Preparation method of iodine positive electrode protection material in battery and application of iodine positive electrode protection material in zinc-iodine battery

Abstract

The invention belongs to the technical field of batteries, and particularly relates to a preparation method of an iodine positive electrode protection material in a battery and application of the iodine positive electrode protection material in a zinc-iodine battery. According to the invention, high amylose is used as a raw material, and the recombinant high amylose is prepared through the processes of dissolution, alcohol precipitation, drying and the like and is used as a positive electrode protection material of a battery. After being mixed with iodine, sodium carboxymethyl cellulose, ketjen black and the like, the zinc-iodine compound can be prepared into a positive plate of a battery, and the positive plate and other battery parts are assembled into a zinc-iodine rechargeable battery, so that the shuttle effect of multiple iodine ions when iodine is used as the positive electrode of the battery is inhibited. According to the zinc-iodine battery prepared by the method disclosed by the invention, the charge-discharge cycle stability and the rate stability are remarkably improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of batteries, and particularly relates to a preparation method of an iodine positive electrode protection material in a battery and application of the iodine positive electrode protection material in a zinc-iodine battery. BACKGROUND

[0002] With the continuous rise of global energy demand, developing efficient and environmentally friendly energy storage technology is the current research hotspot. Among many batteries, aqueous zinc-iodine batteries have attracted widespread attention of researchers due to their low cost and good compatibility of electrode materials with aqueous electrolytes. However, the iodine in the positive electrode of the battery has a multi-iodine ion shuttle effect, that is, during the charging and discharging process, multi-iodine ions (such as I3 - and I5 - ) are easily dissolved in the aqueous electrolyte, migrate to the zinc surface through the separator, and react irreversibly with zinc, resulting in a shortened cycle life and decreased performance of the battery. Therefore, a protection material needs to be added to the positive electrode of the battery to eliminate this effect.

[0003] Among many iodine positive electrode protection materials, starch stands out due to its low price, renewability, and environmental friendliness. Previous studies have found that using starch as a positive electrode protection material for iodine can significantly inhibit the shuttle of multi-iodine compounds and improve the charge-discharge cycle stability and rate stability of zinc-iodine batteries.

[0004] On the other hand, there are two types of starch molecules in natural starch granules: amylopectin and amylose. Amylopectin has short chains, and the degree of polymerization of glucan is below 20. Amylose has long chains, and the degree of polymerization of glucan can reach 40-100. The adsorption capacity of starch for multi-iodine ions is closely related to the chain length. In theory, the more amylose content in starch, the stronger the inhibitory capacity of the positive electrode protection material for iodine ion shuttle effect, and the more significant the improvement of battery performance. However, natural high amylose starch granules have a dense structure, with starch chains tightly entangled and strong hydrogen bonding forces, forming agglomerates, making it difficult to completely disperse into starch chains and fully utilize the adsorption performance of iodine ions. Currently, there is no report on the use of high amylose starch as a positive electrode protection material for iodine in batteries.

[0005] In summary, using high amylose starch as a raw material to prepare a positive electrode protection material for iodine will help improve the performance of zinc-iodine rechargeable batteries and expand their application in battery energy storage. However, how to improve the performance of high amylose starch to prepare a positive electrode protection material for iodine to improve the performance of zinc-iodine batteries is a technical problem that needs to be solved. SUMMARY

[0006] In order to overcome the above-mentioned deficiencies of the prior art, the present application provides a preparation method of an iodine positive electrode protection material in a battery and application thereof in a zinc-iodine battery. The present application uses high amylose starch to prepare an iodine positive electrode protection material for a battery. The starch-based iodine positive electrode protection material prepared by the method of the present application can inhibit the shuttle effect of iodine ions when iodine is used as the positive electrode of the battery, and significantly improve the charge-discharge cycle stability and rate stability of the battery.

