Method for stabilizing zinc negative electrode through Mn3V19 self-assembled film

Abstract

The invention provides a method for protecting a metal zinc negative electrode of a zinc ion battery through a self-assembled film. The preparation method comprises the following steps: dissolving [H6Mn3V19O46 (H2O)]. 30H2O (Mn3V19 for short) with different masses in an N, N-dimethylformamide organic solvent with the same volume, and soaking a zinc sheet in the mixed solution to form the Mn3V19 self-assembled film. The newly developed Mn3V19 self-assembly interface film is compact and uniform, can avoid direct contact between an electrolyte and the surface of the zinc foil, can provide rich zinc nucleation sites, and promotes uniform deposition of Zn < 2 + >, thereby inhibiting growth of zinc dendrites and generation of various side reactions. Electrochemical data shows that the service life of the zinc symmetric battery attached with the self-assembly interfacial film exceeds 500 hours under the conditions of 5mAcm <-2 > and 2mAh <-2 >, and a very high galvanization / stripping process is shown. The method disclosed by the invention is simple in process and environment-friendly, reaction conditions are easy to control, the performance of the water-based zinc ion battery can be effectively improved, and the method has great significance on actual application.

Description

Technical Field

[0001] The present invention belongs to the field of aqueous zinc-ion batteries, and more specifically, relates to a method for stabilizing zinc anodes through Mn 3 V 19 self-assembled films and a zinc-ion battery constructed based on this solution.

[0002] Research Background

[0003] The rapid development of electric vehicles, portable electronic products, and grid-scale energy storage has led to an increasing demand for high-efficiency energy storage devices with low cost, long lifespan, and high energy density. Lithium-ion batteries (LIBs) have become the most widely used energy storage devices due to their reversible cycling and high energy density characteristics. However, they have drawbacks such as high cost, limited lithium resources, and toxic electrolytes, which are not conducive to the development of large-scale energy storage devices. In recent years, rechargeable aqueous batteries have received extensive attention due to their high specific capacitance, low cost, excellent safety, and eco-friendliness. Among various aqueous batteries, zinc-ion batteries (ZIBs) are considered one of the most promising candidate batteries due to their high theoretical capacity (820 mAh g -1 ), low redox potential (-0.76 vs. standard hydrogen electrode), and high overpotential for hydrogen evolution in zinc negative electrode electrolytes.

[0004] Although several different types of aqueous zinc-ion batteries have made great progress in the past few decades, they also face some problems that are difficult to overcome. On the one hand, dendrites formed during cycling result in a low Coulombic efficiency (CE). At the same time, the generated dendrites can pierce the separator, leading to battery short-circuit failure. In addition, the dendrites have low adhesion to the metal matrix and are easily detached from the negative electrode to form "dead zinc", reducing the capacity of the negative electrode. On the other hand, the hydrogen evolution reaction on the zinc metal surface consumes water in the electrolyte, corrodes the surface of the metal negative electrode, and the generated gas can also cause battery inflation and electrolyte leakage. Therefore, finding a method to protect the zinc electrode and inhibit the growth of zinc dendrites is extremely urgent. Summary of the Invention

[0005] To address the above problems, the present invention provides a method for protecting zinc anodes with simple process, low cost, and easy to achieve large-scale production. By self-assembling an Mn 3 V 19 interface film on the zinc anode, it solves the problems of dendrite growth, hydrogen evolution, corrosion passivation, etc. existing in the zinc anodes of existing aqueous zinc-ion batteries, and exhibits good cycle stability and rate performance.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] Mn 3 V 19Method for stabilizing zinc anode with self-assembled film, successively cleaning zinc sheet with ultrapure water containing 0.1-1 mol L -1 HCl, ultrapure water, and absolute ethanol, and immersing the zinc sheet in a mixed solution of Mn 3 V 19 -N,N-dimethylformamide. The immersion time of the zinc sheet in the mixed solution is 1-12 hours. During this process, Mn 3 V 19 will self-assemble on the zinc sheet to form a Mn 3 V 19 interface film. The Mn 3 V 19 self-assembled film attached to the zinc sheet is uniform, dense, and has strong adhesion. After the zinc sheet is immersed in the mixed solution, it is dried under vacuum conditions at a temperature of 60-120 °C.

[0008] Compared with the prior art, the beneficial technical effects of the present invention are:

[0009] (1) The vanadium atoms with mixed valence states in the Mn 3 V 19 self-assembled film used in the present invention endows it with excellent redox ability. The unique cage-like porous structure provides sufficient transport channels for Zn 2+ , and can effectively guide the uniform deposition of Zn 2+ . This interface film also has the function of preventing the direct contact between the zinc anode and the electrolyte, thereby effectively avoiding serious corrosion and dendrite growth problems, and further improving the electrochemical stability and cycle life of the aqueous zinc-ion battery.

