Difunctional and highly reversible zinc negative electrode and preparation method and application thereof

Abstract

The invention relates to a difunctional and highly reversible zinc negative electrode and a preparation method and application thereof, and belongs to the technical field of zinc metal negative electrode surface modification.The preparation method comprises the following steps that S1, oxyiodide is deposited on metal oxide, and an oxyiodide / metal oxide composite material is prepared; s2, uniformly mixing a fluorine-containing polymer solution with the oxyiodide / metal oxide composite material obtained in the step S1, performing ultrasonic treatment, and stirring until a uniform composite solution is formed; and S3, coating a zinc negative electrode plate substrate with the composite solution obtained in S2, and drying to obtain the bifunctional and highly reversible zinc negative electrode. Compared with the prior art, a simple coating process is adopted, the performance of the zinc metal is improved through in-situ construction of the three-dimensional porous hydrophobic-zinc-loving conductive modified layer on the surface of the zinc metal, the zinc-loving conductive layer is ingeniously combined with surface coating, and the hydrophobic-zinc-loving conductive three-dimensional porous zinc negative electrode is constructed in situ.

Description

Technical Field

[0001] The present invention relates to the technical field of surface modification of zinc metal negative electrodes, and in particular to a dual-functional, highly reversible zinc negative electrode and a preparation method and application thereof. Background Art

[0002] With the increasing consumption and depletion of traditional non-renewable energy sources, rechargeable batteries with high safety and high power density are attracting more and more attention. Traditional lithium-ion batteries are widely used in various electronic devices due to their advantages such as long cycle life and high operating voltage. However, a series of problems such as the toxicity and flammability of organic electrolytes and the scarcity of lithium resources have restricted the rapid development of lithium-ion batteries. Rechargeable batteries with aqueous solutions as electrolytes (such as sodium / potassium / aluminum ion batteries) have attracted widespread attention due to their advantages such as high safety and low cost. Among them, aqueous zinc-ion batteries (AZIBs) are considered to be the most promising energy storage devices due to their abundant zinc resources and environmental friendliness.

[0003] AZIBs usually use two-dimensional (2D) zinc foil as the negative electrode. However, 2D zinc foil has problems such as uncontrollable dendrite growth, hydrogen evolution, corrosion and passivation during the cycle process, resulting in low coulombic efficiency and short cycle life of the battery, which greatly hinders the practical application of AZIBs. In recent years, researchers have been committed to improving the stability of zinc electrodes through various approaches, such as optimizing electrode structure design, adding electrode / electrolyte additives and other technical means. Among these methods, the electrode additive strategy has attracted widespread attention due to its high efficiency and easy operation. However, most of the current applications of additives still use the traditional mechanical mixing method, that is, simply mixing the zinc oxide active material with the additive. This method has significant defects: on the one hand, it is difficult to ensure sufficient contact between the active material and the additive; on the other hand, during the battery cycle, the active material and the additive are prone to aggregation, which causes deformation of the electrode structure.

[0004] For example, a water-based zinc-iodine battery without an ion exchange membrane and its preparation method disclosed in Chinese patent (202310998071.4) can effectively alleviate problems such as dendrite growth and hydrogen evolution of the zinc negative electrode during charging and discharging. However, in this system, the compositional stability of the selenium (Se) film is insufficient. Under certain conditions, the formed selenium (Se) film is mainly composed of elemental Se, and the ratio of selenium (Se) to zinc (Zn) elements fluctuates greatly, which has an adverse effect on the performance of the membrane and the stability of the battery.