[0007] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0008] The first aspect of the present application provides a preparation method of an iodine positive electrode protection material in a battery, which comprises the following steps:

[0009] (1) adding high amylose starch into a potassium iodide solution, heating and stirring to obtain a starch solution;

[0010] (2) adding distilled water into the starch solution, and then adding ethanol after cooling to room temperature and continuously stirring until white flocculation appears;

[0011] (3) collecting the white precipitate by centrifugation, washing with distilled water, freeze-drying, grinding into powder, and sieving to obtain reconstituted high amylose starch, which is the iodine positive electrode protection material.

[0012] Further, in step (1), the high amylose starch refers to natural starch with a content of amylose in starch granules exceeding 50%.

[0013] Further, in step (1), the concentration of the potassium iodide solution is ≧4 mol / L, and the mass ratio of the high amylose starch to the potassium iodide solution is ≦1:5.

[0014] Further, in step (1), the heating temperature is ≧85℃, and the heating time is ≧45 min.

[0015] Further, in step (2), the added amount of the distilled water is ≧2 times the volume of the starch solution, and the added amount of the ethanol is ≧3 times the volume of the starch solution.

[0016] The second aspect of the present application provides an iodine positive electrode protection material prepared by the above-mentioned preparation method.

[0017] The third aspect of the present application provides application of the above-mentioned iodine positive electrode protection material in a zinc-iodine battery, and the application method comprises the following steps:

[0018] Step S1: mixing the iodine positive electrode protection material with iodine, sealing and heating to prepare a starch / iodine mixture;

[0019] Step S2: mixing and grinding the starch / iodine mixture with sodium carboxymethyl cellulose and Ketjen black, and then adding distilled water to prepare a slurry;

[0020] Step S3: coating the slurry on the carbon cloth, vacuum drying, cutting to obtain the positive electrode sheet of the battery;

[0021] Step S4: assembling in the order of negative electrode shell, zinc sheet, separator, electrolyte, the positive electrode sheet prepared in step S3, gasket, spring, positive electrode shell, and sealing with a sheet presser to obtain the zinc-iodine battery.

[0022] Further, in step S1, the mass ratio of iodine to the iodine positive electrode protection material is >= 2:1.

[0023] Further, in step S2, the total mass ratio of the starch / iodine mixture to carboxymethyl cellulose sodium and Ketjen black is <= 8:2, and the mass ratio of carboxymethyl cellulose sodium to Ketjen black is <= 1:1.

[0024] Further, in step S3, the temperature of the vacuum drying is >= 45 DEG C, and the time is >= 4 hours.

[0025] In order to solve the problem of poor charge-discharge stability and rate stability of the battery caused by the shuttle of polyiodide when iodine is used as the positive electrode of the battery, an iodine positive electrode maintenance material needs to be added. The previous people use activated carbon and ordinary starch as the positive electrode protection material. The activated carbon mainly relies on its porous structure to physically adsorb iodine, and the adsorption capacity is weak. Although the ordinary starch can allow iodine ions to enter the starch chain cavity to form a starch-iodine compound, the content of branched starch in the ordinary starch is more than 70%, and the molecular chain length is short, and the adsorption amount and adsorption force of the iodine ions are limited, and the improvement degree of the performance of the zinc-iodine battery is also limited.

[0026] Since the adsorption capacity, adsorption amount and adsorption stability of the starch chain to the polyiodide are closely related to the chain length, theoretically, the use of high amylose starch as the positive electrode protection material of iodine can further improve the performance of the battery. However, in the natural high amylose starch particles, the molecular chains are tightly wound, the hydrogen bond force is strong, and the structure is dense, and it is difficult to completely disperse into the state of starch chains.

[0027] Therefore, the application uses a high-concentration potassium iodide solution to deconstruct the natural high amylose starch particles, and after dissolution, alcohol precipitation and drying, a reorganized high amylose starch with fully dispersed starch chains is obtained. The reorganized high amylose starch is used together with iodine, carboxymethyl cellulose sodium, Ketjen black and other substances to prepare the positive electrode sheet of the zinc-iodine battery.

