A zinc-ion battery negative electrode and its preparation method and zinc-ion battery

Abstract

This invention discloses a zinc-ion battery anode, its preparation method, and the zinc-ion battery itself. The zinc-ion battery anode is obtained by heat-treating zinc foil in a modifier. The modifier is any one or a combination of at least two of ammonium hexafluorosilicate, ammonium hexafluorophosphate, ammonium fluoride, potassium hexafluorosilicate, sodium hexafluorosilicate, sodium hexafluorophosphate, and potassium hexafluorophosphate. The heat treatment temperature is 60-80℃. The modifier can form a protective layer on the zinc foil surface, inhibiting corrosion and regulating zinc ion transport and deposition, thus significantly improving the electrochemical performance of the zinc-ion battery. The prepared zinc-ion battery exhibits excellent cycle life, long cycle stability, and high discharge specific capacity.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, and more specifically, relates to a zinc-ion battery negative electrode, its preparation method, and a zinc-ion battery. Background Technology

[0002] With the rapid development of the global economy, serious problems such as fossil fuel shortages and environmental pollution have become increasingly prominent. Developing green energy storage systems to replace or partially replace traditional fossil fuels has become a mainstream research focus. Metal-ion batteries, such as lithium, sodium, zinc, magnesium, calcium, and aluminum, have received widespread attention in the field of electrochemical energy storage systems. In particular, lithium-ion batteries are widely used in the market as portable energy storage devices due to their high energy density, light weight, negligible memory effect, and long cycle life. However, lithium-ion batteries are expensive and pose safety risks due to thermal runaway of organic electrolytes. In contrast, aqueous zinc-ion batteries are considered a promising large-scale energy storage technology due to their inherent safety and the unique advantages of zinc metal anodes. These include high theoretical capacity (820 mAh g⁻¹). -1 The zinc anode exhibits high efficiency and low redox potential (-0.76 V vs. SHE). Unfortunately, corrosion, hydrogen evolution reaction, interfacial parasitic reactions, and dendrite growth during the zinc plating / stripping process hinder commercial applications, resulting in low utilization, low coulombic efficiency, and short cycle life. Therefore, developing effective strategies to address these issues is crucial for the practical application of aqueous zinc-ion batteries.

[0003] To address the aforementioned problems associated with zinc metal, researchers have undertaken extensive work, including interface modification, electrolyte optimization, and separator modification. Due to the characteristics of zinc-ion batteries (directly using zinc foil as the negative electrode), directly modifying the zinc negative electrode to obtain a long-life, high-coulombic-efficiency zinc-ion battery is a simple and effective method. Currently, the modification of zinc negative electrodes typically involves forming a protective layer on the zinc surface using metal oxides and / or polymers, a relatively cumbersome process. Therefore, researching a simplified modification process for zinc-ion battery negative electrodes is of great significance for their practical application. Summary of the Invention

[0004] The purpose of this invention is to provide a zinc-ion battery anode, its preparation method, and a zinc-ion battery. The modified anode can slow down corrosion, induce uniform zinc ion deposition, and inhibit zinc dendrite growth. The assembled zinc-ion battery has excellent cycle life, long cycle stability, and better coulombic efficiency.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A zinc-ion battery negative electrode, wherein the negative electrode is obtained by forming a protective layer from zinc foil in a modifier solution; the modifier is any one or a combination of at least two of ammonium hexafluorosilicate, ammonium hexafluorophosphate, ammonium fluoride, potassium hexafluorosilicate, sodium hexafluorosilicate, sodium hexafluorophosphate, and potassium hexafluorophosphate.

[0007] In this invention, the modifier forms a solid electrolyte interface layer rich in ZnF2 and other inorganic substances on the surface of the zinc foil as a protective layer, thereby improving battery performance, inhibiting the occurrence of side reactions, and extending battery cycle life.

[0008] Furthermore, the zinc foil can form a protective layer more quickly by heat treatment or electrostatic treatment in a modifier solution; the heat treatment temperature is 60-80℃.

[0009] The electrochemical treatment in this invention does not limit the current or voltage, as long as a solid electrolyte interface layer rich in ZnF2 and other inorganic substances can be formed on the zinc foil. In some embodiments, a modifier can also be added to the electrolyte to form a protective layer on the zinc negative electrode surface during battery operation.

[0010] Furthermore, the modifier is ammonium hexafluorosilicate.

[0011] Furthermore, the zinc foil thickness is 10-100 μm.

[0012] Further, the solvent of the modifier solution includes any one or a combination of at least two of the following: deionized water, ethylene carbonate, acetonitrile, trimethyl phosphate, triethyl phosphate, methyl propionate, ethyl propionate, ethyl acetate, methyl ethyl carbonate, methyl formate, propylene carbonate, methyl acetate, triethylene glycol dimethyl ether, or dimethyl sulfoxide. Water is preferred.

