An anode material for aqueous zinc-iodine batteries based on amphiphilic molecules, a preparation method thereof and a battery

Abstract

The application discloses a kind of based on amphiphilic molecule water-based zinc-iodine battery positive electrode material and its preparation method and battery, belong to novel electrochemical cell and new energy battery field.The application uses oleylamine amphiphilic molecule and conductive agent mixture as positive electrode iodine host material, and obtains film electrode by the self-spreading behavior of mixture in water, realizes the preparation of zinc-iodine battery positive electrode in extremely short time.The amphiphilic molecule used in the positive electrode, the long-chain hydrophobic tail portion thereof can prevent the film electrode from being dissolved in aqueous electrolyte;And the amine group functional group contained in the hydrophilic head portion can quickly capture and limit the dissolution and diffusion of polyiodide during the charging and discharging process of the battery, thereby avoiding problems such as severe capacity fading and rapid self-discharge of the battery.Therefore, the application greatly simplifies the preparation procedure and process of electrode material, also effectively improves the electrochemical performance and cycle life of zinc-iodine battery, realizes more than 2000 times of charging and discharging cycle.

Description

Technical Field

[0001] This invention belongs to the field of novel electrochemical batteries and new energy batteries, specifically relating to an aqueous zinc-iodine battery cathode material based on amphiphilic molecules, its preparation method, and the battery. Background Technology

[0002] Aqueous zinc-iodine batteries (ZIBs) possess excellent safety, eco-friendliness, low manufacturing cost, and high energy density, making them a strong contender for next-generation green energy batteries. For example, patent application CN113725414A discloses an aqueous zinc-iodine battery cathode material, its cathode, and an aqueous zinc-iodine battery; patent application CN114267828A discloses a derived porous carbon as a zinc-iodine battery cathode material and its preparation method; and patent application CN113036144A discloses a highly stable zinc-iodine battery cathode composite material, its preparation method, and its application.

[0003] However, due to the free dissolution and diffusion of polyiodides generated by the iodine cathode in the aqueous electrolyte during cycling, aqueous zinc-iodine secondary batteries exhibit short lifetimes and rapid self-discharge. To address this issue, numerous iodine host materials, such as carbon matrices, organic polymers, MXenes, and Prussian blue analogs, have been used to suppress the dissolution and diffusion of polyiodides. It is worth noting that constructing composite electrodes using these materials with iodine typically requires a cumbersome and complex process, including the following stages: 1) incorporating iodine into the host material; 2) preparing the electrode slurry; 3) uniformly coating the slurry onto the current collector; and 4) drying the electrode sheet. Such time-consuming steps undoubtedly hinder the further widespread application of ZIBs. Therefore, developing rapidly prepared iodine cathode materials without shuttle effects will be a crucial component in accelerating the application of ZIBs. Summary of the Invention

[0004] This invention addresses the cumbersome and complex preparation process of zinc-iodine battery cathode materials by providing an aqueous zinc-iodine battery cathode material based on amphiphilic molecules, its preparation method, and the battery itself. This invention utilizes a thin film formed by the self-spreading of amphiphilic organic small molecules on the water surface to achieve the direct preparation of the zinc-iodine battery cathode material. Furthermore, the long-chain hydrophobic tails of the amphiphilic organic small molecules prevent the thin-film electrode from dissolving in the aqueous electrolyte, while the hydrophilic heads contain appropriate functional groups (such as amine groups) that can capture and restrict polyiodides during battery charging and discharging, thereby ensuring stable and continuous battery operation.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] This invention provides a rapidly prepared aqueous zinc-iodine secondary battery cathode material, the cathode material comprising Super P conductive agent and oleylamine.

[0007] In one embodiment of the present invention, the mass ratio of Super P conductive agent to oleylamine is 1:20-60. Preferably, it is 1:30-60; more preferably, it is 40-60.

[0008] This invention also provides a method for preparing an amphiphilic molecular-based thin-film cathode for zinc-iodine batteries, comprising the following steps:

[0009] a. Prepare the materials according to the ratio of the conductive agent and the positive electrode active material mentioned above, and mix the prepared materials evenly by stirring to obtain the positive electrode slurry;

[0010] b. The positive electrode slurry obtained in step a is evenly dropped onto the surface of deionized water at a temperature of 10-25°C, so that the positive electrode slurry is evenly spread on the surface of deionized water to form a stable film.

