Iodine-loaded positive electrode for zinc-iodine battery as well as preparation method and application of iodine-loaded positive electrode

Abstract

The invention relates to an iodine-loaded positive electrode for a zinc-iodine battery and a preparation method and application of the iodine-loaded positive electrode, and belongs to the technical field of positive electrode materials for zinc-iodine batteries. The preparation method of the iodine-loaded positive electrode for the zinc-iodine battery comprises the following steps: mixing an iodine-loaded carbon material, conductive carbon black, a polysaccharide binder and deionized water in proportion, grinding into slurry, uniformly coating a current collector with the slurry, and drying to obtain the iodine-loaded positive electrode for the zinc-iodine battery. As the polysaccharide binder is rich in a large number of active functional groups (hydroxyl, carboxyl and the like), dissolution of active iodine and a shuttle effect of polyiodide can be inhibited through a chemical adsorption effect, corrosion to a zinc negative electrode caused by attenuation of battery capacity and shuttle of the polyiodide is avoided, and the polysaccharide binder has a good application prospect in the zinc-iodine battery.

Description

Technical Field

[0001] The present application relates to the technical field of positive electrode materials for zinc-iodine batteries, and in particular to an iodine-loaded positive electrode for zinc-iodine batteries, and a preparation method and application thereof. Background Art

[0002] Aqueous zinc-based batteries are considered to be one of the ideal electrochemical energy storage devices due to their inherent advantages such as cost-effectiveness, high operational safety, and environmental friendliness. The choice of cathode material (vanadium-based oxide / manganese-based oxide / iodine-loaded composite material) determines the electrochemical performance of zinc-based batteries. Among them, iodine cathode materials have attracted widespread attention due to their advantages such as abundant resources, large theoretical capacity, high redox potential, and rich redox valence states. However, zinc-iodine batteries (ZIBs) have problems such as active iodine dissolution and multi-iodide shuttle effect during the charge and discharge process, resulting in severe self-discharge, rapid attenuation of specific capacity, and even electrochemical corrosion of the zinc negative electrode, which greatly limits the further development of ZIBs.

[0003] At present, many strategies have been implemented to solve the above problems. For example, the skeleton structure of the iodine-loaded positive electrode is adjusted to physically limit the dissolution of active iodine, but there is usually a complex material preparation process. The use of high-concentration electrolytes can effectively limit the reactivity of active iodine, but it slows down the ion migration kinetics of ZIBs and increases the manufacturing cost. The design of functional membranes has solved the problem of polyiodide shuttling well, but its effectiveness and long-term cycle stability depend entirely on the integrity of the coating. As an important basic component of the iodine-loaded positive electrode, the binder is the most cost-effective option compared to the previous route by designing a new functional binder and utilizing the strong chemical adsorption of iodine species by the rich active functional groups in the binder material to inhibit the dissolution of active iodine and the shuttling effect of polyiodides.

[0004] However, conventional PTFE binders for batteries are composed of highly chemically inert C-H bonds, providing only physical bonding in batteries and showing little chemical adsorption for polyiodides. Therefore, there is a need to develop new functional binders that exhibit chemical adsorption for polyiodides.

[0005] The existing Chinese patent with publication number CN115244738 A discloses a binder for lithium-ion battery positive electrodes, a slurry for forming a lithium-ion battery positive electrode mixture layer, a lithium-ion battery positive electrode, and a lithium-ion battery. This method utilizes the excellent mechanical strength of polysaccharide binders to achieve good physical adhesion to lithium-ion batteries, thereby increasing the cycle life of lithium-ion batteries. However, polysaccharide binders only play a physical bonding role in lithium-ion batteries. Compared with lithium-ion batteries, the use of polysaccharide binders in iodine-loaded positive electrodes of zinc-iodine batteries, in addition to providing mechanical stability, can also suppress the shuttle effect of polyiodide during the charge and discharge process of zinc-iodine batteries through the strong chemical adsorption of iodine species by the abundant active functional groups in the polysaccharide binders, thereby enhancing the zinc-iodine battery's anti-self-discharge ability, rate performance, and cycle stability. Summary of the Invention

[0006] In view of this, the present application provides an iodine-loaded positive electrode for zinc-iodine batteries, and a preparation method and application thereof. Since the polysaccharide binder is rich in a large number of active functional groups (hydroxyl groups, carboxyl groups, etc.), it can inhibit the dissolution of active iodine and the shuttle effect of polyiodides through chemical adsorption, thereby avoiding the attenuation of battery capacity and the corrosion of the zinc negative electrode by the shuttle of polyiodides. It has good application prospects in zinc-iodine batteries and can effectively overcome the defects of the above-mentioned prior art.

