Composite positive electrode of aqueous zinc organic iodine battery, preparation method of composite positive electrode and aqueous zinc organic iodine battery

Abstract

The invention discloses a composite positive electrode of an aqueous zinc organic iodine battery, a preparation method of the composite positive electrode and the aqueous zinc organic iodine battery, and belongs to the technical field of aqueous zinc ion batteries. The aqueous zinc organic iodine battery composite positive electrode comprises a current collector and an organic iodine dry electrode, and the organic iodine dry electrode is prepared from a phenazine-iodine charge transfer compound, a conductive agent and a binder under a solvent-free condition through a dry rolling technology. The phenazine-iodine charge transfer compound is used as the aqueous zinc organic iodine positive electrode active material, and due to high electronic conductivity and low solubility, the aqueous zinc organic iodine positive electrode active material shows excellent rate capability and cycling stability, also has high discharge voltage and low overpotential, still has good electrochemical performance under high load, and has important application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of aqueous zinc ion batteries, and particularly relates to an aqueous zinc-organic iodine battery composite positive electrode and a preparation method thereof, and an aqueous zinc-organic iodine battery. Background Art

[0002] With the increasing global concern about environmental issues and the growing demand for sustainable energy, it has become crucial to develop energy storage systems with high safety, low cost, long life and environmentally friendly characteristics. As a new energy storage technology, aqueous zinc-ion batteries have attracted widespread attention due to their high theoretical specific capacity, safety and low cost, and have shown great application potential in grid-scale energy storage systems. At present, the research on aqueous soft-pack batteries is still in its infancy. Most aqueous soft-pack batteries have very low cycle life (<100 cycles) and initial discharge capacity (less than 0.1 Ah), which seriously hinders the commercialization of aqueous zinc-ion batteries. One of the challenges faced by aqueous soft-pack zinc-ion batteries is to develop better-performing cathode materials and improve the electrochemical performance of aqueous soft-pack zinc-ion batteries.

[0003] Organic materials hold great potential as cathode materials for aqueous zinc-ion batteries due to their low cost, environmental compatibility, and structural tunability, aligning with current sustainable development goals. Compared to inorganic materials, their use in zinc-ion batteries avoids the structural changes caused by multivalent ion insertion and strong electrostatic repulsion. However, organic materials often suffer from drawbacks such as poor electronic conductivity, poor solubility of redox intermediates, and low utilization of active groups, resulting in poor rate performance and cycling stability, which limits their widespread application in zinc-ion batteries. In particular, imine compounds (such as phenazines), while exhibiting some promising electrochemical performance as aqueous organic cathode materials, still face the aforementioned challenges.

[0004] Current research indicates that the stability of organic materials can be improved through structural modification, the introduction of intermolecular linkers to increase molecular size, or through extended π-conjugated structures. While increasing the size of the molecular skeleton helps improve the material's insolubility, the introduction of inactive groups reduces the material's specific capacity. While extended π-conjugated structures can enhance the material's insolubility and increase electronic conductivity, this extended π structure reduces the redox potential, thereby affecting the battery's discharge voltage and ultimately leading to a decrease in the energy density of the positive electrode material. Therefore, optimizing the discharge voltage of organic materials while maintaining good reaction kinetics has become the key to improving the performance of organic materials in aqueous zinc-ion batteries. Summary of the Invention

[0005] The present invention aims to provide an aqueous zinc-organic iodine battery composite positive electrode, a preparation method thereof, and an aqueous zinc-organic iodine battery. The aqueous zinc-organic iodine battery composite positive electrode has excellent rate performance and cycle stability, as well as a high discharge voltage and low overpotential, and has significant application prospects.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: Provided is an aqueous zinc-organic iodine battery composite positive electrode, comprising a current collector and an organic iodine dry electrode, wherein: The organic iodine dry electrode is prepared by using a phenazine-iodine complex, a conductive agent and a binder through a dry rolling technology under solvent-free conditions.