[0005] In addition, the aqueous zinc battery modification method disclosed in Chinese invention patent No. 202410580410.1 has the problem of insufficient uniformity of the modified layer. Specifically, in the process of immersing in a copper sulfate solution to form a copper-zinc alloy modified layer, no specific technical means for ensuring the uniformity of the modified layer are clearly mentioned. If the modified layer is unevenly distributed, it may lead to local performance differences, which will adversely affect the overall performance of the battery. Summary of the Invention

[0006] In view of the problems that the existing technology cannot effectively achieve uniform deposition and dissolution of zinc ions, and it is difficult to effectively inhibit side reactions such as dendrite growth, resulting in unsatisfactory cycle stability of aqueous zinc ion batteries in practical applications, the present invention provides a dual-functional, highly reversible zinc anode and its preparation method and application.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] One of the purposes of the present invention is to provide a method for preparing a dual-functional, highly reversible zinc negative electrode, comprising the following steps:

[0009] S1. uniformly depositing iodine oxide on the metal oxide to prepare an iodine oxide / metal oxide composite material;

[0010] S2, uniformly mixing the fluoropolymer solution and the iodine oxide / metal oxide composite material obtained in S1, and stirring after ultrasonication until a uniform composite solution is formed;

[0011] S3. The composite solution obtained in S2 is coated on a zinc negative electrode substrate, and after drying, a bifunctional, highly reversible zinc negative electrode is obtained.

[0012] Furthermore, in S1:

[0013] The iodine oxide includes one or more of arsenic iodide, bismuth iodide, tin iodide, selenium iodide, vanadium iodide or manganese iodide;

[0014] The metal oxide includes one or more of copper oxide, barium oxide, zinc oxide, indium oxide, chromium oxide or iron oxide;

[0015] The mass ratio of the iodine oxide to the metal oxide is 3:7 to 7:3.

[0016] Furthermore, in S1: the iodine oxide is deposited on the metal oxide by a hydrothermal method.

[0017] Furthermore, in S2: the fluoropolymer solution is obtained by dissolving the fluoropolymer solution in a mixed solvent, the mixed solvent consisting of component A and component B in a mass ratio of (9:1):(1:9), the component A includes any one of toluene, N,N-dimethylformamide, tetrahydrofuran, and N-methylpyrrolidone, and the component B includes any one of tetrahydrofuran, acetone, dichloromethane, N,N-dimethylformamide, and N-methylpyrrolidone.

[0018] Furthermore, the preparation method of the composite solution is: after grinding the fluorine-containing polymer powder and iodine oxide / metal oxide in a mortar evenly, gradually adding them into a mixed solvent, ultrasonicating for 20 minutes to 60 minutes, and then using an electromagnetic stirrer to stir for 1 hour to 12 hours in a constant temperature water bath at 60°C to obtain a composite solution.

[0019] Furthermore, in S2:

[0020] The mass concentration of the fluoropolymer in the fluoropolymer solution is 5% to 20%;

[0021] The fluorine-containing polymer is PVDF or its copolymer with a molecular weight of 300,000 to 1,000,000, including one of polyvinylidene fluoride, polyvinylidene fluoride-trifluoroethylene, polyvinylidene fluoride-fluorinated chloroethylene or polyvinylidene fluoride-fluorinated polymer;

[0022] The mass ratio of the fluorine-containing polymer to the iodine oxide / metal oxide composite material is 9:1 to 1:9.

[0023] Furthermore, in S3, the coating operation is to coat the composite solution on the zinc negative electrode substrate by a coating machine, and the coating parameters of the coating machine are set to: coating times 1 to 3 times, coating speed 1000 r / min to 9000 r / min, and coating time 10s to 200s.

[0024] Furthermore, in S3, the drying operation is performed by placing the zinc negative electrode substrate coated with the composite solution in a dry environment with a humidity of 30% to 35%, or further drying it in a low-temperature oven at 45° C. to 60° C. to remove excess solvent.

[0025] A second object of the present invention is to provide a bifunctional, highly reversible zinc negative electrode, which is prepared using the preparation method described above.

[0026] A third object of the present invention is to use a bifunctional, highly reversible zinc negative electrode as described above in electrochemical energy storage, new energy vehicles or fuel cells.