[0007] The first aspect of the present application provides a method for preparing an iodine-loaded positive electrode for a zinc-iodine battery, comprising the following steps:

[0008] The iodine-loaded carbon material, conductive carbon black, polysaccharide binder and deionized water are mixed in proportion and then ground into slurry, the slurry is evenly coated on a current collector, and the iodine-loaded positive electrode of the zinc-iodine battery is obtained after drying.

[0009] Preferably, the polysaccharide binder is at least one selected from sodium alginate, carboxymethyl chitosan, sodium hyaluronate, hydroxypropyl methylcellulose, dextran 70, guar gum, locust bean gum, and konjac gum.

[0010] Preferably, the mass ratio of the iodine-loaded carbon material, the conductive carbon black and the polysaccharide binder is 7:2:1.

[0011] Preferably, the grinding time is 30-60 min.

[0012] Preferably, the iodine-loaded carbon material is a commercial activated carbon-iodine elemental composite material, and its specific preparation process is as follows:

[0013] Commercial activated carbon and elemental iodine were heated at 120°C for 6 hours to prepare iodine-loaded carbon material.

[0014] Preferably, the conductive carbon black is Ketjen black; and the current collector is a circular stainless steel mesh with a diameter of 12 mm.

[0015] Preferably, the drying temperature is 40-60° C., and the drying time is 6-8 hours.

[0016] Preferably, the loading amount of iodine active substance is 1-2 mg cm -2 .

[0017] The second aspect of the present application also provides an iodine-loaded positive electrode for a zinc-iodine battery, which is prepared by the above-mentioned method.

[0018] The third aspect of the present application further provides a zinc-iodine battery, which has the above-mentioned iodine-loaded positive electrode for the zinc-iodine battery.

[0019] Compared with the prior art, this application has the following beneficial effects:

[0020] The polysaccharide binder used in this application has high abundance in natural resources, low cost, and is environmentally friendly. Its large-scale application is of great significance to promoting the commercial development of zinc-iodine batteries. In addition, the abundant active functional groups such as hydroxyl and carboxyl groups in the polysaccharide binder have a strong chemical adsorption effect on polyiodides, thereby inhibiting the shuttle effect of polyiodides during the charging and discharging process of the zinc-iodine battery, avoiding battery capacity decay and corrosion of the zinc metal negative electrode by polyiodides, and thereby improving the battery's anti-self-discharge ability, rate performance and cycle stability. In addition, the binder component accounts for a low proportion in the battery system, and suppressing the shuttle effect of the zinc-iodine battery through binder engineering has great economic benefits. At the same time, the preparation process of this application is simple and highly repeatable. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the present application or the prior art, the following briefly introduces the drawings required for use in the description of the present application or the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0022] Figure 1 This is a comparison of the cycling performance of zinc-iodine full batteries assembled with the guar gum binder in Example 1 and the PTFE binder in Comparative Example 1 at a current density of 1 A / g;

[0023] Figure 2 This is a comparison of the rate performance of zinc-iodine full batteries assembled with the guar gum binder in Example 1 and the PTFE binder in Comparative Example 1 at current densities of 0.1, 0.2, 0.3, 0.5, 1, 2, and 3 A / g;

[0024] Figure 3This is a comparison of the self-discharge resistance of zinc-iodine full batteries assembled with the guar gum binder in Example 1 and the PTFE binder in Comparative Example 1;

[0025] Figure 4 The guar gum binder in Example 1 and the PTFE binder in Comparative Example 1 were each immersed in I3 - Comparison of UV-visible adsorption intensity of the supernatant in the solution;

[0026] Figure 5 The guar gum binder in Example 1 and the PTFE binder in Comparative Example 1 were each added dropwise with 13 - Comparison of Raman spectra of powder after solution;

[0027] Figure 6 For the guar gum binder in Example 1, add I3 - X-ray photoelectron spectroscopy of the powder before and after solution;

[0028] Figure 7 This is a SEM comparison of zinc sheets of a zinc-iodine full battery assembled with the guar gum binder in Example 1 and the PTFE binder in Comparative Example 1 after 50 charge and discharge cycles at a current density of 1 A / g. DETAILED DESCRIPTION

[0029] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0030] Unless otherwise specified, the experimental methods used in the examples of this application are all conventional methods.

