Method for preparing positive electrode material of zinc-iodine battery
By growing cobalt tetroxide on carbon cloth and loading iodine in the gas phase, the problem of uniform mixing of iodine in the cathode material of zinc-iodine battery was solved, achieving efficient electron transport and cycle stability, and improving battery performance.
Patent Information
- Application Number
- CN202511720402.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-21
- Publication Date
- 2026-02-24
AI Technical Summary
Existing technologies cannot effectively suppress the shuttle effect of iodine in the cathode material of aqueous zinc-iodine batteries, resulting in the inability of iodine active materials to mix uniformly, poor contact, and the formation of 'dead iodine'. Furthermore, traditional preparation methods are unable to achieve uniform morphology at the nanoscale, which affects battery performance.
Cobalt tetroxide (Co3O4) was grown on carbon cloth using a co-precipitation method, and then iodine was loaded into the gas phase to prepare a zinc-iodine battery cathode material. The metal-organic framework structure was used to promote electron transport of iodine and improve the efficiency of redox reaction.
It significantly improves the electrochemical performance of zinc-iodine battery cathode materials, increases battery capacity and cycle stability, suppresses the shuttle effect of iodine, and improves the rate performance of the materials.
Smart Images
Figure CN121565774A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrode technology, and in particular relates to a method for preparing a zinc-iodine battery cathode material. Background Technology
[0002] Currently, the severe energy problem is driving the continuous search for advanced energy storage systems that are efficient, economical, environmentally friendly, and have long cycle life. Lithium-ion batteries are widely used in new energy vehicles and portable electronic devices, occupying a large market share. However, the scarcity of lithium-ion resources, flammability, and toxic organic electrolytes hinder their application. Meanwhile, Li... + During repeated insertion and extraction, the cathode structure is prone to collapse, and the lithium metal anode is susceptible to dendrite growth and passivation reactions, resulting in poor cycle stability. Therefore, there is an urgent need to develop safe, reliable, and low-cost alternatives to meet the demands of next-generation electronic products.
[0003] Aqueous zinc batteries have a high theoretical capacity (820mAh g). -1 Zinc, with its abundant zinc capacity, low electrode potential (-0.76V), and good stability in air, is considered one of the most promising candidate batteries. Currently, zinc-air batteries and zinc-halogen batteries have been developed with the aim of improving energy and power density. I2 has very low solubility in water, making it suitable for use in aqueous batteries. Unlike traditional zinc batteries that typically rely on the insertion and extraction of zinc ions, aqueous zinc-iodine batteries (Zn-I2) store energy through the redox reaction of iodine at the positive electrode and the deposition / stripping of zinc at the negative electrode. Applying iodine redox electrochemistry to zinc-based aqueous batteries could potentially improve their potential and voltage, and potentially increase their capacity to 211 mAh g⁻¹. −1 The theoretical capacity of zinc-iodine batteries has attracted widespread attention; furthermore, the multiple valence states of iodine (such as −1, 0, +1, +3, +5, and +7) give it great theoretical potential for multi-electron conversion reactions. In the past few years, zinc-iodine batteries have made great progress in developing cathode materials with high specific capacity and long lifespan, mainly focusing on various carbon materials, single-atom materials, coordination materials, and conductive polymers.
[0004] The core reaction of aqueous zinc-iodine batteries is I₂ / I₂. - With Zn / Zn 2+ The reversible electrochemical conversion between chemical energy and electrical energy is the key feature of a secondary battery. It uses zinc sulfate as the electrolyte, which gives it advantages such as high safety, low cost, and environmental friendliness.
[0005] To construct excellent aqueous zinc-iodine battery cathode materials, the following points must be met: efficient suppression of polyiodide shuttle (confining iodine and its reaction intermediates to the cathode region to the greatest extent possible), provision of a superior conductive network (providing a continuous and efficient electron transport path), excellent zinc affinity and ion transport capabilities (reducing interfacial impedance), and maintenance of a stable mechanical and chemical structure (preventing structural collapse and ensuring long cycle life). The selection of aqueous zinc-iodine battery cathode materials mainly falls into five categories: carbon-based materials, polar metal compounds, conductive polymers, and composite materials.
