Ultrathin dickite nanosheet enhanced aqueous zinc ion battery negative electrode protective coating and preparation method thereof

Abstract

The invention mainly aims to provide a preparation method of a cheap ultrathin dickite nanosheet and application of the ultrathin dickite nanosheet in a water-based zinc ion battery negative electrode protective coating aiming at the problems. The dickite which is low in price and has rich zinc-loving sites is used as an active substance in the coating, the zinc-loving performance of the coating is improved through a stripping method, and finally, a zinc sheet is coated with an ultrathin dickite nanosheet through a blade coating method, so that the zinc negative electrode is well protected, and the service life of the zinc negative electrode is prolonged. The corrosion effect of the weak acid electrolyte of the aqueous zinc ion battery on the negative electrode is weakened, the generation of byproducts and the growth of zinc dendrites are inhibited, the service life of the zinc negative electrode of the aqueous zinc ion battery is prolonged, and the electrochemical performance of the aqueous zinc ion battery is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of aqueous zinc ion batteries, and more specifically relates to a preparation method of ultra-thin geothermal nanosheets and application thereof in a negative electrode protective coating of aqueous zinc ion batteries. Background Art

[0002] With the large-scale use of clean energy such as wind and solar energy, it has become an urgent need to find a high-quality and low-cost energy storage system. Although lithium-ion batteries have mature production processes and use cases, their application in large-scale energy storage is limited to a certain extent due to their high cost and environmental hazards. In recent years, aqueous zinc-ion batteries have gradually become one of the most promising sustainable energy storage technologies due to their environmental friendliness and lower cost.

[0003] However, the zinc negative electrode in aqueous zinc-ion batteries is prone to problems such as dendrite growth, byproduct accumulation, and side reactions during long-term cycling, which brings the risk of battery failure. The existence of these problems also limits the large-scale use of zinc-ion batteries. Therefore, solving the above problems has become the key to the current research of zinc-ion batteries.

[0004] In recent years, studies have found that coating the surface of the zinc negative electrode of zinc ion batteries with artificial interface materials can effectively solve the above problems and significantly extend the life of the battery. However, artificial coatings made of relatively low-cost natural materials often have unstable performance due to uneven distribution. Therefore, modifying natural materials is of great significance for the commercial application of aqueous zinc ion batteries.

[0005] Two-dimensional materials are a new type of material with rich systems and unique topological structures. At the same time, because their carrier migration and heat diffusion are confined within the two-dimensional plane, this material exhibits many unique properties. These have led to the widespread application of two-dimensional materials in electrical devices, energy materials, and semiconductors. In recent years, research on two-dimensional materials represented by graphene has made a series of progress, but overall, research on the preparation of two-dimensional materials is still in its infancy and still faces many challenges. Therefore, it is still of great significance to find new methods for large-scale and low-cost preparation of two-dimensional materials.

[0006] A large number of two-dimensional materials in nature are two-dimensional monolayers stacked into three-dimensional structures through weak van der Waals forces. Among them, graphene, a typical representative of two-dimensional materials, is often stacked in graphite blocks in nature. In addition, there are many other materials with layered structures, such as layered silicate minerals, g-C3N4, 1T-MoS2 and MAX. Because these layered materials have excellent electrical and electrochemical properties, people have conducted a lot of research to obtain nanosheets of these layered materials. Among them, the liquid phase exfoliation method has excellent industrial prospects because of its simple process flow and relatively low requirements for production equipment. However, problems such as oxidation often occur in liquid phase exfoliation. Therefore, clay minerals, which are oxides with strong oxidation resistance, naturally become liquid phase exfoliation raw materials with broad prospects.

[0007] Ultra-thin two-dimensional materials such as graphene and MXene that are currently widely used are often conductors or semiconductors, which cannot be used in situations where clear insulation is required. Clay minerals themselves are insulating materials, and the emergence of exfoliated clay minerals has also filled the gap in the application of insulation. Although patent CN201510340731.5 proposes a delamination method with wide application value, the intercalant cannot be recycled. In addition, patents CN201711098630.7, CN201610963746.1, and CN201910468081.0 propose more environmentally friendly delamination methods, but they mainly focus on the delamination of graphite and g-C3N4 and other materials, and inevitably use high value-added items such as quantum dots in the delamination process, which is not conducive to large-scale production.

