Method for stabilizing zinc negative electrode of aqueous zinc ion battery

Abstract

The invention discloses a method for stabilizing a zinc negative electrode of a water-based zinc ion battery, and belongs to the technical field of water-based zinc ion batteries, dipentaerythritol (DPE) is coated on the surface of a zinc sheet to form a coating, the thickness of the coating is 10-30 microns, the coating is used as the negative electrode of the water-based zinc ion battery, the DPE layer continuously plays a role in the cycle period of the water-based zinc ion battery, and the zinc negative electrode of the water-based zinc ion battery is stabilized. Formation induction and controllable growth of basic zinc sulfate (ZHS) are realized. Furthermore, a layer of uniform ZHS can be regularly arranged between the DPE and the Zn interlayer and forms a compact solid electrolyte interface (SEI), finally, an organic / inorganic double-interface layer (DPE / ZHS at Zn) is formed, the double-interface layer not only can effectively inhibit the growth of dendritic crystals, but also can improve the interface stability of the zinc negative electrode and provide brand-new theoretical guidance for the modification of the zinc negative electrode, and through the mode, the zinc negative electrode has a good application prospect. The stability problem of the zinc negative electrode is expected to be fundamentally solved, and the commercialization process of the water-based zinc ion battery is promoted.

Description

Technical Field

[0001] The invention belongs to the technical field of aqueous zinc ion batteries, and in particular relates to a method for stabilizing a zinc negative electrode of an aqueous zinc ion battery. Background Art

[0002] Aqueous zinc ion batteries (AZIBs) are considered to be a promising large-scale energy storage technology due to their low cost, high safety, and high volumetric energy density. However, the stability of zinc metal anodes has always been a key bottleneck restricting their commercial application. In aqueous electrolytes, zinc anodes are prone to hydrogen evolution reaction (HER) during charge and discharge, resulting in the formation of byproducts such as basic zinc sulfate (ZHS). These byproducts will destroy the uniformity of electron and ion distribution at the zinc anode interface, thereby inducing dendrite growth, ultimately leading to battery short circuits, shortened cycle life, and other problems.

[0003] In order to solve the stability problem of zinc anode, researchers have tried a variety of methods, including surface modification, structural optimization, electrolyte engineering and diaphragm design. For example, by coating a protective film on the surface of zinc anode or using a three-dimensional current collector as a pre-deposited zinc substrate, the growth of dendrites can be effectively inhibited. In addition, optimizing the electrolyte composition, such as introducing highly concentrated salt electrolytes (WISEs) or hydrated eutectic electrolytes (HEEs), can broaden the electrochemical stability window of the electrolyte and inhibit the occurrence of side reactions. However, although these methods have made some progress, they have not fundamentally solved the problem of the generation of basic zinc sulfate by-products. At the same time, due to its high ionic conductivity and low electronic conductivity, ZHS is an ideal candidate material for materials that can stabilize the zinc anode interface. Therefore, if the controllable growth of ZHS can be controlled, then forming a uniform and dense ZHS layer on the zinc anode is a measure to turn harm into benefit.

[0004] At present, the construction of a dense ZHS layer on the surface of zinc anode is mainly achieved through electrolyte additives. However, electrolyte additives tend to increase the polarization of the battery and affect the charge and discharge efficiency. In addition, during the charge and discharge process of the battery, chemical corrosion reactions are prone to occur on the surface of the zinc anode. Therefore, how to control the growth of ZHS while avoiding the negative effects of electrolyte additives remains a daunting challenge. Summary of the invention

[0005] In order to solve the above technical problems, the present invention proposes a method for stabilizing the zinc negative electrode of an aqueous zinc ion battery.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The invention provides a method for stabilizing the zinc negative electrode of an aqueous zinc ion battery. Dipentaerythritol (DPE) is coated on the surface of a zinc sheet to form a coating, the thickness of the coating is 10 to 30 μm, and the coating is used as the negative electrode of the aqueous zinc ion battery.