[0027] The present invention adopts a simple coating process to improve its performance by in-situ constructing a three-dimensional porous hydrophobic-zincophilic conductive modified layer on the zinc metal surface, cleverly combining the zincophilic conductive layer with a hydrophobic polymer, and in-situ constructing a hydrophobic-zincophilic conductive three-dimensional porous zinc negative electrode. Among them, the hydrophobic fluoropolymer can increase the interfacial free energy between the Zn substrate and the electrolyte, effectively isolate the direct contact between the zinc negative electrode and the water molecules in the electrolyte and provide mechanical support. Iodine oxide regulates the zinc ion deposition behavior, and metal oxide optimizes the SEI (Solid Electrolyte Interphase, solid electrolyte interface) film structure and increases zincophilic sites. The synergy of the three can not only effectively inhibit dendrite growth and reduce side reactions, but also improve interface stability and ion conduction efficiency, and has outstanding performance in high rate performance and long cycle life, making up for the defects of single fluoropolymer or iodine oxide / metal oxide modified negative electrode single function and insufficient synergy, and providing a better solution for the practical application of aqueous zinc ion batteries.

[0028] Compared to existing technologies, the present invention significantly improves battery cycle stability, meaning that the battery maintains stable and consistent performance during repeated charge and discharge cycles. This improvement extends the battery's service life, offering significant value in practical applications. This extended service life not only reduces the need for frequent battery replacements but also reduces maintenance costs, improving device reliability and user experience. This invention has significant practical value in improving battery performance and economic efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the SEM image of the PVDF-BiOI / ZnO modified zinc negative electrode of the present invention.

[0030] Figure 2 Corrosion polarization curves of bare Zn and PVDF-BiOI / ZnO modified Zn anode. DETAILED DESCRIPTION

[0031] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0032] All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Where specific conditions are not specified, conventional conditions or those recommended by the manufacturer shall be followed. Where the manufacturer of the reagents or instruments used is not specified, they are all commercially available conventional products.

[0033] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to form one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed in the present invention.

[0034] The molecular weight of PVDF or its copolymer in the following examples and comparative examples is 700,000.

[0035] Example 1

[0036] The zinc sheet was cut into appropriate size and polished with metallographic sandpaper to remove the surface passivation layer, ultrasonically cleaned for 20 minutes, then cleaned with ethanol, and dried in a vacuum drying oven at 60°C for 2 hours to obtain the zinc negative electrode sheet substrate;

[0037] 3.32 g of KI was fully dissolved in 50 ml of deionized water, and the pH of the solution was adjusted to 1.7 with HNO3. 0.97014 g of Bi(NO3)3·5H2O was added to the solution and stirred for 1 h until the reaction was complete. 7 g of ZnO powder was added and stirred continuously for 5 h until the mixture was uniformly mixed. The solution was filtered and washed thoroughly with deionized water to remove the residual solution. The BiOI film deposited on the ZnO powder was separated and obtained, and the BiOI / ZnO powder was obtained after vacuum drying for 12 h.

[0038] 0.4 g BiOI / ZnO composite material and 0.6 g PVDF powder were dissolved in 5 ml of a solution of NMP and DMF in a ratio of 4:6. After ultrasonication for 30 min, stirring was continued with an electromagnetic stirrer in a constant temperature water bath at 60 °C for 12 h until fully dissolved to obtain a PVDF-BiOI / ZnO composite solution.

