A protective coating for the negative electrode of an ultrathin calcite nanosheet-reinforced aqueous zinc-ion battery and its preparation method

Abstract

The main objective of this invention is to address the aforementioned problems by providing a method for preparing inexpensive ultrathin dickite nanosheets and their application in the protective coating of the negative electrode of aqueous zinc-ion batteries. By using dickite, an inexpensive material with abundant zinc-affinity sites, as the active material in the coating, and enhancing its zinc-affinity properties through a peeling method, ultrathin dickite nanosheets are finally coated onto a zinc sheet using a scraping method. This achieves excellent protection for the zinc negative electrode, reduces the corrosive effect of the weakly acidic electrolyte of the aqueous zinc-ion battery on the negative electrode, inhibits the generation of byproducts and the growth of zinc dendrites, extends the service life of the zinc negative electrode in aqueous zinc-ion batteries, and improves the electrochemical performance of the aqueous zinc-ion battery.

Description

Technical Field

[0001] This invention belongs to the technical field of aqueous zinc-ion batteries, and more specifically relates to the preparation method of ultrathin dickite nanosheets and their application in the negative electrode protective coating of aqueous zinc-ion batteries. Background Technology

[0002] With the large-scale utilization of clean energy sources such as wind and solar power, finding a high-quality and inexpensive energy storage system has become an urgent need. Although lithium-ion batteries have mature production processes and application cases, their application in large-scale energy storage is limited to some 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, in aqueous zinc-ion batteries, the zinc anode is prone to dendrite growth, byproduct accumulation, and side reactions during long-term cycling, posing a risk of battery failure. These problems limit the large-scale application of zinc-ion batteries. Therefore, solving these problems has become a key research focus for zinc-ion batteries.

[0004] In recent years, research has found that coating the zinc anode surface of zinc-ion batteries with artificial interface materials can effectively solve the above-mentioned problems and significantly extend battery life. However, artificial coatings using relatively inexpensive natural materials often suffer from performance instability due to uneven distribution. Therefore, modifying natural materials is of great significance for the commercial application of aqueous zinc-ion batteries.

[0005] Two-dimensional (2D) materials are a novel class of materials. These materials possess a rich variety of systems and unique topologies. Furthermore, because carrier migration and heat diffusion are confined within a two-dimensional plane, these materials exhibit many unique properties. These properties have led to their widespread application in electrical devices, energy materials, and semiconductors. In recent years, research on 2D materials, represented by graphene, has made some progress. However, overall, research on the preparation of 2D materials is still in its early stages and faces many challenges. Therefore, finding new methods for the large-scale, low-cost preparation of 2D materials remains of great significance.

[0006] Many two-dimensional materials in nature exhibit three-dimensional structures formed by the stacking of two-dimensional monolayers through weak van der Waals forces. Graphene, a typical example of a two-dimensional material, often exists in nature as a mass of stacked graphite. Besides graphene, many other materials possess layered structures, such as layered silicate minerals, g-C3N4, 1T-MoS2, and MAX. These layered materials possess excellent electrical and electrochemical properties, leading to extensive research into obtaining nanosheets of them. Liquid-phase exfoliation, due to its simple process and low equipment requirements, shows great promise for industrialization. However, oxidation and other problems often arise during liquid-phase exfoliation. Therefore, clay minerals, which are themselves oxides and possess strong oxidation resistance, naturally become promising raw materials for liquid-phase exfoliation.

[0007] Currently, widely used ultrathin two-dimensional materials such as graphene and MXene are often conductors or semiconductors, which cannot be used in applications requiring explicit insulation. Clay minerals, on the other hand, are insulating materials, and the emergence of exfoliated clay minerals fills a gap in the field of insulation applications. Although patent CN201510340731.5 proposes an exfoliation method with broad application value, the intercalating agent cannot be recycled. In addition, patents CN201711098630.7, CN201610963746.1, and CN201910468081.0 propose more environmentally friendly exfoliation methods, but they mainly focus on the exfoliation of materials such as graphite and g-C3N4, and inevitably use high-value-added materials such as quantum dots in the exfoliation 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 liquid-phase exfoliation is used. Mechanically assisted exfoliation methods can effectively alleviate this problem (Colloid and Interface Science, 3482010355-359), but the exfoliation yield for kaolinite and dickite is often low (Adv. Funct. Mater. 2019, 29, 1807611., Langmuir 2009, 25, 18, 10975–10979).