[0031] In the following examples and comparative examples, unless otherwise specified, all raw materials can be purchased commercially or prepared by conventional methods.

[0032] Example 1

[0033] First, 100 mg of commercial activated carbon and iodine were added separately and mixed, and calcined at a temperature of 120° C. for 6 h to prepare an iodine-loaded carbon material.

[0034] Secondly, 35 mg of iodine-loaded carbon material, 10 mg of Ketjen black, and 5 mg of guar gum were uniformly mixed, and 5 mL of water was added as a solvent to grind into a slurry. The grinding time was 30 min.

[0035] The slurry was then evenly coated on a 12 mm round stainless steel mesh and dried in a vacuum drying oven at 40°C for 6 h to produce a positive electrode sheet. The iodine active material loading in the positive electrode sheet was 1.5 mg cm -2 .

[0036] Finally, a 12mm round zinc sheet was used as the negative electrode, glass fiber as the separator, 2M zinc sulfate as the electrolyte, a plate containing guar gum binder as the positive electrode, and 2025 model positive and negative battery shells were assembled into a button-type zinc-iodine full battery.

[0037] Example 2

[0038] First, 100 mg of commercial activated carbon and iodine were added separately and mixed, and calcined at a temperature of 120° C. for 6 h to prepare an iodine-loaded carbon material.

[0039] Secondly, 35 mg of iodine-loaded carbon material, 10 mg of Ketjen black, and 5 mg of sodium alginate were uniformly mixed, and 5 mL of water was added as a solvent to grind into a slurry. The grinding time was 30 min.

[0040] The slurry was then evenly coated on a 12 mm round stainless steel mesh and dried in a vacuum drying oven at 40°C for 6 h to produce a positive electrode sheet. The iodine active material loading in the positive electrode sheet was 1.5 mg cm -2 .

[0041] Finally, a 12mm round zinc sheet was used as the negative electrode, glass fiber as the separator, 2M zinc sulfate as the electrolyte, a pole piece loaded with sodium alginate binder as the positive electrode, and a 2025 model positive and negative battery shell to assemble a button-type zinc-iodine full battery.

[0042] Example 3

[0043] First, 100 mg of commercial activated carbon and iodine were added separately and mixed, and calcined at a temperature of 120° C. for 6 h to prepare an iodine-loaded carbon material.

[0044] Secondly, 35 mg of iodine-loaded carbon material, 10 mg of Ketjen black, and 5 mg of carboxymethyl chitosan were uniformly mixed, and 5 mL of water was added as a solvent to grind them into a slurry. The grinding time was 30 min.

[0045] The slurry was then evenly coated on a 12 mm round stainless steel mesh and dried in a vacuum drying oven at 40°C for 6 h to prepare a positive electrode sheet. The iodine active material loading in the positive electrode sheet was 1.5 mg cm -2 .

[0046] Finally, a 12mm round zinc sheet was used as the negative electrode, glass fiber as the separator, 2M zinc sulfate as the electrolyte, a pole piece loaded with carboxymethyl chitosan binder as the positive electrode, and a 2025 model positive and negative battery shell were assembled into a button-type zinc-iodine full battery.

[0047] Example 4

[0048] First, 100 mg of commercial activated carbon and iodine were added separately and mixed, and calcined at a temperature of 120° C. for 6 h to prepare an iodine-loaded carbon material.

[0049] Next, 35 mg of iodine-loaded carbon material, 10 mg of Ketjen black, and 5 mg of sodium hyaluronate were uniformly mixed, and 5 mL of water was added as a solvent to grind the mixture into a slurry. The grinding time was 30 min.