[0008] Unlike 2:1 clays such as montmorillonite, 1:1 clays such as dickite and kaolinite tend to curl when using liquid phase exfoliation. The use of mechanically assisted exfoliation methods can effectively alleviate the above problems (Colloid and Interface Science, 3482010355-359), but the exfoliation yield of kaolinite and dickite is often not high (Adv. Funct. Mater. 2019, 29, 1807611., Langmuir 2009, 25, 18, 10975-10979).

[0009] The electrospray ionization source works by using electrophoresis and heated air. When the droplets evaporate to a certain extent, the Coulomb repulsion on the droplet surface causes the droplets to explode, and the resulting small charged droplets continue this process. As the droplet molecules gradually evaporate, the clay can be exfoliated. At present, this electrophoresis method is mainly used in the field of chromatography analysis and has not been widely used in the field of sample preparation. Summary of the invention

[0010] The main purpose of the present invention is to provide a method for preparing an inexpensive ultra-thin dickite nanosheet and its application in a protective coating for the negative electrode of an aqueous zinc ion battery in view of the above problems. By using dickite, which is inexpensive and has abundant zinc affinity sites, as an active substance in the coating, and improving its zinc affinity by a stripping method, the ultra-thin dickite nanosheet is finally coated on the zinc sheet by a scraping method to achieve good protection of the zinc negative electrode, reduce the corrosion of the weak acid electrolyte of the aqueous zinc ion battery on the negative electrode, and inhibit the generation of by-products and the growth of zinc dendrites, thereby extending the service life of the zinc negative electrode of the aqueous zinc ion battery and improving the electrochemical performance of the aqueous zinc ion battery.

[0011] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0012] The present invention provides a method for preparing an ultra-thin dickite nanosheet-enhanced aqueous zinc ion battery negative electrode protective coating, comprising the following steps:

[0013] (1) adding dickite powder and a surfactant into dimethyl sulfoxide, stirring and mixing, and fully reacting to obtain intercalated dickite;

[0014] (2) dispersing the intercalated pyrophyllite in a sodium sulfate solution, and then adding the intercalated pyrophyllite into an ethanol solution of a silane coupling agent and stirring the solution;

[0015] (3) electrolyzing the fully stirred liquid under a DC power supply until no gas is generated, then treating the electrolyzed liquid with an electrospray ionization source, and condensing and refluxing the liquid;

[0016] (4) centrifuging the condensed liquid and freeze-drying the solid obtained by centrifugation to obtain ultra-thin geophilic nanosheet powder;

[0017] (5) mixing the prepared ultra-thin diatomite nanosheets with a binder and a solvent to obtain a slurry;

[0018] (6) coating the slurry on the surface of the zinc sheet with a coating thickness of 0.02 mm and freeze-drying. Preferably, the dickite needs to be purified to a purity of more than 95%, and the grinding diameter is less than 75 μm and screened with a 200 mesh sieve.

[0019] Further preferably, during the preparation of the intercalated dickite, every 1 g of dickite is treated with 20 mL of dimethyl sulfoxide.

[0020] Further preferably, the surfactant in the dickite intercalation process is one of non-ionic ethylene oxide condensate (HCS surfactant), non-ionic surfactant (SE surfactant), ethylene oxide condensate (SH surfactant), and alkyl glycoside natural surfactant (CG-110).

[0021] Further preferably, the amount of surfactant added during the dickite intercalation process is 10 μL of surfactant per 1 g of dickite.

[0022] Further preferably, the reaction temperature during the dickite intercalation process is 80° C. and the reaction time is 24 h.

[0023] Further preferably, the dimethyl sulfoxide used in the dickite intercalation process can be recycled.

[0024] Through this step, the dickite can be effectively intercalated with dimethyl sulfoxide. In this process, the addition of a surfactant can significantly improve the intercalation efficiency of the intercalation agent. Under conditions exceeding the concentration and temperature specified in the present invention, the intercalation effect of the dickite will be reduced, thereby making the subsequent stripping effect insignificant.

[0025] Further preferably, the silane coupling agent used in the kerite stripping process is one of bis-[γ-(triethoxysilyl)propyl]tetrasulfide (Si-69), vinyltriethoxysilane (A151), vinyltrimethoxysilane (A171), and γ-aminopropyltriethoxysilane (KH550).