[0009] Electrospray ionization sources operate by using electrophoresis and heated air. When a droplet evaporates to a certain extent, the Coulomb repulsion on the droplet surface causes it to explode. The resulting small charged droplets continue this process, and as the droplet molecules gradually evaporate, the clay can be delaminated. Currently, this electrophoresis method is mainly used in chromatographic analysis and has not yet achieved large-scale application in sample preparation. Summary of the Invention:

[0010] The main objective of this invention is to address the aforementioned problems by providing a method for preparing inexpensive ultrathin dickite nanosheets and their application in the protective coating of the negative electrode of aqueous zinc-ion batteries. By using dickite, an inexpensive material with abundant zinc-affinity sites, as the active material in the coating, and enhancing its zinc-affinity properties through a peeling method, ultrathin dickite nanosheets are finally coated onto a zinc sheet using a scraping method. This achieves excellent protection for the zinc negative electrode, reduces the corrosive effect of the weakly acidic electrolyte of the aqueous zinc-ion battery on the negative electrode, inhibits the generation of byproducts and the growth of zinc dendrites, extends the service life of the zinc negative electrode in aqueous zinc-ion batteries, and improves the electrochemical performance of the aqueous zinc-ion battery.

[0011] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0012] This invention provides a method for preparing an ultrathin dickite nanosheet-reinforced anode protective coating for aqueous zinc-ion batteries, comprising the following steps:

[0013] (1) Add dickite powder and surfactant to dimethyl sulfoxide, stir and mix, and react fully to obtain intercalated dickite;

[0014] (2) Disperse the intercalated kaolinite in a sodium sulfate solution, and then add it to an ethanol solution of silane coupling agent and stir.

[0015] (3) Electrolyze the thoroughly stirred liquid under a DC power supply until no gas is produced, then treat the electrolyzed liquid with an electrospray ionization source and condense and reflux the liquid;

[0016] (4) Centrifuge the condensed liquid and freeze-dry the solid obtained by centrifugation to obtain ultrathin dickite nanosheet powder;

[0017] (5) The prepared ultrathin kaolin nanosheets are mixed with binder and solvent to obtain a slurry;

[0018] (6) The slurry is coated onto the surface of the zinc sheet with a coating thickness of 0.02 mm and then freeze-dried. More preferably, the dickite needs to be purified to a purity of over 95%, with a grinding diameter of less than 75 μm, and screened using a 200-mesh sieve.

[0019] In a further preferred embodiment, during the preparation of intercalated dickite, each 1g of dickite is treated with 20mL of dimethyl sulfoxide.

[0020] More preferably, the surfactant used in the dickite intercalation process is one of the following: nonionic ethylene oxide condensate (HCS surfactant), nonionic surfactant (SE surfactant), ethylene oxide condensate (SH surfactant), or alkyl glycoside natural surfactant (CG-110).

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

[0022] Further preferred, the reaction temperature during the dickite intercalation process is 80℃, and the reaction time is 24h.

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

[0024] This step effectively intercalates dickite using dimethyl sulfoxide. The addition of a surfactant significantly improves the intercalation efficiency of the intercalating agent. However, exceeding the concentration and temperature limits specified in this invention will reduce the intercalation effect of dickite, resulting in ineffective subsequent delamination.

[0025] More preferably, the silane coupling agent used in the diatomite 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 delamination process of dickite, the silane coupling agent is in an ethanol dispersion. Each 1 mL of silane coupling agent is dissolved in 5000 mL of ethanol.

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

[0028] In a further preferred embodiment, during the delamination process of dickite, each 1 mL of sodium sulfate solution of intercalated dickite is mixed with 10 mL of ethanol solution of silane coupling agent.

[0029] In a further preferred embodiment, during the diatomite stripping process, the mixture must be mechanically stirred at 65°C for 24 hours at a stirring speed of 480 rpm.