[0011] c. Use a current collector to retrieve the film, and you will obtain the positive electrode of the zinc-iodine battery.

[0012] In one embodiment of the present invention, the current collector is titanium foil, titanium mesh, steel mesh, steel foil, carbon cloth, or carbon paper;

[0013] The present invention also provides a zinc-iodine battery amphiphilic molecular-based thin film cathode based on the above method.

[0014] The present invention also provides an aqueous zinc-iodine secondary battery comprising the above-mentioned thin-film positive electrode, wherein the above-mentioned thin-film positive electrode can be used as the positive electrode material.

[0015] In one embodiment of the present invention, the zinc-iodine secondary battery further includes a negative electrode, a separator, and an electrolyte; the negative electrode provides a complete circuit for the battery; the separator is located between the positive and negative electrodes to prevent short circuits in the battery; and the electrolyte is a mixture of a soluble salt of zinc and potassium iodide.

[0016] In one embodiment of the present invention, the electrolyte is used as an ion transport carrier and is quantitatively added to the battery during battery packaging. The amount of electrolyte added is 10-20 μL / mg of positive electrode material.

[0017] According to the above-described aqueous zinc-iodine secondary battery, the negative electrode is any one of zinc-plated carbon material, zinc alloy, zinc foil, zinc alloy foil, zinc powder, and zinc alloy powder; the separator is a glass fiber separator or filter paper; the soluble salt of zinc is at least one of zinc sulfate, zinc trifluoromethanesulfonate, zinc chloride, zinc acetate, or zinc nitrate; the concentration of the soluble salt of zinc in the electrolyte is 0.5–5 M; and the concentration of potassium iodide in the electrolyte is 0.1–1 M.

[0018] The present invention also provides the application of the above-mentioned battery in the field of new energy.

[0019] Beneficial effects:

[0020] The amphiphilic molecule used in this invention has a long-chain hydrophobic tail that prevents the thin-film electrode from dissolving in the aqueous electrolyte. Meanwhile, the amine functional groups in the hydrophilic head can capture and restrict polyiodides during battery charging and discharging, thus avoiding severe capacity degradation, low iodine utilization, and rapid self-discharge. This significantly improves the electrochemical performance of the zinc-iodine battery, enabling it to withstand over 2000 cycles. Furthermore, the raw materials used in this invention are widely available and inexpensive, meeting the requirements for large-scale production. In addition, this invention proposes a concept of using amphiphilic molecules as the iodine host in aqueous zinc-iodine batteries. By simply mixing the amphiphilic molecules with a conductive agent and allowing them to spread on the water surface, a thin-film cathode material with excellent energy storage performance can be obtained, greatly simplifying the electrode material preparation process and saving significant manpower and material costs. Therefore, the zinc-iodine battery cathode material prepared by this invention represents a significant technological advancement and is expected to accelerate the practical development of aqueous zinc-iodine secondary batteries. Attached Figure Description

[0021] Figure 1 This refers to the thin-film electrode formation process.

[0022] Figure 2 The graph shows the cycle performance of the zinc-iodine battery in Example 1 (current density 0.5 mA cm⁻¹). -2 ).

[0023] Figure 3 The rate performance graph of the zinc-iodine battery in Example 1 (current density from 0.1, 0.2, 0.5, 1.0, 0.1, 0.2, 0.5 mA cm⁻¹) -2 (Changes sequentially).

[0024] Figure 4 The graph shows the cycle performance of the zinc-iodine battery in Example 2 (current density 0.3 mA cm⁻¹). -2 ).

[0025] Figure 5 This is a morphology diagram of the cathode material in Comparative Example 1. Detailed Implementation

[0026] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0027] Example 1

[0028] This invention relates to a positive electrode material for aqueous zinc-iodine secondary batteries. The positive electrode material is composed of Super P conductive agent and oleylamine, with an addition ratio of 1:40 based on mass.