[0050] The slurry was then evenly coated on a 12 mm round stainless steel mesh and dried in a vacuum drying oven at 40°C for 6 h to prepare a positive electrode sheet. The iodine active material loading in the positive electrode sheet was 1.5 mg cm -2 .

[0051] Finally, a 12mm round zinc sheet was used as the negative electrode, glass fiber as the separator, 2M zinc sulfate as the electrolyte, a pole piece loaded with sodium hyaluronate binder as the positive electrode, and a 2025 model positive and negative battery shell were assembled into a button-type zinc-iodine full battery.

[0052] Example 5

[0053] First, 100 mg of commercial activated carbon and iodine were added separately and mixed, and calcined at a temperature of 120° C. for 6 h to prepare an iodine-loaded carbon material.

[0054] Secondly, 35 mg of iodine-loaded carbon material, 10 mg of Ketjen black, and 5 mg of hydroxypropyl methylcellulose were uniformly mixed, and 5 mL of water was added as a solvent to grind into a slurry. The grinding time was 30 minutes.

[0055] The slurry was then evenly coated on a 12 mm round stainless steel mesh and dried in a vacuum drying oven at 40°C for 6 h to prepare a positive electrode sheet. The iodine active material loading in the positive electrode sheet was 1.5 mg cm -2 .

[0056] Finally, a 12mm round zinc sheet was used as the negative electrode, glass fiber as the separator, 2M zinc sulfate as the electrolyte, a pole piece loaded with hydroxypropyl methylcellulose binder as the positive electrode, and a 2025 model positive and negative battery shell were assembled into a button-type zinc-iodine full battery.

[0057] Example 6

[0058] First, 100 mg of commercial activated carbon and iodine were added separately and mixed, and calcined at a temperature of 120° C. for 6 h to prepare an iodine-loaded carbon material.

[0059] Secondly, 35 mg of iodine-loaded carbon material, 10 mg of Ketjen black, and 5 mg of dextran 70 were uniformly mixed, and 5 mL of water was added as a solvent to grind into a slurry. The grinding time was 30 minutes.

[0060] The slurry was then evenly coated on a 12 mm round stainless steel mesh and dried in a vacuum drying oven at 40°C for 6 h to prepare a positive electrode sheet. The iodine active material loading in the positive electrode sheet was 1.5 mg cm -2 .

[0061] Finally, a 12mm round zinc sheet was used as the negative electrode, glass fiber as the separator, 2M zinc sulfate as the electrolyte, a pole piece loaded with dextran 70 binder as the positive electrode, and a 2025 model positive and negative battery shell to assemble a button-type zinc-iodine full battery.

[0062] Example 7

[0063] First, 100 mg of commercial activated carbon and iodine were added separately and mixed, and calcined at a temperature of 120° C. for 6 h to prepare an iodine-loaded carbon material.

[0064] Secondly, 35 mg of iodine-loaded carbon material, 10 mg of Ketjen black, and 5 mg of locust bean gum were uniformly mixed, and 5 mL of water was added as a solvent to grind into a slurry. The grinding time was 30 min.

[0065] The slurry was then evenly coated on a 12 mm round stainless steel mesh and dried in a vacuum drying oven at 40°C for 6 h to prepare a positive electrode sheet. The iodine active material loading in the positive electrode sheet was 1.5 mg cm -2 .

[0066] Finally, a 12mm round zinc sheet was used as the negative electrode, glass fiber as the separator, 2M zinc sulfate as the electrolyte, a pole piece loaded with locust bean gum binder as the positive electrode, and a 2025 model positive and negative battery shell were assembled into a button-type zinc-iodine full battery.

[0067] Example 8

[0068] First, 100 mg of commercial activated carbon and iodine were added separately and mixed, and calcined at a temperature of 120° C. for 6 h to prepare an iodine-loaded carbon material.

[0069] Secondly, 35 mg of iodine-loaded carbon material, 10 mg of Ketjen black, and 5 mg of konjac gum were uniformly mixed, and 5 mL of water was added as a solvent to grind into a slurry. The grinding time was 30 minutes.

[0070] The slurry was then evenly coated on a 12 mm round stainless steel mesh and dried in a vacuum drying oven at 40°C for 6 h to prepare a positive electrode sheet. The iodine active material loading in the positive electrode sheet was 1.5 mg cm -2 .

