Functional synergistic gradient interface modified zinc negative electrode and preparation method and application thereof

Abstract

This invention belongs to the field of zinc anode technology, specifically relating to a functionally synergistic gradient interface modified zinc anode, its preparation method, and its application. The anode includes a zinc substrate and a gradient interface layer formed on the surface of the zinc substrate. The gradient interface layer comprises an inorganic layer closely adhering to the zinc substrate and an organic layer closely adhering to the inorganic layer. The organic layer is porous. The inorganic layer comprises zinc fluoride. The zinc anode of this invention can synergistically regulate Zn content. 2+ The transport kinetics and nucleation thermodynamics inhibit dendrite growth, hydrogen evolution and corrosion, and block the migration of corrosive species from the positive electrode, such as polyiodide ions, to the negative electrode, making it suitable for zinc-iodine batteries and other aqueous zinc batteries.

Description

Technical Field

[0001] This invention belongs to the field of zinc anode technology, specifically relating to a method for modifying zinc anodes with a functional synergistic gradient interface. Background Technology

[0002] Aqueous zinc metal batteries possess advantages such as high safety, low cost, abundant zinc resources, and high theoretical capacity, making them promising candidates for large-scale energy storage and safe energy storage devices. However, zinc anodes are prone to problems such as dendrite growth, hydrogen evolution, and interface corrosion during repeated deposition / stripping processes, severely impacting the battery's cycle life and safety.

[0003] Existing interfacial modification strategies for zinc anodes mostly focus on optimizing a single step, such as improving ion transport, increasing surface zinc affinity, or suppressing side reactions. Since zinc deposition inherently involves Zn... 2+ Multiple continuous processes, such as transport, desolvation, nucleation, and growth, often make it difficult to fundamentally solve the dendrite problem caused by uneven zinc anode deposition by controlling only a single process.

[0004] Furthermore, in full-cell systems employing soluble halogen active species such as zinc-iodine batteries, corrosive species such as polyiodide ions generated during cycling can migrate towards the zinc anode, initiating chemical corrosion and parasitic reactions, and accelerating interfacial instability. Therefore, developing an interfacial structure that can synergistically regulate Zn2+ transport kinetics and nucleation thermodynamics while blocking the migration of corrosive species from the cathode is of great significance for improving the cycle stability and practical application of aqueous zinc metal batteries. Summary of the Invention

[0005] This invention mainly provides a functionally synergistic gradient interface modified zinc anode and a battery made using this anode, to solve the problems of dendrite growth, hydrogen evolution, severe side reactions, and polyiodine ion corrosion of the anode in zinc-iodine full cells in the prior art. The technical solution is as follows:

[0006] A functionally synergistic gradient interface modified zinc anode includes a zinc substrate and a gradient interface layer formed on the surface of the zinc substrate; the gradient interface layer includes an inorganic layer closely adhering to the zinc substrate and an organic layer closely adhering to the inorganic layer; the organic layer is porous; the inorganic layer includes zinc fluoride.

[0007] Furthermore, the inorganic layer is formed by a chemical reaction between silver ions and a zinc matrix.

[0008] A method for preparing the above-mentioned functionally synergistic gradient interface modified zinc anode includes the following steps: dissolving a silver compound and a polymer in an organic acid to obtain a coating solution; fully covering the zinc substrate surface with the coating solution and then drying it; causing zinc compounds to be generated in situ on the zinc substrate surface to form an inorganic layer, and the polymer to be deposited on the outermost layer to form an organic layer.

[0009] Furthermore, the fluorine compound includes one or more of silver fluoride, copper fluoride, tin fluoride, nickel fluoride, or cobalt fluoride; the polymer includes one or more of polyamide, polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, polyacrylic acid, or polyethylene oxide.

[0010] Furthermore, the organic acid includes one or more of formic acid, trifluoroacetic acid, dichloroacetic acid, or chloroacetic acid.

