Method for producing zinc negative electrode with hydrophobic conductive polymer film and use thereof

Abstract

This invention belongs to the field of energy materials technology, specifically relating to a method for preparing and applying a zinc anode with a hydrophobic conductive polymer film. The main aim is to solve problems such as severe zinc dendrite formation, low coulombic efficiency, poor cycle performance, inability to perform deep charge-discharge, and poor safety performance caused by uneven zinc deposition. The main solution involves adsorbing a poly(3,4-ethylenedioxythiophene) (PEDOT) film, prepared by ion-directed diffusion, onto the surface of the zinc anode in an aqueous zinc-ion battery as a protective layer. This film possesses a certain degree of hydrophobicity, enhancing the hydration of Zn. 2+ The desolvation reaction effectively inhibits corrosion and electrochemical hydrogen evolution on the zinc anode surface, while also suppressing zinc dendrite formation and increasing ion diffusion rate, significantly improving its structural and performance stability. Compared with traditional anode protection strategies, it has advantages such as simplicity, high efficiency, sustainability, low cost, and wide applicability, enabling its application in various aqueous batteries.

Description

Technical Field

[0001] This invention belongs to the field of energy materials technology, specifically relating to a method for preparing and applying a zinc anode with a hydrophobic conductive polymer film. Background Technology

[0002] Benefiting from high energy density and long-term cycle stability, lithium-ion batteries have been widely commercialized as power systems for portable electronic devices and electric vehicles. However, three major obstacles—safety concerns, high price, and resource scarcity—severely hinder their practical application. Recently, aqueous metal-ion batteries (such as Na+) have emerged as a potential solution. + K + Zn 2+ Mg 2+ Al 3+ (etc.). Due to its non-flammability, high ionic conductivity (three orders of magnitude higher than organic electrolytes), environmental friendliness, and low cost, it is considered a promising alternative to lithium-ion batteries. In particular, rechargeable zinc-ion water batteries are considered promising due to their excellent theoretical capacity (820 mAh g⁻¹). -1 Or 5855mAhcm -3 The low redox potential (-0.76V vs standard hydrogen electrode), the natural abundance of zinc resources, and the stability of metallic zinc anodes have attracted widespread attention.

[0003] However, the unstable interface, due to severe side reactions and dendritic growth, significantly hinders the large-scale application of aqueous zinc-ion batteries. Firstly, due to the Zn / Zn... 2+ The standard electrode potential is lower than H2 / H + Therefore, during the cycle, the reduction of pure zinc metal is accompanied by the decomposition of water (hydrogen evolution reaction). This phenomenon produces hydrogen gas, making the zinc-metal surface unstable. Simultaneously, the hydrogen evolution reaction can generate hydroxide ions as a byproduct on the zinc-metal surface, thus forming inactive Zn(OH)4. 2-Firstly, the zinc dendrites consume both the zinc anode and electrolyte. Secondly, the disordered zinc dendrites perpendicular to the coating / stripping substrate result in a loose, porous structure. This not only produces "dead zinc," reducing the coulombic efficiency and capacity of aqueous zinc-ion batteries, but also provides more reaction sites to accelerate the aforementioned side reactions due to the high specific surface area between the electrode and electrolyte. Therefore, solving the zinc dendrite problem has always been a core issue in the research of zinc anode batteries. However, most current research on artificial protective layers focuses on testing low current and low discharge areal capacity, which cannot meet the requirements of high energy density and power density in practical applications. Invention patent CN109980226A discloses a zinc anode with a polyamide brightener layer and its preparation method, but this process can only improve the lifespan of the zinc anode under low current density and low areal capacity. Invention patent CN108520985A discloses a method to improve the cycle life of zinc electrodes. This invention has a simple process and low cost, but the cycle life of the zinc electrode prepared by this process is still less than 100 hours, and it cannot solve the chemical and electrochemical corrosion of the zinc anode. Therefore, it is crucial to obtain a zinc anode that can cycle stably under high current density using a low-cost and simple preparation process. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of severe zinc dendrite formation, low coulombic efficiency, poor cycle performance, inability to perform deep charge and discharge, and poor safety performance caused by uneven deposition of zinc metal.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing a zinc anode with a hydrophobic conductive polymer film includes the following steps:

[0007] 1) Immerse the zinc anode in a salt solution containing metal cations for a certain period of time to obtain a zinc anode with a thin film of salt solution adsorbed on its surface;

[0008] 2) Immerse the zinc anode with a thin film of salt solution adsorbed on its surface in a poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) dispersion treated with organic solvent for a certain period of time to obtain a zinc anode with a poly(3,4-ethylenedioxythiophene) liquid film adsorbed on its surface. In this step, the subsequent work needs to be completed within half an hour after the organic solvent treatment, otherwise it will affect the removal effect of poly(styrene sulfonate) and ultimately affect the conductivity of the protective layer.

[0009] 3) The zinc anode with a poly(3,4-ethylenedioxythiophene) liquid film adsorbed on its surface is placed in an oven and dried to obtain a zinc anode with a poly(3,4-ethylenedioxythiophene) thin film protective layer.

[0010] Specifically, in step 1), the salt solution containing metal cations is a hydrochloride or sulfate of divalent metal cations such as barium, calcium, or zinc; the concentration of the salt solution containing metal cations is 0.1, 0.5, 1, or 2 mol / L.

[0011] Specifically, in step 1), the specified time is 5-20 seconds, with 10 seconds being preferred;

[0012] Specifically, in step 2), the concentration of the poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) dispersion is 2-10 mg / L;

[0013] Specifically, in step 2), the specified time is 5-20 seconds, with 10 seconds being preferred.

[0014] Specifically, in step 2), the organic solvent includes one of methanol, ethylene glycol, N,N-dimethylformamide, and dimethyl sulfoxide;

[0015] Specifically, in step 3), the drying temperature is 50-60℃ and the drying time is 1-2 hours;

[0016] Specifically, in step 3), the thickness of the film is 2-10 μm.

[0017] In this invention, the zinc anode with a hydrophobic conductive polymer film not only avoids direct contact between the zinc anode and the electrolyte, but also enhances the hydration of Zn. 2+ The desolvation behavior prevents the occurrence of hydrogen evolution reaction on the zinc surface and the generation of by-products. Simultaneously, its porous structure and the pre-retained Zn... 2+ The conductive polymer film acts as a bridge in the network channel, improving the ion diffusion rate and making zinc deposition more uniform. In addition, the conductive polymer film has good stability, inhibiting the growth of zinc dendrites, thereby greatly improving the cycle life of zinc-based batteries.

[0018] The second technical solution of the present invention proposes an aqueous secondary battery, including a positive electrode, a zinc negative electrode made of zinc negative electrode material as described above, a separator, and an electrolyte. The zinc negative electrode and the positive electrode are respectively located on both sides of the separator, and a hydrophobic conductive polymer film on one side of the zinc negative electrode is adjacent to the separator.

[0019] Furthermore, the positive electrode sheet includes, but is not limited to, manganese dioxide positive electrode sheet, vanadium pentoxide positive electrode sheet, Prussian blue positive electrode sheet, lithium manganese oxide positive electrode sheet, and polyaniline positive electrode sheet.

[0020] Furthermore, the diaphragm includes, but is not limited to, glass fiber diaphragms, PP diaphragms, PE diaphragms, and filter paper diaphragms.

[0021] Furthermore, the solute in the electrolyte includes, but is not limited to, at least one of zinc sulfate, zinc trifluoromethanesulfonate, zinc perchlorate, and zinc chloride; the solvent in the electrolyte is ultrapure water; the amount and concentration of the electrolyte are those conventionally used in the art, generally 60-100 μL.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] (1) In the case of aqueous electrolyte environment, the hydrogen evolution reaction and side reaction between zinc electrode and electrolyte are greatly suppressed in the high current density and current surface capacity charge and discharge test, greatly reducing the generation of "dead zinc", the stability of the electrode-electrolyte interface is significantly improved, zinc ions have a higher transport rate, the deposition process on zinc electrode is effectively controlled, uniform and dense (002) crystal plane deposition is achieved, the generation of zinc dendrites is avoided, thereby improving the coulombic efficiency and cycle life of symmetric zinc ion battery, as well as improving the capacity retention rate and cycle life of aqueous zinc ion battery.