[0008] The structural formula of dipentaerythritol is

[0009] The present invention coats dipentaerythritol (DPE) on the surface of a zinc sheet to form a coating, which is then used as the negative electrode of an aqueous zinc ion battery. During the cycle of the aqueous zinc ion battery, the DPE layer continues to play a role, achieving the formation induction and controllable growth of basic zinc sulfate (ZHS). Furthermore, a uniform layer of ZHS will be regularly arranged between the DPE and Zn interlayers and form a tight solid electrolyte interface (SEI), and finally form an organic / inorganic double interface layer (DPE / ZHS@Zn). This double interface layer can not only effectively inhibit the growth of dendrites, but also improve the interface stability of the zinc negative electrode, providing a new theoretical guidance for the modification of the zinc negative electrode. In this way, it is expected to fundamentally solve the stability problem of the zinc negative electrode and promote the commercialization of aqueous zinc ion batteries.

[0010] Furthermore, the method for stabilizing the zinc negative electrode of an aqueous zinc ion battery comprises the following steps:

[0011] First, DPE and polyvinylidene fluoride (PVDF) are mixed, and then N-methylpyrrolidone (NMP) is added, and the mixture is mixed evenly to obtain a slurry;

[0012] The slurry is coated on the surface of the zinc sheet, and after drying, a water-based coated electrode (DPE@Zn) is obtained;

[0013] The aqueous zinc ion battery is assembled by using the aqueous electrode coated with the coating as a negative electrode.

[0014] Further, the mass ratio of dipentaerythritol to polyvinylidene fluoride is (7-9):(1-3). Exemplarily, the mass ratio of dipentaerythritol to polyvinylidene fluoride is 7:3, 8:2 or 9:1, preferably the mass ratio of dipentaerythritol to polyvinylidene fluoride is 9:1.

[0015] Furthermore, before coating the slurry on the surface of the zinc sheet, the zinc sheet is pretreated: one side of the zinc sheet is polished smooth with sandpaper, and then rinsed with water and anhydrous ethanol in sequence, and dried.

[0016] Exemplarily, before coating the slurry on the surface of the zinc sheet, the steps of pre-treating the zinc sheet are as follows: select a 0.05 mm thick zinc sheet, polish one side of the zinc sheet smooth with 2000 mesh sandpaper, then rinse with deionized water 3 times, and finally rinse with ethanol 3 times, dry and set aside. The purpose of the above treatment is to remove the oxide layer and surface impurities generated by the zinc sheet in the air.

[0017] Exemplarily, the coating has a thickness of 10 μm, 15 μm, 20 μm, 25 μm or 30 μm.

[0018] When the aqueous zinc ion battery is assembled by using the aqueous coated electrode as a negative electrode, the battery type can be a symmetrical battery or an asymmetrical battery.

[0019] Exemplarily, when assembling a symmetrical battery, the assembly steps are as follows: DPE@Zn is cut into electrode sheets with a diameter of 12 mm using a slicer. An electrode sheet is placed in the negative electrode shell, ensuring that one side of the coating contacts the glass fiber diaphragm, and then the glass fiber diaphragm is placed, and 100 μL of a 2 mol / L zinc sulfate solution is dripped in as an electrolyte to completely wet the glass fiber diaphragm, and then another electrode sheet is placed on top of the glass fiber diaphragm as a zinc negative electrode sheet, and the coating side is also contacted with the glass fiber diaphragm, and then the gasket and shrapnel are placed, and finally the positive electrode shell is buckled, and the battery is packaged using a battery packaging machine, and a modified zinc negative electrode aqueous zinc ion symmetrical button battery is obtained, which is marked as DPE@Zn / / DPE@Zn symmetrical battery.

