Zinc negative electrode of aqueous zinc ion battery as well as preparation method and application of zinc negative electrode

Abstract

The invention relates to the technical field of aqueous zinc ion batteries, in particular to an aqueous zinc ion battery zinc negative electrode and a preparation method and application thereof, and the preparation method comprises the following steps: preparing coating slurry comprising InMOF nanoparticles, a solvent and an adhesive; heating the zinc negative pole piece to 140-160 DEG C; spraying the coating slurry to the surface of a zinc negative electrode plate, then drying, and pyrolyzing the coating slurry to obtain the zinc negative electrode with the MOF coating; the InMOF nano-particle coating is introduced into the zinc negative electrode, and a three-dimensional porous network structure formed by InMOF nano-particles can be used as a rigid zinc ion transmission channel, so that dendritic crystal growth is inhibited, the service life of the battery is prolonged, and the electrochemical performance is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aqueous zinc-ion batteries, in particular to an aqueous zinc-ion battery zinc anode and a preparation method and application thereof. BACKGROUND

[0002] Aqueous zinc-ion batteries (AZMBs) are strong candidates for the next generation of energy storage due to the low redox potential (-0.76 V vs SHE), high theoretical capacity (820 mAh g⁻¹ or 5855 mAh cm⁻³), abundant resources, and high safety of zinc anodes.

[0003] However, the zinc anode of aqueous zinc-ion batteries faces the problems of continuous dendrite growth and serious side reactions, which leads to poor reversibility and insufficient stability, directly restricting the cycle life and coulombic efficiency of the battery, and hindering the industrialization process of AZMBs.

[0004] The information disclosed in this BACKGROUND section is only for the purpose of enhancing the understanding of the general background of the application and should not be taken as an acknowledgement or any form of suggestion that this information forms prior art that is publicly known in the field. SUMMARY

[0005] The first object of the present application is to provide an aqueous zinc-ion battery zinc anode, which introduces an InMOF nanoparticle coating on the zinc anode. The three-dimensional porous network structure formed by the InMOF nanoparticles can serve as a rigid zinc ion transmission channel, inhibiting dendrite growth, prolonging the service life of the battery, and improving the electrochemical performance.

[0006] The above technical object of the present application is achieved by the following technical solution: A preparation method of an aqueous zinc-ion battery zinc anode, comprising: Preparation of a coating slurry comprising InMOF nanoparticles, a solvent and a binder; more specifically, mixing InMOF nanoparticles, a solvent and a binder, and obtaining a coating slurry after ultrasonic stirring for at least 24 h; More specifically, InMOF is an indium-based metal organic framework formed by self-assembly of indium ions and organic ligands through coordination bonds, which has a three-dimensional porous network structure, a large specific surface area and abundant active sites, the pore size and shape can be controlled according to the synthesis conditions, the structure contains hydrophobic channels or functional groups such as -ClO4, the crystal structure is stable, and the atoms are arranged in order; In this step, the InMOF nanoparticles and the binder are fully mixed by the solvent to form a uniformly dispersed fluid state. The InMOF nanoparticles, as the active material of the coating, can form a three-dimensional porous network structure to serve as zinc ion transport channels. The binder enables the InMOF nanoparticles to be stably bound, providing a basis for the subsequent formation of an effective coating on the zinc anode surface. Heat the zinc negative electrode sheet to 140~160℃; more specifically, the zinc negative electrode sheet is prepared by cutting a 50μm thick zinc foil into 5cm*5cm electrode sheets; in this step, preheating the electrode sheet can promote the rapid evaporation of solvent in the coating slurry during spraying, and at the same time provide a suitable temperature for the subsequent pyrolysis reaction of the coating, ensuring that the coating is quickly set on the electrode sheet surface and reducing coating defects caused by solvent residue; The coating slurry is sprayed onto the surface of the zinc anode sheet and then dried. The coating slurry is then pyrolyzed to obtain a zinc anode with an MOF coating. More specifically, the spraying method enables the slurry to form a uniform coverage on the electrode surface. The drying step further removes residual solvents, and the preheating temperature triggers the pyrolysis of the coating slurry, allowing the InMOF nanoparticles to be transformed into a stable MOF coating through the pyrolysis reaction, which is then firmly attached to the surface of the zinc anode. At the pyrolysis temperature, some of the weak bonds inside InMOF nanoparticles break, while the remaining indium ions and organic ligands rearrange and recombine through more stable coordination bonds to form a more compact MOF coating with stronger bonding. In the above process, the solvent evaporates completely at high temperature, and the binder undergoes molecular chain shrinkage and solidification due to the temperature rise. On the one hand, it firmly fixes the InMOF particles through physical bonding, preventing particle agglomeration or detachment during pyrolysis. On the other hand, its polar groups interact with the metal sites or ligand functional groups on the InMOF surface, synergistically strengthening the bonding force between particles and between particles and the zinc anode surface. Through pyrolysis, the transformation from dispersed InMOF nanoparticles to a continuous, stable MOF coating that retains its porous properties is achieved.