[0011] Furthermore, the concentration of the silver compound in the coating solution is 5-10 mmol / L; the concentration of the polymer in the coating solution is 0.05-0.2 g / mL.

[0012] Furthermore, the drying temperature is 60~80℃, and the time is 8~12h.

[0013] The above-mentioned functional synergistic gradient interface modification of zinc anodes is applied in batteries, capacitors, or supercapacitors.

[0014] A battery prepared by modifying a zinc anode with the above-mentioned functional synergistic gradient interface, the battery comprising a symmetrical battery, a half-cell, or a full-cell.

[0015] Furthermore, the battery is a zinc-iodine battery, with the positive electrode being an iodine positive electrode or a halogen positive electrode containing polyiodine ions that can be reversibly converted.

[0016] By adopting the above scheme, the method of the present invention has the following advantages:

[0017] 1. In this invention, the inorganic layer chemical replacement and organic layer film formation on the zinc anode surface are carried out simultaneously, ensuring the formation of a continuously distributed, tightly bonded, structurally stable, and high-strength organic-inorganic gradient interface, and fully dispersing the zinc compounds in the inorganic layer, thus ensuring the structural integrity of the zinc anode, improving ion transport speed, electrochemical reaction uniformity and stability, and cycle life.

[0018] 2. The organic layer on the surface of the zinc anode of the present invention has a porous structure, which can improve the wettability of the electrode surface and induce Zn 2+ Preferred coordination; the inorganic layer of zinc compound is in direct contact with the zinc matrix, which can provide zinc-loving sites and ordered ion transport channels; the gradient interface formed can simultaneously inhibit dendrite growth, hydrogen evolution and corrosion, and form a barrier to corrosive species from the positive electrode such as polyiodide ions, thereby significantly improving the cycle stability of symmetric cells, half cells and full cells.

[0019] 3. The polyamide organic layer on the surface of the zinc anode of the present invention can promote the growth of Zn through polar functional groups. 2+ Preferential coordination and improved interfacial wettability reduce local concentration polarization; the zinc fluoride inner layer has strong zinc affinity, which can lower the nucleation energy barrier and induce uniform nucleation, while also providing Zn with a favorable environment for nucleation. 2+ Provides a low-impedance interface migration path.

[0020] 4. The symmetrical cell prepared by the zinc negative electrode of the present invention has a performance of 1 mA cm⁻¹ -2 1 mAh cm -2 Under certain conditions, it can be stably cycled for more than 1800 h, which is significantly better than bare Zn anode and gradient interface anode prepared by stepwise method; indicating that the organic-inorganic gradient interface constructed by the one-step method of the present invention can more effectively improve the deposition / stripping stability of zinc anode and suppress dendrite growth.

[0021] 5. The zinc-iodine full cell constructed using the zinc anode of this invention at 1 A g -1 It retains approximately 80% of its capacity after 6500 cycles under certain conditions, demonstrating promising application prospects. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the preparation process of the functional synergistic gradient interface modified zinc anode in Example 1;

[0023] Figure 2 This is a scanning electron microscope image of the functional synergistic gradient interface modified zinc anode of Example 1;

[0024] Figure 3 This is a comparison diagram of zinc deposition nucleation on the zinc anode modified by the functional synergistic gradient interface of the present invention;

[0025] Figure 4 The symmetrical cells prepared from the zinc anodes obtained in Examples 1 and 1-3 were used in 1 mA cm⁻¹ -2 1 mAh cm -2 Constant current charge-discharge curves under the specified conditions;

[0026] Figure 5 The symmetrical cells prepared from the zinc anodes obtained in Example 1 (one-step method) and Comparative Example 4 (step-by-step method) are measured at 1 mAcm. -2 1 mAh cm -2 Constant current charge-discharge curves under the specified conditions;

[0027] Figure 6 This is a long-cycle comparison diagram of the symmetrical cells prepared with zinc anodes in Example 1 and Comparative Example 1.