[0006] Currently, carbon-based materials are considered suitable for use as cathodes in aqueous zinc-iodine batteries due to their excellent electrical conductivity and adjustable specific surface area / porosity. However, traditional electrode preparation methods (slurry coating, solution impregnation, etc.) have weak bonding forces and mainly rely on physical mixing, which cannot achieve uniform mixing, tight bonding, and effective encapsulation of iodine active materials and cathode materials. As a result, the "shuttle effect" cannot be eliminated. At the same time, traditional electrode preparation methods are difficult to achieve nanoscale uniform morphology, which easily leads to the formation of large iodine agglomerates on the outer surface or large pores of the cathode material. These agglomerates have poor contact with the conductive network and cannot be fully utilized in the reaction, thus forming "dead iodine." They are also the main source of polyiodine compound shuttle. Slurry coating methods also cannot prevent dissolved polyiodides from diffusing out of the pores of the material (even porous carbon). Summary of the Invention
[0007] The purpose of this invention is to provide a method for preparing zinc-iodine battery cathode materials, aiming to solve the problems mentioned in the background art.
[0008] The present invention is implemented as follows: a method for preparing a zinc-iodine battery cathode material includes the following steps: (1) After cutting the carbon cloth, clean and dry it, and then anneal it. (2) Dissolve 2-methylimidazole and cobalt nitrate in methanol to prepare a ZIF-67 precursor solution; (3) The treated carbon cloth and ZIF-67 precursor solution were co-precipitated and then subjected to high-temperature treatment after standing. Co3O4 was co-precipitated and grown on the carbon cloth. (4) After drying the carbon cloth, cut it into round pieces, mix it with iodine and place it in a container to obtain Co3O4 loaded with iodine, which is recorded as sample I2@Co3O4. Then heat it, cool it down and continue heating to remove the iodine on the surface, and obtain the zinc-iodine battery cathode material.
[0009] This invention provides a method for preparing a zinc-iodine battery cathode material. A carbon-based material is selected as the carrier, and cobalt tetroxide is grown on carbon cloth using a co-precipitation method (the cathode material with a capacity of nearly 200 mAh / g produced by co-precipitation of Co3O4 is shown to be 200 mAh / g). -1 Iodine was loaded into the gas phase to prepare the positive electrode material for aqueous zinc-iodine batteries. The metal-organic framework structure effectively loaded iodine, promoted the electron transport of iodide ions, and thus enhanced the redox reaction of iodine, thereby increasing the electrochemical performance. Attached Figure Description
[0010] Figure 1 The XRD pattern of Co3O4 provided in Embodiment 1 of the present invention; Figure 2 The XRD pattern of CoS provided in Comparative Example 1 of this invention; Figure 3 This is a SEM image of the ZIF-67 precursor provided in Embodiment 1 of the present invention; Figure 4 This is a SEM image of CoS provided in Comparative Example 1 of the present invention; Figure 5 The Raman spectrum of I2@CoS provided in Comparative Example 1 of this invention; Figure 6 The Raman spectrum of I2@Co3O4 provided in Embodiment 1 of the present invention; Figure 7 The charge-discharge diagrams of the I2@Co3O4 and I2@CoS cathode materials provided in Embodiment 1 and Comparative Example 1 of this invention are shown below. Figure 8 Rate maps of the I2@Co3O4 and I2@CoS cathode materials provided in Example 1 and Comparative Example 1 of the present invention under different rate conditions; Figure 9 The I2@CoS cathode material provided in Comparative Example 1 of this invention operates at 0.5 mV / s. -1 CV curve under the given conditions; Figure 10 The I2@Co3O4 cathode material provided in Example 1 of this invention operates at 0.5 mV / s. -1 CV curve under the given conditions; Figure 11 The I2@CoS cathode material provided in Comparative Example 1 of this invention was subjected to 10 charge-discharge cycles at 1C. Figure 12 The I2@Co3O4 cathode material provided in Example 1 of this invention was subjected to 10 charge-discharge cycles at 1C. Detailed Implementation
[0011] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0012] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.
