An iodine cathode interface conductive polymer slurry, an iodine cathode and its preparation method, and their application in I - / I2 / I + Applications in positive-valence zinc-iodine batteries

Abstract

This invention discloses an iodine cathode interface conductive polymer slurry, an iodine cathode and its preparation method, and its application in I... ‑ / I2 / I + In the application of positive-valence zinc-iodine batteries, the conductive polymer slurry at the iodine cathode interface is formed by combining an aqueous adhesive and a PEDOT:PSS dispersion. This conductive polymer slurry is uniformly coated onto the surface of the iodine cathode, and after drying, a dense conductive polymer film is formed on the iodine cathode surface. The PEDOT:PSS film of this invention can inhibit polyiodine ion shuttle and I₂ from both physical barrier and chemical adsorption perspectives. + Hydrolysis; when the iodine cathode loading is 10 mg cm⁻¹ ‑2 At that time, the discharge plateau of the zinc-iodine battery was 1.6 V (I 0 / I + ) and 1.2 V(I ‑ / I 0 Its capacity retention rate after 3500 stable cycles is over 91%, effectively improving the performance of the iodine cathode and enhancing the overall performance of the battery; it belongs to the field of battery technology.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to an iodine cathode interface conductive polymer slurry and an iodine cathode. This invention also relates to a method for preparing the iodine cathode conductive polymer film and its application in positive-valence zinc-iodine batteries. Background Technology

[0002] With the large-scale grid connection of renewable energy and the rapid development of smart grids, the development of large-scale, low-cost, highly safe, and long-life electrochemical energy storage systems has become an urgent need. Among numerous energy storage technologies, aqueous zinc-based batteries stand out due to the high theoretical capacity (820 mAh g⁻¹) of the zinc anode. -1 Zinc-iodine batteries are considered a highly promising candidate due to their outstanding advantages, including low redox potential (-0.76 V vs. SHE), abundant reserves, environmental friendliness, and inherent safety of aqueous electrolytes. The four-electron zinc-iodine battery represents a cutting-edge research direction for next-generation high-energy-density aqueous batteries. Its core principle transcends the single I₂ / I₂ principle found in traditional iodine batteries. - Redox pairs aim to achieve a two-electron transfer reaction for each iodine atom by activating a higher oxidation state of iodine. The specific reaction pathway is generally considered to involve iodides (I₂O₃). - ), zero-valent iodine (I 0 The conversion between iodine (I⁺) and monovalent iodine (I⁺). Based on I⁺ - / I2 / I + The theoretical specific capacity of iodine in a four-electron positive conversion zinc-iodine battery can reach approximately 422 mAh g. -1 It is a traditional single-electron reaction (211 mAh g). -1 This enormous capacity potential makes the four-electron zinc-iodine battery stand out among new energy storage technologies that pursue ultimate energy density.

[0003] However, this battery also faces challenges such as the polyiodide shuttle effect, slow iodine species conversion kinetics, and zinc dendrite growth. The polyiodide shuttle effect leads to a decline in battery performance, while the slow iodine species conversion kinetics affects the battery's charge and discharge efficiency. To address these issues, researchers have employed catalyst and host designs to improve the performance of the iodine cathode, or adopted various protection strategies to stabilize the zinc metal anode. Furthermore, novel electrolyte designs have been proposed to simultaneously stabilize the zinc anode and accelerate the redox kinetics of the iodine cathode.

[0004] To suppress the shuttle effect of polyiodides, researchers have explored various methods. For example, porous carbon materials (such as activated carbon, mesoporous carbon, and graphene) are used to physically confine iodine, utilizing their large specific surface area to adsorb iodine and polyiodide ions to alleviate the shuttle effect. However, the physical adsorption force between carbon materials and nonpolar iodine molecules is weak, and under long-term cycling and high-concentration conditions, it cannot effectively bind polar polyiodide ions, resulting in limited confinement. In addition, researchers have tried using novel porous materials such as metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), but their high cost and poor conductivity remain significant problems. Another strategy is to introduce functional membranes or intermediate layers, such as designing positively charged membranes to electrostatically repel polyiodide ions. However, this method increases the complexity of the battery structure and manufacturing cost, and may sacrifice ionic conductivity. Furthermore, electrolyte additives are a simple and effective strategy. By changing the composition, concentration, and properties of the electrolyte, the shuttle effect can also be reduced and cycle stability improved. However, mature electrolyte formulations and suitable electrolyte additive compatibility rules have not yet been developed. Summary of the Invention

[0005] To address the shortcomings and deficiencies of existing zinc-iodine technologies, this invention aims to provide a method that improves the performance of iodine cathodes and enhances the overall performance of batteries by constructing a PEDOT:PSS conductive polymer film on the iodine cathode.

