and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of economy and technology, the problem of gradual depletion of fossil energy is increasingly prominent, so it is urgent to research, develop and utilize efficient and clean renewable energy. Among many renewable energies, the development of lithium-ion battery technology is limited by potential safety hazards and the reduction of lithium resources. Zinc-ion batteries exhibit excellent safety performance, which is one of the effective ways to solve energy crisis and environmental problems. Among other alkali metals, metal zinc (Zn) stands out due to its high theoretical capacity (820 mAh / g), low plating / delamination potential (-0.76 V vs. standard hydrogen electrode), and easy processing. However, due to the safety problems such as flammability, corrosion and poor thermal stability of the organic plating solution, the development of traditional zinc-ion batteries is limited. In comparison, aqueous zinc-ion batteries (AZIB) are considered as the preferred direction of the next generation of new energy storage batteries due to their high safety and high energy density, laying the foundation for zinc-ion batteries as a future research direction.

[0003] During the electrochemical reaction process of the aqueous zinc-ion battery, serious dendrite growth problem is prone to occur on the zinc anode. Dendrite growth refers to the tip effect that occurs during zinc nucleation, causing zinc to accumulate at the protrusions and form dendrites. The continuous growth of zinc dendrites not only pierces the separator, but also causes short circuit of the battery, ultimately leading to reduced cycle life and reduced coulombic efficiency of the aqueous zinc-ion battery.

[0004] In order to inhibit zinc dendrites, the existing technology mainly includes surface coating modification, plating solution additive optimization, etc. For example, CN118136977B discloses a polyurethane modified separator, but its dendrite inhibition effect is limited. In addition, although the conventional plating solution (such as ZnSO4+Na2SO4) can partially stabilize the interface, it cannot completely solve the dendrite problem, and high concentration plating solution (the concentration generally reaches 2 M) is prone to cause side reactions.

[0005] Therefore, it is urgent to develop a low-cost, efficient and easy-to-industrialize zinc anode interface optimization method. SUMMARY

[0006] In order to solve the uncontrollable growth of zinc dendrites in the existing aqueous zinc-ion battery, the present application provides a zinc anode of an aqueous zinc-ion battery and a preparation method and application thereof, aiming to provide a new zinc anode preparation method to precisely control the anions Cl - and SO4 2- in the plating solution; optimize the Zn2+ The solvation structure and electrode / electrolyte interface behavior of the application effectively inhibit zinc dendrite formation, improve the cycle stability and service life of the battery. The technical solution of the application is realized by the following technologies.

[0007] A preparation method of a zinc negative electrode of an aqueous zinc ion battery, characterized in that a zinc sheet or zinc foil and a metal substrate are inserted into an electroplating solution, and electricity is passed to electroplating deposit metal zinc on the surface of the metal substrate to obtain the zinc negative electrode; the concentration of Cl - in the electroplating solution is 0.05-0.5 M, and the concentration of SO4 2- is 0.1-1 M.

[0008] Further, in the electroplating solution, the molar ratio of Cl - to SO4 2- is (0.05-5):1.

[0009] Further, the concentration of Cl - in the electroplating solution is 0.5 M, and the concentration of SO4 2- is 0.25 M.

[0010] Further, in the electroplating solution, Cl - is provided by ZnCl2, and SO4 2- is provided by NaSO4.

[0011] Further, in the electroplating solution, the concentration of ZnCl2 is 0.025-0.25 M, and the concentration of NaSO4 is 0.1-1 M.

[0012] Further, the pH value of the electroplating solution is 3.0-6.0.

[0013] Further, the electroplating time is not less than 30 min.

[0014] Further, the current density of the electroplating is 5-20 mA / cm 2 .

[0015] The application provides a zinc negative electrode of an aqueous zinc ion battery, which is prepared by any one of the preparation methods.

[0016] The application also provides the application of the zinc negative electrode prepared by any one of the preparation methods in preparing an aqueous zinc ion battery.

[0017] The application also provides an aqueous zinc ion battery, which comprises a zinc negative electrode, and the zinc negative electrode is prepared by any one of the preparation methods.

[0018] The zinc negative electrode can be applied to different types of aqueous zinc ion batteries, such as Zn / / Zn symmetric batteries, half batteries or full batteries.