[0024] (2) The preparation process is simple, the cost is low, and it is easy to produce on a large scale, so as to realize an ultra-thin (<10μm) artificial interface modified protective layer.

[0025] (3) The technical solution of the present invention constructs a hydrophobic conductive polymer film on the surface of the zinc anode, which not only avoids direct contact between the zinc anode and the electrolyte, but also enhances the hydration of Zn. 2+ The desolvation behavior prevents the occurrence of hydrogen evolution reaction on the zinc surface and the generation of by-products. Simultaneously, its porous structure and the pre-retained Zn... 2+ The conductive polymer film acts as a bridge in the network channel, improving the ion diffusion rate and thus reducing the nucleation overpotential, resulting in more uniform zinc deposition. At the same time, the conductive polymer film has excellent conductivity, which helps to uniformly shape the electric field on the zinc anode surface and promotes uniform zinc ion deposition. In addition, the conductive polymer film has good stability, which inhibits the growth of zinc dendrites, thereby greatly improving the cycle life of zinc-based batteries. Attached Figure Description

[0026] Appendix Figure 1 Schematic diagram of the internal structure of the battery

[0027] Appendix Figure 2 The zinc anode with a hydrophobic conductive polymer film provided in Example 1 of the present invention and the zinc anode of Comparative Example 1 are compared at 5 mA / cm. -2 Polarization voltage-cycle time plot of charge-discharge test at current density;

[0028] Appendix Figure 3 The zinc anode with a hydrophobic conductive polymer film provided in Example 2 of the present invention and the zinc anode in Comparative Example 2 are compared at 5 mA / cm.-2 Polarization voltage-cycle time plot of charge-discharge test at current density;

[0029] Appendix Figure 4 The zinc anode with a hydrophobic conductive polymer film provided in Example 3 of the present invention and the zinc anode of Comparative Example 3 are compared at 5 mA / cm. -2 Polarization voltage-cycle time plot of charge-discharge test at current density;

[0030] Appendix Figure 5 X-ray diffraction (XRD) patterns of the zinc anode with an elastic protective layer provided in Embodiment 3 of the present invention and the zinc anode of Comparative Example 3 after 100 cycles.

[0031] Appendix Figure 6 Scanning electron microscope (SEM) images of the electrodeposition morphology of the zinc anode with an elastic protective layer provided in Embodiment 3 of the present invention and the zinc anode of Comparative Example 3 after 100 cycles.

[0032] Explanation of reference numerals in the attached figures:

[0033] 1-Negative electrode shell, 2-Spring sheet, 3-First gasket, 4-First zinc foil, 5-First protective layer, 6-Separator, 7-Second protective layer, 8-Second zinc foil, 9-Second gasket, 10-Positive electrode shell. Detailed Implementation

[0034] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0035] The following embodiments are only used to explain the present invention. The specific implementation of the present invention is not limited to these descriptions. Any deductions, modifications or substitutions made under the premise of the concept of the present invention shall be considered as the protection scope of the claims submitted by the present invention.

[0036] Since the improvement of this invention only relates to the zinc negative electrode of a zinc-based battery, the positive electrode, separator, and electrolyte in the zinc secondary battery provided by this invention are all types of positive electrodes, separators, and aqueous electrolytes used in conventional zinc-based secondary batteries. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0037] Example 1

[0038] The method for preparing the zinc anode with a hydrophobic conductive polymer film in this embodiment includes the following steps:

[0039] S1. The zinc anode is immersed in a zinc sulfate solution with a concentration of 1 mol / L for 10 s to obtain a zinc anode with a thin film of salt solution adsorbed on its surface.