[0006] Another object of the present invention is to provide a method for preparing an iodine cathode based on a PEDOT:PSS conductive polymer film.

[0007] Another object of the present invention is to provide the above-mentioned iodine cathode for the preparation of PEDOT:PSS films in I - / I 0 / I + Application in four-electron positive-valence zinc-iodine batteries. In a zinc-iodine battery with an iodine loading of 10 mg cm⁻¹. -2 Under these conditions, the zinc-iodine battery not only exhibits a voltage of 1.6V (I 0 / I + ) and 1.2 V (I - / I 0 It features a dual discharge platform and maintains a high capacity retention of 91% after 3500 cycles.

[0008] Therefore, the first technical solution provided by this invention is as follows:

[0009] An iodine cathode interface conductive polymer slurry is formed by combining an aqueous adhesive and a PEDOT:PSS dispersion to form a conductive polymer slurry.

[0010] Furthermore, in the aforementioned iodine cathode interface conductive polymer slurry, the ratio of the aqueous adhesive to PEDOT:PSS is 0.00375g:0.8-1.2mL.

[0011] Furthermore, in the aforementioned iodine cathode interface conductive polymer slurry, the PEDOT:PSS dispersion is composed of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid in a mass ratio of 1:6.

[0012] Furthermore, in the aforementioned iodine cathode interface conductive polymer slurry, the aqueous adhesive is sodium carboxymethyl cellulose.

[0013] The second technical solution provided by the present invention is an iodine positive electrode based on a PEDOT:PSS conductive polymer film, comprising an iodine / carbon electrode sheet, wherein the surface of the iodine / carbon electrode sheet is coated with the above-mentioned iodine electrode sheet interface conductive polymer slurry.

[0014] The present invention also provides a method for preparing the above-mentioned iodine cathode based on PEDOT:PSS conductive polymer film, comprising the following steps in sequence:

[0015] S1: Add the aqueous adhesive to the PEDOT:PSS dispersion and stir at room temperature to obtain a conductive polymer slurry;

[0016] S2: The conductive polymer slurry prepared in step S1 is uniformly drop-coated onto the surface of the iodine / carbon electrode. After drying, a dense thin film is formed on the surface of the iodine / carbon electrode, thus obtaining an iodine cathode based on the PEDOT:PSS conductive polymer film.

[0017] Furthermore, the stirring time in step S1 of the above-mentioned method for preparing the iodine cathode based on the PEDOT:PSS conductive polymer film is 2-5 hours.

[0018] Furthermore, the drying process described in step S2 of the above-mentioned method for preparing the iodine cathode based on the PEDOT:PSS conductive polymer film is performed by drying in a 60°C forced-air drying oven for 30 minutes.

[0019] The present invention also provides an I - / I2 / I + A zinc-iodine battery with four-electron positive conversion includes a negative electrode, an electrolyte, a separator, and a positive electrode, wherein the positive electrode is the aforementioned iodine positive electrode based on a PEDOT:PSS conductive polymer film.

[0020] Furthermore, the aforementioned I - / I2 / I + The zinc-iodine battery with four positive electron conversion has a zinc metal sheet as the negative electrode, a Whatman glass fiber separator, and a brine-containing electrolyte.

[0021] More preferably, the brine-containing electrolyte is 2 mol / L ZnCl2.

[0022] The PEDOT:PSS of this invention, as a conductive polymer film at the positive electrode interface, simultaneously meets the following three requirements: ① Suppressing the shuttle effect of polyiodides: The S and O functional groups in PEDOT:PSS can form strong interactions with iodine species, effectively anchoring iodine and reducing the dissolution and shuttle of soluble polyiodide intermediates, thereby alleviating the problems of self-discharge and rapid capacity decay. ② Improving conductivity and charge transfer: PEDOT:PSS has high conductivity, forming a continuous conductive network on the surface of the iodine positive electrode, reducing the interfacial charge transfer impedance, and improving the reversibility of the redox reaction of iodine and its rate performance. ③ Enhancing cycle stability: The mesoporous PEDOT:PSS coating layer can buffer the volume change of iodine during charge and discharge, maintain the integrity of the electrode structure, and enable the battery to maintain a low capacity decay rate (approximately 0.0029% / cycle) even after a high number of cycles (e.g., 3500 cycles).

