Preparation method of confinement type positive electrode composite material for zinc-iodine battery

Abstract

The invention discloses a preparation method of a confinement type positive electrode composite material for a zinc-iodine battery, and belongs to the technical field of zinc-iodine batteries. In order to solve the problems that an existing iodine positive electrode material is unstable in structure, prone to volume expansion, prone to active substance falling and the like, a polysaccharide material capable of adsorbing iodine substances is introduced into reduced graphene oxide, the reduced graphene oxide provides a conductive network in the positive electrode composite material, the polysaccharide substances play a role in limiting the range of polyiodide, and therefore the purpose of adsorbing the iodine substances in the positive electrode composite material is achieved. Therefore, multi-iodide shuttling is inhibited, synchronous implementation of iodine substance adsorption and material conductivity is promoted, the electrochemical performance of the zinc-iodine battery is remarkably improved, and good application prospects are achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of zinc-iodine batteries, and particularly relates to a preparation method of a confined positive electrode composite material for inhibiting the shuttling of polyiodide in a zinc-iodine battery. BACKGROUND

[0002] With the increasing demand for renewable energy and large-scale energy storage systems worldwide, developing safe, efficient, and low-cost new electrochemical energy storage technologies has become a current research hotspot. Among numerous energy storage systems, zinc-iodine batteries exhibit great application potential due to their extremely high theoretical specific capacity (~211 mAh g -1 ) of the positive electrode and abundant natural reserves. However, there are still many challenges in the commercial application of zinc-iodine batteries, and the core problem lies in the positive electrode. First, a large amount of soluble polyiodide is generated in the positive electrode during the charge and discharge process of the zinc-iodine battery, and the shuttling of polyiodide leads to continuous loss of active materials, reduction of coulombic efficiency, and capacity decay. Second, using iodine alone as the positive electrode material of the zinc-iodine battery will have problems such as low electronic conductivity and poor battery dynamics. In addition, during the battery cycle, the iodine positive electrode material itself is unstable in structure and is prone to volume expansion and active material shedding. To overcome the above problems, researchers usually adopt a "confined strategy" to confine iodine or its polyiodide in a porous host material to inhibit its dissolution and shuttling. Although traditional host materials such as various carbon materials, organic framework materials (metal-organic frameworks and covalent-organic frameworks), and conductive polymers can achieve adsorption of polyiodide, the adsorption is extremely limited, especially under long cycle conditions, and polyiodide will still gradually diffuse (J. Am. Chem. Soc., 2024, 146, 6199; Energy Storage Mater., 2025, 77, 104220; Adv. Mater., 2020, 32, 2004240; J. Energy Storage, 2024, 88, 111538). Therefore, it is of great significance to develop a low-cost zinc-iodine battery positive electrode material preparation technology that can easily prepare, effectively anchor polyiodide, and inhibit its shuttling effect. SUMMARY

[0003] In view of the problems of unstable structure, easy volume expansion, and active material shedding of the iodine positive electrode material, the application provides a preparation method of a confined positive electrode composite material for a zinc-iodine battery.

[0004] To solve the above technical problems, the application adopts the following technical solutions:

[0005] A preparation method of a confined positive electrode composite material for a zinc-iodine battery, comprising the following steps:

[0006] Step 1, dissolving polysaccharide material in water, gelatinization or heating gelatinization, then configuring with graphene oxide into a uniform solution, adding hydrogen iodide reductant, heating stirring, centrifugal cleaning, drying, preparing polysaccharide / reduced graphene oxide composite positive electrode material adsorbed with iodine material;

[0007] Step 2, loading polysaccharide / reduced graphene oxide positive electrode composite material adsorbed with iodine material on a conductive substrate, preparing a confined positive electrode for zinc-iodine battery.

[0008] Further, the polysaccharide material is any one or more of starch, chitosan, chitin, cyclodextrin, carboxymethyl cellulose, sodium alginate, pullulan, carrageenan or fucoidan.

[0009] Further, the mass ratio of the polysaccharide material to graphene oxide is 1:5~5:1.

[0010] Further, the amount of hydrogen iodide is 2~10 mL per 10 mg of graphene oxide; the concentration of hydrogen iodide is 55~58%.

[0011] Further, the temperature of heating gelatinization is 60℃~85℃.

[0012] Further, the stirring speed of heating stirring is 50~150 rpm, the heating temperature is 50~70℃, and the stirring time is 12~36h.