[0007] The present invention uses a phenazine-iodine complex as the positive electrode active material of an aqueous zinc-organic iodine battery. This material changes the crystal structure of phenazine through the charge transfer interaction between the electron donor (phenazine) and the electron acceptor (iodine), reduces the interlayer spacing between its molecules, thereby enhancing the π-π stacking effect between the molecular layers, significantly improving its electronic conductivity (an increase of 7 orders of magnitude), thereby improving the reaction kinetics and effectively improving the battery's rate performance; at the same time, NH···I - The hydrogen bond structure effectively reduces the solubility of redox intermediates, thereby significantly improving the battery's cycle stability and capacity retention. In addition, the charge transfer interaction in the phenazine-iodine complex is an intermolecular force. Compared with the π-conjugated structure extended by covalent bonds, it does not have a negative impact on the battery's discharge voltage. Therefore, the battery has a higher discharge voltage while improving rate performance and cycle stability.

[0008] According to the above scheme, the structural formula of the phenazine-iodine complex is:

[0009] According to the above scheme, the phenazine-iodine complex is prepared by dropwise adding an iodine ether solution to a phenazine ether solution, wherein the mass ratio of iodine to phenazine is (0.5-1.5):1.

[0010] According to the above scheme, the organic iodine dry electrode is prepared by mixing and grinding a phenazine-iodine complex and a conductive agent, adding a binder, and then fibrillating the binder under the action of shear force to bond the powder into a block, and then rolling to obtain an organic iodine dry electrode.

[0011] Preferably, the grinding time is ≥30 min.

[0012] Preferably, the rolling time is ≥15 min.

[0013] According to the above scheme, the mass ratio of the phenazine-iodine complex, the conductive agent and the binder is (30~80):(15~69):(1~5).

[0014] According to the above solution, the conductive agent is selected from one or a combination of acetylene black (AB), Super P, Ketjen black (KB), activated carbon, single-walled carbon nanotubes and multi-walled carbon nanotubes.

[0015] According to the above solution, the binder is one or a combination of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR).

[0016] According to the above solution, the current collector is a titanium mesh or a stainless steel mesh, and its size should be larger than that of the dry-process positive electrode so that the full dry-process positive electrode membrane can be better attached to the current collector.

[0017] According to the above scheme, the loading amount of the positive electrode active material in the organic iodine dry electrode is 2.0~60 mg cm -2 .

[0018] Provided is a method for preparing the aqueous zinc-organic iodine composite positive electrode, comprising the following steps: rolling and compounding an organic iodine dry-process electrode on a current collector to obtain an aqueous zinc-organic iodine composite positive electrode.

[0019] Provided is an aqueous zinc-organic iodine battery, comprising the aqueous zinc-organic iodine composite positive electrode.

[0020] According to the above solution, the battery further includes a negative electrode, an electrolyte and a separator.

[0021] Preferably, the negative electrode is a zinc sheet.

[0022] Preferably, the electrolyte is one or more of zinc sulfate solution and zinc trifluoromethanesulfonate solution.

[0023] Preferably, the concentration of the electrolyte is 2-3 mol L -1 .

[0024] Preferably, the diaphragm is one or more of glass fiber membrane GF / A and glass fiber membrane GF / D.

[0025] According to the above solution, the aqueous zinc-organic iodine battery is a button-type or soft-pack battery.

[0026] According to the above scheme, the aqueous zinc-organic iodine battery is prepared and allowed to stand for 3-12 hours before use.

[0027] The beneficial effects of the present invention are as follows: 1. The present invention provides a composite positive electrode for an aqueous zinc-organic iodine battery, comprising a current collector and an organic iodine dry electrode. A phenazine-iodine complex is used as the positive electrode active material. Charge transfer interactions and interlayer π-π stacking effects significantly enhance the electronic conductivity, optimize reaction kinetics, and effectively reduce the solubility of redox intermediates. The composite cathode exhibits excellent rate capability and cycle stability, high discharge voltage, and low overpotential. When used in aqueous zinc-organic iodine batteries, the composite cathode can achieve an initial discharge capacity of up to 1.1 ampere-hours for zinc-organic iodine soft-pack batteries, and maintain a capacity retention rate of 70% after 700 cycles, demonstrating excellent cycle stability and promising prospects for practical application.