[0007] More specifically, the zinc negative electrode sheet after spraying is placed in a vacuum drying oven for drying.

[0008] This invention introduces an InMOF nanoparticle coating at the zinc metal anode interface. The three-dimensional porous network structure formed by the InMOF particles serves as a rigid zinc ion transport channel. Its high mass-to-charge ratio decouples the ion flux from the inhomogeneity of the electrode substrate, reducing local electric field distortion and thus inhibiting preferential zinc ion deposition at the bumps. This flow equalization effect directly reduces dendrite nucleation sites. Furthermore, the hydrophobic channels or functionalized groups (such as -ClO4) of the InMOF nanoparticles can accelerate the deposition of [Zn(H2O)6]. 2+ The desolvation process reduces the chance of active water molecules contacting the zinc surface, which significantly reduces the hydrogen evolution reaction and the formation of byproducts, thereby improving coulombic efficiency.

[0009] As a preferred embodiment of the present invention, the solvent is N-methylpyrrolidone (NMP) with a concentration ≥99.9%; More specifically, N-methylpyrrolidone (NMP) as a solvent has good compatibility with InMOF nanoparticles and binders, forming a stable coating slurry and ensuring the uniformity of the coating during subsequent spraying. At the same time, NMP has suitable volatility and can evaporate rapidly when the zinc negative electrode sheet is heated to 140~160℃, ensuring that the coating quickly sets and adheres firmly to the zinc foil surface, reducing coating defects caused by solvent residue.

[0010] As a preferred embodiment of the present invention, the adhesive is polyvinylidene fluoride (PVDF). More specifically, polyvinylidene fluoride (PVDF) is selected as the binder. It has good solubility in N-methylpyrrolidone and can be uniformly mixed with InMOF nanoparticles to form a stable coating slurry. PVDF has excellent adhesion properties, which can firmly attach InMOF nanoparticles to the zinc foil surface, maintain the integrity of the coating structure during drying and battery cycling, and prevent particle detachment. In addition, PVDF has high chemical stability and does not easily react in aqueous electrolyte environments.

[0011] In a preferred embodiment of the present invention, the loading of InMOF nanoparticles on the zinc anode is 0.5~2 mg / cm³. 2 ; More specifically, the loading range mentioned above can ensure that the InMOF nanoparticles in the coating form a complete three-dimensional porous network structure, providing sufficient rigid transport channels for zinc ions, while avoiding excessive coating thickness due to excessive loading, which would hinder zinc ion transport efficiency or increase interfacial resistance.