[0010] (2) The method for obtaining the Mn 3 V 19 self-assembled film in the present invention is simple in operation, low in cost, and environmentally friendly, which is conducive to large-scale promotion and commercial production. Brief Description of the Drawings

[0011] Figure 1 is a scanning electron microscope image of the surface of the zinc anode after 50 cycles of a symmetric battery assembled with a blank zinc sheet and zinc sheets with an attached Mn 3 V 19 interface film used in Examples 1-3 at a current density of 10 mA cm -2 and a deposition amount of 2 mAh cm -2 .

[0012] Figure 2 is for a zinc symmetric battery assembled with a common blank zinc sheet and a zinc sheet with an attached Mn 3 V 19 interface film used in Example 1 at 5 mA cm -2 , 2 mAh cm -2Time-voltage curve under conditions;

[0013] Figure 3 For Example 1, the full cell assembled with a common blank zinc sheet and a zinc sheet with an attached Mn 3 V 19 interface film at a current density of 3 Ag -1 cycle condition. Detailed implementation manners

[0014] The following further describes in detail the specific implementation manners of the present invention in conjunction with the accompanying drawings. For the experimental methods without specific conditions indicated in the examples, they are usually carried out according to the conventional conditions and the conditions described in the manuals, or according to the conditions recommended by the manufacturers. The reagents used are all commercially available.

[0015] Example 1:

[0016] Dissolve 0.026 g of Mn 3 V 19 polyoxometalate cluster crystals in 10 mL of N,N-dimethylformamide organic solution, and stir for 12 hours to obtain a 1 mmol L -1 Mn 3 V 19 -N,N-dimethylformamide mixed solution. Immerse the treated zinc sheet in the above-obtained mixed solution for 12 hours, and dry it in a vacuum oven at 60 °C to obtain a zinc sheet with an attached Mn 3 V 19 interface film. Dissolve 2.8 g of zinc sulfate heptahydrate in 10 mL of ultrapure water, stir and dissolve to prepare a 1 mol L -1 zinc sulfate aqueous solution.

[0017] Use the above-prepared zinc sheet and zinc sulfate electrolyte to assemble a zinc symmetric battery. The zinc ion battery in this example consists of a pair of metal zinc sheets, an electrolyte, and a separator. The separator is a glass fiber separator, and the button cell is assembled in air.

[0018] The electrochemical test of the zinc symmetric battery in this example is carried out on a LAND test system, and the test temperature is kept constant at 25 °C.

[0019] As Figure 1 (a) shows the surface of the zinc ion battery electrode after cycling 50 weeks at a current density of 10 mA cm -1 using a common zinc sheet and a 1 mol L -2 zinc sulfate electrolyte. It can be seen from the figure that there are a large number of zinc dendrites on the electrode surface.

[0020] As Figure 1 (b) shows the use of a zinc sheet with an attached Mn 3 V 19The zinc sheet of the interfacial film and 1 mol L -1 zinc sulfate electrolyte after 50 cycles at a current density of 10 mA cm -2 on the surface of the zinc-ion battery electrode. It can be seen from the figure that the electrode surface is flat and smooth, and no zinc dendrites are generated.

[0021] Electrochemical performance tests were carried out on zinc symmetric batteries assembled with blank zinc sheets and zinc sheets with Mn 3 V 19 interfacial film. The electrolyte was 1 mol L -1 zinc sulfate solution, the current density was 5 mA cm -2 , and the deposition amount was 2 mAh cm -2 .

[0022] As Figure 2 shown, compared with the blank zinc sheet, the zinc symmetric battery assembled with the zinc sheet with Mn 3 V 19 interfacial film exhibits more excellent cycling performance, and its cycle life can be up to 500 hours.

[0023] The active material of the positive electrode material of the zinc-ion battery was prepared by the following method:

[0024] (1) Dissolve 1 g of V 2 O 5 in 15 mL of water, add 1.8 g of NaCl, and stir for 72 hours. Filter, wash, and dry.

[0025] (2) Grind the dried positive electrode material into powder, mix it evenly with acetylene black and polytetrafluoroethylene in a ratio of 7:2:1, prepare a slurry and coat it on a 0.02 mm thick titanium foil, and vacuum dry it at 60 °C for 12 hours to obtain the positive electrode material of the zinc-ion battery.

[0026] The zinc-ion battery of this embodiment was assembled from the above positive electrode material, electrolyte, separator, and negative electrode material. The negative electrode material was a metal blank zinc sheet and a zinc sheet with Mn 3 V 19 interfacial film. The separator was glass fiber, and the button battery was assembled in air.

[0027] The electrochemical test of the zinc symmetric battery of this embodiment was carried out on a LAND test system. The test temperature was kept constant at 25 °C, and the voltage range was set to 0.2 V - 1.6 V.