[0020] At present, constructing a polyhydroxy coating on the zinc anode can effectively achieve the desolvation of solvated zinc ions (through hydrogen bonding between hydroxyl groups), thereby avoiding side reactions caused by water. However, since the standard potential of zinc metal is -0.76V, the hydrogen evolution reaction cannot be completely avoided, which leads to the formation of byproducts (such as basic zinc sulfate, ZHS). However, ZHS is an ideal material that can stabilize the zinc anode interface. Therefore, if the growth of ZHS can be regulated to form a protective layer in situ, the effect of turning waste into treasure can be achieved. Although in the prior art, the construction of a dense ZHS layer on the zinc anode is mainly achieved by electrolyte additives. However, electrolyte additives often increase the polarization degree of the battery and affect the charge and discharge efficiency. In addition, during the charge and discharge process of the battery, chemical corrosion reactions are prone to occur on the surface of the zinc anode. In order to solve the above problems, the present invention pre-coats a layer of dipentaerythritol (DPE) coating on the surface of the zinc anode, thereby realizing the controllable formation and growth of ZHS. First, DPE is a polyhydroxy compound that can continuously and effectively protect the zinc anode before inducing the formation of ZHS to prevent corrosion of the zinc anode. Secondly, DPE can induce the horizontal dense growth of ZHS and form an in-situ protective layer for the zinc anode. Finally, ZHS is also a polyhydroxy substance, which can further promote the desolvation process. In addition, this in-situ formed dynamic protective layer can also avoid the problem of DPE coating failure due to volume changes in long-term cycles. The double interface layer formed by this strategy can not only effectively inhibit the growth of dendrites, but also improve the interfacial stability of the zinc negative electrode, providing new theoretical guidance for the modification of the zinc negative electrode. Through this strategy, it is expected to fundamentally solve the stability problem of the zinc negative electrode and promote the commercialization of aqueous zinc-ion batteries.

[0021] Compared with the prior art, the present invention has the following advantages and technical effects:

[0022] The invention coats dipentaerythritol (DPE) on the surface of a zinc sheet to form a coating, which is then used as the negative electrode of an aqueous zinc ion battery. During the zinc deposition process, the coated DPE layer is hydrolyzed, resulting in pH fluctuations at the interface of the zinc negative electrode, thereby inducing basic zinc sulfate (ZHS) to stack in parallel at the interface to form a dense protective layer. The generation of ZHS can significantly alleviate the side reaction between the zinc negative electrode and water. A uniform layer of ZHS is regularly arranged between the DPE and Zn interlayers to form a compact solid electrolyte interface (SEI), and finally an organic / inorganic double interface layer (DPE / ZHS@Zn) is formed. The organic / inorganic double interface layer can increase the hydrogen evolution overpotential, effectively alleviate the hydrogen evolution side reaction, and protect the zinc anode. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0024] Figure 1 a is a scanning electron microscope (SEM) image of Bare Zn in Comparative Example 1, b is a SEM image of DPE@Zn in Example 1, and c is a SEM image of ZHS@Zn in Example 1;

[0025] Figure 2 a is the X-ray diffraction (XRD) diagram of Bare Zn in Comparative Example 1, DPE@Zn in Example 1, and DPE / ZHS@Zn in Example 1; b is the SEM diagram of DPE / ZHS@Zn in Example 1 and the corresponding energy spectrum analysis (EDS) diagram; c is the specific content ratio of each element in b;

[0026] Figure 3 a is a linear sweep voltammetry (LSV) diagram of Bare Zn in Comparative Example 1 and DPE / ZHS@Zn in Example 1, b is an LSV diagram of Bare Cu and DPE / ZHS@Cu (the preparation method of DPE / ZHS@Cu is the same as that of DPE / ZHS@Zn in Example 1, and the original zinc sheet is replaced with an equivalent copper sheet), and c is an LSV diagram of Bare Ti and DPE / ZHS@Ti (the preparation method of DPE / ZHS@Ti is the same as that of DPE / ZHS@Zn in Example 1, and the original zinc sheet is replaced with an equivalent titanium sheet);