[0013] Furthermore, the content of the modifier in the modifier solution is 0.5–10 wt%.

[0014] The above-mentioned method for preparing the negative electrode of a zinc-ion battery includes the following steps: placing zinc foil in a modifier solution to form a protective layer, wherein the modifier is any one or a combination of at least two of ammonium hexafluorosilicate, ammonium hexafluorophosphate, ammonium fluoride, potassium hexafluorosilicate, sodium hexafluorosilicate, sodium hexafluorophosphate, and potassium hexafluorophosphate.

[0015] A zinc-ion battery includes the aforementioned negative electrode, electrolyte, and positive electrode.

[0016] In this invention, the type of zinc-ion battery is not limited; it can be an aqueous zinc-ion battery, comprising a positive electrode, the aforementioned negative electrode, a separator, and an electrolyte. The positive electrode is vanadium pentoxide or vanadium hydroxyoxide, or other vanadium and manganese oxide positive electrode materials. The separator is a glass fiber membrane, and the electrolyte is a 2 mol / L ZnSO4 solution.

[0017] In this invention, the zinc-ion battery can also be a zinc symmetric battery, wherein both the positive electrode and the negative electrode are the negative electrode described above.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] The zinc-ion battery anode of the present invention has extremely high stability. The protective layer formed on the surface of the zinc foil can inhibit the corrosion of zinc metal, reduce by-products, and extend the cycle life of the zinc-ion battery, which is of great significance for promoting its application in the field of large-scale energy storage. Attached Figure Description

[0020] Figure 1 This is a SEM image of the zinc anode prepared in Example 1 of this invention.

[0021] Figure 2 These are rate cycle performance test graphs of zinc symmetric batteries assembled with zinc anodes prepared in Example 1 and Comparative Example 1 of this invention.

[0022] Figure 3 This is a coulombic efficiency diagram of the half-cell assembled with zinc anodes prepared in Example 1 and Comparative Example 1 of this invention.

[0023] Figure 4 This is a rate cycle performance test diagram of the full cell assembled with zinc anodes prepared in Example 1 and Comparative Example 1 of this invention.

[0024] Figure 5 This is a coulombic efficiency diagram of the assembled half-cells with zinc anodes prepared in Example 5 and Comparative Example 1 of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in further detail below with reference to embodiments, but the embodiments of this invention are not limited thereto. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. It should be noted that, unless otherwise specified, the reagents and other materials used in this embodiment are all common commercially available products.

[0026] Example 1

[0027] A zinc negative electrode heat-treated with ammonium hexafluorosilicate is prepared by the following steps:

[0028] 3g of ammonium hexafluorosilicate was added to deionized water to prepare a 300ml solution. The solution was then ultrasonically degassed at room temperature to obtain a 1wt% ammonium hexafluorosilicate aqueous solution. A 100μm thick zinc foil was polished with 500-grit and 2000-grit sandpaper, cleaned with alcohol, and placed in the 1wt% ammonium hexafluorosilicate aqueous solution. It was ultrasonically degassed for 15 seconds, then placed in a constant-temperature oil bath at 60℃ for 1 minute. After removal, it was rinsed with deionized water and dried under an infrared lamp for 1 hour. Finally, it was transferred to a vacuum drying oven and dried overnight. The dried foil was then cut into round pieces for later use. Figure 1 As shown in the SEM image, an artificial solid electrolyte interface layer of about 4 μm was uniformly formed on the zinc anode under the action of ammonium hexafluorosilicate.

[0029] Example 2

[0030] Compared with Example 1, the difference is that the modified zinc foil was prepared by treating it in an oil bath at 60°C for 5 minutes.

[0031] Example 3

[0032] Compared with Example 1, the difference is that 6g of ammonium hexafluorosilicate was added to deionized water to prepare a 300ml solution, and modified zinc foil was prepared by heat treatment with 2wt% ammonium hexafluorosilicate aqueous solution.

[0033] Example 4

[0034] Compared with Example 1, the difference is that the zinc foil is placed in a constant temperature oil bath and treated at 80°C for 1 minute to prepare the modified zinc foil under the heat treatment condition of 80°C.

[0035] Example 5

[0036] 6g of ammonium hexafluorosilicate was added as an additive to 300ml of 2M ZnSO4 electrolyte. A 100μm thick zinc foil was polished with 500-grit and 2000-grit sandpaper, cleaned with alcohol, and used as the positive and negative electrodes. After passing an electric current for 1 minute, a zinc negative electrode with a protective layer was obtained.