[0019] The structure of the Zn / / Zn symmetric battery comprises a zinc negative electrode, a separator and a zinc positive electrode, and the zinc negative electrode and the zinc positive electrode are filled with an electrolyte.

[0020] Specifically, one of the assembly methods of the Zn / / Zn symmetric battery is as follows: a zinc negative electrode sheet (with the light surface facing up) is sequentially placed in a negative electrode shell, a separator (for example, a glass fiber separator) is added and electrolyte is added dropwise, a zinc positive electrode sheet (with the light surface facing down) is placed, a 304 stainless steel gasket and a spring are placed, and finally, the battery is packaged.

[0021] The structure of the half battery claimed in the application is similar to that of the Zn / / Zn symmetric battery, and the difference is that the negative electrode is replaced with a Cu@Cl-Zn negative electrode material, and the positive electrode is a common copper foil (Cu). The Cu@Cl-Zn refers to a copper foil or copper sheet on which zinc is electroplated using zinc chloride as an electroplating solution.

[0022] Alternatively, the structure of the half battery is basically the same as that of the Zn / / Zn symmetric battery, and the difference is that the zinc positive electrode is replaced with another metal electrode.

[0023] Specifically, the positive electrode material of the Zn / / Zn symmetric battery is the same as the negative electrode material, and the positive electrode material in the half battery can be selected from other metal materials.

[0024] Specifically, taking the Zn / / Cu half battery as an example, the preparation method thereof is basically the same as that of the Zn / / Zn symmetric battery, and the difference is that the zinc positive electrode sheet is replaced with a copper sheet with a diameter of 12 mm after cleaning.

[0025] The structure of the full battery claimed in the application is similar to that of the Zn / / Zn symmetric battery and the half battery, and the difference is that the negative electrode is replaced with a Cu@Cl-Zn negative electrode material. The Cu@Cl-Zn refers to a copper foil or copper sheet on which zinc is electroplated using zinc chloride as an electroplating solution.

[0026] Alternatively, the structure of the full battery is basically the same as that of the Zn / / Zn symmetric battery, and the difference is that the zinc positive electrode is replaced with another electrode material.

[0027] Specifically, the positive electrode material in the full battery can be selected from vanadium-based oxides, manganese-based oxides, (NH4) x VO3, Prussian blue analogues and other metal materials.

[0028] Specifically, taking the Cu@Cl-Zn / / (NH4) x VO3 full battery as an example, the Cu@Cl-Zn / / (NH4) xOne of the preparation methods of the VO3 full battery is: sequentially installing a Cu@Cl-Zn zinc negative electrode sheet in a negative electrode shell, adding a separator (for example, a glass fiber material separator), and dropping an electrolyte, and then putting (NH4) x VO3 positive electrode sheet (active material facing down, loading amount calculated according to the formula), and then putting in a gasket and a spring, and finally packaging.

[0029] Optionally, the positive electrode of the aqueous zinc ion battery can be selected from at least one of vanadium-based oxides, manganese-based oxides or prussian blue analogues.

[0030] The present application focuses on the regulation mechanism of anions in the electroplating preparation of a zinc negative electrode; the solvation structure of different anions (such as SO4 2- , Cl - , etc.) in the electroplating solution and the interaction thereof with Zn 2+ are mainly explored, the influence of the same on the zinc deposition morphology, interface stability and electrode electrochemical performance is revealed, and the dynamic regulation process of the anion to the Zn / electroplating solution interface is studied by XRD (X-ray diffraction) and SEM (scanning electron microscope).

[0031] On this basis, the present application provides a preparation method of a zinc negative electrode of an aqueous zinc ion battery, and finally uses the zinc negative electrode to assemble an aqueous zinc ion battery or a zinc-air battery with long cycle stability, low attenuation efficiency of coulomb efficiency, no dendrite on the surface after charge-discharge cycle and good structural stability.

[0032] Compared with the prior art, the present application has the following advantages:

[0033] 1. The present application provides a preparation method of a zinc negative electrode of an aqueous zinc ion battery, which precisely regulates the anions Cl - and SO4 2- in the electroplating solution, effectively suppresses the self-discharge of the battery, suppresses the formation of zinc dendrites, reduces the nucleation overpotential, reduces the corrosion current, improves the corrosion potential, and improves the cycle stability and service life of the battery.