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The mechanism of action of the conductive polymer film at the positive electrode interface of the present invention mainly focuses on physical encapsulation and chemical adsorption, which can synergistically suppress polyiodide shuttle, enhance conductivity and structural stability, and significantly improve the specific capacity, cycle life and rate performance of the four-electron zinc-iodine battery.

[0025] 2. This invention applies a conductive polymer PEDOT:PSS film based on an iodine cathode interface to I... - / I2 / I + The four-electron positive-valence conversion reaction zinc-iodine battery not only exhibits a 1.6 V (I 0 / I + ) and 1.2 V (I - / I 0 It features a dual discharge platform and maintains a high capacity retention rate of over 91% after 3500 cycles.

[0026] 3. The iodine cathode interface conductive polymer of the present invention has a lower cost compared with high-concentration salt / deep eutectic electrolyte. Attached Figure Description

[0027] Figure 1 The molecular structural formula of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS) of the present invention is as follows.

[0028] Figure 2 To demonstrate the rate performance of zinc-iodine batteries in Examples 1-2.

[0029] Figure 3 The charge-discharge curves of the zinc-iodine batteries used in Examples 1-2 are shown.

[0030] Figure 4 For example 1-4, zinc-iodine full cells were used in 2 A g. -1 The loop performance is as follows.

[0031] Figure 5 For example 1-2, zinc-iodine batteries were used at 0.5 A g. -1 The loop performance is as follows. Attached Figure Description Detailed Implementation

[0037] The present invention will be further described below with reference to specific embodiments, but these should not be construed as limiting the invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the technical field.

[0038] The I2@AC electrode used in the following embodiments and comparative examples was prepared through the following steps:

[0039] 1) Activated carbon (AC) and iodine powder in a mass ratio of 1:1 are thoroughly ground to obtain I2@AC composite material.

[0040] 2) At room temperature, I2@AC, Super P and sodium carboxymethyl cellulose (CMC) binder aqueous solution in a mass ratio of 8:1:1 are ground and mixed thoroughly to form a slurry, which is then coated onto a carbon paper current collector and dried to obtain an iodine / carbon electrode sheet, abbreviated as I2@AC electrode sheet.

[0041] The PEDOT:PSS dispersion used in this application is composed of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid (PEDOT:PSS). The mass ratio of poly(3,4-ethylenedioxythiophene) to polystyrene sulfonic acid is 1:6.

[0042] Example 1

[0043] This embodiment provides an iodine cathode interface conductive polymer slurry: 0.00375 g of sodium carboxymethyl cellulose (CMC) is added to 1 mL of PEDOT-PSS dispersion and stirred at room temperature for 4 h to obtain the conductive polymer slurry.

[0044] Example 2

[0045] This embodiment provides an iodine cathode interface conductive polymer slurry: 0.00375 g of sodium carboxymethyl cellulose (CMC) is added to 0.8 mL of PEDOT-PSS dispersion and stirred at room temperature for 5 h to obtain the conductive polymer slurry.

[0046] Example 3

[0047] This embodiment provides an iodine cathode interface conductive polymer slurry: 0.00375 g of sodium carboxymethyl cellulose (CMC) is added to 1.2 mL of PEDOT-PSS dispersion and stirred at room temperature for 2 h to obtain the conductive polymer slurry.

[0048] Example 4

[0049] This embodiment provides an iodine cathode interface conductive polymer slurry: 0.00375 g of sodium carboxymethyl cellulose (CMC) is added to 1.1 mL of PEDOT-PSS dispersion and stirred at room temperature for 3 h to obtain the conductive polymer slurry.

[0050] Example 5

[0051] This embodiment provides an iodine cathode based on a PEDOT:PSS conductive polymer film. 20 μL of the conductive polymer slurry prepared in Example 1 was pipetted and uniformly dropped onto a surface with an area of ​​1.131 cm². 2 of On the I2@AC electrode, a dense film is formed on the surface of the I2@AC electrode by drying in a 60℃ forced-air drying oven for 30 minutes, thus obtaining the I2@AC@PEDOT:PSS electrode.

[0052] Example 6

[0053] This embodiment provides an iodine cathode based on a PEDOT:PSS conductive polymer film. 15 μL of the conductive polymer slurry prepared in Example 1 was pipetted and uniformly dropped onto a surface with an area of ​​1.131 cm². 2 of On the I2@AC electrode, a dense film is formed on the surface of the I2@AC electrode by drying in a 60℃ forced-air drying oven for 30 minutes, thus obtaining the I2@AC@PEDOT:PSS electrode.