[0012] As a preferred embodiment of the present invention, the ratio of InMOF nanoparticles, solvent and binder is 25~90mg:2.5~10mg:2~3mL; More specifically, the above dosage ratio ensures that the InMOF nanoparticles are uniformly dispersed in the solvent under the action of the binder, forming a stable and sprayable slurry, thus guaranteeing the uniformity of the coating. It also avoids the decrease in the conductivity of the coating due to excessive binder or the impact of excessive solvent on drying efficiency.

[0013] A second objective of this invention is to provide a zinc anode prepared by the above-described method for preparing a zinc anode for an aqueous zinc-ion battery.

[0014] A third objective of this invention is to provide an application of the zinc anode prepared using the above-described method for preparing an aqueous zinc-ion battery anode, which is used in an aqueous zinc-ion battery. The method for preparing an aqueous zinc-ion battery includes: (1) Mix the positive electrode material, conductive carbon black and binder evenly to obtain a slurry, then coat the slurry evenly on the current collector and dry it to obtain a positive electrode sheet; (2) Assemble the negative electrode shell, the above-mentioned zinc negative electrode, the separator, the electrolyte, the positive electrode plate, the gasket, the spring and the positive electrode shell to obtain an aqueous zinc-ion battery.

[0015] As a preferred embodiment of the present invention, in step (1), the mass ratio of positive electrode material, conductive carbon black and binder is 70~80%:10~20%:10%; more specifically, the above mass ratio can ensure a high proportion of positive electrode material to provide sufficient electrochemical active sites and ensure high battery capacity, and can also improve the conductivity of positive electrode through an appropriate amount of conductive carbon black, promote electron transport and reduce polarization. At the same time, 10% binder can firmly bond the positive electrode material and conductive carbon black to the current collector, maintain the structural stability of the positive electrode sheet and prevent the active material from falling off during cycling. The positive electrode material is at least one of vanadium pentoxide and ammonium vanadate; more specifically, the two materials mentioned above have good electrochemical activity and zinc ion storage capacity, and can form a highly efficient matching electrode system with the zinc negative electrode with InMOF coating.

[0016] As a preferred embodiment of the present invention, the electrolyte solute is at least one of ZnOTF and ZnSO4.

[0017] As a preferred embodiment of the present invention, the coating thickness of the slurry is 100~150μm; More specifically, the thickness of the slurry ensures that the cathode material has sufficient mass loading to provide a high battery capacity, while avoiding problems such as excessively long ion transport paths and blocked electron conduction caused by excessive thickness, thus reducing polarization.

[0018] As a preferred embodiment of the present invention, the adhesive is polyvinylidene fluoride; More specifically, PVDF has excellent bonding properties, which can firmly bond the positive electrode material and conductive carbon black to the current collector, maintain the structural integrity of the positive electrode sheet during drying and battery cycling, prevent the active material from falling off, and has high chemical stability. It is not easy to react in an aqueous electrolyte environment and will not interfere with the electrochemical performance of the positive electrode.

[0019] As a preferred embodiment of the present invention, the drying temperature in step (1) is 50~100℃ and the time is 8~24h.

[0020] As a preferred embodiment of the present invention, in step (2), the diaphragm is made of glass fiber.

[0021] Compared with the prior art, the beneficial effects of this invention are as follows: The InMOF nanoparticle coating introduced in this invention at the zinc metal anode interface can form a three-dimensional porous network structure that serves as a rigid zinc ion transport channel. Its high mass-to-charge ratio decouples the ion flux from the inhomogeneity of the electrode substrate, weakens local electric field distortion, and thus inhibits the preferential deposition of zinc ions at the bumps. This flow equalization effect directly reduces dendrite nucleation sites. The hydrophobic channels or functionalized groups of the InMOF nanoparticles can accelerate the deposition of [Zn(H2O)6]. 2+ The desolvation process reduces the chance of active water molecules contacting the zinc surface, which significantly reduces the hydrogen evolution reaction and the formation of byproducts, thereby improving coulombic efficiency. The aqueous zinc-ion battery of the present invention includes the above-mentioned zinc negative electrode, which can suppress dendrite growth, greatly extend the battery's service life, and improve electrochemical performance. The coating preparation method of the present invention has the advantages of being simple, environmentally friendly, easy to operate and low in cost, and has the potential for large-scale application. Attached Figure Description