[0034] 2. A large number of experiments show that, by combining XRD and SEM, it is confirmed that the anions Cl - and SO4 2- suppress the growth of dendrites by regulating the diffusion path and interface adsorption behavior of Zn 2+ . Specifically, Cl - induces zinc to grow along the (002) crystal plane, forms a dense deposition layer, and significantly suppresses the formation of dendrites; SO4 2- reconstructs the electric double layer structure of the electrode / electroplating solution interface, and improves the uniformity of zinc deposition. In summary, Cl⁻ and SO4 2-By promoting anode dissolution, optimizing current distribution, refining grain, and inhibiting impurity co-deposition, the plating layer quality is improved.

[0035] 3. The zinc negative electrode prepared by the preparation method of the application is used to prepare a water-based zinc ion battery, so that the Cu@Cl-Zn symmetrical battery has a long cycle stability of more than 600 hours at a high current density of 5 mA / cm 2 , the cycle life is improved from 80 h of pure zinc to 600 h, the polarization voltage is reduced, and the low polarization voltage is less than 71 mV at a high current density of 5 mA / cm 2 ; the interface impedance is optimized. The prepared half battery (Cu@Cl-Zn / / Cu) has a slow attenuation of coulombic efficiency at a high current density of 5 mA / cm 2 , and no dendrite is formed on the surface after cycling. In the full battery test (taking Cu@Cl-Zn / / (NH4) x VO3 as an example), the initial capacity of the battery is 300 mAh / g due to the low specific capacity of the positive electrode material ((NH4) x VO3), although the capacity decreases slightly subsequently, but it shows potential for practical application.

[0036] 4. The water-based zinc ion battery prepared by the application is compatible with the lead-acid battery production line, is suitable for 48V communication base stations, and is widely used in technical fields such as low-altitude economy and robots; the zinc iodine battery, zinc sulfur battery, zinc bromine flow battery and other zinc metal-based batteries using zinc as the negative electrode can also be prepared. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a copper foil zinc plating process flow chart of the Cu@Cl-Zn zinc negative electrode material (zinc negative electrode sheet).

[0038] Figure 2 is a real object diagram of pure copper foil (Cu), Cu@S-Zn and Cu@Cl-Zn.

[0039] Figure 3 is a battery assembly schematic diagram.

[0040] Figure 4 In the figure, a is the detection diagram of the X-ray diffractometer of the ordinary pure copper foil and the ordinary pure zinc foil; b is the detection diagram of the X-ray diffractometer of the Cu@Cl-Zn negative electrode material and the Cu@S-Zn negative electrode material.

[0041] Figure 5 In the figure, a and b are SEM characterization diagrams of the pure copper foil at different magnifications; c is the SEM characterization diagram of the Cu@S-Zn negative electrode material, and d is the SEM characterization diagram of the Cu@Cl-Zn negative electrode material.

[0042] Figure 6 and Figure 7are analysis diagrams of galvanostatic charge-discharge test results of BZn symmetric battery, Cu@Cl-Zn symmetric battery and Cu@S-Zn symmetric battery.

[0043] Figure 8 and Figure 9 are analysis diagrams of galvanostatic charge-discharge test results of BZn / / Cu half battery, Cu@Cl-Zn / / Cu half battery and Cu@S-Zn / / Cu half battery.

[0044] Figure 10 is an analysis diagram of CV test results of Cu@Cl-Zn full battery.

[0045] Figure 11 is a specific capacity diagram of BZn full battery, Cu@Cl-Zn full battery and Cu@S-Zn full battery.

[0046] Figure 12 is a single cycle diagram of BZn full battery, Cu@Cl-Zn full battery and Cu@S-Zn full battery in the same charge-discharge interval.

[0047] Figure 13 In the figures, a is a diagram of three Cu@S-Zn full batteries lighting LED lamps in series; and b is a diagram of measuring voltage of three Cu@Cl-Zn full batteries in series by using a multimeter. DETAILED DESCRIPTION

[0048] The technical solutions of the present application will be described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0049] In some embodiments of the present application, the preparation method of the zinc negative electrode of the aqueous zinc ion battery is as follows: inserting a zinc sheet or a zinc foil and a metal substrate into an electroplating solution, and passing electricity to electroplate and deposit metal zinc on the surface of the metal substrate to obtain the zinc negative electrode. - The concentration of Cl 2- in the electroplating solution is 0.05-0.5 M, and the concentration of SO4 2- in the electroplating solution is 0.1-1 M.