[0040] S2. The zinc anode with a thin film of salt solution adsorbed on its surface is immersed in a poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) dispersion with a concentration of 10 mg / ml treated with dimethyl sulfoxide for 10 s to obtain a zinc anode with a poly(3,4-ethylenedioxythiophene) liquid film adsorbed on its surface.

[0041] S3. The zinc anode with a poly(3,4-ethylenedioxythiophene) liquid film adsorbed on its surface is placed in a 55°C oven and dried for 1.5 hours to obtain a zinc anode with a poly(3,4-ethylenedioxythiophene) thin film protective layer.

[0042] S4 uses a 2 mol / L ZnSO4 aqueous solution as the electrolyte and a glass fiber membrane to assemble a Zn||Zn symmetric cell according to conventional battery assembly methods in the art. At 5 mA / cm²... -2 Charge-discharge tests were performed at current densities, as shown in the attached figure. Figure 2 As shown.

[0043] Comparative Example 1

[0044] Untreated zinc sheets were used as electrolytes, and a Zn||Zn symmetric cell was assembled using a glass fiber membrane and conventional battery assembly methods in the art. The cell was tested at 5 mA / cm². -2 Charge-discharge tests were performed at current densities, as shown in the attached figure. Figure 2 As shown, the Zn||Zn symmetric cell assembled with a zinc anode having a hydrophobic conductive polymer film in Example 1 has a lower cycle overpotential and a longer lifespan than that in Comparative Example 1.

[0045] Example 2

[0046] The method for preparing the zinc anode with a hydrophobic conductive polymer film in this embodiment includes the following steps:

[0047] S1. The zinc anode is immersed in a zinc sulfate solution with a concentration of 1 mol / L for 10 s to obtain a zinc anode with a thin film of salt solution adsorbed on its surface.

[0048] S2. The zinc anode with a thin film of salt solution adsorbed on its surface is immersed in a poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) dispersion with a concentration of 6 mg / ml treated with dimethyl sulfoxide for 10 s to obtain a zinc anode with a poly(3,4-ethylenedioxythiophene) liquid film adsorbed on its surface.

[0049] S3. The zinc anode with a poly(3,4-ethylenedioxythiophene) liquid film adsorbed on its surface is placed in a 55°C oven and dried for 1.5 hours to obtain a zinc anode with a poly(3,4-ethylenedioxythiophene) thin film protective layer.

[0050] S4 uses a 2 mol / L ZnSO4 aqueous solution as the electrolyte and a glass fiber membrane to assemble a Zn||Zn symmetric cell according to conventional battery assembly methods in the art. At 5 mA / cm²... -2 Charge-discharge tests were performed at current densities, as shown in the attached figure. Figure 3 As shown.

[0051] Comparative Example 2

[0052] Untreated zinc sheets were used as electrolytes, and a Zn||Zn symmetric cell was assembled using a glass fiber membrane and conventional battery assembly methods in the art. The cell was tested at 5 mA / cm². -2 At a current density of 1 mAh cm⁻¹ -2 Charge and discharge tests were performed at the specified capacity, as shown in the attached document. Figure 3 As shown, the Zn||Zn symmetric cell assembled with a zinc anode having a hydrophobic conductive polymer film in Example 2 has a lower cycle overpotential and a longer lifespan than that in Comparative Example 2.

[0053] Example 3

[0054] The method for preparing the zinc anode with a hydrophobic conductive polymer film in this embodiment includes the following steps:

[0055] S1. The zinc anode is immersed in a zinc sulfate solution with a concentration of 1 mol / L for 10 s to obtain a zinc anode with a thin film of salt solution adsorbed on its surface.

[0056] S2. The zinc anode with a thin film of salt solution adsorbed on its surface is immersed in a poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) dispersion with a concentration of 2 mg / ml treated with dimethyl sulfoxide for 10 s to obtain a zinc anode with a poly(3,4-ethylenedioxythiophene) liquid film adsorbed on its surface.