[0030] In a further preferred embodiment, during the diatomite stripping process, the mixture must be electrolyzed under a 36V DC power supply until no gas is generated. Finally, the electrolyzed liquid is treated using an electrospray ionization source and then condensed and refluxed.

[0031] The use of sodium sulfate to disperse the intercalated shale in this process primarily increases the electrical conductivity of the liquid, thereby reducing electrolysis time and improving production efficiency. However, exceeding the sodium sulfate concentration specified in this invention will result in either a reduced exfoliation effect if the concentration is too high or a prolonged electrolysis time if the concentration is too low.

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

[0033] In a further preferred embodiment, during the electrode coating preparation process, the mass ratio of exfoliated calcite nanosheets to binder is 1:1, and the solid-liquid mass ratio of the slurry is 1:20.

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

[0035] The present invention also provides an electrode of a zinc-ion battery including the above-mentioned composite coating as the 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, exposing more zinc ion adsorption sites, which significantly improves the adsorption capacity of dickite for zinc ions.

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

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

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

[0042] (5) Compared with the existing negative electrode coating of aqueous zinc-ion batteries, the ultrathin calcite nanosheet coating proposed in this 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 existing negative electrode coating of aqueous zinc-ion batteries, the ultrathin calcite nanosheet coating proposed in this invention has excellent protective effect on the zinc substrate, can significantly inhibit dendrite growth and the generation of by-products, and at the same time reduce the corrosion of the electrode. Attached image description:

[0044] Figure 1 Scanning electron microscope image of the ultrathin dickite nanosheets prepared in Example 1;

[0045] Figure 2 X-ray diffraction pattern of the ultrathin dickite nanosheets prepared in Example 1;

[0046] Figure 3 Atomic force microscopy image of the ultrathin dickite nanosheets 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 was used at 0.5 mA cm⁻¹ -2 The current density and 0.1 mAh cm⁻¹ -2 Scanning electron microscope image after 200 h of cycling at the deposition capacity;

[0049] Figure 6 The negative electrode of Comparative Example 1 is at 0.5 mA cm -2 The current density and 0.1 mAh cm⁻¹ -2 Scanning electron microscope image after 200 h of cycling at the deposition capacity;

[0050] Figure 7 Symmetrical cells assembled using zinc electrodes prepared in Example 1 and Comparative Example 1 were tested at 0.5 mA cm⁻¹. -2 The current density and 0.1 mAh cm⁻¹ -2 Voltage-time plot obtained at the deposition capacity. Detailed implementation method:

[0051] The present invention will be further described in detail below with reference to the embodiments, and the technical content and effects thereof are not limited thereto.

[0052] Comparative Example 1 (Pure Zinc Sheet Electrode):

[0053] (1) The zinc sheet with a thickness of 0.05 mm is sanded 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] Example 1:

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

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

[0058] (3) Take 0.5 mL of Si-69 and add it to 2500 mL of anhydrous ethanol, and stir at 180 rpm for 24 h.

[0059] (4) Add the modified calcite dispersion to the Si-69 dispersion, stir at 480 rpm for 24 h at 65 °C, electrolyze the mixture with a 36 V DC power supply until no gas is generated, and finally treat the electrolyzed liquid with an electrospray ionization source, condense and reflux the liquid, centrifuge the refluxed liquid, and then freeze-dry the solid.

[0060] (5) Weigh 0.5g of ultrathin calcite nanosheets and 0.5g of SA, add 20mL of water and stir evenly, then coat the zinc sheet with a thickness of 0.02mm onto the zinc sheet with a thickness of 0.05mm after sanding.

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

[0062] Example 2:

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

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

[0065] (3) Take 0.5 mL of Si-69 and add it to 2500 mL of anhydrous ethanol, and stir at 180 rpm for 24 h.

[0066] (4) Add the modified calcite dispersion to the Si-69 dispersion, stir at 480 rpm for 24 h at 65 °C, electrolyze the mixture with a 36 V DC power supply until no gas is generated, and finally treat the electrolyzed liquid with an electrospray ionization source, condense and reflux the liquid, centrifuge the refluxed liquid, and then freeze-dry the solid.