[0013] Example 1: A zinc-iodine battery cathode material (I2@Co3O4), the preparation method of which includes the following steps: Step 1: Cut commercial carbon cloth into 1.5cm*1.5cm pieces, wash with acetone, alcohol and deionized water and dry for 12 hours, then place in two magnetic boats and heat in a muffle furnace at 450℃ for 150 minutes. Step 2: Dissolve 328 mg of 2-methylimidazole and 249 mg of cobalt nitrate in 20 ml of methanol to prepare the ZIF-67 precursor solution; Step 3: Using the carbon cloth from Step 1 and the solution from Step 2, let it stand for 24 hours to dry using the co-precipitation method, and then put it into a muffle furnace at 400℃ for 1 hour to generate Co3O4 on the surface of the carbon cloth. Step 4: After drying the carbon cloth from Step 3, cut it into round pieces with a diameter of 1.2cm. Step 5: Mix the carbon cloth from Step 4 with iodine (after thorough grinding) and place it in a small vial to obtain iodine-loaded Co3O4, denoted as sample I2@Co3O4; Step 6: Place the sample from Step 5 into a forced-air drying oven and heat at 120℃ for 4 hours; Step 7: After taking out the sample from Step 6, place it in a petri dish and continue heating at 80°C for 1 hour (to remove the iodine on the surface). This will prepare the working electrode. The mass of the electrode material I2@Co3O4 active material is approximately 1.5 mg.
[0014] Comparative Example 1: A zinc-iodine battery cathode material (I2@CoS), the preparation method of which includes the following steps: Step 1: Cut commercial carbon cloth into 1.5cm*1.5cm pieces, wash with acetone, alcohol and deionized water and dry for 12 hours, then place in two magnetic boats and heat in a muffle furnace at 450℃ for 150 minutes. Step 2: Weigh 0.2974g of cobalt chloride and 1.427g of thiourea and put them into 250mL of water; Step 3: Using the carbon cloth from Step 1 and the solution from Step 2, perform CoS electrodeposition using cyclic voltammetry. Specifically, take 25 ml of the solution and use the Chenhua workstation for electrodeposition. The electrodeposition of cobalt sulfide is performed using the CV method, with a potential window of -1.24 to 0.16 V, a scan rate of 5 mV / s, a three-electrode system, and 10 cycles. Step 4: After drying the carbon cloth from Step 3, cut it into round pieces with a diameter of 1.2cm. Step 5: Mix the carbon cloth from Step 4 with iodine (after thorough grinding) and place it in a vial to obtain CoS-loaded iodine, denoted as sample I2@CoS; Step 6: Place the sample from Step 5 into a forced-air drying oven and heat at 120℃ for 4 hours; Step 7: After taking out the sample from Step 6, place it in a petri dish and continue heating at 80°C for 1 hour (to remove the iodine on the surface). This will prepare the working electrode. The mass of the electrode material I2@CoS active material is approximately 2 mg.
[0015] Performance testing: The Co3O4 prepared in Example 1 was analyzed, and the XRD pattern was obtained as follows. Figure 1 As shown, Figure 1 XRD card 78-1970 matching Co3O4 confirms the successful synthesis of Co3O4 using the ZIF-67 precursor in Example 1. The ZIF-67 precursor of Example 1 was analyzed, and the SEM image is shown below. Figure 3 As shown, SEM characterization revealed that the morphology was a regular dodecahedron shape and uniformly distributed, indicating that the morphology formation of the precursor met the expected results. The CoS of Comparative Example 1 was analyzed, and the XRD pattern was obtained as follows: Figure 2 As shown in the figure, the SEM image is as follows: Figure 4 As shown, Figure 2 The three strong peaks of 65-0407 on the XRD card of CoS confirm the successful growth of CoS on carbon-based materials. SEM characterization shows that CoS was successfully generated on carbon-based materials with a nano-morphology. The Raman spectrum of CoS gas-phase loaded with iodine in Comparative Example 1 is as follows: Figure 5 As shown, the Raman shift at 100 nm -1 and 150 nm -1 The nearby characteristic peaks correspond to the characteristic vibrational peaks of iodine molecules (I2), indicating that gas-loaded iodine was successfully deposited on the CoS surface and exists in the form of molecular I2. The Raman spectrum of iodine loaded in the gas phase of Co3O4 in Example 1 is as follows: Figure 6 As shown in the graph, at 160 cm... -1 The presence of a distinct peak nearby can be attributed to the characteristic Raman peak of the I2 molecule, indicating that the gas-supported iodine exists in the form of molecular (I2) on the surface of Co3O4 and has good vibrational activity. The charge-discharge diagrams of the I2@Co3O4 and I2@CoS cathode materials provided in Example 1 and Comparative Example 1 are as follows: Figure 7As shown in the charge-discharge comparison chart of the two materials, it can be seen that the battery capacity made with the