[0027] Figure 4 It is the Tafel curve of Bare Zn in Comparative Example 1 and DPE / ZHS@Zn in Example 1;

[0028] Figure 5 a is the chronoamperometry graph of Bare Zn in Comparative Example 1 and DPE / ZHS@Zn in Example 1, b is the final optical microscope graph of Bare Zn, and c is the final optical microscope graph of DPE / ZHS@Zn;

[0029] Figure 6 Cycling curves of DPE / ZHS@Zn symmetric battery and Bare Zn symmetric battery;

[0030] Figure 7 Cycling curves of DPE / ZHS@Zn||DPE / ZHS@Cu half-cell and Bare Zn||Bare Cu(Zn||Cu) half-cell

[0031] Figure 8 This is the cycle curve of the aqueous zinc ion symmetric button battery in Comparative Example 2. DETAILED DESCRIPTION

[0032] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0033] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0034] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0035] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0036] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0037] The embodiment of the present invention provides a method for stabilizing the zinc negative electrode of an aqueous zinc ion battery, wherein dipentaerythritol (DPE, ) is coated on the surface of the zinc sheet to form a coating with a thickness of 10 to 30 μm, which is used as the negative electrode of the aqueous zinc ion battery.

[0038] The present invention coats dipentaerythritol (DPE) on the surface of a zinc sheet to form a coating, which is then used as the negative electrode of an aqueous zinc ion battery. During the cycle of the aqueous zinc ion battery, the DPE layer continues to play a role, achieving the formation induction and controllable growth of basic zinc sulfate (ZHS). Furthermore, a uniform layer of ZHS will be regularly arranged between the DPE and Zn interlayers and form a tight solid electrolyte interface (SEI), and finally form an organic / inorganic double interface layer (DPE / ZHS@Zn). This double interface layer can not only effectively inhibit the growth of dendrites, but also improve the interface stability of the zinc negative electrode, providing a new theoretical guidance for the modification of the zinc negative electrode. In this way, it is expected to fundamentally solve the stability problem of the zinc negative electrode and promote the commercialization of aqueous zinc ion batteries.

[0039] In some embodiments of the present invention, a method for stabilizing a zinc negative electrode of an aqueous zinc ion battery comprises the following steps:

[0040] First, DPE and polyvinylidene fluoride (PVDF) are mixed, and then N-methylpyrrolidone (NMP) is added, and the mixture is mixed evenly to obtain a slurry;

[0041] The slurry was coated on the surface of zinc sheet and dried to obtain a water-based coated electrode (DPE@Zn);

[0042] The aqueous zinc-ion battery is assembled by using the aqueous coated electrode as the negative electrode.

[0043] In some embodiments of the present invention, the mass ratio of dipentaerythritol to polyvinylidene fluoride is (7-9):(1-3). Exemplarily, the mass ratio of dipentaerythritol to polyvinylidene fluoride is 7:3, 8:2 or 9:1, and preferably the mass ratio of dipentaerythritol to polyvinylidene fluoride is 9:1.

[0044] In some embodiments of the present invention, before the slurry is coated on the surface of the zinc sheet, the zinc sheet is pretreated: one side of the zinc sheet is polished smooth with sandpaper, and then rinsed with water and anhydrous ethanol in sequence, and dried.

[0045] In some preferred embodiments of the present invention, before the slurry is coated on the surface of the zinc sheet, the steps of pre-treating the zinc sheet are as follows: select a 0.05 mm thick zinc sheet, polish one side of the zinc sheet with 2000 mesh sandpaper, then rinse it with deionized water for 3 times, and finally rinse it with ethanol for 3 times, and then dry it for use. The purpose of the above treatment is to remove the oxide layer and surface impurities generated by the zinc sheet in the air.

[0046] In some embodiments of the present invention, the coating has a thickness of 10 μm, 15 μm, 20 μm, 25 μm or 30 μm.