[0050] Optionally, the molar ratio of Cl - to SO4 2- in the electroplating solution is (0.05-5):1.

[0051] Specifically, the concentration of Cl - in the electroplating solution is 0.5 M, and the concentration of SO4 2- in the electroplating solution is 0.25 M.

[0052] Optionally, in the electroplating solution, the concentration of ZnCl2 is 0.025-0.25 M, and the concentration of Na2SO4 is 0.1-1 M. - provided by ZnCl2, SO4 2- provided by NaSO4.

[0053] Specifically, in the electroplating solution, the concentration of ZnCl2 is 0.025-0.25 M, and the concentration of Na2SO4 is 0.1-1 M.

[0054] Optionally, the pH value of the electroplating solution is 3.0-6.0.

[0055] Specifically, the pH value of the electroplating solution is 3.0, 4.0, 5.0, or 6.0.

[0056] Optionally, the electroplating time is not less than 30 min. Specifically, the electroplating time is 40 min, 50 min, 60 min, 80 min, or 90 min.

[0057] Optionally, the electroplating current density is 5-20 mA / cm 2 . Specifically, the electroplating current density is 5 mA / cm 2 , 10 mA / cm 2 , 15 mA / cm 2 , or 20 mA / cm 2 .

[0058] Optionally, in some embodiments of the present application, the preparation method of the provided electroplating solution is as follows:

[0059] (1) Zinc chloride and sodium sulfate solids are mixed according to a predetermined molar concentration, and then stirred with deionized water by magnetic stirring until completely dissolved.

[0060] (2) The solution state of the electroplating solution is observed. During the magnetic stirring process, the system gradually becomes a white turbid liquid. After stopping stirring and standing for 30-60 min, the supernatant is taken as the electroplating solution for preparing the zinc negative electrode of the aqueous zinc ion battery.

[0061] In other embodiments of the present application, the zinc negative electrode prepared by the above preparation method is used to assemble an aqueous zinc ion battery.

[0062] The zinc negative electrode provided by the present application can be applied to different types of aqueous zinc ion batteries, such as Zn / / Zn symmetric batteries, half-batteries, or full-batteries.

[0063] The structure of the Zn / / Zn symmetric battery includes a zinc negative electrode, a separator, and a zinc positive electrode, and the zinc negative electrode and the zinc positive electrode are filled with an electrolyte.

[0064] Specifically, one of the assembly methods of the Zn / / Zn symmetric battery is as follows: sequentially place a zinc negative electrode sheet (the light surface faces upward) in the negative electrode shell, add a glass fiber diaphragm and drop the electrolyte, place a zinc positive electrode sheet (the light surface faces downward), then place a 304 stainless steel gasket and a 304 stainless steel spring, and finally seal.

[0065] Specifically, the positive electrode material in the full battery can be selected from at least one of vanadium-based oxides, manganese-based oxides, (NH4) x VO3, Prussian blue analogues and other metal materials.

[0066] Specifically, the Cu@Cl-Zn / / (NH4) x VO3 full battery is taken as an example, the Cu@Cl-Zn / / (NH4) x VO3 full battery is taken as an example, the Cu@Cl-Zn / / (NH4) x VO3 full battery is taken as an example, the Cu@Cl-Zn / / (NH4)

[0067] Optionally, the positive electrode of the aqueous zinc ion battery can be selected from at least one of vanadium-based oxides, manganese-based oxides or Prussian blue analogues

[0068] at least one of the above.

[0069] Embodiment 1

[0070] The preparation method of the zinc negative electrode of the aqueous zinc ion battery provided in the embodiment is as follows:

[0071] 1. Preparation of S-Cl and S-S electroplating solutions

[0072] (1) Add 2.72 g of zinc chloride (0.02 mol) and 2.84 g of sodium sulfate (0.02 mol) to 80 mL of deionized water, and stir with a magnetic stirrer until completely dissolved. At this time, the solution system gradually becomes a white turbid liquid.

[0073] That is, the concentration of NaSO4 is 0.25 M, and the concentration of ZnCl2 is 0.25 M.