[0022] Figure 1 This is a comparison chart of the cycle life of zinc-zinc symmetric batteries in Example 1 and Comparative Example 1 of the present invention; Figure 2 This is a SEM image of the zinc anode surface after coating with InMOF nanoparticles in Example 1 of the present invention. Figure 3 The above are SEM images of the zinc negative electrode after cycling of the zinc-zinc symmetric batteries assembled in Example 1 and Comparative Example 1 of this invention. Figure 4 The coulombic efficiency diagrams are shown for the zinc-copper asymmetric cells assembled in Example 2 and Comparative Example 2 of this invention. Figure 5 The cycling performance diagrams are for the aqueous zinc-ion full cells assembled in Example 3 and Comparative Example 3 of this invention. Figure 1 , Figures 3-5 In this context, BARE refers to an electrode without a coating, while Zn@InMOF refers to an electrode with an InMOF nanoparticle coating according to the present invention. Detailed Implementation

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0024] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0025] Unless otherwise specified, the methods described in the specific implementation are conventional methods, and the raw materials or instruments can be obtained commercially unless otherwise specified.

[0026] The electrolyte used in the examples and comparative examples consisted of 1.61 g of ZnSO4 and 5 mL of deionized water. The preparation method is as follows: dissolve ZnSO4 in deionized water and stir to mix evenly.

[0027] Example 1: The aqueous zinc-ion battery of this embodiment is prepared through the following steps: S1 cuts 50μm thick zinc foil into 5cm*5cm electrode sheets, lays them flat on the heating table, and heats them at 150℃. S2 dissolves 90mg InMOF nanoparticles and 10mg PVDF in 3mL NMP, stirs at 150-250rpm and sonicates for 24h, injects the resulting coating slurry into a spray gun, sprays it onto the 5cm*5cm zinc metal electrode sheet, and then places it in a vacuum drying oven at 100℃ for 12h. S3 cuts the sprayed zinc foil into electrode sheets with a diameter of 12 mm, and presses them under a pressure of 5 MPa to obtain zinc metal electrode sheets with an InMOF coating. The loading of InMOF nanoparticles was measured to be 0.5 mg / cm³. 2 ; S4 is assembled into a zinc-zinc symmetrical battery consisting of a positive electrode shell, coated zinc foil (positive electrode), separator, electrolyte, coated zinc foil, gasket, spring, and negative electrode shell.

[0028] Comparative Example 1: The difference from Example 1 is that the preparation method of the zinc anode was changed, and the InMOF nanoparticle coating was not added. The specific method is as follows: Zinc foil with a thickness of 50 μm was cut into electrode sheets with a diameter of 12 mm, pressed under a pressure of 5 MPa, and then placed in an ethanol solution, sonicated for 5 min, and naturally dried in air to obtain zinc electrode sheets. The rest is the same as in Example 1.

[0029] The test schemes and analysis results of Example 1 and Comparative Example 1 are as follows: The zinc-zinc symmetric cells assembled in Example 1 and Comparative Example 1, at 2 mA cm -2 1mAh cm -2 Cycling is performed at current density. Figure 1 This illustrates a symmetrical cell at 2mA cm -2 1mAh cm -2The cycle performance diagram of discharge at current density shows that the stable cycle time of Example 1 exceeds 800h, while the stable cycle time of Comparative Example 1 only reaches 150 cycles, with a maximum improvement of 500%. This indicates that the zinc metal anode with InMOF nanoparticle coating has more controllable polarization and stable material structure.