[0047] When an aqueous zinc-ion battery is assembled by using the aqueous coated electrode as a negative electrode, the battery type can be a symmetrical battery or an asymmetrical battery.

[0048] In some embodiments of the present invention, when assembling a symmetrical battery, the assembly steps are as follows: DPE@Zn is cut into electrode sheets with a diameter of 12 mm using a slicer. An electrode sheet is placed in the negative electrode shell, ensuring that one side of the coating contacts the glass fiber diaphragm, and then the glass fiber diaphragm is placed, and 100 μL of a 2 mol / L zinc sulfate solution is dripped as an electrolyte to completely soak the glass fiber diaphragm, and then another electrode sheet is placed on top of the glass fiber diaphragm as a zinc negative electrode sheet, and the coating side is also contacted with the glass fiber diaphragm, and then a gasket and a spring are placed, and finally the positive electrode shell is buckled, and the battery is packaged using a battery packaging machine, and a modified zinc negative electrode aqueous zinc ion symmetrical button battery is obtained, which is marked as DPE@Zn / / DPE@Zn symmetrical battery.

[0049] At present, constructing a polyhydroxy coating on the zinc anode can effectively achieve the desolvation of solvated zinc ions (through hydrogen bonding between hydroxyl groups), thereby avoiding side reactions caused by water. However, since the standard potential of zinc metal is -0.76V, the hydrogen evolution reaction cannot be completely avoided, which leads to the formation of byproducts (such as basic zinc sulfate, ZHS). However, ZHS is an ideal material that can stabilize the zinc anode interface. Therefore, if the growth of ZHS can be regulated to form a protective layer in situ, the effect of turning waste into treasure can be achieved. Although in the prior art, the construction of a dense ZHS layer on the zinc anode is mainly achieved by electrolyte additives. However, electrolyte additives often increase the polarization degree of the battery and affect the charge and discharge efficiency. In addition, during the charge and discharge process of the battery, chemical corrosion reactions are prone to occur on the surface of the zinc anode. In order to solve the above problems, the present invention pre-coats a layer of dipentaerythritol (DPE) coating on the surface of the zinc anode, thereby realizing the controllable formation and growth of ZHS. First of all, DPE is a polyhydroxy compound that is almost insoluble in water, so it can continuously and effectively protect the zinc anode. Secondly, DPE can prevent the corrosion of zinc anode before inducing the formation of ZHS, while avoiding the adverse effects of other electrolyte additives. Finally, ZHS is also a polyhydroxy substance, which can further promote the desolvation process. In addition, this in-situ formed dynamic protective layer can also avoid the problem of DPE coating failure due to volume changes during long-term cycles. The double interface layer formed by this strategy can not only effectively inhibit the growth of dendrites, but also improve the interfacial stability of the zinc negative electrode, providing new theoretical guidance for the modification of the zinc negative electrode. Through this strategy, it is expected to fundamentally solve the stability problem of the zinc negative electrode and promote the commercialization of aqueous zinc-ion batteries.

[0050] The principle of the present invention is as follows: the present invention is a method for stabilizing aqueous zinc-ion batteries. Compared with lithium-ion batteries, the protection of the negative electrode is based on a completely different concept. Lithium-ion batteries use organic electrolytes, while zinc-ion batteries use aqueous electrolytes. Zinc-ion batteries will undergo water-induced side reactions during use, such as hydrogen evolution, corrosion, and the generation of byproduct ZHS. The present invention utilizes the principle that DPE is polyhydroxy, insoluble in water, and undergoes hydrolysis, to induce the formation of a solid ZHS protective layer, and finally forms an organic / inorganic double interface layer, which effectively protects the zinc negative electrode from being damaged by water-induced side reactions and prolongs the life of the aqueous zinc-ion battery.

[0051] The reagents used in the examples and comparative examples of the present invention are all purchased from commercial sources.