[0013] Further, the conductive substrate is any one of carbon cloth, carbon paper, carbon felt, carbon fiber, titanium sheet, titanium mesh, stainless steel sheet, stainless steel mesh.

[0014] A zinc-iodine battery without polyiodide shuttle, the zinc-iodine battery is assembled by a zinc negative electrode, a confined positive electrode and an electrolyte into a zinc-iodine battery without polyiodide shuttle.

[0015] Further, the electrolyte is any one of zinc chloride, zinc sulfate, zinc acetate, zinc nitrate, zinc gluconate, zinc trifluoromethyl sulfonate and a composite electrolyte of the above zinc salt and potassium iodide or zinc iodide.

[0016] Further, the concentration and volume of the electrolyte solution in the zinc-iodine battery are 100 μL of 1-2 mol L⁻¹.

[0017] Compared with the prior art, the present application has the following advantages:

[0018] 1、In the present application, hydrogen iodide is used as a reducing agent to reduce graphene oxide, and the iodine material in the by-product of reduction can be adsorbed by polysaccharide material, which is simple to operate and realizes the simultaneous realization of iodine material adsorption and material conductivity.

[0019] 2、The polysaccharide used in the application is derived from nature, is environment-friendly, has low cost, and has good adsorption performance on iodine substances. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0021] Figure 1 The zinc-iodine battery assembled by the confined type positive electrode composite material for zinc-iodine battery prepared in embodiment 1 of the present application has a cyclic voltammogram at a scanning rate of 2 mV s -1 .

[0022] Figure 2 The scanning electron microscope image and element distribution diagram of the confined type positive electrode composite material for zinc-iodine battery prepared in the present application embodiment 2.

[0023] Figure 3 The self-discharge curve diagram of the zinc-iodine battery assembled by the confined type positive electrode composite material prepared in embodiment 2 of the present application.

[0024] Figure 4 The discharge curve diagram of the zinc-iodine battery assembled by the confined type positive electrode composite material prepared in embodiment 3 of the present application after standing for 24 h (current density 0.2A g -1 ).

[0025] Figure 5 The specific capacity and coulombic efficiency diagram of the zinc-iodine battery assembled by the confined type positive electrode composite material prepared in embodiment 4 of the present application under different current densities. DETAILED DESCRIPTION

[0026] In order to better understand the present application, it will be described in detail. However, the present application has multiple implementation ways and is not limited to the specific examples listed in this paper. The presentation of these examples aims to deepen the overall understanding of the disclosure of the present application.

[0027] Embodiment 1

[0028] A preparation method of a confined type positive electrode composite material for zinc-iodine battery, comprising the following steps:

[0029] 1) 50 mg starch was added to 10 mL deionized water, heated and stirred at 70°C in a magnetic stirrer to gelatinize, 10 mg graphene oxide was slowly added, after stirring evenly, 2 mL hydroiodic acid (concentration 55-58%) was added, and the reaction was continued to heat and stir for 24 h. The above reaction was washed by centrifugation and dried to prepare a starch / reduced graphene oxide positive electrode composite material adsorbed with iodine substance.

[0030] 2) The starch / reduced graphene oxide positive electrode composite material adsorbed with iodine substance, acetylene black and carboxymethyl cellulose were ground evenly in a ratio of 8:1:1 and uniformly coated on carbon cloth, and dried at 80°C to prepare a confined positive electrode for zinc-iodine battery.

[0031] 3) A zinc negative electrode, a confined positive electrode and 100 μL 2 mol L -1 zinc sulfate and 0.1 mol L -1 potassium iodide mixed electrolyte were assembled into a zinc-iodine battery without multiple iodine shuttle.

[0032] Figure 1 The zinc-iodine battery assembled with the starch / reduced graphene oxide positive electrode composite material prepared in Example 1 was subjected to cyclic voltammetry at a scanning rate of 2 mV s -1 The cyclic voltammetry curve of the device showed obvious redox peaks at 1.41 V and 1.28 V, respectively. The difference between the redox peaks was only 0.13 V, indicating that the zinc-iodine battery prepared using the positive electrode material had good reversibility.