[0026] Further preferably, during the dickite stripping process, the silane coupling agent is in an ethanol dispersion. Each 1 mL of the silane coupling agent is dissolved in 5000 mL of ethanol.

[0027] Further preferably, during the dickite stripping process, in the intercalated dickite dispersion, every 1 g of the intercalated dickite is dispersed in 500 mL of 0.5% sodium sulfate aqueous solution.

[0028] Further preferably, during the dickite stripping process, every 1 mL of sodium sulfate solution of the intercalated dickite is mixed with 10 mL of ethanol solution of the silane coupling agent.

[0029] Further preferably, during the dickite stripping process, the mixed solution must be mechanically stirred at 65° C. for 24 hours at a stirring speed of 480 rpm.

[0030] Further preferably, during the kerite stripping process, the mixed liquid must be electrolyzed under a 36V DC power supply until no gas is generated, and finally the electrolyzed liquid is treated using an electrospray ionization source and condensed and refluxed.

[0031] In this process, sodium sulfate is used to disperse the intercalated ground stone mainly to improve the conductivity of the liquid, thereby reducing the electrolysis time and improving production efficiency. Under the condition of exceeding the concentration of sodium sulfate of the present invention, too high a concentration will reduce the stripping effect, and too low a concentration will prolong the electrolysis time.

[0032] Further preferably, during the preparation of the electrode coating, the binder is one of aqueous polyurethane (APU), sodium carboxymethyl cellulose (CMC), sodium alginate (SA), and polyvinyl acetate adhesive (PVAc).

[0033] Further preferably, during the preparation of the electrode coating, the mass ratio of the exfoliated geophilic nanosheets to the binder is 1:1, and the solid-liquid mass ratio of the slurry is 1:20.

[0034] Further preferably, during the preparation of the electrode coating, the coating thickness is 0.02 mm and is freeze-dried.

[0035] The present invention also provides an electrode of a zinc ion battery comprising the composite coating as a negative electrode of an aqueous zinc ion battery.

[0036] Further preferably, the electrode of the zinc ion battery including the above-mentioned composite coating is used as the negative electrode of the aqueous zinc ion battery.

[0037] Compared with the prior art, the present invention also has the following advantages:

[0038] (1) Compared with other layered silicate minerals, the present invention peels off the blocky dickite to expose more zinc ion adsorption sites, which significantly improves the adsorption capacity of dickite for zinc ions.

[0039] (2) In all the preparation processes of the present invention, the solvents and chemicals used are environmentally friendly. At the same time, all the solvents in the preparation process can be recycled, which also significantly controls the preparation cost.

[0040] (3) The prepared ultrathin diopside nanosheets can exist stably at room temperature and pressure. At the same time, the ultrathin diopside nanosheets destroy the stacking of clay layers to the greatest extent while retaining the crystallinity.

[0041] (4) When the ultra-thin diatomite nanosheets proposed in the present invention are used as the negative electrode protective coating of aqueous zinc ion batteries, the negative charge on the surface of the diatomite can adsorb zinc ions in the electrolyte. At the same time, the polygonal structure formed by freeze-drying the binder can improve the transmission efficiency of zinc ions and inhibit the occurrence of side reactions.

[0042] (5) Compared with the negative electrode coating of the existing aqueous zinc-ion battery, the ultra-thin pyroxene nanosheet coating proposed in the present invention has the advantages of low cost and no need to use hazardous chemicals, which plays a significant role in promoting the commercial application of aqueous zinc-ion batteries.

[0043] (6) Compared with the negative electrode coating of the existing aqueous zinc ion battery, the ultra-thin pyroxene nanosheet coating proposed in the present invention has an excellent protective effect on the zinc substrate, can significantly inhibit the growth of dendrites and the generation of by-products, and at the same time reduce the corrosion of the electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 , scanning electron microscope image of the ultra-thin diatomite nanosheet prepared in Example 1;

[0045] Figure 2 , X-ray diffraction pattern of the ultra-thin geophyllite nanosheet prepared in Example 1;

[0046] Figure 3 , Atomic force microscope image of the ultra-thin geochite nanosheet prepared in Example 1;

[0047] Figure 4 , scanning electron microscope image of the coated negative electrode prepared in Example 1;