[0028] By this method, the transmembrane migration of polyiodide in the battery is significantly inhibited, and the charge-discharge stability and rate stability of the zinc-iodine battery are improved.

[0029] Compared with the prior art, the application has the following beneficial effects:

[0030] The application discloses a preparation method of an iodine positive electrode protection material in a battery and application of the iodine positive electrode protection material in a zinc-iodine battery.

[0031] Specifically, the application has the following advantages:

[0032] (1) The zinc-iodine rechargeable battery prepared by using the renewable and green starch as the positive electrode protection material meets the green and environment-friendly characteristics of the current sustainable development energy strategy,

[0033] (2) The positive electrode sheet of the zinc-iodine battery is prepared by using the recombined high straight-chain starch and iodine, the shuttle effect of polyiodide ions is inhibited, the charge-discharge cycle stability and the rate cycle stability of the zinc-iodine battery can be significantly improved, and the battery performance is improved. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 Results of the charge-discharge stability test of the zinc-iodine batteries prepared for example 1, example 2, example 3 and comparative example 1. DETAILED DESCRIPTION

[0035] The specific embodiments of the application are further described below. It should be noted that the description of these embodiments is used to help understand the application, but does not constitute a limitation on the application. In addition, the technical features involved in each embodiment of the application described below can be combined with each other as long as they do not conflict with each other.

[0036] The experimental methods in the following examples are all conventional methods unless otherwise specified. The test materials used in the following examples are all commercially available unless otherwise specified. The battery shell assemblies in the following examples and comparative examples are purchased from Shenzhen Xinweier Electronics Co., Ltd., the zinc sheets are purchased from Hefei Haochen Metal Material Trading Co., Ltd., and the electrolyte is a 1M zinc sulfate solution.

[0037] Example 1: A preparation method of an iodine positive electrode protection material in a battery and application of the iodine positive electrode protection material in a zinc-iodine battery

[0038] (1) 100 mL of 4 mol / L potassium iodide solution is taken, 20 g of high straight-chain starch G50 (straight-chain starch content is 55%) is added, uniform stirring is carried out, heating and stirring are carried out at 85 DEG C for 45 minutes, and a starch solution is obtained.

[0039] (2) 200 mL of distilled water is added to the starch solution of step (1), and after cooling to room temperature, 300 mL of ethanol is gradually added and continuously stirred until white flocculation appears.

[0040] (3) Centrifuge the starch emulsion obtained in step (2) at a speed of 4000 r / min for 5 minutes, collect the precipitate, wash it 3 times with distilled water, freeze dry it in a freeze dryer, grind it into powder and pass it through a 100-mesh sieve to obtain recombinant high amylose starch.

[0041] (4) Take 0.2g of the recombinant high amylose from step (3), mix it with 0.4g of iodine, place it in a stoppered glass bottle, heat it at 120°C for 4 hours, then remove the stopper from the glass bottle and cool it to room temperature to obtain a starch / iodine mixture.

[0042] (5) Mix the starch / iodine mixture in step (4) with carboxymethyl cellulose and Ketjen black in a mass ratio of 8:1:1, grind for 15 minutes, add distilled water to make a slurry, coat it onto carbon cloth, and then vacuum dry at 45°C for 4 hours to obtain the positive electrode current collector.

[0043] (6) Cut the dried positive electrode current collector from step (5) into round pieces to obtain the positive electrode sheet of the battery. Assemble the negative electrode shell, zinc sheet, separator, electrolyte (70μL), positive electrode sheet, gasket, spring sheet, and positive electrode shell into a button cell in that order. Then seal it with a tablet press to obtain a zinc-iodine battery.

[0044] Example 2: A method for preparing an iodine positive electrode protective material in a battery and its application in a zinc-iodine battery.