[0074] (2) After stopping the magnetic stirring, stand for 30 min, and after the solution is layered, take the supernatant as the electroplating solution for preparing the metal zinc negative electrode of the aqueous zinc ion battery, and mark it as S-Cl electroplating solution.

[0075] Similarly, by using a method similar to the above, replace ZnCl2 with ZnSO4 of the same concentration, that is, use ZnSO4 and Na2SO4 to prepare the electroplating solution, and mark it as S-S electroplating solution.

[0076] 2. Preparation of zinc negative electrode sheet

[0077] (1) Cu@Cl-Zn negative electrode sheet and preparation of Cu@Cl-Zn negative electrode sheet

[0078] ① Firstly, take a 0.1 mm thick copper foil, wipe the surface with anhydrous ethanol to remove oxides, and dry; then use a 12 mm punching machine to punch into a circular electrode sheet.

[0079] Prepare a piece of rectangular zinc foil with a size similar to the above copper foil. Clean the surface of the copper foil and zinc negative electrode with deionized water and dry.

[0080] ② Pour the prepared S-Cl electroplating solution into a 100 mL beaker, and fix the zinc foil and copper foil in parallel on the clamping device of the three-electrode system, ensuring that the electrode spacing (25 mm) is consistent. Connect the electrochemical workstation, set the constant current mode, control the current density to be 5 mA / cm 2 , and the electroplating time is 90 min, to complete the uniform deposition of zinc, and obtain Cu@Cl-Zn negative electrode material.

[0081] Similarly, replace the S-Cl electroplating solution with S-S electroplating solution to prepare Cu@S-Zn negative electrode material.

[0082] ③ After electroplating, the Cu@Cl-Zn negative electrode material or Cu@S-Zn negative electrode material is immersed in deionized water for ultrasonic cleaning for 5 min to remove the surface residual electroplating solution. After drying, the corresponding Cu@Cl-Zn negative electrode sheet or Cu@S-Zn negative electrode sheet with a diameter of 12 mm is obtained.

[0083] (2) Cut the pure Zn negative electrode sheet into a 0.2 mm thick square zinc foil, and use a 12 mm punching machine to punch the zinc negative electrode material, which is recorded as BZn negative electrode sheet.

[0084] 3. Preparation of positive electrode sheet

[0085] (1) The Zn / / Zn symmetric battery of this embodiment has the same positive electrode material and negative electrode material.

[0086] (2) The Zn / / Cu half-cell of this embodiment uses a 12 mm diameter copper foil cleaned with deionized water and dried as the positive electrode.

[0087] (3) The positive electrode material and positive electrode sheet preparation method of the Cu@Cl-Zn / / (NH4) x VO3 full cell is as follows.

[0088] ① Weigh 1.0 g NH4VO3 and dissolve it in 250 mL of deionized water. Stir in a 75°C water bath until completely dissolved. Add 10 mmol thiourea and slowly add dilute sulfuric acid to adjust the pH to below 2.0. Heat to 90°C and stir for 2.5 h, then cool to room temperature.

[0089] ②The reaction solution obtained in step ① was washed five times alternately with deionized water and ethanol. It was then vacuum dried at 60℃ for 12 hours to obtain the precursor powder.

[0090] ③ Mix the precursor powder, acetylene black (conductive agent), and polyvinylidene fluoride (PVDF, binder) in a mass ratio of 7:2:1, grind for 10 min, add 4 mL of 1-methyl-2-pyrrolidone (NMP) and stir for 40 min to form a slurry.

[0091] ④ Coat the slurry obtained in step ③ onto carbon paper and dry it under vacuum at 80°C for 6 hours to obtain (NH4) with a thickness of 100 μm. x VO3 cathode material.

[0092] ⑤ (NH4) x VO3 cathode material is stamped into circular electrode sheets with a diameter of 12 mm to obtain (NH4). x For the VO3 positive electrode, calculate the loading. Active material mass = (mass after coating – average mass of blank carbon paper) × 0.7.

[0093] 4. Assemble the battery

[0094] Battery assembly diagram as shown Figure 3 As shown. The positive electrode shell is at the bottom, conducting positive current and providing protection. A spring contact on top assists in conduction and buffering. A gasket is used for insulation. The positive electrode plate participates in the reduction reaction, storing and releasing energy. A glass fiber diaphragm allows zinc ions to pass through, preventing short circuits. The negative electrode plate participates in the oxidation reaction. The topmost negative electrode shell conducts negative current, protecting the internal components.