[0071] Finally, a 12mm round zinc sheet was used as the negative electrode, glass fiber as the separator, 2M zinc sulfate as the electrolyte, the electrode sheet containing konjac gum binder as the positive electrode, and 2025 model positive and negative battery shells were assembled into a button-type zinc-iodine full battery.

[0072] Comparative Example 1

[0073] First, 100 mg of commercial activated carbon and iodine were added separately and mixed, and calcined at a temperature of 120° C. for 6 h to prepare an iodine-loaded carbon material.

[0074] Next, 35 mg of iodine-loaded carbon material, 10 mg of Ketjen black, and 5 mg of PTFE were uniformly mixed, and 5 mL of water was added as a solvent to grind the mixture into a slurry. The grinding time was 30 min.

[0075] The slurry was then evenly coated on a 12 mm round stainless steel mesh and dried in a vacuum drying oven at 40°C for 6 h to prepare a positive electrode sheet. The iodine active material loading in the positive electrode sheet was 1.5 mg cm -2 .

[0076] Finally, a 12mm round zinc sheet was used as the negative electrode, glass fiber as the separator, 2M zinc sulfate as the electrolyte, a pole piece loaded with PTFE binder as the positive electrode, and a 2025 model positive and negative battery shell were assembled into a button-type zinc-iodine full battery.

[0077] Test Case

[0078] The cycle stability test was carried out at a current density of 1A / g, and the performance comparison was Figure 1 As shown in Figure 2, the battery using guar gum binder has a specific capacity of 136 mAh / g and a capacity retention rate of 80% after 10,000 cycles. In contrast, the battery using PTFE binder has a specific capacity decay of 88 mAh / g after 4,349 cycles, and a capacity retention rate of only 50%.

[0079] The rate performance test was carried out at current densities of 0.1, 0.2, 0.3, 0.5, 1, 2, and 3 A / g. The performance comparison was as follows: Figure 2 As shown in the figure, the rate performance of the battery using guar gum binder is better than that of the battery using PTFE binder.

[0080] The performance of the batteries using guar gum binder and PTFE binder was compared after charging and then standing for 48 hours. Figure 3 As shown in the figure, the capacity retention rate of the battery using guar gum binder after 48 hours of standing is 92.58%, while that of the battery using PTFE binder is only 82.23%, indicating that the battery using guar gum binder has better anti-self-discharge performance.

[0081] The guar gum powder in Example 1 and the PTFE powder in the comparative example were added to the 100-fold diluted I3 - The solution was allowed to stand for three days, and the supernatant was taken to measure the UV spectrum. The I3 - The concentration was lower than that of control group ( Figure 4 ).

[0082] I3 was added dropwise to the guar gum powder in Example 1 and the PTFE powder in Comparative Example 1. - The solution was tested by Raman spectroscopy, and the adsorbed I3 in Example 1 of the experimental group - The concentration was higher than that of control group 1 ( Figure 5 ).

[0083] The guar gum powder in Example 1 was added dropwise to I3 - The solution was tested by X-ray photoelectron spectroscopy, and I3 adsorption was detected. - The binding energy of the N and O functional groups of guar gum shifted to a more negative direction before and after the reaction, indicating that guar gum has a chemical adsorption effect on polyiodide ( Figure 6 ).

[0084] The batteries using guar gum binder and PTFE binder after 50 cycles at a current density of 1 A / g were disassembled and the zinc negative electrode was characterized by SEM. The surface of the zinc negative electrode in the experimental group Example 1 was relatively smooth, while the zinc negative electrode in the control group had a certain degree of corrosion due to the multi-iodide shuttle effect ( Figure 7 ).

[0085] A cycle stability test was conducted at a current density of 5 A / g. The battery using sodium alginate binder had a specific capacity of 86.3 mAh / g and a capacity retention rate of 80% after 40,000 cycles.

[0086] The cycle stability test was carried out at a current density of 0.3 A / g, and the battery using carboxymethyl chitosan binder had a specific capacity of 113.5 mAh / g after 1811 cycles.