[0028] 2. Furthermore, the present invention adopts a dry method to prepare the positive electrode sheet, which is conducive to achieving a high loading of the positive electrode active material phenazine-iodine complex. The extremely high electronic conductivity of the phenazine-iodine complex combined with the high ionic conductivity of the aqueous electrolyte enables the resulting zinc-organic iodine battery to still have good electrochemical performance even under high positive electrode loading.

[0029] 3. The present invention provides a method for preparing a composite positive electrode for an aqueous zinc-organic iodine battery, which has a simple preparation process and is conducive to industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used for explaining the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0031] Figure 1 This is a flow chart for preparing the electrode sheet of the zinc-organic iodine battery in an embodiment of the present invention.

[0032] Figure 2 Schematic diagram of the preparation of zinc-organic iodine soft-pack batteries in Example 1 of the present invention.

[0033] Figure 3 The Zn / / PNZ-I2 soft pack battery with an initial discharge capacity of 1.1 Ah in Example 1 was discharged at 0.25 A g -1 Cycling performance diagram at different current densities.

[0034] Figure 4 This is a price comparison chart of the organic iodine active material PNZ-I2 in Example 1 and common positive electrode materials.

[0035] Figure 5 The UV-visible spectra of the discharge products of the organic active material PNZ-I2 selected in Example 1 and the common n-type positive electrode material PNZ in 2M ZnSO4 aqueous solution.

[0036] Figure 6This is the XRD characterization diagram of the organic active material PNZ-I2 after recovery using dichloromethane in Example 1.

[0037] Figure 7 The button cells assembled with the PNZ-I2 obtained in Example 1 and the PNZ positive electrode materials obtained in Comparative Example 1 were heated at 3.0Ag. -1 Comparison of long cycle performance at different current densities.

[0038] Figure 8 This is a comparison chart of the rate performance of button batteries assembled with the PNZ-I2 positive electrode materials obtained in Example 1 and the PNZ positive electrode materials obtained in Comparative Example 1 at different current densities.

[0039] Figure 9 The button cell assembled with the PNZ-I2 cathode material obtained in Example 1 was heated to 0.2 A g -1 Charge and discharge curves at different current densities.

[0040] Figure 10 The button cell assembled with the PNZ-I2 cathode material obtained in Example 2 was 60.0 mg cm -2 Long-cycle performance diagram at different active material loading levels.

[0041] Figure 11 The button cell assembled with the PNZ-I2 cathode material obtained in Example 3 was 21.0 mg cm -2 Long-cycle performance diagram at different active material loading levels. DETAILED DESCRIPTION

[0042] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0043] Example 1 This embodiment provides a composite positive electrode for an aqueous zinc-organic iodine battery, such as Figure 1 As shown, the following steps are included: 1) The organic iodine active material phenazine-iodine complex PNZ-I2 and Ketjen black were preliminarily mixed in a mass ratio of 1:1, and the resulting mixture was thoroughly ground in a small mortar for 30 minutes to mix uniformly to obtain a mixed powder; the mixed powder and the binder polytetrafluoroethylene were then mixed in a mortar in a mass ratio of 95:5. Under the action of shear force, the polytetrafluoroethylene binder fibrillated and bonded the mixed powder into an electrode blank, which was repeatedly rolled in a hot roller device for 15 minutes. The electrode blank was cut into square electrodes with a side length of 9 cm to obtain an organic iodine dry-process electrode.