[0052] In the examples and comparative examples of the present invention, dipentaerythritol was purchased from Roan's Reagent; polyvinylidene fluoride (PVDF) was purchased from Dongguan Kelude Innovation Technology Co., Ltd.; and glass fiber diaphragm was purchased from Whatman.

[0053] It should be pointed out that the matters not described in detail in the present invention are conventional operating means in the art and are not the focus of the present invention. For example, the specific method of grinding is completed by conventional methods.

[0054] The technical solution of the present invention is further illustrated by the following embodiments.

[0055] Example 1

[0056] (1) Pretreatment of zinc sheet: Select a zinc sheet with a thickness of 0.05 mm, polish one side of the zinc sheet with 2000 grit sandpaper, then rinse it with deionized water for 3 times, and finally rinse it with ethanol for 3 times. After the above treatment, dry it and set it aside. The purpose of the above treatment is to remove the oxide layer and surface impurities generated by the zinc sheet in the air.

[0057] (2) Organic dipentaerythritol (DPE, 100 mg) and polyvinylidene fluoride (PVDF) were mixed at a mass ratio of 9:1, and then 15 drops of N-methylpyrrolidone (NMP) were added and mixed evenly in an agate mortar to obtain a slurry. The slurry was evenly coated on the surface of the zinc sheet with a blade, and the coating thickness was 20 μm. The zinc sheet was taken out and placed in a vacuum drying oven and dried at 60°C for 12 hours to prepare a coated electrode (DPE@Zn), wherein the specific structural formula of the organic DPE is shown below:

[0058]

[0059] (3) Assembling the battery: The DPE@Zn prepared in step (2) is cut into electrode sheets with a diameter of 12 mm using a slicer. An electrode sheet is placed in the negative electrode shell, ensuring that one side of the coating contacts the glass fiber separator, and then the glass fiber separator is placed, and 100 μL of a 2 mol / L zinc sulfate solution is dripped in as an electrolyte to completely soak the glass fiber separator, and then another electrode sheet is placed on top of the glass fiber separator as a zinc negative electrode sheet, and the coated side is also contacted with the glass fiber separator, and then a gasket and a spring are placed, and finally the positive electrode shell is buckled, and the battery is packaged using a battery packaging machine, and a modified zinc negative electrode aqueous zinc ion symmetrical button battery is obtained, which is marked as a DPE@Zn / / DPE@Zn symmetrical battery.

[0060] The DPE@Zn / / DPE@Zn symmetric battery was pre-cycled for 50 hours on a Xinwei battery tester. During this period, the DPE layer continued to play a role, achieving controllable formation and growth of basic zinc sulfate (ZHS). Then, a uniform layer of ZHS was regularly arranged between the DPE and Zn interlayers and formed a tight solid electrolyte interface (SEI), eventually forming an organic / inorganic dual interface (DPE / ZHS@Zn).

[0061] Example 2

[0062] The same as Example 1, except that in step (2), the mass ratio of DPE to PVDF is 8:2.

[0063] Example 3

[0064] The same as Example 1, except that in step (2), the mass ratio of DPE to PVDF is 7:3.

[0065] Example 4

[0066] Same as Example 1, except that the coating thickness in step (2) is 10 μm.

[0067] Example 5

[0068] Same as Example 1, except that the coating thickness in step (2) is 15 μm.

[0069] Example 6

[0070] Same as Example 1, except that the coating thickness in step (2) is 25 μm.

[0071] Example 7

[0072] Same as Example 1, except that the coating thickness in step (2) is 30 μm.

[0073] Comparative Example 1

[0074] The same as Example 1, the only difference is that the DPE@Zn electrode sheet is replaced with uncoated Zn (Bare Zn), and the electrode sheets are assembled to obtain an unmodified zinc negative electrode aqueous zinc ion symmetric button battery, which is marked as a Zn / / Zn symmetric battery.