[0054] Example 7

[0055] This embodiment provides an iodine cathode based on a PEDOT:PSS conductive polymer film. 25 μL of the conductive polymer slurry prepared in Example 1 was pipetted and uniformly dropped onto a surface with an area of ​​1.131 cm². 2 of On the I2@AC electrode, a dense film is formed on the surface of the I2@AC electrode by drying in a 60℃ forced-air drying oven for 30 minutes, thus obtaining the I2@AC@PEDOT:PSS electrode.

[0056] Example 8

[0057] This embodiment provides an iodine cathode based on a PEDOT:PSS conductive polymer film. 20 μL of the conductive polymer slurry prepared in Example 2 was pipetted and uniformly dropped onto a surface with an area of ​​1.131 cm². 2 of On the I2@AC electrode, a dense film is formed on the surface of the I2@AC electrode by drying in a 60℃ forced-air drying oven for 30 minutes, thus obtaining the I2@AC@PEDOT:PSS electrode.

[0058] Example 9

[0059] This embodiment provides an iodine cathode based on a PEDOT:PSS conductive polymer film. 20 μL of the conductive polymer slurry prepared in Example 3 was pipetted and uniformly dropped onto a surface with an area of ​​1.131 cm². 2 of On the I2@AC electrode, a dense film is formed on the surface of the I2@AC electrode by drying in a 60℃ forced-air drying oven for 30 minutes, thus obtaining the I2@AC@PEDOT:PSS electrode.

[0060] Example 10

[0061] This embodiment provides an iodine cathode based on a PEDOT:PSS conductive polymer film. 20 μL of the conductive polymer slurry prepared in Example 4 was pipetted and uniformly dropped onto an area of ​​1.131 cm². 2 of On the I2@AC electrode, a dense film is formed on the surface of the I2@AC electrode by drying in a 60℃ forced-air drying oven for 30 minutes, thus obtaining the I2@AC@PEDOT:PSS electrode.

[0062] Examples 1-10: Molecular structural formulas of poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid (PEDOT:PSS) are provided. Figure 1 PEDOT:PSS forms a dense thin film on the surface of the iodine cathode, acting as a highly efficient physical barrier to directly block polyiodide ions (I3). - , I5 - The sulfonic acid groups (-SO3H) in the PEDOT:PSS molecular structure dissolve and migrate from the positive electrode to the zinc negative electrode; these sulfonic acid groups can interact with polyiodides, thereby adsorbing the polyiodides and reducing their free diffusion in the electrolyte.

[0063] Comparative Example 1

[0064] This comparative example uses I2@AC electrode.

[0065] Application Example 1

[0066] This application example provides a zinc-iodine full cell, which is prepared by the following steps:

[0067] 1. Add 0.273 g of zinc chloride to 1 mL of deionized water and stir at room temperature for 2 h to prepare a 2 mol / L zinc chloride solution.

[0068] 2. In Example 5, an I2@AC@PEDOT:PSS electrode was used as the positive electrode, a metal electrode as the negative electrode, Whatman glass fiber as the separator, and 2 mol / L ZnCl2 as the electrolyte to assemble a zinc-iodine full cell.

[0069] Application Example 2

[0070] This application example provides a zinc-iodine full cell, which is prepared by the following steps:

[0071] 1. Add 0.273 g of zinc chloride to 1 mL of deionized water and stir at room temperature for 2 h to prepare a 2 mol / L zinc chloride solution.

[0072] 2. In Example 6, an I2@AC@PEDOT:PSS electrode was used as the positive electrode, a metal electrode as the negative electrode, Whatman glass fiber as the separator, and 2 mol / L ZnCl2 as the electrolyte to assemble a zinc-iodine full cell.

[0073] Application Example 3

[0074] This application example provides a zinc-iodine full cell, which is prepared by the following steps:

[0075] 1. Add 0.273 g of zinc chloride to 1 mL of deionized water and stir at room temperature for 2 h to prepare a 2 mol / L zinc chloride solution.

[0076] 2. In Example 7, an I2@AC@PEDOT:PSS electrode was used as the positive electrode, a metal electrode as the negative electrode, Whatman glass fiber as the separator, and 2 mol / L ZnCl2 as the electrolyte to assemble a zinc-iodine full cell.

[0077] Comparative Application Example 1

[0078] This comparative application example provides a zinc-iodine full battery, which is prepared by the following steps:

[0079] 1. Add 0.273 g of zinc chloride to 1 mL of deionized water and stir at room temperature for 2 h to prepare a 2 mol / L zinc chloride solution.