[0044] The preparation of the phenazine-iodine complex PNZ-I2 comprises the following steps: First, phenazine was dispersed in diethyl ether and iodine was dissolved in the same solvent, yielding 100 g / L phenazine and 100 g / L iodine solutions, respectively. Under constant stirring at room temperature, the iodine solution was added dropwise to the phenazine solution. An orange-yellow precipitate immediately formed, yielding the PNZ-I2 complex (mass ratio of phenazine to iodine = 1:1). The specific reaction equation is shown below:

[0045] 2) The organic iodine dry electrode was then rolled onto a titanium (Ti) mesh to form a composite positive electrode for a zinc-organic iodine battery. The resulting electrode had an organic iodine active material loading of 10 mg cm -2 about.

[0046] Battery assembly: Figure 2 As shown in the figure, the zinc-organic iodine battery is assembled in sequence according to the composite positive electrode, separator, electrolyte, negative electrode and current collector Ti. The separator is a glass fiber membrane GF / D, and the electrolyte used is 2 mol L -1 A zinc sulfate aqueous solution was added to fully soak the positive electrode sheet. The negative electrode was a square zinc sheet with a side length of 9.5 cm (a circular zinc sheet with a diameter of 14 mm for button cells). After assembling the button cells and soft-pack batteries, their electrochemical performance was tested.

[0047] Electrochemical performance testing: All battery assembly was completed in air at room temperature. Constant current charge-discharge testing and long cycle testing of soft-pack batteries were achieved using the CT2001A LAND, with a test voltage window of 0.3-1.6 V.

[0048] Example 2 The specific steps are the same as those in Example 1, except that the active material loading is 60.0 mg cm -2 , assembled into button batteries for long cycle testing.

[0049] Example 3 The specific steps are the same as those in Example 1, except that the active material loading is 21.0 mg cm -2 , assembled into button batteries for long cycle testing.

[0050] Comparative Example 1 The specific steps are the same as those in Example 1, except that phenazine PNZ is selected as the organic active material, and button cells are assembled for long cycle testing.

[0051] like Figure 3As shown, the ampere-hour-level Zn / / PNZ-I2 soft-pack battery obtained in Example 1 shows an initial discharge capacity of up to 1.1 ampere-hour, and maintains 80% of the capacity after 450 cycles, and even after 700 cycles, the capacity retention rate still reaches 70%. The present invention has realized the ampere-hour-level aqueous zinc-organic soft-pack battery for the first time, showing potential large-scale application prospects in energy storage fields such as grid-side energy storage and power generation-side energy storage.

[0052] like Figure 4 As shown in the figure, the cost of PNZ-I2 positive electrode material is compared with lithium iron phosphate (LiFePO4), lithium cobalt nickel manganese oxide (NCM), vanadium pentoxide (V2O5), polyaniline (PANI) and hexaazanaphthalene (HATN). The results show that the cost of PNZ-I2 positive electrode material is only 1 / 20 of lithium iron phosphate (LiFePO4), 1 / 85 of lithium cobalt nickel manganese oxide, and 1 / 90 of hexaazanaphthalene. Therefore, the present invention can effectively reduce the production cost of the battery while improving the performance.

[0053] like Figure 5 As shown, UV-visible spectroscopy proves that N–H···I - The interaction reduces the binding between the reduction product of phenazine (2H-PNZ) and water molecules in the electrolyte, thereby inhibiting the dissolution of 2H-PNZ in the aqueous electrolyte and enhancing the cycling stability.

[0054] like Figure 6 As shown, the X-ray diffraction analysis results prove the successful recycling of PNZ-I2 positive electrode material, and it can be reused after recycling. Its recyclability is closely related to renewable energy and transformative energy technology, which is conducive to industrial development.

[0055] like Figure 7 As shown, at 3 A g -1 The following tests compared the long-term cycling stability of the button cells obtained from Example 1 (PNZ-I2) and Comparative Example 1 (PNZ). After 4500 cycles, the PNZ-I2 cathode retained 92% of its initial capacity. In contrast, the PNZ cathode not only required additional activation time but also exhibited poor stability, failing after less than 3000 cycles, retaining only 69% of its initial capacity.