[0075] Comparative Example 2

[0076] (1) Zinc sheet pretreatment: same as in Example 1;

[0077] (2) DPE (100 mg) and PVDF were mixed in a mass ratio of 9:1, and then 15 drops of NMP were added and mixed evenly in an agate mortar to obtain a slurry. The slurry was evenly coated on a glass fiber separator with a blade, and the coating thickness was 20 μm. The mixture was placed in a vacuum drying oven and dried at 60° C. for 12 h to obtain a treated glass fiber separator;

[0078] (3) Assembling the battery: Use a slicer to cut the pretreated zinc sheet into electrode sheets with a diameter of 12 mm. Place one electrode sheet in the negative electrode shell and then place the treated glass fiber separator. Drop 100 μL of 2 mol / L zinc sulfate solution as the electrolyte to completely soak the glass fiber separator. Then place another electrode sheet on top of the glass fiber separator as the zinc negative electrode sheet. Then place the gasket and shrapnel. Finally, buckle the positive electrode shell and use a battery packaging machine to package the battery. This will give an aqueous zinc ion symmetrical button battery.

[0079] In this comparative example, the DPE treatment of the separator did not have the same effect as the direct treatment of the zinc negative electrode. This is due to the insufficient contact between DPE and the zinc negative electrode. The use of DPE to treat the separator will cause the in-situ induced ZHS to grow less tightly, which not only cannot inhibit the further formation of ZHS, but also cannot form an effective protective layer, resulting in poor performance, and ultimately only less than 400h of performance ( Figure 8 ).

[0080] Taking Example 1 as an example, the effect of the double interface layer formed by the method of the present invention on the performance of an aqueous zinc ion battery is verified, and Comparative Example 1 and Comparative Example 2 are used as controls, as follows:

[0081] During the zinc deposition process, the coated DPE will hydrolyze, causing the pH at the zinc negative electrode interface to fluctuate, thereby inducing basic zinc sulfate to stack in parallel at the interface to form a dense protective layer. Figure 1Bare Zn, DPE@Zn and ZHS@Zn with the DPE layer peeled off after pre-cycling are shown respectively (after pre-cycling, a uniform ZHS layer (DPE / ZHS@Zn) will be formed in the middle of the DPE layer of Zn, and after the DPE layer is peeled off, it becomes ZHS@Zn). It can be seen that there are many scratches on the exposed zinc surface, which will lead to uneven surface electric field and ion distribution on the zinc surface, aggravating the growth of zinc dendrites. The surface of the DPE layer is smooth and flat, which effectively protects the zinc anode. After pre-cycling, a uniform ZHS layer can be observed on the zinc surface. Figure 2 X-ray diffractometer (XRD) can prove that the DPE layer is coated on the zinc surface and the ZHS is formed. Scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) can further observe the surface morphology and element distribution of ZHS, further proving the uniform formation of ZHS.

[0082] The generation of ZHS can significantly alleviate the side reactions between the zinc anode and water. Figure 3 In the linear sweep voltammogram (LSV) of the ZnO2 / Z ... Figure 4 The Tafel curve in Figure 2 shows the corrosion current of Bare Zn (icorr = 2.630 mA cm -2 ) and corrosion potential (Ecorr = -1.0081 V), while DPE / ZHS@Zn showed a lower corrosion current (icorr = 1.819 mA cm -2 ) and a higher corrosion potential (Ecorr = -1.0048 V), indicating that the double interface layer (the DPE layer induces the formation of a ZHS layer between the Zn and DPE interlayers, so the final double interface layer on the zinc surface is composed of two protective layers of DPE / ZHS) can effectively inhibit the corrosion of Zn and create conditions for the reversible and uniform deposition of zinc ions.