[0029] The preparation method of the positive electrode described in this embodiment includes the following detailed steps:

[0030] a. Prepare the materials according to the above ratio of Super P conductive agent and oleylamine, and mix the prepared materials evenly by stirring to obtain the positive electrode material slurry;

[0031] b. Distribute the positive electrode slurry obtained in step a evenly onto the surface of deionized water at 20°C, allowing the slurry to spread uniformly and form a stable film (as shown in the attached image). Figure 1 (As shown).

[0032] c. Use carbon paper to remove the film to obtain the positive electrode of the zinc-iodine battery.

[0033] The aqueous zinc-iodine secondary battery described in this embodiment includes a positive electrode, a negative electrode, a separator, and an electrolyte. The negative electrode is a commercially available high-purity zinc sheet, the electrolyte is an aqueous solution of 1M ZnSO4 and 0.1M KI, and the separator is a glass fiber separator. The above-prepared positive electrode, negative electrode, glass fiber separator, and electrolyte are assembled into an aqueous zinc-iodine secondary battery in a CR2032 button cell assembly. When assembling the battery, the separator is located between the positive electrode and the negative electrode, and the electrodes are stacked in the order of positive electrode, separator, and negative electrode to form a sandwich-like structure.

[0034] After the prepared aqueous zinc-iodine secondary battery was left to stand for 12 hours, it maintained a voltage between 0.6 and 1.6 V at a current of 0.5 mA cm⁻¹. -2 Electrochemical tests were performed using the current density. The initial discharge specific capacity was 80.9 mAh g. -1 After 2000 constant current charge-discharge cycles, the discharge specific capacity is 60.9 mAh g. -1 The capacity retention rate is approximately 75.3% (see attached). Figure 2 (As shown). Rate performance was tested in the voltage range of 0.6–1.6V, with current densities of 0.1, 0.2, 0.5, 1.0, 0.1, 0.2, and 0.5 mA cm⁻¹, respectively. -2 The current density increased from 0.1 to 1.0 mA cm⁻¹ -2 The capacity retention rate was 53.1% (see attached). Figure 3 (As shown).

[0035] Example 2

[0036] This invention relates to a positive electrode material for aqueous zinc-iodine secondary batteries. The positive electrode material is composed of Super P conductive agent and oleylamine, with an addition ratio of 1:60 based on mass.

[0037] The preparation method of the positive electrode described in this embodiment includes the following detailed steps:

[0038] a. Prepare the materials according to the above ratio of Super P conductive agent and oleylamine, and mix the prepared materials evenly by stirring to obtain the positive electrode material;

[0039] b. Stir the positive electrode material obtained in step a at 20°C to form a viscous liquid, and then quickly drop it onto the surface of deionized water to make the positive electrode slurry spread evenly on the surface of deionized water and form a stable film.

[0040] c. Use carbon paper to remove the film to obtain the positive electrode of the zinc-iodine battery.

[0041] The aqueous zinc-iodine secondary battery described in this embodiment includes a positive electrode, a negative electrode, a separator, and an electrolyte. The negative electrode is a commercially available high-purity zinc sheet, the electrolyte is an aqueous solution of 1M ZnSO4 and 0.1M KI, and the separator is a glass fiber separator. The above-prepared positive electrode, negative electrode, glass fiber separator, and electrolyte are assembled into an aqueous zinc-iodine secondary battery in a CR2032 button cell assembly. During battery assembly, the separator is located between the positive and negative electrodes and is stacked in the order of positive electrode, separator, and negative electrode to form a sandwich-like structure.

[0042] After the prepared aqueous zinc-iodine secondary battery was left to stand for 12 hours, it maintained a voltage between 0.6 and 1.6 V at a current of 0.3 mA cm⁻¹. -2 Electrochemical tests were conducted using the current density. However, due to the low carbon content of the material, the battery required a long activation period before its capacity stabilized; its discharge specific capacity after 200 constant current charge-discharge cycles was 93.3 mAh g. -1 The capacity retention rate is approximately 100.0% (see attached). Figure 4 (As shown).