[0048] Figure 5 , the coated negative electrode prepared in Example 1 at 0.5 mA cm -2 The current density and 0.1 mAh cm -2 SEM image after 200h of cycling at a deposition capacity of ;

[0049] Figure 6 The negative electrode of Comparative Example 1 was -2 The current density and 0.1 mAh cm -2 SEM image after 200h of cycling at a deposition capacity of ;

[0050] Figure 7 The symmetrical battery assembled with the zinc electrodes prepared in Example 1 and Comparative Example 1 was -2 The current density and 0.1 mAh cm -2 Voltage-time diagram obtained at deposition capacity of . DETAILED DESCRIPTION

[0051] The technical content and effects of the present invention are further described in detail below in conjunction with the embodiments, but the present invention is not limited thereto.

[0052] Comparative Example 1 (pure zinc sheet electrode):

[0053] (1) A zinc sheet with a thickness of 0.05 mm was polished with sandpaper to remove the oxide layer on the surface.

[0054] (2) Cut the treated pure zinc sheet into electrode discs with a diameter of 12 mm.

[0055] Embodiment 1:

[0056] (1) Weigh 1 g of dickite and add it to 20 mL of dimethyl sulfoxide. Add 10 μL of HCS surfactant, stir at 180 rpm at 85 °C for 24 h, wash with ethanol and deionized water three times respectively, and dry in a vacuum at 70 °C for 10 h.

[0057] (2) Weigh 0.5 g of modified quartz and add it into 250 mL of sodium sulfate solution and stir at 180 rpm for 24 h.

[0058] (3) Pipette 0.5 mL of Si-69 into 2500 mL of anhydrous ethanol and stir at 180 rpm for 24 h.

[0059] (4) The modified distilled limestone dispersion was added to the Si-69 dispersion, stirred at 480 rpm for 24 h at 65 °C, and the mixed solution was electrolyzed using a 36 V DC power supply until no gas was generated. Finally, the electrolyzed liquid was treated with an electrospray ionization source, and the liquid was condensed and refluxed. The refluxed liquid was centrifuged and the solid was freeze-dried.

[0060] (5) Weigh 0.5 g of ultra-thin quartz nanosheets and 0.5 g of SA, add 20 mL of water, stir evenly, and then coat the mixture with a thickness of 0.02 mm on a zinc sheet with a thickness of 0.05 mm that has been sanded.

[0061] (6) After freeze-drying, the electrode was cut into electrode discs with a diameter of 12 mm.

[0062] Embodiment 2:

[0063] (1) Weigh 1 g of dickite and add it to 20 mL of dimethyl sulfoxide. Add 10 μL of HCS surfactant, stir at 180 rpm at 85 °C for 24 h, wash with ethanol and deionized water three times respectively, and dry in a vacuum at 70 °C for 10 h.

[0064] (2) Weigh 0.5 g of modified quartz and add it into 250 mL of sodium sulfate solution and stir at 180 rpm for 24 h.

[0065] (3) Pipette 0.5 mL of Si-69 into 2500 mL of anhydrous ethanol and stir at 180 rpm for 24 h.

[0066] (4) The modified distilled limestone dispersion was added to the Si-69 dispersion, stirred at 480 rpm for 24 h at 65 °C, and the mixed solution was electrolyzed using a 36 V DC power supply until no gas was generated. Finally, the electrolyzed liquid was treated with an electrospray ionization source, and the liquid was condensed and refluxed. The refluxed liquid was centrifuged and the solid was freeze-dried.

[0067] (5) Weigh 0.5 g of ultra-thin quartz nanosheets and 0.5 g of CMC, add 20 mL of water and stir evenly, then coat the mixture with a thickness of 0.02 mm on a zinc sheet with a thickness of 0.05 mm that has been sanded.

[0068] (6) After freeze-drying, the electrode was cut into electrode discs with a diameter of 12 mm.

[0069] Embodiment 3:

[0070] (1) Weigh 1 g of dickite and add it to 20 mL of dimethyl sulfoxide. Add 10 μL of HCS surfactant, stir at 180 rpm at 85 °C for 24 h, wash with ethanol and deionized water three times respectively, and dry in a vacuum at 70 °C for 10 h.

[0071] (2) Weigh 0.5 g of modified quartz and add it into 250 mL of sodium sulfate solution and stir at 180 rpm for 24 h.