[0095] (1) Zn / / Zn symmetrical battery: Place a zinc negative electrode sheet (smooth side up) in the negative electrode shell, add a separator (glass fiber separator) and drop ZnSO4 electrolyte, then place a zinc positive electrode sheet (smooth side down), cover with a spring and a gasket and then seal.

[0096] In this embodiment, the Zn / / Zn symmetric cell uses a pure Zn negative electrode sheet, a Cu@Cl-Zn negative electrode sheet, or a Cu@S-Zn negative electrode sheet as the negative electrode, and uses the same material as the negative electrode as the positive electrode.

[0097] The Zn / / Zn symmetric cells obtained by the final assembly are denoted as BZn symmetric cells, Cu@Cl-Zn symmetric cells, and Cu@S-Zn symmetric cells, respectively.

[0098] (2) Zn / / Cu half-battery: The steps are basically the same as those of Zn / / Zn, and pure Zn negative plate, Cu@Cl-Zn negative plate or Cu@S-Zn negative plate are used as the negative electrode. The difference is that the zinc positive plate is replaced by a pre-cleaned 12 mm copper foil.

[0099] The finally assembled Zn / / Cu half-batteries are respectively denoted as BZn / / Cu half-battery, Cu@Cl-Zn / / Cu half-battery and Cu@S-Zn / / Cu half-battery.

[0100] (3) Zn / / (NH4) x VO3 full battery: The zinc negative plate, the separator and the electrolyte are sequentially put into the negative electrode shell, and then (NH4) x VO3 positive plate (the loading amount is calculated according to the formula, 2.18 mg) is put into 304 stainless steel gasket and spring, and finally packaged. In this embodiment, the Zn / / (NH4) x VO3 full battery is assembled with pure Zn negative plate, Cu@Cl-Zn negative plate or Cu@S-Zn negative plate as the negative electrode.

[0101] The finally assembled Zn / / (NH4) x VO3 full batteries are respectively denoted as BZn full battery, Cu@Cl-Zn full battery and Cu@S-Zn full battery. The obtained Cu@Cl-Zn full battery can light up a string of LED lamps by taking three in series, as shown in Figure 13 .

[0102] Figure 1 is the copper foil zinc plating process flow chart of the Cu@Cl-Zn zinc negative material (zinc negative plate) of this embodiment. The copper foil is plated according to the operation in the figure, and the Cu@Cl-Zn material can be prepared. Figure 2 is the actual picture of pure copper foil (Cu), Cu@S-Zn negative material and Cu@Cl-Zn negative material. As can be seen from the figure, the copper foil plated by S-Cl plating solution is uniformly deposited, and the plating layer is relatively thick, and the plating surface is smooth and smooth. The Cu@S-Zn negative plate is deposited unevenly, and the plating layer is thin, and even some places are not plated.

[0103] Figure 4 is the XRD test diagram of the zinc negative electrode prepared in this embodiment. Figure 4 The XRD diffraction peaks of ordinary pure copper foil, ordinary pure zinc foil, Cu@S-Zn negative material and Cu@Cl-Zn negative material are compared. It can be seen that the ordinary zinc foil shows the typical peak of hexagonal close-packed (HCP) structure (such as (100) crystal face); the proportion of (002) crystal face in the XRD result of Cu@S-Zn negative material is high, which indicates that the horizontal orientation proportion of (002) crystal face is higher; the (002) crystal face of Cu@Cl-Zn negative material (Cl -The proportion of the (101) crystal plane level orientation of the copper foil is increased, which proves that the Cl - induced preferred orientation growth.

[0104] Figure 5 are SEM test images of pure copper foil and different zinc negative materials. Among them, Figure 5 a and 5b are SEM images of pure copper foil at different magnifications; Figure 5 c is an SEM image of Cu@S-Zn zinc negative material, and it can be seen that the surface of Cu@S-Zn zinc negative is flaky and easy to form dendrites. Figure 5 d is an SEM image of Cu@Cl-Zn zinc negative material, and the zinc deposition morphology after S-Cl electroplating solution regulation is dense and uniform, with few dendrite morphology, verifying the effectiveness of the anion regulation strategy.