[0067] (5) Weigh 0.5g of ultrathin calcite nanosheets and 0.5g of CMC, add 20mL of water and stir evenly, then coat the zinc sheet with a thickness of 0.02mm onto the zinc sheet with a thickness of 0.05mm after sanding.

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

[0069] Example 3:

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

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

[0072] (3) Take 0.5 mL of Si-69 and add it to 2500 mL of anhydrous ethanol, and stir at 180 rpm for 24 h.

[0073] (4) Add the modified calcite dispersion to the Si-69 dispersion, stir at 480 rpm for 24 h at 65 °C, electrolyze the mixture with a 36 V DC power supply until no gas is generated, and finally treat the electrolyzed liquid with an electrospray ionization source, condense and reflux the liquid, centrifuge the refluxed liquid, and then freeze-dry the solid.

[0074] (5) Weigh 0.5g of ultrathin calcite nanosheets and 0.5g of APU, add 20mL of water and stir evenly, then coat the zinc sheet with a thickness of 0.02mm onto the zinc sheet with a thickness of 0.05mm after sanding.

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

[0076] Example 4:

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

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

[0079] (3) Take 0.5 mL of Si-69 and add it to 2500 mL of anhydrous ethanol, and stir at 180 rpm for 24 h.

[0080] (4) Add the modified calcite dispersion to the Si-69 dispersion, stir at 480 rpm for 24 h at 65 °C, electrolyze the mixture with a 36 V DC power supply until no gas is generated, and finally treat the electrolyzed liquid with an electrospray ionization source, condense and reflux the liquid, centrifuge the refluxed liquid, and then freeze-dry the solid.

[0081] (5) Weigh 0.5g of ultrathin calcite nanosheets and 0.5g of PVAc, add 20mL of water and stir evenly, then coat the zinc sheet with a thickness of 0.02mm onto the zinc sheet with a thickness of 0.05mm after sanding.

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

[0083] Example 5:

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

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

[0086] (3) Take 0.5 mL of LA151 and add it to 2500 mL of anhydrous ethanol, and stir at 180 rpm for 24 h.

[0087] (4) Add the modified calcite dispersion to the A151 dispersion, stir at 480 rpm for 24 h at 65 °C, electrolyze the mixture with a 36 V DC power supply until no gas is generated, and finally treat the electrolyzed liquid with an electrospray ionization source, condense and reflux the liquid, centrifuge the refluxed liquid, and then freeze-dry the solid.

[0088] (5) Weigh 0.5g of ultrathin calcite nanosheets and 0.5g of SA, add 20mL of water and stir evenly, then coat the zinc sheet with a thickness of 0.02mm onto the zinc sheet with a thickness of 0.05mm after sanding.

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

[0090] Example 6:

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

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

[0093] (3) Take 0.5 mL of LA171 and add it to 2500 mL of anhydrous ethanol, and stir at 180 rpm for 24 h.

[0094] (4) Add the modified calcite dispersion to the A171 dispersion, stir at 480 rpm for 24 h at 65 °C, electrolyze the mixture with a 36 V DC power supply until no gas is generated, and finally treat the electrolyzed liquid with an electrospray ionization source, condense and reflux the liquid, centrifuge the refluxed liquid, and then freeze-dry the solid.

[0095] (5) Weigh 0.5g of ultrathin calcite nanosheets and 0.5g of SA, add 20mL of water and stir evenly, then coat the zinc sheet with a thickness of 0.02mm onto the zinc sheet with a thickness of 0.05mm after sanding.

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

[0097] Example 7:

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

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

[0100] (3) Take 0.5 mL of KH550 and add it to 2500 mL of anhydrous ethanol, and stir at 180 rpm for 24 h.

[0101] (4) Add the modified calcite dispersion to the KH550 dispersion, stir at 480 rpm for 24 h at 65 °C, electrolyze the mixture with a 36 V DC power supply until no gas is generated, and finally treat the electrolyzed liquid with an electrospray ionization source, condense and reflux the liquid, centrifuge the refluxed liquid, and then freeze-dry the solid.

[0102] (5) Weigh 0.5g of ultrathin calcite nanosheets and 0.5g of SA, add 20mL of water and stir evenly, then coat the zinc sheet with a thickness of 0.02mm onto the zinc sheet with a thickness of 0.05mm after sanding.