[0056] like Figure 8 As shown in the figure, the rate performance of the button cells of Example 1 (PNZ-I2) and Comparative Example 1 (PNZ) was tested at different current densities. Thanks to the excellent electronic conductivity and stability, the Zn / / PNZ-I2 battery has a high rate performance in the range of 0.5 to 10.0 A g -1 It exhibits excellent rate performance in a wide current density range.

[0057] like Figure 9As shown in the charge and discharge curve, it can be seen that at 0.2 A g -1 Under this condition, the average discharge voltage is 0.89V.

[0058] like Figure 10 As shown in the figure, the coin cell assembled with PNZ-I2 cathode material in the obtained coin cell has a mass fraction of 60.0 mg cm -2 Under the highest active material loading, the capacity retention rate is 75% after 100 cycles.

[0059] like Figure 11 As shown in the figure, the PNZ-I2 cathode material in the button cell is assembled at 21.0 mg cm -2 Under the active material loading, the capacity retention rate is 80% after 2000 stable cycles.

[0060] The above analysis demonstrates that the zinc-organic iodine battery cathode material provided by this invention offers advantages such as high electronic conductivity, fast reaction kinetics, and low solubility, overcoming the problems of slow kinetics and low capacity retention of organic cathodes in aqueous systems. Combined with a dry-process electrode sheet preparation method, the organic iodine electrode exhibits excellent cycling stability in ampere-hour-class soft-pack batteries assembled at high active material loadings. The mild synthesis and recyclability of PNZ-I2 are closely related to renewable energy and transformative energy technologies, facilitating their industrialization. This invention provides new insights into the design and application of organic electrodes in high-performance batteries.

[0061] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A composite positive electrode for an aqueous zinc-organic iodine battery, characterized in that: It includes a current collector and an organic iodine dry electrode, wherein: The organic iodine dry electrode is prepared by using a phenazine-iodine complex, a conductive agent and a binder through a dry rolling technology under solvent-free conditions.

2. The aqueous zinc-organic iodine battery composite positive electrode according to claim 1, characterized in that The structural formula of the phenazine-iodine complex is: .

3. The aqueous zinc-organic iodine battery composite positive electrode according to claim 1, characterized in that The phenazine-iodine complex is prepared by dropwise adding an iodine ether solution into a phenazine ether solution.

4. The aqueous zinc-organic iodine battery composite positive electrode according to claim 1, characterized in that The organic iodine dry electrode is prepared by mixing and grinding a phenazine-iodine complex and a conductive agent, adding a binder, and then fibrillating the binder under the action of shear force to bond the powder into a block, and then rolling to obtain the organic iodine dry electrode.

5. The aqueous zinc-organic iodine battery composite positive electrode according to claim 1, characterized in that: The mass ratio of the phenazine-iodine complex, the conductive agent, and the binder is (30-80):(15-69):(1-5).

6. The aqueous zinc-organic iodine battery composite positive electrode according to claim 1, characterized in that The conductive agent is selected from one or a combination of acetylene black, Super P, Ketjen black, activated carbon, single-walled carbon nanotubes and multi-walled carbon nanotubes; the binder is one or a combination of polytetrafluoroethylene, polyvinylidene fluoride, carboxymethyl cellulose and styrene-butadiene rubber.

7. The aqueous zinc-organic iodine battery composite positive electrode according to claim 1, characterized in that: The current collector is a titanium mesh or a stainless steel mesh.

8. The aqueous zinc-organic iodine battery composite positive electrode according to claim 1, characterized in that: In the organic iodine dry electrode, the loading amount of the positive electrode active material is 2.0~60 mg cm -2 .

9. A method for preparing an aqueous zinc-organic iodine composite positive electrode according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: rolling and compounding an organic iodine dry-process electrode on a current collector to obtain an aqueous zinc-organic iodine composite positive electrode.

10. An aqueous zinc-organic iodine battery, characterized in that: It includes the above-mentioned aqueous zinc-organic iodine composite positive electrode.

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