[0037] Comparative Example 1

[0038] Compared with Example 1, the difference is that the zinc foil was not heat-treated with ammonium hexafluorosilicate aqueous solution, and untreated zinc foil was prepared.

[0039] Performance testing

[0040] The assembly of an aqueous zinc-ion battery follows this sequence: positive electrode shell, positive electrode material, separator, electrolyte, negative electrode, and negative electrode shell. For zinc symmetric batteries, both electrodes on either side of the separator are treated zinc foil; for Zn / / VOOH batteries, the positive electrode material is VOOH, the negative electrode is zinc foil heat-treated with a 1% ammonium hexafluorosilicate aqueous solution, and the electrolyte is 180 μL.

[0041] Figure 2 The zinc symmetric cells assembled with zinc anodes prepared in Example 1 and Comparative Example 1 are shown at 0.2, 0.5, 1, 2, 3, 5, and 10 mA cm⁻¹. -2 Current density and 1mAh cm -2 The rate cycling performance diagram is shown for the area capacity. In Example 1, the limiting current of the zinc symmetric cell can reach 10 mA cm⁻¹. -2 Furthermore, the battery exhibits a stable voltage curve overall. In contrast, in Comparative Example 1, at 2mA cm... -2 Current density and 1mAh cm -2 Under the conditions of deposition areal capacity testing, the zinc symmetric cell already experienced a short circuit, exhibiting an unstable voltage curve. This further demonstrates that the zinc electrode obtained by heat treatment with ammonium hexafluorosilicate can effectively increase the rate cycle performance of aqueous zinc-ion batteries.

[0042] Figure 3 The zinc-copper half-cells assembled with zinc anodes as described in Example 1 and Comparative Example 1 were used at a current density of 1 mA / cm². -2 and area capacity of 1mAh cm -2 The coulombic efficiency diagram under test conditions, and the analysis of the results of Example 1 and Comparative Example 1, show that the zinc electrode obtained by heat treatment with ammonium hexafluorosilicate has a higher coulombic efficiency than the blank zinc foil. This further illustrates that the zinc electrode obtained by heat treatment with ammonium hexafluorosilicate can effectively reduce the occurrence of side reactions in zinc-ion batteries and greatly extend the cycle life of zinc-ion batteries.

[0043] Figure 4 The aqueous zinc-ion full cells prepared using Example 1 and Comparative Example 1 as negative electrodes and VOOH as positive electrodes are demonstrated in 0.1, 0.2, 0.3, 0.5, 1, 2, 3, and 5 Ag values. -1 The rate cycling performance at the specified current density is shown in the figure. It can be clearly observed from the figure that the full cell assembled with the zinc anode obtained by heat treatment of ammonium hexafluorosilicate exhibits a higher overall discharge specific capacity.

[0044] Figure 5 The zinc-copper half-cell assembled using the electrolyte prepared in Example 5 or Comparative Example 1 (using 2M ZnSO4 as the electrolyte) was demonstrated at a current density of 1 mA cm⁻¹. -2 and area capacity of 1mAh cm -2The coulombic efficiency diagram under test conditions, and the analysis of the results of Example 5 and Comparative Example 1, show that the electrolyte with added ammonium hexafluorosilicate has a higher coulombic efficiency and a longer cycle life than the 2M ZnSO4 electrolyte. This further illustrates that the electrolyte with added ammonium hexafluorosilicate forms a protective layer on the zinc anode under the action of an electric field, which can effectively reduce the occurrence of side reactions in zinc-ion batteries and greatly extend the cycle life of zinc-ion batteries.

[0045] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a zinc-ion battery negative electrode, characterized in that, The negative electrode is obtained by heat-treating zinc foil in a modifier solution for 1 minute to form a protective layer; the modifier is ammonium hexafluorosilicate; the heat treatment temperature is 60-80℃; the modifier forms a 4μm solid electrolyte interface layer rich in ZnF2 and other inorganic substances on the surface of the zinc foil as a protective layer.

2. The preparation method according to claim 1, characterized in that, The solvent of the modifier solution includes any one or a combination of at least two of the following: deionized water, ethylene carbonate, acetonitrile, trimethyl phosphate, triethyl phosphate, methyl propionate, ethyl propionate, ethyl acetate, methyl ethyl carbonate, methyl formate, propylene carbonate, methyl acetate, triethylene glycol dimethyl ether, or dimethyl sulfoxide.

3. The preparation method according to claim 1, characterized in that, The modifier content in the modifier solution is 0.5~10 wt%.

4. A zinc-ion battery, characterized in that, Includes the negative electrode prepared by the preparation method according to any one of claims 1-3.

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