[0087] The cycle stability test was carried out at a current density of 0.3 A / g, and the battery using sodium hyaluronate binder had a specific capacity of 103.6 mAh / g after 1985 cycles.

[0088] The cycle stability test was carried out at a current density of 0.3 A / g, and the battery using hydroxypropyl methylcellulose binder had a specific capacity of 107.4 mAh / g after 851 cycles.

[0089] The cycle stability test was carried out at a current density of 0.3 A / g. The battery using dextran 70 binder had a specific capacity of 104.3 mAh / g after 1563 cycles.

[0090] A cycle stability test was conducted at a current density of 1 A / g. The battery using locust bean gum binder had a specific capacity of 135 mAh / g after 10,000 cycles, and the capacity retention rate was 87%.

[0091] Carry out cycle stability test under the current density of 1A / g, the battery adopting konjac gum binder has the specific capacity of 117mAh / g after 10000 cycles, and the capacity retention rate is 84%.Table 1 is the comparison of the sample of the iodine-carrying positive electrode prepared by the above-mentioned embodiment and the preparation of the above-mentioned comparative example in terms of cycle performance.

[0092] Table 1

[0093] sample Current density (A / g) Number of cycles Specific capacity (mAh / g) Example 1 1 10000 136 Example 2 5 40000 86.3 Example 3 0.3 1811 113.5 Example 4 0.3 1985 103.6 Example 5 0.3 851 107.4 Example 6 0.3 1563 104.3 Example 7 1 10000 135 Example 8 1 10000 117 Comparative Example 1 1 4349 88

[0094] It can be seen from the data in Table 1 that the long cycle performance at different current densities was tested for Examples 1-8. The iodine-loaded positive electrode of the zinc-iodine battery using a polysaccharide binder has good long cycle performance in the current density range of 0.3-5 A / g, while the iodine-loaded positive electrode using a PTFE binder has a specific capacity decay to 88 mAh / g after only 4349 cycles at a current density of 1 A / g, and fails after 4500 cycles.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing an iodine-loaded positive electrode for a zinc-iodine battery, characterized in that: The following steps are involved: The iodine-loaded carbon material, conductive carbon black, polysaccharide binder and deionized water are mixed in proportion and then ground into slurry, the slurry is evenly coated on a current collector, and the iodine-loaded positive electrode of the zinc-iodine battery is obtained after drying.

2. The method for preparing an iodine-carrying positive electrode for zinc-iodine batteries according to claim 1, wherein The polysaccharide binder is selected from at least one of sodium alginate, carboxymethyl chitosan, sodium hyaluronate, hydroxypropyl methylcellulose, dextran 70, guar gum, locust bean gum, and konjac gum.

3. The method for preparing an iodine-carrying positive electrode for zinc-iodine batteries according to claim 1, wherein The mass ratio of the iodine-loaded carbon material, the conductive carbon black and the polysaccharide binder is 7:2:

1.

4. The method for preparing an iodine-carrying positive electrode for zinc-iodine batteries according to claim 1, wherein The grinding time is 30-60 min.

5. The method for preparing an iodine-carrying positive electrode for zinc-iodine batteries according to claim 1, wherein: The iodine-loaded carbon material is a commercial activated carbon-iodine composite material, and its specific preparation process is as follows: Commercial activated carbon and elemental iodine were heated at 120°C for 6 hours to prepare iodine-loaded carbon material.

6. The method for preparing an iodine-carrying positive electrode for zinc-iodine batteries according to claim 1, wherein: The conductive carbon black is Ketjen black; the current collector is a circular stainless steel mesh with a diameter of 12 mm.

7. The method for preparing an iodine-carrying positive electrode for zinc-iodine batteries according to claim 1, wherein: The drying temperature is 40-60° C., and the drying time is 6-8 hours.

8. The method for preparing an iodine-carrying positive electrode for zinc-iodine batteries according to claim 1, wherein: The loading amount of iodine active substance is 1-2 mg cm -2 .

9. An iodine-loaded positive electrode for a zinc-iodine battery, characterized in that: An iodine-loaded positive electrode for a zinc-iodine battery prepared by the method according to any one of claims 1 to 8.

10. A zinc-iodine battery comprising the iodine-carrying positive electrode for a zinc-iodine battery according to claim 9.

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