[0028] Figure 7This is a long-cycle comparison diagram of the full cells prepared with zinc anodes in Example 1 and Comparative Example 1. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1: According to Figure 1 0.005 g of silver fluoride powder and 0.5 g of polyamide powder were weighed and added to 5 mL of anhydrous formic acid, stirred and dissolved to obtain an AgF-PA coating solution. The AgF-PA coating solution was then coated onto the surface of a zinc foil and dried at 70 °C for 10 h. During the drying process, the zinc foil and AgF underwent a simultaneous displacement reaction, forming an inner ZnF2 layer in situ on the zinc foil surface, while the polyamide was deposited to form an outer layer, thus constructing a functionally synergistic gradient interface modified zinc anode (SGI@Zn) in one step. The scanning electron microscope image of the prepared zinc anode is shown below. Figure 2 As shown in the figure, multiple large pores of uniform size are evenly distributed on the material, and there are also densely packed interconnected nanopores with extremely small diameters, indicating that the prepared zinc anode material has a very large surface area.

[0031] Comparative Example 1: The difference from Example 1 is that:

[0032] Unmodified zinc foil was used as the bare Zn anode.

[0033] Comparative Example 2: 0.005 g of silver fluoride powder was weighed and added to 5 mL of anhydrous formic acid to obtain AgF coating solution; the coating solution was scraped onto the surface of zinc foil and dried at 70°C for 10 h to obtain ZnF2@Zn anode containing only zinc fluoride layer.

[0034] Comparative Example 3: 0.5 g of polyamide powder was weighed and added to 5 mL of anhydrous formic acid to obtain a PA coating solution; the coating solution was scraped onto the surface of zinc foil and dried at 70 °C for 10 h to obtain a PA@Zn anode containing only a polyamide outer layer.

[0035] Comparative Example 4: A stepwise method was used to prepare a gradient interface-modified zinc anode. First, 0.005 g of silver fluoride powder was weighed and added to 5 mL of anhydrous formic acid, and stirred to dissolve, obtaining an AgF coating solution. The AgF coating solution was then coated onto the surface of a zinc metal substrate and dried at 70 °C for 10 h to obtain a ZnF2@Zn anode. Next, 0.5 g of polyamide powder was weighed and added to 5 mL of anhydrous formic acid, and stirred to dissolve, obtaining a PA coating solution. The PA coating solution was then coated onto the surface of the previously prepared ZnF2@Zn anode and dried at 70 °C for 10 h to obtain a zinc anode prepared by the stepwise method. During the preparation process, the formation of the zinc fluoride layer and the deposition of the polyamide layer occurred sequentially.

[0036] Example Sample Testing:

[0037] Zinc deposition nucleation was performed on the zinc anodes obtained in Example 1 and Comparative Example 1, and the results are as follows: Figure 3 As shown in the figure. The results indicate that the zinc anode of the present invention has stronger interfacial zinc affinity and lower nucleation overpotential, which can induce more uniform zinc deposition.

[0038] Zn||Zn symmetric cells were assembled using the zinc anodes obtained in Example 1 and each comparative example, respectively, at 1 mA cm⁻¹. -2 1 mAhcm -2 A constant current charge-discharge test was performed under the specified conditions, and the test results are as follows: Figure 4 and Figure 5 As shown. Figure 4 The results show that the bare Zn symmetric cell short-circuited within about 200 h; the PA@Zn symmetric cell had a shorter cycle life due to its larger polarization; and the ZnF2@Zn symmetric cell could cycle stably for about 1000 h. Therefore, the symmetric cell constructed by modifying the zinc anode with the functionally synergistic gradient interface of this invention can cycle stably for more than 1800 h, indicating that the constructed organic-inorganic gradient interface can significantly improve the deposition / stripping stability of the zinc anode and effectively suppress dendrite growth. Figure 5 The results show that the zinc electrode prepared by the stepwise method can only cycle stably for about 900 h; the symmetric battery constructed by the zinc anode modified with the functional synergistic gradient interface of the present invention can cycle stably for more than 1800 h. These results indicate that, compared with the stepwise method, the organic-inorganic gradient interface constructed by the one-step method of the present invention can more effectively improve the deposition / stripping stability of the zinc anode and inhibit dendrite growth. This suggests that the simultaneous chemical replacement and film formation processes are one of the decisive factors in forming a gradient interface structure with superior performance.