[0030] Figure 2 The image shows a SEM image of the zinc anode surface after InMOF nanoparticles were sprayed on. The scale bar on the left is 100 μm and the scale bar on the right is 2 μm. It can be seen from the image that the InMOF nanoparticle coating is uniformly attached to the zinc anode surface. Figure 3 SEM images of the zinc anode surface with InMOF nanoparticle coating after cycling are shown at 2 mA cm⁻¹. -2 1mAhcm -2 After 50 cycles at the current density, Comparative Example 1 showed obvious growth and irregularity of zinc dendrites, while Example 1 showed uniform zinc deposition compared to Comparative Example 1.

[0031] Example 2: The aqueous zinc-ion battery of this embodiment is prepared through the following steps: S1 cuts 50μm thick zinc foil into 5cm*5cm electrode sheets, lays them flat on the heating table, and heats them at 150℃. S2 dissolves 90mg InMOF nanoparticles and 10mg PVDF in 3mL NMP, stirs at 150-250rpm and sonicates for 24h, injects the resulting coating slurry into a spray gun, sprays it onto the 5cm*5cm zinc metal electrode sheet, and then places it in a vacuum drying oven at 100℃ for 12h. S3 cuts the above-sprayed zinc foil into electrode sheets with a diameter of 12mm, and presses them under a pressure of 5MPa to obtain zinc metal electrode sheets with InMOF coating. S4 is assembled into a zinc-zinc symmetrical battery by comprising a positive electrode shell, copper foil (positive electrode), separator, electrolyte, coated zinc foil, gasket, spring sheet, and negative electrode shell.

[0032] Comparative Example 2: The difference from Example 2 is that the preparation method of the zinc anode was changed, and the InMOF nanoparticle coating was not added. The specific method is as follows: Q1 cuts a 50μm thick zinc foil into 12mm diameter electrode sheets, presses them under a pressure of 5MPa, then places the zinc sheets in an ethanol solution, sonicates them for 5 minutes, and dries them naturally in air to obtain zinc electrode sheets, which serve as the negative electrode of the battery. Q2 cuts a 20μm thick copper foil into 14mm diameter electrode sheets, presses them under 5MPa pressure, then places the copper sheets in an ethanol solution, sonicates for 5min, and air-dries them to obtain the positive electrode sheet. Q3 Assemble a zinc-copper asymmetric battery according to the positive electrode shell, copper foil, separator, electrolyte, zinc foil, gasket, spring sheet and negative electrode shell.

[0033] The test schemes and analysis results of Example 2 and Comparative Example 2 are as follows: The zinc-copper asymmetric cells assembled in Example 2 and Comparative Example 2, at 2 mA cm⁻¹ -2 2mAh cm -2 Cycling is performed at current densities. Figure 4 The zinc-copper asymmetric cells assembled in Example 2 and Comparative Example 2 are shown at 2 mA cm⁻¹. -2 2mAh cm -2 The cycle life at current density showed that Example 2 had a stable cycle life of over 1200 cycles, while Comparative Example 2 only achieved a stable cycle life of 50 cycles, indicating that Example 2 has a longer cycle life than Comparative Example 2.

[0034] Example 3: The aqueous zinc-ion battery of this embodiment is prepared through the following steps: (1) Preparation of positive electrode: Vanadium pentoxide (V2O5) positive electrode preparation: weigh ammonium metavanadate, heat it to 400 degrees Celsius at 10℃ per minute, keep it in a muffle furnace for 1 hour and then cool it naturally to room temperature to obtain V2O5 golden yellow powder; V₂O₅ powder, conductive carbon black, and polyvinylidene fluoride were mixed in N-methylpyrrolidone at a weight ratio of 7:2:1 to form a slurry, which was then coated onto Ti foil and dried in a vacuum oven at 80°C for later use. The mass loading of V₂O₅ on the electrode was 1~1.5 mg / cm³. -2 .