[0105] For the symmetric battery, first charge at a current of 5 mA / cm 2 for 12 min, then stand for 30 s, then discharge at a current of 5 mA / cm 2 for 12 min, and then stand for 30 s; repeat the cycle of charging and discharging in this way. Figure 6 and Figure 7 are the constant current charge-discharge test results of the BZn symmetric battery, Cu@Cl-Zn symmetric battery and Cu@S-Zn symmetric battery prepared in this embodiment. From the Figure 6 Zn / / Zn symmetric battery constant current charge-discharge test results, it can be seen that the Cu@Cl-Zn symmetric battery realizes stable cycle for more than 600 hours, showing stable long cycle performance, while the life of the Cu@S-Zn symmetric battery and the BZn symmetric battery are both less than 80 hours. From Figure 7 it can be seen that the Cu@Cl-Zn symmetric battery cycles for 1000 times, and the polarization voltage is only 71 mV; while the Cu@S-Zn symmetric battery only cycles for 58 hours, and a short circuit occurs, and the polarization voltage reaches 148 mV; and the polarization voltage of the BZn symmetric battery is 134 mV. This shows that the Cu@Cl-Zn symmetric battery can promote the uniform deposition of Zn 2+ and inhibit the growth of zinc dendrites, so that the cycle stability is obviously improved.

[0106] For the half battery, first stand for 30 s, then discharge at a current of 5 mA / cm 2 for 12 min, then stand for 30 s, then charge at a current of 5 mA / cm 2 for 12 min; repeat the cycle of charging and discharging in this way. Figure 8 and Figure 9 are the constant current charge-discharge test results of the BZn / / Cu half battery, Cu@Cl-Zn / / Cu half battery and Cu@S-Zn / / Cu half battery prepared in this embodiment. From theFigure 8 It can be seen that the BZn / / Cu half-cell and the Cu@S-Zn / / Cu half-cell subsequently appeared short circuit, and the coulombic efficiency decreased sharply; while the Cu@Cl-Zn / / Cu half-cell used S-Cl plating solution, the decrease of the coulombic efficiency was smaller in multiple cycles, and it could be maintained at a high level for a long time, which showed good cycle stability. Compared with the Cu@S-Zn / / Cu half-cell, the Cu@Cl-Zn / / Cu half-cell using S-Cl plating solution had fewer dendrites on the electrode surface after cycling, which further verified its performance advantage. It can be seen from Figure 9 that the voltage of the Cu@Cl-Zn / / Cu system changed more smoothly, the polarization voltage was 61 mV, and the stability of the charging and discharging process was good.

[0107] Place the connected battery in a constant temperature environment to avoid temperature fluctuations affecting the results. Start the electrochemical workstation and run the CV test program. The instrument will automatically scan according to the set voltage range and rate: start from the initial voltage, scan to the high voltage (oxidation direction) at the set rate, record the current change with voltage, until the upper limit voltage; after reaching the upper limit, scan in the opposite direction to the lower limit voltage (reduction direction), complete one cycle; repeat the scan to the set number of cycles to generate a CV curve. Figure 10 is the CV test result analysis diagram of the Cu@Cl-Zn full cell. It can be seen from Figure 10 that the oxidation peak potential is about 1.26 V, which corresponds to the oxidation process of VO3 x- ; the reduction peak potential is about 0.722 V, which corresponds to the reduction process of VO3 x- . The measured result peak shape is symmetrical and sharp, indicating that the electrode has good reversibility.

[0108] Figure 11 is the discharge specific capacity diagram of the BZn full cell, the Cu@Cl-Zn full cell and the Cu@S-Zn full cell made in Example 1. It can be seen from Figure 11 that the capacity of the Cu@Cl-Zn full cell is higher than the initial capacity of the BZn full cell and the Cu@S-Zn full cell, and the coulombic efficiency stability is also higher than the BZn / / (NH4) x VO3 full cell and the Cu@S-Zn / / (NH4) x VO3 full cell.