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

[0104] Example 8:

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

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

[0107] (3) Take 0.5 mL of Si-69 and add it to 2500 mL of anhydrous ethanol, and stir at 180 rpm for 24 h.

[0108] (4) Add the modified calcite dispersion to the Si-69 dispersion, stir at 480 rpm for 24 h at 65 °C, electrolyze the mixture with a 36 V DC power supply until no gas is generated, and finally treat the electrolyzed liquid with an electrospray ionization source, condense and reflux the liquid, centrifuge the refluxed liquid, and then freeze-dry the solid.

[0109] (5) Weigh 0.5g of ultrathin calcite nanosheets and 0.5g of SA, add 20mL of water and stir evenly, then coat the zinc sheet with a thickness of 0.02mm onto the zinc sheet with a thickness of 0.05mm after sanding.

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

[0111] Example 9:

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

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

[0114] (3) Take 0.5 mL of Si-69 and add it to 2500 mL of anhydrous ethanol, and stir at 180 rpm for 24 h.

[0115] (4) Add the modified calcite dispersion to the Si-69 dispersion, stir at 480 rpm for 24 h at 65 °C, electrolyze the mixture with a 36 V DC power supply until no gas is generated, and finally treat the electrolyzed liquid with an electrospray ionization source, condense and reflux the liquid, centrifuge the refluxed liquid, and then freeze-dry the solid.

[0116] (5) Weigh 0.5g of ultrathin calcite nanosheets and 0.5g of SA, add 20mL of water and stir evenly, then coat the zinc sheet with a thickness of 0.02mm onto the zinc sheet with a thickness of 0.05mm after sanding.

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

[0118] Example 10:

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

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

[0121] (3) Take 0.5 mL of Si-69 and add it to 2500 mL of anhydrous ethanol, and stir at 180 rpm for 24 h.

[0122] (4) Add the modified calcite dispersion to the Si-69 dispersion, stir at 480 rpm for 24 h at 65 °C, electrolyze the mixture with a 36 V DC power supply until no gas is generated, and finally treat the electrolyzed liquid with an electrospray ionization source, condense and reflux the liquid, centrifuge the refluxed liquid, and then freeze-dry the solid.

[0123] (5) Weigh 0.5g of ultrathin calcite nanosheets and 0.5g of SA, add 20mL of water and stir evenly, then coat the zinc sheet with a thickness of 0.02mm onto the zinc sheet with a thickness of 0.05mm after sanding.

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

[0125] Performance testing

[0126] Using the electrode discs obtained in Examples 1-10 and Comparative Example 1 as positive and negative electrodes, with glass fiber as the separator, and a 2 mol / L zinc sulfate and 0.1 mol / L manganese sulfate solution as the electrolyte, a symmetrical cell was assembled. The assembled symmetrical cell was then subjected to an induction heating at 0.5 mA / cm² in a constant temperature environment of 25°C. -2 The current density and 0.1 mAh cm⁻¹ -2 Cyclic performance testing was conducted at the deposition capacity.

[0127] Table 1

[0128]

[0129]

[0130] As can be seen from Table 1, compared with the unprotected Comparative Example 1, the protected Example 1 has a significant protective effect, with a longer cycle life and a lower 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 during the intercalation process, the silane coupling agent used during the stripping process, and the binder used during 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 exfoliation, the dickite exhibits a distinct flaky structure.

[0133] Depend on Figure 2 It can be seen that after exfoliation, the crystallinity of dickite was significantly preserved, while the diffraction peaks representing layer stacking basically disappeared. This indicates that the exfoliation process achieved the exfoliation effect while ensuring the crystallinity of dickite.

[0134] Depend on Figure 3 It can be seen that after delamination, the thickness of the dickite is about 3.7 nm, which is calculated to be 5 layers stacked.

[0135] Depend on Figure 4 It can be seen that the coated zinc anode exhibits a distinct polygonal structure.