[0072] (3) Pipette 0.5 mL of Si-69 into 2500 mL of anhydrous ethanol and stir at 180 rpm for 24 h.

[0073] (4) The modified distilled limestone dispersion was added to the Si-69 dispersion, stirred at 480 rpm for 24 h at 65 °C, and the mixed solution was electrolyzed using a 36 V DC power supply until no gas was generated. Finally, the electrolyzed liquid was treated with an electrospray ionization source, and the liquid was condensed and refluxed. The refluxed liquid was centrifuged and the solid was freeze-dried.

[0074] (5) Weigh 0.5 g of ultra-thin diatomite nanosheets and 0.5 g of APU, add 20 mL of water, stir evenly, and then coat the mixture with a thickness of 0.02 mm on a zinc sheet with a thickness of 0.05 mm that has been sanded.

[0075] (6) After freeze-drying, the electrode was cut into electrode discs with a diameter of 12 mm.

[0076] Embodiment 4:

[0077] (1) Weigh 1 g of dickite and add it to 20 mL of dimethyl sulfoxide. Add 10 μL of HCS surfactant, stir at 180 rpm at 85 °C for 24 h, wash with ethanol and deionized water three times respectively, and dry in a vacuum at 70 °C for 10 h.

[0078] (2) Weigh 0.5 g of modified quartz and add it into 250 mL of sodium sulfate solution and stir at 180 rpm for 24 h.

[0079] (3) Pipette 0.5 mL of Si-69 into 2500 mL of anhydrous ethanol and stir at 180 rpm for 24 h.

[0080] (4) The modified distilled limestone dispersion was added to the Si-69 dispersion, stirred at 480 rpm for 24 h at 65 °C, and the mixed solution was electrolyzed using a 36 V DC power supply until no gas was generated. Finally, the electrolyzed liquid was treated with an electrospray ionization source, and the liquid was condensed and refluxed. The refluxed liquid was centrifuged and the solid was freeze-dried.

[0081] (5) Weigh 0.5 g of ultra-thin diatomite nanosheets and 0.5 g of PVAc, add 20 mL of water, stir evenly, and then coat the mixture with a thickness of 0.02 mm on a zinc sheet with a thickness of 0.05 mm that has been sanded.

[0082] (6) After freeze-drying, the electrode was cut into electrode discs with a diameter of 12 mm.

[0083] Embodiment 5:

[0084] (1) Weigh 1 g of dickite and add it to 20 mL of dimethyl sulfoxide. Add 10 μL of HCS surfactant, stir at 180 rpm at 85 °C for 24 h, wash with ethanol and deionized water three times respectively, and dry in a vacuum at 70 °C for 10 h.

[0085] (2) Weigh 0.5 g of modified quartz and add it into 250 mL of sodium sulfate solution and stir at 180 rpm for 24 h.

[0086] (3) Add 0.5 mL of A151 into 2500 mL of anhydrous ethanol and stir at 180 rpm for 24 h.

[0087] (4) The modified distilled stone dispersion was added to the A151 dispersion, stirred at 480 rpm for 24 h at 65 °C, and the mixed solution was electrolyzed using a 36 V DC power supply until no gas was generated. Finally, the electrolyzed liquid was treated with an electrospray ionization source, and the liquid was condensed and refluxed. The refluxed liquid was centrifuged and the solid was freeze-dried.

[0088] (5) Weigh 0.5 g of ultra-thin quartz nanosheets and 0.5 g of SA, add 20 mL of water, stir evenly, and then coat the mixture with a thickness of 0.02 mm on a zinc sheet with a thickness of 0.05 mm that has been sanded.

[0089] (6) After freeze-drying, the electrode was cut into electrode discs with a diameter of 12 mm.

[0090] Embodiment 6:

[0091] (1) Weigh 1 g of dickite and add it to 20 mL of dimethyl sulfoxide. Add 10 μL of HCS surfactant, stir at 180 rpm at 85 °C for 24 h, wash with ethanol and deionized water three times respectively, and dry in a vacuum at 70 °C for 10 h.

[0092] (2) Weigh 0.5 g of modified quartz and add it into 250 mL of sodium sulfate solution and stir at 180 rpm for 24 h.

[0093] (3) Add 0.5 mL of A171 into 2500 mL of anhydrous ethanol and stir at 180 rpm for 24 h.