[0109] The test method is similar to that of the half-cell, except that the current size of the full cell is determined according to the mass of the active material (5 A / g). Assuming that the mass of the active material is 2 mg, first stand for 30 s, then constant current charging to 1.8 V at a current of 10 mA / cm 2 , stand for 30 s again, and then charge at a current of 10 mA / cm 2constant current discharge to 0.4 V under the current; repeat the cycle in this way. Figure 12 are the single cycle diagrams of BZn full cell, Cu@Cl-Zn full cell and Cu@S-Zn full cell in the same charge-discharge interval. From Figure 12 It can be seen that after 700 cycles, the capacity of Cu@Cl-Zn full cell is still higher than that of BZn / / (NH4) x VO3 full cell and Cu@S-Zn / / (NH4) x VO3 full cell. As can be seen from the curves in the figure, the capacity of Cu@Cl-Zn / / (NH4) x VO3 full cell is also lower than that of BZn / / (NH4) x VO3 full cell and Cu@S-Zn / / (NH4) x VO3 full cell.

[0110] Figure 13 In this embodiment, a is a diagram of three Cu@Cl-Zn full cells lighting LED lamp in series; b is a diagram of three Cu@Cl-Zn full cells in series using a multimeter to measure voltage. It can be seen that three Cu@Cl-Zn full cells can easily light a string of LED lamp, and the voltage of three Cu@Cl-Zn full cells in series is 4.886 V.

[0111] Example 2

[0112] The preparation method of the zinc negative electrode of the aqueous zinc ion battery provided in this embodiment is basically the same as that in Example 1, and the difference lies in that:

[0113] (1) When preparing the electroplating solution, stop magnetic stirring and stand for 40 min.

[0114] (2) When preparing the Zn-Cu composite electrode, set the constant current mode, control the current density to be 8 mA / cm 2 , and the electroplating time is 60 min.

[0115] Example 3

[0116] The preparation method of the zinc negative electrode of the aqueous zinc ion battery provided in this embodiment is basically the same as that in Example 1, and the difference lies in that:

[0117] (1) When preparing the electroplating solution, stop magnetic stirring and stand for 50 min.

[0118] (2) When preparing the Zn-Cu composite electrode, set the constant current mode, control the current density to be 10 mA / cm 2 , and the electroplating time is 45 min.

[0119] The above detailed description describes the implementation of the present application, but the present application is not limited to the specific details in the above implementation. Within the scope of the claims and technical concepts of the present application, various simple modifications and changes can be made to the technical solutions of the present application, and these simple modifications all belong to the protection scope of the present application.

Claims

1. A method for preparing a zinc anode of an aqueous zinc-ion battery, characterized in that, The zinc sheet or zinc foil and the metal substrate are inserted into an electroplating solution, and electricity is passed to electroplating deposit zinc on the surface of the metal substrate to obtain the zinc negative electrode; the concentration of Cl in the electroplating solution is 0.05-0.5 M, and the concentration of SO4 is 0.1-1 M. - 2- ​​ 2. The method of producing a zinc anode for aqueous zinc-ion batteries according to claim 1, characterized in that, The molar ratio of Cl - and SO4 2- in the plating solution is (0.05-5):

1.

3. The method of producing a zinc anode for aqueous zinc-ion batteries according to claim 2, characterized in that, Cl in the electroplating solution - The concentration is 0.5 M, SO4 2- The concentration was 0.25 M.

4. The method of producing a zinc anode for aqueous zinc-ion batteries according to claim 1, characterized by, Cl - provided by ZnCl2, SO4 2- provided by NaSO4; Further, the concentration of ZnCl2 is 0.025-0.25 M, and the concentration of NaSO4 is 0.1-1 M.

5. The method of producing a zinc anode for aqueous zinc-ion batteries according to claim 1, characterized in that, The pH value of the electroplating solution is 3.0-6.

0.

6. The method of producing a zinc anode for aqueous zinc-ion batteries according to claim 1, wherein The electroplating time is not less than 30 min.

7. The method of producing a zinc anode for aqueous zinc-ion batteries according to claim 1, characterized in that, The current density of the electroplating is 5-20 mA / cm 2 .

8. A zinc anode for aqueous zinc-ion batteries, characterized in that, Prepared by the preparation method of any one of claims 1-7.

9. Application of the zinc negative electrode prepared by the preparation method of any one of claims 1-7 or the zinc negative electrode of claim 8 in preparation of an aqueous zinc ion battery.

10. An aqueous zinc-ion battery, characterized in that, The structure comprises a zinc negative electrode prepared by the preparation method of any one of claims 1-7 or the zinc negative electrode of claim 8.

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