[0039] Cyclic stability tests were performed on the zinc anodes obtained in Example 1 and Comparative Example 1, and the results are as follows: Figure 6 As shown, in Zn||Cu half-cells and Zn||Zn symmetric cells, the zinc anode of this invention exhibits higher coulombic efficiency and longer stable cycle life.

[0040] Full cells were constructed using the zinc anodes obtained in Example 1 and Comparative Example 1, respectively, and combined with iodine cathodes. The test results are as follows: Figure 7 As shown. The results indicate that the gradient interface of this invention can effectively block the migration of corrosive species from the positive electrode, such as polyiodide ions, to the negative electrode; the assembled zinc-iodine full cell can withstand 1 A g. -1 After 6500 cycles under certain conditions, the capacity retention rate is still about 80%, indicating that the present invention has good application prospects.

[0041] For those skilled in the art, various other corresponding changes and modifications can be made based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of this invention.

Claims

1. A functionally synergistic gradient interface modified zinc anode, characterized in that, It includes a zinc substrate and a gradient interface layer formed on the surface of the zinc substrate; the gradient interface layer includes an inorganic layer in close contact with the zinc substrate and an organic layer in close contact with the inorganic layer; the organic layer is porous; the inorganic layer includes zinc fluoride.

2. The functionally synergistic gradient interface modified zinc anode according to claim 1, characterized in that, The inorganic layer is formed by a chemical reaction between a fluorine compound and a zinc matrix.

3. A method for preparing a functionally synergistic gradient interface modified zinc anode as described in claim 1 or 2, characterized in that, The process includes the following steps: dissolving a fluorine compound and a polymer in an organic acid to obtain a coating solution; fully covering the zinc substrate surface with the coating solution and then drying it; causing zinc compounds to be generated in situ on the zinc substrate surface to form an inorganic layer, and the polymer to be deposited on the outermost layer to form an organic layer.

4. The functionally synergistic gradient interface modified zinc anode according to claim 3, characterized in that, The fluorine compound includes one or more of silver fluoride, copper fluoride, tin fluoride, nickel fluoride, or cobalt fluoride; the polymer includes one or more of polyamide, polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, polyacrylic acid, or polyethylene oxide.

5. The method for preparing a functionally synergistic gradient interface modified zinc anode according to claim 3, characterized in that, The organic acid includes one or more of formic acid, trifluoroacetic acid, dichloroacetic acid, or chloroacetic acid.

6. The method for preparing a functionally synergistic gradient interface modified zinc anode according to claim 3, characterized in that, The concentration of the silver compound in the coating solution is 5-10 mmol / L; the concentration of the polymer in the coating solution is 0.05-0.2 g / mL.

7. The method for preparing a functionally synergistic gradient interface modified zinc anode according to claim 3, characterized in that, The drying temperature is 60~80℃, and the time is 8~12h.

8. The application of the functionally synergistic gradient interface modified zinc anode as described in claim 1 or 2 in batteries, capacitors or supercapacitors.

9. A battery prepared using a zinc anode modified with a functional synergistic gradient interface as described in claim 1 or 2, characterized in that, The battery includes a symmetrical battery, a half-cell, or a full-cell battery.

10. The battery according to claim 9, characterized in that, The battery is a zinc-iodine battery, with the positive electrode being an iodine positive electrode or a halogen positive electrode containing polyiodine ions that can be reversibly converted.

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