[0094] (4) The modified distilled stone dispersion was added to the A171 dispersion, stirred at 480 rpm for 24 h at 65 °C, and the mixed solution was electrolyzed using a 36 V DC power supply until no gas was generated. Finally, the electrolyzed liquid was treated with an electrospray ionization source, and the liquid was condensed and refluxed. The refluxed liquid was centrifuged and the solid was freeze-dried.

[0095] (5) Weigh 0.5 g of ultra-thin quartz nanosheets and 0.5 g of SA, add 20 mL of water, stir evenly, and then coat the mixture with a thickness of 0.02 mm on a zinc sheet with a thickness of 0.05 mm that has been sanded.

[0096] (6) After freeze-drying, the electrode was cut into electrode discs with a diameter of 12 mm.

[0097] Embodiment 7:

[0098] (1) Weigh 1 g of dickite and add it to 20 mL of dimethyl sulfoxide. Add 10 μL of HCS surfactant, stir at 180 rpm at 85 °C for 24 h, wash with ethanol and deionized water three times respectively, and dry in a vacuum at 70 °C for 10 h.

[0099] (2) Weigh 0.5 g of modified quartz and add it into 250 mL of sodium sulfate solution and stir at 180 rpm for 24 h.

[0100] (3) Pipette 0.5 mL of KH550 into 2500 mL of anhydrous ethanol and stir at 180 rpm for 24 h.

[0101] (4) The modified dikaite dispersion was added to the KH550 dispersion, stirred at 480 rpm for 24 h at 65 °C, and the mixed solution was electrolyzed using a 36 V DC power supply until no gas was generated. Finally, the electrolyzed liquid was treated with an electrospray ionization source, and the liquid was condensed and refluxed. The refluxed liquid was centrifuged and the solid was freeze-dried.

[0102] (5) Weigh 0.5 g of ultra-thin quartz nanosheets and 0.5 g of SA, add 20 mL of water, stir evenly, and then coat the mixture with a thickness of 0.02 mm on a zinc sheet with a thickness of 0.05 mm that has been sanded.

[0103] (6) After freeze-drying, the electrode was cut into electrode discs with a diameter of 12 mm.

[0104] Embodiment 8:

[0105] (1) Weigh 1 g of dickite and add it to 20 mL of dimethyl sulfoxide. Add 10 μL of SE surfactant, stir at 180 rpm at 85 °C for 24 h, wash with ethanol and deionized water three times respectively, and dry in a vacuum at 70 °C for 10 h.

[0106] (2) Weigh 0.5 g of modified quartz and add it into 250 mL of sodium sulfate solution and stir at 180 rpm for 24 h.

[0107] (3) Pipette 0.5 mL of Si-69 into 2500 mL of anhydrous ethanol and stir at 180 rpm for 24 h.

[0108] (4) The modified distilled limestone dispersion was added to the Si-69 dispersion, stirred at 480 rpm for 24 h at 65 °C, and the mixed solution was electrolyzed using a 36 V DC power supply until no gas was generated. Finally, the electrolyzed liquid was treated with an electrospray ionization source, and the liquid was condensed and refluxed. The refluxed liquid was centrifuged and the solid was freeze-dried.

[0109] (5) Weigh 0.5 g of ultra-thin diatomite nanosheets and 0.5 g of SA, add 20 mL of water, stir evenly, and then coat the mixture with a thickness of 0.02 mm on a zinc sheet with a thickness of 0.05 mm that has been sanded.

[0110] (6) After freeze-drying, the electrode was cut into electrode discs with a diameter of 12 mm.

[0111] Embodiment 9:

[0112] (1) Weigh 1 g of dickite and add it to 20 mL of dimethyl sulfoxide. Add 10 μL of SH surfactant, stir at 180 rpm at 85 °C for 24 h, wash with ethanol and deionized water three times respectively, and dry in a vacuum at 70 °C for 10 h.

[0113] (2) Weigh 0.5 g of modified quartz and add it into 250 mL of sodium sulfate solution and stir at 180 rpm for 24 h.

[0114] (3) Pipette 0.5 mL of Si-69 into 2500 mL of anhydrous ethanol and stir at 180 rpm for 24 h.