[0028] As Figure 3 shown for the full battery assembled with a common blank zinc sheet and the zinc sheet with Mn 3 V 19 interfacial film of this embodiment at 3 A g -1Under the condition of a certain current density, for the zinc-ion battery assembled with a common blank zinc sheet, the capacity decays rapidly during cycling. After 500 cycles, the capacity only remains at 77.1 mAh g -1 , and the capacity retention rate is only 36.8%. For the zinc-ion battery assembled with the zinc sheet attached with the Mn 3 V 19 interface film in this example, it still has a high specific capacity of 117.2 mAh g -1 and a capacity retention rate of 59.6% after 500 cycles. It can be seen that the Mn 3 V 19 interface film of the present invention has a significant protective effect on the long cycling process of the battery, further enhancing the cycle life of the battery.

[0029] Example 2:

[0030] Dissolve 0.053 g of Mn 3 V 19 polyoxometalate cluster crystals in 10 mL of N,N-dimethylformamide organic solution, and stir for 12 hours to obtain a 2 mmol L -1 Mn 3 V 19 -N,N-dimethylformamide mixed solution. Immerse the treated zinc sheet in the above-obtained mixed solution for 12 hours, and dry it in a vacuum oven at 60 °C to obtain a zinc sheet attached with the Mn 3 V 19 interface film. Dissolve 2.8 g of zinc sulfate heptahydrate in 10 mL of ultrapure water, and stir to dissolve it to prepare a 1 mol L -1 aqueous zinc sulfate solution.

[0031] Use the above-prepared zinc sheet and zinc sulfate electrolyte to assemble a zinc symmetric battery. The zinc-ion battery in this example consists of a pair of metal zinc sheets, an electrolyte, and a separator. The separator is a glass fiber separator, and the button battery is assembled in air.

[0032] The electrochemical test of the zinc symmetric battery in this example is carried out on a LAND test system, and the test temperature is kept constant at 25 °C.

[0033] Example 3:

[0034] Dissolve 0.013 g of Mn 3 V 19 polyoxometalate cluster electrolyte additive crystals in 10 mL of N,N-dimethylformamide organic solution, and stir for 12 hours to obtain a 0.05 mmol L -1 Mn 3 V 19-N,N-dimethylformamide mixed solution. Immerse the treated zinc sheet in the above-obtained mixed solution for 12 hours, and dry it in a vacuum oven at 60 °C to obtain a zinc sheet with a Mn 3 V 19 interface film. Dissolve 2.8 g of zinc sulfate heptahydrate in 10 mL of ultrapure water, stir and dissolve to prepare a 1 mol L -1 aqueous zinc sulfate solution.

[0035] Use the above-prepared zinc sheet and zinc sulfate electrolyte to assemble a zinc symmetric battery. The zinc ion battery in this example consists of a pair of metal zinc sheets, an electrolyte, and a separator. The separator is a glass fiber separator, and the button battery is assembled in the air.

[0036] The electrochemical test of the zinc symmetric battery in this example is carried out on a LAND test system, and the test temperature is kept constant at 25 °C.

[0037] For the Mn prepared in Examples 2-3 3 V 19 The self-assembled film was tested according to the test method of Example 1. The experimental results were close to those of Example 1. The assembled zinc symmetric battery had higher cycle stability than the ordinary blank zinc sheet in Example 1. The zinc / zinc symmetric battery assembled with the zinc sheet with a Mn 3 V 19 self-interface film was relatively flat on the surface after cycling, and the size of zinc dendrites was significantly reduced.

[0038] Although the specific embodiments of the present invention have been described above, those skilled in the art should understand that these are only examples. Various changes or modifications can be made to these embodiments without departing from the principle and essence of the present invention. The protection scope of the present invention is only defined by the appended claims.

Claims

1. A method for self-assembly of Mn3V on the surface of zinc negative electrode 19 The scheme of the interfacial membrane and the zinc ions constructed based on this scheme.

2. The zinc negative electrode according to claim 1, characterized in that The negative electrode is any one of zinc sheet, zinc powder, foamed zinc and zinc alloy material.

3. The self-assembled Mn3V according to claim 1 19 An interfacial film, characterized in that The Mn3V 19 The self-assembled film is formed by 19 The polyacid crystals are dissolved in an organic solvent, and the zinc flakes are immersed in the solution to self-assemble into Mn3V 19 Interface membrane.

4. The zinc ion battery according to claim 1, characterized in that It includes a positive electrode, a negative electrode, an electrolyte and a separator between the positive and negative electrodes.

5. The positive electrode material according to claim 4 includes any one of V2O5, VS2, MoS2, WS2, MnS, MnO2, Na3V2(PO4)3, and elemental sulfur.

6. The negative electrode according to claim 4 is any one of zinc sheet, zinc powder, foamed zinc and zinc alloy material.

7. The electrolyte according to claim 4 is an aqueous solution of a soluble zinc salt.

8. The diaphragm according to claim 4, which is a glass fiber diaphragm.

Images