[0039] The PVDF-BiOI / ZnO composite solution was evenly coated on the zinc negative electrode substrate by a coating machine (the parameters of the coating machine were: coating times 2 times, first coating speed 3000r / min, coating time 100s, second coating speed 6000r / min, coating time 20s), and dried in a vacuum drying oven at 60°C for 12h to obtain a modified negative electrode ( Figure 1 ). At different current densities, symmetrical cells containing PVDF-BiOI / ZnO electrodes show lower voltage hysteresis than bare zinc cells. PVDF-BiOI / ZnO coating can effectively reduce interfacial resistance, uniform zinc ion deposition, and improve stripping / plating stability and dendrite growth resistance at extremely high current densities. Potential polarization tests were used to quantitatively evaluate interface stability. Figure 2It can be seen that the corrosion current density of the PVDF-BiOI / ZnO modified negative electrode is reduced by 59% (0.46 mA cm -2 vs 1.12mA cm -2 ), indicating that the PVDF-BiOI / ZnO interface phase effectively inhibits the corrosion trend and speed. Among them, the hydrophobic properties of polyvinylidene fluoride (PVDF) form a physical barrier on the electrode surface, effectively blocking the corrosion of free water molecules in the electrolyte on the zinc negative electrode, and significantly reducing the activity of side reactions such as hydrogen evolution and corrosion. At the same time, the BiOI / ZnO composite structure synergistically optimizes the zinc deposition behavior through dual functions: on the one hand, the zinc-philic properties of BiOI / ZnO promote uniform nucleation by reducing the zinc nucleation barrier; on the other hand, the three-dimensional conductive network constructed by BiOI / ZnO guides the directional migration of zinc ions, and the zinc ion flux tends to be homogenized through the spatial charge redistribution effect. This synergistic effect of hydrophobic protection and zinc-philic ion-conducting structure significantly improves the kinetics and stability of the zinc deposition / stripping process.

[0040] Example 2

[0041] The zinc sheet was cut into appropriate size and polished with metallographic sandpaper to remove the surface passivation layer, ultrasonically cleaned for 20 minutes, then cleaned with ethanol, and dried in a vacuum drying oven at 60°C for 2 hours to obtain the zinc negative electrode sheet substrate;

[0042] 3.32 g of KI was fully dissolved in 50 ml of deionized water, and the pH of the solution was adjusted to 1.7 with HNO3. 0.97014 g of Bi(NO3)3·5H2O was added to the solution, and the mixture was stirred for 1 hour until the reaction was complete. 7 g of ZnO powder was added and stirred continuously for 5 hours until the mixture was uniformly mixed. The solution was filtered and washed with deionized water to remove the residual solution, and a BiOI film deposited on the ZnO powder was separated and obtained. The BiOI / ZnO composite powder was obtained after vacuum drying for 12 hours.

[0043] 0.3 g BiOI / ZnO composite material and 0.7 g PVDF-CTFE powder were dissolved in 5 ml THF solution, and then ultrasonicated for 40 min and stirred continuously for 12 h in a constant temperature water bath at 60 °C using an electromagnetic stirrer until fully dissolved to obtain a PVDF-CTFE-BiOI / ZnO composite solution;

[0044] The PVDF-CTFE-BiOI / ZnO composite solution was evenly coated onto a zinc anode substrate using a spreader (spreader parameters: 1 coat, 6000 rpm, 120 s). The solution was then dried in a vacuum oven at 60°C for 12 hours to produce a modified PVDF-CTFE-BiOI / ZnO anode. The treated zinc surface changed from metallic silver to white. The modified PVDF-CTFE-BiOI / ZnO anode surface was able to withstand mechanical stresses such as curling, folding, and tape tearing, demonstrating long-lasting stability.

[0045] Example 3

[0046] The zinc sheet was cut into appropriate size and polished with metallographic sandpaper to remove the surface passivation layer, ultrasonically cleaned for 20 minutes, then cleaned with ethanol, and dried in a vacuum drying oven at 60°C for 2 hours to obtain the zinc negative electrode sheet substrate;

[0047] 3.32 g of KI was fully dissolved in 50 ml of deionized water, and the pH of the solution was adjusted to 1.7 with HNO3. 0.97014 g of Bi(NO3)3·5H2O was added to the solution and stirred for 1 h until the reaction was complete. 7 g of ZnO powder was added and stirred continuously for 5 h until the mixture was uniformly mixed. The solution was filtered and washed thoroughly with deionized water to remove the residual solution. The BiOI film deposited on the ZnO powder was separated and obtained, and the BiOI / ZnO powder was obtained after vacuum drying for 12 h.