[0057] S3. The zinc anode with a poly(3,4-ethylenedioxythiophene) liquid film adsorbed on its surface is placed in a 55°C oven and dried for 1.5 hours to obtain a zinc anode with a poly(3,4-ethylenedioxythiophene) thin film protective layer.

[0058] S4 uses a 2 mol / L ZnSO4 aqueous solution as the electrolyte and a glass fiber membrane to assemble a Zn||Zn symmetric cell according to conventional battery assembly methods in the art. At 5 mA / cm²... -2 Charge-discharge tests were performed at current densities, as shown in the attached figure. Figure 4As shown in the attached figure. X-ray diffraction (XRD) analysis of the zinc sheet was performed after 100 cycles. Figure 5 As shown in the attached figure. The microstructure of the recycled zinc sheet was observed using a scanning electron microscope. Figure 6 As shown on the right.

[0059] Comparative Example 3

[0060] Untreated zinc sheets were used as electrolytes, and a Zn||Zn symmetric cell was assembled using a glass fiber membrane and conventional battery assembly methods in the art. The cell was tested at 5 mA / cm². -2 Charge-discharge tests were performed at current densities, as shown in the attached figure. Figure 4 As shown, the Zn||Zn symmetric cell assembled with a zinc anode using a hydrophobic conductive polymer film in Example 3 has a lower cycling overpotential and longer lifespan than that in Comparative Example 3. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were performed on the zinc sheet after 100 cycles, as shown in the attached figure. Figure 5 and attached Figure 6 As shown on the left, the side reactions of the Zn||Zn symmetric cell assembled with a zinc anode with a protective layer were significantly suppressed after 100 cycles. In the Zn||Zn symmetric cell assembled with a zinc anode with a protective layer, after cycling, the electrodeposited zinc was uniformly deposited on the zinc sheet, while in the unprotected zinc sheet, the electrodeposited zinc was randomly piled up on the surface of the zinc sheet. It can be seen that the elastic protective layer can effectively regulate the electrodeposition of zinc ions and avoid the formation of zinc dendrites.

[0061] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a zinc anode with a hydrophobic conductive polymer film, characterized in that, Includes the following steps: Step 1) Immerse the zinc anode in a 1 mol / L zinc sulfate solution for 5-20 seconds to allow cations to adsorb onto the zinc anode surface and act as crosslinking agents, thus obtaining a zinc anode with a thin film of salt solution adsorbed on its surface. Step 2) Immerse the zinc anode with a thin film of salt solution adsorbed on its surface in a poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate), i.e., PEDOT:PSS dispersion treated with the organic solvent dimethyl sulfoxide for 5-20 seconds. The cations in the salt solution film diffuse directionally into the dispersion, shielding the electrostatic repulsion between the microgel particles, causing the particles to aggregate and form a three-dimensional network protective layer through physical cross-linking and π-π stacking interactions. This layer is adsorbed tightly onto the surface of the zinc anode, resulting in a zinc anode with a surface-adsorbed poly(3,4-ethylenedioxythiophene), i.e., PEDOT liquid film. Step 3) Place the zinc anode with the poly(3,4-ethylenedioxythiophene) liquid film adsorbed on its surface into an oven and dry it at 55°C for 1.5 hours to obtain a zinc anode with a poly(3,4-ethylenedioxythiophene) thin film protective layer.

2. The method of producing a zinc negative electrode having a hydrophobic conductive polymer film according to claim 1, wherein In step 2), the concentration of the poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) dispersion is 2-10 mg / mL.

3. The method for preparing a zinc anode with a hydrophobic conductive polymer film as described in claim 1, characterized in that, In step 3), the thickness of the film is 2-10 μm.

4. A zinc anode having a hydrophobic conductive polymer film prepared by the method according to any one of claims 1-3.

5. An aqueous secondary battery comprising a positive electrode, a separator, an electrolyte, and a zinc negative electrode having a hydrophobic conductive polymer film according to claim 4, characterized by The zinc negative electrode and positive electrode are located on opposite sides of the separator, and the thin film on the surface of the zinc negative electrode is close to the separator.

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