[0115] (4) The modified distilled limestone dispersion was added to the Si-69 dispersion, stirred at 480 rpm for 24 h at 65 °C, and the mixed solution was electrolyzed using a 36 V DC power supply until no gas was generated. Finally, the electrolyzed liquid was treated with an electrospray ionization source, and the liquid was condensed and refluxed. The refluxed liquid was centrifuged and the solid was freeze-dried.

[0116] (5) Weigh 0.5 g of ultra-thin diatomite nanosheets and 0.5 g of SA, add 20 mL of water, stir evenly, and then coat the mixture with a thickness of 0.02 mm on a zinc sheet with a thickness of 0.05 mm that has been sanded.

[0117] (6) After freeze-drying, the electrode was cut into electrode discs with a diameter of 12 mm.

[0118] Embodiment 10:

[0119] (1) Weigh 1 g of dickite and add it to 20 mL of dimethyl sulfoxide. Add 10 μL of CG-110, stir at 180 rpm at 85 °C for 24 h, wash with ethanol and deionized water three times respectively, and dry in a vacuum at 70 °C for 10 h.

[0120] (2) Weigh 0.5 g of modified quartz and add it into 250 mL of sodium sulfate solution and stir at 180 rpm for 24 h.

[0121] (3) Pipette 0.5 mL of Si-69 into 2500 mL of anhydrous ethanol and stir at 180 rpm for 24 h.

[0122] (4) The modified distilled limestone dispersion was added to the Si-69 dispersion, stirred at 480 rpm for 24 h at 65 °C, and the mixed solution was electrolyzed using a 36 V DC power supply until no gas was generated. Finally, the electrolyzed liquid was treated with an electrospray ionization source, and the liquid was condensed and refluxed. The refluxed liquid was centrifuged and the solid was freeze-dried.

[0123] (5) Weigh 0.5 g of ultra-thin diatomite nanosheets and 0.5 g of SA, add 20 mL of water, stir evenly, and then coat the mixture with a thickness of 0.02 mm on a zinc sheet with a thickness of 0.05 mm that has been sanded.

[0124] (6) After freeze-drying, the electrode was cut into electrode discs with a diameter of 12 mm.

[0125] Performance Testing

[0126] The electrode discs obtained in Examples 1-10 and Comparative Example 1 were used as positive and negative electrodes, glass fiber was used as a separator, and 2 mol / L zinc sulfate and 0.1 mol / L manganese sulfate solution were used as electrolytes to assemble symmetrical cells. The assembled symmetrical cells were charged at 0.5 mA cm -2 The current density and 0.1 mAh cm -2 Cyclic performance test at deposition capacity

[0127] Table 1

[0128]

[0129]

[0130] It can be seen from Table 1 that compared with the unprotected comparative example 1, the protected example 1 has an obvious protective effect, with a longer cycle life and a smaller polarization voltage.

[0131] By comparing the cycle life and polarization voltage of different electrodes in Examples 1-10, it can be seen that the surfactant added in the intercalation process, the silane coupling agent used in the stripping process, and the binder used in the electrode coating process have little effect on the cycle life and polarization voltage of the battery.

[0132] Depend on Figure 1 It can be seen that after peeling, the dickite showed an obvious flaky structure.

[0133] Depend on Figure 2 It can be seen that after delamination, the crystallinity of the dickite is significantly retained, while the diffraction peak representing the layer stacking basically disappears, which indicates that the delamination process achieves the delamination effect while ensuring the crystallinity of the dickite.

[0134] Depend on Figure 3 It can be seen that after peeling, the thickness of the dickite is about 3.7nm, which is calculated to be a 5-layer stack.

[0135] Depend on Figure 4 It can be seen that the coated zinc negative electrode exhibits an obvious polygonal structure.

[0136] like Figure 5 and 6 As shown, unlike the uncoated pure zinc electrode with obvious dendrites and by-products on the surface, the coated zinc electrode has a large number of dendrites and by-products on the surface after cycling, while the surface of the electrode in Example 1 protected by the coating still maintains its smoothness, indicating that the artificial coating effectively limits the growth of dendrites and the occurrence of side reactions.

[0137] Depend on Figure 7 It can be seen that the coated zinc negative electrode used in Example 1 can maintain voltage stability during a 5500-hour cycle, while the voltage of the pure zinc electrode in Comparative Example 1 changes significantly after 200 hours, indicating that the artificial coating with ultra-thin geophyllite nanosheets can effectively extend the service life of the electrode.