[0083] Figure 5 The chronoamperometry diagram and the final optical microscope diagram are shown in Figure 2. Figure 5 It can be seen from a that the current density at the bare zinc electrode continues to rise within 3600s, showing an extremely long 2D diffusion process, which will lead to the Zn 2+ tend to diffuse laterally along the surface and eventually deposit at the tip to form dendrites (e.g. Figure 5 This is in stark contrast to DPE / ZHS@Zn, where a long-term 3D diffusion process with stable and low current density occurs after the restricted 2D diffusion, which can promote the uniform and flat deposition of Zn and inhibit the growth of Zn dendrites (as shown in Fig. Figure 5This is in stark contrast to the situation where the bare Zn electrode diffuses laterally on the surface and easily deposits at the tip to form dendrites.

[0084] The electrochemical test results show that at 5 mA cm -2 The current density and 5 mAh cm -2 With the deposition capacity of 10 ... Figure 6 ).

[0085] The DPE@Zn and DPE@Cu in Example 1 (the preparation method of DPE@Cu is the same as that of DPE@Zn, the only difference is that the zinc sheet is replaced by a copper sheet) are assembled into a DPE@Zn||DPE@Cu half-cell, and the assembly method of the DPE@Zn||DPE@Cu half-cell is the same as that of the DPE@Zn / / DPE@Zn symmetric cell (only the electrodes are different); the Bare Zn in Comparative Example 1 is assembled into a Bare Zn||BareCu half-cell, and the specific method is as follows: the treatment method of Bare Cu is the same as that of Bare Zn, and the assembly method of the Bare Zn||Bare Cu half-cell is the same as that of the Zn / / Zn symmetric cell (only the electrodes are different), and the cycle performance is tested. At 5mA·cm -2 The current density and 5 mAh cm -2 With the deposition capacity of 1.37 W, the Coulombic efficiency of the DPE / ZHS@Zn||DPE / ZHS@Cu half-cell reached 99.89% after 300 cycles, while the Bare Zn||Bare Cu half-cell could only maintain 30 cycles before being destroyed by the growth of dendrites ( Figure 7 ).

[0086] In addition, after testing, the battery performance of Examples 2 to 7 has no significant difference from that of Example 1.

[0087] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for stabilizing the zinc negative electrode of an aqueous zinc ion battery, characterized in that: Dipentaerythritol is coated on the surface of a zinc sheet to form a coating layer, the thickness of the coating layer is 10 to 30 μm, and the zinc sheet coated with dipentaerythritol is used as the negative electrode of an aqueous zinc ion battery.

2. The method for stabilizing the zinc negative electrode of an aqueous zinc ion battery according to claim 1, wherein The following steps are involved: Firstly, dipentaerythritol and polyvinylidene fluoride are mixed, and then N-methylpyrrolidone is added, and the mixture is mixed evenly to obtain a slurry; The slurry is coated on the surface of the zinc sheet, and after drying, a water-based electrode coated with a coating is obtained; The aqueous zinc ion battery is assembled by using the aqueous electrode coated with the coating as a negative electrode.

3. The method for stabilizing the zinc negative electrode of an aqueous zinc ion battery according to claim 2, wherein The mass ratio of dipentaerythritol to polyvinylidene fluoride is (7-9):(1-3).

4. The method for stabilizing the zinc negative electrode of an aqueous zinc ion battery according to claim 3, wherein The mass ratio of the dipentaerythritol to polyvinylidene fluoride is 9:

1.

5. The method for stabilizing the zinc negative electrode of an aqueous zinc ion battery according to claim 2, wherein: Before coating the slurry on the surface of the zinc sheet, the zinc sheet is pretreated: one side of the zinc sheet is polished smooth with sandpaper, and then rinsed with water and anhydrous ethanol in sequence, and dried.

6. The method for stabilizing the zinc negative electrode of an aqueous zinc ion battery according to claim 1, wherein The aqueous zinc ion battery is a symmetrical battery or an asymmetrical battery.

7. The method for stabilizing the zinc negative electrode of an aqueous zinc ion battery according to claim 1, wherein The coating thickness is 20 μm.

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