[0045] (1) Take 100 mL of 4 mol / L potassium iodide solution, add 15 g of high amylose G70 (amylose content is 68%), stir evenly, heat and stir at 85℃ for 45 minutes to obtain starch solution.

[0046] (2) Add 200 mL of distilled water to the starch solution in step (1), cool to room temperature, and then gradually add 300 mL of ethanol while stirring continuously until white flocculation occurs.

[0047] (3) Centrifuge the starch emulsion obtained in step (2) at a speed of 4000 r / min for 5 minutes, collect the precipitate, wash it 3 times with distilled water, freeze dry it in a freeze dryer, grind it into powder and pass it through a 100-mesh sieve to obtain recombinant high amylose starch.

[0048] (4) Take 0.2g of the recombinant high amylose from step (3), mix it with 0.4g of iodine, place it in a stoppered glass bottle, heat it at 120°C for 4 hours, then remove the stopper from the glass bottle and cool it to room temperature to obtain a starch / iodine mixture.

[0049] (5) Mix the starch / iodine mixture in step (4) with carboxymethyl cellulose and Ketjen black in a mass ratio of 8:1:1, grind for 15 minutes, add distilled water to make a slurry, coat it onto carbon cloth, and then vacuum dry at 45°C for 4 hours to obtain the positive electrode current collector.

[0050] (6) Cut the dried positive electrode current collector from step (5) into round pieces to obtain the positive electrode sheet of the battery. Assemble the negative electrode shell, zinc sheet, separator, electrolyte (70μL), positive electrode sheet, gasket, spring sheet, and positive electrode shell into a button cell in that order. Then seal it with a tablet press to obtain a zinc-iodine battery.

[0051] Example 3: A method for preparing an iodine positive electrode protective material in a battery and its application in a zinc-iodine battery.

[0052] (1) Take 100 mL of 4.5 mol / L potassium iodide solution, add 15 g of high amylose G70 (amylose content is 68%), stir evenly, heat and stir at 85℃ for 45 minutes to obtain starch solution.

[0053] (2) Add 250 mL of distilled water to the starch solution in step (1), cool to room temperature, and then gradually add 350 mL of ethanol while stirring continuously until white flocculation occurs.

[0054] (3) Centrifuge the starch emulsion obtained in step (2) at a speed of 4000 r / min for 5 minutes, collect the precipitate, wash it 3 times with distilled water, freeze dry it in a freeze dryer, grind it into powder and pass it through a 100-mesh sieve to obtain recombinant high amylose starch.

[0055] (4) Take 0.2g of the recombinant high amylose from step (3), mix it with 1.0g of iodine, place it in a stoppered glass bottle, heat it at 120°C for 4 hours, then remove the stopper from the glass bottle and cool it to room temperature to obtain a starch / iodine mixture.

[0056] (5) Mix the starch / iodine mixture in step (4) with carboxymethyl cellulose and Ketjen black in a mass ratio of 7:1.5:1.5, grind for 15 minutes, add water to make a slurry, coat it onto carbon cloth, and then vacuum dry it at 45°C for 4 hours to obtain the positive electrode current collector.

[0057] (6) Cut the dried positive electrode current collector from step (5) into round pieces to obtain the positive electrode sheet of the battery. Assemble the negative electrode shell, zinc sheet, separator, electrolyte (70μL), positive electrode sheet, gasket, spring sheet, and positive electrode shell into a button cell in that order. Then seal it with a tablet press to obtain a zinc-iodine battery.

[0058] Comparative Example 1

[0059] Steps (2)-(6) are the same as the corresponding steps in Example 2, except that in step (1), high amylose G70 (amylose content of 68%) is replaced with ordinary starch.