[0138] The above embodiments of the present invention are merely examples for illustrating the present invention, rather than limiting the specific implementation methods of the present invention. Other different forms of changes and modifications can be made based on the above description. It is impossible to list all implementation methods here.

Claims

1. A method for preparing an ultra-thin dickite nanosheet-enhanced aqueous zinc ion battery negative electrode protective coating, characterized in that: The steps include: (1) adding dickite powder and a surfactant into dimethyl sulfoxide, stirring and mixing, and fully reacting to obtain intercalated dickite; (2) dispersing the intercalated pyrophyllite in a sodium sulfate solution, and then adding the intercalated pyrophyllite into an ethanol solution of a silane coupling agent and stirring the solution; (3) electrolyzing the fully stirred liquid under a DC power supply until no gas is generated, then treating the electrolyzed liquid with an electrospray ionization source, and condensing and refluxing the liquid; (4) centrifuging the condensed liquid and freeze-drying the solid obtained by centrifugation to obtain ultra-thin geophilic nanosheet powder; (5) mixing the prepared ultra-thin diatomite nanosheets with a binder and a solvent to obtain a slurry; (6) The slurry is coated on the surface of the zinc sheet with a coating thickness of 0.02 mm and freeze-dried.

2. The method for preparing intercalated diatomite according to claim 1, characterized in that: The dickite needs to be purified to a purity of more than 95%, and at the same time, the grinding diameter is less than 75 μm, and screened with a 200-mesh sieve.

3. The ultra-thin geochite nanosheet according to claim 1, characterized in that: In the preparation process of the intercalated dickite described in step (1), every 1 g of dickite is treated with 20 mL of dimethyl sulfoxide.

4. The ultra-thin geochite nanosheet according to claim 1, characterized in that: The surfactant described in step (1) is any one of nonionic ethylene oxide condensate (HCS surfactant), nonionic surfactant (SE surfactant), ethylene oxide condensate (SH surfactant), and alkyl glycoside natural surfactant (CG-110).

5. The ultra-thin geochite nanosheet according to claim 1, characterized in that: The amount of surfactant added in step (1) is 10 μL of surfactant per 1 g of dickite.

6. The ultra-thin geochite nanosheet according to claim 1, characterized in that: In the intercalated pyrophyllite preparation process described in step (1), the dimethyl sulfoxide used can be reused; During the intercalation rock preparation process described in step (1), the reaction temperature is 80° C. and the reaction time is 24 hours.

7. The ultra-thin geochite nanosheet according to claim 1, characterized in that: The silane coupling agent described in step (2) is any one of bis-[γ-(triethoxysilyl)propyl]tetrasulfide (Si-69), vinyltriethoxysilane (A151), vinyltrimethoxysilane (A171), and γ-aminopropyltriethoxysilane (KH550).

8. The ultra-thin geochite nanosheet according to claim 1, characterized in that: The ethanol solution of the silane coupling agent described in step (2) is prepared by dissolving 1 mL of the silane coupling agent in 5000 mL of ethanol; The intercalated pyrophyllite described in step (2) is dispersed in a sodium sulfate solution, and each 1 g of the intercalated pyrophyllite is dispersed in 500 mL of a 0.5% sodium sulfate aqueous solution; The ethanol solution of the silane coupling agent described in step (2) is used in an amount of 10 mL of the ethanol solution of the silane coupling agent per 1 mL of the sodium sulfate solution of the intercalated pyrite; The ethanol solution of the silane coupling agent described in step (2) must be mechanically stirred at 65° C. for 24 h at a stirring speed of 480 rpm.

9. The ultra-thin geochrysolite nanosheet according to claim 1, characterized in that: The fully stirred liquid in step (3) must be electrolyzed under a 36V DC power supply until no gas is generated; The binder described in step (4) is any one of aqueous polyurethane (APU), sodium carboxymethyl cellulose (CMC), sodium alginate (SA), and polyvinyl acetate adhesive (PVAc); the solvent is water; the mass ratio of ultra-thin geolithium nanosheets to the binder is 1:1, and the solid-liquid mass ratio of the slurry is 1:

20.

10. An ultra-thin dickite nanosheet-enhanced aqueous zinc ion battery negative electrode protective coating, characterized in that: Prepared according to any one of claims 1-9.

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