[0035] (2) Preparation of negative electrode sheet: S1 cuts 50μm thick zinc foil into 5cm*5cm electrode sheets, lays them flat on the heating table, and heats them at 150℃ to ensure that NMP evaporates rapidly during the spraying process. S2 dissolves 90mg InMOF nanoparticles and 10mg PVDF in 3mL NMP, stirs at 150-250rpm and sonicates for 24h, injects the resulting coating slurry into a spray gun, sprays it onto the 5cm*5cm zinc metal electrode sheet, and then places it in a vacuum drying oven at 100℃ for 12h. S3 cuts the above-sprayed zinc foil into electrode sheets with a diameter of 12mm, and presses them under a pressure of 5MPa to obtain zinc metal electrode sheets with InMOF coating.

[0036] (3) Assemble the battery in the following order: positive electrode shell, positive electrode sheet, separator, electrolyte, coated zinc negative electrode sheet, gasket, spring sheet and negative electrode shell, and press the battery with a press machine.

[0037] Comparative Example 3: The difference from Example 3 is that the zinc anode does not have an InMOF nanoparticle coating, but the other steps are the same.

[0038] Figure 5 The batteries assembled for Example 3 and Comparative Example 3, with a capacity of 5 A·g -1 The cycle performance curve of current density discharge is derived from... Figure 5 As can be seen, the battery of Example 3 has a capacity retention rate of over 80% and a coulombic efficiency of over 99% after 1200 cycles; the battery assembled in Comparative Example 3 has a capacity retention rate of much lower than that of Example 3 after 1200 cycles.

[0039] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a zinc anode for aqueous zinc-ion batteries, characterized in that, The application relates to a preparation method of a water-based zinc ion battery zinc negative electrode. Preparation of a coating slurry comprising InMOF nanoparticles, a solvent and a binder; Heating a zinc negative electrode sheet to 140-160 DEG C; Spraying the coating slurry to the surface of the zinc negative electrode sheet, and then drying, so that the zinc negative electrode with an MOF coating is obtained through pyrolysis of the coating slurry.

2. The method for preparing a zinc anode for aqueous zinc-ion batteries according to claim 1, characterized in that, The solvent is N-methyl pyrrolidone, and the concentration is greater than or equal to 99.9%.

3. The method of producing a zinc anode for aqueous zinc-ion batteries according to claim 1, wherein The binder is polyvinylidene fluoride.

4. The method of producing a zinc anode for aqueous zinc-ion batteries according to claim 1, wherein The loading amount of the InMOF nanoparticles on the zinc negative electrode is 0.5-2 mg / cm 2 .

5. The method of producing a zinc anode for aqueous zinc-ion batteries according to claim 1, wherein The mass ratio of the InMOF nanoparticles, the solvent and the binder is 25-90 mg:2.5-10 mg:2-3 mL.

6. The zinc negative electrode prepared by the preparation method of the water-based zinc ion battery zinc negative electrode according to any one of claims 1-5.

7. The zinc anode for aqueous zinc-ion batteries prepared by the method of any one of claims 1-5 for use in an aqueous zinc-ion battery, characterized in that, The water-based zinc ion battery preparation method comprises the following steps: (1) uniformly mixing a positive electrode material, conductive carbon black and a binder to obtain a slurry, uniformly applying the slurry on a current collector, and drying to obtain a positive electrode sheet; (2) assembling a negative electrode shell, a zinc negative electrode, a separator, an electrolyte, the positive electrode sheet, a gasket, an elastic sheet and a positive electrode shell to obtain the water-based zinc ion battery.

8. The aqueous zinc-ion battery production method of claim 7, wherein, In step (1), the mass ratio of the positive electrode material, the conductive carbon black and the binder is 70-80%:10-20%:10%; and the positive electrode material is at least one of vanadium pentoxide and ammonium vanadate.

9. The aqueous zinc ion battery production method of claim 7, wherein, The electrolyte solute is at least one of ZnOTF and ZnSO4.

10. The aqueous zinc ion battery production method of claim 7, wherein, The application thickness of the slurry is 100-150 mu m.

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