[0033] Example 2

[0034] A method for preparing a confined positive electrode composite material for a zinc-iodine battery, comprising the following steps:

[0035] 1) 60 mg chitosan was dissolved in 10 mL 1% acetic acid solution, 15 mg graphene oxide was slowly added, after stirring evenly, 3 mL hydroiodic acid (concentration 55-58%) was added, and the reaction was continued to heat and stir at 80°C for 30 h. The above reaction was washed by centrifugation and dried to prepare a chitosan / reduced graphene oxide positive electrode composite material adsorbed with iodine substance.

[0036] 2) The chitosan / reduced graphene oxide positive electrode composite material adsorbed with iodine substance, acetylene black and carboxymethyl cellulose were ground evenly in a ratio of 8:1:1 and uniformly coated on stainless steel mesh, and dried at 80°C to prepare a confined positive electrode for zinc-iodine battery.

[0037] 3) A zinc negative electrode, a confined positive electrode and 100 μL 1.5 mol L -1Zinc chloride and 0.1 mol L -1 Zinc iodide mixed electrolyte is assembled into a zinc-iodine battery without multi-iodide shuttle.

[0038] Figure 2 The scanning electron microscope image and element distribution image of the confined positive electrode composite material for zinc-iodine battery prepared in the embodiment 2 of the present application. As can be seen from the image, the material is in the form of sheet, and different elements are uniformly distributed in the material (wherein the carbon element is derived from graphene and chitosan, the iodine element is derived from the iodine substance generated after the reduction of graphene oxide by hydroiodic acid, and the nitrogen element is derived from chitosan), and the confined positive electrode composite material realizes uniform compounding.

[0039] Figure 3 The self-discharge curve of the zinc-iodine battery assembled by the confined positive electrode composite material prepared in the embodiment 2 of the present application. The battery is charged at a current density of 0.2 A g -1 After standing for 24 hours, the battery voltage can still retain 82%, showing good self-discharge inhibition performance.

[0040] Embodiment 3

[0041] A preparation method of a confined positive electrode composite material for zinc-iodine battery, comprising the following steps:

[0042] 1) 40 mg of cyclodextrin is added to 10 mL of deionized water, and heated and stirred in a magnetic stirrer at 70°C to gelatinize, and 30 mg of graphene oxide is slowly added, and after uniform stirring, 6 mL of hydroiodic acid (concentration 55-58%) is added, and the reaction is continued for 36 h with heating and stirring. The above reaction material is centrifuged, washed and dried to prepare a cyclodextrin / reduced graphene oxide positive electrode composite material adsorbed with iodine substance.

[0043] 2) The cyclodextrin / reduced graphene oxide positive electrode composite material adsorbed with iodine substance, acetylene black and carboxymethyl cellulose are ground uniformly at a ratio of 8:1:1 and uniformly coated on carbon cloth, and dried at 80°C to prepare a confined positive electrode for zinc-iodine battery.

[0044] 3) A zinc negative electrode, a confined positive electrode and 100 μL of 1 mol L -1 Zinc gluconate electrolyte is assembled into a zinc-iodine battery without multi-iodide shuttle.

[0045] Figure 4 The discharge curve of the zinc-iodine battery assembled by the confined positive electrode composite material prepared in the embodiment 3 of the present application after standing for 24 h (current density 0.2 A g -1Compared with the discharge curve without standing, the discharge curve after standing for 24 h still has a capacity retention of 83.3%, indicating that the material effectively inhibits the capacity reduction problem caused by the polyiodide shuttle effect.

[0046] Example 4

[0047] A preparation method of a confined positive electrode composite material for a zinc-iodine battery comprises the following steps:

[0048] 1) 50 mg of carboxymethyl cellulose is added to 10 mL of deionized water, and stirred until the gel is colorless and transparent. 50 mg of graphene oxide is slowly added, and after uniform stirring, 10 mL of hydriodic acid (concentration 55-58%) is added, and the reaction is continued for 36 h with heating and stirring. The above reaction material is centrifuged, washed and dried to prepare a carboxymethyl cellulose / reduced graphene oxide positive electrode composite material adsorbed with iodine substances.

[0049] 2) The carboxymethyl cellulose / reduced graphene oxide positive electrode composite material adsorbed with iodine substances, acetylene black and carboxymethyl cellulose are ground uniformly at a ratio of 8:1:1 and uniformly coated on carbon cloth, and dried at 80°C to prepare a confined positive electrode for a zinc-iodine battery.