[0048] 0.45 g BiOI / ZnO composite material and 1.05 g PVDF-PE powder were dissolved in 5 ml DMF solution. After ultrasonication for 50 min, stirring was continued for 12 h in a 60 °C constant temperature water bath with an electromagnetic stirrer until fully dissolved to obtain a PVDF-PE-BiOI / ZnO composite solution.

[0049] The PVDF-PE-BiOI / ZnO composite solution was evenly coated onto a zinc anode substrate using a slurry coater (slurry coater parameters: three coats, first coat at 2500 r / min, coating time 60 s, second coat at 5000 r / min, coating time 40 s, and third coat at 8000 r / min, coating time 20 s). The modified PVDF-PE-BiOI / ZnO anode was obtained by drying in a vacuum oven at 60°C for 12 h. In situ cells were assembled and tested at 10 mA cm⁻². Dendrite growth was observed using in situ optical electron microscopy. Compared to the pure zinc anode, the PVDF-PE-BiOI / ZnO anode maintained a relatively flat surface during long-term charge and discharge processes. No bubbles were detected within the same deposition time, indicating that the PVDF-PE-BiOI / ZnO anode significantly inhibited zinc dendrites and the HER.

[0050] Example 4

[0051] The zinc sheet was cut into appropriate size and polished with metallographic sandpaper to remove the surface passivation layer, ultrasonically cleaned for 20 minutes, then cleaned with ethanol, and dried in a vacuum drying oven at 60°C for 2 hours to obtain the zinc negative electrode sheet substrate;

[0052] 3.32 g of KI was fully dissolved in 50 ml of deionized water, and the pH of the solution was adjusted to 1.7 with HNO3. 0.97014 g of Bi(NO3)3·5H2O was added to the solution and stirred for 1 h until the reaction was complete. 7 g of ZnO powder was added and stirred continuously for 5 h until the mixture was uniformly mixed. The solution was filtered and washed thoroughly with deionized water to remove the residual solution. The BiOI film deposited on the ZnO powder was separated and obtained, and the BiOI / ZnO powder was obtained after vacuum drying for 12 h.

[0053] 0.4 g BiOI / ZnO composite material and 0.5 g PVDF-TREF powder were dissolved in 5 ml of a solution of DMF and THF in a ratio of 4:6. After ultrasonication for 30 min, stirring was continued with an electromagnetic stirrer in a constant temperature water bath at 60 °C for 12 h until fully dissolved to obtain a PVDF-TREF-BiOI / ZnO composite solution.

[0054] The PVDF-TREF-BiOI / ZnO composite solution was evenly coated on the treated zinc foil using a coater (coating machine parameters were: coating times 1, coating speed 5000 r / min, coating time 120 s) and dried in a vacuum drying oven at 60°C for 12 h to obtain a PVDF-TREF-BiOI / ZnO modified negative electrode with a maximum contact angle of 116.86°.

[0055] Comparative Example 1

[0056] This comparative example utilizes a method essentially identical to Example 1, except that the coating solution used to modify the zinc anode contains only PVDF, resulting in the PVDF-modified anode. Compared to the PVDF-BiOI / ZnO composite-modified zinc anode, the PVDF-only modified zinc anode, while capable of maintaining its structure through hydrophobicity and mechanical strength, lacks control over zinc ion deposition, preventing dendrite growth. Furthermore, its low ionic conductivity affects rate performance.

[0057] Comparative Example 2

[0058] This comparative example employed essentially the same method as Example 1, except that the coating solution used to modify the zinc anode contained only BiOI / ZnO, resulting in a BiOI / ZnO-modified anode. Compared to the PVDF-BiOI / ZnO composite-modified zinc anode, the BiOI / ZnO-only modified zinc anode, while capable of directing zinc ion deposition, exhibited poor mechanical strength and was easily dissolved in the electrolyte.