[0136] like Figure 5 and 6 As shown, unlike the uncoated pure zinc electrode surface which has obvious dendrites and byproducts, the coated zinc electrode has a large number of dendrites and byproducts on its surface after cycling, while the electrode surface of Example 1, which is protected by the coating, still maintains a smooth surface, 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 zinc anode with coating protection used in Example 1 can maintain stable voltage during 5500h cycling, while the pure zinc electrode in Comparative Example 1 showed a significant voltage change after 200h. This indicates that the artificial coating with ultrathin dickite nanosheets can effectively extend the service life of the electrode.

[0138] The above embodiments of the present invention are merely illustrative examples and not intended to limit the specific implementation of the invention. Other variations and modifications can be made based on the above description. It is impossible to exhaustively list all possible implementations here.

Claims

1. A method for preparing an ultrathin dickite nanosheet-reinforced anode protective coating for an aqueous zinc-ion battery, characterized in that, Includes the following steps: (1) Add dickite powder and surfactant to dimethyl sulfoxide, stir and mix, and react fully to obtain intercalated dickite; (2) Disperse the intercalated kaolinite in a sodium sulfate solution, and then add it to an ethanol solution of silane coupling agent and stir. (3) Electrolyze the thoroughly stirred liquid under a DC power supply until no gas is produced, then treat the electrolyzed liquid with an electrospray ionization source and condense and reflux the liquid; (4) Centrifuge the condensed liquid and freeze-dry the solid obtained by centrifugation to obtain ultrathin dickite nanosheet powder; (5) The prepared ultrathin kaolin nanosheets are mixed with binder and solvent to obtain a slurry; (6) Coat the zinc sheet with the slurry to a thickness of 0.02 mm and freeze dry.

2. The preparation method according to claim 1, characterized in that, The kaolinite needs to be purified to a purity of over 95%, with a grinding diameter of less than 75 micrometers, and screened using a 200-mesh sieve.

3. The preparation method according to claim 1, characterized in that, In the preparation process of intercalated dickite described in step (1), each 1g of dickite is treated with 20mL of dimethyl sulfoxide.

4. The preparation method according to claim 1, characterized in that, The surfactant mentioned in step (1) is any one of nonionic ethylene oxide condensate, nonionic surfactant, ethylene oxide condensate, or alkyl glycoside natural surfactant.

5. The preparation method according to claim 1, characterized in that, The amount of surfactant added in step (1) is 10 microliters of surfactant per 1g of dickite.

6. The preparation method according to claim 1, characterized in that, In the process of preparing intercalated calcite described in step (1), the dimethyl sulfoxide used can be reused: In step (1), during the preparation of the intercalated quartz, the reaction temperature is 80°C. o C, the reaction time is 24h.

7. The preparation method according to claim 1, characterized in that, The silane coupling agent mentioned in step (2) is any one of bis-[γ-(triethoxysilane)propyl]tetrasulfide, vinyltriethoxysilane, vinyltrimethoxysilane, and γ-aminopropyltriethoxysilane.

8. The preparation method according to claim 1, characterized in that, The ethanol solution of the silane coupling agent mentioned in step (2) is prepared by dissolving 1 mL of the silane coupling agent in 5000 mL of ethanol. The intercalated kaolinite described in step (2) is dispersed in a sodium sulfate solution, with each 1g of intercalated kaolinite dispersed in 500mL of 0.5% sodium sulfate aqueous solution; The ethanol solution of the silane coupling agent mentioned in step (2) is prepared by mixing 1 mL of sodium sulfate solution of intercalated dickite with 10 mL of ethanol solution of silane coupling agent. The ethanol solution of the silane coupling agent described in step (2) must be mechanically stirred at 65°C for 24 hours at a stirring speed of 480 rpm.

9. The preparation method according to claim 1, characterized in that, The thoroughly stirred liquid described in step (3) must be electrolyzed under a 36V DC power supply until no gas is generated: The adhesive used in step (5) is any one of waterborne polyurethane, sodium carboxymethyl cellulose, sodium alginate, or polyvinyl acetate adhesive; the solvent is water; the mass ratio of ultrathin calcite nanosheets to adhesive is 1:1, and the solid-liquid mass ratio of slurry is 1:

20.

10. A protective coating for the negative electrode of an ultrathin dickite nanosheet-reinforced aqueous zinc-ion battery, characterized in that, Prepared according to any one of claims 1-9.

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