[0060] Test Example 1

[0061] The zinc-iodine batteries prepared in Examples 1, 2, 3, and Comparative Example 1 were subjected to charge-discharge stability tests. Battery performance was tested at room temperature using a Newway battery testing system, with a cutoff voltage range of 0.5-1.6V, including energy storage performance parameters such as specific capacity and cycle stability. The test results are as follows: Figure 1 As shown, a comprehensive comparison of the results of Examples 1, 2, and 3, as well as Comparative Example 1, reveals that when high-amylose starch is used to prepare the battery iodine cathode protection material and applied to a zinc-iodine rechargeable battery system, the long starch chains exhibit a strong adsorption capacity for polyiodide ions, effectively suppressing the shuttle effect of iodide ions. This mechanism significantly improves the charge-discharge stability and rate stability of the zinc-iodine battery, providing strong support for battery performance optimization. Furthermore, starch is not only inexpensive but also environmentally friendly, making it a high-quality biomass material. Based on these characteristics, this invention opens up a new path for the development of green and safe energy storage batteries, possessing extremely broad application prospects in the future energy storage field.

[0062] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for preparing an iodine positive electrode protective material in a battery, characterized in that, The preparation method includes the following steps: (1) Add high-amylose starch to potassium iodide solution, heat and stir to obtain starch solution; (2) Add distilled water to the starch solution, cool to room temperature, then add ethanol and stir continuously until white flocculation occurs; (3) Centrifuge to collect the white precipitate, wash with distilled water, freeze dry, grind into powder, and sieve to obtain recombinant high amylose starch, which is the iodine positive electrode protection material.

2. The method for preparing an iodine positive electrode protective material in a battery according to claim 1, characterized in that, In step (1), the high amylose refers to natural starch with an amylose content of more than 50% in starch granules.

3. The method for preparing an iodine positive electrode protective material in a battery according to claim 1, characterized in that, In step (1), the concentration of the potassium iodide solution is ≥4 mol / L, and the mass ratio of the high amylose to the potassium iodide solution is ≤1:

5.

4. The method for preparing an iodine positive electrode protective material in a battery according to claim 1, characterized in that, In step (1), the heating temperature is ≥85℃ and the time is ≥45min.

5. The method for preparing an iodine positive electrode protective material in a battery according to claim 1, characterized in that, In step (2), the amount of distilled water added is ≥ 2 times the volume of the starch solution, and the amount of ethanol added is ≥ 3 times the volume of the starch solution.

6. An iodine cathode protective material prepared by the preparation method according to any one of claims 1-6.

7. The application of the iodine positive electrode protection material as described in claim 7 in a zinc-iodine battery, characterized in that, The method of application includes the following steps: Step S1: Mix the iodine positive electrode protective material with iodine, seal and heat to obtain a starch / iodine mixture; Step S2: Mix and grind the starch / iodine mixture with sodium carboxymethyl cellulose and Ketjen black, then add distilled water to make a slurry; Step S3: Apply the slurry onto the carbon cloth, vacuum dry it, and cut it to obtain the positive electrode sheet of the battery; Step S4: Assemble the negative electrode shell, zinc sheet, separator, electrolyte, positive electrode sheet prepared in step S3, gasket, spring sheet, and positive electrode shell in that order, and then seal them with a tablet press to obtain the zinc-iodine battery.

8. The application of the iodine positive electrode protective material according to claim 7 in a zinc-iodine battery, characterized in that, In step S1, the mass ratio of iodine to iodine positive electrode protection material is ≥2:

1.

9. The application of the iodine positive electrode protective material according to claim 7 in a zinc-iodine battery, characterized in that, In step S2, the mass ratio of the starch / iodine mixture to the total mass of sodium carboxymethyl cellulose and Ketjen black is ≤8:2, and the mass ratio of sodium carboxymethyl cellulose and Ketjen black is ≤1:

1.

10. The application of the iodine positive electrode protective material according to claim 7 in a zinc-iodine battery, characterized in that, In step S3, the vacuum drying temperature is ≥45℃ and the time is ≥4 hours.

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