[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other manner. Any person skilled in the art may utilize the above-disclosed technical content to modify or modify the present invention into equivalent embodiments. However, any simple modifications, equivalent variations, and modifications to the above embodiments that do not depart from the technical content of the present invention and are based on the technical essence of the present invention remain within the scope of protection of the present invention.

Claims

1. A method for preparing a dual-functional, highly reversible zinc negative electrode, characterized in that: The steps include: S1, depositing iodine oxide on the metal oxide to prepare an iodine oxide / metal oxide composite material; S2, uniformly mixing the fluoropolymer solution and the iodine oxide / metal oxide composite material obtained in S1, and stirring after ultrasonication until a uniform composite solution is formed; S3. The composite solution obtained in S2 is coated on a zinc negative electrode substrate, and after drying, a bifunctional, highly reversible zinc negative electrode is obtained.

2. The method for preparing a bifunctional, highly reversible zinc negative electrode according to claim 1, wherein: In S1: The iodine oxide includes one or more of arsenic iodide, bismuth iodide, tin iodide, selenium iodide, vanadium iodide or manganese iodide; The metal oxide includes one or more of copper oxide, barium oxide, zinc oxide, indium oxide, chromium oxide or iron oxide; The mass ratio of the iodine oxide to the metal oxide is 3:7 to 7:

3.

3. The method for preparing a bifunctional, highly reversible zinc negative electrode according to claim 1, wherein: In S1: the iodine oxide is deposited on the metal oxide by a hydrothermal method.

4. The method for preparing a bifunctional, highly reversible zinc negative electrode according to claim 1, wherein: In S2: the fluoropolymer solution is obtained by dissolving the fluoropolymer solution in a mixed solvent, the mixed solvent consisting of component A and component B in a mass ratio of (9:1):(1:9), the component A includes any one of toluene, N,N-dimethylformamide, tetrahydrofuran, and N-methylpyrrolidone, and the component B includes any one of tetrahydrofuran, acetone, dichloromethane, N,N-dimethylformamide, and N-methylpyrrolidone.

5. The method for preparing a bifunctional, highly reversible zinc negative electrode according to claim 4, characterized in that: The composite solution is prepared by grinding fluorine-containing polymer powder and iodine oxide / metal oxide uniformly in a mortar, gradually adding the powder to a mixed solvent, ultrasonicating for 20 to 60 minutes, and then stirring for 1 to 12 hours in a constant temperature water bath using an electromagnetic stirrer to obtain a composite solution.

6. The method for preparing a bifunctional, highly reversible zinc negative electrode according to claim 1, characterized in that: In S2: The mass concentration of the fluoropolymer in the fluoropolymer solution is 5% to 20%; The fluorine-containing polymer is PVDF or its copolymer with a molecular weight of 300,000 to 1,000,000, including one of polyvinylidene fluoride, polyvinylidene fluoride-trifluoroethylene, polyvinylidene fluoride-fluorinated chloroethylene or polyvinylidene fluoride-fluorinated polymer; The mass ratio of the fluorine-containing polymer to the iodine oxide / metal oxide composite material is 9:1 to 1:

9.

7. The method for preparing a bifunctional, highly reversible zinc negative electrode according to claim 1, characterized in that: In S3, the coating operation is to coat the composite solution on the zinc negative electrode substrate by a coating machine, and the coating parameters of the coating machine are set to: coating times 1 to 3 times, coating speed 1000 r / min to 9000 r / min, and coating time 10s to 200s.

8. The method for preparing a bifunctional, highly reversible zinc negative electrode according to claim 1, characterized in that: In S3, the drying operation is to place the zinc negative electrode substrate coated with the composite solution in a dry environment with a humidity of 30% to 35%, or further dry it in a low-temperature oven at 45° C. to 60° C. to remove excess solvent.

9. A dual-functional, highly reversible zinc negative electrode, characterized in that: The invention discloses a novel cellulose acetate copolymer prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the bifunctional, highly reversible zinc anode according to claim 9 in electrochemical energy storage, new energy vehicles or fuel cells.

Images