[0080] 2. Using the I2@AC electrode as described in Comparative Example 1 as the positive electrode, the zinc metal electrode as the negative electrode, Whatman glass fiber as the separator, and 2 mol / L ZnCl2 as the electrolyte, assemble a zinc-iodine full cell.

[0081] To verify the performance of the zinc-iodine full battery provided in this application, the following are comparative application examples and experimental data on the performance of the zinc-iodine full battery provided in the application examples:

[0082] Figure 2 To compare the rate performance of the zinc-iodine batteries in Application Example 1 and Application Example 1. (From...) Figure 2 It can be seen that, compared with Comparative Application Example 1, the Zn / / I2 full cell in Application Example 1 exhibits superior rate performance.

[0083] Figure 3 To compare the charge-discharge curves of the zinc-iodine full cell in Application Example 1 and Application Example 1. From Figure 3 It can be seen that at 10 mgcm -2 Even with a high iodine loading, the Zn / / I2 full cell in Example 1 can still maintain a relatively sufficient I2 content. - / I2 / I + A four-electron reversible positive oxidation reaction.

[0084] Figure 4 To compare the zinc-iodine batteries in Application Example 1 and Application Examples 1-3 at 2 A g -1 Cyclic performance at current density. Figure 4 It can be seen that the high-load zinc-iodine battery in Application Example 1 can provide 288mAh g. -1 It has the capacity and retains more than 91% of its capacity after 3500 stable cycles.

[0085] Figure 5 To compare the zinc-iodine battery of Application Example 1 with that of Application Example 1 at 0.5 A g -1 Cyclic performance at current density. Figure 5 It can be seen that the full battery in Application Example 1 can provide higher capacity and can cycle stably.

[0086] Based on the disclosure and teachings of the above specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the present invention. As described in the above embodiments of the present invention, other materials and preparation methods and applications obtained using the same or similar methods and components are all within the protection scope of the present invention.

Claims

1. An iodine-containing positive electrode interface conductive polymer slurry, characterized in that, A conductive polymer slurry is formed by combining an aqueous adhesive and a PEDOT:PSS dispersion.

2. The iodine cathode interface conductive polymer slurry according to claim 1, characterized in that, The ratio of the aqueous adhesive to PEDOT:PSS is 0.00375g:0.8-1.2mL.

3. The iodine cathode interface conductive polymer slurry according to claim 1, characterized in that, The PEDOT:PSS dispersion is composed of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid in a mass ratio of 1:

6.

4. The iodine cathode interface conductive polymer slurry according to claim 1, wherein the aqueous adhesive is sodium carboxymethyl cellulose.

5. An iodine cathode based on a PEDOT:PSS conductive polymer film, characterized in that, It includes an iodine / carbon electrode sheet, wherein the surface of the iodine / carbon electrode sheet is coated with the iodine positive electrode interface conductive polymer slurry according to any one of claims 1 to 4.

6. The method for preparing the iodine cathode based on the PEDOT:PSS conductive polymer film according to claim 5, characterized in that, The steps are as follows: S1: Add the aqueous adhesive to the PEDOT:PSS dispersion and stir at room temperature to obtain a conductive polymer slurry; S2: The conductive polymer slurry prepared in step S1 is uniformly drop-coated onto the surface of the iodine / carbon electrode. After drying, a dense thin film is formed on the surface of the iodine / carbon electrode, thus obtaining an iodine cathode based on the PEDOT:PSS conductive polymer film.

7. The method for preparing an iodine cathode based on a PEDOT:PSS conductive polymer film according to claim 6, characterized in that, The stirring time in step S1 is 2-5 hours.

8. The method for preparing an iodine cathode based on a PEDOT:PSS conductive polymer film according to claim 6, characterized in that, The drying process described in step S2 involves drying in a 60°C forced-air drying oven for 30 minutes.

9. A kind of I - / I2 / I + A zinc-iodine battery with four-electron positive valence conversion is characterized by... It includes a negative electrode, an electrolyte, a separator, and a positive electrode, wherein the positive electrode is the iodine positive electrode based on the PEDOT:PSS conductive polymer film as described in claim 5.

10. The I according to claim 9 - / I2 / I + A zinc-iodine battery with four-electron positive valence conversion is characterized by... The negative electrode is a zinc metal sheet, the diaphragm is Whatman glass fiber, and the electrolyte is a halogen-containing aqueous electrolyte.

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