co-precipitated Co3O4 cathode material is 50 mAh higher than that made with the electrode material of electrodeposited CoS. -1 ; The rate scaling diagrams of the I2@Co3O4 and I2@CoS cathode materials provided in Example 1 and Comparative Example 1 under different rate conditions are shown below. Figure 8 As shown in the charge-discharge comparison chart of the two materials, it can be seen that the battery capacity made with the co-precipitated Co3O4 cathode material is 50 mAh higher than that made with the electrode material of electrodeposited CoS. -1 ; The I2@CoS cathode material provided in Comparative Example 1 operates at 0.5 mV / s. -1 The CV curve under the given conditions is shown in the figure. Figure 9 As shown; the I2@Co3O4 cathode material provided in Example 1 at 0.5 mVs -1 The CV curve under the given conditions is shown in the figure. Figure 10 As shown; according to Figure 9 and Figure 10 It can be seen that the redox peak symmetry of the I2@Co3O4 cathode material is better, indicating that its reaction is more reversible. The peak shape of the oxidation peak is sharper and fuller, indicating that the kinetic process of the oxidation reaction is more efficient and the charge transfer resistance is smaller. In contrast, I2@CoS is weaker than I2@Co3O4 in terms of reversible reaction activity, indicating that its performance of gas-phase iodine loading after co-precipitation of cobalt tetroxide is better than that of electrodeposited cobalt sulfide. The results of 10 charge-discharge cycles of the I2@CoS cathode material provided in Comparative Example 1 under 1C conditions are as follows: Figure 11 As shown in the figure, the capacity of I2@CoS decreases significantly, dropping to 150mAh in the last five cycles. -1 the following; The I2@CoS cathode material provided in Example 1 under 1C conditions for 10 charge-discharge cycles is as follows: Figure 12 As shown in the figure, it can be seen that I2@Co3O4 is stable at 200 mAh g during the cycling process. -1 This indicates that the cathode material prepared by the co-precipitation method has higher stability and capacity.
[0016] In summary, the co-precipitation method used in the embodiments of the present invention can more effectively improve battery capacity, suppress the shuttle effect of iodine, and improve its rate performance. When applied to the preparation of zinc-iodine battery cathode materials, it significantly improves the capacity, rate performance and cycle stability of the materials.
[0017] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing a zinc-iodine battery cathode material, characterized in that, Includes the following steps: (1) After cutting the carbon cloth, clean and dry it, and then anneal it. (2) Dissolve 2-methylimidazole and cobalt nitrate in methanol to prepare a ZIF-67 precursor solution; (3) The treated carbon cloth and ZIF-67 precursor solution were co-precipitated and then subjected to high-temperature treatment after standing. Co3O4 was co-precipitated and grown on the carbon cloth. (4) After drying the carbon cloth, cut it into round pieces, mix it with iodine and place it in a container to obtain Co3O4 loaded with iodine, which is recorded as sample I2@Co3O4. Then heat it, cool it down and continue heating to remove the iodine on the surface, and obtain the zinc-iodine battery cathode material.
2. The method for preparing zinc-iodine battery cathode material according to claim 1, characterized in that, In step (1), the specific process of the annealing treatment is as follows: the cleaned and dried carbon is arranged in two magnetic boats and heated in a muffle furnace at 450°C for 150 min.
3. The method for preparing zinc-iodine battery cathode material according to claim 1, characterized in that, In step (1), the specific process of cleaning and drying is as follows: cleaning with acetone, alcohol and deionized water in sequence and then drying for 12 hours.
4. The method for preparing zinc-iodine battery cathode material according to claim 1, characterized in that, Step (3) is as follows: Place the carbon cloth in the ZIF-67 precursor solution and let it stand for 24 hours. After 24 hours, the carbon cloth is removed and dried, then placed in a muffle furnace for annealing at 400°C for 1 hour to generate Co3O4 on the surface of the carbon cloth.
5. The method for preparing zinc-iodine battery cathode material according to claim 1, characterized in that, In step (4), the specific process of the heat treatment is as follows: place the sample in a forced-air drying oven and heat at 120°C for 4 hours.
6. The method for preparing zinc-iodine battery cathode material according to claim 4, characterized in that, In step (4), the specific process of continuing to heat after cooling is as follows: take the sample out of the drying oven, place it in a petri dish, and continue heating at 80°C for 1 hour.