[0043] In existing technologies, the literature "Anchoring Polyiodide to Conductive Polymers as Cathode for..." The polyaniline cathode reported in "Performance Aqueous Zinc-Iodine Batteries" retains approximately 79% of the battery capacity after 700 cycles; the sulfur and nitrogen enriched graphene foam scaffolds for aqueous rechargeable zinc-iodine battery reported approximately 81% of the battery capacity after 500 cycles; the biomass-derived hierarchically porous carbon cathode reported approximately 87% of the battery capacity after 1000 cycles; and the ZIF-8 derived porous carbon cathode reported approximately 72% of the battery capacity after 1000 cycles.

[0044] As can be seen, this invention proposes a concept of using amphiphilic molecules as iodine hosts in aqueous zinc-iodine batteries. By simply mixing the amphiphilic molecules with a conductive agent and allowing them to spread on the water surface, a thin-film cathode material with energy storage performance comparable to or even better than existing complex systems can be obtained. This greatly simplifies the preparation process and technology of electrode materials and saves a lot of manpower and material costs.

[0045] Comparative Example 1

[0046] This invention relates to an aqueous zinc-iodine secondary battery positive electrode material, wherein the positive electrode material is composed of Super P conductive agent and oleylamine, and the addition ratio is 1:20 based on mass.

[0047] The preparation method of the positive electrode described in this embodiment includes the following detailed steps:

[0048] a. Prepare the materials according to the above ratio of Super P conductive agent and oleylamine, and mix the prepared materials evenly by stirring to obtain the positive electrode material;

[0049] b. Stir the positive electrode material obtained in step a at 20°C to form a viscous liquid, and then quickly drop it onto the surface of deionized water.

[0050] c. Use carbon paper to remove the material to obtain the positive electrode of the zinc-iodine battery.

[0051] As attached Figure 5 As shown, at this ratio, the high carbon content leads to increased material viscosity, resulting in the prepared aqueous zinc-iodine secondary battery cathode material exhibiting an aggregated state and failing to form a thin film.

[0052] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A method for preparing an amphiphilic molecular-based thin-film cathode for zinc-iodine batteries, characterized in that, Includes the following steps: a. Mix Super P conductive agent and oleylamine evenly by stirring to obtain a positive electrode slurry; the mass ratio of Super P conductive agent to oleylamine is 1:30-60; b. The positive electrode slurry obtained in step a is evenly dropped onto the surface of deionized water at a temperature of 10-25 ℃, so that the positive electrode slurry is evenly spread on the surface of deionized water to form a stable film. c. Use a current collector to retrieve the film, thus obtaining the positive electrode of the zinc-iodine battery.

2. The method according to claim 1, characterized in that, The current collector is titanium foil, titanium mesh, steel mesh, steel foil, carbon cloth, or carbon paper.

3. The method according to claim 1, characterized in that, The mass ratio of Super P conductive agent to oleylamine is 1:40-60.

4. A zinc-iodine battery amphiphilic molecular-based thin film cathode prepared by the method of claim 1 or 2.

5. An aqueous zinc-iodine secondary battery, characterized in that, The zinc-iodine battery amphiphilic molecular-based thin film cathode as described in claim 4 is used as the cathode material.

6. The aqueous zinc-iodine secondary battery according to claim 5, characterized in that, The aqueous zinc-iodine secondary battery also includes a negative electrode, a separator, and an electrolyte; the negative electrode provides a complete circuit for the battery; the separator is located between the positive and negative electrodes to prevent short circuits; the electrolyte is a mixture of a soluble salt of zinc and potassium iodide.

7. The aqueous zinc-iodine secondary battery according to claim 6, characterized in that, The electrolyte, as an ion transport carrier, is quantitatively added to the battery during battery packaging. The amount of electrolyte added is 10–20 μL / mg of positive electrode material.

8. The aqueous zinc-iodine secondary battery according to claim 6, characterized in that, The negative electrode is any one of zinc-plated carbon material, zinc alloy, zinc foil, zinc alloy foil, zinc powder, and zinc alloy powder; the diaphragm is a glass fiber diaphragm or filter paper; the soluble salt of zinc is at least one of zinc sulfate, zinc trifluoromethanesulfonate, zinc chloride, zinc acetate, or zinc nitrate; the concentration of the soluble salt of zinc in the electrolyte is 0.5–5 M; the concentration of potassium iodide in the electrolyte is 0.1–1 M.

9. The application of the aqueous zinc-iodine secondary battery according to any one of claims 5-8 in the field of new energy.

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