[0050] 3) A zinc negative electrode, a confined positive electrode and 100 μL of 2 mol L -1 -1 zinc acetate electrolyte are assembled into a zinc-iodine battery without polyiodide shuttle.

[0051] Figure 5 The specific capacity and coulombic efficiency of the zinc-iodine battery assembled with the confined positive electrode composite material prepared in Example 4 of the present application at different current densities. When the current density is 0.2 A g -1 -1, the device capacity can reach 121.6 mAh g -1 -1, and the coulombic efficiency is 92.7%; when the current density is 5 A g -1 -1, the device capacity can reach 86.7 mAh g -1 -1, and the coulombic efficiency is 99.2%. The zinc-iodine battery assembled with the confined positive electrode composite material prepared by the method has good rate performance and high coulombic efficiency.

[0052] In summary, the method is to mix polysaccharide gel and graphene oxide together, and then add hydriodic acid to reduce graphene oxide, obtaining conductive reduced graphene oxide. At the same time, the by-product (polyiodide substance) of the reaction of hydriodic acid and graphene oxide can also be adsorbed by the polysaccharide gel, and a polysaccharide gel with excellent conductivity, adsorbed with iodine substances and inhibiting polyiodide shuttle is obtained in one step.

[0053] The details of the application not described herein are considered known to those skilled in the art. Although the foregoing description of the application has been described in some detail for the purposes of clarity and the understanding of the application, it should be apparent that certain changes and modifications can be practiced within the scope of the application as defined by the appended claims.

Claims

1. A method for preparing a confined positive electrode composite for zinc-iodine batteries, characterized in that, The method comprises the following steps: Step 1, dissolving the polysaccharide material in water, gelatinizing or heating to gelatinize, then configuring into a uniform solution with graphene oxide, adding a hydroiodic acid reducing agent, heating and stirring, centrifugal cleaning, drying, and preparing a polysaccharide / reduced graphene oxide composite positive electrode material adsorbed with iodine; Step 2, loading the polysaccharide / reduced graphene oxide positive electrode composite material adsorbed with iodine on a conductive substrate to prepare a confined positive electrode for a zinc-iodine battery.

2. The method according to claim 1, wherein the method is characterized by, The polysaccharide material is any one or more of starch, chitosan, chitin, cyclodextrin, carboxymethyl cellulose, sodium alginate, pullulan, carrageenan or fucoidan.

3. The method according to claim 1, wherein the method is characterized by, The mass ratio of the polysaccharide material to graphene oxide is 1:5 to 5:

1.

4. The method according to claim 1, wherein the method is characterized by, The amount of hydroiodic acid is 2 to 10 mL per 10 mg of graphene oxide; the concentration of the hydroiodic acid is 55 to 58%.

5. The method of claim 1, wherein the method is characterized by: The temperature of the heating gelatinization is 60 to 85°C.

6. The method according to claim 1, wherein the method is characterized by, The stirring speed of the heating and stirring is 50 to 150 rpm, the heating temperature is 50 to 70°C, and the stirring time is 12 to 36 h.

7. The method according to claim 1, wherein the method is characterized by, The conductive substrate is any one of carbon cloth, carbon paper, carbon felt, carbon fiber, titanium sheet, titanium mesh, stainless steel sheet or stainless steel mesh.

8. A zinc-iodine battery without polyiodide shuttling, characterized by: The zinc-iodine battery is assembled by a zinc negative electrode, a confined positive electrode and an electrolyte into a zinc-iodine battery without polyiodide shuttling; the confined positive electrode is the confined positive electrode for a zinc-iodine battery prepared by the preparation method of any one of claims 1 to 7.

9. A zinc-iodine battery without polyiodide shuttling according to claim 8, characterized in that The electrolyte is any one of zinc chloride, zinc sulfate, zinc acetate, zinc nitrate, zinc gluconate, zinc trifluoromethyl sulfonate and a composite electrolyte of the above zinc salt and potassium iodide or zinc iodide. The electrolyte is any one of zinc chloride, zinc sulfate, zinc acetate, zinc nitrate, zinc gluconate, zinc trifluoromethyl sulfonate and a composite electrolyte of the above zinc salt and potassium iodide or zinc iodide.

10. A zinc-iodine battery without polyiodide shuttling according to claim 8, characterized in that The concentration and volume of the electrolyte solution in the zinc-iodine battery is 1-2 mol L -1 , 100 μL.

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